EPA/625/R-96/004
September 1996
Manual
Best Management Practices for Pollution Prevention in the
Textile Industry
U.S. Environmental Protection Agency
Office of Research and Development
National Risk Management Research Laboratory
Center for Environmental Research Information
Cincinnati, Ohio
Printed on Recycled Paper
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Notice
This document has been subjected to the U.S. Environmental Protection Agency's (EPA's) peer and
administrative review and has been approved for publication as an EPA document. The contents of
this document do not necessarily reflect the views and policies of .the EPA, nor does mention of
trade names or commercial products constitute endorsement or recommendation for use. This
document is intended as advisory guidance only to textile facilities in developing approaches for
pollution prevention. Compliance with environmental and occupational safety and health laws is the
responsibility of each individual business and is not the focus of this document.
Users are encouraged to duplicate portions of this publication as needed to implement a waste
minimization plan.
When an NT1S number is cited in a reference, that document is available from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
703-487-4650
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FOREWORD
The U.S. Environmental Protection Agency is charged by Congress with protecting the Nation's
land, air, and water resources. Under a mandate of national environmental laws, the Agency strives to
formulate and implement actions leading to a compatible balance between human activities and the ability
of natural systems to support and nurture life. To meet this mandate, EPA's research program is providing
data and technical support for solving environmental problems today and building a science knowledge
base necessary to manage our ecological resources wisely, understand how pollutants affect our health,
and prevent or reduce environmental risks in the future.
The National Risk Management Research Laboratory is the Agency's center for investigation of
technological and management approaches for reducing risks from threats to human health and the
environment. The focus of the Laboratory's research program is on methods for the prevention and control
of pollution to air, land, water and subsurface resources; protection of water quality in public water systems;
remediation of contaminated sites and ground water; and prevention and control of indoor air pollution. The
goal of this research effort is to catalyze development and implementation of innovative, cost-effective
environmental technologies; develop scientific and engineering information needed by EPA to support
regulatory and policy implementation of environmental regulations and strategies.
This publication has been produced as part of the Laboratory's strategic long-term research plan.
It is published and ma^ available by EPA's Office of Research and Development to assist the user
community and to lin|tesearchen> with their clients.
This manual,, Besf Management Practices for Pollution Prevention in the Textile Industry, funded
through the Center for Environmental Research Information, is a pollution prevention guidance manual for
processes and waste reduction in the textile industry.
E. Timothy Oppelt, Director
National Risk Management Research Laboratory
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ABSTRACT
Textiles is one the nation's oldest industries, dating back to be beginning of the American
industrial revolution in the 1790s. Despite perceptions of the decline of U.S. textile manufacturing in the
face of offshore competition, the industry remains one of the largest, most diverse, and dynamic segments
of the U.S. manufacturing sector.
This manual represents a comprehensive history of the U.S. textiles industry, describes
wastestreams from diverse industrial processes and products, and provides excellent pollution prevention
solutions to guide the environmental responsibility of the industry. The audience for this manual can range
from small and medium-size companies in textile-related manufacturing to those involved in regulation,
permitting and assistance in environmental management and pollution prevention planning.
This document is divided into eight sections, briefly described below. It has a comprehensive index
to assist in selected topic searching.
1 An overview of the textiles industry in the United States, describing production processes
and the technological base of the industry, with major waste and pollution issues that exist.
2. A general categorization for wastes generated in the textiles industry.
3. General P2 approaches applicable throughout the textiles industry.
4! Pollution prevention opportunities are identified for specific textile processes or operations,
covering raw material handling and usage, yarn formation, slashing and sizing, fabric
formation, textile preparation, dyeing, printing, finishing, and cutting and sewing operations.
5. A composite list of the key P2 features offer a comprehensive and effective plan for
development and implementation of a successful program.
6. Business considerations of pollution prevention are discussed with incentives and barriers
to implementation of a program.
7. A selection of published case studies exemplifying successful implementation of pollution
prevention in textile processing
8. A comprehensive listing of references.
This report was submitted in fulfillment of Contract #68-3-0315 by Eastern Research Group, Inc.
under the sponsorship of the U.S. Environmental Protection Agency. This report covers a period from April,
1994, to September, 1996, and work was completed as of September 30,1996.
IV
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Contents
Page
Foreword iii
Abstract iv
Figures. xii
Tables xjv
Conversion Factors xviii
Acknowledgments , ' xix
Chapter 1 Introduction 1
1.1 Industry Overview 1
1.1.1 Textile Facilities 2
1.1.2 Machinery 3
1.1.3 Fiber 11
1.1.4 Products 11
1.2 Overview of Pollutants and Waste Streams 11
1.2.1 Air Pollutants 11
1.2.2 Water Pollution 16
1.2.3 Solid Wastes 20
1.2.4 Hazardous Waste 24
1.3 Summary 27
1.4 References 28
Chapter 2 Waste Categorization/Prioritization for the Textile Industry ... 31
2.1 General Waste Categorization 31
2.1.1 Dispersible Wastes 31
2.1.2 Hard-To-Treat Wastes 32
2.1.3 High-Volume Wastes 33
2.1.4 Hazardous or Toxic Wastes 33
2.2 Specific Wastes or Waste Problems : 33
2.2.1 Color Residues in Dyeing Wastewater 34
2.2.2 Discharge of Electrolytes 38
2.2.3 Toxic Air Emissions 44
2.2.4 Improving Treatability 50
2.2.5 Metals. 52
2.2.6 Aquatic Toxicity 57
2.2.7 Water Conservation 64
2.3 References 74
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Contents (continued)
Page
Chapter 3 General Pollution Prevention Approaches Applicable Throughout the Textile Industry .. 77
3.1 Building Blocks of an Effective Pollution Prevention Program 77
3.1.1 Management Commitment ~ 77
3.1.2 Employee Commitment • 77
3.1.3 Low-Technology Approaches 77
3.1.4 High-Technology Approaches 78
3.1.5 Long-Term Commitment 78
3.1.6 Documenting Accomplishments • 78
3.1.7 Right-First-Time Production 79
3.2 Design-Stage Planning for Facilities, Processes, and Products 79
3.2.1 Design-Stage Planning for Processes 79
3.2.2 Design-Stage Planning for Products 81
3.2.3 Design-Stage Planning for Facilities 83
3.3 Enhanced Chemical and Pollution Prevention Expertise. 34
3.3.1 Training 84
3.3.2 Education • • • 85
3.4 Equipment Maintenance and Operations Audit 86
3.4.1 Major Machinery 86
3.4.2 Leaks • 87
3.4.3 Filters 87
3.4.4 Automatic Chemical Systems 88
3.4.5 Calibrations of Chemical Measuring and Dispensing Devices 88
3.4.6 Employee Input 88
3.5 Chemical Alternatives 88
3.5.1 Chemical Substitutions 89
3.5.2 Obtaining Information on Substitutions 89
3.5.3 Typical Substitutions • • 91
3.5.4 Tradeoffs 92
3.5.5 Phosphates ..., • 92
3.5.6 Biological Oxygen Demand and Chemical Oxygen Demand 93
3.5.7 Solvents • • • 93
3.6 High-Extraction, Low-Carryover Process Step Separations 94
3.6.1 Wet Pickup Minimization 95
3.6.2 Wet-on-Wet Processing • 95
3.6.3 Process Step Separations • 95
3.6.4 Recovery of Offensive Materials 96
3.6.5 High-Extraction/Low-Add-On, Devices 96
3.7 Incoming Raw Material Quality Control 96
3.8 Maintenance, Cleaning, and Nonprocess Chemical Control 97
3.8.1 Solvents 97
vi
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Contents (continued)
Page
3.9 Developing Markets for Wastes .....;.,....... ...; 97
3.10 Process Alternatives 98
3.10.1 Improved Coatings Systems .. 98
3.10.2 "Cold" Processes 99
3.11 Optimized Chemical Handling Practices 100
3.11.1 Purchasing 100
3.11.2 Packaging 100
3.11.3 Receiving ...'.. 100
3.11.4 Storage . 100
3.11.5 Mixing... 101
3.11.6 Worker Training, Expertise, and Attitudes ; 101
3.11.7 Automated! Chemical Systems 101
3.12 Raw Material Prescreening (Before Use) 102
3.12.1 Types of Chemicals ..: 102
3.12.2 Evaluation Committee 103
3.12.3 Evaluation Policy 104
3.13 Disinformation About Environmental Issues '...:.. 104
3.14 Scheduling Dyeing Operations To Minimize Machine Cleaning 104
3.15 Standard Tests, Methods, and Definitions 105
3.16 Consumer, Installer, and End-User Information , 105
3.17 Segregation and Direct Reuse • • • • 106
3.18 Improved Process Control , 106
3.18.1 Automated! Mix Kitchens 106
3.18.2 Chemical Dosing Systems 106
3.18.3 Control, Automation, Scheduling, and Management Systems 106
3.18.4 Real-Time Sensors and Advanced Control Strategies 107
3.19 Pollution Prevention Through New Equipment 107
3.19.1 Proven Commercial Technologies 107
3.19.2 Emerging Technologies 116
3.20 References 118
Chapter 4 Pollution Prevention in Specific Textile Processes 121
4.1 Introduction : 121
4.2 Fibers 121
4.2.1 Natural Fibers 122
4.2.2 Synthetic and Regenerated Fibers 125
4.2.3 Pollution Prevention Strategies 126
4.3 Dyes 127
4.3.1 General Background 128
VII
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Contents (continued)
Page
4.3.2 Dyes and Dye Processes 129
4.3.3 Characteristics of Dyes 132
4.3.4 End-Use Classes 134
4.3.5 Environmental Classification 135
4.3.6 Pollution Prevention Measures 136
4.4 Chemical Specialties 137
4.4.1 Proprietary Nature of Chemical Specialties 138
4.4.2 Types of Chemical Specialties 140
4.4.3 Pollution Prevention 146
4.4.4 Other Pollution Prevention Measures 147
4.5 Chemical Commodities • 15°
4.5.1 Commodities Versus Specialties 150
4.5.2 Types of Commodities 150
4.5.3 Quality Control for Incoming Commodities 151
4.5.4 Bulk Systems/Automated Dispensing 151
4.6 Yarn Formation 152
4.6.1 Yarn Formation Processes 153
4.6.2 Types of Waste Associated With Spinning 156
4.6.3 Pollution Prevention in Short Staple Spinning 157
4.6.4 Other Waste Issues 159
4.7 Slashing and Sizing 159
4.7.1 Unit Process Description 161
4.7.2 Warp Size Types and Properties 161
4.7.3 Desizing 163
4.7.4 Identification of Wastes and Pollutants 163
4.7.5 Pollution Prevention Measures 165
4.8 Fabric Formation 168
4.8.1 Fabric Formation Unit Processes 168
4.8.2 Pollution Prevention in Weaving 168
4.8.3 Pollution Prevention in Knitting Operations 169
4.8.4 Fabric Quality Factors 169
4.8.5 Lubricant Use 169
4.8.6 Fabric Design Factors 169
4.8.7 Pollution Prevention in Carpetmaking 169
4.9 Preparation 170
4.9.1 Preparation Processes 171
4.9.2 Summary of Pollution Prevention Strategies for Preparation Pollutants 173
4.9.3 Pollution Prevention Through Equipment Selection and Use 175
VIII
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Contents (continued)
Page
4.10 Dyeing • • 176
4.10.1 Introduction to Dyeing Processes 178
4.10.2 Pollutants Associated With Dyeing 179
4.10.3 Pollution Prevention in Specific Dyeing Situations 180
4.10.4 Batch Dyeing Pollution Prevention Measures 183
4.10.5 Continuous Dyeing Pollution Prevention Measures 185
4.10.6 General Pollution Prevention Measures . 186
4.10.7 Emerging Pollution Prevention Technologies 191
4.11 Printing • 191
4.11.1 Printing Techniques • 192
4.11.2 Pollutants Associated With Textile Printing 193
4.11.3 Specific Pollution Prevention Strategies 194
4.11.4 Pollution Prevention Practices 195
4.12 Finishing • • • • 199
4.12.1 Types of Pollutants 200
4.12.2 Pollution Prevention for Major Waste Categories 200
4.12.3 Pollution Prevention for Fabrics Other Than Wool 201
4.12.4 Pollution Prevention Practices for Wool Finishing 206
4.13 Cutting, Sewing, and Product Fabrication 208
4.13.1 Amounts of Waste Generated 209
4.13.2 Pollution Prevention To Reduce Waste Levels 209
4.14 Installation 210
4.15 Aftermarket Treatments 210
4.16 Consumer Issues and Consumer Care 211
4.17 Globalization of Pollution Prevention 211
4.17.1 Scope of Globalization 212
4.17.2 Barriers to Globalization 212
4.17.3 Examples of Globalization 212
4.17.4 Priorities and Commitments. 214
4.18 Support Work Areas 214
4.18.1 Design Features 214
4.18.2 Employee Work Practices 214
4.18.3 Implements • •• • • 215
4.18.4 Mix Tanks 215
4.18.5 Cleanup Practices 215
4.18.6 Automated Chemical Dispensing Systems 215
4.19 References 216
Chapter 5 Implementation of a Pollution Prevention Program 219
5.1 Steps in Implementation • 219
ix
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Contents (continued)
Page
5.1.1 Establishing Management Commitment and Support 219
5.1.2 Designating a Pollution Prevention Coordinator 220
5.1.3 Organizing a Pollution Prevention Team 220
5.1.4 Developing a Pollution Prevention Plan 221
5.1.5 Developing a Process Flow Diagram 221
5.1.6 Setting Goals and Priorities 222
5.1.7 Developing an Action Plan 222
5.1.8 Implementing the Action Plan 230
5.1.9 Expanding the Action Plan 230
5.1.10 Renewal 231
5.2 Waste Audit 231
5.2.1 Steps for Performing a Waste Audit 231
5.2.2 Sampling 232
5.2.3 Plant Survey Methods and Procedures 233
5.2.4 Evaluation and Selection of Waste Reduction Techniques 233
5.2.5 Waste Minimization Program Implementation and Monitoring 235
5.2.6 Air Inventory 235
5.2.7 Forms and Lists 236
5.3 Training Programs and Worker Attitudes 236
5.3.1 Importance of Training Programs 236
5.3.2 Information To Include in Worker Training 237
5.4 Technology Transfer 237
5.5 References 238
Chapter 6 Pollution Prevention Incentives and Overcoming Barriers to Pollution Prevention 239
6.1 The Need for Integration : 239
6.1.1 ISO 14000 Environmental Standards 239
6.1.2 Other Initiatives 240
6.2 Business Opportunities and Pollution Prevention Needs 241
6.2.1 Marketing of Waste By-Products 241
6.2.2 Consumer Information 241
6.3 Priorities and Commitments 241
6.4 Conflicting Goals 242
6.4.1 Water Conservation 242
6.4.2 Low BOD Versus Pass-Through Aquatic Toxicity 243
6.4.3 Dye Stability Versus Treatability 243
6.4.4 Quality Considerations and High-Value Products 243
6.4.5 Proprietary Issues 243
6.4.6 Segregation and Capture Versus Disposal Facilities 243
6.4.7 Cost 244
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Contents (continued)
Page
6.4.8 Marketing • • 244
6.5 Risk Assessment Methods, Data, and Procedures 244
6.5.1 Tradeoffs in Benefits and Risk 244
6.5.2 Barriers: Known Versus Unknown 245
6.5.3 Overcoming Barriers • • 245
6.6 Human Resources 246
6.6.1 Workers and Supervisors 246
6.6.2 Management and Staff 246
6.7 Technical Understanding of Processes 247
6.8 References • • • 247
Chapter 7 Selected Case Studies of Pollution Prevention in the Textile Industry 249
Appendix A ATMI's E3 Program: Encouraging Environmental Excellence Report 1995 273
Index • • • • • 291
XI
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Figures
Figure
Page
1-1 Dyeing machinery 8
2-1 Relationship between affinity, reactivity, and fixation efficiency 38
2-2 Adsorption isotherms of Chrysophenine G on cellulose sheet at 40°C and varying salt concentrations .. 40
2-3 Salt requirements for various dye classes—batch dyeing of cotton 41
2-4 Vertical and horizontal washer configurations 68
2-5 Pad with displacer 4 69
2-6 Flow diagram for chlorination water treatment system 70
2-7 Ozone generation equipment 71
2-8 Recycle of jet dyeing machine flows using ultrafiltration '. 71
2-9 Ozone decolorization of Disperse Yellow 42 72
2-10 Dye decolorization by ozone 72
2-11 Ozone oxidation of auxiliaries 72
2-12 Typical membrane configuration for ultrafiltration. 73
2-13 Tangential flofiltration 73
3-1 Waste reduction achievements as a function of pollution prevention efforts over time 77
3-2 Waste reduction and new technology development 80
3-3 Computerization of the preprint process 82
3-4 Schematic of a small parts cleaning system 94
3-5 Wet-on-wet processing to eliminate drying stage 95
3-6 Incoming raw materials that should undergo QC testing 96
3-7 Schematic of (A) powder coating scatter, (B) paste point coating, and (C) powder paint coating
using gravure roller 99
3-8 Vibrascrew dispense system 102
3-9 Dyeing machine configured for dyebath reuse 108
3-10 Schematic of PVA size recovery 109
3-11 Continuous dyeing of tubular cotton knits 110
3-12 Automated process control system 111
3-13 ULLR piece dyeing 112
3-14 Mechanical shrinking of goods using rubber-belt method 113
3-15 Quick-change S-roil pad to reduce startup, stopoff, and changeover losses 114
3-16 Transfer printing of disperse dyes on polyester 115
3-17 Foam finishing for low add-on 115
3-18 High-extraction removal before dyeing 116
3-19 Cause-effect diagram for shade variation in batch dyeing 117
4-1 Relationship between dye exhaust and affinity 130
4-2 Predicted hazardous nature of dyes 135
4-3 Some mutagenic dye intermediates and nonmutagenic alternatives 136
4-4 Production sequence for synthetic continuous filament yarn production 154
4-5 Stages in the manufacture of yarns for long staple spinning 155
XII
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Figures (continued)
Figure
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4-8
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5-2
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6-1
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Stages in the manufacture of yarns for short staple spinning 156
Average percent Shirley Analyzer nonlint content of white cotton grades .158
PVA size recovery system 166
Potential waste savings from reducing runout from dye samples 170
Potential waste savings in converting to butt seams from lap seams in carpet 170
Reuse of alkaline waste streams from desizing and scouring operations 174
Horizontal washer configuration 175
Comparison of three alternative desizing methods on different types of size 177
Schematic of jet dyeing machine 179
Low-temperature chrome dyeing, time/temperature profile 182
Cost curves comparing pad-batch dyeing and jet dyeing 188
Cost curves comparing pad-batch dyeing and continuous dyeing • 188
Source reduction of chemicals in textile printing • 193
Schematic of rayon preparation/printing • • • 198
Modifications to a centrifuge (hydroextractor) for application of mothproofing agent solution 207
Implementation of "best" mothproofing strategy by carpet industry in Kidderminster, United Kingdom .. 208
AOX loads and concentrations from each of the six bowls of a continuous chlorine/Hercosett plant 209
An integrated approach to environmental problems in the textile industry 213
Vibrascrew dispense system 216
Dispense and weigh scale set-up 216
A management policy statement. 22°
Materials flow for cotton knit golf shirt 223
Materials flow for polyester woven dress 227
Waste reduction heirarchy 235
An entity relationship diagram from the retail perspective : 240
XIII
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Tables
Table
1-1 Number of Establishments in the Textile Industry by Three-Digit SIC Code
1-2 Comparison of Dyeing Equipment
1-3 Textile Industry Categorization
1-4 Value of Shipments Data, 1987
1-5 Typical Operating Temperatures of Textile Operations Contributing to Air Emissions
1-6 Air Emissions From Drapery Materials
1-7 Air Emissions From Drapery Linings
1-8 Listed Chemicals From MSDSs for Textile Finishing Agents
1-9 Water Consumption and Wastewater Discharge Volumes by Subcategory
1-10 Median Raw Waste Concentrations by Subcategory
1-11 Median Raw Waste Loads by Subcategory
1-12 Permitted Discharges (Survey of Six Cities, 1991 to 1994)
1-13 Examples of Economic Surcharges Applied to Effluent Characteristics (1991 to 1994 Survey).
1-14 Priority Areas for Pollution Prevention in Textile Operations
1-15 Common Solid Waste Materials in Textile Processing
1-16 Packaging Wastes Used in Five Textile Plants
1-17 Cost Factors in Textile Wastes
1-18 Drum Sizes for Textile Chemicals
2-1 Degradability of Alternative Pesticides in Wastewater Treatment Systems
2-2 Typical Exhaustion/Fixation Rates for Dyes of Various Classes
2-3 Wastewater Color Values Derived From Different Combinations of Dyes, Substrates, and
Dyeing Equipment
2-4 Comparison of Steps in Alternative Dyeing Procedures for Fiber Reactive Dyes
2-5 Types of Salt Used in Textile Operations and Toxicity Characteristics
2-6 Typical Amounts of Salt Used or Generated in Textile Operations
2-7 Types of Salt Discharged From Various Process Sources
2-8 Salt Requirements of Various Dyeing Machines
2-9 Salt Required to Produce 50-Percent Exhaustion of Direct Dyes
2-10 Typical Salt Application for Direct and Reactive Dyes on Cotton
2-11 Maximum Affinity Temperature of Commercial Dyes
2-12 Initial List of 189 Hazardous Air Pollutants Identified in the Clean Air Act Amendments of 1990
2-13 Hazardous Air Pollutants Found in Textile Plants
2-14 Nonchemical Methods To Assist in Eliminating Dyeing Auxiliaries
2-15 Typical Short-Term Variations in Processing Bath Parameters
2-16 Typical Sources of Metals in Effluent
2-17 Typical Metals Found in Dyes by Dye Class
2-18 Average Metal Concentration of Selected Dyes
2-19 Dyes With High Copper Content
2-20 Replacements for Dichromate, Permanganate, and Zinc Oxidizing Agents
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XIV
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Tables (continued)
Table
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2-26
2-27
2-28
2-29
2-30
2-31
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2-35
2-36
3-1
3-2
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3-4
3-5
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4-5
4-6
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4-8
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62
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Page
Contaminants in Processing Solutions in Textile Mills: Peroxide Saturator Solutions From
Three Mills Bleaching Cotton Fabric in J Boxes -55
Trace Element Analysis of Cotton After Preparation • • 56
Raw Water Quality in Textile Mills in Southeastern United States 56
Non-Copper-Containing Direct and Fiber Reactive Dyes 57
List of EPA Priority Pollutants • 58
Results From Aquatic Toxicity Testing of Effluent From 75 Textile Mills 59
Typical Causes of Aquatic Toxicity • 60
Effect of 46 Selected Dyes on the Fathead Minnow, Pimephales Promelas, in Static Bioassay Tests 60
Frequency Distribution of Toxicity Test Results for 46 Commercial Dyes
Toxicities of Various Dye Classes
Toxic Organics Detected in Wastewater From Five Textile Wet Processing Mills .
Aquatic Toxicities of Organic Chemicals Found in Effluent From Five Textile Mills
Water Use in Textile Processing • • 65
Water Consumption by Unit Process • • • 65
Water Consumption for a Typical Bleach Range 66
Water Use in Batch Washing 67
Known Pollution Source Reduction Strategies That Are Widely Used in Textiles 78
Future Pollution Prevention Innovations for the Textile Industry 78
Pollution Prevention Techniques in the Chemical Industry 79
Suitability of Waste Management Options Checklist 79
Examples of Mechanical Processes That Substitute for Chemical Processing Assistants 81
Routine Maintenance Checklist for Dye Becks = 87
Operations Checklist for Dye Becks • • • • • • 87
Pollution Capability of Some Chemicals/Products Used in the Textile Industry 90
Chemical Classification Scheme for the Textile Industry • 90
Environmental Database Parameters 91
Published BOD and COD Data for Selected Chemical Products Used in Textile Operations 92
Available Substitutions for Phosphates • • • • • 92
Typical WPU Values for Saturation Expression Processes on Previously Dry Fabric 94
Examples of Textile Industry Waste Materials That Can Be Exchanged 98
Process Alternatives That Can Reduce Pollution 99
Estimated Savings.With ULLR Dyeing Equipment. • 112
Results of Tests on Knit Finishing System Using Vacuum Technology 115
Natural Fiber Sources • • • • 122
Natural Fiber Contaminants and Associated Pollution Problems 122
Results of Pesticide Residue Sampling in Cotton From Growing Regions Worldwide 123
Presence of BOD, COD, and Metals in Cottons • 124
Metals Present in Prepared Cotton 124
Metals Content of Raw Water and Textile Processing Solution 124
PCP Levels in Wool Carpet 125
PGP Levels in Carpet Components Other Than Wool 125
xv
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Tables (continued)
Table
4-9 Organochloride Pesticide Levels Detected in Samples From Different Wool-Producing Regions
4-10 Synthetic and Regenerated Fibers
4-11 Impurities Associated With Synthetic Fibers
4-12 Contaminant Levels in Synthetic Fiber Extracts
4-13 Compounds Typical of Synthetic Fiber Extracts
4-14 Metals Concentrations in Extracts From Synthetic Fibers (ppm)
4-15 Exhaustion/Fixation Levels for Various Dye Classes
4-16 Wastewater Color Values From Various Dye/Substrate/Dye Method Combinations
4-17 Dye Classes and Fibers for Which They Have Affinity
4-18 Predicted Hazardous Nature of Dyes; All Dyes Except Vats, Sulfurs, Foods, and Brighteners...
4-19 Categories of Proprietary Chemical Specialties in the Textile Industry
4-20 Chemical Sales to the Textile Industry
4-21 Consumption of Surfactants in Textiles
4-22 BODs of Detergents and Surfactants: Product 5-Day BOD (ppm)
4-23 BOD of Dyebath Auxiliary Chemicals: Product Five-Day BOD (ppm)
4-24 Aquatic Toxicity of Surfactants
4-25 Examples of Commodity Chemicals Used in Textiles
4-26 Fibers Typically Used in Filament Form
4-27 Sizing Materials Used for Filament Yarns
4-28 Categorization of Spun Yarn Sizing Materials
4-29 Environmental Advantages and Disadvantages of Alternative Synthetic Sizes
4-30 BODs of Various Warp Sizes
4-31 BODs of Various Size Materials
4-32 BOD and Aquatic Toxicity of Warp Size Additives
4-33 Amounts and Value of Waste in Carpet Manufacturing
4-34 BOD From Preparation Processes
4-35 Alternative Recipes for Desizing Processing Baths
4-36 Types of Pollutants Associated With Various Dyes <
4-37 BOD of Dyeing Auxiliaries (ppm)
4-38 Dyebath Chromium Residues With Optimized Chroming
4-39 Normal (Conventional) Bath Ratios
4-40 Examples of Dyes Used in Pad-Batch Dyeing
4-41 Cost Comparison of Pad-Batch Dyeing Machines With Conventional Exhaust Dyeing Machines
4-42 Comparison of Typical Dye Costs for Pad-Batch Versus Beck Dyeing
4-43 Dyebath Analysis Equipment and Procedures
4-44 Dyebath Reuse Applications
4-45 Typical Costs and Savings for Dyebath Reuse per Dye Machine
4-46(a) Survey of Printing Techniques: By Application Method
4-46(b) Survey of Printing Techniques: By Dye Class
4-47 Pollutants Associated With Textile Printing and Their Sources
4-48 Water and BOD Generated by Process
4-49 Print Paste Recipes
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XVI
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Tables (continued)
Table Page
4-50 Ink-Jet Dye Types 195
4-51 Comparison of Relative Color Values From Prints on Cotton With Matexil FN-T-Treated/Reduced
Urea Recipe and Near-Optimum Urea Alone 198
4-52 Comparison of High-Urea Print Recipe Versus Reduced-Urea Recipe on Causticized Viscose. 199
4-53 Pollutants Detected in Textile Mill Air Emissions 201
4-54 Examples of Mechanical Finishes and Design Alternatives That Avoid Chemical Processing 202
4-55 Types of Softeners Used in Textiles and Their Environmental Considerations 202
4-56 Commercial Low Add-On Finishing Processes 205
4-57 Optimum Wet Pickup Levels for Various Cotton Fabrics 205
4-58 European Community Directives on Aquatic Pollution From Mothproofing Agents Used for Wool 207
4-59 Use of Spray/Centrifuge Techniques To Reduce Discharges of Permethrin 208
4-60 Typical Levels of Cutting Room Wastes .210
5-1 Sources of Facility Information 221
5-2 Potential Sources of Waste 233
5-3 Examples of Information Obtained From In-Plant Survey 233
5-4 Information Collected During an Audit 234
5-5 Sources of Case Study Information on Pollution Prevention in Textiles 237
6-1 Waste Hazards and Exposure Potentials 244
6-2 Control Points for Pollution Prevention Techniques 245
6-3 Computer Simulation of Cost Impacts of Pollution Prevention in Dyeing 246
XVII
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Conversion Factors
To convert...
to...
multiply by...
cubic feet
degrees Fahrenheit
feet
Inches
pounds
pounds per cubic foot
pounds per cubic foot
square inches
tons
U.S. gallons
cubic meters
degrees Celsius
meters
centimeters
kilograms
kilograms per cubic meter
kiloPascals
square inches
metric tons
liters
2.831685 x10"2
f.c=(f.F-32)/1.8
0.3048
2.54
0.45354237
16.0184634
6.895
6.4516
0.90718474
3.785
XVIII
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Acknowledgments
This guide was prepared under the direction and coordination of Douglas Williams and Emma Lou
George of the U.S. Environmental Protection Agency's (EPA's) Center for Environmental Research
Information (CERI), located in Cincinnati, Ohio. Eastern Research Group, Inc. (ERG), of Lexington,
Massachusetts, in consultation with Dr. Brent Smith of the College of Textiles, North Carolina State
University, prepared the information used in this guide under contract to CERI. Jeff Cantin was
ERG's project manager.
The following individuals contributed material to this guide and/or reviewed portions of it for technical
accuracy and completeness. Their assistance is kindly appreciated.
Jane Henriques
American Textile Manufacturers Institute
Washington, DC
Bob Carter
Waste Reduction Resource Center of the
Southeast
Raleigh, NC
Charles Livengood
North Carolina State University
Raleigh, NC
Bob Pojasek
Cambridge Environmental, Inc.
Cambridge, MA
Cliff Seastrunk
North Carolina State University
Raleigh, NC
David Williams
North Carolina Office of Waste Reduction
Raleigh, NC
Dennis Stein
3M Corporation
St. Paul, MN
Don Bailey
North Carolina State University
Raleigh, NC
Hechmi Hamouda
North Carolina State University
Raleigh, NC
Jeff Silliman
Milliken and Company
Spartenburg, SC
Jim Walters
West Point Stevens
Lumberton, NC
Kathy Powell
University of South Carolina
Columbia, SC
Lou Kravetz
Shell Development Corporation
Houston, TX
Margot Baird
Scottish College of Textiles
Scotland, United Kingdom
Sam Moore
Burlington Research Corporation
Burlington, NC
Ruben Carbonell
North Carolina State University
Raleigh, NC
Warren Perkins
Auburn University
Auburn, AL
Arthur Toompas
Cone Mills Corporation
Greensboro, NC
Ed Fouche
North Carolina State University
Raleigh NC 27695
XIX
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Chapter 1
Introduction
This chapter provides a brief overview of the textile
industry in the United States, focusing on the production
processes and technological base of the industry (Sec-
tion 1.1) and identifying major waste and pollution is-
sues (Section 1.2). The discussion of equipment and
processes serves as background to later sections that
describe process alternatives or equipment modifica-
tions to achieve pollution prevention, while the discus-
sion of pollution and wastes provides an understanding
of the nature, types, sources, and amounts of wastes
associated with textile operations.
1.1 Industry Overview
The textile industry is one of the nation's oldest, dating
back to the beginning of the American industrial revolu-
tion in the 1790s. Despite popular perceptions about the
decline of U.S. textile manufacturing in the face of for-
eign competition, the industry remains one of the larg-
est, most diverse, and most dynamic segments of the
U.S. manufacturing sector. Shipments from the approxi-
mately 6,000 establishments in the textile industry
reached a record $70 billion in 1992, and industry em-
ployment was around 630,000. The industry has main-
tained a competitive position in the face of strong import
competition from lower wage textile-producing countries
by specializing in high-value items, launching successful
"Buy American" promotional campaigns, modernizing
mills to equip them with the latest technology, and adopt-
ing "quick response" and "just-in-time" manufacturing
strategies that permit the industry to respond rapidly to
changing demands in the important apparel and home
furnishings markets.
Textile manufacturing begins with the production or har-
vest of raw fiber. Fiber used in textiles can be harvested
from natural sources (e.g., wool, cotton) or manufac-
tured from regenerative cellulosic materials (e.g., rayon,
acetate), or it can be entirely synthetic (e.g., polyester,
nylon). After the raw natural or manufactured fibers are
shipped from the farm or the chemical plant, they pass
through four main stages of processing:
• Yarn production
• Fabric production
• Finishing
• Fabrication
In yarn production, natural fibers, predominantly cotton
and wool, are cleaned, carded and/or combed, and then
spun into yarn. Just over half of the total shipments of
synthetic and cellulosic fibers are shipped as staple—
short fibers similar to cotton or wool—which are spun in
a process similar to that used for cotton and wool. Some
of this volume is tow fibers, which are composed of
bundles of staple fibers. The balance comes from the
manmade fiber producer as filament yarn, strands of
filament twisted together slightly that may be used di-
rectly or, after having been further twisted to the desired
consistency, in throwing mills.
Fabric production, the second step, involves either weaving
or knitting. Broadwoven mills consume the largest portion of
textile fiber and produce the raw textile material from which
most textile products are made. Manufacturers of knit fabrics
also consume a sizable amount of yams. Knit fabrics are
generally classified as either weft knit (circular-knit goods) or
warp knit (flat-knit goods). About 10 percent of fiber is knitted
into fabrics such as jersey or into final products such as
hosiery, underwear, outerwear, and gloves, while a small
portion is woven into narrow fabrics such as ribbon and
belting. Knits are used to a lesser extent for home furnishings.
In addition to weaving and knitting, yams are also used
directly in the production of floor coverings in a process called
tufting. Narrow wovens, waddings, nonwovens, and rope and
cordage are used primarily in industrial applications.
Finishing represents the third step. Most broadwoven fabrics
retain the natural color of the fibers from which they are
made. Cotton fabrics at this stage are known as "gray
goods," and the synthetics are said to be woven in the
"greige." For most uses, these fabrics must undergo further
processing, which can include bleaching, printing, dyeing,
mechanical finishing, preshrinking, and shaping. Many dif-
ferent textures can also be obtained through the application
of resins and sizings and the use of high temperature and
pressure. Finishing is important mainly in cotton and syn-
thetic production. For most wool products and some man-
made and cotton products (e.g., gingham), the yam is dyed
before weaving; thus, the pattern is woven into the fabric.
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Finally, the finished cloth is fabricated into a variety of
apparel and household and industrial products. The sim-
pler of these products, such as bags, sheets, towels,
blankets, and draperies, often are produced by the textile
mills themselves, but apparel or more complex house-
wares are usually fabricated by the cutting trades.
1.1.1 Textile Facilities
Textile facilities range from small, family-owned operations
using older, traditional manufacturing processes to huge
integrated mills operating the latest in textile machinery
and equipment. The industry includes a diverse, frag-
mented group of establishments that produce and/or
process textile-related products (thread, yarn, fabric) for
further processing into apparel, home furnishings, and
industrial goods.
Textile establishments receive and prepare fibers;
transform fibers into yarn, thread, or webbing; convert
the yam into fabric or related products; and dye and
finish these materials at various stages of production.
Many textile facilities also produce final consumer prod-
ucts (e.g., thread, yam, bolt fabric, hosiery, towels,
sheets, carpet), while the rest produce transitional prod-
ucts for use by other establishments in the textile indus-
try and by establishments classified in the apparel or
other industries.
Table 1-1 shows the structure of the textile industry by
Identifying the number of establishments in each three-digit
standard industrial classification (SIC) code category. This
breakdown illustrates the diversity of the industry. The
approximately 6,000 facilities fall into the following major
categories:
• Yam and thread mills
• Broadloom mills
• Narrow fabric mills
• Knitting mills
• Textile finishing
• Carpet and rug mills
• Miscellaneous textile products
The process of converting raw fibers into finished ap-
parel and nonapparel textile products is complex; thus,
most textile mills specialize. Little overlap occurs be-
tween knitting, narrow weaving, and broad weaving, or
between manmade, cotton, and wool fabric production.
A notable exception is the more than 300 integrated
companies that combine spinning and weaving in their
operations. Many of these companies buy or sell yarn in
the merchant market, but their own weaving operations
consume most of the yarn they spin. Even these large
integrated companies, however, do not normally con-
duct their own finishing operations. This necessitates an
Table 1-1. Number of Establishments in the Textile Industry
by Three-Digit SIC Code (1)
Total
SIC
Industry
Number
221 Broadloom mills—cotton
222 Broadloom
mills—manmade fibers,
including silk
302
418
5.2
7.2
223
224
225
226
227
228
229
Broadloom mills— wool
Narrow fabric mills
Knitting mills
Textile finishing, except wool
Carpets and rugs
Yarn and thread mills
Miscellaneous textile goods
Total
118
265
2,028
716
428
621
940
5,836
2.0
4.5
34.8
12.3
7.3
10.6
16.1
100.0
extensive textile finishing industry, comprising approxi-
mately 700 finishing and dyeing mills.
In some cases, fabric producers are vertically integrated
into the manufacture of textile products such as knit ho-
siery and knit apparel, carpets and rugs, tire cord, and rope
and cordage. Most woven fabrics destined for apparel and
home furnishings are further dyed and finished before the
cut-and-sew operations, in which the finished products are
manufactured. As noted, however, specialized dye and
finish houses perform most of this work. Carpet producers
are almost all integrated backward into yarn manufactur-
ing, adhesive formulation, and finishing. Du Pont and Mon-
santo, for example, manufacture fibers, carpeting, and
some of the chemicals used in carpet finishing.
1.1.1.1 Geographic Distribution
The textile industry is geographically concentrated in
the South- and Mid-Atlantic regions, based partly on
historical considerations. The industry developed first
in the Northeast and grew southward because of the
region's prominence in cotton production. Although
synthetics have replaced cotton as the primary raw
material in recent years, the Southeast continues to
dominate the U.S. textile industry. Major concentra-
tions of facilities are found in North Carolina, South
Carolina, Georgia, Alabama, Tennessee, and Virginia,
although certain segments of the industry are concen-
trated in other regions. For example, denim manufac-
ture is centered in the Southeast, while a considerable
amount of fabric dyeing and finishing takes place in
New York, New Jersey, and the New England states.
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1.1.1.2 Industry Concentration
Natural fibers tend to be shipped directly to textile mills
with little preparation or processing of the fibers. For the
most part, independent manufacturers perform the fiber
preparation and yarn spinning, although numerous large
integrated mills exist, and many separate yarn mills are
affiliated with larger textile conglomerates. Chemical
companies produce manmade fibers, and production in
this segment tends to be highly concentrated among a
small number of firms. According to a recent market
report on textiles, the U.S. manmade fiber industry con-
sists of over 100 companies operating approximately
150 plants, although only about a dozen are major
producers (2). The top six companies—Du Pont,
Hoechst Celanese, BASF, Allied-Signal, Monsanto, and
Amoco—account for approximately 80 percent of pro-
duction of manmade fibers. The dominant firms tend
to fall into one of the following categories: 1) large,
multiproduct chemical companies, 2) highly integrated
petrochemical companies, or 3) widely diversified indus-
trial firms with large chemicals- or materials-related seg-
ments (2). Approximately 60 percent of U.S. producers
specialize in olefin fiber production, while the remaining
market segments are controlled by a small number of
firms. In acrylic, modacrylic, and rayon, for example,
three firms account for all U.S. production. In acetate
fiber and spandex, two firms account for 100 percent of
U.S. output.
1.1.1.3 Research and Development
In the textiles industry, product development and inno-
vation are vital. Success in the industry has always
hinged on the ability of producers to innovate. Firms
constantly introduce new fibers and are always trying to
enhance and improve existing fibers (performance, aes-
thetics, blendability). The technical complexity of current
fiber formulations and the role of proprietary knowledge
account for the high degree of specialization in a rela-
tively narrow range of product segments. Research and
development (R&D) expenditures for large manmade
fiber producers range from 4 to 10 percent, which is high
compared with chemical industry standards (2).
1.1.1.4 Economies of Scale
Economies of scale in textile manufacturing are signifi-
cant and limit entry into the market. The cost of a new
fiber plant, for example, is approximately $100 million.
Costs of raw materials are frequently volatile and typically
account for 50 to 60 percent of the cost of the finished
product. To hedge against supply shocks and to secure
supply, many producers are vertically integrated back-
ward into chemical intermediates (and in the case of
companies such as Phillips, Amoco, DuPont, and
Conoco, all the way to crude oil). Forward integration
into apparel and product manufacture (e.g., carpeting)
also is not uncommon.
1.1.1.5 Capital Investment
The textile industry spends 4 to 6 percent of sales on
capital expansion and modernization, down from the 8
to 10 percent it averaged during the expansionary phase
of the 1960s and 1970s. Most recent capital expenditure
has paid for mill modernization and factory automation.
Industry also reports spending more than $25 million
each year on pollution and safety controls (2).
1.1.1.6 Merger Activity
In recent years, overcapacity and slower growth in some
market segments have made facility rationalization a top
priority. In the late 1980s and early 1990s, the market
experienced a significant reduction in capacity. Present
capacity appears to be in balance as demonstrated by
the high utilization rates recorded even during the
1990-1991 recession.
1.1.2 Machinery
Textile manufacturing encompasses four different stages
of production, and specialized machinery and equipment
is used at each stage. The following sections discuss
each of these stages of production:
• Preparation of fiber (natural) or fiber manufacturing
(manmade).
• Conversion of fiber into yarn (spinning).
• Manufacturing of textiles from yarn (weaving and
knitting).
• Coloring and finishing of textiles.
1.1.2.1 Fiber Preparation: Natural Fibers
As described in Section 1.1.3, two general categories of
fiber are used in textile manufacturing: natural (e.g.,
wool, cotton) and manmade, which includes cellulosic
(e.g., rayon, acetate) and synthetic (e.g., polyester, ny-
lon). Natural fibers must be opened, blended, carded
and/or combed, and drafted before spinning. Manmade
fibers are often shipped as staple (similar in length to
natural fibers), which is ready for spinning, or as filament
yarn, which may be used directly or following further
shaping or texturizing.
The following describes the main steps used for proc-
essing wool and cotton. Although equipment used for
cotton is designed somewhat differently from that used
for wool, the machinery operates in essentially the same
fashion:
• Opening/Blending: Suppliers deliver natural fibers .to
the spinning mill in compressed bales. The fibers must
be sorted based on grade, cleaned to remove particles
-------
of dirt, twigs, and leaves, and blended with fibers from
different bales to improve the consistency of the fiber
mix. Sorting and cleaning is performed in machines
known as openers. The opener consists of a rotating
cylinder, equipped with spiked teeth or a set of
toothed bars. These teeth pull the unbaled fibers
apart, fluffing them while loosening impurities. Be-
cause the feed for the opener comes from multiple
bales, the opener blends the fibers as it cleans and
opens them.
• Carding: Tufts of fiber from the blending and opening
operation are conveyed by air stream and fed to a
carding machine, which transports the fiber over a
belt equipped with wire needles. A series of rotating
brushes rests on top of the belt. The different rotation
speeds of the belt and the brushes cause the fibers
to tease out and align into thin, parallel sheets. Many
shorter fibers, which would weaken the yarn, are
separated out and removed. A further objective of
carding is to better align the fibers to prepare them
for spinning. The sheet of carded fibers is removed
through a funnel into a loose ropelike strand called a
sliver. Opening, blending, and carding are sometimes
performed in integrated carders that accept raw fiber
and output carded sliver.
• Combing: Combing is similar to carding except the
brushes and needles are finer and more closely
spaced. Several card slivers are fed to the combing
machine and removed as a finer, cleaner, and more
aligned comb sliver. In the wool system, combed
sliver is used to make worsted yarn, while carded
sliver is used for woolen yarn. In the cotton system,
the term combed cotton applies to the yarn made
from combed sliver. Worsted wool and combed cotton
are finer than yam that has not been combed be-
cause of the higher degree of fiber alignment and
further removal of short fibers.
• Drawing: Several slivers are combined and fed to a
machine known as a drawing frame. The drawing
frame contains several sets of rollers that rotate at
successively faster speeds. As the slivers pass
through, they are further drawn out and lengthened,
to the point where they may be five to six times as
long as they were originally. During drawing, slivers
from different types of fibers (e.g., cotton and poly-
ester) may be combined to form blends.
• Drafting: Drafting, which takes place on the roving
frame, stretches the yarn further. This process im-
parts a slight twist as it removes the yarn and winds
it onto a rotating spindle. The roving, as it is now
called, is about eight times the length and one-eighth
the diameter of the sliver, or approximately as wide
as a pencil. Following drafting, the rovings may be
blended with other fibers before being processed into
woven, knitted, or nonwoven textiles.
• Spinning: The rovings produced in the drafting step are
mounted onto the spinning frame, where they are set up
for spinning. The yam is first fed through another set of
drawing rolls, which lengthen and stretch it still further. It
is then fed onto a high-speed spindle by a guide that
travels up and down the spindle. The difference in speed
of travel between the guide and the spindle determines
the amount of twist imparted to the yam.
1.1.2.2 Fiber Manufacture: Manmade Fibers
Manmade fibers (both synthetic and cellulosic) are
manufactured by processes that simulate or resemble
the manufacture of silk (i.e., forcing a liquid through a
small opening where the liquid solidifies to form a con-
tinuous filament). Various shapes of solid and hollow
fiber can be produced by using different shaped spin-
nerettes. The three main methods of fiber manufacture
are described below:
• Wet spinning: In wet spinning, the polymer used to
form the fiber is dissolved in solution. The solution is
forced under pressure through an opening into a liq-
uid bath in which the polymer is insoluble. As the
solvent is dissipated in the bath, the fiber forms. Wet
spinning produces rayon, acrylic, and modacrylic.
• Dry spinning: Dry spinning uses a solvent that evapo-
rates in air. The dissolved polymer is extruded
through the spinnerette into a chamber of heated air
or gas, the solvent evaporates, and the fiber forms.
The solvent is generally recovered for reuse. Acrylic
is produced by dissolving the polymer in dimethyl
formamide before dry spinning. Other fibers formed
by dry spinning include acetate, triacetate, spandex,
and aramid.
• Melt spinning: Some polymeric fibers are spun by melt-
ing the polymer to a liquid state. The liquid is forced
through the spinner opening under pressure and cooled
by a jet of air to form the filament. Nylon can be spun
by melting nylon polymer chips in a melt-extruder, a
long heated cylinder that contains a rotating screw. The
chips are melted as they travel the length of the heated
zone of the tube, pumped to the spinerettes, and ex-
truded into a cold air stream. Melt spinning requires no
chemical reactions and no solvent recovery system. In
addition to nylon, polyester, olefin, and glass can also
be produced by melt spinning.
Following spinning, the manmade fibers are drawn to
align and orient the polymer molecules and strengthen
the filament. Manmade filaments may then betexturized
to give them spunlike properties. Texturizing uses curl-
ing, crimping, and tangling apparatuses to give straight
rodlike filament fibers the appearance, structure, and
feel of natural fibers.
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1.1.2.3 Yarn Spinning
Yarns are classified as either spun yarns or filament yarns:
• Spun yams: Spun yarns are formed from staple-
length fibers. Natural fibers are harvested as staples,
while manmade fibers may be cut to staple length for
the purpose of spinning. Manmade staple may be
produced in lengths suitable for processing on wool-
or cotton-system machinery. Yarn spinning is basi-
cally an extension of the preparation steps described
above for natural fibers. Additional twisting ortexturiz-
ing of the yarn may occur, or multiple yarns may be
twisted together to form plied yams. Plying takes
place on a machine similar to a spinning frame. Two
or more yarns pass through a pair of rollers and onto
a rotating spindle. The yarn guide positions the yarn
onto the spindle and assists in applying twist. Plied
yarns may be plied again to form thicker cords, ropes,
and cables.
• Filament yarns: Yarns are produced from filament
fibers in a process known as throwing. In the throwing
mill, the filament fibers are wound onto bobbins and
placed on a twisting machine. Manmade filaments
require additional drawing and are processed in an
integrated drawing/twisting machine.
1.1.2.4 Manufacturing of Textiles From Yarn
The major methods for .fabric manufacture are weaving,
knitting, and tufting. These are described in turn below.
Weaving
Weaving is performed on looms. The major components
of the loom are the warp beam, heddles, harnesses,
shuttle, reed, and takeup roll. The warp beam is a metal
cylinder that holds the warp yarns and feeds them into
the cloth. Heddles separate and guide the warp yarns,
allowing some to be raised and others lowered, while
the harnesses raise and lower the heddles. The shuttle
carries the fill yarns and inserts them into the weave.
The reed packs the fill yarns, and the takeup roll holds
the woven cloth.
Warp yarns are wound onto the beam from packages
mounted on creels, in a process known as beaming. The
warp yarns normally pass through a sizing solution on
route from the creel to the beam. Sizing protects the
yarn against snagging or abrasion that could occur dur-
ing weaving. The process of applying size to the warp
yarn is known as slashing.
The wound beam is mounted in the loom. The yarns are
passed through eye holes in the heddles, which hang
vertically from the harnesses. The weave pattern deter-
mines which harness controls which warp yarns, and the
number of harnesses used depends on the complexity
of the weave.
In a shuttle loom, the filling yarn is wound onto a quill,
which in turn is mounted in the shuttle. The shuttle is
normally pointed at each end to allow passage through
the shed (i.e. the vertical space between the raised and
unraised warp yarns). As the shuttle moves across the
loom laying down the fill yarn, the reed (which resembles
a comb) presses or beets the fill yarn into the weave.
Conventional shuttle looms can operate at speeds of
about 150 to 160 picks per minute. Several types of
shuttleless looms have been developed that operate at
higher speeds and reduced noise levels. Shuttleless
looms use different techniques to transport the fill yarns
faster across the shed, but regardless of the technique
used, they all carry a cut piece of fill yarn, rather than a
continuous piece:
• Water-jet looms: Water-jet looms transport the fill
yarn in a high-speed jet of water and can achieve
speeds of 400 to 600 picks per minute. Water jets
can handle a wide variety of fiber and yarn types and
are widely used for apparel fabrics.
• Air-jet looms: Air-jet looms use a blast of air to move
the fill yarn and can operate at up to 320 picks per
minute. These looms are limited in the types of filling
yarns they can handle.
• Rapier looms: Rapier looms use two thin wire rods
to carry the fill yarn and can operate at a speed of
510 picks per minute. Rapiers are used mostly for
spun yarns and are widely used for cotton and
woolen/worsted fabric. In a double rapier loom, two
rods move from each side and meet in the middle.
The fill yarn is carried from the rod on the fill side
and handed off to the rod on the finish side of the
loom.
• Projectile looms: Projectile looms use a projectile to
carry the fill yarn across the weave.
These shuttleless looms have been replacing the tradi-
tional fly-shuttle loom in recent years. By the end of
1989, shuttleless looms represented 54 percent of all
looms installed, up from 15 percent in 1980.
Knitting
In knitting, the fabric is formed through the interlocking
of one or more sets of yarns through a set of loops.
Knitting is performed using either weft or warp proc-
esses. In weft (or filling) knitting, one yarn is carried back
and forth and under needles to form a fabric. Yarns run
horizontally in the fabric, and connections between
loops are horizontal. In warp knitting, a warp beam is set
into the knitting machine. Yarns are interloped to form
the fabric, and the yarns run vertically while the connec-
tions are on the diagonal. Several different types of
machinery are used in both weft and warp knitting.
-------
• Weft knitting: Weft knitting machines can produce both
flat and circular fabric. Circular machines produce
mainly yardage but may also produce sweater bodies,
pantyhose, and socks. Flatbed machines knit full gar-
ments and operate at much slower speeds. The simplest,
most common filling knit fabric is single jersey. Double
knits are made on machines with two sets of needles.
All hosiery is produced as a filling knit process.
• Warp Knitting: Warp knitting represents the fastest
method of producing fabric from yams. Fabric is pro-
duced in sheet or flat form using one or more sets of
warp yams. The yarns are fed from warp beams to a
row of needles extending across the width of the ma-
chine. Tricot machines use a single set of spring-beard
or compound knitting needles, while Raschel machines
use one or two sets of vertically mounted latch needles.
Tufting
Tufting is the process of inserting additional yarns into
fabric to create a pile fabric. The substrate fabric can range
from a thin backing to heavy burlap-type material and may
be woven, knitted, or web. In modem tufting machines, a
set of hollow needles carries the yam from a series of
spools held in a creel and inserts the yam through the
substrate cloth. As each needle penetrates the cloth, a
hook on the underside forms a loop by catching and
holding the yam. The needle is withdrawn and moves
forward, much like a sewing machine needle. Patterns
may be formed by varying the height of the tuft loops. To
make cut-loop pile, a knife is attached to the hook and the
loops are cut as the needles are retracted. Tufting is used
for apparel fabrics, upholstery, and blankets, although
most tufting machines are used for carpeting. Well over 90
percent of broadloom carpeting is made by tufting, and
modem machines can stitch at rates of over 800 stitches
per minute, producing some 650 square yards of broad-
loom per hour.
1
)
1.1.2.5 Coloring and Finishing
Most manufactured textiles are shipped from textile mills
to commission dyeing and finishing shops (for further proc-
essing in integrated mills) for final coloring or finishing.
Alternatively, dyers and finishers may purchase gray
goods from mills for conversion to finished textiles. The
finisher then sells the piece goods to apparel, furnishing,
and industrial textile product manufacturers. A wide range
of equipment is used for textile dyeing and finishing.
Dyeing
As described elsewhere in this manual, textiles are dyed
using both continuous and batch processes, and dyeing
may take place at any of several stages of the manufac-
turing process (i.e., stock, tow, yarn, fabric, garment).
Table 1-2 describes the main types of dyeing machines
in use in the U.S. industry, indicating the stage of process-
ing at which each may be used, whether they are de-
signed for batch or continuous operation, the machine
capacities (width of fabric, weight of goods), as well as
descriptions, advantages, and disadvantages. Figure
1-1 diagrams each of these machine types. In terms of
overall volume, the largest amount of dyeing is per-
formed using beck and jig equipment.
Printing
Fabrics are printed with color and patterns, using a
variety of techniques and machine types. The major
types of printing are described below:
• Direct printing: In direct printing, a large cylindrical
roller picks up the fabric, and smaller rollers contain-
ing the color are brought into contact with the cloth.
The smaller rollers are etched with the design, and
the number of rollers reflects the number of colors.
Each smaller roller is supplied with color by a fur-
nisher roller, which rotates in the color trough, picks
up color, and deposits it on the applicator roller. Doc-
tor blades scrape excess color off the applicator
roller so that only the engraved portions carry the
color to the cloth. The cloth is backed with a rub-
berized blanket during printing, which provides a
solid surface to print against, and a layer of gray
cloth is .used between the cloth and the rubber
blanket to absorb excess ink.
• Warp printing: Warp printing places a pattern on the
warp yarns prior to weaving. Fill yarns are white or
yellow and carry no pattern.
• Discharge printing: Discharge printing is performed
on piece-dyed fabrics. The patterns are created
through removal, rather than addition, of color, hence
most discharge printing is done on dark backgrounds.
The dyed fabric is printed using discharge pastes,
which remove background color from the substrate
when exposed to steam. Colors may be added to the
discharge paste to create colored discharge areas
against the background.
• Resist printing: Resist printing encompasses several
hand and low-volume methods in which the pattern
is applied by preventing color from penetrating cer-
tain areas during piece-dyeing. Examples of resist
printing methods include batik, tie-dyeing, screen
printing, and stencil printing.
• Jet printing: Jet printing, used mainly for carpet, ap-
plies dye to the substrate fabric in continuous
streams, using applicator jets.
• Heat-transfer printing: In heat-transfer printing, the
pattern is first printed onto a special paper substrate.
The paper is then positioned against the fabric and
subjected to heat and pressure. The dyes are trans-
ferred to the fabric via sublimation.
-------
Table 1-2. Comparison of Dyeing Equipment (3)
Capacity
Machine Material
Type Processed
Width
Weight
Description, Advantages, Disadvantages
Stock
Skein
Dope
Beck
Jet
Beam
Jig
Paddle
Fiber
Package Yarn
Yarn
Polymer melt-
dyed prior to
filament
formation
Fabric
Fabric
Fabric
Fabric
Rope
2m
Fabric or product —
Garment Garments
(rotary)
Chain Yarn
(tow)
Continuous Fabric
500 kg
550kg
100kg
Continuous
900kg
Rope 500 kg
Up to 5m 1,000kg
250kg
100kg
500 kg
Continuous
Up to 3 m Continuous
Fiber is dyed inside perforated tubes. Same machine can be used for
package and beam dyeing. Large quantities of dyed fiber can be blended
for color consistency.
Yarn is stationary, bath is pumped through. Same machine can be used for
beam or stock dyeing.
Yarn is dyed in hanks. Used for bulky acrylic and wool yams.
Pigments are added to polymer before extrusion into fiber.
Very versatile—can be used almost universally. Good for repair work.
Causes substantial mechanical working of goods. Can cause cracks in
delicate, lightweight goods (e.g., nylon and acetate).
Capable of high pressure and temperature. Fabric is handled gently. Fabric
and bath are both in motion during dyeing.
Fabric is handled flat, thus reducing creases and cracks in delicate goods.
Optimum for lightweight, wide, and delicate goods. Fabric is stationary, bath is
pumped through. Same machine can be used for stock or package dyeing.
Fabric is handled flat, thus reducing creases and cracks. Does not run
disperse dyes very well. Too much tension for weft knits.
For products such as hosiery, rugs, etc.
Garments are dyed before cutting and sewing.
Used to dye yarns continuously.
Best economics for long runs. Several types of fixing methods include
steam, chemical reactions, thermofix, and cold batch methods. Not effective
for general repair work. The only type of dye machine that can run
pigments. Too much tension for knits.
Finishing
Finishing encompasses any of several processes per-
formed on fiber, yam, or fabric to improve its appearance,
texture, or performance. Physical finishing methods include:
• Bulking and texturizing: Thermoplastic manmade fibers
are often permanently heat-set after drawing and ori-
entation. Thermoplastic yarns also can be texturized
to give loft and bulkiness.
• Optical finishing: Luster can be added to yarns by
flattening or smoothing the surfaces under pressure.
This can be achieved by beating the fabric surface
or passing the fabric between calendering rolls. The
luster effect can be increased if the rolls are scribed
with closely spaced lines to reinforce light scattering.
• Brushing and napping: Brushing and napping decrease
the luster of fabrics by roughening or raising the fiber
surface. These processes involve the use of wires or
brushes that pull individual fibers.
• Softening: Calendering can be used to reduce surface
friction between individual fibers, thereby softening
the fabric structure and improving its feel.
• Shearing: Shearing is a process that removes sur-
face fibers by passing the fabric over a cutting blade
or a flame (singeing).
• Compacting: Compacting, which includes the Sanfo-
rizing process, compresses the fabric structure to
reduce stresses in the fabric. The fabric and backing
blanket are fed between a roller and a curved braking
shoe, with the blanket under tension. The tension on
the blanket is released after the fabric and blanket
pass the braking shoe. The compacting reduces the
potential for excessive shrinkage on laundering.
Chemical agents are also applied in textile finishing to
impart a variety of characteristics, including:
• Optical finishes: Finishes added to either brighten or
deluster the textile.
• Absorbent and soil release finishes: Finishes that alter
surface tension and properties to increase water
absorbency or improve soil release,
• Softeners and abrasion-resistant finishes: Finishes
added to improve feel or increase the ability of the
textile to resist abrasion and tearing.
-------
Typa of Typical Configuration
Machine Substrate Width Capaclty/Llmltatfons/Advantages
Machine
Type of Typical Configuration
Substrate Width Capacity/Limitations/Advantages
Stock Fiber
500 kg Fiber is dyed inside of
perforated tubes.
Same machine can be used
for package and beam dyeing.
Large quantities of dyed fiber
can be blended for color
consistency.
Perforated
Cylinder
Fiber'inside
Package Yam
550 kg Yarn is stationary, bath is
pumped through.
Same machine can be
used for beam or stock
dyeing.
Yarn
Package
Dye liquor is
pumped through
Dye liquor
is pumped
through
Stock Dyeing
Package Dyeing
Type of
Machine Substrate
Typical Configuration
Width Capacity/Limitations/Advantages
Machine
Type of
Substrate
Width
Typical Configuration
Capacity/Limitations/Advantages
Skein
Yam
100 kg Yam is dyed in hanks.
Used for bulky acrylic
and wool yarns.
Dope Polymer melt ' Continuous Pigments are added
prior to yarn polymer before
formation. extrusion into fiber.
Manifold Dye liquor is pumped
through manifold as
f
Yam /
Hank /
-> 7/_
Dye Liquor
T
A
\j
\ yam rots
\
— x"^
Skein Dyeing (end view)
Figure 1-1. Dyeing machinery.
-------
Type of Typical Configuration
Machine Substrate Width Capacity/Llmitationsi/Advantages
Beck Fabric Rope 9001
Very versatile—can be used
almost universally.
Good for repair work.
Causes substantial
mechanical working of goods.
Can cause creases and
cracks in delicate, lightweight
goods (e.g., nylon, acetate).
Beck Dyeing (end view)
Type of
Machine Substrate Width
Typical Configuration
Capacity/Limitations/Advantages
Beam Fabric Up to 5 1,000kg Fabric is handled flat, thus
meters reducing creases and
cracks in delicate goods.
Optimum for lightweight,
wide, and delicate goods.
Fabric is stationary, bath is
pumped through.
Same machine can be
used for stock or package
dyeingi.
Beam Dyeing
Type of
Machine Substrate Width
Typical Configuration
Capacity/Limitations/Advantages
Jet
Fabric Rope 500 kg
Capable of high pressure
and temperatures.
Fabric is handled gently.
Fabric and bath both are
in motion.
Dye liquor is pumped, thus
transporting fabric through
the dyeing venturi tube
Venturi Tube
Dye Liquor
Type of
Machine Substrate Width
Jet Dyeing
Typical Configuration
Capacity/Limitations/Advantages
Jig
Fabric
2 meters 250 kg Fabric is handled flat
reducing creases and
cracks.
Does not run disperse
dyes very well.
Too much tension for weft
knits.
Let-off Roll
Take-up Roll
Jig Dyeing (end view)
Figure 1-1. Dyeing machinery (continued).
-------
Typa of Typical Configuration
Machtnt Substrate Width Capacity/Limitations/Advantages
Paddle
Fabric or
Products
100kg For products such as
hosiery, rugs, etc.
Machine
Garment
(Rotary)
Type of Typical Configuration
Substrate Width Capacity/Limitations/Advantages
Products
(garments)
500 kg Garments are dyed
cutting and sewing.
Dye Liquor
Rotary Garment Dyeing
Paddle Dyeing
Machine
Type of
Substrate Width
Typical Configuration
Capacity/Limitations/Advantages
Continuous Fabric
Typi of Typical Configuration
Machln« Substrate Width Capacity/Limitations/Advantages
Chain
(Tow)
Yam
Continuous Used to dye yams
continuously.
Up to 3 Contin- Best economics for long
meters uous runs. Poor economics for
short runs.
Several types of fixing
methods include steam,
chemical reactions,
thermofix, and cold batch
methods.
Not effective for general
purpose repair work.
The only type of dyeing
machine which can run
pigments.
Too much tension for knits
may be a problem.
Dry
Dye Pad chem Pad
Steam or
Thermofix
Wash
Continuous Yarn Dye
Dye Pad chem Pad
Steam or
Thermofix
Wash
Continuous Dyeing
Figure 1-1. Dyeing machinery (continued).
10
-------
• Stiffening and weighting agents: Include temporary
finishes added to improve processability of textiles as
well as permanent sizes that stiffen the fabric.
• Crease-resistant and stabilizing finishes: Melanine or
urea-formaldehyde resins applied to cellulosic fabrics
to improve crease resistance and wrinkle recovery.
• Other finishes: Include photoprotective agents, antioxi-
dants, oil and water repellents, antistatic treatments,
biological protectants, and flame retardants.
Many chemical finishes are applied using padding ma-
chines, which pass the fabric through the finishing solu-
tion, under a guide roller, and between two padding rolls.
The rolls remove excess liquid before the fabric is trans-
ported to a steaming or washing and drying machine.
The backfilling machine is a variant of the padding ma-,
chine that applies the finishing solution to only one side
of the fabric.
1.1.3 Fiber
Textile fibers are categorized into two principal groups,
natural and manmade. Natural fibers (cotton, wool,
hemp, linen, jute, silk) are the products of agriculture. Of
these, only cotton and wool are of commercial impor-
tance in the United States; silk, hemp, and jute are used
but in insignificant amounts. During the past several
decades, the proportion of cotton and wool textiles has
decreased and the proportion of manmade fibers has
increased. Manmade fibers now represent the major
raw material source for the industry. In 1989, manmade
fiber accounted for 68 percent (8.8 billion pounds) of
total textile mill fiber consumption of 12.9 billion pounds.
Manmade fibers encompass both purely synthetic ma-
terials (e.g., nylon, polyester), derived from petrochemi-
cals, and regenerative cellulosic materials (e.g., rayon,
acetate), manufactured from wood fibers. Both types of
manmade fibers are typically extruded into continuous
. filaments, which may then undergo treatment to impart
texture to the fibers. The continuous filaments may be
spun into yarn directly, or they may be cut into staple
length and then spun in a process resembling that used
for wool or cotton.
1.1.4 Products
The U.S. textile industry produces a diverse mix of prod-
ucts including woven and coated fabrics, knit goods, fin-
ished fabrics, carpets and rugs, yarn and thread, and
miscellaneous textile products. It is convenient to consider
the industry in terms of the categorization scheme followed
in the U.S. government's Standard Industrial Classification
(SIC) Manual. The textile industry as a whole is assigned
the 2-digit SIC code 22, under which are nine three-digit
industry groups and 23 four-digit industries. A total of 90
different product classes are produced. These industry
categorizations are described further in Table 1-3.
Value of shipments data for the textile industry is shown
in Table 1-4.
1.2 Overview of Pollutants and Waste
Streams
Textile processing generates many waste streams, in-
cluding water-based effluent as well as air emissions,
solid wastes, and hazardous wastes. The nature of the
waste generated depends on the type of textile facility,
the processes and technologies being operated, and the
types of fibers and chemicals used. This section pre-
sents information on the sources and amounts of air and
water emissions and solid and hazardous wastes gen-
erated, as well as pollution prevention strategies for each.
1.2.1 Air Pollutants
Most processes performed in textile mills produce at-
mospheric emissions. Gaseous emissions have been
identified as the second greatest pollution problem (after
effluent quality) for the textile industry (6)^ Speculation
concerning the amounts and types of air pollutants emit-
ted from textile operations has been widespread (7-9),
but, generally, air emissions data for textile manufactur-
ing operations are not readily available. Most published
data are based on mass-balance calculations, not direct
measurements (10, 11).
Air pollution is the most difficult type of pollution to
sample, test, and quantify in an audit. Measurement
techniques such as direct reading tubes and gas chro-
matography (GC)Anass spectrometry have been used
recently to collect more reliable data (12,13). Continued
collection of air emissions data from textile operations
will result in better definitions of industry norms. Efforts
are now underway to establish a reliable set of emissions
factors for textiles (13, 14); however, no set is currently
available that can be recommended for audit purposes.
1.2.1.1 Sources
Air emissions can be classified according to the nature
of their sources:
• Point sources: Specific discharge points, such as
stacks or vents, that are intended to be the point of
atmospheric release for emissions.
• Fugitive sources: Sources for more general-atmos-
pheric emissions such as those that occur through
evaporation, leaks, and spills.
Point sources of air pollutants include:
• Boilers: Boilers are one of the major point sources of
air emissions in the textile industry. Primarily because
of emissions of nitrogen and sulfur oxides from boil-
ers, most textile plants are likely to be classified as
major sources of air toxics under the NESHAPs of
11
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Table 1-3. Textile Industry Categorization (4, 5)
SIC Industry Name Description
221 Broadwoven fabric mills, cotton
2211 Broadwoven fabric mills, cotton
1990 establishments count: 302
Establishments primarily engaged in weaving fabrics more than 12 inches in width,
wholly or chiefly by weight of cotton. Establishments primarily engaged in weaving or
tufting carpet and rugs are classified in Industry 2273; those making tire cord and fabrics
are classified in Industry 2296; and those engaged in finishing broadwoven fabrics are
classified in Industry 2261.
222 Broadwoven fabric mills, manmade fiber and silk
2221 Broadwoven fabric mills,
manmade fiber and silk
1990 establishments count: 418
Establishments primarily engaged in weaving fabrics more than 12 inches in width,
wholly or chiefly by weight of silk and manmade fibers excluding glass.
Establishments primarily engaged in weaving or tufting carpet and rugs from these
fibers are classified in Industry 2273; those making tire cord and fabrics are classified
in Industry 2296; and those engaged in finishing manmade fibers and silk broadwoven
goods are classified in Industry 2262.
223 Broadwoven fabric mills, wool (including dyeing and finishing)
2231 Broadwoven fabric mills, wool
(including dyeing and finishing)
1990 establishments count: 118
Establishments primarily engaged in weaving fabrics more than 12 inches in width,
wholly or chiefly by weight of wool, mohair, or similar animal fibers; dyeing and finishing
all woven wool fabrics or dyeing wool, tops, or yarn; and those shrinking and sponging
wool for the trade. Establishments primarily engaged in weaving or tufting wool carpet
and rugs are classified in Industry 2273.
224 Narrow fabric and other smallwares mills: cotton, wool, silk, and manmade fiber
2241 Narrow fabric and other
smallwares mills: cotton, wool,
silk, and manmade fiber
1990 establishments count: 265
225 Knitting mills
2251 Women's full-length and
knee-length hosiery, except socks
1990 establishments count: 144
2252 Hosiery, not elsewhere classified
1990 establishments count: 414
2253 Knit outerwear mills
1990 establishments count 693
2254 Knit underwear and nightwear
mills
1990 establishments count: 61
2257 Weft knit fabric mills
1990 establishments count: 309
2258 Lace and warp knit fabric mills
1990 establishments count: 220
2259 Knitting mills, not elsewhere
classified
1990 establishments count: 73
Establishments primarily engaged in weaving or braiding narrow fabrics of cotton,
wool silk, and manmade fibers, excluding glass fibers. These fabrics are generally
12 inches or less in width in their final form but may be made initially in wider widths
that are specially constructed for cutting to narrower widths. Also included in this
industry are establishments primarily engaged in producing fabric-covered elastic
yarn or thread.
Establishments primarily engaged in knitting, dyeing, or finishing women's and misses'
full-length and knee-length hosiery (except socks), both seamless and full-fashion, and
panty hose. Establishments primarily engaged in knitting, dyeing, or finishing women s
and misses' knee-length socks and anklets are classified in Industry 2252.
Establishments primarily engaged in manufacturing elastic (orthopedic) hosiery are
classified in Industry 3842.
Establishments primarily engaged in knitting, dyeing, or finishing hosiery, not elsewhere
classified. Establishments primarily engaged in manufacturing women's full-length and
knee-length hosiery (except socks) and panty hose are classified in Industry 2251.
Establishments primarily engaged in manufacturing elastic (orthopedic) hosiery are
classified in Industry 3842.
Establishments primarily engaged in knitting outerwear from yarn or in manufacturing
outerwear from knit fabrics produced in the same establishment. Establishments
primarily engaged in hand knitting outerwear for the trade are included in this industry.
Establishments primarily engaged in knitting gloves and mittens are classified in
Industry 2259, and those manufacturing outerwear from purchased knit fabrics are
classified in Major Group 23.
Establishments primarily engaged in knitting underwear and nightwear from yarn or in
manufacturing underwear and nightwear from knit fabrics produced in the same
establishment. Establishments primarily engaged in manufacturing underwear and
nightwear from purchased knit fabrics are classified in Major Group 23. Establishments
primarily engaged in knitting robes are classified in Industry 2253.
Establishments primarily engaged in knitting weft (circular) fabrics or in dyeing or
finishing weft knit fabrics.
Establishments primarily engaged in knitting, dyeing, or finishing warp (flat) knit fabrics
or in manufacturing, dyeing, or finishing lace goods.
Establishments primarily engaged in knitting gloves and other articles, not elsewhere
classified. Establishments primarily engaged in manufacturing woven or knit fabric
gloves and mittens from purchased fabrics are classified in Industry 2381.
12
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Tabte 1-3. Texttte Industry Categorization (4, 5) (Continued)
SIC Industry Name Description
226 Dyeing and finishing textiles (except wool fabrics and knit goods)
2261
Finishers of broadwoven fabrics
of cotton
1990 establishments count: 268
2262
2269
Finishers of broadwoven fabrics
of manmade fiber and silk
1990 establishments count: 262
Finishers of textiles, not
elsewhere classified
1990 establishments count: 172
227 Carpets and rugs
2273 Carpets and rugs
1990 establishments count: 621
228 Yarn and thread mills
2281 Yarn spinning mills
1990 establishments count: 416
2282 Yarn texturizing, throwing,
twisting, and winding mills
1990 establishments count: 138
2284 Thread mills
1990 establishments count: 59
229 Miscellaneous textile goods
2295 Coated fabrics, not rubberized
1990 establishments count: 176
2296 Tire cord and fabrics
1990 establishments count: 14
2297 Nonwoven fabrics
1990 establishments count: 121
Establishments primarily engaged in finishing purchased cotton broadwoven fabrics, or
finishing such fabrics, on a commission basis. These finishing operations include
bleaching, dyeing, printing (roller, screen, flock, plisse), and other mechanical finishing,
such as preshrinking, calendering, and napping. Also included in this industry are
establishments primarily engaged in shrinking and sponging of cotton broadwoven
fabrics for the trade and chemical finishing for water repellency, fire resistance, and
mildew proofing. Establishments primarily engaged in finishing wool broadwoven fabrics
are classified in Industry 2231; those finishing knit goods are classified in Industry
Group 225; and those coating or impregnating fabrics are classified in Industry 2295.
Establishments primarily engaged in finishing purchased manmade fiber and silk
broadwoven fabrics, or finishing such fabrics, on a commission basis. These finishing
operations include bleaching, dyeing, printing (roller, screen, flock, plisse), and other
mechanical finishing, such as preshrinking, calendering, and napping. Establishments
primarily engaged in finishing wool broadwoven fabrics are classified in Industry 2231;
those finishing knit goods are classified in Industry Group 225I; and those coating or
impregnating fabrics are classified in Industry 2295.
Establishments primarily engaged in dyeing and finishing textiles, not elsewhere
classified, such as bleaching, dyeing, printing, and finishing of raw stock, yarn, braided
goods, and narrow fabrics, except wool and knit fabrics. These establishments perform
finishing operations on purchased textiles or on a commission basis.
Establishments primarily engaged in manufacturing woven, tufted, and other carpets
and rugs, such as art squares, floor mattings, needle punch carpeting, and door mats
and mattings, from textile materials or from twisted paper, grasses, reeds, coir, sisal,
jute, or rags.
Establishments primarily engaged in spinning yarn wholly or chiefly by weight of cotton,
manmade fiber, silk, mohair, or similar animal fibers. Establishments primarily engaged
in dyeing or finishing purchased yarns or finishing yams on a commission basis are
classified in Industry 2231 if the yarns are wool and Industry 2269 if they are of other
fibers. Establishments primarily engaged in producing specialty yarns or producing spun
yarns of other fibers are classified in Industry 2299.
Establishments primarily engaged in texturizing, throwing, twisting, winding, or spooling
purchased yarns of manmade fiber filaments wholly or chiefly by weight of cotton,
manmade fiber, silk, mohair, or similar animal fibers, or in performing such activities on
a commission basis. Establishments primarily engaged in dyeing or finishing purchased
yarns or finishing yarns on a commission basis are classified in Industry 2231 if the
yarns are wool and Industry 2269 if they are of other fibers. Establishments primarily
engaged in producing and texturizing manmade fiber filaments and yarns in the same
plant are classified in Industries 2823 or 2824.
Establishments primarily engaged in manufacturing thread of cotton, silk, manmade
fibers, wool, or similar animal fibers. Important products of this industry include sewing,
crochet, darning, embroidery, tatting, hand-knitting, and other handicraft threads.
Establishments primarily engaged in manufacturing thread of flax, hemp, and ramie are
classified in Industry 2299.
Establishments primarily engaged in manufacturing coated, impregnated, or laminated
textiles, and in the special finishing of textiles, such as varnishing and waxing.
Establishments primarily engaged in rubberizing purchased fabrics are classified in
Industry 3069, and those engaged in dyeing and finishing textiles are classified in
Industry Group 226 or Industry 2231.
Establishments primarily engaged in manufacturing tire cord and fabric of manmade
fibers, cotton, glass, steel, or other materials for use in reinforcing rubber tires,
industrial belting, fuel cells, and similar uses.
Establishments primarily engaged in manufacturing nonwoven fabrics (by bonding
and/or interlocking of fibers) by mechanical, chemical, thermal, or solvent means, or by
combinations thereof. Establishments primarily engaged in producing woven felts are
classified in Industry 2231, and those producing other felts are classified in Industry
2299.
13
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Table 1-3. Textile Industry Categorization (4, 5) (Continued)
SIC Industry Name Description
2288 Cordage and twine
1990 establishments count: 187
2299 Textile goods, not elsewhere
classified
1990 establishments count: 434
Establishments primarily engaged in manufacturing rope, cable, cordage, twine, and
related products from abaca (Manila), sisal, henequen, hemp, cotton, paper, jute, flax,
manmade fibers including glass, and other fibers.
Establishments primarily engaged in manufacturing textile goods, not elsewhere
classified, including linen goods, jute goods, felt goods, padding and upholstery filling,
and processed waste and recovered fibers and flock. Establishments primarily engaged
in processing textile fibers to prepare them for spinning, such as wool scouring and
carbonizing and combing and converting tow to top, are also classified here.
Establishments primarily engaged in manufacturing woven wool felts and wool haircloth
are classified in Industry 2231, and those manufacturing needle punch carpeting are
classified in Industry 2273. Establishments primarily engaged in manufacturing
embroideries are classified in Industry Group 229. Establishments primarily engaged in
sorting wiping rags or waste are classified in Wholesale Trade, Industry 593.
Table 1-4. Value of Shipments Data, 1987
Industry Group
Value (billions of
1987 dollars)
Yam and thread mills
Broadioom mills
Cotton
Manmade and silk
Wool
Narrow fabric mills
Knitting mills
Textile finishing, except wool
Carpets and rugs
Miscellaneous textile products
Total
10.1
14.7
5.5
8.1
1.0
1.1
13.7
7.2
10.0
6.5
63.5
the 1990 Clean Air Act Amendments. Air toxics, an
emerging issue for the textile industry, are discussed
in more detail in Section 2.2.3, 'Toxic Air Emissions."
• Ovens: Probably the most prevalent source of air
emissions in textile operations is high-temperature
drying and curing ovens. The highest levels of emis-
sions by far come from ovens used for coating op-
erations. In some cases, the solvent content of the
air in coating ovens can reach levels of several per-
cent. Also, lower levels of emissions come from heat-
setting and thermofixation, as well as drying and
curing ovens. Typical operating temperatures range
from 250°F to 400°F (see Table 1-5).
• Storage tanks: Typically, bulk storage tanks for textile
chemicals have open vents to allow equalization of
Table 1-5. Typical Operating Temperatures of Textile
Operations Contributing to Air Emissions
Operation
Operating Temperature
Drying
Curing of ordinary finishes
Thermofixation of dyes
Heatsetting
250°F-300°F
300°F-375°F
350°F-400°F
300°F-375°F
internal and external pressures. When the chemical is
drawn out of the tank, when air cools (e.g., at night), or
when the ambient atmospheric pressure rises, air is
forced into the tank. When the tank is filled, when
temperatures rise, or when the barometric pressure
falls, air is forced out of the tank. When the chemical
in the tank contains volatile components, these compo-
nents can contaminate the air inside of the tank. The
expelled air, therefore, constitutes an emission source.
Fugitive or area sources of air pollutants in textile opera-
tions include:
• Solvent-based cleaning activities: Solvents are used
widely for cleaning and maintenance in textile opera-
tions. Examples of solvent cleaning applications include
general facility cleanup and maintenance, implement
and parts cleaning, and print screen cleaning.
• Wastewater treatment systems: Aeration of secon-
dary activated sludge biological treatment lagoons
strips most volatile components of the mixed liquor,
and these are emitted from the waste treatment sys-
tem as a general area source. Volatile components
of spent processing baths (e.g., dye carriers, solvent
scours) as well as degradation products of these
components can reasonably be expected to strip and
emit during the treatment process; however, no public
data are available to confirm this assumption.
• Warehouses: Fabric stored in warehouses can emit
volatile emissions from process residues, especially
printing or dyeing residues, or finishing chemicals
that remain in the fabric. Formaldehyde residues
have caused the most problems for the industry, but
other residues, notably hydrocarbons from softeners
and wax water-repellent finishes, also can be present
in fabric and result in volatile emissions.
• Spills: Spills can emit volatile pollutants for years
and, therefore, should be cleaned up promptly. Spill
residues should be disposed of according to proper
protocol, which in some cases requires handling resi-
dues as hazardous waste.
14
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Common air pollutant emissions from ovens include
mineral oil and other vapors (12). Others include knitting
oils, fiber finishes, softeners, hydrocarbons, urea (from
continuous printing and thermofix dyeing of fiber-reac-
tive dyes), and volatile disperse dye carrier components
that are sorbed into the fabric during subsequent heat-
setting, drying, and curing (15, 16).
1.2.1.2 Indoor Air Pollution
In recent years, textile materials have been linked to
indoor air quality (IAQ) problems. Textile materials that
emit pollutants (primary emitters) as well as those that
sorb and reemit air pollutants jndoors (secondary emit-
ters) are a concern for the textile industry (14).
At this time, researchers are studying primary emissions
from the types of textile process residues listed below
(14, 17):
• Chemical finishes
• Dyeing process residues
• Assembly and fabrication residues
Primary emissions from textile materials can include
formaldehyde and amine odors. Formaldehyde is an
eye, mucous membrane, and skin irritant, and has been
shown to be carcinogenic. Emissions of formaldehyde
from textile resin-treated materials decrease approxi-
mately 50 percent during the first year of use and ap-
proximately 90 percent during the following 4 years.
Test procedures exist for determining primary emis-
sions, but other emissions are not well characterized or
commonly analyzed. Some chemical components from
the finishing process might survive through to exhaust
as primary emissions in the final product. In addition,
volatile chemical components of manmade polymers,
fiber finishes, and residues from dyeing and printing
might also exist in latent forms and degrade IAQ.
Various factors can affect a textile's ability to contribute
to IAQ problems: fiber cross-sectional shape, specific
surface area, yarn structure and tightness of weave for
pure textiles, and textile-containing product (TCP) as-
semblies (e.g., upholstered furniture with fiberfill).
In addition, some textiles are believed to sorb chemicals
from the surrounding atmosphere and later reemit these
chemicals, which degrades IAQ. Therefore, the sorp-
tion/reemission characteristics of textile materials also
are being studied. Knowledge of these characteristics
will facilitate (14, 17):
• Using textile group products in an appropriate man-
ner (i.e., compatible with other materials and end-use
requirements).
• Developing better purchasing specifications.
• Understanding synergisms in pollutant release.
« Understanding sorption/desorpft'on from textile surfaces.
• Modeling of workplace exposure.
Compounds commonly used for textile assembly include
adhesives, sealants, and cleaning solvents. All these
compounds can be sorbed and reemitted. Cross-media
contamination also causes air pollutants. For example,
storing textile products near sources of volatile organic
compounds can result in sorption and reemission.
Several tests have been conducted on air emissions
from drapery materials. Tables 1 -6 and 1 -7 list chemicals
identified during monitoring of emissions from drapery
materials and linings, respectively (18). Chemicals can
derive either from process residues or from materials
sorbed into the material during fabrication, storage, in-
stallation, or consumer use. A survey of finish chemical
components listed on material safety data sheets
(MSDSs) for typical commercial finishes includes a va-
riety of somewhat volatile materials that might be emit-
ted by the material (14). These chemicals are listed in
Table 1-8.
The U.S. Occupational Safety and Health Administration
,(OSHA) has proposed an IAQ rule that will affect 21
million workers and will require the development and
implementation of IAQ compliance programs (17). This
rule can be expected to enhance awareness of IAQ
issues in the workplace and focus further attention on
textile sorption and emission characteristics.
1.2.1.3 Pollution Prevention Strategies
Textile mills often have difficulty identifying critical air
pollutant issues and pollution prevention goals. In many
cases, pollution prevention strategies are not based on
the actual presence of air pollutants, but on linking
potential air emissions problems to the types of inputs
used. The kinds of audit data used to identify water
Table 1-6. Air Emissions From Drapery Materials (18)
Acetone
2,5-Dimethylfuran
Benzaldehyde
1,4-Dioxane
Benzene
Ethanol
Butanol
Methylene chloride
p-Xylene
Dimethyldisulfide
Decane
Toluene
Decenal
I,l,l-Trichloroethane
Dichlorobenzene
Trimethylbenzenes
1,2-Dichloroethane
m-Xylene
Chloroform
Tetrachloroethene
. plus 100 more volatile organic compounds (VOCs)
Table 1-7. Air Emissions From Drapery Linings (18)
Acetone
Chloroform
Decenal
Ethanol
Ethylmethylbenzenes
3-Hexanone
2-Methylfuran
Pyrollidine
Trichloroethene
Benzene
Decane
1 ,4-Dioxane
Ethyl acetate
Hexanes
Methylene chloride
Pyridinone
Toluene
m-Xylene
... plus 80 additional VOCs
15
-------
Table 1-8. Listed Chemicals From MSDSs for Textile
Finishing Agents (19)
Chemical Name
CASa Number
Acetone 67-64-1
Ethyl acetate 141-78-6
Ethytene glycol 107-21-1
Fatty glyceride-based softener NAb
Formaldehyde 50-00-0
Hydrocarbon wax emulsion (four reported) NA
Methanol 67-56-1
Methyihydrogen polysiloxane 63148572
Nonylphenolpolyethylene glycol ether 9016-45-9
2-Pentanone, 4-methyl- 108-10-1
Polyoxyethylated tridecyl alcohol 24938918
Proprietary materials NA
Residual monomers (acrylic) NA
Tetrachloroethylene 127184
Toluene 108883
Trielhanolamlne 102716
* CAS = Chemical Abstract Service.
bNA= not applicable.
(Section 1.2.2), solid (Section 1.2.3), and hazardous
wastes (Section 1.2.4) are not readily available for tex-
tile air emissions.
Strategies for preventing air pollutants are site specific,
but some of the main strategies are noted below. These
strategies also are discussed in more detail in sections
covering individual processes (e.g., finishing, dyeing):
• Design products that do not require volatile chemicals.
In particular, avoid specifying solvent-based (e.g.,
water-repellent) finishes unless absolutely necessary.
* Identify and quantify sources, if possible, by direct
measurement. If that is not possible, use MSDS in-
formation for input chemicals along with knowledge
of the process to estimate emissions. Prescreen and
test all chemicals to ensure quality using the protocol
described in Section 4.4, "Chemical Specialties."
• Optimize boiler operations. Although detailed discus-
sion of boiler operations and maintenance is beyond the
scope of this manual, boiler emissions are a main source
of pollution and must be addressed through optimization
as part of any pollution prevention program.
• improve solvent processing operations. Carefully se-
lect solvents. Use nonvolatile alternatives.
• Keep detailed (redundant tracking) records of all solvents
purchased, issued, reclaimed, reused, recovered, and
disposed of to facilitate emissions mass balances.
Use special monitoring procedures (direct reading
tubes) in work areas and ventilation stacks. Install
direct solvent dispensing machines wherever possi-
ble, and use the best equipment design and mainte-
nance procedures. Optimize capture efficiencies for
all air handling, exhaust, and ventilation operations.
• Prescreen fibers for volatile spin finishes, and de-
velop raw material specifications for finish content of
fibrous raw materials. A simple prescreening test in-
volves heating a large fabric sample in a laboratory
oven at the processing temperature (or higher). Vola-
tile spin finishes generally will be visible as gray
smoke coming from the oven vent.
• Trap bulk storage tanks with carbon canisters, and
maintain these canisters on a regular basis.
• Minimize or eliminate the use of volatile chemical
auxiliaries in aqueous processes.
1.2.1.4 Indoor Air Pollution Prevention Strategies
The following strategies can be used to reduce indoor
air pollution:
• Review all MSDS information to identify potential la-
tent emissions in manufactured textile products (14).
• Ensure that all reactive finishes are used under ap-
propriate curing conditions (e.g., time, temperature,
moisture) so that reactive volatile components (e.g.,
formaldehyde) are properly bound.
• Do not store volatile organic chemicals with textile
products near a warehouse because the textiles can
sorb and release the chemicals, causing indoor air
pollution (14).
• Control sorption of perchloroethylene (dry-cleaning
process solvent) by textiles stored near recently
cleaned clothing (20).
• Minimize or eliminate the use of chemical finishes.
Instead, substitute better fabric design and mechani-
cal finishing wherever possible.
7.2.2 Water Pollution
Textile manufacturing is one of the largest industrial
producers of wastewater (3). On average, approxi-
mately 160 pounds of water (20 gallons) are required to
produce 1 pound of textile product. Textiles also is a
chemically intensive industry, and therefore, the waste-
water from textile processing contains processing bath
residues from preparation, dyeing, finishing, slashing,
and other operations. These residues can cause dam-
age if not properly treated before discharge to the envi-
ronment (10).
'16
-------
1.2.2.1 Pollution Prevention Targets
Because textile operations produce so much wastewa-
ter, mills may be tempted to assume that they cannot
avoid large volumes of wastewater, and therefore, they
may become lax in pollution prevention. In practice, mills
vary considerably in the amount of waiter and wastewa-
ter pollutants they discharge. One essential and often
difficult step in water pollution prevention is to accurately
and realistically assess the mill's current status and its
potential for improvement. This assessment is neces-
sary to target specific waste streams that will maximize
pollution prevention.
The first step in a pollution prevention strategy for water
is a thorough audit and characterization of wastewater
from textile operations. Comparing the information from
this audit with benchmark data allows for realistic goal-
setting and economic projections for water pollution
reduction activities. Several options exist for bench-
marking an operation and, hence, for identifying pollu-
tion prevention targets.
Any wastewater stream deserves attention if (21-24):
• It exceeds industry norms.
• It exceeds publicly owned treatment works (POTW)
pretreatment or National Pollutant Discharge Elimi-
nation Standards (NPDES) permit limits.
• It is economically advantageous to eliminate.
• It is one of the four types most amenable to pollution
prevention (high volume, offensive, persistent or re-
sistant to treatment, dispersable).
This manual reviews many aspects of pollution preven-
tion that relate to wastewater, but se1:s aside some is-
sues for further discussion in other sections, including
water conservation, which is covered in Section 2.2.7.
1.2.2.2 Definition of Norms
Many studies have been published on water pollution
from textile operations. The most definitive, comprehen-
sive source of information is the Development Docu-
ment for Effluent Limitations Guidelines and Standards
for the Textile Mills published by the U.S. Environmental
Protection Agency (EPA) (25). This document assesses
the quantities and characteristics of wastewater pollut-
ants on a process-by-process and pollutant-by-pollutant
basis, using data based on current practices in the U.S.
textile industry. Tables 1-9 through 1-11 provide informa-
tion on:
• Water consumption and wastewater discharge (Table
1-9).
• Pollutants generated as a function of water con-
sumed (Table 1-10).
• Pollutants generated as a function of production out-
put (Table 1-11).
Using these tables, mills can estimate pollutant amounts
and concentrations in effluent for different types of textile
operations and for varying levels of water consumption
or production. With these benchmarking tables and an
accurate wastewater audit, mills can compare their
performance with industry norms, identify targets for
pollution prevention, and establish realistic pollution pre-
vention goals.
1.2.2.3 Comparison With Typical Permits
Certain pollutants in textile wastewater are more important
to target for pollution prevention than others. For example,
most dyeing machines have lint filters and other primary
control measures to keep lint out of heat exchangers and
off of the cloth; therefore, total suspended solids (TSS)
levels are low in raw textile dyeing wastewater compared
to many other industries (and compared to POTW pre-
treatment or NPDES discharge limits). On the other hand,
biological oxygen demand (BOD) and chemical oxygen
demand (COD) are relatively high in slashing, fabric for-
mation, and wet processing and, .therefore, are more im-
portant pollution prevention targets.
NPDES and POTW pretreatment permit limits can be
compared with textile wastewater when audited to iden-
tify further targets for pollution prevention. When com-
paring typical raw textile wastewater with typical
municipal sewer pretreatment requirements for indirect
dischargers, opportunities for pollution prevention can
be identified based on the limits shown in Table 1-12.
In addition to the pollutants shown in Table 1-12, the
following pollutants are prohibited through permit lan-
guage such as "no wastewater that imparts color," rather
than through specific numerical limits:
• Color
• Radioactivity
• Paint
• Explosives
• Flammable effluent
• Mud
• Straw
• Grit
• Fibers and feathers
• Noxious and malodorous effluent
• Cinders
• Grain
17
-------
Table 1-9. Water Consumption
Subcatogory
1. Wool scouring
2. Wool finishing
3. Low water use processing
4. Woven fabric finishing
a. Simple processing
b. Complex processing
c. Complex processing
plus desizing
5. Knit fabric finishing
a. Simple processing
b. Complex processing
c. Hosiery processing
6. Carpet finishing
7. Stock and yam finishing
8. Nonwoven finishing
9. Felted fabric finishing
Tablo 1-10. Median Raw Waste
Subcategory
and Wastewater Discharge Volumes by Subcategory (25)
Water Usage
Mln.
4.2
110.9
0.8
12.5
10.8
5.0
8.3
20.0
5.8
8.3
3.3
2.5
33.4
Med.
11.7
283.6
9.2
78.4
86.7
113.4
135.9
83.4
69.2
46.7
100.1
40.0
212.7
(L/kg)
Max.
77.6
657.2
140.1
275.2
276.9
507.9
392.8
377.8
289.4
162.6
557.1
82.6
930.7
Water Usage
(gal/lb production)
Min.
0.5
13.3
0.1
1.5
1.3
0.6
0.9
2.4
0.7
1.0
0.4
0.3
4.0
Concentrations by Subcategory (Based
BOD
(mg/L)
1. Wool scouring 2,270
2. Wool finishing
3. Low water use processing
4. Woven fabric finishing
a. Simple processing
b. Complex processing
c. Complex processing
plus desizing
5. Knit fabric finishing
a. Simple processing
b. Complex processing
c. Hosiery processing
6. Carpet finishing
7. Stock and yam finishing
8. Nonwoven finishing
9. Felted fabric finishing
170
293
270
350
420
210
270
320
440
180
180
200
COD
(mg/L)
7,030
590
692
900
1,060
1,240
870
790
1,370
1,190
680
2,360
550
COD/
BOD
3.1
3.5
2.4
3.3
3.0
3.0
4.1
2.9
4.5
2.7
3.77
13.1
2.75
TSS
(mg/L)
3,310
60
185
'
60
110
155
55
60
80
65
40
80
120
Med. Max.
1.4 9.3
34.1 78.9
1.1 16.8
9.4 33.1
10.4 33.2
13.6 60.9
16.3 47.2
10.0 45.2
8.3 34.8
5.6 19.5
12.0 66.9
4.8 9.9
25.5 111.8
on Effluent Volumes)
O&G" Phenol
(mg/L) (jig/L)
580 ID
IDb ID
ID ID
70 50
45 55
70 145
85 110
50 100
100 60
20 130
20 170
ID ID
30 580
Discharge
(median
m3/day
103
1,892
231
636
1,533
636
1,514
1,998
178
1,590
961
389
564
(25)
Chromium
(**g/L)
ID
ID
ID
40
110
1,100
80
80
80
30
100
ID
ID
mill)
MGD
0.051
0.500
0.061
0.168
0.405
0.168
0.400
0.528
0.047
0.420
0.254
0.100
0.149
Sulfide
(A*g/L)
ID
ID
ID
70
100
ID
55
150
560
180
200
ID
ID
Klft f\f
n\jf v\
Mills
12
15
13
48
39
50
71
35
57
37
116
11
11
Color
APHA
Units
ID
ID
ID
800
ID
ID
400
750
450
490
570
ID
ID
* O&G « oil and gas.
ID s insufficient data to report values.
18
-------
Table 1-11. Median Raw Waste Loads by Subcategory (Based on Production Volume) (11)
BOD COD
Subcategory (kgfekg) (kg/kkg)
1. Wool scouring 41.8 1,289
2. Woo! finishing 59.8 204.8
3. Low water use processing 2.3 14.5
4. Woven fabric finishing
a. Simple processing 22.6 ' 92.4
b. Complex processing 32.7 110.6
C; Complex processing plus desizing 45.1 122.6
5. Knit fabric finishing
a. Simple processing 27.7 81 .1
b. Complex processing 22.1 115.4
c. Hosiery processing 26.4 89.4
6. Carpet finishing 25.6 82.3
7. Stock and yarn finishing 20.7 62.7
8. Nonwoven finishing 6.7 38.4
9. Felted fabric finishing 70.2 186.0
a O&G = oil and gas.
ID - insufficent data to report values.
Table 1-12. Permitted Discharges (Survey of Six Cities, 1991
to 1994)
Item Limit (max. ppm)
Ammonia N 40
Arsenic 0.004-1 .0
Barium 1-100
Boron 1 .0
Cadmium 0.005-0.7
Chromium 0.03-1 .0
Copper 0.07-1 .0
Cyanide 0.03-2.0
Lead 0.03-0.6
Manganese 1 .0
Mercury 0.0002-0.1
Nickel 0.02-0.08
Nitrous oxide 10
Oil and grease 50-200
pH limit (low) 5-6
pH limit (high) 9-10
Phenol 10
Selenium 0.03-0.05
Silver 0.02-0.7
Solids 0.25-0.50 (inch)
Sulfide 5-10
Sulfur dioxide 10
Temperature 104-140 (°F)
Tin 1
Zinc 0.1-1.0
TSS O&Ga Phenol Chromium Sulfide
(kg/kkg) (kg/kkg) (g/kkg) (g/kkg) (g/kkg)
43.1 10.3 IDb ID ID
17.2 ID ID ID ID
1.6 ID ID ID ID
8.0 9.1 8.2 4.3 . 7.6
9.6 3.8 7.7 2.6 12.5
14.8 4.1 13.1 20.9 ID
6.3 4.0 8.7 7.8 13.0
6.9 3.5 12.0 4.7 14.0
6.7 6.6 4.2 6.4 23.8
4.7 1.1 11.3 3.4 9.4
4.6 1.6 15.0 12.0 27.8
2.2 ID ID 0.5 ID
64.1 11.2 247.4 ID ID
POTW pretreatment regulations control other parameters
, through surcharges. Surcharge systems provide economic
incentives for reducing, pollution. Examples of surcharges
for pollutant parameters are shown in Table 1-13.
1.2.2.4 Emerging Wastewater Issues
In general, wastewater treatment methodologies in the
textile industry are mature and well developed. The
industry and its regulators have focused on improving
the efficiency of existing treatment processes for some time.
The textile industry is concerned that some pollutants might
not be amenable to treatment with existing treatment
systems (19, 26). For these pollutants, prevention, not
treatment, must assume the primary role. These pollut-
ants include:
• Color residues in dyeing wastewater
• Electrolytes in dyeing wastewater
• Toxic air emissions from wastewater
• Low metals in dyeing wastewater
• Aquatic toxicity in dyeing wastewater
In addition to pollution prevention, water conservation
and treatability of wastes also need to be addressed for
these pollutants. These issues are covered in other
oar*+irvr»o rvf thio H/"\r»i im^nt
19
-------
Table 1-13. Examples of Economic Surcharges Applied to
Effluent Characteristics (1991 to 1994 Survey)
Item
Limit
Surcharge
Flow
BOD
COD
TSS
All
250-325
600
250-300
$0.123 - $0.35 per CCFa
$0.04 - $0.186 per excess pound
$0.122 per excess pound
$0.021 - $0.223 per excess pound
* CCF = hundred cubic feet.
1.2.2.5 Pollution Prevention Strategies
Appropriate pollution prevention strategies for wastewater
are discussed in various sections on pollution prevention
techniques and on individual unit processes. Although mak-
ing generalizations about pollution prevention is difficult,
most textile operations can develop and implement a
pollution prevention plan to reduce pollution from prob-
lem areas such as those shown in Table 1-14.
1.2.3 Solid Wastes
By volume, solid wastes are the second largest waste
stream in textile manufacturing, after effluent waste
streams. Textile processing produces many varieties of
solid waste, ranging from selvage trimmings to fly ash,
from aluminum cans to wooden pallets, and many others.
In the last few years, significant progress has been
made in preventing the generation of solid waste in
textile plants. The American Textile Manufacturers Insti-
tute (ATMI) has formed a Solid Waste Subcommittee
that champions pollution prevention initiatives.
Table 1-14. Priority Areas for Pollution Prevention in Textile
Operations
Production Area
Area To Address
Slashing and sizing
Preparation
BOD
COD
Water volume (from water-jet looms)
Dyeing
Printing
Finishing
BOD
COD
Temperature
pH
Metals
Aquatic toxicity
BOD
COD
TSS
Copper
pH
Temperature
Water volume
Air emissions
BOD
COD
TSS
Water volume
Air emissions
The quantities of solid waste generated depend greatly on
the size and type of textile operation, the nature of the
waste, the efficiency of the machinery or process generat-
ing the waste, and the level of awareness about solid waste
problems and management techniques among operators
and managers in the mill. According to a 1994 ATMI survey,
the largest quantities of waste generated (by tonnage) are
paper/trash, followed by wastewater sludge, cardboard,
and fly/bottom ash. Encouraging news from the survey
indicates that disposal methods for solid waste are
changing dramatically. Compared with a 1989 survey,
the percentage of solid waste sent to landfills fell from
70 to 33 percent, and the percentage of waste being
recycled rose from 23 to 65 percent.
Pollution prevention efforts tend to focus on reducing solid
waste through more efficient work practices; optimization
of waste-generating machinery and processes; and
reuse, recycle, salvage, and sale of solid waste. Exam-
ples of effective strategies include reusing containers,
purchasing chemicals in reusable containers rather than
bags, salvaging cardboard for sale to recyclers, and
training employees to sew seams straight, which results
in less off-cut waste.
1.2.3.1 Types of Solid Waste
Comprehensive studies have been conducted on solid
waste generation in textile operations (27). The main
types of wastes identified in these studies are listed in
Table 1-15. For the 290 facilities that participated in the
ATMI survey, the total amount of solid waste generated
was more than 51,000 tons per month. The disposition
of this waste was as follows (27):
• 32,675 tons, or 64 percent, was sent to public land-
fills.
• 11,984 tons, or 23 percent, was recycled.
• 3,119 tons, or 6 percent, was sent to private landfills.
• 467 tons, or 1 percent, was incinerated.
• 2,878 tons, or 6 percent, was disposed of by other
means (mainly wastewater treatment sludge dis-
posed of via land application).
1.2.3.2 Sources
Common types of solid waste and pollution prevention
strategies for the wastes are described below. Usually, the
sources of each waste type are obvious upon inspection.
A solid waste audit can identify waste sources that might
be overlooked in everyday operations. ATMI and other
organizations have developed survey forms to identify
sources of solid waste (27, 28). After identifying the
sources, mills can reduce or eliminate the associated
wastes if they remain committed to achieving their pol-
lution prevention goals.
20
-------
Table 1-15. Common Solid Waste Materials in Textile
Processing
Table 1-16. Packaging Wastes Used in Five TextHe Plants (7)
Material Amount
Aluminum cans
Ash
Bale wrapping
Cardboard
Card waste
Carpet backing
Carpet remnants
Carpet trim
Carpet waste
Compacted trash
Computer paper
Fabric waste
Fiber waste
Garbage
Glass
Hard plastic
Hard thread (sized)
Latex foam solids
Metal drums
Office paper
Paper bags
Paperboaid drums
Plastic bale wrap
Plastic containers
Plastic drum liners
Plastic drums
Plastic film
Rags
Scrap metal
Scrap wood
Selvage trimmings
Slasher waste
Soft thread
Surface finishing waste
Sweeps
Wastewater treatment sludges
Wooden pallets
Yarn waste
Ash and Sludge
Two major sources of pollution, boilers and wastewater
treatment, are directly related and are difficult to eliminate.
These sources generated approximately one-fourth of the
total, or more than 6,000 tons per month, in the 290
facilities surveyed by ATMI (27). Energy conservation pro-
grams can reduce boiler ash by decreasing the amount of
incineration required. Reductions in the chemical content
of wastewater and optimization of wastewater treatment
systems can decrease the level of sludge generated.
Packaging Materials
Another major source of solid waste is packaging mate-
rials. These materials include cardboard boxes, bale-
wrapping film or fabric, baling wire, wooden crates,
paper sacks, and drums made of paperboard, plastic, or
metal. In one operating division comprising five plants,
approximately 500 tons of packaging material waste
were generated in 1 year (7). Table 1-16 indicates the
types and amounts of packaging wastes that were gen-
erated. Reducing these wastes is leirgely a matter of
establishing and enforcing improved purchasing speci-
fications. All raw materials should be received in bulk or
returnable intermediate bulk containers (IBCs) if possi-
ble. Returnable IBCs or, bulk purchases of raw materials
eliminate waste and provide other benefits, such as:
• Reduced spillage
• Reduced handling costs
Bale wrap
Cardboard boxes
Metal drums
Paper bags
Paper drums
Plastic drums
Wooden pallets
Paper tubes and cones
100 tons
230 tons
3,250 count
41,500 count, or 10 tons
6,850 count
1,150 count
1,550 count
NAa
a NA = not available.
• Reduced packaging waste
• Reduced worker exposure to chemicals
• Simplified inventory
• Reduced cost of chemicals that are bought in bulk
• Savings in storage space (IBCs are stackable)
Drums
When purchasing chemicals in drums, returnable containers
should be specified, and the vendor should be required
to accept unwashed drums for return. Eliminating the
need to wash each drum before pickup can prevent a
significant amount of wastewater at the textile facility.
Bags
Many chemicals are purchased in bags (e.g., salt, triso-
dium phosphate [TSP], tetrasodium polyphosphate
[TSPP], soda ash, warp size). Bags often break, result-
ing in spillage, and disposing of them is a nuisance.
They cannot be stored near high traffic areas or wet
locations. They also must be moved on skids, which
frequently break, and handling bags requires a consid-
erable amount of labor. Wherever possible, mills should'
specify a preference for IBC packaging rather than bags
(all chemicals listed above are available in IBCs as well
as bags).
Paper Cones and Tubes
Yarns can be supplied on reusable plastic cones, and
cardboard yarn cases can be replaced with plastic
yarn pallets, which can be reused for many cycles.
Polyvinyl chloride (PVC) pipe is used as a durable
replacement for paper tubes in many,operations. In
addition to waste savings, rigid PVC tubes reduce
fabric distortion in knits.
Processing Wastes
Waste fabric, yarn, and fiber from processing accounts
for one-third of the total solid waste generated. In one
multifacility company (spinning, weaving, dyeing, and
21
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finishing), annual processing waste accounted for the
following:
• Fiber/Fabric/Yarn = 1,000 tons
• Sweeps = 150 tons
In many operations, selvage trimming and seam cutout
waste account for more than 2 percent of fabric produced.
Proper training, even for such apparently simple tasks
as sewing seams straight, can significantly reduce seam
waste as well as prevent creases and dye streaks at
seams. In a million-yard-per-week production facility,
this training could easily recover several thousand yards
per week of fabric waste.
Miscellaneous
Other solid wastes that textile facilities might generate
include scrap metal, trash, paper, and semisolid waste
oils, solvents, and sludges.
1.2.3.3 Pollution Prevention
Many industries have adopted the waste management
hierarchy established by the Pollution Prevention Act of
1990 as the basis for their waste management plans.
The Act emphasizes prevention of pollution at the
source and identifies recycling as well as treatment and
disposal as less desirable options. Using this approach,
companies seek to reduce the generation of wastes
wherever possible. Where source reduction of a waste
is not feasible, opportunities for recycling should be ex-
plored. For wastes that cannot be reduced or recycled,
treatment and disposal should take place in an environ-
mentally sound manner.
Source Reduction
Generally, reducing the generation of solid waste is the
most efficient method of pollution prevention. Waste re-
duction best proceeds from an auditing or waste mapping
procedure that can identify inefficiencies in the opera-
tion. Options for dealing with these inefficiencies are
investigated to identify the most promising options.
Source reduction schemes should be examined care-
fully for their impact on costs and their potential to
reduce salvage value or generate more pollution (or
work) than a recycling or reuse effort.
Reuse
If reducing solid waste is not possible, reuse of materials
is usually the next preferable waste management op-
tion. Uniformity of materials aids reuse options, as does
waste separation. For example, drums are easier to
handle, stack, and return if they are of only one type and
size. Fiber wastes from one machine are easier to reuse
if they are kept separate from other types of wastes.
Recycling
Recycling material can be considered the third-most
efficient waste treatment option. Recycling differs from
reuse in that energy may be required to convert the
waste into a usable form. The energy use occurs at the
recycling facility, rather than the textile mill (unless the
mill does its own recycling). Recyclable materials should
be specified in the production process wherever possible
to replace nonrecyclable materials. For example, a mill
might specify burlap bale wraps or Tyvek bale covers,
rather than polypropylene, which is not easily recyclable.
Disposal
Efficient disposal options are those that make good use
of the waste during disposal and that minimize environ-
mental impacts. Examples include incineration of old
and broken pallets to recover their fuel value. Note that
to be efficient, incineration should be performed using
environmentally safe techniques. The least efficient form
of solid waste treatment involves dumping or landfilling,
serving no purpose other than waste disposal. This, of
course, has traditionally been the only solid waste dis-
posal method used by most industries.
1.2.3.4 Types of Waste Management Practices
Auditing Solid Waste
The generation, location, and physical nature of the solid
waste must be investigated, documented, and analyzed
before developing a waste management plan. Auditing
or waste mapping procedures are well documented in
various reports, especially in A Guide To Pollution Pre-
vention in Woolen Mills (29). Waste auditing can pro-
ceed by one of two general methods. Process flow
mapping is a methodology that generates its information
from direct observation and brainstorming of operational
procedures. The second method of waste auditing in-
volves touring the facility with worksheets or checklists
of waste possibilities to aid the auditor in finding waste
streams. The ATMI solid waste surveys presented fairly
comprehensive forms on which to list solid waste streams .
(27). One limitation of this type of checklist is that it
prespecifies the waste streams, which increases the
possibility that important streams in a particular opera-
tion might be left out. The audit procedure should en-
courage the textile facility to think of other possible solid
waste sources without constraint.
Cost Factors
Assigning cost factors to each kind of waste can be
useful in evaluating the impact that changes in these
waste streams could have on plants or departments.
Cost factors can also be used to foster appropriate
pollution prevention incentives at the facility. For exam-
ple, fiber sweeps have almost no value and are to some
22
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extent preventable by orderly work practices. In the
waste analysis, these should count heavily against a mill
or operational group. Clean, reprocessable fiber waste,
on the other hand, has a high reuse value and should
not be weighted so high. Another example is pallets,
which, if handled carefully, are reusable for a long time.
Broken pallets should count fairly heavily against the
mill on its "waste score." The following are important
basis points in determining incentive or worker reward
programs:
• Cost of disposal.
• Value of salvage.
• Loss of value from next best salvageable form (e.g.,
value difference between a broken pallet and an in-
tact pallet).
• Influence a worker has on the waste (e.g., ash is not
preventable and should not count much, whereas
broken pallets are preventable and should count more).
Example of cost factors to consider are shown in
Table 1-17.
A system such as this is appropriate for comparing
similar operations, such as greige mills. This makes
workers more aware of the amount of waste and their
performance, and keeps waste in its in highest value form.
Salvage Value
Some companies "advertise" or otherwise offer potentially
reusable materials to others to improve the efficiency of
waste reuse and recycle. Advertising is conducted in
waste exchange newsletters, through telephone hotli-
nes, or on computer bulletin board systems (BBSs).
1.2.3.5 Pollution Prevention for Specific
Categories of Solid Wastes
Paper and Cardboard
Common wastes such as paper, cardboard, and empty
paper drums must be baled, crushed, or shredded be-
fore disposal or recycling. One central waste processing
center may be able to handle this waste better and more
Table 1-17. Cost Factors in Textile Wastes
Type of Waste
Pallets
Broken pallets
Empty size bags
Waste fiber
Sweeps
Disposal/Salvage
Value per Unit
(e.g., ton, count)
$2 gain
$6 loss
$6 loss
$2 gain
$6 loss
Next Best
Form of Waste
None
Pallet
None
Reworkable
waste
Fiber waste
Worker
Influence
None
li/luch
None
Moderate
Great
economically than individual mills because of the cost of
the equipment, such as shredders and balers. The dis-
advantage of this arrangement is the cost and logistics
of transportation to the central location. The feasibility,
however, of establishing a central waste processing
center for outside recyclers should be considered.
Suppliers buy back used paper tubes and cones. Intact
tubes can be reused directly, and damaged tubes can
also be reused by salvaging shorter pieces from longer
damaged tubes (e.g., a 60-inch tube with a damaged
end can be cut off and used at standard 48-inch length).
Fibers and Fabric
Fibers, sweeps, rags, yarn, and cloth scraps have salvage
value and should generally be collected and sold wher-
ever possible. This is standard practice in most mills,
and many buyers are available for these high-value
wastes.
Reworkable fiber waste of 5 percent is typical in spinning
operations and can be completely reclaimed by intro-
ducing it back into the opening line through a waste
hopper. Fabric trimming can be difficult to compact and
thus produces a very low-density waste that takes up a
substantial amount of space in landfills.
Pallets
Pallet use should be minimized by buying as many
large-volume chemicals as possible in IBCs or bulk or
returnable containers, especially bagged chemicals
such as warp size. Scrap pallets can be recycled or used
in two ways, either as pallets or as fuel. Many pallet
recycling operations recover materials and energy from
broken pallets in an environmentally safe manner.
Not all pallets are recyclable, but using recyclable pal-
lets despite higher initial cost is economical in the long
term. Important factors in pallet recycling are listed below:
• Weight.
• Exact stringer length and size.
• Number of deck boards (top and bottom).
• Dimensions and length of deck boards.
• Whether they are two-way or four-way (accessible
from two or four sides).
Pallets that cannot be sold can be chipped and burned
in boilers, but this process generally requires removal of
nails, staples, and other metal before chipping. Pallet
chippers are readily available. A drum shredder, if avail-
able, can be used for shredding pallets, but the cost of
such equipment is high compared with a pallet chipper.
Drum shredders cost up to $80,000 and have a capacity
of up to 500 units (e.g., pallets, drums) per day.
23
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Drums
Other Wastes
Metal drums, like pallets, can be recycled or shredded
and sold as scrap metal. Several drum recyclers will
pick up part loads as small as 50 drums. Other options
for drums include returning them to the supplier and
internal reuse. Purchasing contracts for chemicals
should specify returnable drums or other containers,
such as gas cylinders. Procedures for establishing such
specifications are part of a facilitywide prescreening
protocol described in Chapter 3.
One problem that can aggravate attempts to recycle
drums is the sheer variety of drum sizes. This creates
problems in handling, storage, and reuse. The main
plastic and metal drum sizes are listed in Table 1-18.
Bags
Bags (empty chemical sacks), paper, and cardboard can
be baled and resold for about $12 per ton. Most recy-
clers require that paper be bailed, an investment of
about $6,000. Cardboard yarn cases can be reused
several times, and many companies have policies re-
quiring such material to be recovered and reused. An
alternative to yam cases is plastic yarn pallets, which
are shrink-wrapped to pack the yarn for shipment.
By purchasing chemicals in bulk or in IBCs, the textile
facility can not only reduce chemical costs but also
reduce or eliminate problems such as waste paper
sacks and pallets. Other advantages include reduced
costs for storage, handling, labor/lifting, employee expo-
sure, spillage (broken bags), inventory, and warehouse
space. Chemicals often purchased in bags include:
• Common salt
• Glaubers salt
• Warp sizes
• Soda ash
• TSP
• TSPP
Table 1-18. Drum Sizes for Textile Chemicals
Chomlcal
Sodium bromate (oxidlzer)
Processing assistants
Dyes
Dyes
Dyes
Miscellaneous (e.g., shop solvents)
Height
(inches)
18
38
31
27
35
27 or 37
Diameter
(inches)
17
22
22
22
22
22
Burlap bale wrap can be sold with rags and other fiber
waste through a waste exchange or to a recycler. Most
bale covers, however, are either polypropylene orTyvek.
Although Tyvek covers can be sold or reused, the
polypropylene is not reusable and should be avoided.
Bale straps and bailing wire can be sold to scrap metal
dealers only if they are cut into short pieces.
Summary
To avoid generating these wastes, mills should empha-
size the following actions:
• Buy chemicals (e.g., size, salt) in bulk or IBCs to
reduce the number of bags and pallets acquired.
• Recycle bags.
• Sell used pallets to a recycler.
• Donate damaged pallets to employees or institutions
(high school shop) for the wood.
• Chip, then burn pallets in boilers.
7.2.4 Hazardous Waste
Most textile operations produce little or no hazardous
waste as part of their routine operations, but a small
percentage of textile mills (perhaps 10 percent to 20
percent) are hazardous waste generators. Any facility
that uses chemicals can produce hazardous waste if a
chemical exhibiting the hazardous characteristics of ig-
nitability, toxicity, corrosivity, reactivity, or flammability is
spilled on the ground. The contaminated soil from such
a spill is often hazardous waste by the legal definition
and must be handled accordingly.
Generators must prepare both for routine handling of
hazardous waste and for emergencies through proper
training, equipment, and policies. For facilities that gen-
erate and handle hazardous waste, hazardous waste
policies are essential. Policies must be realistic and
must actually encourage proper practices. Policies de-
signed mainly to protect the employer from liability and
that do not actually promote safety and pollution preven-
tion should be avoided.
1.2.4.1 Waste Generation and Storage
Treatment and disposal of hazardous waste is expen-
sive and difficult, and the associated liability is great.
The key to minimizing cost and risk exposure is to
minimize these wastes to the maximum extent possible.
Thus, the economic incentive to eliminate these wastes
through pollution prevention practices is great. Many
textile mills have completely screened out materials that
produce hazardous waste, and continue to do so, to
avoid producing expensive hazardous wastes.
24
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Facilities that produce or treat, store, and dispose (TSD)
of hazardous waste must obey very specific regulations.
Any hazardous waste generator must be fully aware of
these regulations and must comply with them (e.g., by
obtaining proper permits, keeping proper records). Any
facility that stores hazardous waste more than 30 days
is by legal definition a storage facility.
Generators are classified according to the amount of
hazardous waste they produce. Large generators pro-
duce more than 1,000 kilograms per month of such
waste, and small generators produce 100 to 1,000 kilo-
grams per month. Each mill must determine its hazard-
ous waste status and must understand and abide by the
appropriate regulations.
1.2.4.2 Waste Disposal
Under national hazardous waste laws, (generators of haz-
ardous waste have the ultimate responsibility for safe
removal and disposal of all hazardous waste they produce.
A textile mill's liability cannot be assigned or transferred to
a contractor who removes or disposes of the waste. There-
fore, one of the most important issues for the hazardous
waste generator is to monitor TSD contractor activities.
The generator should contact local, state, and federal
authorities to check the credentials of TSDs contractors.
If a TSD contractor fails to handle hazardous waste
properly, both the transporter and the generator(s) who
produced the waste are jointly liable for damages. Thus,
the generator must make every effort to ensure that the
transporter is perfectly reliable, properly trained, and
highly prepared. A common practice is for a generator
to accompany the transporter to verify the proper ulti-
mate destruction or disposal of wastes.
1.2.4.3 Hazardous Waste Sources in Textile
Operations
Several textile processes can potentially generate haz-
ardous waste as a normal, routine by-product. In addi-
tion, occurrences such as spills, process excursions,
and upsets can produce hazardous waste unexpectedly.
Although many textile mills screen out chemicals that
might potentially generate hazardous waste, abnormal
events that result in hazardous waste spills can still
occur and must be planned for.
Common sources of spills and upsets in textile opera-
tions include:
• Dry cleaning
• Solvent scouring
• Solvent-based coating operations
• Shop activities
Spills
Bulk off-loading and storage areas are susceptible to spills.
Discharge of a reportable spill quantity of hazardous
material beyond a preplanned containment constitutes
a hazardous spill and the associated problem of hazard-
ous waste disposal. The key concept is "preplanned." To
avoid producing hazardous waste from spills, facilities
must develop advance planning programs, including:
• Employee training on spill response.
• Policies regarding off-loading practices and activities.
• Preplanned containments.
• Facility design to ensure ease of spill cleanup.
• Absorbent materials on hand.
• Prescreening to avoid having hazardous materials
on site.
• Auditing and preventive maintenance on a regular
schedule.
Dry Cleaning
Some mills use chlorinated solvents for batch dry clean-
ing as well as spot removal in the final inspection de-
partment. These materials are efficient in removing
oil-based stains from cloth and sewn products, but they
have the potential to become a hazardous waste, even
if recycled on site through distillation processes. In that
case, the still bottoms must be disposed of as hazardous
waste. „
Facilities can avoid hazardous wastes from these proc-
esses in several site-specific ways. The most effective
way is to address the source of the oil contamination.
Often, the source is lubricating oils that drip or sling from
moving or rotating machine parts (e.g., oven stacks
and dampers, tenter frame drive chains, sewing ma-
chines, knitting oils). Because the main function of the
dry-cleaning or spot-removal operation is repair work,
improvements in preventive maintenance, better em-
ployee training in the use of lubricants, or selection of
better lubricants can reduce or eliminate the need for
extensive repair work.
>
Solvent-Coating Operations
Coating operations based on latex materials and solvents
such as methyl ethyl ketone (MEK), methyl isobutyl
ketone (MIK), acetone, toluene, and xylene are some
of the largest sources of hazardous waste in the textile
industry. These fabrics are used in waterproof prod-
ucts, offset printing blankets, landfill liners, and other
engineered textile products. They often are produced by
swelling or dissolving natural or synthetic rubber or latex
materials in a mixture of solvents, as noted above. These
solutions or plasticized materials are then spread or
sprayed onto the fabrics, which are then dried or cured.
25
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The residual portions of these solutions must be han-
dled as hazardous wastes. As in printing or finishing,
a key preventive measure is to ensure that only the
exact amount of coating material necessary for the
run is prepared. Mills that produce such products
often do not follow this practice, however, because
such products are high value-added items. These
mills may view waste control as a secondary issue
because economic incentives associated with waste
prevention are weaker than those associated with
commodity-type operations.
Mills should also explore the possibility of using water-
based emulsions for fabric coatings. In many applica-
tions (thougn not all), this is a technically feasible
substitution. Also, newer forms of materials (e.g., fiber-
reinforced composites) may be a reasonable replace-
ment for coated fabrics in certain applications. Where
aqueous substitutes are not suitable, alternative product
design should be considered for the specific end-use.
Shop Chemicals
Many shop chemicals are hazardous and become haz-
ardous waste once they are used or become obsolete.
These chemicals include insecticides, cooling tower
treatment chemicals, weed killers, biocides, machine
cleaners, paint strippers, and floor finishes. These classes
of chemicals often are not evaluated with the same care
as production chemicals. Every chemical in the mill,
including shop chemicals, warrants the same level of
hazardous waste screening.
1.2.4.4 Hazardous Waste Recordkeeping and
Handling
Once hazardous waste is produced, maintaining proper
documentation and proper waste handling procedures
is essential. All hazardous wastes should be segregated
from other wastes and raw materials to avoid increasing
the amount of hazardous waste by mixing hazardous
and nonhazardous wastes. Proper storage facilities are
necessary to avoid leaks, seepage, or other release of
the waste prior to pickup and disposal by a permitted
TSD contractor. Records and manifests are required
and should be available for review at any time.
Any chemicaHhat potentially could become or contrib-
ute to a hazardous waste should be subjected to special
audits and recordkeeping. Some of the important infor-
mation to record about the hazardous waste includes:
• Amount
• Characteristics
• Disposal practices
• Annual reports submitted
• Permits (generator and TSD)
Generators must obtain permits not only to produce the
waste but also to store it if the waste is held on site for
more than 30 days. A storer who is not a generator (e.g.,
a trucking company depot) must obtain a permit no
matter how briefly waste is held on site.
Shipping records must be carefully kept, and the shipper
must maintain careful security of the waste, as well as
a paper trail that leads clearly back to the generator.
Appropriate training is required for truck drivers and
other personnel involved in transport, storage, and dis-
posal. Drivers must deliver wastes only to a permitted
facility. All transportation vehicles must carry emergency
equipment on board, and any losses or spills of hazard-
ous waste must be reported immediately.
1.2.4.5 Prevention Strategies
The most powerful pollution prevention strategy for haz-
ardous waste, and the most widely used in textiles, is
total avoidance of pollution by prescreening chemicals.
Dividing textile chemicals into two groups, commodities
and specialties, facilities can establish methods to pre-
screen and check raw materials as they arrive to avoid
many hazardous waste problems. These procedures
are explained in detail in Sections 4.4, "Chemical Spe-
cialties," and 4.5, "Chemical Commodities," but they are
mentioned here specifically in relation to pollution pre-
vention for hazardous waste.
One main reason for prescreening chemicals is to avoid
introducing into the plant materials that will become or
contribute to hazardous waste. Prescreening informa-
tion must by law be specifically noted on the MSDS,
along with appropriate spill control information.
Commodities are usually bought by the truck (or railway
car), stored in bulk tank farms, and used in massive
quantities. Many of these materials are corrosive or
highly reactive. They are often handled with automated
bulk chemical handling to reduce cost and potential for
routine wastes. Bulk handling, however, increases the
potential for large-scale spills from tank trucks and bulk
handling systems, as well as associated production of
hazardous waste.
Important pollution prevention considerations with these
commodity chemicals are:
• Proper receiving, storage, and handling procedures.
• Routine, incoming raw material testing for impurities
(e.g., metals) that might produce hazardous process
wastes or treatment sludges.
• A strong program of preventive maintenance for bulk
handling facilities.
• Thorough training of employees who use automated
bulk chemical handling systems.
• Proper training on large-scale spill response.
26
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Specialties, on the other hand, are generally complex
mixtures of unknown composition to the user (and often to
the vendor as well) and cannot be handled the same way
as commodities. Testing and prescreening of specialties
must follow a less specific and more generic protocol,
as presented in Section 4.4, "Chemical Specialties."
Careful review of all MSDS information is.even more
important with specialties because many seemingly
harmless specialty chemicals can cointain relatively in-
sidious and hazardous ingredients.
To avoid the production of hazardous waste, textile mills
should look for any component that:
• Is a listed hazardous air pollutant (HAP) or toxic air
pollutant (TAP).
• Is a listed priority pollutant.
• Exhibits high aquatic toxicity.
• Contains hazardous or toxic metals.
• Tends to accumulate in facility or in treatment sludges.
• Will react with other chemicals on site to produce
hazardous waste.
• Will be a hazardous waste if spilled on the ground.
• Is not suitable because the plant is not equipped to
handle it in terms of:
- Worker expertise, training
— Engineering controls and storage facilities
- Personal protective equipment
The plant should request all necessary information from
the vendor before even starting to evaluate the chemical
in production. If the vendor cannot or will not help in such
an evaluation, the plant should identify and contact al-
ternate vendors.
Once adopted, raw material testing of all incoming ship-
ments should be conducted according to the protocols
described in Sections 4.4, "Chemical Specialties," and
4.5, "Chemical Commodities."
1.2.4.6 Process Review
In reviewing processes, mills should ask the following
types of questions:
• What is mixed together?
• What reaction might occur under normal conditions?
• What reaction might occur under exceptional condi-
tions?
• Is the level of expertise of the operator sufficient?
• Is the process machinery adequate?
• Is the process control system adequate?
If a hazardous waste is produced, the mills should then
ask:
• Where does waste originate from in the process?
• Can the hazardous waste be reused or recycled on site?
• What are the alternative processes?
1.3 Summary
This chapter presented a brief overview of textile proc-
esses, the wastes that these processes generate, and the
major pollution prevention approaches that are applicable
to each process or waste stream. The chapter highlighted
the enormous diversity of operations found within textile
facilities. Although each process has its own unique
wastes and environmental concerns, the chapter also
identified numerous issues that are common to a variety
of textile processes and corresponding pollution preven-
tion approaches that can be applied to these problems.
The remaining chapters in this manual explore textile
operations in greater detail. They identify both general
and specific pollution prevention approaches to prob-
lems encountered in textile facilities:
• Chapter 2 first provides a method for categorizing
wastes and identifies, pollution prevention approaches
applicable to each waste type. The chapter then
takes a detailed look at some of the most important
pollution problems in textile operations, such as color,
salt, air emissions, wastewater treatability, metals,
aquatic toxicity, and water conservation. In addition
to providing data on the sources and extent of these
problems in the industry today, the chapter identifies
the main pollution prevention strategies available for
addressing each problem.
• Chapter 3 describes general pollution prevention ap-
proaches that are not specific to individual processes
but may apply throughout the textiles operation. It
covers issues such as designing processes and prod-
ucts to incorporate pollution prevention, developing
expertise for evaluating chemical use, operating and
maintaining equipment to minimize pollution, operat-
ing equipment to reduce water consumption, and
reusing and marketing process wastes.
• Chapter 4 is a process-by-process examination of
textile operations that takes the reader through the
life cycle of textile products, from raw fiber production
and handling through yarn manufacturing, fabric for-
mation, fabric preparation and finishing, and cutting,
sewing, and fabrication. Each chapter describes the
process, equipment, and chemicals that are used,
identifies the pollutants that the process generates
and their sources, and discusses pollution preven-
tion opportunities available for reducing or eliminat-
ing wastes. The chapter highlights the need for a
27
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global approach to pollution prevention because
many pollution problems faced by textile facilities are
the result of processes used at upstream production
facilities or design, product, or finishing decisions
made elsewhere.
• Chapter 5 provides an overview of the major steps
involved in setting up and implementing a pollution
prevention program. It describes the building blocks
for an effective pollution prevention effort, such as
management commitment, employee involvement,
project evaluation skills, and communication about
program results. It also details some of the major
pollution prevention tools, such as waste audits, and
how they can be applied in textile operations.
• Chapter 6 discusses the need to provide appropriate
incentives to encourage and facilitate adoption of the
pollution prevention approach. It identifies barriers
that sometimes limit facilities' ability to implement pol-
lution prevention and offers suggestions for breaking
down these barriers.
• Chapter 7 provides abstracts of selected case stud-
ies of pollution prevention initiatives taken at textile
facilities in the United States and elsewhere. Wher-
ever possible, these case studies identify the costs
of each initiative and the benefits obtained. Hope-
fully, these case studies will provide inspiration to
companies as they undertake their own pollution
prevention initiatives.
1.4 References
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United States. U.S. Government Printing Office, Washington, DC.
2. Freedonia Group. 1992. Textile fibers. The Freedonia Group,
Cleveland, OH (June).
3. Smith, B. 1989. ATI's dyeing and printing guide. Amer. Textiles
Int. (ATI) (February).
4. Office of Management and Budget. 1987. Standard industrial
classification manual. National Technical Information Service,
Springfield, VA.
5. Bureau of the Census. 1992. County business patterns 1989 and
1990 (CD/ROM). U.S. Government Printing Office, Washing-
ton, DC.
6. Mohr, U. 1993. Ecology must be dealt with. Australasian Textiles
(January/February), p. 45.
7. Smith, B. 1989. Source reduction by new equipment. Presented
at Pollution Resource Reduction in Textile Wet Processing,
Raleigh, NC (May 23-24).
8. Goodman, G.A., J.J. Porter, and C.H. Davis, Jr. 1980. Volatile
organic compound source testing and emission control. Clemson
University Review of Industrial Management and Textile Science
(January).
9. Zeller, M.V. 1975. Instrumental techniques for analyzing air pol-
lutants generated in textile processing. Textile Horizons (January).
10. Smith, B. 1986. Identification and reduction of pollution sources
in textile wet processing. North Carolina Department of Natural
Resources and Community Development, Pollution Prevention
Pays Program, Raleigh, NC.
11. U.S. EPA. 1988. Estimating chemical releases from textile dyeing.
EPA/560/4-88/004h. Washington, DC (February).
12. Castle, M. 1992. A novel approach to practical problems. J. Soc.
, of Dyers and Colourists (July/August), p. 306.
13. McCune, E.G. 1994. Facility total emissions summary: Annual air
pollutant emissions inventory for 1993. State of North Carolina,
Department of Environment, Health, and Natural Resources, Di-
vision of Environmental Management, Raleigh, NC.
14. Smith, B., and V. Bristow. 1994. Indoor air quality and textiles:
An emerging issue. Amer. Dyestuff Reporter (January), p. 37.
15. Mock, G.N. 1984. Fundamentals of dyeing and printing. North
Carolina State University, Raleigh, NC.
16. Kulube, H.M. 1987. Residual carrier components in exhausted
textile dyebaths. Master's thesis, Department of Textile Chemis-
try, North Carolina State University, Raleigh, NC.
17. Leovic, K.W., J.B. White, and C. Sarsony. 1993. EPA's indoor air
pollution prevention workshop. Presented at the 861h Annual Air
& Waste Management Association Meeting, Denver, CO (June).
18. Bayer, C. 1992. Indoor environment testing using dynamic envi-
ronmental chambers. ITEA Journal (December).
19. Smith, B. 1994. Future pollution prevention opportunities and
needs in the textile industry. In: Pojasek, B., ed. Pollution pre-
vention needs and opportunities. Center for Hazardous Materials
Research (May).
20. Brodmann, G. 1975. Retention of chlorinated solvents in fabrics.
Textile Chem. and Colorist.
21. Smith, B. 1989. Pollutant source reduction: Part 1—An overview.
Amer. Dyestuff Reporter (March), p. 28.
22. Smith, B. 1989. Pollutant source reduction: Part 2—Chemical
handling. Amer. Dyestuff Reporter (April), p. 26.
23. Smith, B. 1989. Pollutant source reduction: Part 3—Process al-
ternatives. Amer. Dyestuff Reporter (May), p. 32.
24. Smith, B. 1989. Pollution source reduction in textile wet process-
ing. North Carolina Department of Natural Resources, Pollution
Prevention Pays Program, Raleigh, NC (May).
25. U.S. EPA. 1979. Development document for effluent limitations
guidelines and standards for the textile mills: Point source cate-
gory (proposed). EPA/440/1-79/0226. Washington, DC (October).
26. Wagner, S. 1993. Improvements in products and processing to
diminish environmental impact. COTTECH Conference, Raleigh,
NC (November 11-12).
27. Lejeune, T.H. 1993. Future issues in solid waste management.
In: Proceedings of the Conference for Executives and Managers
on Environmental Issues Affecting the Textile Industry, Charlotte,
NC (June 14-15). North Carolina Department of Environment,
Health and Natural Resources, Raleigh, NC.
28
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2S. Tuggte, A.. 1993. SoVid waste management in the textile plant.
Solid waste management in the textile plant. In: Proceedings of
the Conference for Executives and Managers on Environmental
Issues Affecting the Textile Industry, Charlotte, NC (June 14-15).
North Carolina Department of Environment, Health and Natural
Resources, Raleigh, NC.
29. Calfa, L., J. Holbrook, C. Keenan, and T. Reilly. 1993. A guide to
pollution prevention in woolen mills (Capstone Project). Prepared
for Northern Textile Association (July).
29
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Chapter 2
Waste Categorization/Prioritization for the Textile Industry
This chapter describes a general categorization scheme
for wastes generated in the textile industry (Section 2.1)
and numerous specific wastes or pollution issues that
are considered priorities for the industry (Section 2.2).
Section 2.1, "General Waste Categorization," provides
a framework for thinking about different types of waste
generated in textile operations and the general ap-
proaches applicable to each type. Section 2.2, "Specific
Wastes or Waste Problems," addresses many specific
waste types or waste problems for textile operations.
These wastes may be produced in one or more textile
process areas and thus may be cross-referenced to one
or more sections in Chapter 4, "Pollution Prevention in
Specific Textile Processes."
2.1 General Waste Categorization
This section describes four general categories of textile
waste that are particularly suitable for reduction through
pollution prevention measures such as material substi-
tution, process modification, inventory control, better
management techniques, recovery, reuse, and recy-
cling. Each type of waste has specific characteristics
that require different pollution prevention approaches.
The four categories of wastes are:
• Dispersible wastes
• Hard-to-treat wastes
• High-volume wastes
• Hazardous and toxic wastes
2.1.1 Dispersible Wastes
Many wastes that are well contained when generated
become highly dispersed once they are released or
mixed with other wastes. It is important to segregate and
capture such highly dispersible wastes at the source
because removing them from a mixed waste stream
requires substantially more treatment at greater cost
and effort. Examples of these wastes in the textile indus-
try include:
• Waste streams from continuous operations (e.g., fin-
ishing, dyeing, printing, preparation).
• Print paste (especially from screen, squeegee, and
drum cleaning).
• Lint.
• Waste from coating operations (especially foam).
• Waste solvents from machine cleaning.
• Still bottoms from solvent recovery (especially dry-
cleaning operations).
• Batch dumps of unused processing (especially finish-
ing) mixes.
In each of these cases, facilities are generally able to
capture the waste in its concentrated form for more
efficient, cost-effective treatment. These wastes are
often allowed to mix with other wastes, however, com-
plicating collection, disposal, salvage, or recycle/reuse.
Even if the waste does not have reuse or recycle poten-
tial, it can usually be collected and prepared for disposal
much more easily if it is not diluted or contaminated.
Sources of dispersible wastes are widespread in textile
wet processing:
• Pastes: Pastes generally come from printing and in-
clude oil/water pastes and acrylic polymers. Both
types tend to gel and form lumps in drains. These
wastes can be difficult to sample with automated
equipment because of their tendency to stop up sam-
pler lines, pumps, and filters.
• Lint: Lint can originate from many textile operations,
particularly preparation, dyeing, and washing opera-
tions. Usually, removing lint is fairly easy using pri-
mary control measures such as filters, which can be
placed in the circulation lines of dyeing machines and
other equipment. The filters must be maintained and
cleaned out on a regular basis to ensure proper op-
eration. The collected lint usually can be dried and
then landfilled or incinerated. Higher quality lint can
be marketed.
• Solvent: Proper handling of solvents can make dis-
posal much easier; once mixed with water, however,
solvents become difficult to manage. Also, solvent
reclamation and reuse is much easier before solvents
are mixed with other wastes. Some tips and tech-
31
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niques for proper handling are described in Sections
2.2.3, 'Toxic Air Emissions," and 3.8, "Maintenance,
Cleaning, and Nonprocess Chemical Control." In gen-
eral, the key is to avoid dumping solvents down the
drain with other wastes.
• Wastes from continuous processes: Dumps of dye
and chemical mixes sometimes occur in continuous
textile operations such as slashing, preparation, con-
tinuous dyeing, printing, coating, and finishing. Pollu-
tion prevention techniques that can be used include
equipment modification, maintenance procedures,
housekeeping, waste capture, and segregation of con-
centrated wastes from the general waste streams.
2.1.2 Hard-To-Treat Wastes
Hard-to-treat wastes include those that are persistent,
resist treatment, or interfere with the operation of waste
treatment facilities. They often contain nonbiodegrad-
able or inorganic materials. Biological processes that
occur in waste treatment systems generally cannot re-
move or break down these wastes.
Hard-to-treat textile wastes include color, metals, phe-
nols, certain surfactants, toxic organic compounds, pes-
ticides, and phosphates. Color and metals originate
primarily from dyeing or printing operations, although
metals are sometimes found in other processes (see
Section 2.2.5, "Metals"). Phosphates are used primarily
in preparation and dyeing (see Section 3.5, "Chemical
Alternatives"). Nonbiodegradable organic materials in-
clude certain surfactants (see Section 4.4, "Chemical
Specialties") and solvents (see Section 2.2.3, Toxic Air
Emissions"). These materials can resist treatment, pass
through standard activated sludge systems, and contrib-
ute to aquatic or air toxicity.
Another example of a hard-to-treat waste is pesticide
residue that is present in wool-processing wastewater.
Mickeison et al. (1) report that several different chemical
pesticides are used to process wool. The degradability
of each is given in Table 2-1. Information such as this,
in combination with other relevant data (e.g., aquatic
toxicity of the materials, their degradation products, the
amount of material released during production), should
be used as a guide in selecting the appropriate pesticide
(1). For more information,,see Section 4.12, "Finishing."
Achwal (2) reported that preservatives such as biocide
additives in warp size materials can interfere with waste
treatment system operation and can, in some cases,
inhibit aerobic stabilization of wastewater. Some coun-
tries have banned the use of chlorinated phenols as a
size additive. Undegraded size materials can cause
biomass to aggregate (flock) and inhibit oxygen transfer.
Starch can cause the growth of hard-to-settle filamen-
tous bacteria, interfering with the operation of clarifiers.
Synthetic sizes, mainly polyvinyl alcohol (PVA), do not
Table 2-1. Degradability of Alternative Pesticides in
Wastewater Treatment Systems (1)
Pesticide
Percent Degraded
Dieldrin
Dichlorofenthion
Diazinon
Cyperethrin-1
Cyperethrin-2
Deltamethrin
81
79
87
84
90
92
cause these problems, nor are they toxic. Residues from
other synthetic sizes, however (such as polyacrylic acid
[PAA]), are also hard to treat and require tertiary treat-
ment. For more information, see Section 4.7, "Slashing
and Sizing."
Because of the difficulties involved in treating some of
these wastes, efforts should be made to identify and
eliminate their sources wherever possible. Several
methods of prevention are particularly effective, includ-
ing chemical or process substitution; improved process
control and optimization; waste segregation, capture,
and reuse/recycle; and improved employee work prac-
tices. Each method is discussed briefly below.
2.1.2.1 Chemical or Process Substitution
Several strategies are appropriate for eliminating of-
fending and hard-to-treat chemicals from a process,
including:
• Substituting other, easier-to-treat chemicals: Exam-
ple: Substituting linear alkylbenzene sulfonates for
hard-to-treat alkylphenol (AP) in scouring eliminates
waste system pass-through and aquatic toxicity (see
Section 4.4, "Chemical Specialties").
• Making physical process changes to avoid the need
for chemicals: Example: Pressure dyeing polyester
eliminates the need for nonbiodegradable dye carri-
ers such as 1,2,4 trichlorobenzene (see Section 4.10,
"Dyeing").
• Altering a product or raw material specification to
avoid the need for chemicals: Example: Finishing cot-
ton knits mechanically at natural width and yield
avoids the need for resins that contain formaldehyde,
which can contribute to hazardous emissions (see
Section 4.12, "Finishing").
• Substituting another process: Example: Pad-batch
dyeing of fiber reactive dyes on cotton eliminates the
need for hard-to-remove salt and reduces hard-to-
treat color (see Section 4.10, "Dyeing").
32
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2.1.2.2 Improved Process Control and
Optimization
With an enhanced understanding of the complex chem-
istry of a particular process and the response of the
process to variables that can be controlled, facilities
often can reduce or eliminate hard-to-treat wastes from
that process. A good example is the reduction of hard-
to-treat color in wastewater. Sections 4.3, "Dyes," and
4.10, "Dyeing," describe how to reduce color by select-
ing dyes of high affinity and controlling bath ratio.
2.1.2.3 Waste Segregation, Capture, and
Reuse/Recycle
In most cases, when a waste is mixed with other wastes, it
loses much of its reuse potential and value. Rather than
allowing them to become mixed with other wastes, hard-to-
treat wastes should be captured in their concentrated forms,
thereby facilitating their reuse. This practice is called "dry
capture" regardless of the physical state of the waste mate-
rial (i.e., solid, liquid, gas, or semisolid sludge). A good
example is the use of centrifugal extraction to remove ex-
cess mothproofing treatment solution from wool substrate.
The concentrated residue removed from the centrifuge is
returned to the process, reducing the amount that ultimately
reaches the environment (see Section 4.12, "Finishing").
Another example is the recovery of caustic from mercerizing
operations (see Section 4.9, "Preparation").
2.1.2.4 Improved Employee Work Practices
Often, workers can reduce the amount of hard-to-treat
chemicals (e.g., dye spillage that produces colored
wastewater) that are wasted if they are made more
aware of prevention measures. The three steps neces-
sary to prevent wastes resulting from employee work
practices are identification, training, and control:
1. Identification: Each chemical that is hard to treat
should be identified to workers.
2. Training: Workers should receive training on han-
dling these chemicals with minimal losses.
3. Control: Worker performance should be audited to
ensure proper control of materials.
2.1.3 High-Volume Wastes
High-volume wastes in textiles include water (especially
washwater from preparation and dyeing stages), alkaline
wastes from preparation, salt, cutting room waste, knitting
oils, and warp sizes. These wastes sometimes can be
reduced by recycle or reuse as well as by process and
equipment modifications. Several methods of reducing spe-
cific high-volume wastes are described in other sections:
• Water: Section 2.2.7, "Water Conservation"
• Salt: Section 2.2.2, "Discharge of Electrolytes"
• >4c/cte and alkali: Various sections (e.g., Section 4.10,
"Dyeing")
• Warp sizes: Section 4.7, "Slashing and Sizing"
In addition, cutting room waste is another major waste
stream that can be reduced. Palmer (3) estimated that
carpet waste amounts to 2 percent of an annual 900
million square yards of production, or 18 million square
yards of waste per year (a value of $100 million). Denim
is another example. Approximately 800 million yards of
denim are produced in the United States each year, at
an average weight of 12 ounces per linear yard. Total
denim production thus amounts to more than one-half
billion pounds per year (4). Fabric utilization efficiency
in cutting and sewing ranges from approximately 72 to
94 percent, and the efficiency for cutting denim is typi-
cally 84 percent or less. Cutting waste, therefore, repre-
sents approximately 16 percent of denim production, or
approximately 100 million pounds annually. Proper de-
sign, planning, information, and communication are es-
sential to managing this waste stream (4).
2.1.4 Hazardous or Toxic Wastes
Hazardous or toxic wastes are a subgroup of hard-to-treat
wastes. Because hazardous wastes have such a substan-
tial impact on the environment, they are discussed as a
separate waste class. In textiles, hazardous or toxic
wastes include materials such as metals, chlorinated sol-
vents, nondegradable surfactants, and a few other nonde-
gradable or volatile organic materials. These materials
often are used for nonprocess applications, such as ma-
chine cleaning. Appropriate reduction strategies include
conservation, substitution, process modification, and
maintenance/housekeeping. Where source reduction is
not possible, such wastes can often be recovered through
recycling. When neither is feasible, however, proper man-
agement and disposal practices must be followed. Specific
examples of hazardous wastes and the sections of this
manual that address them include:
• Air toxics: See Section 2.2.3, 'Toxic Air Emissions."
• Metals: See Section 2.2.5, "Metals."
• Toxic organic materials: See Sections 4.4, "Chemical
Specialties," and 2.2.6, "Aquatic Toxicity."
See also Section 1.2.4, "Hazardous Waste."
2.2 Specific Wastes or Waste Problems
The preceding section discusses generic categories
of wastes to identify the general characteristics of
wastes that make them most amenable to pollution
prevention. This section presents specific examples
for these wastes that are often found in textile proc-
esses and typical pollution prevention strategies appli-
cable for each.
33
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The following sections discuss several specific waste
problems facing the textile industry. The basis for target-
ing these difficulties for discussion is their importance as
unsolved problems of the present or the near future.
Each of the following represents a significant challenge
to the textile industry because the industry now has (or
soon will have) needs that traditional waste treatment
approaches cannot meet. The specific pollution issues
include:
• Color. Section 2.2.1
• Salt: Section 2.2.2
• Air toxics: Section 2.2.3
* Improved treatability of wastes: Section 2.2.4
• Metals: Section 2.2.5
• Aquatic toxlcity: Section 2.2.6
• Water conservation: Section 2.2.7
These sections explain why traditional waste treatment
techniques are (or will be) insufficient to address
these waste issues and why pollution prevention is im-
portant and in many cases represents the only long-term
alternative.
2.2.1 Color Residues in Dyeing Wastewater
Color in effluent from textile dyeing and printing operations
is being increasingly regulated and is widely recognized as
a compliance problem that must be addressed through
pollution prevention (4-8). Effluent from most textile dyeing
operations generally has a dark reddish-brown hue that is
aesthetically unpleasing when discharged to receiving wa-
ters. Although only an aesthetic pollutant,1 color might be
easy to detect (depending on the flow of the receiving
stream), and even trace quantities of commercial textile
colorants in wastewater are readily evident to the naked
eye. Although many methods of color removal exist, none
works in every case (9). Because of the difficulties and
expense in treating color, the best approach for minimizing
color discharges is pollution prevention (6).
2.2.1.1 Measuring Color
Measuring color in textile wastewater is inherently
difficult (9). If the wastewater sample is not filtered,
suspended solids can interfere with transmission meas-
urement, rendering the measurement meaningless. If
the sample is filtered, then the resulting measurement
probably will not reflect the appearance of the wastewa-
ter because the turbidity will have been removed. De-
spite these acknowledged difficulties, the industry uses
several color measurements, including:
Extremely high doses of cotor can interrupt photosynthesis in the
receiving waters, producing impacts beyond the purely aesthetic. Most
textlte effluent, however, is not so severely colored.
• Color: Two methods are available for measuring
color, based on American Dye Manufacturers Institute
(ADM I) and American Public Health Association
(APHA) protocols. Each method measures the color
of light transmitted through a filtered wastewater
sample, resulting in the computed value of a single
number characterizing overall color.
• Turbidity: Turbidity is a measure of the light-scattering
properties of the wastewater. Turbidity is calculated
by comparing the intensity of light scattered by a
sample compared with a reference suspension under
the same conditions.
• Apparent Color: Apparent color is a measurement
that attempts to combine the two measurements
above (color and turbidity).
Because of the extremely high variability of tinctorial
characteristics of dye solutions, generalizations cannot
be made about the amount of dye (in percent or parts
per million [ppm]) that will produce a specific color per-
ception, or color value on the ADMI, APHA, or turbidity
scale. In addition, many color regulations are written in
qualitative language such as "no appreciable change in
the color of the receiving waters" that provides mills with
little guidance on permissible levels in the waste stream.
Thus, color measurement is at best difficult, sometimes
meaningless, and often bears little relation to regulatory
and permit compliance language.
2.2.1.2 Sources of Color in Wastewater
Dyes and pigments from printing and dyeing operations
are the principal sources of color in textile effluent. Dyes
and pigments are highly colored materials used in rela-
tively small quantities (a few percent or less of the
weight of the substrate) to impart color to textile materi-
als for aesthetic or functional purposes (10). In typical
dyeing and printing processes, 50 to 100 percent of the
color is fixed on the fiber (see Table 4-14), and the
remainder is discarded in the form of spent dyebaths
or in wastewater from subsequent textile-washing op-
erations (8).
Reactive dyes are widely used and fall in the lower
range of the fixation scale. As such, they require special
attention to maximize fixation and therefore minimize
waste color discharge. Important factors are bath ratio,
optimized salt use, and adequate time for exhaustion.
These issues are discussed in detail in Sections 4.3,
"Dyes," and 4.10, "Dyeing."
Since the mid-1800s, dye chemists have attempted to
meet consumer demand for color with outstanding per-
manence (i.e., color that is unaffected by crocking [rub-
bing], exposure to light, oxidizing or reducing agents,
attack by chlorine or ozone, hydrolysis, or essentially
any other environmental factor) (4). Their success has
resulted in dyestuffs that have outstanding permanence
34
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and end-use qualities but are largely resistant to treat-
ment or removal in wastewater treatment systems.
Three important ways of preventing and minimizing
color discharges are:
• Maximizing exhaustion from dyebaths.
• Maximizing fixation and minimizing washoff.
• Optimizing dye handling to eliminate spillage, ma-
chine and implement cleanup, and discards.
Maximizing Exhaustion From Dyebaths
To maximize dye exhaust, the dyer must understand the
relationships between exhaust, affinity, and bath ratio,
the three major dyeing process control parameters.2
Although these methods are discussed in much greater
detail in Section 4.10, "Dyeing," the essential points are
reviewed here as well.
Typical values for affinity, bath ratio, and exhaust are:
K (affinity) = 50 to 1,000 for various dye/fiber
combinations
L (bath ratio) = 5 to 50 for various machines (11)
E (exhaustion) = 0.50 to 1.00 (50- to 100-percent
exhaustion) (8)
K (affinity) is a partition coefficient, or the ratio of the
concentration of the dye in solution to the concentration
of the dye in the substrate, at equilibrium, i.e.:
Table 2-2. Typical Exhaustion/Fixation Rates for Dyes of
Various Classes (8)
K = cf
(Eq. 2-1)
where:
cf = concentration of dye in fiber at equilibrium
cs = concentration of dye in solution at equilibrium
An important relationship is:
E = K/(K+L)
(Eq. 2-2)
This equation says that when L increases, E de-
creases and more color is discharged. The effect is
more pronounced on low-affinity dyes (i.e., when K is
low). When K decreases, the dye remains in the solu-
tion and the color in the wastewater increases, espe-
cially if L is high.
Affinity is an important factor in determining dye exhaust
but one that resists generalizations. EEach dye class is
generally applicable to (or has affinity for) specific types
of fibers. Individual dyes within dye classes, however,
can show large variations in affinity. Therefore, "typical"
exhaustion data provide only general guidelines. With
these caveats in mind, typical exhaustion/fixation levels
for various dye types are given in Table 2-2 (8).
Dye Class
Acid
Azoic
Basic
Direct
Disperse
Premets
Reactive
Sulfur
Vat
Typical Ka
130
200
700
100
120
470
50
50
130
Typical
Fixation
(%)
80 to 93
90 to 95
97 to 98
70 to 95
80 to 92
95 to 98
50 to 80
60 to 70
80 to 95
Fibers
Typically
Applied to
Wool, nylon
Cellulose
Acrylic
Cellulose
Synthetic
Wool
Cellulose
Cellulose
Cellulose
This analysis applies only to dyes that do not react (including disperse,
acid, and basic) or to reactive types during the exhaustion phase that
precedes the beginning of the reaction.
The typical K is computed by assuming a bath ratio of 17:1 (typical
for becks) and solving for K = EL / (1 - E), where E is on a O-to-1
scale. For acid dyes, the dye exhausted is typically 87 percent, or
E = 0.87. Solving E = K/(K + L) for K results in K = L/(1 - E) =
(17)7(0.13), or 130. Therefore, at equilibrium, the concentration of
dye in the fiber is 130 times greater than the concentration of dye
in the bath for a dye that exhausts 87 percent at 17:1 bath ratio.
As seen in the table, cellulose dyes typically have poor
exhaustion and fixation characteristics. The popular fiber
reactive dye classes exhibit the poorest fixation. The
same conclusions are reflected in Table 2-3, which
shows wastewater color values from processes using
different types of dyes (5). More recent data would no
doubt show improvements in exhaust ratios for some dyes.
Maximizing Fixation and Washoff
Fixation and afterwashing are important steps in dyeing
and have substantial bearing on the levels of residual
color in textile wastewater. Many methods are used for
fixing dyes, including chemical insolublization of the dye
by oxidation or coupling (vat, sulfur, and naphthol dyes),
chemical reaction of the dye with the fiber to form a
covalent bond (fiber reactive dyes), reaction of the dye
with the fiber to form an ionic bond (acid and basic
dyes), formation of solid solution (disperse dyes), and
the use of fixative agents (direct and fiber reactive dyes).
These methods generally provide good fixation for most
dye classes (acid, basic, disperse, direct, vat, sulfur, and
naphthol). For fiber reactive dyes, however, fixation is often
less than 75 percent. The problem of fiber reactive dyes is
discussed in detail in Section 2.2.1.3.
Washing is an important step in determining final product
quality and is discussed in greater detail in Section 2.2.7,
'Water Conservation." Especially important for minimizing
color carryover is the role of bath ratio in drop/fill wash
procedures and the control of flow and mixing in overflow
washing. Special methods such as countercurrent washing
can also reduce color in addition to providing other benefits.
35
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Table 2-3. Wastewater Color Values Derived From Different Combinations of Dyes, Substrates, and Dyeing Equipment (5)
Dye
1
Z
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Number and Class
Vat
2:1 Preinetallized
Disperse
After coppered direct
Reactive
Disperse
Chrome
Baste
Disperse
Acid
Direct
Developed
Disperse/Acid/Basic
Disperse
Sulfur
Reactive
Vat/Disperse
Basic
Disperse/Acid/Basic
Azoic
Substrate
Cotton
Polyamide
Polyester
Cotton
Cotton
Polyamide carpet
Wool
Polyacrylic ,
Polyester carpet
Polyamide
Rayon
Rayon
Polyamide carpet
Polyester
Cotton
Cotton
Cotton/Polyester
Polyester
Polyamide carpet
Cotton
Method
Exhaust/Package
Exhaust/Beck
Atmospheric exhaust
Exhaust/Beck
Exhaust/Beck
Exhaust/Beck
Exhaust/Beck
Exhaust/Beck
Exhaust/Beck
Exhaust/Beck
Exhaust/Beck
Exhaust/Beck
Exhaust/Beck
High-temperature exhaust
Continuous
Continuous
Continuous
Atmospheric exhaust
Continuous/Kuster
Exhaust/Package
ADMI
Color
1,910
370
315
525
3,890
100
3,200
5,600
215
4,000
12,500
2,730
210
1,245
450
1,390
365
1,300
<50
2,415
ADMI
Apparent Color
—
—
—
1,280
—
—
—
12,000
315
—
—
—
720
—
—
—
1,100
2,040
190
— —
Optimizing Dye Handling, Equipment Cleaning, and
Housekeeping Techniques
In addition to selecting dyes and dyeing methods that
promote maximum dyebath exhaustion, proper work
practices in the mix kitchen, cleaning operations, sched-
uling, and other factors are important for reducing efflu-
ent color. Best management practices for these aspects
of textile operations are described fully in Sections 3.8,
"Maintenance, Cleaning, Nonprocess Chemical Con-
trol," 3.14, "Scheduling Dyeing Operations To Minimize
Machine Cleaning," and 4.18, "Support Work Areas."
2.2.1.3 Fiber Reactive Dyeing
Poor fixation has been a longstanding problem with fiber
reactive dyes (12), and batch dyeing with fiber reactive
dyes represents perhaps the greatest challenge to the
textile industry in terms of minimizing color discharge.
Considerable research and development on this issue
are now underway. Mill dyers must understand the fun-
damental principles behind fiber reactive dye fixation
efficiency and their relationship to color discharges.
Typical fiber reactive batch dyeing processes include
"two-step" and "all-in" processes. General procedures
are shown in Table 2-4. In the two-step procedure, the
dyeing process runs in a reversible exhaustion mode
until alkali is added, at which time the dye starts react-
ing. Because the dye is more exhausted at the onset of
the reaction, it is more likely to react with fiber. In the
all-in process, no initial exhaustion occurs, and the en-
tire dyeing process is a nonreversible, simultaneous
diffusion and first-order reaction. The all-in process re-
sults in lower percentage fixation and, therefore, more
color in the wastewater.
Bireactive "double-anchor" dyes, which are now being
promoted to reduce wastewater color even when ap-
plied by the two-step process, do not achieve the full
expected fixation from the second reaction because
Table 2-4. Comparison of Steps in Alternative Dyeing
Procedures for Fiber Reactive Dyes
Two-Step
Fill machine
Set bath
Load fabric
Add dye
Start heating
Add salt
Attain dyeing temperature
Run 10 minutes
Add alkali
All-in
Fill machine
Set bath
Load fabric
Add dye
Add salt
Add alkali
Start heating
Attain dyeing temperature
Run 30 to 45 minutes
Hot patch decision
If okay, wash
Cold patch decision
Drop bath and unload
Run 30 to 45 minutes
Hot patch decision
If okay, wash
Cold patch decision
Drop bath and unload
36
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almost all the first-dye hydrolysis occurs in the solution.
Therefore, the second reaction is always similar to the
all-in process.
The key to high fixation (and less color in wastewater)
in batch dyeing of fiber reactives is to get high exhaus-
tion by:
• Using high-affinity dyes.
• Using low-bath-ratio dyeing machines.
• Achieving maximum exhaustion before adding alkali.
• Allowing sufficient time for full fixation.
• Using optimized temperature, salt, and alkali concen-
trations.
For some dyes, particularly "vinyl suilfone" types that
react by the Michael addition mechanism, the activation
energy for hydrolysis is not as great as the activation
energy for the reaction with cellulose. Therefore (based
on the Arrhenius equation), raising the temperature on
these dyes causes hydrolysis to increase in rate faster
than the reaction with cellulose, leading to more hydroly-
sis. The triazines, on the other hand, react by a nucleo-
philic substitution reaction (not addition) and thus have
the same activation energy for water and for cellulose.
As a result, temperature is not as significant in terms of
color discharges.
Factors Affecting Fixation of Fiber Reactive Dyes
The fixation of fiber reactive dyes is influenced by many
factors, including fiber shape, bath ratio, dye partition co-
efficient (affinity), and reaction rate constant. Although
these factors interact in complex ways, evaluating the role
of each parameter listed above is possible. The standard
theoretical analysis is in terms of fixation efficiency (E),
which should be maximized to reduce color in wastewater.
Fixation efficiency is an extremely complex, widely mis-
understood subject. Theoretical models can be set up,
but these models are based on primitive assumptions
(e.g., infinite plane slab of substrates) to simplify the
differential equations and boundary conditions. Even in
simplified cases, the resulting differential equations
sometimes cannot be easily solved. The problem of
estimating fixation relates to simultaneous diffusion and
first-order kinetics reactions (13). Despite these difficul-
ties, equations and data verified by experiments show
that three main factors are important. (A fourth factor,
fiber shape, is also important, but is not controllable.)
The three main factors that influence fixation efficiency
of fiber reactive dyes are:
• Process design (two-step versus all-in)
• Dye affinity/low-bath-ratio/maximum exhaustion
• Dye reactivity
Although many different kinds of fiber reactive dyes
exist, they all involve two competing reactions:
Dye + water = hydrolyzed dye (washes away as
color in wastewater)
Dye + fiber = desired colored textile material
Fixation efficiency is the ratio of the dye fixed (desired
reaction) to the dye hydrolyzed (undesired reaction)
(13). A fairly straightforward kinetic analysis leads to the
following equation:
[Os]
D Rf[CeHCT]
(Eq. 2-3)
{OH-}
where:
E = fixation efficiency
S = fiber shape factor (fixed)
L = bath ratio
[D{]/[DS] = instantaneous partition, a factor
similar to K above
D = diffusion coefficient, related to K
k'n = dye reaction rate constant
Rf = ratio of reaction rate constant with
cellulose to reaction rate constant
with water, usually a constant
approximately equal to 1
[CellCT]/[Ol-n = ratio of ionization constants of
cellulose to water, usually
approximately 30:1 (cellulose ionizes
approximately 30 times more
completely than water)
In a typical dyeing, S, L, Rf are constant. K and k' are
known or can be determined for each dye, and D can
be estimated from a graph of log K versus log D (13) to
be a constant multiplied by K1/2. Based on this, and
lumping all the constant (fixed) terms into one, the fol-
lowing relationship can be obtained:
Efficiency of fixation = (A constant) * (K1/3)/(k1/2)
(Eq. 2-4)
This relationship is shown in Figure 2-1.
Using Conventional Fixatives
Standard practice in direct dyeing is to use dye fixatives
to improve the resistance of direct dyes to washoff in the
afterwashing steps, as well as in fastness tests. The use
of fixatives, however, is not as prevalent on fiber reactive
shades, except in yarn dyeing. Fixatives are effective on
fiber reactive dyes, however, and can cause the fixation
of hydrolyzed color, which otherwise would wash off.
Thus, fixatives can reduce the amount of color in waste-
water.
2.2.1.4 Pollution Prevention Strategies
A mill can take many actions to reduce color in waste-
water. Each of these actions uses process optimization
37
-------
Figure 2-1. Relationship between affinity, reactivity, and fixa-
tion efficiency.
to achieve the highest possible fixation (8). The strate-
gies for achieving high fixation vary depending on
whether batch or continuous dyeing is performed be-
cause better fixation in batch dyeing is related to a
combination of exhaustion and fixation, while in continu-
ous dyeing it is usually related only to fixation.
Batch Dyeing
Because of the high k values for dyeing of synthetic fibers
and wool, the main problems with color in effluent result
from cotton dyeing. In the general design of cellulosic
batch dyeing processes, the most important factors are to:
• Ensure a good cloth preparation.
• Use a low bath ratio.
• Select high-affinity dyes.
• Optimize pH and salt, if used, for each recipe.
• Use proper time-temperature profile relationships.
• Avoid auxiliaries that retard or reduce exhaustion.
• Minimize the use of auxiliaries and surfactants.
• Avoid adding more chemicals (e.g., defoamers) to
offset the undesired side effects of other chemicals
in favor of nonchemical alternatives (e.g., procedural
or mechanical remedies, or changing the dye selec-
tion or the product itself).
For fiber reactive dyes (the worst offender of poor fixation):
• Use two-step dyeing for fiber reactive, not all-in.
• Use fixatives for fiber reactive (as well as direct).
• Ensure maximum fixation by proper sequencing of
events: (1) use high-affinity dyes and low-liquor ratio,
(2) optimize factors such as salt and temperature for
each recipe, (3) maximize dyebath exhaustion before
adding alkali, and (4) use bireactive dyes.
Continuous Dyeing/Printing
As in batch dyeing, the key to minimizing color dis-
charges in continuous dyeing or printing operations is to
maximize fixation, which occurs mainly through steam,
thermofixation, or chemical agents. The proper dwell
time and temperature in the steamer or thermofixation
oven is essential. Also, the presence of air (oxygen) in
steamers can oxidize vat dyes prematurely and lead to
excessive washoff.
Also, making up only the amount of dye solution or print
paste actually needed is equally important so that no extra
solution or paste remains to be discarded at the end of the
run. Discards and pad dumps are the main source of color
in wastewater from continuous dyeing and printing.
Printing is an inherently messy operation, so housekeep-
ing practices can have substantial bearing on overall color
discharges. Paste handling and cleaning of mixers, ho-
mogenizers, screens, and squeegees should be closely
controlled. Drums of print paste or "empty" drums of chemi-
cals should not be washed out into the drain. Residues
should be drained only into the next drum to be opened. If
paste is left over (which it should not be), it should be
reused or added to when making up a future (usually
brown or black) color recipe. If using leftover paste in a
future recipe is impossible, the paste should be scooped
up, dried, and then landfilled as a solid material.
Work Practices/Scheduling
The following work practices in the drug room or color
kitchen are part of an effective pollution prevention strat-
egy (11):
• Use of intermediate bulk containers, or IBCs.
• Dry capture (vacuum).
• Avoiding powder spills.
• Minimizing implement washup by using different dip-
pers for each chemical or using automatic chemical
dispensing.
2.2.2 Discharge of Electrolytes
Many types of salt are either used as raw materials or
produced as by-products of neutralization or other reac-
tions in textile wet processes (see Table 2-5). Several
authors have identified salt in textile-dyeing wastewater
as a significant future problem area (8). Typical cotton
batch dyeing operations use quantities of salt that range
from 20 percent to 80 percent of the weight of goods
dyed, and the usual salt concentration in such wastewa-
ter is 2,000 ppm to 3,000 ppm (14). Regulatory limits
imposed on textile facilities and on publicly owned treat-
38
-------
Table 2-5. Types of Salt Used in Textile Operations and
Toxicity Characteristics
Salt Type
Calcium chloride
Common salt
Epsom salt
Glaubers salt
Magnesium chloride
Potassium chloride
Typical
Use
Formed
Dyeing
Fixing
Dyeing
Catalyst
Formed
Typical
. Aquatic Mammalian
TLmg6 Oral Toxicity
(ppm) LD50 (mg/kg)a
>1,000a
2,000b
NA
NA
NA
1,000- 100a
3,500
3,000
3,000
6,000
8,100
7,000
* From Sax (15)
"From Herlant(16).
ment facilities (POTWs) that receive textile wastewater
start at 250 ppm (see Section 2.2.2.3).
The removal of salt from mixed textile wastewater to
reduce chloride concentration from 3,000 ppm to 250
ppm is extremely difficult and expensive by any known
treatment method. Therefore, reducing salt concentra-
tions through pollution prevention measures is the only
practical alternative to solve the dilemma presented by
this hard-to-treat, toxic, high-volume waste.
This section considers mainly the chloride and sulfate
salts of sodium, potassium, and magnesium. Certain
specific organic anions and miscellaneous inorganic
anions, as well as salts of the "heavy" metals, are dis-
cussed in more detail in other chapters. Common salt
(sodium chloride) and Glaubers salt (sodium sulfate)
constitute the overwhelming majority of total salt use.
Other salts used as raw materials or formed in textile
processes include Epsom salt (magnesium chloride),
potassium chloride (from potassium hydroxide), and
others in low concentrations. Although the mammalian
and aquatic toxicities of these salts are very low, their
massive use in certain textile-dyeing processes can
produce wastewater that is well above the toxic limit.
2.2.2.1 Sources of Salt in Wastewater
The type and amount of salt used in dyeing processes
is dictated by cost, corrosion considerations, the type of
dyeing machine used, bath ratio, type of dye, and fiber
being dyed. Common salt is the cheapest at about $0.04
per pound compared with $0.10 for Glaubers salt, but it
is more corrosive to equipment and, therefore, some
dyers prefer Glaubers salt. Also, Glaubers salt gives
brighter shades with certain dyes.
In addition to the use of salt as a raw material, many
reactions in textile wet processing produce salt as a
by-product. In one case study (17), a moderate-sized
mill, dyeing about 400,000 pounds per week of cotton
knit fabrics, used substantial amounts of the major pro-
duction acids and alkalis over a 6-week period. Quanti-
ties are shown in Table 2-6. These acids and alkalis
ultimately reacted in the waste stream either with each
other or with pH neutralization chemicals added in waste
treatment to produce well over 50,000 pounds of salts
plus a pH value of over 10 in about 200 million liters of
water. Thus, the wastewater contained neutralization
salts from just these top six acids and alkalis of about
60 ppm (17). In addition, many other chemical reactions
that occur in textile processes produce salts. Table 2-7
lists some examples.
Many textile dyes and specialty chemicals also contain
salt. Most notably, salt acts as a diluent in commercial
dyes, and a typical direct or fiber reactive dye may
actually be 20 to 70 percent salt.
2.2.2.2 Use of Salt in Dyeing Processes
Salt serves many functions in the dyeing process, and
the literature has described its action in many ways.
Generally, salt is used to assist the exhaustion of ionic
Table 2-6. Typical Amounts of Salt Used or Generated in
Textile Operations (17)
Acid or Alkali
Amount (pounds)
Acetic acid
Caustic 35%
Caustic 50%
Soda ash
Sulfuric acid
TSPa
16,200
27,520
10,815
4,500
2,854
5,800
a TSP = trisodium phosphate.
Table 2-7. Types of Salt Discharged From Various Process
Sources
Process Source
Type of Salt Introduced Into
Wastewater
Diazotization of dyes
Dyeing pH control
Incoming fiber
Hypochlorite bleaching
Ion exchange filters
Process water from source •
Reduction clearing (hydro)
Sodium chlorite stripping
Triazine reactive dyeing
Vat dye oxidation
Vinyl sulfone reactive dyeing
Water conditioning
Sodium nitrate
Ammonium sulfate, common
salt, glaubers salt, acetate and
formate salts
Common salt, other chlorides
Calcium chloride
Glaubers salt, common salt
Common salt, calcium chloride,
and magnesium chloride
Sodium sulfate
Common salt
Common salt
Sodium iodide
Glaubers salt
TSPPa
TSPP = tetrasodium phosphate.
39
-------
dyes, particularly anionic dyes such as direct and fiber
reactive dyes on cotton. Salt has many effects in the
direct dyeing of cotton (13):
• Increases ionic strength of the dyebath
• Increases dye affinity for cellulose fiber
• Alters the dye diffusion coefficient
• Disrupts hydration of anionic dyes
• Disrupts hydration of cellulosic dye sites
* Increases potential for dye interactions (e.g., aggregation)
• Offsets fiber's negative zeta potential
• Provides electrical neutrality through counter/co-ions
* Salts out anionic dye by common ion effects
Figure 2-2 illustrates how salt addition can increase
dyebath exhaustion. For Colour Index (Cl) Direct Yellow
12, raising salt concentrations from 0.5 grams per liter
to 4 grams per liter causes dyebath equilibrium exhaus-
tion to increase by an order of magnitude (18).
2.2.2.3 Regulatory Status
The U.S. EPA has published national water quality
criteria for chlorides, recommending that the 4-day av-
erage concentration of dissolved chloride (when associ-
ated with sodium) should not exceed 230 milligrams per
liter more than once every 3 years and the 1-hour con-
centration should not exceed 860 milligrams per liter
more than once every 3 years on average (19). States
(or EPA) use this guidance to establish limits on a per-
mit-by-permit basis through the National Pollutant Dis-
charge Elimination System (NPDES). The federal
criterion is for an instream concentration, so the limits on
final effluent established in NPDES permits depend on
Curve
2.5 5.6
Dyebath Concentration (g/L)
7.5
Figure 2-2. Adsorption Isotherms of Chrysophenine G on cel-
lulose sheet at 40°C and varying salt concentra-
tions (see legend) (18).
factors such as the discharge flow, stream classification,
the size of the receiving water (instream waste concen-
tration or dilution factor), and the number of dischargers.
Depending on the factors listed above, textile mills typi-
cally must meet POTW pretreatment limits or NPDES
chloride permit limits of 250 ppm and upward (20).
2.2.2.4 Pollution Prevention Practices for Salt
Reduction
To reach new instream limits for chloride of 250 ppm, mills
need to initiate significant pollution prevention efforts on
several fronts (21). Salt is cheap and effective and has low
toxicity. As a consequence, mills often misuse or overuse
salt (21). Salt is also very versatile; thus, a major research
breakthrough would likely be required to find another
chemical that could perform all the functions of salt at
comparable cost and with lower toxicity.
Despite the difficulties apparent in eliminating salt, sev-
eral approaches to reducing salt, specifically from cotton
dyeing, are available. These should be examined
closely in light of tightening limits for chloride in textile
effluent. The general principles to follow to minimize salt
use are listed below, and several are discussed in more
detail in the paragraphs that follow. Each principle en-
tails tradeoffs that should be understood before imple-
menting them as possible solutions:
• Use the lowest practical bath ratio in batch dyeing.
• Optimize salt use individually for each dyeing (as op-
posed to standard procedures used for all batches or
runs).
• Consider continuous dyeing pad-batch dyeing proc-
ess alternatives.
• Minimize discards and production color changes in
continuous dyeing and printing.
• Design and make products from fibers other than cotton.
• Reuse batch dye baths.
• Ensure proper handling of dyes and fabrics.
• Select dyes that exhaust with minimum salt.
• Optimize dyeing temperature individually for each recipe.
• Inform fashion designers which colors and fabrics have
high associated environmental loads (due to salt use)
and work to find alternatives that avoid these impacts.
Low Bath Ratio
In recent years, machine manufacturers have tended
toward lower bath ratio dyeing systems for energy con-
servation as well as chemical savings. Ultra low liquor
ratio (ULLR) dyeing systems are discussed in detail in
Sections 3.19, "Pollution Prevention Through New
Equipment," and 4.10, "Dyeing."
40
-------
Batch dyeing at low bath ratios in these machines con-
serves salt because salt use is based on the amount of
dyebath present (owb), rather than the weight of the
fiber or the goods (owf or owg).3 The rule is: owb times
the bath ratio equals owg. For example, in a 5:1 bath
ratio ULLR dyeing machine, 50 grams per liter of salt is
25 percent owg, but at 40:1 bath ratio in a hosiery dyeing
machine, the same 50 grams per liter salt is 200 percent
owg. In each case, the salt is the same (i.e., 50 grams
per liter owb). Types of dyeing machines vary greatly in
their bath ratios, as shown in Table 2-8, which translates
into different salt requirements.
Table 2-8. Salt Requirements of Various Dyeing Machines (11)
Machine
Garment
Paddle
Skein, beck
Jet, stock
Beam, package
Low bath jet
ULLR, jig
Bath Ratio
50
40
17
12
10
8
5
Salt Required
(pounds)8
2,500
2,000
850
600
500
400
250
Pounds of salt required per typical 1,000-pound production lot to
produce 50 gal/L bath concentration.
Each of the above batch dyeing systems has its own
limitations and range of applicability to particular sub-
strates and styles. Continuous and pad-batch dyeing of
fiber reactives on cotton can completely eliminate the
need for salt, but certain other restrictions and limitations
apply in terms of economics as well as the types of
substrates that can be handled (22). The topic of pad-
batch dyeing is fully reviewed in Section 4.10, "Dyeing."
Continuous methods are discussed in Section 3.10,
"Process Alternatives."
Individual manufacturers' batch dyeing machines vary
slightly within the generalization above. All batch ma-
chines should be filled consistently to a fixed volume of
dyebath, and the weight of goods loaded should be the
same for each dyeing. Otherwise, the bath ratio will vary,
leading to poor shade repeats and other problems. This
may seem elementary, but dyehouses often do not spec-
ify the fill level for the machine and, therefore, do not fill
machines consistently. Variable lot sizes are also encoun-
tered because of variation in customers order sizes. The
net effect is an undesirable variation in berth ratio.
Because salt has essentially no affinity for cellulose cotton fibers and
therefore does not exhaust onto the fiber, the amount of salt should
be computed based on the owb. Other dyebath components (e.g.,
dyes, softeners, lubricants) that do have definite affinity for the fiber,
and therefore do exhaust, are always based owf or owg in batch
dyeing processes.
. The same types of consideration noted above appfy not
only to salt but also to all additives that act primarily on
the bath (e.g., buffers, surfactants).
Optimized Salt
Each dye class requires characteristic amounts of salt,
and dyes within a class exhibit wide variances. In gen-
eral, the salt requirements for batch dyeing of cotton with
various dye classes are as shown in Figure 2-3 (7).
Requires More Salt
Hot Dyeing Rber Reactive
Cold Dyeing Fiber Reactive
Direct
Vat
Sulfur
<
Requires Less Salt
Figure 2-3. Salt requirements for various dye classes—batch
dyeing of cotton (7).
Table 2-9 shows the amount of salt required to achieve
50-percent exhaust with a selection of direct dyes (18).
Because of the variety in dye classes, no optimal amount
of salt applies for all dyes and situations. Therefore, gen-
eralizations such as those shown in Table 2-10 may actu-
Table 2-9. Salt Required to Produce 50-Percent Exhaustion
of Direct Dyes (18)
Dye
Salt Addition for 50% Exhaustion
(% owf)
Chlorazol Brown MS
Benzopurpurine 10B
Benzopurpurine 4B
Chlorazol Dark Green PLS
Diazo Black OT
Melantherine BH
Chlorazol Green GS
Chlorazol Fast Yellow 5GKS
Oxyphenine GG
Primuline AS
Trisulphon Brown B
Chlorazol Fast Pink BKS
Diphenyl Brilliant Orange GR
Durazol Red 2BS
Benzo Fast Helio 4BL
Chlorazol Fast Eosine B
Benzo Fast Yellow RL
Benzo Fast Yellow 4GL
Chrysophenine G
Rosanthrene Pink
Rosanthrene Violet 5R
0
0
0.2
0.4
1.0
1.0
1.2
2.0
2.0
2.0
2.0
2.0
4.0
5.0
4.5
7.0
8.5
8.5
13.0
16.0
30.0
41
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Tabla 2-10. Typical Salt Application for Direct and Reactive
Dyes on Cotton (16)
Shade
Pastel/Light
Medium
Dark
Dye owf
<1.5%
1.0-2.5%
>2.5
Direct
2.5-7.5 g/L
7.5-12.5 g/L
12.5-20.0 g/L
Reactive
30-60 g/L
70-80 g/L
80-100 g/L
ally waste salt because recipes of some specific dyes
may require significantly less salt. Each individual recipe
should be optimized based upon controlled experimen-
tation or analysis of production data. Typical salt-use
practices for batch dyeing of cotton with direct and fiber
reactive dyes are similar to those shown in Table 2-10
(16).
Another complication is that cost systems and comput-
erized batch recipe programs often attempt to base all
of the chemicals in the process owg. This is convenient
from a cost accounting point of view but can lead to
problems, for example, when the bath ratio varies due
to fluctuations in lot size. If the salt is specified owg and
the bath ratio varies, then the salt concentration owb will
fluctuate, leading to poor shade repeats and environ-
mental problems. A fixed amount of salt owg uses too
much salt owb when bath ratio is low, or insufficient salt
owb when bath ratio is high, leading to excessive color
in the wastewater.
In response to the need to minimize salt, most major
cotton dye manufacturers have active research and de-
velopment programs to develop no- or low-salt exhaust
dyeing systems. Hoechst Celanese has set a technical
goal of reducing salt requirements to 25 grams per liter
in the dyebath, while achieving dye fixation of 90 percent
in exhaust dyeing of fiber reactive dyes (12). This is up
to a 75-percent reduction compared with current com-
mercial practice, which is to use up to 100 grams per
liter of salt with fixation levels of 50 to 90 percent. The
use of less salt generally provides lower exhaustion and,
thus, more color pollution in wastewater.
Process Design
A major control point for salt is product, process, and
machine selection. Selecting alternatives that allow for
reduced salt use can, however, involve tradeoffs. If
batch dyeing of cotton is selected, then simply reducing
salt concentration in the dyebath generally results in the
negative environmental consequence of increased color
in wastewater and also results in poor shade repeats.
The classes that require the least salt (i.e., vat, sulfur,
and naphthol) are more often used for continuous dye-
ing and are somewhat more difficult for batch dyeing
than fiber reactive and direct types. In addition, the range
of colors that can be produced with either vat, sulphur,
or naphthol is more limited.
Finally, each dye class that allows for reduced salt use
has its own particular problems, for example:
• Fiber reactive dyes: Massive salt requirements; color
in wastewater.
• Direct dyes: Less salt and color residue but limited
color shade range and fastness properties.
• Vat dyes: Offensive oxidizing/reducing agents re-
quired; limited shade range.
• Sulfur dyes: Sulfide in wastewater; limited shade range.
• Naphthols: Offensive organic compounds; limited
shade range.
Each individual direct dye has a temperature of maxi-
mum affinity. Therefore, maximum exhaust with mini-
mum salt occurs at a specific temperature (23). Few if
any dyers actually set the final exhaustion temperature
based on the optimum for a particular recipe, even
though that is not difficult with modern microprocessor
controllers. Table 2-11 gives optimum exhaust tempera-
tures for over 100 direct dyes (23). Using these tempera-
tures not only produces maximum exhaust with mini-
mum salt use but also ensures consistent shade repeats
and better quality.
Product Design
Of course, fabric can be designed and produced from
synthetic or woolen fibers, in which case salt use is very
low or insignificant compared with batch dyeing of cot-
ton. The tradeoff is the sacrifice of the comfort and
aesthetics of cotton, plus the likely introduction of or-
ganic chemicals, dye carriers, levelers, and retarders
required for other fibers. This may not be a viable option
in all cases, but the important point is that fabric design-
ers and fashion colorists should be made aware of the
environmental loads associated with the selection of all
types of fabrics and color ranges.
Handling
Because of the low cost of salt, substantial amounts
tend to be spilled, wasted, and washed down floor drains
without much thought to the consequences. Although
proper salt handling practices do not completely solve
the problem, they should be addressed as part of a
pollution prevention strategy. Storage of salt near high
traffic areas or where water can spill on the bags fosters
waste and should be avoided where possible. One of
the best solutions to this problem is to use bulk salt
systems or intermediate bulk containers (IBCs). Salt is
readily available in IBCs, which are less susceptible to
breakage during handling and which produce less pack-
aging waste. Whenever salt or any other powder or
granular chemical is spilled, it should be vacuumed up,
not washed down the drain.
42
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Table 2-11. Maximum Affinity Temperature of Commercial
Dyes (23)
Table 2-11. Maximum Affinity Temperature of Commercial
Dyes (23) (Continued)
Dye Name
Yellows
Yellow 4
Yellow 6
Yellow 7
Yellow 8
Yellow 11
Yellow 12
Yellow 19
Yellow 20
Yellow 26
Yellow 27
Yellow 28
Yellow 29
Yellow 44
Yellow 50
Yellow 106
Oranges
Orange 1
Orange 8
Orange 15
Orange 26
Orange 29
Orange 34
Orange 37
Orange 39
Orange 102
Reds
Red 1
Red 2
Red 7
Red 10
Red 16
Red 17
Red 20
Red 23
Red 24
Red 26
Red 28
Red 31
Red 32
Red 37
Red 39
Red 72
Red 75
Red 76
Red 79
Red 80
Red 81
Red 83
Red 153
Violets
Violet 1
Violet 9
Virtlat OO
vioiet d.d.
Violet 47
Violet 48
Chemical
Type8
1,5
5
4
1,4
5
1,5
1,5
1
1
1,4
1,4
1,4
1
1
5
1
1
1
1
1,5
1,5
1,5
1
1
1
1
1
1
1
1,4
1
1
1
1
1
1
1
1
1
1,5
1
1
1
1
1
1
1
1
1
Commer-
cially
Available?
Yes
Yes
—
Yes
Yes
Yes
—
—
—
Yes
Yes
Yes
Yes
Yes
Yes
—
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
—
—
Yes
—
—
Yes
Yes
Yes
Yes
Yes
—
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Molecular
Weight
624
470
591
530
474
680
680
554
584
662
680
946
634
1,004
—
642
635
416
804
870
753
783
739
870
651
772
804
745
685
745
657
861
950
1,010
744
761
—
700
728
1,009
1,038
813
1,096
1,420
699
11,068
714
776
715
Q/t Q
B4o
1,048
979
Maximum
Affinity
—
—
—
—
70
40
—
—
50
35
80
100
50
60
95
50
70
80
80
80
80
100
80
—
90
80
80
80
60
50
60
90
100
100
80
50
—
80
80
100
80
100
90
100
60
100
60
100
40
90
100
Dye Name
Violet 51
Violet 66
Blues
Blue 1
Blue 6
BlueS
Blue 14
Blue 21
Blue 25
Blue 26
Blue 27
Blue 55
Blue 67
Blue 71
Blue 75
Blue 76
Blue 78
Blue 80
Blue 86
Blue 98
Blue 106
Blue 108
Blue 120
Blue 218
Greens
Green 1
Green 6
Green 8
Green 11
Green 26
Green 28
Browns
Brown 1
Brown 2
Brown 6
Brown 25
Brown 29
Brown 31
Brown 58
Brown 74
Brown 95
Blacks
Black 3
Black 4
Black 9
Black 22
Black 38
Black 51
Black 56
Black 74
Black 80
Black 91
Black 166
Chemical
Type8
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
3
3
1
1
1
1
1
1
1
1,6
1
1
1
1
1,5
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
a 1 = azo; 2 = phthalocyanine;
6 = anthraquinone.
Commer-
cially
Available?
Yes
Yes
Yes
Yes
—
Yes
__
Yes
—
__
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
—
—
Yes
Yes
Yes
Yes
—
Yes
Yes
—
Yes
Yes
Yes
—
Yes
—
- —
Yes
Yes
Yes
3 = dioxazine;
Molecular
Weight
743
951
1,040
980
806
1,008
891
1,010
1,102
876
921
907
1,125
1,127
1,040
1,127
—
779.5
971
741
898
949
1,040
791
836
902
788
1,344
992
680
651
682 .
991
946
1,165
679
1,886
698
567
819
816
1,131
805
665
947
1,227
978
926
—
4 = thiazole; 5
Maximum
Affinity
.40
—
70
60
90
70
90
70
100
80
80 •
90
100
70
95
100
—
100
—
—
—
95
80
80
80
60
100
80
100
70
100
90
100
80
100
100
90
100
100
—
40
80
100
90
—
= stilbene;
43
-------
Batch Dye Bath Reuse
In some cases, batch dye baths can be reused, thus
eliminating the need for additional salt except the small
amount (about 10 percent) that is carried out with the
wet dyed fabric. The subject of dyebath reuse is re-
viewed in Section 4.10, "Dyeing."
2.2.3 Toxic Air Emissions
Textile operations involve numerous sources of air emis-
sions, and these sources give rise to a variety of air
quality issues. Unit operations that present the greatest
concern are coating, finishing, and dyeing (24). The
textile industry is a relatively minor source of air pol-
lutants compared with other industries, but the industry
emits a great variety of materials, making sampling,
analysis, treatment, and prevention more complex (25).
2.2.3.1 Regulation
Air pollution from textile operations is not a new problem,
but it has recently received increased attention. Title III
of the 1990 Clean Air Act Amendments (CAAA) deals
with airtoxics, and will have a major impact on the textile
industry. Title III identifies 189 hazardous air pollutants
(HAPs) for which EPA is required to develop regulations
(see Table 2-12). Specific HAPs emitted from textile
processes, and their sources, are identified in Table
2-13. In addition to EPA, states also are developing
regulations for air emissions. For example, the state of
North Carolina has developed a list of 158 air pollutants
to be regulated (26).
Because of emissions of nitrogen and sulfur oxides
(NOx and SOx) from boilers, many textile plants are
likely to be classified as "major sources" under Title III
(i.e., sources that emit more than 25 combined tons per
year of all listed HAPs). Although boiler emissions of
NOx and SOx are the main sources of high-volume
emissions, being classified as a major source will force
textile plants to adopt controls for all emissions, includ-
ing production and maintenance chemicals. The
amounts of these materials emitted are low in most
cases, however, and the economical approach is to
reduce them as much as possible using pollution pre-
vention practices.
Title III covers area sources of emissions as well as
point sources. The CAAA's Maximum Achievable Con-
trol Technology (MACT) standards will likely require
control technologies for the textile industry but the
specifics of these technologies are still unknown.
MACT is expected to include not only treatment meas-
ures but also pollution prevention measures such as
chemical substitution, process changes, and capture
of pollutants from processes, storage tanks, and
fugitive sources. For some facilities, the expense of
capture and treatment equipment will be immense.
Table 2-12. Initial List of 189 Hazardous Air Pollutants
Identified in the Clean Air Act Amendments of
1990 (28)
No. CASa No.
Pollutant
1 75070 Acetaldehyde
2 60355 Acelamide
3 75058 Acetonitrile
4 98862 Acetophenone
5 53963 2-acetylaminofluorene
6 107028 Acrolein
7 79061 Aorylamide :
8 79107 Acrylic acid
9 107131 Acrylonitrile
10 107051 Allyl chloride
11 92671 4-aminodiphenyl
12 62533 Aniline
13 90040 o-Anisidine
14 1332214 Asbestos
15 71432 Benzene (including benzene from
gasoline)
Benzidine
Benzotrichloride
Benzyl chloride
Biphenyl
Bis(2-ethylhexyl)phthalate (DEHP)
Bis(chloromethyl)ether
Bromoform
1,3-Butadiene
Calcium cyanamide
Caprolactam
Captan
Carbaryl
Carbon disulfide
Carbon tetrachloride
Carbonyl sulfide
Catechol
Chloramben
Chlordane
Chlorine
Chloroacetic acid
2-chloroacetophenone
Chlorobenzene
Chlorobenzilate
Chloroform
Chloromethyl methyl ether
Chloroprene
Cresols/Cresylic acid (isomers and
mixture)
43 95487 o-Cresol
44 108394 m-Cresol
45 106445 p-Cresol
46 98828 Cumene
47 94757 2,4-D, salts and esters
48 3547044 DDE
49 334883 Diazomethane
50 132649 Dibenzofurans
51 96128 1,2-Dibromo-3-chloropropane
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
92875
98077
100447
92524
117817
542881
75252
106990
156627
105602
133062
63252
75150
56235
463581
120809
133904
57749
7782505
79118
532274
108907
510156
67663
107302
126998
1319773
44
-------
Table 2-12. Initial List of 189 Hazardous Air Pollutants
Identified in the Clean Air Act Amendments of
1990 (28) (Continued)
Table 2-12. Initial List of 189 Hazardous Air Pollutants
Identified in the Clean Air Act Amendments of
1990 (28) (Continued)
No. CASa No.
Pollutant
No. CASa No.
Pollutant
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73 '
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
84742
106467
91941
111444
542756
62737
111422
121697
64675
119904
60117
119937
79447
68122
57147
131113
77781
534521
51285
121142
123911
122667
106898
106887
140885
100414
51796
75003
106934
107062
107211
151564
75218
96457
75343
50000
76448
118741
87683
77474
67721
822060
680319
100543 •
302012
7647010
7664393
123319
78591
58899
Dibutylphthalate
1 ,4-Dich!orobenze(p)
3,3-DichIorobenzidene
Dichloroethyl ether (Bis(2-
chloroethyl)ether)
1 ,3-Dichloropropene
Dichlorvos
Diethanolamine
N,N-Diethyl aniline (N,N-Dimethylaniline)
Diethyl sulfate
3,3-Dimethoxybenzidine
Dimethyl aminoazobenzene
3,3'-Dimethyl benzidine
Dimethyl carbamoyl chloride
Dimethyl formamide
1,1 -Dimethyl hydrazine
Dimethyl phthalate
Dimethyl sulfate
4,6-Dinitro-o-cresol, and salts
2,4-Dinitrophenol
2,4-Dinitrotoluene
1 ,4-Dioxane (1 ,4-Diethyleneoxide)
1 ,2-Diphenylhydrazine
Epichlorohydrin (1-Chloro-2,3-
epoxypropane)
1 ,2-Epoxybutane
Ethyl acrylate
Ethyl benzene
Ethyl carbamate (urethane)
Ethyl chloride (chloroelhane)
Ethylene dibromide (dibromoethane)
Ethylene dichloride (1,2-Dichloroethane)
Ethylene glycol
Ethylene imine (aziridine)
Ethylene oxide
Ethylene thiourea
Ethylidene chloride (1,'l-Dichloroethane)
Formaldehyde
Heptachlor
Hexachlorobenzene
Hexachlorobutadiene
Hexachlorocyclo-pentadiene
Hexachloroethane
Hexamethylene-1 ,6-diisocyanate
Hexamethylphosphoramide
Hexane
Hydrazine
Hydrochloric acid
Hydrogen fluoride (hydrofluoric acid)
Hydroquinone
Isophorone
Lindane (all isomers)
102 108316 Maleic anhydride
103 67561 Methanol
104 72435 Methoxychlor
105 74839 Methyl bromide (bromomethane)
106 74873 Methyl chloride (chloromethane)
107 71556 Methyl chloroform (1,1,1 -Trichloroethane)
108 78933 Methyl ethyl ketone (2-butanone)
109 60344 Methyl hydrazine
110 74884 Methyl iodide (iodbmethane)
111 108101 Methyl isobutyl ketone (hexone)
112 624839 Methyl isocyanate
113 80626 Methyl methacrylate
114 1634044 Methyl tert butyl ether
115 101144 4,4-Methylene bis (2-chIoroaniline)
116 75092 Methyl chloride (dichloromethane)
117 101688 Methylene diphenyl diisocyanate (MDI)
118 107779 4,4'-Methylenedianiline
119 91203 Naphthalene
120 98953 Nitrobenzene
121 92933 4-nitrobiphenyl
122 100027 4-nitrophenol
123 79469 2-nitropropane
124 684935 N-Nitroso-N-methylurea
125 62759 N-Nitrosodimethylamine
126 59892 N-Nitrosomorpholine
127 56382 . Parathion
128 82688 Pentachloronrtrobenzene (quintobenzene)
129 87865 Pentachlorophenol
130 108952 Phenol
131 106503 p-Phenylenediamine
132 75445 Phosgene
133 7803512 Phosphine
134 7723140 Phosphorus
135 85449 Phthalic anhydride
136 1336363 Polychlorinated biphenyls (aroclors)
137 1120714 1,3-Propane sultone
138 57578 beta-Propiolactone
139 123386 Propionaldehyde
140 114261 Propoxur (baygon)
141 78875 Propylene dichloride (1,2-
Dichloropropane)
142 75569 Propylene oxide
143 75558 1,2-PropyIenimine (2-methyl aziridine)
144 91225 Quinoline
145 106514 Quinone
146 100425 Styrene
147 96093 Styrene oxide
148 1746016 2,3,7,8-Tetrachloro-dibenzo-p-dioxin
149 79345 1,1,2,2-TetrachIoroethane
150 127184 Tetrachloroethylene (perchoroethylene)
151 7550450 Titanium tetrachloride
152 108883 Toluene
45
-------
Tabla 2-12. Initial List of 189 Hazardous Air Pollutants
Identified In the Clean Air Act Amendments of
1930 (28) (Continued)
Table 2-13. Hazardous Air Pollutants Found in Textile Plants (14)
Chemical CAS No. Potential Source(s)
No. CAS' No.
Pollutant
163 95807
154 584849
155 95534
156 8001352
157 120821
158 79005
159 79016
160 95954
161 88062
162 121448
163 1582098
164 540841
165 108054
166 593602
167 75014
168 75354
169 1330207
170 95476
171 108383
172 106423
173
174
175
176
177
178
179
180
181
183
184
185
186
187
188
189
2,4-Toluene diamine
2,4-Toluene dilsocyanate
o-Toluidine
Toxaphene (chlorinated camphene)
1 ,2,4-Trichlorobenzene
1 ,1 ,2-Trichloroethane
Trichloroethylene
2,4,5-Trichlorophenol
2,4,6-Trichlorophenol
Triethylamine
Trifluralin
2,2,4-Trimethyipentane
Vinyl acetate
Vinyl bromide
Vinyl chloride
Vinylidene chloride (1,1-Dichloroethylene)
Xylenes (isomers and mixture)
o-Xylenes
m-Xy!enes
p-Xyienes
Antimony compounds
Arsenic compounds (inorganic
arslne)
Beryllium compounds
Cadmium compounds
Chromium compounds
Cobalt compounds
Coke oven emissions
Cyanide compounds'5
Giyool ethers°182
Manganese compounds
Mercury compounds
Fine mineral fibers'1
Nickel compounds
Polycyclic organic matter6
including
Radionuclldes (including radon)'
Selenium compounds
* CAS s Chemical Abstract Service.
X'CN where X « H' or any other group where a formal dissociation
may occur. For example, KCN or Ca(CN)2.
0 Includes mono- and diethers or ethylene glycol, diethylene glycol,
and triethytene glycol R-(OCH2CH2)n-OR' where
n = 1,2, or 3
R « alkyl or aryl groups
R' m R, H, or groups that, when removed, yield glycol ethers with
the structure R-(OCH2CH)n-OR. Polymers are excluded from the
giycol category.
d Includes mineral fiber emissions from facilities manufacturing or
processing glass, rock, or slag fibers (or other mineral-derived fi-
bers) of average diameter 1 micrometer or less.
* Includes organic compounds with more than one benzene ring that
have a boiling point greater than or equal to 100°C.
1A type of atom that spontaneously undergoes radioactive decay.
Pollution prevention can be a viable low-cost alternative
for accomplishing air quality improvement. In addition to
Acetic acid
Ammonia
Chlorine
Ethylene oxide
Formaldehyde
64-19-7
7664-41-7
7782-50-5
75-21-8
50-00-0
Hydrochloric acid 7647-01-0
Methylene chloride 75-09-0
Perchloroethylene 127-18-4
Tetrachloroethane 79-34-5
Trichloroethylene 79-01-4
Toluene 108-88-3
Xylene 1330-20-7
Storage tank, dyeing
machines, dryers
Shop, storage tank
Shop, water treatment
Dryer stacks (wetting agents)
Bulk resin storage tanks,
dryers, curing ovens, finished
fabric warehouses
Dryer stacks (catalyst)
Shop, paint stripper, etc.
Dry cleaner, scour, carrier
Shop, inspection (spot remover)
Shop, inspection (spot remover)
Becks, dryers (carrier/scour)
Becks, dryers (carrier/scour)
being covered under Standard Industry Classification
(SIC) 22, Textiles, fabric coating operations (some of the
major HAP emitters) and surface finishers are tenta-
tively covered under Surface Coating Processes (27).
2.2.3.2 Air Pollutants
Only recently have reliable data been collected regard-
ing air toxics emissions from textile operations. As late
as 1990, most estimates of air emissions from manufac-
turing operations were calculated using mass balance
techniques rather than direct measurements (19). The
mass balance technique often is not reliable because of
the large quantities of input raw materials and output
products. Using the difference between large input and
output values to estimate the quantity of waste streams
can lead to uncertain results (29).
Early attempts during the 1980s to measure air pollut-
ants from textile operations were made using infrared
transmission analysis (25, 30). This method proved to
be a useful starting point, but it was unsatisfactory as a
primary means for quantifying air pollution. The original
Superfund Amendments and Reauthorization Act
(SARA) Title III inventories of the early to mid-1980s
also were a particularly poor source of air pollutant data.
In most cases, the data were inaccurate, and groups
with little knowledge of textile operations publicized the
lists, leading to publication of data that were seriously
flawed (26).
Several investigators have noted air pollutants that are
of concern in textiles, including volatile organic com-
pounds (VOCs), photoreactives (PRs), toxic air pollut-
ants (TAPs), and HAPs (11,25,31,32). As shown below,
most of these pollutants subsequently have been de-
46
-------
\ecled in air emission testing of textile operations. Since
the 1980s, direct reading tubes (DRAGER tubes) and
gas chromatographs/mass spectrographs (GCs/MSs)
have provided more reliable data (31, 33-35).
2.2.3.3 Sources
The main sources of air emissions in textile operations
are:
• Boilers
• Machine and equipment cleaning:
— General cleaners
- Specific implements and parts cleaners
- Screen-printing cleaners
• Processing machines:
- Ovens, for drying and curing
- Solvent processing units (e.g., dry cleaning)
- Dyeing machines
- Mix kitchens, drug rooms
- Warehousing for finished cloth and chemical drums
• Storage tanks (breathing losses)
• Wastewater treatment systems
In addition to boilers, high-temperature finishing, drying,
and condensation machines also emit many air pollut-
ants. Hydrocarbons are emitted from drying ovens and,
in particular, from mineral oil from high-temperature
(200°C) drying/curing (35). These processes can emit
formaldehyde, acids, softeners, and other volatile com-
pounds. Residues of fiber preparations and their oxida-
tion products sometimes form "blue haze" in heatsetting
processes. Carriers and solvents used in dyeing and
coating machines cause exhaust air pollution (36).
Textile manufacturing can produce oil and acid fumes
(especially from the tenter frame), plasticizers, and other
materials that can volatilize. Carbonizing of wool pro-
duces acids. Acetic acid emissions derive mostly from
storage tanks, especially from vents during filling, and
breathing losses (14, 36). The carbonizing process
emits sulfuric acid fumes and decating produces formic
acid fumes (37).
Dyeing and finishing operations can emit solvent va-
pors containing toxic compounds. These vapors might
include acetaldehyde, chlorofluorocarbons, p-dichlo-
robenzene, ethylacetate, chlorobenzene, hexane, sty-
rene, and others. Acetic acid and formaldehyde are two
major emissions of concern in textiles. Some process
chemicals exhaust into the fibers and are later evolved
from dryers as VOCs; these chemicals include methyl
naphthalene, chlorotoluene, trichlorobenzene, ortho-
dichlorobenzene, perchloroethylene, methyl ester or
cresotinic acid, butyl benzoate, and biphenyl (36). For-
maldehyde might be emitted from bulk resin storage tanks,
finished fabric warehouses, driers, and curing ovens.
Many types of cleaning and scouring operations are
used in textile operations, both batch and continuous.
Perchloroethylene is used for solvent scouring opera-
tions, and CFC-113, 1,1,1-trichloroethane, and trichlo-
roethylene are used to a lesser extent (38). These
materials also are used as solvents during application
of water-repellent finishes and for machine cleaning. In
the aggregate, cleaning and scouring chemicals were
estimated at 10,500 metric tons in 1988 (38).
Quality control (QC) inspectors in fabric and garment
manufacturing operations use solvent/air guns to re-
move spots that originate from sewing machines that
sling oil during high-speed seam sewing. The proper
pollution prevention strategy in such cases is to elimi-
nate the oil spots by modifying the sewing operation to
prevent oil slinging, which reduces the need for spotting
and cutting, as well as solvents, and also minimizes
labor requirements while improving quality.
Odors often are associated with oil or solvent vapors
and are usually removed by eliminating the source of the
odor. A common odor problem in textiles is carrier odors
from aqueous polyester dyeing and subsequent proc-
essing. Resin finishing also produces formaldehyde
odor. In addition, odor problems are associated with
sulfur dyeing on cotton and cotton blends, reducing or
stripping dyes with hydrosulfite, bonding, laminating,
back coating, and bleaching with chlorine dioxide (36).
Dust and fly are produced during processing of natural
fibers and synthetic staple, before and during spinning,
and by napping and carpet shearing. Most textile proc-
esses produce lint, which is not measured as a pollutant
but causes other difficulties (36). Lint can clog filters and
screens, causing them to malfunction. Lint can also foul
sensors in the air handling equipment and interfere with
incineration units. It collects in the ducts and stacks,
eventually becoming an extreme fire hazard.
2.2.3.4 Printing
In the past, printing operations used solvent-based print
pastes in which an oil-water emulsion provided the ap-
propriate rheology. These pastes have been replaced
almost completely by polymeric thickeners, which pro-
duce essentially no airborne pollutants. A few printers,
however, still use the oil-water emulsion systems as thick-
eners. A small number of specialty print shops also still
use solvent-based printing inks. A major source of sol-
vent emissions in screen printing operations is cleaning
of machines, screens, and squeegees, In one plant, GC
mass spectrometric analysis showed the presence of
the following VOCs (39):
• Trimethylcyclbhexane
47
-------
• Propylcyclohexane
• Hexylcyclohexane
• Ethylcyclohexane
• Methylethylcyclohexane
• Butylcyclohexane
• Decahydronaphthalene
• Bulylethylcyclopentane
• Methyldecane (three isomers)
• Xylene (three isomers)
• Ethylbenzene
• Trimethylbenzene (three isomers)
• Methylethylbenzene
• Other hydrocarbons
Urea is emitted from the curing of fiber reactive prints
and thermofix continuous dyeing of reactives. Much em-
phasis has been placed on eliminating urea from print
paste formulations because of problems with nitrogen
nutrients discharged in wastewater. (See Section
4.11.4.11 for a discussion of urea and printing.)
2.2.3.5 Pollution Prevention Procedures
Many practical pollution prevention methods are avail-
able to reduce toxic air emissions. These methods are
far-ranging and extend from optimization of boiler opera-
tion to redesign of products that produce fewer air toxics.
Traditional air pollution control methods relied on end-
of-stack add-on technologies to scrub or capture pollut-
ants in the air stream. These technologies often are
• capital-intensive and usually have high operating costs.
Pollution prevention methods often can achieve signifi-
cant reductions in pollution with little capital expense.
The main pollution prevention methods for reducing air
emissions are to:
• Design and manufacture products that do not pro-
duce HAPs.
• Identify sources and quantify emissions.
• Optimize boiler operations.
• Prescreen chemicals using material safety data
sheets (MSDSs).
• Prescreen fibers for volatile spin finish components.
• Trap bulk storage tanks.
• Minimize or eliminate chemical auxiliaries in aqueous
processes.
• Improve solvent processing operations.
• Avoid spills in bulk chemical off-loading areas.
• Investigate emerging technologies.
Design Products That Do Not Produce HAPs
Often, decisions made at the design stage significantly
affect the manufacturer's decision to use products that
contain VOCs, PRs, TAPs, and HAPs. These pollutants
result from the use of processing specialties required to
meet designer specifications. Usually, the designer has
no knowledge or expertise in the pollution conse-
quences of design decisions. The need to communicate
this information, as well as the specific nature of the air
issues involved, are reviewed in detail in other sections.
(See Sections 3.2.2.1 and 3.2.2.2 for product design and
Sections 1.2.1.1 through 1.2.1.5 and 2.2.3.1 through
2.2.3.5 for air pollutant issues.)
To summarize, the first step is to identify and communi-
cate problem areas, especially which colors, styles, and
fiber blends will produce air problems. Boiler emissions
are the main air pollutant from textile mills, so products
requiring low energy for production (and thus less steam
and electricity) are preferred because they produce less
air pollution. In addition, products with a high percentage
of right-first-time performance are generally better in all
pollution categories including air. Marketing decisions
can also strongly influence pollution. For example, short
runs, frequent style or color changeovers, and schedul-
ing are also important, as discussed in Chapter 6.
Some specific examples of design issues include:
• The tendency to use hydrocarbon softeners instead of
designing inherently soft fabrics. Softeners contain hy-
drocarbons that are emitted from drying ovens. In par-
ticular, mineral oil is emitted from high-temperature
drying/curing (35).
• Printing of fiber reactive dyes using urea, which is
emitted during the curing of fiber reactive prints and
thermofix continuous dyeing of reactives. Design al-
ternatives include the use of alternative colors (which
can be produced with colorants other than fiber re-
active) or adjustment of product fastness require-
ments to allow for pigment printing.
• The use of soil-release finishes (which are often sol-
vent-based finishes) as opposed to selecting inher-
ently soil-releasing fibers such as cotton.
• The use of water repellent finishes (which are often
solvent-based finishes) as opposed to selecting in-
herently water repellent soil-releasing fibers, such as
polyester or wool, and inherently water repellent fab-
ric constructions.
• The use of polyester and other fibers that contain
volatile spin finishes that volatilize during heatsetting,
as opposed to natural fibers that contain no spin
finish and do not require heatsetting. This eliminates
48
-------
not only the spin finish air pollution but also the burner
emissions required for the heatsetting oven.
Identify Sources and Quantify Emissions
Identifying sources and quantifying emissions are the
first steps in pollution prevention (40). Potential sources
can be identified by reviewing MSDSs for each chemical
in the facility (41). Once identified, potential sources can
be quantified by continuous emissions monitors and by
applying emission factors or preparing mass balance
calculations (40).
Point sources are the easiest to identify and monitor.
Fugitive or area sources are more difficult to identify and
quantify because of problems often encountered when
measuring flow rates and concentrations. Because of
the wide variety of sources and processes, the textile
industry has been described as one of the most difficult
in which to establish a good pollution prevention pro-
gram for air emissions (40).
Optimize Boiler Operations
Boilers are a main source of hazardous emissions, in-
cluding NOx and SOx. Improperly operated boilers can
contribute excess amounts of such pollutants. Careful
optimization of boiler operations is necessary to mini-
mize air emissions.
Prescreen Chemicals Using MSDSs
As described further in Sections 3.7, "Incoming Raw
Material Quality Control," and 3.12, "Raw Material Pre-
screening Before Use," best management practices for
pollution prevention include a comprehensive program
to prescreen all chemicals. Prescreening can start by
first consulting the MSDSs. For air emissions, shop
chemicals should receive special attention. Chemical
inventory managers should seek maintenance and proc-
ess chemicals that will not contribute to air emissions
(i.e., nonvolatile, nonhalogenated, and nonphotoreactive
chemicals and those not on the list of TAPs or HAPs).
Prescreen Fibers for Volatile Finishers
Incoming QC also can be performed on synthetic fibers
to identify spin finishes with components that could va-
porize during heatsetting. One method of prescreening
is to heat the fabric (or yarn) in a laboratory oven and
observe or sample the air from the oven vent. Sampling
can be performed using various methods described in
the literature (25, 30, 32, 34, 40).
Trap Bulk Storage Tanks
Storage tanks can be equipped with carbon canisters on
vents to remove fugitive vapors. The carbon canisters must
be maintained on a regular basis to effectively trap such
vapors. Filling systems also must be designed and main-
tained to prevent spills and vapor losses during operation.
Minimize or Eliminate Chemical Auxiliaries
Use of pressure dyeing at 250°F to 265°F for polyester
can eliminate the need for dye carriers. Mills should
seek to reduce the use of dyeing auxiliaries in general,
paying particular attention to those used for synthetics.
Alternative methods are shown in Table 2-14.
Table 2-14. Nonchemical Methods To Assist in Eliminating
Dyeing Auxiliaries
Dyeing Assistants Alternative Methods
Fiber Type
Acrylic
Nylon
Nylon
Polyester
Polyester/Cotton
To Target
Retarder
Retarder
Leveller
Carrier
Lubricant
of Control
Rate of temperature
rise
pH, temperature
pH, temperature
Temperature, time
Fabric transport
mechanism
A considerable amount of information on alternative
methods is included in Section 4.10, "Dyeing."
Improve Solvent Processing Operations
Solvents that pose hazards (PRs, HAPs, or TAPs) ide-
ally should be replaced with nonsolvent systems (i.e.,
aqueous or mechanical/physical). In cases where re-
placement is not possible, other procedures can be
undertaken:
• Review solvent selection to ensure use of the least
offensive, least volatile solvent. Nonhalogenated sol-
vents are generally preferable. Chlorinated solvents
can be substituted with deodorized kerosene, hex-
ane, or Stoddard solvent (38).
• Implement special practices for monitoring solvent
losses from textile operations (38, 40). Careful re-
cords should be maintained to accurately estimate
losses to the air. Solvent losses should be monitored
during special events in the process (e.g., startup,
shutdown, changeover).
• Dispense solvents directly from bulk container to ma-
chine; do not carry solvents in secondary containers.
Submerge fill pipes to avoid splashing, which in-
creases air/solvent contact (38).
• Purchase, or design and use, application-specific sol-
vent-use devices (e.g., for parts cleaning) (11).
• Plan and document routine maintenance for solvent-
use operations.
• Pay special attention to scheduling on solvent-use
processes to reduce start/stop/change losses.
• Reclaim and reuse solvents, either on site or off site. A
QC program for solvents is important because it helps
49
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detect decomposition of solvents during processing
or buildup of contaminants that can render the proc-
ess less effective or inhibit reclamation of the sol-
vents (38).
• Maximize capture efficiencies for solvent vapors from
processes (e.g., coated fabrics for offset printing
blankets) by proper design of containers, mix areas,
dryers, etc. In some cases, mills have spent more
than $1 million on reclamation equipment (e.g., carb-
on sorption, distillation) only to find that air pollution
is still a problem because of poor capture efficiencies.
• Focus on worker training to ensure proper handling of
materials, limiting their release to the atmosphere (38).
Train operators to look for leaks and potential spill points.
• Maintain solvent recovery equipment in top working
order. Batch distillation units generally range from as
low as 60 percent for inefficient units or difficult sol-
vents to 95 percent for efficient units (38).
Avoid Spills in Off-Loading Areas
Chemical spills frequently occur in off-loading areas.
Avoiding these fugitive sources of air pollutants is a
matter of proper procedures, work practices, worker
training, and facility design. Offloading areas should be
well lit and easily accessible with ample work space so
that the area remains orderly even when in full use. The
base or floor should be non-absorbent and should have
drainage and spill control features built in. One good
system often seen in bulk tank areas is gravel with an
underlying concrete drain system. Drains in off-loading
areas should flow to appropriate treatment or collection
areas, not to the storm sewer. If the area has a solid
floor, it should be smooth, well sealed, and have good
drainage (to avoid standing water or spilled liquids),
which facilitates cleanup. A vacuum should be available
for capturing powder spills, rather than washing them
down the drain with water from a hose.
Drums and bags of chemicals should not be stored in
standing water or over floor drains. Spill containment
pallets are available that help prevent small-scale spills
when off-loading drum chemicals. Bulk delivery hoses
should have automatic shutoff valves and should re-
ceive careful attention so that, in case of failure, the
delivery pump will shut down.
All receiving areas (bulk and warehouse) should be
clearly labeled because outside personnel (truck driv-
ers) may not be familiar with the area. Two people
should be present at all times during off-loading of
chemicals. Proper spill control equipment and training
are required. Deliveries should take place during day-
time hours so that proper procedures can be observed
and so that help will be available in case of an incident.
Used drums being returned should not be washed on
site, and residues should not be disposed of down the
drain. Direct returnable IBCs should be used instead. If
drums are used instead of IBCs, used drums should be
emptied or drained thoroughly into new drums.
Proper equipment and good preventative maintenance
in off-loading areas are essential, especially in bulk
storage areas. Use of automatic bulk chemical systems
helps control pollution, but the potential for large-scale
spills is significant, especially during off-loading.
Investigate Emerging Technologies
Technologies under examination for the future are su-
percritical fluid scouring and dyeing. These technologies
use high-pressure carbon dioxide as a solvent. When
the scouring or dyeing process is finished, no solvent
residues remain to be vaporized and no energy is
consumed in drying. Conventional disperse dyes on
polyester can be used. Off-the-shelf laboratory-scale
equipment already is available, and major equipment
manufacturers show some interesting products at the
International Textile Machinery exhibit each year.
2.2.4 Improving Treatability
Properly designed waste treatment systems can remove
or destroy many of the harmful contaminants in raw
textile wastewater and produce an effluent that can be
discharged safely to receiving waters. Certain wastes or
contaminants, however, can interfere with the ability of
treatment systems to operate to design specifications,
resulting in system upsets and exceedences of permit
limitations. Other contaminants are removed from the
treatment system and partition into sludges, disposal of
which can be difficult. Where possible, steps should be
taken to avoid these wastes or to improve their treata-
bility so that wastewater treatment systems can manage
them more easily.
Prominent among these wastes are the four types that are
amenable to pollution prevention (11, 42). These wastes,
and the treatment problems they may pose, include:
Waste Type
Problems
Hard-to-treat Pass through
Interfere with systems
Dispersible Hard to collect or capture for treatment
Offensive Inhibit treatment system operation
Produce hazardous sludges
High volume Increase loading
Cause shock loads if intermittent
The sections below describe treatment problems posed
by these wastes and recommend strategies for either
improving their treatability or reducing the amounts of
waste generated.
50
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Several characteristic problems that arise from the pres-
ence of hard-to-treat waste in textile waste treatment
systems include:
• Respiratory inhibition
• Bulking, poor settleability
• Sludge contamination
• Shock loading
• Pass-through of nondegradable materials
These effects can be quantified by several methods.
Moore suggested a system for treatability evaluation
(including inhibition), which includes results of Organi-
zation for Economic Cooperation and Development
(OECD) tests for biodegradability (301D), biomass im-
pact (209), and aquatic toxicity (202).4 Cooper reported
an alternate system in which chemicals are ranked on a
scale of 1 to 5 according to treatability using chemical
oxygen demand to biological oxygen demand
(COD:BOD) ratios (6).
Pollution prevention is a useful way to reduce treatment
problems arising from these wastes. Wood and Bishop
reported a highly successful pollution prevention pro-
gram at DuPont to reduce hydraulic load, organic load
(BOD), total suspended solids (TSS), methylene chlo-
ride; chloroform, and toluene (43). By reducing priority
pollutants at the source and eliminating shock loads,
wastes that interfered with treatment system operation
were reduced, with a corresponding reduction in the
incidence of permit violations (43). For more informa-
tion, see Section 2.1.2, "Hard to Treat Wastes," and
other sections mentioned below.
2.2.4.1 Respiratory Inhibition
Many types of materials inhibit the action of biological
waste treatment systems. The specific causes vary, but
the symptoms are generally the same: low specific oxy-
gen uptake and low BOD removal efficiency. The pollu-
tion prevention strategy is to seek out and control
materials that are toxic to the biomass. These include:
• Metals
• Chlorinated organics
• Biocides
Biocides comprise not only those mate rials used around
the wet processing plant but also preservatives (biocide
additives) in warp size materials. These can interfere
with the operation of the waste treatment system and
can inhibit aerobic stabilization of waslewater (2). Some
countries have banned use of chlorinated phenol
4 Moore, S., and Smith, B. 1994. Personal communication between
Samuel Moore, Burlington Research, and Bren't Smith, Department of
Textile Chemistry, North Carolina State University, Raleigh, NC.
biocides as a size additive (2). For more information, see
Section 4.7, "Slashing and Sizing."
2.2.4.2 Bulking and Poor Settleability
Some textile chemicals tend to form suspended solids
that neither settle nor float. These are usually neutral,
buoyant solids or materials with a large, hydrodynamic
radius and derive from specific sources, such as:
• Foam waste from coating, dyeing, and finishing.
• Acrylic sizes and handbuilders, which coagulate and
trap air.
• Print pastes based on acrylic materials as above.
• Resins, N-methylol film formers that coagulate with lint.
• Size materials, such as gums and synthetic sizes.
Many of these wastes result from printing, finishing, and
continuous dyeing. Methods of controlling them are
based primarily on reducing or eliminating discards.
This is described in Sections 4.11, "Printing," and 4.12,
"Finishing."
Undegraded size materials can cause biomass to ag-
gregate (flock) and inhibit oxygen transfer (2). Starch, in
some cases, causes growth of hard-to-settle filamen-
tous bacteria that interfere with the operation of clarifiers
(2). Polyvinyl alcohol (PVA) does not cause these prob-
lems, nor is it toxic. Polyacrylic acid (PAA) is hard to treat
and requires tertiary treatment (2).
2.2.4.3 Sludge Contamination
Occasionally, textile wastewater treatment sludges are
rendered hazardous because of accumulation of offen-
sive materials in the sludge. Some common causes are:
• Metals
• Surfactants
• Chlorinated organics
Modak lists several materials of concern that fall into the
above categories, such as chromium, copper, nickel,
zinc, isocyanates, heavy metals, chlorinated organics,
dioxins, mercury, cadmium, lead, pesticides (notably
pentachlorophenol from wool finishing), and adsorbable
organic halogens (AOX) (44). Richardson adds metals,
solvents, surfactants, and quaternary amines (quats) to
the list (21). Quats are used for processes such as
disinfecting, scouring and softening (21).
In some cases, these materials can be readily identified
from MSDS information (21). Special handling and use
procedures for such materials (e.g., special training) are
beneficial. Chemical substitutions should be investi-
gated and implemented where possible. For further in-
formation on pollution prevention strategies, see
51
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Sections 2.2.3, Toxic Air Emissions," 2.2.5, "Metals,"
and 2.2.6, "Aquatic Toxicity."
2.2.4.4 Shock Loading
Shock loadings occur when waste characteristics
change rapidly and upset waste system operations (21).
In textile batch operations, discharged processing
baths, cleaning chemicals, and excess chemical mix
disposal can create extreme short-term variations in
properties, as indicated in Table 2-15.
Table 2-15. Typical Short-Term Variations in Processing Bath
Parameters
Extremes
Property
High
Low
Temperature
pH
Salt
concentration
BOD
Rodox
221 0°F
11 +
120 g/L
100,000 ppm
Strongly oxidizing
75°F
3
Og/L
0 ppm
Strongly reducing
Equalization is required to eliminate these variations.
Even so, several pollution prevention approaches can
help. As discussed in several other sections, the use of
chemical equipment cleaners can be minimized by
proper process and equipment design, chemical selec-
tion, and scheduling. The need to dispose of obsolete
chemicals can be avoided by proper auditing, handling,
and prescreening protocol. Obsolete chemicals should
never be disposed of down the drain. Finally, process
alternatives can make the properties of processing
baths less extreme. If a bath or waste stream has ex-
treme properties, it may well have some direct reuse
value if segregated.
2.2.4.5 Pass-Through of Nondegradable Materials
Many materials discharged from textile operations are
not degradable in typical secondary activated sludge
waste treatment systems. These include:
• Salt (see Section 2.2.2, "Discharge of Electrolytes").
• Chloro-organics (see Sections 2.2.3, 'Toxic Air Emis-
sions," and 4.12, "Finishing").
• Solvents (see Sections 2.2.3, 'Toxic Air Emissions,"
and 4.12, "Finishing").
• Phosphates (see Section 3.5, "Chemical Alternatives").
• Color (see Sections 2.2.1, "Color Residues in Dyeing
Wastewater," 4.3, "Dyes," and 4.10, "Dyeing").
• Surfactants (see Sections 2.2.6, "Aquatic Toxicity,"
and 4.4, "Chemical Specialties").
• Nonsettling solids (see Section 2.2.4.3).
Pollution prevention approaches for these materials are
reviewed in other sections, as indicated. They originate
from a wide variety of sources in wet processing/Color
originates from print paste dumps, color kitchens,
screen and squeegee cleaning, dye bath, and continu-
ous dyeing mix discharges. Metals generally have the
same sources as color, plus print screen making, pho-
tograph laboratory processes, and contamination from
high-volume raw materials (e.g., salt, size). Solvents
derive from nonaqueous printing thickeners, machine
cleaning, screen cleaning, and shop uses. Nonsettling
solids come from coating, dyeing, finishing, print pastes
based on acrylic materials, warp size materials (e.g.,
gums and synthetic sizes), and foam from coating or
carpet printing (45).
2.2.5 Metals
The presence of metals in textile mill effluents is of
concern primarily because of their toxicity to aquatic and
mammalian species (8,11,21). Metals also inhibit waste
treatment operations and are difficult to remove or treat
using pollution control technologies (11, 21).
2.2.5.1 Sources
The sources of metals can be difficult to identify in
textile operations; locating metals sources requires
careful examination of all aspects of plant operations
(21). Among the possible sources are: incoming fiber,
water, dyes, plumbing, and chemical impurities. The
presence of metals in effluent is a worldwide concern
(44). All industries in Europe, including the textile
industry, are required to reduce 36 specific sub-
stances, including heavy metals such as chromium,
copper, nickel, and zinc by 50 percent or more. In
addition, 70-percent reductions of mercury, cadmium,
and lead are required (44). Many textile mills have
little or no metals in their effluent but, whenever met-
als are present, they often include those shown in
Table 2-16. The table indicates only harmful metals.
Materials such as iron are not listed.
Dyes
Some dyes include metals that are known to be toxic
such as copper (46). Metals can be present in dyes
for two different reasons. First, mercury or other met-
als are used as catalysts during the manufacture of
some dyes and can be present as a by-product (47).
Second, some dyes include metals as an integral part
of the dye molecule (47).
Dye manufacturers now are considering the environ-
mental impact of the dyes that they produce, in addition
to traditional concerns such as economy, higher wet
fastness, and high tinctorial value. Many anthraquinone
52
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Table 2-16. Typical Sources of Metals in Effluent
Metal Typical Sources
Arsenic
Cadmium
Chrome
Cobalt
Copper
Lead
Manganese
Mercury
Nickel
Silver
Tin
Titanium
Zinc
Fibers, incoming water, fugitive,
treated timber
Impurity in salt
Dyes, laboratory
Dyes
Dyes, incoming water, fiber
Dyes, plumbing, shop
Permanganate strip (repair mildew)
Dye/commodity chemical impurity
Dyes
Photo operations
Finishing chemicals, plumbing
Fiber
Dyes, impurity in commodity
chemicals, incoming water, plumbing
dyes are derived by sulfonation in the presence of mer-
cury catalysts. The mercury can cause pollution prob-
lems during the manufacture of the dye. Some dye
manufacturers (in Japan, for example) use mercury-free
manufacturing practices (48).
Dyes Based on Metals. For dyes that contain metals as
an integral part of the dye molecule, the metallic content
is essential to the dye's performance as a textile color-
ant. The metals most commonly found in dyes as part
of the dye structure are shown in Table 2-17 (8).
In addition to the dyes listed in Table 2-17, other types of
dyes can also contain metals, notably yellow pigments
based on lead chromate and orange pigments based on
molybdate (49). Also, some other pigments of various
colors are based on cadmium (49). Other studies (14, 45)
present lists of dyes and printing inks that contain metals.
The metal content of dyes easily can be determined by
consulting the MSDS for the dye or the Cl (11).
Table 2-17. Typical Metals Found in Dyes by Dye Class (8)
Dye Class
Typical Metals in Structure
Direct
Fiber Reactive
Vat
Disperse
Acid
Premets
Mordant
Copper
Copper and nickel
None
None
Copper, chrome, cobalt
Copper, chrome, cobalt
Chrome
' Does not imply that all dyes contain these metals.
The issue of "bound" versus "unbound" metal often is
raised regarding the metal content of dyes. Bound met-
als are those in which the metal is chelated with the dye
molecule, forming an integral structural element. More
specifically, the empty d-orbitals of the metal ions are
supplied with electrons donated from organic ligands
such as ethylene diamine triacetic acid (EDTA),
diethylene triamine penta acetic acid (DTPA), nitrilo
triacetic acid (NTA), or various substituents in the dye
molecule. An unbound metal is one that is not structur-
ally bound to the dye molecule but that simply exists in
some quantity in the dye formulation.
Dye companies often point out that bound metals exhibit
lower toxicity than free metals and that bound metals tend
to exhaust onto the substrate in dyeing so that they are not
discharged with the wastewater. Not all dye in the dye bath,
however, is exhausted (see Sections 2.2.1, "Color Resi-
dues in Dyeing Wastewater," and 4.3, "Dyes"). Further-
more, not all dye wastes come from the dyebath; dye
wastes also result from handling, weighing, small-scale
routine working losses, implement and drum cleaning, and
spills. Important factors to consider are that EDTA, DTPA,
NTA, and dye molecules are susceptible to biological deg-
radation and that secondary activated-sludge aerobic
treatment of the metal/ligand chelate produces free metals
(50, 51). As the chelate degrades in the waste treatment
system, metals are released as either precipitate in the
sludges or in pass-through that is discharged in wastewater
(50,51). Also, at this time EPA regulations do not recognize
any distinction between bound and unbound metals.
Dyes With Low-Level Metal Impurities. ADMI analyzed
1,298 dyes by x-ray fluorescence that do not contain
bound metal as an integral part of the dye molecule for
eight metals (arsenic, cadmium, chromium, cobalt, copper,
lead, mercury and zinc), as shown in Table 2-18. Specific
dyes within the various classes can contain significant
amounts of metals. The data do not include dyes that are
known to be metal-bearing as bound, integral parts of the
dye structure. The metals numbers in Table 2-18 are based
on casual metal in dyes (47). Table 2-19 lists specific dyes
having relatively high copper content (45). Note that these
data are somewhat dated but represent the only detailed
analysis of the metal content of dyes.
Dyeing Processes
Other sources of metals include the dyeing process.
Several sources in dyeing are not directly related to the
dyestuffs themselves, including afterchrome processes
for wool and clearing or discharge printing; copper after-
treatments for certain direct dyes, and impurities in fi-
bers, salt, caustic, and soda ash; as well as chemical
oxidizers and reducers.
Afterchrome processes for wool dyeing are discussed
below and also are discussed in Section 4.3, "Dyes," and
4.10, "Dyeing." Some mills may still use afterclearing or
53
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Tabla 2-18. Average Metal Concentration of Selected Dyes (47)
Number of Dyes Tested and Average Metal Concentration by Dye Type8
Metal
Acid
Basic
Direct
Disperse
Fiber
Reactive
Vat
Arsenic
Cadmium
413
417
137
137
313
313
177
177
46
1.4
46
58
58
Chromium
Cobalt
Copper
Lead
Mercury
Zinc
404
g
300
3.2
399
79
408
37
450
<1
421
<13
137
2.5
135
<1
136
33
135
6
132
0.5
122
32
303
3
271
<1
285
35
315
23
350
0.5
311
8
117
3
154
<1
153
45
161
37
196
<1
166
3
46
24
46
<1
46
71
46
52
46
0.5
46
4
58
83
58
<1
59
110
58
6
94
1
59
4
Top figure In each cell indicates the number of dyes tested; bottom figure indicates average metal concentration.
Tabla 2-19. Dyes With High Copper Content (45)
Dye Copper Content (%)
Bolamine F Red 3BL
Bolamine B Blue LT
Pyrazd F Violet MXD
Solantine Brown BRL
Atlantic Blue 8GLN-K
Atlantic Resinifast Blue 2R
SIrius Supra Turquoise LG
Supoflitefast Blue 2GLL
Direct Navy OFS
Belamtne Red 3BL
Solophenyl Brown BRL
FastoJito Blue L
Atlantic Black NR
4.00
3.68
3.00
3.00
2.70
2.50
2.29
1.00
0.70
4.00
3.00
2.70
1.50
discharge printing with zinc-stabilized reducing agents
(for disperse dyes on polyester). The technical literature
refers to these agents as "zinc sulfoxylate formalde-
hyde." These agents are discussed under oxidizing and
reducing agents below. Chemical oxidizers containing
manganese and chrome also are used in dyeing. In the
1960s, the use of dichromate was phased out (see
discussion of oxidizers below). Impurities (e.g., zinc,
mercury) in salt, caustic, and soda ash also can come
frofn dyeing processes. Fibers contain many types of
metals at low levels (52). Copper sulfate was discontin-
ued as an aftertreatment for direct dyes such as Cl
Direct Blue 98 at least 30 years ago, although some
authors still write about this topic.
Afterchrome Dyeing. A study group of the International
Wool Secretariat (IWS) identified four high-priority
areas, including the reduction of chromium in wool proc-
essing wastewater from chrome dyeing (53). Approxi-
mately 70 percent of wool dyeing currently uses heavy
metals, primarily chrome. Development of low-chrome
methods has been underway since 1976. Results of
these methods show reductions from approximately 155
ppm for conventional dyeing to levels of about 33 ppm,
8 ppm, and near 0 ppm for pH control, fresh bath, and
thiosulfate methods, respectively. The best solution
would be to develop black and navy dyes that do not
require chrome (53). These, however, are not currently
available.
Another development is azo dyes based on iron instead
of other more harmful metal ions such as cobalt, nickel,
chromium, nickel, lead, and zinc. Research already has
shown promise in substituting iron for cobalt in Acid Red
182 and Acid Blue 171 and substituting iron for chro-
mium in Acid Black 172. These new dyes are nonmu-
tagenic and do not introduce metals into dyeing
wastewater (4). Commercialization of these dyes is still
several years away, however.
54
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Plumbing
Metals can derive from plumbing, pumps, valves, and
other similar sources. Combining galvanized pipes with
brass fittings, valves, pump impellers, or other parts is
a common mistake, leading to galvanic reactions when
the pipes are exposed to acids, alkalis, or very high salt
concentrations found in textile processing solutions and
wastewater. These reactions liberate zfnc from the gal-
vanized surface.
Metals in a mill's influent raw water supply (notably copper
in city water) can exchange ions with solder joints in
plumbing, producing lead or tin effluent wastewater.
Residues can collect in wood, asphalt, soil, or old,
cracked or porous concrete sumps, pits, trenches,
drains, and treatment systems. These sorbed metals
can be released slowly over a period of months or even
years. This fugitive source of metals often defies easy
identification.
Chemicals
Sources of metals may also include chemicals used
in textile processing, as described in the following
paragraphs.
Oxidizing and Reducing Agents. During the 1940s and
1950s, the use of dichromate and permanganate as
oxidizers was common in textile mills, contributing to
high chromium levels in effluent. Zinc sulfpxylate formal-
dehyde reducing agents also were common. Zinc sul-
foxylate formaldehyde is used for afterclearing and for
discharge printing and stripping (i.e., repair work) (54).
During the last 30 years, however, most mills have
replaced these chemicals with the substitutions shown
in Table 2-20. ,
Finishes Containing Metals. Certain textile finishes con-
tain metals, including:
• Antifungal and odor-preventive finishes: Used for
socks and based on. organo-tin compounds.
Table 2-20. Replacements for Dichromate, Permanganate,
and Zinc Oxidizing Agents
Previous
Replaced With
Dichromate Peroxide
Periodate
Perborate
Air
Permanganate None, but the main necessity for
permanganate Was mildew removal
repair procedure, and mildew control
has improved with the advent of air-
conditioned warehouses. In other
words, the need has been eliminated.
Zinc-reducing agents Sodium hydrosulfite ("hydro")
• Water repellents: Based on chrome chloride stearic
acid adducts (55).
• Flame retardants: Based on either decabromobi-
phenyl oxide plus antimony oxide or titanium chloride
for wool (55).
From a pollution prevention point of view, controlling
releases of these metals in finishes is a matter of ensur-
ing appropriate handling practices, worker training, con-
trol of pad dumps and mix discards, auditing, and other
processes (14, 21).
Low-Level Metal Impurities in Commodities. Fibers
received in wet processing operations can contain
significant amounts of metals. Table 2-21 shows con-
centrations of calcium, magnesium, iron, copper, man-
ganase, and zinc brought to the bleaching stage in raw
cotton (52). These concentrations exceed the raw water
supply concentrations because of the leaching of metals'
from the cloth being processed. Table 2-22 shows the
results of testing two cotton samples for trace elements
(including metals). Natural fibers can absorb metals from
the environment. For example, raw cotton has been found
to contain metals at levels between 75 and 100 ppm, which
could translate to up to 10 ppm in wet processing effluent.
.Sources of metals include agricultural residues for natural
fibers (e.g., arsenic), polymerization catalysts and delus-
terants in synthetic fibers (e.g., copper, titanium), and im-
purities added to fibers (e.g., in warp size) (21). Low-level
metals are a significant problem. Salt, caustic, soda ash,
and other chemicals also contain trace amounts of zinc,
cadmium, and mercury.
Although the impurities in fibers and commodity chemi-
cals are present in ppm or smaller quantities, a large
operation can use, in the aggregate, several million
pounds per week of commodity raw materials. The net
Table 2-21. Contaminants in Processing Solutions in Textile
Mills: Peroxide Saturator Solutions From Three
Mills Bleaching Cotton Fabric in J Boxes8 (52)
Dissolved Metal in Processing Solution
(ppm)b
Metal
Calcium
Magnesium
Iron
Copper
Manganese '
Zinc
Average of 14
Samples0
68
24
1.5
0.25
0.03
0.49
Range
Lowest
28
7.7
0.5
0.065
0.01
0.14
Highest
130
49
3
0.68
0.06
0.8
a H2O2; 35% 15 to 30 g/L; sodium silicate, 42 Be., 15 to 39 g/L
b As metal. Tests performed by Industrial Testing Laboratories, Inc.,
2350 Seventh Boulevard, St. Louis, MO 63104.
G From four trials each in two mills and six trials in one mill.
55
-------
Table 2-22, Trace Element Analysis of Cotton After
Preparation (51 )a
Element
Titanium
Iodine
Manganese
Magnesium
Copper
Vanadium
Chlorine
Aluminium
Mercury
Samarium
Uranium
Lanthanum
Cadmium
Gold
Arsenic
Antimony
Bromine
Sodium
Potassium
Cerium
Calcium
Selenium
Thorium
Chromium
Europium
Ytterbium
Barium
Cesium
Silver
Nickel
Scandium
Rubidium
Iron
Zinc
Cobalt
Molybdenum
Sample 1 (ppm)
2.11 ± 5%
0.140 ± 7%
1.632 ±0.5%
7.24 ±15%
2.29 ± 8%
0.070 ± 10%
24.156 ± 5%
33.91 ± 1%
<0.010
<0.005
<0.001
<0.4
<0.8
<0.0001
<0.2
<0.05
1.081 ±1%
<500.0
<500.0
<0.2
<100.0
<0.1
<0.004
0.095 ± 7%
<0.001
<0.03
<5.0
0.0076 ±10%
<0.005
<5.0
0.0038 ± 2%
<20.0
68.29 ±10%
7.38
0.017
<1.0
* Neutron activation analysis of trace elements
effect is to
wastewater.
Raw Water.
Sample II (ppm)
<0.5
0.0104 + 7%
1.741 ±0.5%
9.80 ±15%
3.16 + 8%
0.032 ±10%
21 .32 ±5%
29.45 ±1%
<0.010
<0.005
<0.001
<0.4
<0.8
<0.0001
<0.2
<0.06
0.131 ±5%
<500.0
<500.0
<0.2
<100.0
<0.1
<0.004
0.142 ± 3%
<0.001
<0.03
<5.0
0.0083 ±10%
<0.005
<5.0
0.0038 ± 2%
<30.0
60.04 ±10%
7.35
0.024
<1.0
in cotton fabric.
generate significant amounts of metals in
Metals often are found in
incoming water,
reported in Smith (4) in the southeastern United States,
however, showed levels below 0.1 ppm for each of these
(see Table 2-23). Copper is added to public water sys-
tems to control algae growth in tanks and ponds. Alumi-
num, in the form of alum, is another commonly added
material. These metals can undergo ion exchange with
plumbing (especially lead solder joints), valves, and
pump parts to produce lead or other less electromag-
netive metals in the mill's effluent.
2.2.5.2 Pollution Prevention Strategies
Procedures to reduce or eliminate metals must start with
identification of metals and their sources and follow with
an analysis of metals levels to determine the relative
importance of that metal pollution. Identification can be
made either by analysis of effluent or examination of
input chemicals and process requirements, such as
water. General pollution prevention methods of reducing
or eliminating metals include:
• Careful prescreening of all chemicals (see Section
3.12, "Raw Material Prescreening Before Use").
• Substituting for metal-containing compounds (e.g.,
with nonmetal dyes).
• Improving efficiency of the process or operations by
lowering chemical use while maintaining product
quality objectives, perhaps by means of automation.
Another method is to improve management of opera-
tions (e.g., better chemical handling skills).
• Elimination of galvanized plumbing.
Table 2-23. Raw Water Quality in Textile Mills in Southeastern
United States (52)a
Concentration of Constituents
(ppm)
Range
Constituent Equivalency of 10 Lowest Highest
Calcium CaCO3 12.9 1 46.5
Magnesium CaCOa 3.8 1.5 7.8'
Sodium CaCO3 36 5.7 76.1
Alkalinity
Bicarbonate CaCO3 27.7 10 110
Carbonate CaCOa 1.4 0 10
pH — 7.2 5.7 7.8
Iron Fe2* 0.1 0.01 0.31
Copper Cu2+ 0.02 0.01 0.1
Manganese Mn2+ 0.01 0 0.05
Zinc Zn2+ 0.11 0 0.24
as city drinking water supplies can often contain more
than 1 ppm of zinc, copper, and/or iron (21). Tests
a Tests performed by Industrial Testing Laboratories, Inc., 2350 Sev-
enth Boulevard, St Louis, MO 63104.
56
-------
As metals analysis has improved over the years and
detection limits have decreased, regulatory limits on
metals have also been lowered. Regulatory authorities
may now set metals limits for some mills in the low ppb
range. For example, a small textile operation discharg-
ing 50,000 gallons of wastewater per day with a 3-ppb
limit on a particular metal discharges less than 200
milligrams of metal per day.
Dyes without metals should be used wherever possible.
If a shade cannot be matched with a metal-free color (as
is often the case with bright green and royal blue direct
and fiber reactive colors), reducing the metal-bearing
dye content is often possible by substituting part of the
dye. In the case of green shades, brighter blues and
greens contain metals. In the example shown below, a
blue/yellow/red match of a green shade could be substi-
tuted with a lower metal version by replacing the red with
a duller, but non-metal-bearing blue. This substitution
could carry the necessary dullness in the shade and at
the same time reduce the amount of rnetal-bearing bril-
liant blue in the recipe:
Table 2-24. Non-Copper-Containing Direct and Fiber Reactive
Dyes
Best Match Recipe
1.4 percent
2.0 percent
0.1 percent
Metal-bearing blue
Yellow
Red for shading
Alternative Reduced-Metal Match
0.5 percent Metal-bearing blue
0.8 percent Non-metal-bearing blue
1.7 percent Yellow
No red shading color because nonmetallic blue is duller
As a good pollution prevention practice, a mill should
always insist on knowing the Cl designation of all dyes
used, in addition to their pollution status, including metal
content. This issue is important because some of the
major dye companies have withdrawn support for the Cl
system.
Pollution prevention strategies for dealing with metal-
containing dyes are to:
• Seek substitutes (for all or part of the metal-contain-
ing dye) that do not contain metal (14, 45). Table 2-24
provides a good selection of fiber reactive dyes that
do not contain metal as a component of the dye
structure (8).
• Ensure maximum fixation by optimizing the process (45).
• Provide special auditing, handling, and worker train-
ing where these dyes are used. Special handling and
use procedures for metal-bearing materials (e.g.,
segregating waste streams with separate plumbing
Yellow 50
Yellow 106
Orange 37
Red 76
Red 80
Red 153
Blue 75
Blue 98
Blue 106
systems) are necessary in some cases to keep met-
als out of the wastewater and to reduce aquatic tox-
icity (21).
Using disperse dyes that can be aftercleared with caus-
tic (alkali) only eliminates the need for reducing agents
(e.g., hydro), which can contribute BOD and, in some
cases, metals to the effluent (48).
2.2.6 Aquatic Toxicity
Compounds that contribute to aquatic toxicity are a
particular environmental concern for all industry. The
national policy prohibiting discharge of toxic pollutants
is embodied in Section 101(a)(3) of the federal Clean
Water Act. EPA has identified toxic compounds under
the general heading "Priority Pollutants," numbering ap-
proximately 126 compounds in 65 classes (see Table
2-25). Categorical discharge standards regulate these
compounds. EPA identified priority pollutants on the ba-
sis of their known or suspected carcinogenicity, mu-
tagenicity, teratogenicity, or high acute toxicity (56).
2.2.6.1 Aquatic Toxicity of Textile Wastewater
The aquatic toxicity of textile industry wastewater varies
considerably among production facilities. Data are avail-
able that show that some facilities have fairly high
aquatic toxicity, while others show little or no toxicity.
Table 2-26 summarizes the results for about 75 mills in
North Carolina.5 Of the mills tested, effluent from about
one-half showed no toxicity. The median value of all
positive tests was 48.5 percent, indicating that a 48.5-
percent solution of the mill's treated effluent caused
50-percent mortality among tested organisms.
2.2.6.2 Testing for and Determining Toxicity
Numerous compounds in textile effluent can contrib-
ute to aquatic toxicity, including dyes, dyeing auxilia-
ries, and surfactants. Identifying all the toxic compounds
used in textile production is impossible because of
the huge variety of chemicals used and the lack of
data on their toxicities. Several methods may be used,
however, to identify compounds of concern. Knowledge
of the chemical compounds used by a mill and their
associated toxicities (or classes of toxicity) can help
5 Tedder, S.W. 1986. Aquatic bioassay toxicological summary (memo-
randum). North Carolina Division of Environmental Management,
Raleigh, NC (March 31).
57
-------
Table 2-25. List of EPA Priority Pollutants3
Coda CASb No. Pollutant
P058
P038
P101
P034
P027
P002
P010
POOS
P042
P086
P007
P065
P019
P111
P107
P108
P109
P018
P066
P009
P078
POOS
P031
P035
P037
P051
P110
P085
P084
P071
P116
P129
P079
P083
P074
P039
P076
P089
P102
P103
P105
P093
P092
P073
P059
P060
P106
P082
P033
100027
100414
1024573
105679
106467
107028
107062
107131
108602
108883
108907
108952
110758
11096825
11097691
11104282
11141165
111444
117817
118741
120127
120821
120832
121142
122667
124481
12672296
127184
129000
131113
1332214
1746016
191242
193395
205992
206440
218019
309002
319846
319857
319868
3547044
50293
50328
51285
534521
53469219
53703
542756
4-nitrophenol
Ethylbenzene
Heptachior epoxide
2,4-Dimethylphenoi
1 ,4-Dichlorobenzene
Acrolein
1 ,2-Dichloroethane
Acrylonitrile
Bis(2-chloroisopropyl) ether
Toluene
Chlorobenzene
Phenol
2-chloroethyl vinyl ether (mixed)
PCB-1260 (aroclor 1260)
PCB-1254 (aroclor 1254)
PCB-1221 (aroclor 1221)
PCB-1232 (aroclor 1232)
Bis(2-chloroethyl)ether
Bis(2-ethylhexyl)phthalate
Hexachlorobenzene
Anthracene
1 ,2,4-Trichlorobenzene '
2,4-Dichlorophenol
2,4-Dinitrotoluene
1 ,2-Diphenylhydrazine
Chlorodibromomethane
PCB-1248 (aroclor 1248)
Tetrachloroethylene
Pyrene
Dimethyl phthalate
Asbestos (fibrous)
2,3,7,8-Tetrachlorodibenzo-P-dioxin
(TCDD)
1 ,1 ,2-Benzoperylene
(benzo(ghi)perylene)
lndeno(1 ,2,3-cd)pyrene
(2,3-o-phenylenepyrene)
3,4-Benzofluoranthene
(benzo(b)fluoranthene)
Ruoranthene
Chrysene
Aldrin
Alpha-BHC
Beta-BHC
Delta-BHC
4,4'-DDE (p-p'-DDX) -
4,4'-DDT
Benzo(a)pyrene (3,4-Benzopyrene)
2.4-Dinitrophenol
4,6-Dinitro-o-cresoI
PCB-1242 (aroclor 1242) '
1 ,2,5,6-Dibenzanthracene
(dibenzo(a,h)anthracene)
1 ,3-Dichloropropylene
(1 ,3-Dichloropropene)
Table 2-25. List of EPA Priority Pollutants3 (Continued)
Code CASb No. Pollutant
P017 542881 Bis(chloromethyl)ether (deleted)
P006 56235 Carbon tetrachloride
(tetrachloromethane)
P072 56553 1,2-Benzanthracene
(benzo(o)anthracene)
P121 57125 Cyanide (total)
P091 57749 Chlordane (technical mixtures and
metabolites)
P104 58899 Gamma-BHC (lindane)
P022 59507 Parachlorometacresol
P090 60571 Dieldrin
P036 606202 2,6-Dinitrotoluene
P063 621647 N-nitrosodi-n-propylamine
P061 62759 N-nitrosodimethylamine
P023 67663 Chloroform (trichloromethane)
P012 67721 Hexachloroethane
P004 71432 Benzene
P011 71556 1,1,1 -Trichloroethane
P098 72208 Endrin
P094 72548 4,4'-DDD (p,p'-TDE)
P122 7439921 Lead (total)
P123 7439976 Mercury (total)
P124 7440020 Nickel total)
P126 7440224 Silver (total)
P127 7440280 Thallium (total)
P114 7440360 Antimony (total)
P115 7440382 Arsenic (total)
P117 7440417 Beryllium (total)
P118 7440439 . Cadmium (total)
P119 7440473 Chromium (total)
P120 7440508 Copper (total)
P128 7440666 Zinc (total)
P046 74839 Methyl bromide (bromomethane)
P045 74873 Methyl chloride (chloromethane)
P.016 75003 Chloroethane
P088 75014 Vinyl chloride (chloroethylene)
P044 75092 Methylene chloride (dichloromethane)
P047 75252 Bromoform (tribromomethane)
P048 75274 Dichlorobromomethane
P013 75343 1,1-Dichloroethane
P029 75354 1,1-Dichloroethylene
P050 75434 Dichlorofluoromethane (deleted)
P049 75694 Trichlorofluoromethane (deleted)
PI 00 76448 Heptachlor
P053 77474 Hexachlorocyclopentadiene
P125 7782492 Selenium (total)
P054 78591 Isophorone
P032 78875 1,2-Dichloropropane
P014 79005 1,1,2-Trichloroethane
P087 79016 Trichloroethylene
P015 79345 1,1,2,2-Tetrachloroethane
P113 8001352 Toxaphene
P070 84662 Diethyl phthalate
P068 84742 Di-n-butyl phthalate
58
-------
Table 2-25. List of EPA Priority Pollutants" (Continued)
Code CASbNo. Pollutant
Table 2-26. Results From Aquatic Toxicity Testing of Effluent
From 75 Textile Mills3-"
P081
P067
P062
P080
P052
P064
P021
P057
P055
P020
P028
POOS
P025
P024
P056
P030
P069
P096
P097
P112
P026
P095
P001
P041
P075
P040
P043
P077
P099
85018
85687
86306
86737
87683
87865
88062
88755
91203
91587
91941
92875
95501
95578
98953
NA°
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Phenanthrene
Butyl benzyl phthalate
N-nitrosodiphenylamine
Ruorene
Hexachlorobutadiene
Pentachlorophenol
2,4,6-Trichlorophenol
2-nitrophenol
Naphthalene
2-chloronaphthalene
3,3-Dichlorobenzidine
Benzidine
1 ,2-Dichlorobenzene
2-chlorophenol
Nitrobenzene
1 ,2-Trans-dichloroethylene
Di-n-octyl phthalcite
Beta-endosulfan
Endosulfan sulfale
PCB-1016(aroclor1016)
1 ,3-Dichlorobenzene
Alpha-endosulfan
Acenaphthene
4-bromophenyl phenyl ether
1 ,2-Benzofluoranthene
(benzo(b)fluoranthene)
4-chlorophenyl phenyl ether
Bis(2-chloroethoxy) methane
Acenaphthylene
Endrin aldehyde
Toxicity (%)
Number of Tests in
That Range
a46 CFR 2264 (January 1981).
CAS = Chemical Abstract Service.
0 NA = not applicable.
predictwhetheraneffluenttoxicityproblem exists. One
source of information is MSDSs, which list chemical
ingredients, their known toxic effects, and other charac-
teristics. Other sources include manufacturer formula-
tions if they are listed or can be provided by the
manufacturer. Analysis of these compounds or of the
effluent to determine their precise chemical nature (in-
cluding toxicity) is, practically speaking, impossible.
Another approach for assessing toxicity is to measure
whole effluent toxicity (chronic or acute), without regard
to the specific chemical compound(s) that contributes to
toxicity. The textile industry produces many thousands
of compounds in effluent, and identifying and testing all
of them is impractical. As a result, toxicity testing of the
whole effluent stream on aquatic organisms is a cost-ef-
fective means of determining overall toxicity. Toxicity
testing proceeds by exposing freshwater, estuarine, and
marine life forms in tanks to either stationary, renewed,
or flowing effluent. Species tested include algae, shrimp,
silversides, and minnows. Toxicity is calculated in vari-
<9
10-19
20-29
30-39
40-49
50-59
60-69
70-79
80-89
90-100
>100 (no toxicity)
7
6
8
2
4
9
3
8
2
3
38
Toxicity in the table is LCso in percent; thus, higher numbers repre-
sent lower toxicity.
See footnote 2.
ous ways: measuring death rates, observing birth de-
fects, and noting other biological indications. One com-
mon measure of toxicity is LD50, which stands for lethal
dose 50 percent, meaning the amount of chemical dose
required to cause mortality in 50 percent of the test
population. LC50 (lethal concentration 50 percent), an-
other common measure, represents the concentration
of effluent in the dilution water that causes mortality in
50 percent of the test population (56).
2.2.6.3 Types of Toxic Chemical Compounds
The sources of aquatic toxicity in textile wastewater can
be hard to identity (21). Despite the lack of knowledge
concerning the exact composition or toxicity of many
textile dyes and auxiliary chemicals, many generally
known groups of chemical agents contribute to aquatic
toxicity of textile wastewater. These agents include (21):
• Salt
• Surfactants
• Metals
• Toxic organic chemicals
• Biocides
• Toxic anions
Examples of compounds in each of these classes and
their sources are shown in Table 2-27. Information re-
lated to the toxicity of these compounds and pollution
prevention strategies effective for each are discussed in
the following paragraphs. In addition, each category is
also discussed in other chapters of this document.
These sections provide further details concerning
59
-------
Table 2-27. Typical Causes of Aquatic Toxicity
Agent Chemical Example Typical Source
Salt NaCI, Na2SO4 Dyeing
Surfactants Ethoxylated phenols Multiple sources
Metals Copper, zinc, etc. Dyes
Organfcs Chlorinated solvents Scour, machine
cleaning
Biockies Pentachlorophenol Wool fiber contaminant
Toxic anlons Sulfide ' Sulfur dyeing
amounts, sources, and appropriate pollution prevention
practices.
Dyes
Most textile dyes have low aquatic toxicity. A study of 46
commercially important dyes, summarized in Table 2-28,
showed that 29 (60 percent) had very low aquatic toxic-
ity of (LCgo greater than 180 ppm) (57). The toxicity
distribution of the dyes is shown in Table 2-29.6 The
numbers indicate that, for example, 7 of the 46 dyes exhib-
ited toxicity at concentrations of between 1 and 10 ppm.
For the few dyes that exhibit higher toxicity charac-
teristics, it is important to realize the degree of dilution
that normally occurs.
• Atypical batch (exhaust) dyebath using 1 percent dye
owg at 10:1 bath ratio contains 1,000 ppm of dye.
• If the dye is 90 percent exhausted onto the fabric,
the concentration would drop to 100 ppm in the spent
dyebath.
• When combined with other process wastewater from
processes such as preparation, or washing off, the
concentration drops to about 5 ppm. (Note: assumes
millwide water consumption of 20 gallons per pound
of fabric at 8.34 pounds per gallon.)
• Assuming that the in-stream concentration/dilution
factor for the textile wastewater is 10 percent in the
receiving stream (a fairly severe assumption), the
In-stream concentration" would be less than 1 ppm.
This assumes that none of the color is removed in
treatment and that the toxicity of the degradation
products is equal to that of the original dye.
If the spent dyebath is combined, however, with cleanup
waste, spilled dye, and discarded mixes, the in-stream
value could be higher.
As a class, certain types of dyes exhibit higher toxicity
than others. Table 2-30 shows the toxicity of the 47 dyes
6 Note that this study used purified dyes. Typical commercial dyes
contain 20 to 80 percent other materials; thus, toxicities of in-use
dves should be 20 to 80 oercent below those reoorted for the pure
Table 2-28.
C.I.
Number
10338
11855
14645
15510
15711
18965
19555
20170
20470
21010
22610
24401
24890
24895
25135
26360
28160
29025
29160
20145 (or
30145)
30235
31600
40000
40622
42000
42535
47020
48055
51005
53185
53630
59105
59825
61505
61570
62055
62500
63010
67300
69015
69500
69825
74180
NAa
NA
NA
Effect of 46 Selected
Minnow, Pimephales
Tests (57)
Dye
Disperse Yellow 42
Disperse Yellow 3
Mordant Black 11
Acid Orange 7
Acid Black 52
Acid Yellow 17
Direct Yellow 28
Acid Orange 24
Acid Black 1
Basic Brown 4
Direct Blue 6
Direct Blue 218
Direct Yellow 4
Direct Yellow 12
Acid Yellow 38
Acid Blue 113
Direct Red 81
Direct Yellow 50
Direct Red 23
Direct Brown 95
Direct Black 38
Direct Black 80
Direct Yellow 11
Fluorescent
Brightening Agent 28
Basic Green 4
Basic Violet 1
Disperse Yellow. 54
Basic Yellow 11
Bssic B|UG 3
Sulfur Black 1
Vat Blue 43
Vat Orange 1
Vat Green 1
Disperse Blue 3
Acid Green 25
Acid Blue 25
Disperse Blue 7
Acid Blue 45
Vat Yellow 2
Vat Brown 3
Vat Green 3
Vat Blue 6
Direct Blue 86
Acid Yellow 151
Disperse Red 60
Direct Yellow 106
Dyes on the
Promelas, in
96 Hour
(mg/L)
>180
>180
6
165
7
>180
>180
130
>180
5.6
>180
>180
>180
125
23
4
>180
>180
>180
>180
>180
>180
>180
>180
0.12
0.047
>180
3.2
4
>180
>180
>180
>180
1
6.2
12
52
>180
>180
>180
>180
>180
>180
29
>180
>180
Fathead
Static Bioassay
Temperature
(°C)
15
15
15
17
15
17
15
17
15
20
17
17
15
15
15
15
17
17
17
17
17
17
17
17
18
15
15
18
15
15
15
15
15
15
18
15
15
15
15
15
15
15
17
15
15
17
substances.
a NA = not available.
60
-------
Table 2-29. Frequency Distribution of Toxiclty Test Results
for 46 Commercial Dyes (57)
Table 2-30. Toxicities of Various Dye Classes (57)
Toxicity Range
(LC50 ppm)
>180 '..
100-180'
10-100
1-10
0.1-1
<0.1
Totals
Number of
Dyes in Range
29
3
4
7
2
1
46
Percent of
Total
63.0
6.5
8.7
15.2
4.3
2.2
100.0
by dye class. Cationic materials generally are very toxic.
Fortunately, cationic dyes exhaust essentially 100 per-
cent in batch dyeing operations (see also Section 4.3,
"Dyes"). At the time of this study, the fiber reactive dyes
that are now popular were not in widespread use. These
would exhibit similar toxicity to acid and direct dyes
except that they are typically accompanied in wastewa-
ter by large amounts of salt.
From the above, pollution prevention strategies can be
directly deduced, including:
• Selecting nontoxic dyes if information is available.
• Using minimum amounts of dye.
• Using dyes of high tinctorial value.
• Ensuring maximum exhaustion of the dyebath by
proper dyeing" process, pH, salt, etc. (see Sections
2.2.1, "Color Residues in Dyeing Wastewater," and
4.3, "Dyes").
• Selecting treatable dyes that degrade to nontoxic
products. Unfortunately, data on these dyes are not
readily available to dyers.
• Maintaining proper processes such as special han-
dling, worker training, recordkeeping for dyes of high
toxicity (e.g., basic dyes).
Surfactants
Surfactants and related compounds (detergents, emul-
sifiers, dispersants) are used in almost every textile
process and can be an important contributor to effluent
toxicity (and BOD). The wide variety of available alter-
natives allows for selection of less-polluting chemicals.
Quaternary amines used for processes such as disin-
fecting, scouring, softening are particularly toxic and
should be avoided wherever possible (21). These are
reviewed in detail in Section 4.4, "Chemical Specialties."
Surfactants are important in a large number of textile
processes, including:
• Lubricating
Dye Class
Disperse
Acid
Mordant3
Direct
Basic
Brightener
Sulfur
Vat
Fiber reactive
Number
Tested
6
12
1
14
5
1
1
7
0
Number
Toxic
2
8
1
1
5
0
0
0
0
Percent Found
To Be Toxic
33.3
66.7
100.0
7.1
100.0
0.0
0.0
0.0
—
a Mordant is an obsolete class similar to acid dyes.
• Spin finishing
• Desizing
• Scouring
• Mercerizing
• Bleaching
• Wet finishing
• Foam finishing
• Dyeing
• Foam dyeing
Most textile surfactants are either nonionic or anionic.
Nonionic surfactants dissolve in water without forming
ions, while anionic surfactants form negative ions when
dissolved in water. The major classes of each are:
• Nonionic surfactants:
— Alcohol ethoxylates
- Alkylphenol ethoxylates
• Anionic surfactants:
— Alkylbenzene sulfonates
— Alcohol ethoxysulfates
Surfactants are a major contributor to the aquatic toxicity
of textile effluent and foaming. Nonionic surfactants of
the type used in textile processing can be acutely toxic
to aquatic life at levels as low as 1 ppm and can produce
chronic effects in the 0.1 to 1.0 ppm range (58). Surfac-
tants in raw textile waste have been found in concentra-
tions ranging from 50 to 200 ppm (58). The concentration
in treated effluent depends on the degree of biodegra-
dation of the surfactant in the treatment plant. The choice
of surfactant determines the degree of degradation and
the ultimate concentration in discharged effluent. Linear
alcohol ethoxylate (LAEs), linear alkylbenzene sulfon-
ates, and alcohol ethoxysulfates are more biodegrad-
able than APs (58-60) and thereby produce less foaming
61
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in receiving waters. These are discussed in detail in
Section 4.4, "Chemical Specialties."
Salt. Salts of various types are used as raw materials or
are produced as by-products of other textile wet proc-
esses (e.g., neutralization). Several authors have iden-
tified the large amounts of salt used in textile dyeing,
particularly in conjunction with fiber reactive dyes, as a
significant future problem area for the textile industry (8).
Typical cotton batch dyeing operations use quantities of
salt that range from 20 percent to 80 percent owg, and
the usual salt concentration in such wastewater is 2,000
to 3,000 ppm (11). Federal guidelines for in-stream salt
concentrations have been established at 230 ppm (21).
The treatment of mixed wastewater to reduce salt to
levels that meet such limits is extremely difficult and
expensive by any known method. Pollution prevention
is the only reasonable alternative to solve the dilemma
presented by this hard-to-treat, toxic, and high-volume
waste. General methods of dealing with salt are dis-
cussed in Section 2.2.2, "Discharge of Electrolytes." In
addition, two specific methods for reducing salt require-
ments (pad-batch dyeing and dyebath reuse) are re-
viewed in detail in Section 4.10, "Dyeing."
Toxic Organic Chemicals. Textile effluents may contain
numerous types of toxic organic compounds, both vola-
tile and nonvolatile. In the 1980s, the state of North
Carolina studied toxic materials (excluding surfactants)
in wastewater from five textile wet processing mills that
had shown aquatic toxicity in the past (61)7 Results
from these tests, shown in Table 2-31, identified be-
tween 8 and 42 toxic organic compounds.
Most of the identified materials were hydrocarbons. Sev-
eral chlorinated organic solvents were detected, includ-
ing perchioroethylene, trichlorobenzene, methylene
chloride, and chloroform. Many esters were also de-
tected, primarily benzoates, phthalates, and esters of
hexanedioic acid. Other compounds identified included
acetone, cyciohexanone, cyclohexanol, and other alco-
hols, such as 2-ethyl hexanol, and acids, such as
hexadecanoic acid.
Halogenated organics, particularly organochlorines, are
produced as a by-product of wool shrinkproofing proc-
esses. These chemicals are of concern when they later
appear in receiving water or drinking water supplies as
AOX. The chlorine/Hercosett process of shrink proofing
wool with chlorine generates 39 milligrams AOX per liter
of liquid discharged (53). This is far higher than the
proposed United Kingdom standard of 1 milligram per
liter (53).
The aquatic toxicities of numerous organics found in
textile wastewater in the five-mill study are shown in
Table 2-31. Toxic Organics Detected in Wastewater From
Five Textile Wet Processing Mills (61)
Number of Toxic Organic Chemicals Identified
Site
Volatiles
Nonvolatiles
Total
1
2
3
4
5
34
12
0
4
4
8
2
11
4
5
42
14
11
8
9
Table 2-32 (61). Of the approximately 50 compounds
identified, aquatic toxicity data were readily available for
only 11. This points to a basic problem in preventing
aquatic toxicity: the lack of data on aquatic toxicity of
chemical compounds. Also, in many cases, the chemical
constitution of specialty chemical processing assistants
is unknown to the user. Methods of addressing this
problem are described in Section 4.4, "Chemical Spe-
cialties."
Biocides. Biocides are used for two major purposes in
textiles: 1) to prevent biological growth during textile
processing, and 2) as a finish to impart biocidal proper-
ties to textile products.
Biocides for in-process textile use include:
• Weed killers used around bulk storage tanks and
buildings.
• Disinfectants for restrooms.
• Algae suppressants in air-cooling tower systems.
• Mildew inhibitors as a component of warp size.
• Biocides applied to sheep, a source of contaminants
in wool.
• Defoliants and insecticides applied to cotton in farming.
Table 2-32. Aquatic Toxicities of Organic Chemicals Found in
Effluent From Five Textile Mills (61)
Chemical
Aquatic Toxicity Range (ppm)
See footnote 2.
Acetone
Chloroform
Cyclohexane
Cyclopentane
Decahydronaphthalene
Ethyl benzene
Methylene chloride
Perchioroethylene
Trichlorobenzene
Xylene
>1,000
10-100 (animal carcinogen)
10-100
>1,000
100-1,000
10-100
100-1,000
10-100 (animal carcinogen)
0-10
10-100
62
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These may end up in effluent, sanitary wastewater, or
stormwater discharges (runoff) from the industrial facility.
Several biocidal finishes are also applied to textile ma-
terials, including:
• Insecticides for carpets
• Mothproofing agents for wool
• Odor suppressants for socks/hosiery
The simplest, cheapest method of applying these com-
pounds to wool products is through dyebath addition.
Unfortunately, the biocides, such as permethrin, do not
exhaust fully onto the fabric and consequently are dis-
charged with the effluent.
Several European countries are now requiring textile
operations to reduce discharges of specific pesticide
materials, notably pentachlorophenol (PCP) for wool
finishing and AOX (44). PCP and its salts and esters are
used as industrial biocides to prevent deterioration of
wood and cellulosic fibers. PCPs have been used in
carpet manufacture, but their presence is not limited to
wool carpets. Carpet backing materials, particularly jute,
polypropylene, and latex, also contain PCP, often at
levels greater than those found in wool fibers (62). PCP
use on textile products has been criticized, and its use
for indoor materials is banned in Germany, Sweden,
Switzerland, Japan, and the United States (62).
In the United Kingdom, mothproofing of wool and wool
blend carpets was previously performed using chlor-
phenylid-based agents; these have since been banned.
Other mothproofing agents in use include permethrin
and cyfluthrin. Permethrin is effective and has low tox-
icity to humans but high aquatic toxicity (63). Quantities
of all three mothproofing agents are found in British
rivers and current practices are not expected to comply
with environmental quality standards (EiQS) established
in the United Kingdom (53). The discharge of leftover
portions of processing baths is the main source of the
problem (63). This is one of the four high-priority areas
identified by the IWS study group (53).
Substitutes for permethrin and cyfluthrin are thus being
sought. Diphenylurea and cyfluthrin can replace per-
methrin. Diphenylurea may exhibit less aquatic toxicity
but, in some cases, is less biodegradable. A synthetic
pyrethroid alternative to permethrin, cycloprothrin, ex-
hibits good performance and has aquatic toxicity three
orders of magnitude less than permethrin. Nippon
Kayaku manufactures cycloprothrin and markets it as
Cyclosal. The toxic properties are very low. The mam-
malian toxicity LD50 in rats and mice is greater than
5,000 milligrams per kilogram, and no irritant, carcino-
genic, teratogenic, or mutagenic properties have been
observed (64).
Pesticide Residues. Residues of pesticides used to pre-
vent parasitic infestation on sheep may be present in
effluent from wool scouring operations.- At one time,
many organochlorine pesticides were in widespread
use, but many countries have banned these pesticides
because of concerns over mammalian toxicity. Some
countries still use organochlorine pesticides such as
lindane (gamma-hexachlorocyclohexane), campheclor
(ortoxaphene), and dieldrin. Organophosphate and syn-
thetic pyrethroids are more commonly used today. Both
of these groups have lower mammalian toxicity and are
less persistent in the environment than organochlorine
pesticides, although they may still contribute to effluent
toxicity.
The degradability of various chemical pesticides in
wastewater treatment plants has been assessed in stud-
ies by Mickelson et al. (1). Dieldrin was degraded by 81
percent, dichlorofenthion by 79 percent, diazinon by 87
percent, cyperethrin-1 by 84 percent, cyperethrin-2 by
90 percent, and deltamethrin by 92 percent. These are
discussed further in Section 4.12.4.
Toxic Anions. The main source of toxic anions, in textile
operations is sulfide from sulfur dyeing. Sulfides are
very odiferous and toxic, and can be a significant prob-
lem in wastewater from sulfur dyeing.
When initially introduced in the late 1800s, sulfur dyes
were reduced in the dyehouse by boiling the dye with
soda ash and sodium sulfide to render them soluble
(12). A by-product was foul-smelling sulfur dioxide. .A
later advance was the introduction in 1936 of prere-
duced/presolubilized sulfur dyes, which eliminated the
need for onsite reduction processes. In the 1990s, new
types of sulfur dyes have been introduced that feature
lower sulfide content, thus producing less sulfide in the
effluent and fewer hydrogen sulfide odors in the mill and
in the waste treatment system. The chemical nature of
the proprietary reducer is not revealed, but it appears to
be an organosulfur reducing agent (12).
One strategy for reducing sulfide in wastewater is to
substitute glucose for sulfide-containing reducing
agents (44). Even cheaper reducing sugars from corn
can reportedly perform the same function. In one case,
the sulfide concentration was reduced from 30 ppm to 2
ppm in the effluent. A small increase in BOD resulted,
which was easily handled in the treatment system,
whereas the sulfide waste was not amenable to waste
treatment. The zone settling velocities of the clarifiers
improved as a result of the decrease in sulfide, thus
increasing waste treatment efficiency. In addition, odors
decreased substantially.
The change to glucose did not increase operating costs.
Estimated cost savings were $20,000 per year from
avoided costs' for sulfide removal equipment, and a
savings of $30,000 per year in waste treatment opera-
63
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tton costs. The corn sugars were a waste stream from
the corn starch industry, and the corn starch manufac-
turer saved $12,000 in waste treatment system expan-
sion and $2,400 in operating expenses (44).
Other Toxic Compounds. Other potential sources of tox-
icity in wastewater may be present in textile operations:
• Evidence shows that some dyes and other com-
pounds have the potential to degrade from relatively
safe forms into toxic compounds. For example, the
dye FD&C Food Red #5, although not a textile dye,
degrades into products that are both carcinogenic
and mutagenic (46).
• Sequestering agents such as EDTA and DTPA form
stable complexes with heavy metals. These com-
plexes can pass right through a treatment plant and
into receiving waters, where the compounds eventu-
ally break down, releasing the metals into the envi-
ronment (50, 51).
• Phosphonates and polyphosphates can be used as
dispersing agents as well as complexing agents. Both
compounds have a low bioeliminability and have
been banned in several countries because of eutro-
phication problems (50, 51).
• Four high-priority areas in wool finishing identified
by the IWS study group are: 1) pesticide residues
in wastewater from wool contaminated with pesti-
cides, 2) discharge of mothproofing agents from
wool carpet manufacture, 3) halo-organic com-
pounds from wool shrinkproofing, and 4) chromium
from chrome dyeing (53).
Pollution Prevention Strategies
Pollution prevention strategies for toxic chemical com-
pounds include:
• Special handling and use procedures for the com-
pounds described above may be necessary to keep
them out of the wastewater. Strategies include em-
ployee training to improve awareness of the toxicity
potential of priority compounds and improve their
handling, separate plumbing to segregate these
wastes and facilitate special treatment and screening
procedures to identify ingredients and evaluate their
potential contribution to toxicity before being put in use.
• Chlorinated solvents should be replaced with non-
chlorinated types (21).
• Rapid, large pH variation can also produce aquatic
toxicity and should be avoided (21).
• MSDSs are a good, but often limited, source of infor-
mation. MSDS data focus on human exposure and
toxicity, which may correlate with environmental ef-
fects. Some specific chemical types, however, may
have low human toxicity but high aquatic toxicity
(e.g., quaternary amines). Other prescreening tech-
niques are discussed in Section 3.12, "Raw Material
Prescreening (Before Use)."
• Products, colors, and finishes that require the use of
toxic production chemicals should be identified to the
designer and to the consumer, and alternatives that
can be produced more safely should be promoted.
Many producers and consumers of textile products
are aware of environmental concerns and factor in-
formation about environmental impacts into their pur-
chasing decisions.
• Nonprocess chemicals, such as those used for clean-
ing, maintenance, and weed killing should receive
special attention in terms of prescreening evaluation
(see Section 3.12, "Raw Material Prescreening (Be-
fore Use)"), employee training (see Section 5.3,
'Training Programs and Worker Attitudes"), as well
as storage and handling in general (see Sections 3.8,
"Maintenance, Cleaning, and Nonprocess Chemical
Control," and 4.18, "Support Work Areas").
• Ultraviolet disinfection is a good replacement for
biocides in cooling water towers.
2.2.7 Water Conservation
Water is used extensively throughout textile processing
operations. Almost all dyes, specialty chemicals, and
finishing chemicals are applied to textile substrates from
water baths. In addition, most fabric preparation steps,
including desizing, scouring, bleaching, and merceriz-
ing, use aqueous systems.
The amount of water used varies widely in the industry,
depending on the specific processes operated at the
mill, the equipment used, and the prevailing manage-
ment philosophy concerning water use. Reducing water
consumption in textile processing is important for fur-
thering pollution prevention efforts, in part because ex-
cess water use dilutes pollutants and adds to effluent load.
Mills that currently use excessive quantities of water can
achieve large gains from pollution prevention. A reduc-
tion in water use of 10 to 30 percent can be accom-
plished by taking fairly simple measures. A walkthrough
audit can uncover water waste in the form of:
• Hoses left running.
• Broken or missing valves.
• Excessive water use in washing operations.
• Leaks from pipes, joints, valves, and pumps.
• Cooling water or wash boxes left running when ma-
chinery is shut down.
• Defective toilets and water coolers.
64
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In addition, many less obvious causes of water waste
exist. These causes are presented below by subcate-
gory, unit process, and machine type.
2.2.7.1 Water Consumption in Textiles
Subcategory
Textile operations vary greatly in water consumption.
Table 2-33 summarizes the water consumption of vari-
ous types of operations (14). Wool and felted fabrics
processes are more water intensive than other process-
ing subcategories such as wovens, knits, stock, and
carpet.
Water use can vary widely between similar operations
as well. For example, knit mills average 10 gallons of
water per pound of production, yet water use ranges
from a low of 2.5 gallons to a high of 45.2 gallons. These
data serve as a good benchmark in determining whether
water use in a particular mill is excessive.
By Unit Process
Water consumption varies greatly among unit proc-
esses, as indicated by Table 2-34. Certain dyeing proc-
esses and print afterwashing are among the more
intensive unit processes. Within the dyeing category,
certain unit processes are particularly low in water con-
sumption (e.g., pad-batch). Low water-consuming dye-
ing alternatives are discussed in depth in Section 4.10,
"Dyeing."
Table 2-34. Water Consumption by Unft Process (3, 11, 46,
65, 66)
WWJ WWJ
Process
Yarn and fabric forming
Slashing
Preparation:
Singeing
Desizing
Scouring
Continuous bleaching
Mercerizing
Dyeing:
Beam
Beck
Jet
Jig
Paddle
Skein
Stock
Pad-batch
Package
Continuous
Indigo range
Printing
Print afterwashing
Finishing:
Chemical
Mechanical
Water
Consumption
Nil
0.06 to 0.94
Klil
Nil
0.3 to 2.4
2.3 to 5.1
0.3 to 14.9
0.12
20
28
24
12
35
30
20
2
22
20
1 to 6
3
13.2
0.6
Nil
Reference
66
8,66
66
66
8
11
46
46
46
11
11
11
65
46
46
66
8
8
8
By Machine Type
Different types of processing machinery use different
amounts of water, particularly in relation to the bath ratio
in dyeing processes (the ratio of the mass of water in an
exhaust dyebath to the mass of fabric). Washing fabric
consumes greater quantities of water than dyeing.
Water consumption of a batch processing machine de-
pends on its bath ratio and also on mechanical factors,
Table 2-33. Water Use in Textile Processing (14)
Water Use
(gallons per pound of production)
Processing
Subcategory
Wool
Woven
Knit
Carpet
Stock/Yarn
Nonwoven
Felted fabric
Minimum
13.3
0.6
2.4
1.0
0.4
0.3
4.0
Median
34.1
13.6
10.0
5.6
12.0
4.8
25.5
Maximum
78.9
60.9
45.2
19.5
66.9
9.9
111.8
such as agitation, mixing, bath and fabric turnover rate
(called contact), turbulence and other mechanical con-
siderations, as well as physical flow characteristics in-
volved in washing operations. These factors all affect
washing efficiency.
In general, heating of dyebaths constitutes the major
portion of energy consumed in dyeing. Therefore, low-
bath-ratio dyeing equipment not only conserves water
but also saves energy, in addition to reducing steam use
and air pollution from boilers. Low-bath-ratio dyeing ma-
chines conserve chemicals as well as water and also
achieve higher fixation efficiency. But the washing effi-
ciency of some types of low-bath-ratio dyeing machines,
such as jigs, is inherently poor; therefore, a correlation
between bath ratio and total water use is not always exact.
2.2.7.2 Types of Wastewater
Many sources of different types of wastewater can be
found in textile operations. The most common categori-
zation scheme for wastewater is:
65
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Category
Example
Noncontact
Storm
Cleanup
Process wasta
Condensata
Cooling
Parking lot and roof drains
Machines, facility, filter backwash
Prepare, dye, finish, water-jet loom
Boiler traps, blowdown
Each type of wastewater offers different possibilities for
conservation, recycle, and reuse.
Noncontact Cooling Water
Noncontact cooling water typically is isolated from all
processes and, therefore, remains essentially pure af-
ter use. Cooling water includes water from water-
cooled bearings and heat exchangers in dyeing
machines, cooling cans on continuous ranges, and
cooling towers for power boilers. In general, cooling
water can be recycled directly back into the clear well
or other process water supply reservoir. Most mills use
excessive amounts of cooling water; therefore, this
area presents significant conservation possibilities. In
particular, water-cooled bearings require only a small
amount of water to operate properly. A relatively simple
solution Is to regulate the water with flow restrictors,
although this is rarely done. Another excessive use of
water Is cooling water left running when machines are
shut down. Finding cooling water, as well as washbox
water, running on dye ranges that have been shut down
for months or even years is not unusual.
Stormwater
Stormwater from parking lot and roof drains always
should be handled in a separate discharge that is prop-
erly permitted and monitored. Stormwater sometimes is
improperly connected to the process wastewater treat-
ment system, resulting in additional load. An examina-
tion of the correlation between rainfall and treatment
system influent can detect an improper connection.
Stormwater should be audited on a regular basis to
detect and address problems as they occur. Stormwater
originating off site should not be allowed to run onto mill
property and mix with onsite Stormwater, resulting in
external causes for Stormwater permit violations.
Cleanup Water
Cleanup water derives from machine maintenance and
cleaning, filter backwash, facility cleaning, and other
activities. The dirty water generally collects in floor
drains because mills often clean the shop floors by
washing them down with water, which runs into floor
drains. Because of this practice, floor drains should
never be plumbed into the Stormwater system. Instead,
floor drains should lead directly to the process wastewa-
ter treatment system. The practice of using water to
wash down the floors and letting water run into floor
drains also should be eliminated from all mill proce-
dures. Spills and other cleanup activities should be done
with wet/dry shopvac vacuum cleaners wherever possi-
ble. To minimize spills, chemical handling procedures
should be implemented. In particular, automated chemi-
cals dispensing, weighing, and handling systems are
useful (see Section 4.18, "Support Work Areas").
If water is used for machine and facility cleaning, it should
be provided through low-volume, high-velocity nozzles,
which clean more efficiently with less water. All hoses
should be equipped with automatic shutoffs so that the
flow automatically stops whenever the hose is not being
used. A single running hose can waste 5,000 to 8,000
gallons per day. Plants often have 5 or 10 of these hoses
running at different locations. Often, the shutoff valves on
hoses are broken, inconveniently located, or nonexistent.
Wherever possible, cleanup water should be obtained
from washwater waste, not from the freshwater supply.
Process Water
Wastewater from processing is the most common
source of environmental concerns for textile operations.
The main unit processes that produce waste are wash-
ing operations. These operations are found in almost all
areas of preparation and dyeing. The details of water
conservation in washing operations are discussed below.
Washing and rinsing operations are two of the most
common operations in textile manufacturing that have
significant potential for pollution prevention. Many proc-
esses involve washing and rinsing stages, and optimi-
zation of washing processes can conserve significant
amounts of water. In some cases, careful auditing and
implementation of controls can achieve wastewater re-
ductions of up to 70 percent (67). The washing and rinsing
stages of preparation typically require more water than
the preparation stages (e.g., bleaching, dyeing) (67). Sev-
eral typical washing and rinsing processes include:
• Drop and fill batch washing.
• Overflow batch washing.
Table 2-35. Water Consumption for a Typical Bleach Range (68)
Water Consumption
Stage (gallons per hour) Percent
Saturators
Steamer and J boxes
Washers
Desize
Scour
Bleach
Dry cans
Total
550
150
3,700
3,100
3,100
450
11,050
5.0
1.4
0.0
33.5
28.1
28.1
4.1
100.0
66
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• Continuous washing (countercurrent, horizontal, or
inclined washers).
A report on water consumption for a typical continuous
bleach range found that consumption was more than
11,000 gallons per hour or 0.27 million gallons per day
(see Table 2-35). Washing stages accounted for 9,900
gallons per hour, or 90 percent of the total. The application
of the following simple, low-technology methods of
water conservation reduced water use (68):
• Properly regulate flows: 300 gallons per hour sav-
ings.
• Counterflow bleach to scour: 3,000 gallons per hour
. savings.
• Counterflow scour to desize: 3,000 gallons per hour
savings.
The total water savings without process modification
was 0.15 million gallons per day, or 55 percent of water
use. A process modification such as a combined one-
stage bleach and scour also would save 6,200 gallons
of water per hour, or an additional 0.15 million gallons
per day, along with energy savings (68).
Drop-Fill Versus Overflow
In the drop/fill method of batch washing, spent washwa-
ter is drained and the machine is refilled with a fresh
wash bath. The fabric or other substrate in the machine
retains much of the previous bath, perhaps up to 350
percent owg. This percentage can be reduced by me-
chanical means (e.g., extraction, blowdown) (67). Com-
parison of several methods of washing after bleaching
shows the benefits of countercurrent wash methods
(see Table 2-36). Methods 5 and 6, which implement
countercurrent washing, produce savings of 26 and 53
percent compared with the standard drop/fill method.
These results are based on comparisons of washing
processes that would produce the same degree of re-
duction of fabric impurities using computer models.
Countercurrent washing processes require the addition
of holding tanks and pumps (67). The capital cost of
setting up such a reuse system is low (69). Typically, the
following installation costs can be expected for a system
capable of recycling 75,000 gallons per day:
Table 2-36. Water Use in Batch Washing (67)
Process Description
Wash/Rinse Water Use
(Bath Ratio) (gal/Ib)
Percent
Change
From
Standard
System
Pump
Tank
Piping
Electrical
Total
Cost
$3,000
$14,000
$5,000
$1,000
$23,000
1 Standard—three-step 1:8 1.62 —
drop/fill
2 Reduced bath—seven- 1:5 1.26 -22.2
step drop/fill ,
3 Continuous overflow 1:8 2.38 446.9
4 Continuous overflow— 1:5 1.49 -8.0
reduced bath
5 Three-step drop/nil, 1:8 1.19 -26.5
reuse bath 2
6 Three-step drop/fill, 1:8 0.75 -53.7
reuse bath 2 and 3
Typical savings from such an installation are $95,000
per year. In many cases, reducing wastewater also re-
duces the need for expensive waste treatment systems.
Brenner et al. (67) present a computer analysis that
assumes complete knowledge of the state of washing
systems at any given time (i.e., the amount of contami-
nant remaining in the fabric). In the real world, time
constraints and the ability to accurately control such
processes are issues. For example, in the drop/fill
method, counting the number of drops and fills is rela-
tively simple. This method facilitates matching of actual
mill production processes with the computer-predicted
results above.
On the other hand, controlling overflow washing is more
difficult. Optimum control of overflow washing would
require a knowledge of the amount of contaminant left
in the substrate. In practice, this level of monitoring and
control is not possible, and as a result, flow and time
control are inadequate. Therefore, the overflow washing
method almost always uses more water than predicted
above because of a lack of control. Further information
about the water-saving features of drop/fill versus over-
flow can be found in Brenner et al. (67), Smith (14), and
Wagner (8).
2.2.7.3 Washwater Reuse
Many strategies can be applied for reusing washwater.
Three of the most common strategies are countercur-
rent washing, reducing carryover, and reusing washwa-
ter for cleaning purposes.
Countercurrent Washing
The countercurrent washing method is relatively
straightforward and inexpensive to implement in multi-
stage washing processes. Basically, the least contami-
67
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Fabric
Entr
Fabric .
Exit
Vertical Configuration
Fabric
Exit
Fabric
Entry
Horizontal Configuration
Figure 2-4. Vertical and horizontal washer configurations (11).
nated water from the final wash is reused for the next-
to-last wash and so on until the water reaches the first
wash stage, after which it is discharged. This technique
is useful for washing after continuous dyeing, printing,
desizing, scouring, or bleaching.
An important variant of the countercurrent principle is
"horizontal" or "inclined" washers, as shown in Figure
2-4 (11). Horizontal or inclined washing is more efficient
because of the inherent countercurrent nature of water
flow within the process. The mechanical construction of
an inclined or horizontal countercurrent washer has to
be much better than c traditional vertical washer, how-
ever. Sloppy roll settings, weak or undersized rolls, un-
evenness, bends, bows, biases, bearing play, or other
misalignments within the machine are much more im-
portant in a horizontal or inclined washer because the
weight of water pressing down on the fabric can cause
it to sag, balloon, or stretch. If properly constructed and
maintained, horizontal or inclined washers can produce
high-quality fabrics with much better washing efficiency
and reduced water use.
Low Carryover
Because the purpose of washing is to reduce the
amount of impurities in the substrate, as much water as
possible must be removed between sequential washing
steps in multistage washing operations. Water (contain-
ing contaminants) that is not removed is "carried over"
into the next step, contributing to washing inefficiency.
Proper draining in batch drop/fill washing and proper
extraction between steps in the continuous washing
process are important. Often, 350 percent owg is carried
over in typical drop/fill procedures (67). This amount can
be reduced in some batch machines (e.g., yarn package
dyeing, stock dyeing) by using compressed air or
vacuum blowdown between washing steps.
In continuous washing operations, squeeze rolls or vac-
uum extractors typically extract water between steps.
Equipment employing vacuum technology to reduce
dragout and carryover of chemical solutions with cloth,
stock, or yarn is used to increase washing efficiency in
multistage washing operations. These devices are de-
scribed in Section 3.19, "Pollution Prevention Through
New Equipment."
In one case history, a processor installed vacuum slots
after each wash box in an existing multistage continuous
washing line and was able to reduce the number of
boxes from eight to three (70). Wash boxes with built-in
vacuum extractors are available for purchase, as well as
washers for prints that combine successive spray and
vacuum slots without any bath for the fabric to pass
through. Because the fabric is never submerged, bleed-
ing, marking off, and staining of grounds is minimized,
and water use decreases (70). Another washer configu-
ration with internal recycling capabilities is the vertical
counterflow washer, which sprays recirculated water
onto the fabric and uses rollers to squeeze waste
through the fabric into a sump, where it is filtered and
recirculated. The filter is unique, consisting of continu-
ous loops of polyester fabric that rotate continuously and
are cleaned of filtrate at one end with a spray of clean
water. This construction allows for maximum removal of
suspended solids from water before discharge or reuse
in another process. High-efficiency washing with low
water use results. Energy use decreases greatly be-
cause less water must be heated.
Reuse for Cleaning Purposes
In many types of operations, washwater can be reused
for cleaning purposes. In printing, cleanup activities can
be performed with used washwater, including (71):
• Backgray blanket washing
• Screen and squeegee cleaning
• Color shop cleanup
• Equipment and facility cleaning
A typical preparation department may also reuse wash-
water as follows (71):
• Reuse scour rinses for desizing
• Reuse mercerizer washwater for scouring
68
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• Reuse bleach washwater for scouring
• Reuse water-jet loom washwater for desizing
• Recycle kier drains to saturator
2.2.7.4 Water Conservation
Work Practices
Workers can greatly influence water use. Sloppy chemi-
cal handling and poor housekeeping can result in exces-
sive cleanup. Poor scheduling and mix planning also
can require excessive cleanup and lead to unnecessary
cleaning of equipment such as machines and mix tanks.
Leaks and spills should be reported and repaired
promptly. Equipment maintenance, especially mainte-
nance of washing equipment, is essential.
Inappropriate work practices waste significant amounts
of water; good procedures and training are important.
When operations are controlled manually, an operations
audit checklist is helpful for operator reference, training,
and retraining.
In one case history, a knitting mill experienced excessive
water use on beck dyeing machines (20). A study of
operating practices revealed that each operator was
filling the machines to a different level,, Some operators
filled the becks to a depth of 16 inches, others as much
as 24 inches. Also, the amount of water used for wash-
ing varied. Some operators used an overflow procedure,
and others used drop/fill or "half baths" (repeatedly
draining half of the bath, then refilling it). Inspection of
the written procedures showed that the fill step simply
said "fill." The wash step simply said "wash." Without
training and without a specific operating procedure, op-
erators were left to determine water use on their own.
This case may seem extreme, but even the best mills,
which have well-documented production procedures,
often do not have documented cleaning procedures.
Cleaning operations that contribute large amounts of
pollution to the total waste stream include machine
cleaning, screen and squeegee cleaning, and drum
washing.
Engineering Controls
Several areas of engineering control have been dis-
cussed, but a few additional areas deserve mention.
Every mill should have moveable water meters that can
be installed on individual machines to document water
use and evaluate improvements. In practice, mills rarely
measure water use but rely on manufacturers' claims
concerning equipment and water use. The manufactur-
ers' estimates are useful starting points for evaluating
water consumption, but the actual performance of
equipment depends on the chemical system used and
the substrate. Therefore, water use is situation-specific
and should be measured on site for accurate resufts.
The water meters should be regularly maintained and
calibrated.
Other important engineering controls, some of which
have been discussed in other sections of this chapter,
include:
• Flow control on washers.
• Flow control on cooling water (use minimum necessary).
• Cpuntercurrent washing.
• High extraction to reduce dragout.
• Recycle and reuse.
• Detection and repair of leaks.
• Detection and repair of defective toilets and water
coolers.
Machinery should be inspected and improved where
possible to facilitate cleaning and to reduce susceptibil-
ity to fouling. Bath ratios sometimes can be reduced by
using displacers that result in lower chemical require-
ments for pH control as well as lower water use. An
example is shown in Figure 2-5.
Process Changes
Several process changes are worth mentioning in terms
of water conservation. These changes are briefly noted
here and covered in more detail in Sections 4.10, "Dye-
ing," and 4.9, "Preparation":
• Pad-batch dyeing
Fabric Exit
Dye
Reduces Volume
but Gives Long
Path in Dye
Liquor
Liquor
Fabric
Path
Pad
Trough
Guide Rollers
Figure 2-5. Pad with displacer.
69
-------
• Processing bath reuse
• Water recycle in preparation
Pad-Batch Dyeing. Three major problems that face cot-
ton dyers are water-use reduction and elimination of
color and salt from dye wastewater. Fiber reactive dyes
for cotton require large amounts of water for application
and washoff (8).
One pollution prevention method for the application of
reactive dyes is the pad-batch method. Pad-batch dye-
ing solves these problems without affecting the proper-
ties of fiber reactive dyes. In addition, it improves
productivity and energy savings (65).
Pad-batch dyeing has been used successfully world-
wide and now is being adopted in the United States (11).
It is a reliable, easy-to-control method that is known for
its reliable laboratory-to-production correlation on first-
run dyeings.
In pad-batch dyeing, prepared fabric is padded with a
solution of fiber reactive dyestuff and alkali, then stored
(or batched) on rolls or in boxes and covered with plastic
film to prevent evaporation of water or absorption of
carbon dioxide from the air. The fabric then is batched
for 2 to 12 hours. Washing can be done on whatever
equipment is available in the mill.
Pad-batch dyeing offers several significant advantages,
primarily cost and waste reduction, simplicity, and
speed. Production of between 75 and 150 yards per
minute, depending on the construction and weight of the
goods involved, is common. Also, pad-batch dyeing is
flexible compared with a continuous range. Either
wovens or knits can be dyed in many constructions.
Frequent changes of shade present no problems be-
cause reactives remain water soluble, making cleanup
easy. This method of dyeing is useful when versatility is
required. Water use typically decreases from 17 gallons
per pound to 1.5 gallons per pound, a reduction of more
than 90 percent (65). A full description of pad-batch
dyeing can be found in Section 4.10, "Dyeing."
Processing Bath Reuse. Water from many processes
can be renovated for reuse by a variety of methods.
Several research efforts are underway. In a few opera-
tions, up to 30 percent of the treated wastewater is
recycled directly back from the effluent to the raw-water
intake system with no adverse effects on production. In
some cases, specific types of wastewater can be recy-
cled within a process or department. Examples are dye-
bath reuse, bleach bath reuse, final rinse reuse as
loading bath for next lot, washwater, countercurrent
washing, and reuse for other purposes.
Several treatment strategies also are available to clean
up or renovate water for reuse. Often, no treatment is
needed, or a simple conventional filter step is used. The
most studied methods of renovation are:
• Chlorination (72)
• Ozonation (73)
• Ultrafiltration (74)
These techniques are depicted in Figures 2-6, 2-7, and
2-8, respectively. Laboratory studies have thoroughly
validated the technical and economic feasibility of each
technique, but surprisingly few commercial operations
have adopted these practices in the United States.
Chlorination decolorizes water by saturating it with chlo-
rine gas in a holding tank, making it useful for dyebaths
(72). The dyes, if selected properly, are destroyed with-
out affecting other components of the bath (e.g., buffers,
carriers, leveling agents, salt, dispersing agents). Of
course, the waste generated and the chemicals (with
associated BOD) and energy used are reduced in this
Recycled
Water —<•
Dye
Beck
Storage
Tank
Treatment
Tank
Storage
Tank
SO2
CI2
"la
CilyWater-
Steam-
Pump
Filter
Drain
Pump
Caustic Soda
Drain
Pump
V Drain
Pump
Filter
Drain
Figure 2-6. Flow diagram for Chlorination water treatment system (69).
70
-------
Transformers
UV Lamp
Trap
Row Meters Wash Bottle Sets
Figure 2-7. Ozone generation equipment (70).
Oxygen Air
system. One commercial operation recycles 75 percent
of the dye wastewater (72). A drawback to chlorination
is that it produces chloro-organics in the treated water.
Ozonation has been widely studied and, like chlorina-
tion, has been proven in repeated laboratory trials (73).
The process, however, has not been widely adopted in
commerce. In this method, a generator (shown in Figure
2-7) is used to produce ozone or pure singlet oxygen
(73). Laboratory studies indicate that ozone is more
effective than singlet oxygen, and recent studies have
focused primarily on ozone (73).
Examples of the decolorization ability of ozone for Cl
Disperse Yellow 42, Cl Basic Yellow 11, and Cl Acid Red
151 are shown in Figures 2-9 and 2-10. Depletion of
desirable dyebath auxiliaries is shown in Figure 2-11
(73). Ozonation has been used for multicycle repeat
dyeings in laboratory settings with success and has
been evaluated commercially.
Ultrafiltration has been more widely adopted than the
above reactive chemical treatments. Some advantages
of Ultrafiltration are:
• No undesirable reaction products
• Simpler, safer operation
• Safety
• Effectiveness
• Separate recovery of chemicals and water
Ultrafiltration is essentially the same technology as that
used for caustic and size recovery. Figures 2-8 and 2-12
show the basics of the Ultrafiltration recovery scheme
(74). Membranes are tailored to the required pore size
for removal of the species of interest (see Figure 2-13)
(74). Ultrafiltration can produce 95-percent water recov-
ery in commercial practice (74). These systems have
been widely adopted in commerce and have proven
invaluable. Payback for dyebath recovery is estimated
Scouring and Bleaching System
99,000 gpd
250 Bleach
19 NaOh
4,800 gpd
13 Bleach
1 NaOh
103,000 gpd
286 Bleach
20 NaOh
29,900 gpd
15,200 Salt
Figure 2-8. Recycle of jet dyeing machine flows using Ultrafiltration (71).
71
-------
A Room Temperature
•*• 80°C
200 400 600 800 1,000
Ozone Consumed (mg/L)
Figure 2-9. Ozone decolorlzation of Disperse Yellow 42 (70).
O Basic Yellow 11
• Acid Red 151
2468
Ozone Consumed (mg/L)
Figure 2-10. Dye decolonization by ozone (70).
to be 1.5 years, and shade reproducibility is better than
the reactive methods listed above (74).
Dyebath Reuse
In the 1960s, about 10 to 16 percent of textile wastewa-
ter was reclaimed or recycled (14). Recent improve-
ments, including dyebath reuse, have dramatically
increased the potential for reuse, with corresponding
500
Q.
O.
400
CD
I 300
O Avitone T
• Chemcogen 12-LD
50 100 150 200
Ozone Consumed (mg/L)
Figure 2-11. Ozone oxidation of auxiliaries (70).
cost savings and waste reduction. No current study of
water reuse in textile mills has been published. Dyebath
reuse, one pollution prevention method for water con-
servation, has been shown to reduce flow, BOD, and
COD loadings by up to 33 percent (14). Dyebath reuse
also shows a return on investment in the form of dye,
chemical, and energy savings that pretreatment does
not. Savings, installation costs, and operating expenses
are site-specific, but a typical payback period is 13 to 20
months (14). This is discussed in detail in Section
4.10.6.5.
Bleach Bath Reuse
Cotton and cotton blend preparation (e.g., desizing,
scouring, bleaching) are performed using continuous or
batch processes and usually are the largest water con-
sumers in a mill. Continuous processes are much easier
to adapt to wastewater recycle/reuse because the waste
stream is continuous, shows fairly constant charac-
teristics, and usually is easy to segregate from other
waste streams.
Waste-stream reuse in a typical bleach unit for polyes-
ter/cotton and 100-percent cotton fabrics would include:
• Recycling J-box and kier drain wastewater to satura-
tors.
• Using countercurrent washing.
• Recycling continuous scour washwater to batch
scouring.
• Recycling washerwater to backgray blanket washing.
• Recycling washerwater to screen and squeegee
cleaning.
• Recycling washerwater to color shop cleanup.
• Recycling washerwater to equipment and facility
cleaning.
• Reusing scour rinses for desizing.
• Reusing mercerizer washwater for scouring.
72
-------
Tubes
Permeate
Figure 2-12. Typical membrane configuration for ultrafiltration
(72).
• Reusing bleach washwater for scouring.
• Reusing water jet loom washwater for desizing.
• Recycling kier drains to saturators.
Preparation chemicals (including optical brighteners and
tints), however, must be selected in such a way that
reuse does not create quality problems such as spotting.
Batch scouring and bleaching are less easy to adapt to
recycling of waste streams because streams occur in-
termittently, drains generally go into pits and are not
easily segregated, and batch preparation steps fre-
quently are combined. With appropriate holding tanks,
however, bleach bath reuse can be practiced in a similar
manner to dyebath reuse, and several pieces of equip-
ment are now available that have the necessary holding
tanks (67). The spent bleach bath contains all of the
alkali and heat necessary for the next bleaching opera-
tion (67). Peroxide and chelates must be added to re-
constitute the bath. Like dyebath reuse, the number of
reuse cycles in bleach bath reuse is limited by impurity
buildup. The main impurities are metals, such as iron,
that can interfere with the bleaching reaction.
Continuous Knit Bleaching
New types of rope bleaching units for knits featuring 6-
to 12-stage jet transport systems have made continuous
bleaching of most knit styles possible (70). These units
were introduced in the late 1970s and typically produce
40 pounds per minute of knit fabric or more than 1 million
pounds per month based on a three-shift, 6-day opera-
tion. These machines have become very popular with
large knit processors because of their flexibility and
ability to conserve energy, water, and chemicals. They
also have complete countercurrent capabilities built in.
These units are being promoted for use in afterwashing
fiber reactive and other types of dyes (e.g., after pad-
batch dyeing) in addition to use as continuous knit
preparation ranges. This is discussed further in Section
3.19, "Pollution Prevention Through New Equipment."
0.0001
0.001
0.01
10.0
Microns
Figure 2-13. Tangential flofiltration (71).
73
-------
Final Rinse Reuse as Loading Bath for Next Lot
One simple technique that saves water and, in some
cases, BOD loading is to reuse the final bath from one
dyeing cycle to load the next lot. This technique works
well in situations where the same shade is being re-
peated or where the dyeing machine is fairly clean.
A good example of this technique is acid dyeing of nylon
hosiery. The final bath usually contains an emulsified
softener that exhausts onto the substrate, leaving the
emulsifier in the bath. This technique can serve as the
wetting agent for loading the next batch, thus saving the
water, heat and wetting agent, and associated BOD.
2.2.7.5 Waterless Alternatives
Several waterless processing methods deserve com-
ment. The most widely practiced method is mechanical
finishing, which is described in Section 4.12, "Finishing."
In the area of preparation and dyeing, waterless proc-
esses are based on supercritical carbon dioxide fluid
(SCF) technology. These processes use no water, and
drying is simply a matter of letting the carbon dioxide
flash off, which happens immediately upon releasing the
supercritical pressure. One advantage of these systems
is that commercially available disperse dyes for polyes-
ter can be used, so no special colorants have to be
developed. Waterless processes are being used only in
laboratories and pilot plants at this time, but they de-
serve attention.
Waterless mercerization can be accomplished by the
use of liquid ammonia, which is recovered and reused.
Liquid ammonia mercerization is effective and practiced
on a wide scale commercially. One promising area of
research at this time is the use of ammonium thiocy-
anate in the ammonia bath to elevate the boiling point
of the liquid ammonia to room temperature, reducing the
need for expensive cooling systems to run the liquid
ammonia mercerization process.
Another laboratory development is the use of powder
colorants and xerographic printing techniques for water-
less textile coloration processes.
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66. U.S. EPA. 1978. Pollution control in textile mills. In: Environ-
mental pollution control, textile processing industry. Prepared for
the Environmental Research Information Center by Lockwoode
Green Engineering. Washington, DC.
67. Brenner, E., T. Brenner, and M. Scholl. 1993. Saving water and
energy in bleaching tubular knits. Amer. Dyestuff Reporter
(March), p. 76.
68. Evans, B.A. 1982. Potential water and energy savings in textile
bleaching. In: Water conservation technology in textiles—State of
the art. WRRI Bulletin 46 (May). Water Resources Research
Institute, Auburn University, AL.
69. North Carolina Department of Natural Resources and Community
Development, North Carolina Department of Environment,
Health, and Natural Resources. 1985. Pollution prevention tips:
Water conservation for textile mills. Pollution Prevention Program,
Raleigh, NC.
70. Smith, B. 1989. Pollutant source reduction: Part 4—Audit proce-
dures. Amer. Dyestuff Reporter (June), p. 31.
71. North Carolina Department of Environment, Health, and Natural
Resources. 1993. Case studies-SIC 2000-2300: Textile mill prod-
ucts and apparel/other finished products (September). Raleigh, NC.
72. Mills, J.R. 1982. Technical and economical feasibility of treating
and reusing textile dye wastewater. In: Water conservation tech-
nology in textiles—State of the art. WRRI Bulletin 46. Water Re-
sources Research Institute, Auburn University, AL (May).
73. Tmcher, W.C., and L. Averette. 1982. Direct dyebath reuse
through spectophotometric and ozonalysis techniques. In: Water
conservation technology in textiles—State of the art. WRRI Bul-
letin 46. Water Resources Research Institute, Auburn University,
AL (May).
74. Woerner, D.L. 1993. Utilization of membrane filtration for dyebath
re-use and pollution prevention. COTTECH Conference, Raleigh,
NC (November 11-12).
75. Grizzle, T.A. 1982. Ultrafiltration applications in the textile indus-
try. In: Water conservation technology in textiles—State of the art.
WRRI Bulletin 46 (May). Water Resources Research Institute,
Auburn University, AL.
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Chapter 3
General Pollution Prevention Approaches Applicable
Throughout the Textile Industry
In companies with superior environmental management
programs, pollution prevention is a daily activity that
applies to all business functions. This chapter describes
general principles and approaches to pollution preven-
tion that are applicable to all types of textile operations,
regardless of the processes they us& or the products
they produce.
3.1 Building Blocks of an Effective
Pollution Prevention Program
3.1.1 Management Commitment
A prerequisite to a successful pollution prevention pro-
gram is firm commitment at the management level.
Companies should develop and adopt a comprehensive
policy that definitively states their commitment to pollu-
tion prevention principles. The policy should include 1)
a general management statement emphasizing the im-
portance of pollution prevention and the company's
commitment to pollution prevention principles, 2) de-
fined goals or targets for pollution prevention, 3) alloca-
tion of organizational and technical resources to
pollution prevention, and 4) a method for tracking pollu-
tion prevention performance (1).
3.1.2 Employee Commitment
A well-planned pollution prevention program is built
upon a framework of employee involvement and com-
mitment. Experience has shown that employees are
extremely knowledgeable about sources of waste and
pollution in their facility and are an excellent source of
ideas for reducing waste and preventing pollution. Thus,
management must foster employee awareness in order
for a pollution prevention program to be successful.
Chapter 5 provides some concrete guidance on how
to get employees involved in the pollution prevention
initiative.
3.1.3 Low-Technology Approaches
A surprising number of successful pollution prevention
ideas are based on simple, low-technology principles.
Adopting these approaches can help facilities avoid ex-
pensive waste treatment, disposal, and liability costs. In
the United States, approximately $75 billion is spent
annually for waste treatment. This figure is expected to
rise by 33 percent to $100 billion in the future because
of new air pollution regulations (2). Pollution prevention
can produce outstanding results for a fraction of this
cost, often with a rapid return on investment.
Initial pollution prevention efforts in a textile operation
should focus on low-technology approaches, which
have the highest return on investment and encourage
further progress. Figure 3-1 shows that the "worst" mills,
which do not practice even common pollution prevention
techniques, can have the greatest decrease in pollution
with the least expenditure simply by applying known,
proven technologies, such as those listed in Table 3-1 (3).
Net
Waste
Discharge
Worst —
Average —
Best —
State
of the •
Art
Minimum
Effluent -
Mill
Practical
Limit-
(Zero)
Theoretical
Limit"
Existing
Technologies
in Use
Proven Technologies Not
in Commercial Use
Developing Technologies
Unknown Technologies
To Reduce Waste
Outside Waste
Processing
Technologies
Time
Money
Effort
Figure 3-1. Waste reduction achievements as a function of pol-
lution prevention efforts over time.
77
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Table 3-1. Known Pollution Source Reduction Strategies That
Are Widely Used In Textiles
• Design slaga planning for processes
• Equipment maintenance and operations audit
• High extraction, low carryover process step separations
• Incoming raw material quality control
• Maintenance, cleaning, and nonprocess chemical control
• Material utilization in cutting and sewing
• Optimized chemical handling practices
• Raw material prescreenlng before use
• Segregation, capture, recycle, and reuse of wastes
• Training
• Development of a conservationist worker attitude
Figure 3-1 illustrates the concept of receiving the most
return for the least time, effort, and money by using
technology transfer to carry out known pollution preven-
tion practices (3). Many large companies employ an
environmental staff person to coordinate pollution pre-
vention activities. This person serves as the expert fa-
cilitator for technology transfer of pollution prevention
between operations and processes (2). The coordinator
at each site can review information from other sites and
identify pollution prevention opportunities, a critical part
of general pollution prevention efforts (1).
Eventually, as a mill's pollution prevention program be-
comes more sophisticated, and the mill has adopted all
appropriate, existing, and proven technologies, it must
seek out new technologies. The easiest technologies to
implement are those proven in other industries. For
example, Section 3.18, "Improved Process Control," de-
scribes a research area that involves the adoption of
known aerospace techniques (real-time, adaptive, mul-
tichannel control using fuzzy logic or neural networks).
by the textile industry. Technologies that have been
successful in other industries, however, may be more
expensive to adopt than same-industry technologies
and have a lower probability of success, resulting in a
lower return on investment and a flatter slope on the
cost/benefit curve (see Figure 3-1) (3).
Even more expensive and of less immediate benefit is
investment in the development of new technologies and
new science. Many companies inappropriately bypass the
implementation of known technologies and immediately
investigate new technologies and new science. This type of
investigation is appropriate only after completing pollu-
tion prevention activities with known technologies, or-
derly work practices, optimization of processes, and
training (3). Future improvements will use known but un-
used technologies (e.g., technology transfer from other
industries), new technologies based on known science,
and perhaps even the developments of new science
(see Table 3-2 for examples of these technologies).
3.1.4 High-Technology Approaches
The discussion of low-technology approaches above
does not imply that high-technology approaches are
inappropriate. Once a mill has a good framework for
pollution prevention, high-technology innovations are a
far more effective long-term approach than "process
tweaking." Orderly work practices pay big dividends in
the short-term, but new technology is important for long-
term success. Radical redesign of processes, including
changes in raw material selection, is an essential com-
ponent of a long-term pollution prevention program (1).
3.1.5 Long-Term Commitment
Persistence is important, and a sustained effort at pol-
lution prevention must be made over a long period to
see complete results. The pollution prevention plan
should begin with commitment and training, and con-
tinue through the pollution prevention techniques de-
scribed below, from low-technology to high-technology
approaches, then to new technology development. Mills
usually can achieve significant results without major
capital expenditure, while simultaneously reducing costs
and increasing profit (4).
3.1.6 Documenting Accomplishments
Textile facilities should set internal goals and document
their progress. For example, the chemical industry (sup-
pliers of textile chemicals) reports it has achieved a
50-percent reduction in hazardous waste and a 20-per-
cent reduction in wastewater by applying the pollution
prevention techniques listed in Table 3-3. These findings
were based on a survey of 681 factories (1). By docu-
Table 3-2. Future Pollution Prevention Innovations for the
Textile Industry
Better risk assessment, methods, data, and procedures
Better-informed customers, designers, managers, and suppliers
Disposal facilities for captured waste
Optimized chemical handling practices
Higher purity raw materials
Improved waste audit procedures
Improved standard test methods and definitions
Less disinformation and politics
More global, integrated view of manufacturing
More technology transfer
More recycling opportunities
More markets for waste
More chemical expertise and general industry competence
78
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Table 3-3. Pollution Prevention Techniques in the Chemical
Industry
• Process change
Modified operating procedures
Advanced process control
Substituted chemicals
Higher quality materials
Recycling of wastes
Direct reuse in the process
Direct reuse in another process
Regenerations for reuse
Sale of by-products
Improved waste treatment
Waste filtration
Waste decantation and separation
Administrative controls
Minimization of washdown
Reduced cleaning frequency
Longer turnaround time
Improved spill control
Segregation of hazardous and nonhazardous waste
Discontinuing manufacture
menting and publishing their success, they provide fur-
ther stimulus to other facilities to investigate pollution
prevention.
3.1.7 Right-First-Time Production
One very important principle in textiles is right-first-time
production, which reduces waste by avoiding chemically
intensive adds and reworks (4). Right-first-time produc-
tion is not discussed as a pollution prevention technique,
but a large body of literature and experience exists on
improving right-first-time production (5). The amount of
off-quality production runs and reworks in mills varies
greatly, and the better mills have a greater cost and
pollution prevention advantage over the others (5).
3.2 Design-Stage Planning for Facilities,
Processes, and Products
The planning stage for new processes, products, and
facilities is essential because it offers the opportunity to
design in pollution prevention. Ultimately, pollution pre-
vention must become integral to all parts of the textile
operation (i.e., all products, processes, and aspects of
facility operations, including suppliers and customers).
The main points to understand regarding design-stage'
planning are:
• Product, process, and facility technfcaf design criteria
that can reduce pollution exist and are well known
(see Chapter 4).
• For pollution prevention to be successful, the de-
signer, manufacturer, and customer must be involved
and work together.
• Pollution prevention through design is facilitated by
technical knowledge; effective communication be-
tween the designer, manufacturer, and customer; es-
tablishment of priorities and pollution prevention
goals; and a willingness to try new ideas.
3.2.1 Design-Stage Planning for Processes
Design-stage planning for processes focuses on arrang-
ing production activities in such a way as to avoid the
generation of pollution and waste (4). Although pollution
prevention can produce substantial gains through
tweaking or optimizing existing processes, effective,
long-term pollution prevention requires an examination
of processes at the fundamental design level to improve
quality and reduce costs and waste (6). Berglund pre-
sents an interesting way of thinking about design-stage
planning in Table 3-4 and Figure 3-2 (7).
This section focuses on machinery selection and chemi-
cal selection as two ways of altering processes at the
design stage to reduce pollution.
Table 3-4. Suitability of Waste Management Options
Checklist (7)
Technical
• Is technology available and usable without modification?
• What major equipment modifications are needed?
• Are major waste modification or pretreatment needed?
Environmental
• How will waste be reduced in volume or hazard?
• Will secondary releases, now or in the future, result in new air,
water, or solid waste pollution problems?
• Could the technology result in new worker safety problems?
Regulatory
• Will the technology result in wastes of less regulatory concern?
• Can permits realistically be obtained in a reasonable timeframe
for the technology?
« Will additional regulations be imposed that could result in
additional air, water, and solid waste controls?
Public Acceptance
• Will the use of technology to reduce the waste at the proposed
location be acceptable to the citizens (or political groups)
affected by the operation?
Economic
• What is the cost compared with other technologies?
79
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Conception
(Laboratory Studies)
Pilot Plant Program
Process Definition
Process Flow Diagram
Mechanical Completion
Definition of Technology
Publication and Approval
Process Safety Review
Facilities Scope Package
Detailed Design
Health Safety and
Environmental Technology
Endorsement
Source Reduction I: Process
Source Recycle
Source Treatment
Source Reduction II: Operation
Figure 3-2. Waste reduction and new technology development (7).
3.2.1.1 Machinery Selection
A substantial part of the current design effort in textile
machinery focuses on reducing water consumption and
preventing pollution (8). To stay abreast of these devel-
opments, process managers must constantly stay in-
formed about new types of machinery. Currently
available machinery that has proven to be effective in
reducing pollution and water consumption includes (8):
• Ultra-low-bath ratio dyeing machines.
• Continuous dyeing ranges for continuous knits.
• Automatic dispensing systems for dyes and chemicals.
• Continuous preparation ranges.
• Very high-extraction systems, including centrifugal,
vacuum, and Mach nozzles.
• Improved control systems.
These types of systems will be adopted more and more
as the costs of water, effluent treatment, and waste
disposal rise. Within a few years, most current machin-
ery will be outdated and subsequently replaced by new,
emerging technology. State-of-the-art machinery is al-
ways changing, and textile processors must stay current.
3.2.1.2 Chemical Selection
Most textile processes use an array of chemicals to
accomplish or facilitate specific tasks. Often, textile
manufacturers rely on the advice of chemical vendors
when choosing which chemicals to use. Although ven-
dors can be an excellent source of information concern-
ing the use of chemicals, all textile operations should
have sufficient internal chemical expertise to enable
them to assess the need for chemicals independently
and to evaluate and select chemicals for use in the mill
only after consideration has been given to nonchemical
alternatives. Several related ideas are discussed in de-
80
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tefl in Sections 4.4, "Chemical Specialties," and 4.5,
"Chemical Commodities."
Considerable progress can be made toward eliminating
some chemicals (and the associated costs and pollu-
tion) if a processing manager understands how to con-
trol processes mechanically, rather than relying on
chemicals to compensate for mechanical inadequacies.
An example using knit design is discussed in detail in
Section 3.2.2.2. Table 3-5 offers several additional ex-
amples of mechanical alternatives.
These examples illustrate the kind of substitution for
chemical processing that should be considered in textile
manufacturing operations. When problems arise in a
process, the first response should be to go back to the
basics of the process, not add a chemical to remedy the
situation. Finishing is a particularly important area in
which mechanical effects can often be substituted for
chemical agents. Many examples of mechanical substi-
tutions are discussed in the following sections and in
Section 4.12, "Finishing."
Table 3-5. Examples of Mechanical Processes That
Substitute for Chemical Processing Assistants
Chemical
Processing
Assistant Mechanical Substitute
Dyebath lubricants
Specialty leveler
Defoamer
Soil release agent for
cotton fabric
Solvent scour to
remove knitting oil
from cotton knits
Adjust machine speed, plaiter action
Get), and reel speed (beck)
Control dye exhaustion by controlling
dye, salt, chemical addition, and rate of
heating
Remove high-foaming chemicals from
process recipes
Cotton is naturally soil-releasing, so
the best strategy is to find out which
finishing chemical additive is causing
soil retention, then eliminate it from the
finish recipe
Arrange knitting processes so the oil
does not get on the cloth, and use
self-emulsifying oil
3.2.2 Design-Stage Planning for Products
Many consumers now expect and seek out environmen-
tally well-designed products. To be competitive in to-
day's market, textile manufacturers need to adopt a new
attitude in which they consider product properties re-
quired by the customer, including environmental as-
pects, at the design and raw material selection stage (9).
For example, fiber, yarn, and fabric waste must be elimi-
nated or preplanned to facilitate recycling (10). Shades
and colors should be selected that use the most envi-
ronmentally benign dyes. Textile manufacturers wishing
to improve their environmentaf performance need to
remember that textile products are not permanent, and
ultimately, every textile product becomes waste.
One significant driving force toward improved pollution
prevention in product design is the potential economic
benefit. For example, Morris (2) cites a typical case in
which solvent concentrations of 300 parts per million
(ppm) to 350 ppm were found in wastewater from a
fabric-coating operation. Implementation of a pollution
prevention program focusing on product design changes
reduced solvent concentrations to well below 100 ppm
(2). This reduction in pollution can result in significant
,cost savings to the textile manufacturer.
An overview of integrated customer/manufacturer pollu-
tion prevention activity at the global design stage is
presented in Figure 3-3 for a printing facility. In this
model, the customer is involved at important points in
the development of the manufacturing process (11).
Although this example applies only for print pattern de-
velopment, expanded schemes of this type could help
the customer to understand, for example, when a par-
ticular color will require a metal-bearing dye. In this way,
alternatives such as other shades or other substrates
can be developed at the design stage (see also Section
4.17, "Globalization of Pollution Prevention").
3.2.2.1 Identifying and Communicating Problem
Areas
Effectively communicating information about pollution
problems is very beneficial in helping mills achieve gains
in pollution prevention. One example of a problem that
can be addressed partly through improved communica-
tion is the presence of metals in dyeing wastewater.
While the dyers generally know, that a dye contains
metal, they usually cannot remedy the situation because
customer requirements dictate the use of such dyes,
and dyers are not in direct contact with customers. On
the other hand, personnel responsible for sales, sched-
uling, and other customer-related activities generally are
not aware of the environmental issues surrounding cus-
tomer selections and do not know how to address such
issues with the customer.
Mill personnel with responsibilities such as design,
sales, and scheduling should receive training on prob-
lem dyes and be instructed on how to recommend less
polluting alternatives. Simply asking customers if they
are interested in using environmentally preferable tech-
niques and materials for their products may be sufficient.
Mills.rarely do this, although it could potentially lead to
substantial improvements (see Section 4.17, "Globaliza-
tion of Pollution Prevention").
Personnel should also identify problem fabric structures
and blends for the customer. In particular, mills should
target products with poor right-first-time performance as
81
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Customer
Laser
Engraving
>
t
CMP System [»
>
k
tomer |
r ft - I ^^
r
Conventional
Sample
Production
1
f
Normal Bulk
Production
0
•<-
Color Kitchen
Automatic
Sampling
i
r
Color Kitchen
Automatic
Bulk
Improved Design
Seleotion/Colorway Choice
Improved Quality and Speed of Response for Samples
Leading to Increased Productivity
Figure 3-3. Computerization of the preprint process (11).
part of their pollution prevention efforts. A major factor
contributing to pollution problems in the industry today
is the tendency toward short runs, small lots, and just-
in-time (JIT) production. These trends necessitate greater
use of batch processing, which is generally more pollut-
ing than continuous processing. Also, JIT production
requires more frequent changeovers of machines from
one style or color to another to meet changing delivery
schedules. Every changeover has the potential to create
additional waste from startups, stopoffs, and change-
overs. Scheduling becomes less flexible, lot sizes vary,
and machines are often underloaded. Information about
the additional pollution and cost impacts of short-run
production must be made available to those people
making product design and production decisions.
3.2.2.2 Knit Design
Mills must provide knit fabrics to the customer at a
specified shrinkage, width, and yield. In addition, other
properties such as torque, stretch, recovery, and
strength must be within reasonable limits. Unlike woven
fabrics, knits exhibit stretch properties that allow the
fabric to be pulled into nonequilibrium conditions. One
common practice among knit processors is to force a
knit to desired (nonequilibrium) customer width and yield
specifications and then stabilize the knit using resins,
heatsetting, and/or other techniques. This practice oc-
curs for several reasons (some more valid than others),
including:
• Oversold capacity on some machine groups forces
the knitter to knit fabric on the "wrong" machine.
• Scheduling expediency and delivery pressures cause
fabric to be knit on the "wrong" machine.
• Designers, schedulers, knitters, and finishers misun-
derstand knit structures.
• Designers, knitters, finishers, and customers do not
communicate effectively.
• Poor handling causes stretch and makes knitted fab-
ric lose its equilibrium shape.
• The wrong count yarn is used. Correct yarn may not
be available, or it may be too expensive to set up an
inventory of many different yarn sizes to get just the
right yarn for each style of knit fabric.
• The knitting machine setup is incorrect.
Formaldehyde-containing resins often are applied to
cotton and cotton/blend knits for shrinkage control and
sewability (12). Mills can, however, stabilize knits with-
out using chemical additives if the customer specifica-
tions match equilibrium configuration of the knit fabric in
terms of width, yield (weight), and shrinkage, and the
manufacturing process allows for complete relaxation
(9,12). A key to relaxed fabric is to keep the processing
as tensionless and consistent as possible after the knit
has been properly constructed. Commercial knit finish-
ing equipment (e.g., compacting, relaxed drying) is
available that adequately controls width and length di-
mensions of the fabric during processing, allowing the
knit to fully relax (see also Section 4.12, "Finishing") (12).
Computer-aided (technical) design (CAD) of knit fabrics
can help to ensure the correct weight (yield) and shrink-
82
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age of knit goods, eliminating the need for chemical
finishing (9). Furthermore, CAD systems allow the de-
signer to make the correct yarn selection and determine
proper tensions, stitch length, machine cut, diameter,
and other knitting parameters for producing knit con-
structions to customer specifications (12). Selection of
the proper yarn and knitting parameters, followed by
tensionless handling of the fabric, ensures that the fabric
ultimately achieves a relaxed equilibrium configuration.
If the relaxed configuration meets customer specifica-
tions, then the need for chemical finishes is eliminated
(9). In this respect, many mills use CAD knitting systems.
Implementation of improvements in knitting programs
requires the cooperation of other departments because
scheduling may sometimes limit the knitter's ability to
match styles to the appropriate machine, thereby under-
mining pollution prevention efforts. This is especially
true where production needs exceed the capacity of the
available machine (or machine group). The alternatives
usually are either to delay delivery or to knit on another
machine, which means an associated need for chemical
resins (with formaldehyde) to stabilize the fabric at the
customer's specifications (9).
Design programs that can facilitate proper machine
setup are explained in detail in the literature (9, 12).
3.2.3 Design-Stage Planning for Facilities
In many cases, facility design factors are based on
well-known, sound engineering practices. Some of the
more common design factors can be very helpful when
designing new mills or expanding existing mills. In other
cases, optimizing facilities for pollution prevention might
require a departure from existing facility design practice.
Existing facilities most often exhibit design inadequacies
that contribute to pollution in the following areas:
• Bulk chemical tank farms
• Parking lot and roof drains
• Warehouse, shipping, and receiving areas
• Production areas
• Chemical mix areas
3.2.3.1 Bulk Chemical Tank Farms
The design and configuration of bulk chemical tank
farms requires special consideration. Frrom a pollution
prevention standpoint, the most important aspects of
tanks are 1) the arrangement of tanks and their location,
2) control systems for spills, and 3) weed control. Tanks
should be placed in gravel or concrete paved areas,
away from natural drainage paths to waterways (such
as parking lot drains). Incompatible chemical types
should be located in separate tanks and areas. Contents
must be clearly marked; many accidents and even
tragedies have occurred as a result of incompatible
ingredients being pumped into a poorly labeled tank.
Safety showers and eyewashes should be installed
nearby. Tanks should be diked, and drainage of storm-
water from inside of the dike or berm should be sent to
an appropriate waste treatment system. Ample space
should be available for maneuvering tanker trucks. Lo-
cations for such equipment as check valves, pumps,
and sight glasses should be planned carefully, and the
equipment should be maintained regularly.
3.2.3.2 Parking Lot and Roof Drains
Parking lot and roof drains should be kept separate from
sanitary sewer, process water, cooling water, and other
wastewater handling systems. Flows from these drains
should be discharged and monitored separately from all
other wastewater. Furthermore, no drainage from any
ditch should be permitted to flow onto the plant property.
Ditches that originate elsewhere should be closed off or
rerouted around the facility; otherwise, the plant might
assume liability for a problem that began outside the
facility (e.g., a roadside). All water drainage connections
should be properly documented with up-to-date plumb-
ing diagrams.
3.2.3.3 Warehouses, Shipping, and Receiving
Areas
Warehouses and shipping and receiving areas should
be designed with ample space to store materials out of
the way of forklifts and other traffic. Incompatible chemi-
cals should be stored in separated areas. Chemicals,
yarn, and other raw materials should be stored in metal
racks to avoid stacking containers directly on top of each
other. In this way, broken bags, damaged drums, and
the spillage associated with them can be avoided. Ade-
quate vertical clearance (at least 18 inches) to any
sprinkler head should be allowed. No floor drains should
be present in any warehouse and storage areas be-
cause personnel may wash spills down the drain. Any
spills that do occur should be contained and cleaned up
with the proper absorbent and wet/dry vacuums.
3.2.3.4 Production Areas
Material flow in production areas should be well laid out.
Process chemicals should have their own storage areas
near, but not within, production areas. Floors should be
designed for proper drainage and should be sealed.
Smooth, unobstructed access to all areas and all parts
of machines and floor space should be designed in order
to facilitate cleaning.
3.2.3.5 Chemical Mix Areas
Chemical mix areas should be located as close as pos-
sible to the production areas that they serve yet still
remain isolated. An important pollution prevention de-
83
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sign consideration is to avoid long runs of plumbing and
pipes. Generally, material in these pipes becomes a
waste with each changeover (e.g., of color, size). Multi-
plied by the number of changes that occur, this waste
can be significant.
Poor conditions, cramped space, and areas or surfaces
that are hard to clean should be avoided. Valves and •
other water controls should be mounted in highly acces-
sible locations. Hoses in mix areas commonly are left
running continuously because the valves are installed
on a wall in an inaccessible area (e.g., behind the mix
tanks).
3.2.3.6 Novel Design Practices
Sometimes, a departure from current design practice is
necessary. For example, the traditional approach to
wastewater collection has been to collect all wastewater
in a single drain system. Over the years, single drain
systems have given way to multiple water handling sys-
tems. Many mills have multiple wastewater systems
such as:
• Potable water supply.
• Process water supply.
• Noncontact cooling water return systems.
• Boiler condensate water recovery systems.
* Roof, parking lot, and other normal stormwater dis-
charge systems.
• Systems for stormwater from tank farms and spill
containments.
• Sanitary wastewater systems separate from process
wastewater.
• Within-process recycle and countercurrent systems.
* Systems enabling hot wastewater streams to be sent
to heat exchangers.
• Process wastewater collection for treatment.
Further improvements can still be made in wastewater
collection designs, however. Suggestions include dual-
drain systems for process water so that wastewater from
processes can be diverted to its most appropriate des-
tination (recycle, conditioning prior to recycle, treatment,
discharge) (13). Because many new regulations ad-
dress problems that are very expensive to treat, such as
color and salt, segregation of highly concentrated waste
streams might be desirable to limit the volume of such
wastewater that must be treated. Segregation is espe-
cially important for batch processes in which batch proc-
essing bath dumps are the norm. The problem is less
significant with continuous processes because the
wastewater tends to come from a point source more
uniformly over time and can be easily plumbed into
treatment or reuse (e.g., neutralization of an alkaline
stream).
3.3 Enhanced Chemical and Pollution
Prevention Expertise
Current trends in textile management are toward flatter
organizational structures. As a result, education and
training of mill personnel are more important than ever
because a greater need exists for technical under-
standing at the worker and first-line supervisor level
(14). In fact, one purpose of this pollution prevention
manual is to provide materials that can be used to
educate and train workers and first-line supervisors.
Worker training and education can constitute one of the
highest return, low-technology, and low-risk approaches
to pollution prevention and should form the foundation
of any good pollution prevention program.
3.3.1 Training
Employee work practices and attitudes towards pollution
are an important key to success in pollution prevention
programs, especially for companies attempting rapid,
high-impact startups. Employees should be educated
from the beginning about how their jobs relate to waste
and pollution. The dual goals of pollution prevention and
improved quality through right-first-time processing go
hand in hand. Barriers such as poor housekeeping,
training, maintenance, and facilities should be removed
to enhance workers' and supervisors' attitudes (15).
A different and improved working culture can be devel-
oped with an attitude that "wherever there is waste,
there is money to be made" (4). Employees should be
trained to recognize process waste and to realize that
their actions bear directly on the environment and the
success of their jobs (15). Training first-line supervisors
and department managers as well as production em-
ployees is a productive pollution prevention activity with
short-term payback (1).
Pollution prevention should be an integral part of.corpo-
rate policy and worker training programs (16). Ideally,
training should be process-specific and machinery-spe-
cific and thus is best done internally. Employees should
be given specific instructions and appropriate equip-
ment to do their jobs properly (15). Production line and
maintenance employees should be involved in all stages
of training program implementation, evaluation, and up-
dating (16). In addition, orderly and clean work practices
on a shift-by-shift basis are important (1). These prac-
tices should be audited, and the results should be used
for designing periodic retraining (15).
Employee suggestions should be actively solicited and
acted upon (15). Companies that are well managed from
a pollution prevention standpoint encourage all employ-
ees to participate in identifying and solving pollution
84
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problems. Companies that value employee input and act
on their suggestions can count on a steady flow of
creative ideas and solutions. Conversely, nothing stops
employee participation in a pollution prevention program
faster than failure to act on comments and suggestions.
The topics of training should be oriented to real work-
place issues, with emphasis on pollution prevention
practices as described in the following subsections.
3.3.2 Education
A more long-term approach to pollution prevention can
be taken through formalized employee education. Edu-
cation programs are more general and less job-oriented
than training programs. Several specific topics have
been documented in the literature, including:
• The need for an in-depth understanding of chemistry,
reaction kinetics, thermodynamics, fluid mechanics,
and fine-particle technology among process design-
ers. This knowledge is essential to pollution preven-
tion and long-term improvements (1).
• The establishment of corporate-level work groups to
develop and distribute information concerning pollu-
tion prevention engineering, pollution prevention audit-
ing, waste exchanges, and innovative pollution preven-
tion ideas (16). Internal training and education
through process improvement groups are a hallmark
of a few major corporations as they work to improve
their work force. In-house newsletters devoted to pol-
lution prevention topics are another effective way to
communicate information and educate employees.
• The commitment to consider alternatives before add-
ing a new chemical to a process (17). This commit-
ment requires both chemical and process expertise
on the part of the production process designer.
Other areas mentioned below are also important.
In general, most pollution prevention training is best
conducted internally because job-related issues are
very site-specific. On the other hand, general education
can be conducted either internally or externally. Several
useful external training and education mechanisms are:
• Conferences and meetings.
• Equipment and trade shows.
• Trade organizations.
• Televised education.
• Videotape training aids.
• In-plant courses by outside experts or plant technical
personnel. ,
• Correspondence courses from textile colleges.
• Evening classes at community colleges.
3.3.2.1 Trade Organizations, Committees, and
Conferences
A good forum for information exchange is to participate
in trade organizations (18). As an example, over the last
20 years approximately 90 papers specifically address-
ing environmental issues have been presented at the
American Association of Textile Chemists and Colorists
(AATCC) National Technical Conference. Twice as
many papers are probably presented in local and re-
gional meetings of AATCC.
In addition to conferences, many trade association com-
mittees actively concern themselves with pollution pre-
vention in the textile industry. These.include:
• RA 100 of AATCC (Environmental and Safety).
• American Textile Manufacturer's Institute (ATMI) En-
vironmental Committee.
• North Carolina Textile Manufacturer's Association En-
vironmental Committee.
• Carolina's Air Pollution Control Association.
• Northern Textile Association.
Many of the textile trade associations focus strongly on
environmental presentations. In fact, at a recent wool
processing conference, 24 percent of the chemical proc-
essing papers focused on environmental aspects of
wool processing, and 7 percent had environmental is-
sues as secondary themes (19).
Major new processing equipment with pollution preven-
tion potential is shown regularly at international shows
like International Textile Manufacturers Association
(ITMA) (8). Two notable domestic shows are the Bobbin
Show and American Textile Machinery Exhibition
(ATME) International.
3.3.2.2 Televised Education
At colleges and universities with textile programs, textile
courses may be available on video. These videos form
the basis of regular college courses that can be taken
for credit or audited at the undergraduate or graduate level.
Examples of offerings at North Carolina State University
(NCSU), one of the largest textile programs, are:
• Polymer chemistry
• Yarn production systems
• Weaving systems
• Dyeing and finishing technology
• Rheological and mechanical properties of polymers
• Marketing management
•' Apparel technology management
85
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• Spun yarn manufacturing
• Fabric formation and structure
• Fiber science
• Fiber formation (extrusion)
• Preparation and finishing chemistry
• Chemistry of processing assistants
• Physical properties of polymers
• Instrumentation and control systems
• Quality control
* Warp knit engineering
• Composites
• Comfort properties of textiles
These courses offer a high level of education at a rea-
sonable cost.
3.3.2.3 Videotape Training Aids
AATCC, as well as NCSU and other universities, offer
videotape libraries. Facilities can rent or buy these vide-
otapes and use them fortraining. The tapes range in length
from 5 to 50 minutes and cover hundreds of topics.
3.3.2.4 Industrial Short Courses
AATCC, several universities (notably North Carolina Voca-
tional School, NCSU, and Clemson), and numerous industry
consultants offer short courses on specific textile topics.
These courses can be conducted at the mill or off site'using
the facilities of a trade association, university, or other organi-
zation. The duration is typically 1 to 5 days, and many
courses are tailored to the industrial setting. Textile-oriented
short courses for 1994 from AATCC and NCSU covered:
• Textile fundamentals.
• Implementing process improvements.
• Weft knitting.
• Weaving fundamentals.
• Spun yarn manufacturing.
• Pollution prevention in textiles.
• Indoor air pollution.
• AATCC National Technical Conference.
• Reengineering textile and apparel operations.
• Information systems for textile manufacturing.
• Dyeing and finishing fundamentals.
• Quality conference.
• Color science.
• Troubleshooting in textile wet processing.
• Controls conference.
• Presentations at AATCC local and section meetings
and committee meetings.
3.3.2.5 Correspondence Courses From Textile
Colleges
Most major universities offer correspondence courses in
which the student transacts all studies through the mail.
3.3.2.6 Evening Classes
Most universities and community colleges offer a wide
variety of evening classes or classes conducted in regu-
lar time slots to accommodate working students. In
many cases, these classes are taught on demand, so a
textile operation or group of textile operations located in
close proximity can coordinate and arrange for courses
to be offered as needed.
3.4 Equipment Maintenance and
Operations Audit
Poorly maintained equipment leads not only to bad
work, off-quality production runs, high reworks, and poor
employee attitudes, but also to increased pollution. Pre-
ventive maintenance is the solution to these problems
and can be accomplished through proper audits (20)
(see also Chapter 5). In the auditing process, the follow-
ing problem areas should receive special attention:
• Major machinery
• Leaks
• Filters
• Automatic chemical systems
• Chemical measuring and dispensing devices
Employees are an important source of information regard-
ing problem areas, and their reports of problems such as
equipment malfunctions and leaks should receive prompt
attention. Some common problems seen in textile opera-
tions are cited below. These examples are instructive be-
cause they point to potential problems. The main goal is
to create a watchful attitude in employees and an effective
preventive maintenance program for each machine.
3.4.1 Major Machinery
Every major machine should have a checklist for routine
maintenance and an operations checklist. An example for
dye becks is shown in Tables 3-6 and 3-7. A similar check-
list should be available as a training and audit aid for each
machine. In addition, certain types of equipment compo-
nents should receive their own periodic checks. These
include pumps, valves (especially check valves), filters,
86
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Table 3-6. Routine Maintenance Checklist for Dye Becks (22)
• Reel type, shape, cover, speed: compatible with substrate and
dye recipe.
• Idler reel: turns free and true.
• No snags or rough edges in the machine.
• Tangle detector: rake and reel overload.
• Tangle alarm: audible and visible.
• Controller accuracy: temperature and rate of rise.
• Leaking valves: drain, fill, steam types.
• Steam quality available (while other demands are "on").
• Circulating pump and heat exchanger (if any): performance at
operating temperature.
• Location and integrity of temperature sensor,
• Location and evenness of steam injection when heating and
also when holding at 140°F and 200°F and end-to-end
temperature differences.
• Overhead steam (if any). ,
• Damper and door (front and rear) operations.
• Damper ability to exhaust, fumes.
• Fill water temperature.
Table 3-7. Operations Checklist for Dye Becks (22)
• Load out the entire cloth.
• Be sure load size is appropriate: 60 to 80 pounds per beck root
is typical.
• Be sure all strands are the same length, because long strands
dye light, and short strands dye dark.
• Load out fully and evenly.
• Sew seams straight, with no twist in the strands, and no holes
in seams.
• Control the liquor level according to the fabric; too high gives
tangles and "swimming" of cloth, and too low gives abrasion,
streaks, blotchy dyeing.
• Schedule light shades first, and dark shades later.
• Base electrolyte and buffer on the bath, not the cloth.
• Ensure moderate ballooning by allowing some foam or air to
collect inside tubular goods; inflate with airhose if needed.
• Be sure to take a slow rate of rise near the critical points, such
as wet Tg and dye strike temperature.
• Do not boil a beck—tangles will result.
• Use overhead steam to prevent drips, especially in winter.
• Be sure doors and dampers are closed when running at high
temperatures to avoid cracks and drips.
• Be sure goods have adequate turnover rate—once per minute
is typical.
level switches, and flow or pressure regulators. Each
machine should be inspected for integrity and proper
performance at regular intervals. The most common
defects are missing guards; frayed or loose electrical
cords; water, steam, and compressed air leaks; and im-
proper operation of controls. In addition to process machin-
ery, maintenance checks should be made on utility serv-
ices (e.g., boilers, hot water systems, thermal insulation
ducts).
3.4.2 Leaks
Nagar (21) estimates that annually, 100 million gallons
of lubricating oils from industrial manufacturing plants
are lost to the environment through leaks and other
preventable circumstances. In textiles, lubricants are
widely used as crankcase oil, heat transfer fluids, trans-
former oils, process oils, machine lubricants, bearing
greases, and other uses. A leak of only three drops per
second from a faulty seal can discharge 1,300 gallons per
year to the environment. Proper leak control and preven-
tive maintenance can avert 75 percent of all leaks (21).
Steps to prevent leaks include: 1) designing systems
with minimum numbers of joints and potential leakage
points, 2) using proper materials in constructing sys-
tems, and 3) training maintenance workers to recognize
leaks and properly repair them. Also, facilities should
ensure that lubricants do not become contaminated in
service, requiring replacement more often than neces-
sary. For textiles, contamination originates with incom-
patible greases from other parts, lint, packing/gasket
fragments, rust, paint flakes, pipe scale, and water. A
checklist for reservoir maintenance includes fitting lids
with proper gaskets and secure seals, proper oil filters,
and air filters over breathers. Lubricants also can break
down thermally, so oil that is compatible with machine
operating temperatures must be used (21).
Housekeeping and maintenance are essential for leak
control. Audits should be carefully conducted for broken
and leaking pipes, leaking drums, leaking pumps and
valves, and running hoses. Small leaks can contribute
large amounts of pollution and high costs if undetected
or left unchecked. For example, a water leak smaller
than the radius of a pencil has been estimated to cost
as much to the company in a year as a week's paid
vacation for one worker (15). DuPont's division for or-
ganic chemicals, plastics and synthetic fibers deter-
mined that leaking pump seals produced 450 kilograms
per day of total organic carbon (TOC) load. Correcting
this problem reduced pollution loads to the treatment
facility by 50 percent while producing $7 million in sav-
ings and a dramatic reduction in permit violations (23).
3.4.3 Filters
Maintenance of filters and filter media is another area in
which to focus pollution prevention efforts. Filters are
used in many processes as a primary control treatment
for lint removal and water purification.
Screen filters are commonly used to keep suspended
solids out of the effluent by capturing them at the source
(a primary control method). To be effective, filters must
87
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be cleaned on a regular basis. Most importantly, the
recovered lint and debris filtered from the bath must be
removed and landfilled or recycled as waste fiber, not
dumped back into the drain. Often, however, workers
clean out lint filters in dyeing machines or bleach ranges
and discard the lint into the floor drains.
Many mills use various types of filters for water purifica-
tion, including sand and gravel, activated carbon, water
softeners, and ion exchange. In general, these filters
require careful maintenance, and the filter media must
be periodically cleaned and replaced. Many bleaching
and dyeing problems stem from impurities in incoming
water and ineffective filter systems, or neglected filter
media maintenance.
3.4.4 Automatic Chemical Systems
Routine maintenance is essential for automatic chemi-
cal feed systems and equipment such as bulk chemical
storage tanks, pumps, and valves. These systems are
an excellent aid to pollution prevention because they
tend to reduce routine working losses and small-scale
spills. Bulk automated systems increase the chance of
a catastrophic release of chemicals. Therefore, routine
preventive maintenance for bulk automated chemical
dispensing systems is essential. Generally, a weekly or
monthly inspection of all system components is recom-
mended. Typical points of attention are:
» Tank integrity.
• Label viability and correctness.
• Spill-containment integrity around tank, pipes, pumps,
valves, and lines.
• Availability of spill control equipment and sorbent.
• Condition of off-loading devices (e.g., couplings,
blowers).
• Condition of eyewash and safety shower in off-load-
ing area.
• Sight glass integrity and protection.
• Pumps.
• Valves.
* Lockouts and other pump controls.
• Other site-specific items.
3.4.5 Calibrations of Chemical Measuring
and Dispensing Devices
Any device used to measure or dispense chemicals to
a process should be regularly calibrated or verified for
accuracy. This includes drug room scales and automatic
dispensing systems, as well as other devices used to
measure and dispense chemicals.
3.4.6 Employee Input
Employees are a vital source of information concerning
equipment in need of repair. Employee reports should
be addressed immediately, not only to correct equip-
ment problems, but also to convey management's com-
mitment to pollution prevention, which will hopefully
translate into worker commitment (15).
3.5 Chemical Alternatives
This section provides information about preventing pol-
lution in textile operations through chemical substitu-
tions and presents a few widely applicable chemical
substitutions as examples of what is possible and how
to initiate and conduct a substitute evaluation. Chemical
substitutions also are covered in sections of this manual
that cover specific individual processes. For example,
information on substituting non-metal-bearing dyes for
metal bearing dyes may be found in Section 4.3, "Dyes."
Textile manufacturing is a chemically intensive process,
so a primary focus for pollution prevention should be on
textile process chemicals (20). Best management prac-
tices for preventing pollution involve substituting less-
polluting chemicals where possible, as opposed to
treating chemical-bearing waste streams (20). Substitu-
tion can eliminate the waste load and the need for
treatment, whereas treatment can simply result in trans-
fers of pollutants to solid waste (sludge) or air emissions
(volatile organic compounds [VOCs]). A wide variety of
chemical substitutions can be made in textile wet proc-
essing. Many authors have described these substitu-
tions (15, 24-27), and the sections below review some
of these substitutions (see also Sections 4.4, "Chemical
Specialties," and 4.5, "Chemical Commodities").
Textile mills often view pollution as a chemical supplier's
problem (28). In part, this is because suppliers often
withhold composition and pollution information about
their products as "proprietary trade secrets." The sup-
plier should take responsibility, however, for providing
adequate information that enables mills to make reason-
able environmental evaluations, even on proprietary
products. At the same time, the mill has the ultimate
responsibility for pollution because suppliers cannot
control the specific conditions of use of their products in
terms of:
• Amount used
• Manner of handling
• Other chemicals used in the processing bath
• Process conditions
• Equipment used
• Possible in-process reactions
• Quality of waste treatment available
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• Technical qualifications of the user
In other words, the supplier and the mill share respon-
sibility for assessing chemical requirements, use condi-
tions, and environmental impact. The supplier assumes
a certain degree of responsibility for proprietary chemi-
cals, yet the mill also must understand that the chemical
only performs as promised (in terms of both processing
characteristics and environmental impact) if used prop-
erly. Ongoing consultation with chemical suppliers is key
to a successful pollution prevention program (see also
Section 4.17, "Globalization of Pollution Prevention").
3.5.1 Chemical Substitutions
Opportunities for chemical substitution vary substan-
tially among mills because of differences in:
• Environmental conditions: Permit requirements, am-
bient air quality, receiving water classifications, etc.
• Process conditions: Availability of processing equip-
ment, quality of control systems.
• Product: Fiber blends, market and customer require-
. ments, marketing and management philosophy.
• Raw materials: Incoming fiber and water quality, other
raw material interactions.
Nevertheless, examining general examples and typical
success stories from other companies can be instructive
because they demonstrate the use of chemical substi-
tution for preventing pollution. Typical pollution preven-
tion opportunities related to chemical alternatives are
noted below:
• Chemical expertise: Every effort should be made to
understand the chemistry of the process (see Section
3.3, "Enhanced Chemical and Pollution Prevention
Expertise," for more information). Ensure that the
chemical being considered is appropriate to the tech-
nical needs of the process. Do not use dyes or chemi-
cals of unknown constitution.
• Chemical information: Mills should insist on all nec-
essary information concerning environmental aspects
of a chemical's use before accepting it for production
or for maintenance use. If the vendor is not forthcom-
ing with environmental information, seek other sour-
ces (see Section 4.4, "Chemical Specialties," for
more information).
• Adopt a conservative approach: Experiments should
be conducted to determine the minimum number and
amount of chemicals necessary in mixes to ensure
adequate performance (15). Many mills use large
quantities of specialty chemical processing assistants
while others use essentially none. This suggests that
factors other than chemical use may account for dif-
ferences in results.
• Identify nonchemical solutions: Sometimes mills add
chemicals (such as defoamers) to counteract inade-
quacies or deficiencies caused by other chemicals or
by process conditions (15). A better strategy is to
identify the process conditions that necessitate the
use of such chemicals and reduce or eliminate them.
• Interdepartmental communication: To reduce the num-
ber and amount of chemicals used, coordination among
departments and plants in multifacility operations is
helpful (and sometimes necessary). The same chemi-
cals often can be used in more than one process or
department, reducing inventory, cost, prescreening re-
quirements, and incoming quality control duties (15).
• Prescreen chemicals: Procedures should be estab-
lished to prescreen all chemicals before use. All al-
ternatives, both chemical and mechanical, should be
considered (27). Further information on prescreening
procedures can be found in Section 4.4, "Chemical
Specialties."
• Manage chemical inventories: Mills should avoid accu-
mulating chemicals when changes are made in the
chemicals used and leftover stock of the old chemicals
remain (15). An important part of chemical optimization
and conservation begins with proper disposal of out-of-
date chemical inventory, or a purchasing policy which
avoids accumulation of obsolete materials.
• Implement quality control: Incoming chemical ship-
ments should undergo testing to ensure that they
conform to standards and vendors should know that
testing is being done (27). Further information on the
procedures for quality control screening can be found
in Section 4.4, "Chemical Specialties."
• Specify the proper chemicals packaging: Intermedi-
ate bulk containers (IBCs) are preferable to bagged
chemicals because they reduce the amount of waste
generated and minimize spills caused by breakage.
• Pay particular attention to non-process chemicals:
Nonprocess maintenance chemicals are a major
source of pollution problems and must be included in
a pollution prevention plan. Particular attention
should be given to the evaluation of maintenance and
laboratory chemicals (15).
3.5.2 Obtaining Information on Substitutions
A significant barrier to evaluating chemical substitutions
is the proprietary nature of many textile chemicals, as
discussed in Section 4.4, "Chemical Specialties," and
above. Several efforts are now underway to develop
databases of environmental information for textile
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Tabto 3-8. Pollution Capability of Some Chemicals/Products
Used In the Textile Industry (20)
General Chemical Type Difficulty of Treatment
Pollution
Category
Alkali
Mineral acids
Natural salts
Oxidizing agents
Starch sizes
Vegetable oils, fats and
waxes
Biodegradable surfactants
Organic acids
Reducing agents
Dyes and fluorescent
brtghteners
Fibers and polymeric
impurities
Polyacrylate sizes
Synthetic polymer finishes
Siliconos
Wool grease
PVA* sizes
Starch ethers and esters
Mineral oil
Surfactants resistant to
biodogradation
Aniontc and nonionic
softeners
Formaldehyde and
N-methylol reactants
Chlorinated solvents and
carriers
Catlonto retarders and
softeners
Biocides
Sequestering agents
Heavy metal salts
Relatively harmless
inorganic pollutants
Readily biodegradable;
moderate-to-high BOD
Dyes and polymers
difficult to biodegrade
Difficult to biodegrade;
moderate BOD
Unsuitable for
conventional biological
treatment; negligible
BOD
* PVA « polyvinyl alcohol.
chemicals to make information available to textile mills
(20, 29-31 ).1
Cooper (20) classified textile chemicals into several
general categories based on their degradability, as
shown in Table 3-8 (20). This classification scheme is
similar to the approach taken by Virkler (31) and shown
in Table 3-9. These classification schemes rate biode-
gradability in terms of the ratio of COD to 5-day BOD.
The literature Indicates that a COD:BOD ratio between
2:1 and 5:1 represents normal degradability for textile
chemicals, and that ratios higher than 5:1 represent
hard-to-treat chemicals (27,31,32). After gaining expe-
rience with this method, however, mills have determined
that certain components of mixtures degrade rapidly
over the 5-day assay period, while others degrade more
slowly but nonetheless sufficiently over a reasonable
period. Such mixtures produce high COD:BOD ratios
based on 5-day BOD tests, compared with the ultimate
Table 3-9. Chemical Classification Scheme for the Textile
Industry (31)
Biofate Class
COD COD/BOD Ratio
1 £1,000,000 ppm 1,000,000 ppm <4
3 £1,000,000 ppm >4
4 >1,000,000 ppm >4
Disposal Class
1 Not RCRAa regulated
2 Regulated as hazardous waste by RCRA
3 Regulated as extremely hazardous waste by RCRA
Air Pollution Class
1 525% VOC
2 <25-50%VOC
3 5£0-75% VOC
4 >75%VOC
Toxicity Class
1 No priority pollutants present
3 Priority pollutants present below regulatory limit
5 Priority pollutants present at or above regulatory limit
a RCRA = Resource Conservation and Recovery Act.
BOD.2 Therefore, one component with a high 5-day BOD
can give the appearance of biodegradability when actually
other components are quite resistant to biodegradation,
and the biodegradation slows markedly after the first few
days. An alternative method of rating biodegradability is
the ratio of COD to 28-day BOD. This method is now
preferred for evaluating chemical biodegradability.3
As the usefulness of these methods is fully assessed,
improved systems of user information might be devel-
oped that preserve the trade secrets of textile chemical
auxiliaries. The characteristics being entered into these
databases are shown in Table 3-10 (30). In addition to
the chemical properties, important information concern-
ing synergisms, chemical alteration during processing,
reactions, and the effects of mixing are included in some
databases (30).
Aside from these efforts and an excellent review of
surfactant properties by Kravetz et al. (33) (see Section
4.4 "Chemical Specialties"), relatively little information
has been published that helps a textile mill select alter-
natives. Most published BOD, COD, and other data are
obsolete within a few months or years as products
change. With that caveat, published BOD and COD
information on several commercially available products
is shown in Table 3-11. This serves as a point of refer-
ence in comparing future test data. Information on major
concerns such as aquatic toxicity and ultimate environ-
1
Moore, S. and B. Smith 1994. Personal communication between
Samuel Moore, Burlington Research, and Brent Smith, Department
of Textile Chemistry, North Carolina State University, Raleigh, NC.
See footnote 1.
3 See footnote 1.
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Table 3-10. Environmental Database Parameters (37)
Common name
Synonym
Chemical name
CASa Registry number
Molecular formula
Molecular weight
Melting point
Boiling point
Density
Vapor pressure
Vapor density
Saturation concentration
Water solubility
pH or pKa
Octanol/water partition coefficient (KoW, or LcgP)
Sorption partition .
Coefficient to organic carbon (KoC)
Henry's Law constant or air-water partition coefficient
Flammability
BOD
COD
Theoretical oxygen demand (TOD)
Total organic carbon (TOC)
Odor index (Ol)
Color
Metals
Suspended solids
Total solids
Halogens
Bioconcentration factor (BCF)
Ecological magnification (EM)
Activated sludge respiration inhibition
Aquatic toxicity
Polytoxicity
Half-lives in the environment
—Air
— Surface water
— Ground water
— Soil
— Sediment
— Biota
Environmental fate rate constants or half-lives
— Volatilization/evaporation
— Photolysis
— Oxidation or photo-oxidation
— Hydrolysis
— Biotransformation/biodegradation
— Bioconcentration uptake and elimination constants
Fate factors
— Air
— Water
— Solid
— Product
Biodegradability index
Mixing characteristics/process
— Chemical
— Reaction
— Residues
Table 3-10. Environmental Database Parameters (37)
(Continued)
Oxidizing agent
Reducing agent
Acid
Base
Metals
Salts
OECDb procedures
— Biodegradability test OECD 301D
, — Biomass toxicity test OECD 209
— Acute test OECD 202 part I and II, OECD 203 and 204
a CAS = Chemical Abstract Service.
b OECD = Organization for Economic Cooperation and Development.
mental fate is not available in most cases (34). For
further information, see Sections 4.3, "Dyes," 4.4,
"Chemical Specialties," and 4.5, "Chemical Commodities."
3.5.3 Typical Substitutions
Some typical substitutions in textile operations that have
been reported in the literature are cited below. These
examples illustrate not only the types of substitutions
that can be made but also the processes used to evalu-
ate substitutes, including identifying the tradeoffs in-
volved. Many authors have addressed this topic (15,20,
24-26, 35, 36).
Modak (24) has reported several useful chemical sub-
stitutions, most of which are discussed in other parts of
this document:
• Synthetic thickeners for printing in place of kerosene.
« Synthetic warp sizes for starch.
• Surfactant substitutions to reduce BOD and aquatic
toxicity.
• Permanent adhesives in printing instead of gums.
• Nonmetal dyes for metal-bearing types.
• Formic acid for acetic acid in dyeing to reduce BOD.
In addition, the U.S. Environmental Protection Agency
(EPA) (36) made the following suggestions in the devel-
opment document prepared in support of the original
effluent limitations for the textile industry:
• Biodegradable surfactants for nonbiodegradabie de-
tergents.
• Peroxide or periodate for chrome oxidizers (reduces
metal).
• Sulfuric acid for soap in wool fulling (reduces BOD).
• Mineral acids for acetic (reduces BOD).
• Nonionic emulsifiers plus mineral oil for olive oil in
wool carding.
• Warp size substitutions.
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Tabta 3-11. Published BOD and COD
Chemical
Namo
Acetic add (56%)
Adhesive TQ-17
Ammonium sulfate
Ghomabind S
Chemlube SL
Conco NI-100
Deltaclean 503
Dellaset K 650
Fabritone PE
Finish mix A (1)
Finish 144
Finish mix B (2)
Foam stabilizer 314
Foaming agent FT
Gtolergo 107
Hemltone PE
Hipochem SR
Hipochem TFXI
Hipochem RPS
Hipochem TFX-1
Hfpochem GEP
Hipochem PEK
Hipochem MS
Hipochem DOC
Hipochem EFK
Hipochem QEP
Hipochom WSS
Hydroquest 444
LubSoft NLS
Machine cleaner 417
Madoll 909
Madoil 934
Madoil 966
Magrastop TA 637
Nocurl WPC
Nonstlx84
Patsoft 1261
Racaiev GR
Rapidase XC-T
Raycafix EDS
Reactodye
Reg Foam JFK-66
Revatol SP
Rexwel N-35
Sandoluba NV
Scour Ait
Scour TER
These substitutions
Products Used
Vendor
Commodity
Pioneer
Commodity
Chematron
Chematron
NA
Delta
NA
Patchem
Internal mix
High Point
Internal mix
Vatehem
Patchem
Glotex
High Point
High Point
High Point
High Point
High Point
High Point
High Point
High Point
High Point
High Point
High Point
High Point
Hydrolabs
Lyndail
NA
Madison
Madison
Madison
Tanatex
Consolidated
Nutex
Patchem
Raca
NA
Rayca
IVAX
Parachem
Sandoz
NA
Sandoz
NA
Consolidated
also are revii
Data for Selected
in Textile Operations
BOD
350,000
9,000
18,000
23,300
114,000
162,000
516,000
18,000
76,500
6,800
115,500
14,300
12,000
258,000
102,000
288,000
270,000
680,000
750
680,000
60,000
750
730,000
290,000
140,000
<300
350,000
8,300
33,000
20,300
600
3,360
2,700
100,500
<300
220,000
70,500
102,000
54,000
6,800
NA
43,500
6,000
162,000
245,000
321,000
15,800
3wed throu
COD
446,000
NA
NA
NA
NA
NA
NA
NA
NA
118,900
961,500
34,700
NA
NA
NA
NA
530,000
1,030,800
557,600
2,010,000
NA
1,087,800
2,080,000
420,000
200,000
287,500
700,000
8,400
622,000
166,000
16,030
30,470
17,690
NA
44,600
NA
NA
NA
NA
141,200
44,600
NA
76,000
NA
750,000
671,500
131,300
qhout other
3.5.4 Tradeoffs
When one chemical is being considered as a substitute
for another, the textile mill must be aware of the potential
for substituting one pollutant, or one pollution problem,
for another. A good example is in the use of surfactants.
Lower BOD-type surfactants, while reducing dissolved
oxygen demand, can pass through treatment and con-
tribute to aquatic toxicity (see Section 4.4, "Chemical
Specialties"). Mills should have personnel experienced
in chemical evaluation because all aspects of a substi-
tution must be considered. The goal of identifying the
alternative that produces the greatest net environmental
gain can become complex in some cases.
3.5.5 Phosphates
Phosphate substitution illustrates the tradeoff issues
that can arise and highlights the need for experts to
assist in evaluations. Phosphates are a common prob-
lem for mills that discharge into nutrient-sensitive receiv-
ing waters. One dyer in eastern North Carolina, for
example, was treating 'wastewater and discharging it
into a nutrient-sensitive stream. To reduce phosphate
discharges, the dyer evaluated two options: 1) install
expensive phosphate removal treatment equipment or
2) reduce phosphorus discharged into the wastewater
through pollution prevention measures (38). Several
nonphosphorus chemical substitutions, shown in Table
3-12, were made without adverse effects on production
or quality. Phosphorus concentrations in treated effluent
decreased from 7.7 ppm to less than 1 ppm (38).
In other cases, alternatives for phosphates can lead to
different types of pollution problems, necessitating an
evaluation of which alternative is the least damaging.
For example, substituting acetic acid for monosodium
phosphate (MSP) lowers the phosphate nutrient content
of wastewater but simultaneously increases the BOD
Table 3-12. Available Substitutions for Phosphates (27, 38)
Phosphate Use Substitute(s)
MSPa Acid salt, pH Acetic acid
TSPPb Water conditioner Soda ash
Phosphoric acid Strong acid Hydrochloric acid
TSPC Alkali builder Caustic, soda ash
Hexaphos Water conditioner EDTA,d silicate
Phosphate surfactants Scouring Ethoxylates, amines
Phosphates Flame retardants Varies
Phosphonamides Flame retardants Varies
a MSP = monosodium phosphate.
TRPP = tetrasnHh im nnlvnhnsnhato
parts of this document in process-specific settings (see
Chapter 4).
0 TSP = trisodium phosphate.
EDTA = ethylene diamine triacetic acid.
92
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and acidity. In considering such a substitution, the textile
mill must examine the site-specific conditions (i.e., the
ability of the local waste treatment system to degrade BOD
compared with the nutrient sensitivity of the receiving wa-
ters). A mill (in consultation with regulatory authorities, as
the case may be) must decide which problem takes the
higher priority. In many cases, one must consider not only
reducing the amount of chemical pollutant in the wastewa-
ter but also improving the waste stream in other ways (i.e.,
treatability, hazardous characteristics, eutrophication po-
tential, dispersabilty, volatility, aquatic toxicity, inhibition of
waste treatment processes). Of course, mechanical alter-
natives can often eliminate pollution altogether and should
not be neglected.
In the example cited above, BOD and pH are generally
easier to treat than phosphates, and the wastewater with
acetic acid can be handled more easily by most treat-
ment systems. In this case, the substitution produced a
"better" waste stream compared with the original, phos-
phate-rich discharge. In other circumstances, however,
substitution may produce a negative effect.
3.5.6 Biological Oxygen Demand and
Chemical Oxygen Demand
The majority of the BOD and COD load from mills is
often attributed to a small number (6 to 8) of chemical
products used (39). The major sources can be identified
by considering the amount of BOD and COD discharged
and the COD or BOD of each individual chemical (39).
The amount discharged is estimated from the amount
used and the fixation percentage (i.e., what fraction
actually becomes part of the fabric) (39). Dyeing chemi-
cals, warp size, knitting oil, and fiber finishes contribute
most of the BOD and COD (26).
Publicly owned treatment works (POTW) sewer sur-
charges for direct dischargers usually are computed
using a formula involving BOD and COD concentrations.
Although BOD and COD are readily treated by the
POTW and are not a major environmental concern (in
the way that metals might be), they do affect the mill
from an economic standpoint and should be addressed
as part of the pollution prevention program.
The formulas used to compute POTW charges give mills
an incentive to reduce BOD and COD in their waste
streams. Much BOD and COD comes from wasted
chemicals (batch dumps), starch size, knitting oils, and
biodegradable surfactants (as discussed in other sec-
tions of this manual); these problems should be ad-
dressed because they impose two types of costs (raw
material loss and sewer charges). Other actions taken
to reduce BOD and COD may be economically produc-
tive but environmentally inferior. Chemical substitutions
that reduce BOD while increasing toxicity or metals
concentration, for example, should be carefully exam-
ined (see Section 4.4, "Chemical Specialties"). All sub-
stitutes for high BOD/COD chemicals should be evalu-
ated to determine what, if any, environmental problems
they present.
3.5.7 Solvents
Several examples of substitutions involving solvents are
discussed in Section 2.2.3, 'Toxic Air Emissions." A few
examples will be presented here to illustrate methods
for applying pollution prevention and substitution to sol-
vent emissions problems.
Organic solvents are widely used in textile processing,
either as emulsions in water or in their natural form (27).
Typical solvent emulsions include scouring agents and
dye carriers for synthetic fibers, especially polyester.
These materials typically exhaust into the fiber and later
are evolved from dryers as airborne VOCs. Examples of
such materials include methyl naphthalene, trichlo-
robenzene, chlorotoluene, ortho dichlorobenzene, per-
chloroethylene, methyl ester of cresotinic acid, butyl
benzoate, and biphenyl (27).
In addition to being emitted to the atmosphere, volatile
solvents can become part of the wastewater stream
through spills, leaks, cleanup (drums, tanks), batch
chemical dumps, and poor housekeeping. The waste-
water treatment process often strips these volatiles from
the wastewater and releases them to the atmosphere.
In scouring, nonchlorinated materials can replace more ob-
jectionable chlorinated materials. One example is substitut-
ing xylene for chlorotoluene (27). Substitutes are also
available for nonaqueous solvents. These are frequently
used as machine cleaners, parts degreasers, and in labora-
tory applications (e.g., for extraction procedures) (35).
Wasted solvents such as machine cleaners and degreasers
can be reduced by using a device such as the one shown
in Figure 3-4 or by using substitutes. Laboratory or machine-
cleaning solvents should never be disposed of in a sanitary
sewer. Instead, solvent recovery bottles should be available
for later pickup and proper disposal. Keeping different types
of solvents separate is usually economically advantageous
because disposal and recovery methods vary. At a mini-
mum, separate waste containers should be available for
chlorinated solvents, nonchlorinated solvents, and water-
free oils. The use of chlorinated solvents in the laboratory
should be minimized, particularly by substituting Freon,
xylene, or toluene for chlorinated solvents (e.g., methylene
chloride, perchloroethylene, chloroform) or by substituting
less-toxic or less-hazardous solvents (e.g., xylene or tolu-
ene) for benzene (35).
In several case histories, solvent substitutions have pro-
duced outstanding pollution prevention results. Wood
and Bishop reported that Du Port's division for organic
chemicals, plastics and synthetic fibers substituted less
offensive materials for priority pollutants such as
methylene chloride, chloroform, and toluene in many
93
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Overflow
Una
Bowl
Screen
Pump To
Raise
and Lower
Solvent
Solvent Reservoir
Flgura 3-4. Schematic of a small parts cleaning system.
applications (23). Morris reported that one company
applied 70 percent of coatings using solvent systems,
and the substitution of aqueous systems reduced this to
30 percent (2).
3.6 High-Extraction, Low-Carryover
Process Step Separations
Textile operations often expose substrates to a process-
ing solution, all or part of which is subsequently re-
moved. The amount of solution the substrate retains is
called wet pickup (WPU). When several wet steps follow
each other in succession, mills commonly dry the fabric
between each step. This minimizes carryover and down-
stream contamination, and ensures even pickup of the
subsequent processing solution.
Sometimes, drying the fabric between each step can be
avoided, saving energy (gas or steam), associated air
emissions, and boiler ash (a solid waste). Mechanical
extraction of water is possible to achieve fairly low WPU
(e.g., 25 percent to 50 percent). Minimizing WPU can
often reduce downstream processing bath contamina-
tion, which helps avoid fouling of machines and reduces
the need for cleanup activities. Typically, continuous
processes work this way, and often batch processes do
as well. Several reasons exist for minimizing WPU:
• To control the exact amount of processing bath on
the substrate to produce a desired result (i.e., to limit
WPU to a minimum level for energy efficiency).
• To minimize, control, or equalize the moisture content
of substrate before it goes into another process, such
as wet-on-wet dyeing or finishing, or a drying operation.
• To recover the processing mix material and prevent
it from carrying over into downstream processing so-
lutions (i.e., to prevent carryover).
• To recover the processing mix material and prevent
it from escaping into the environment (i.e., to elimi-
nate dragout).
Several applications of this technique are presented in
other sections of this document (see Sections 2.2.7,
"Water Conservation," and 4.12, "Finishing").
For finishing or continuous dyeing, a substrate is satu-
rated (usually by immersion) with a processing bath.
Excess amounts are removed to the bath to achieve a
controlled add-on level. This is called saturation/expres-
sion. The other option for controlling add-on is to use
sprays, foams, and kiss rolls (see Section 4.12, "Finish-
ing"). The amount of material added on in the wet state
is expressed in terms of WPU:
WPU =
mass of solution sorbed
mass of dry substrate before treatment
(Eq. 3-1)
Typical WPU values for saturation/expression proc-
esses on previously dry fabric are shown in Table 3-13.
As the table shows, the use of high-extraction methods
can reduce the amount of dragout or carryover by up to
one-half.
Table 3-13. Typical WPU Values for Saturation Expression
Processes on Previously Dry Fabric
WPU Typically Achieved
Type of Substrate
Conventional
High Extraction3
Cotton
Synthetic
90%-130%
25%-85%
45%
25%
Minimum required to thoroughly wet substrate, depending on sub-
strate structure.
The substrate generally responds to the amount of
chemical add-on, not the WPU. To describe this, the
term dry add-on is used. Dry add-on is:
mass of dry chemical
Drvadd-on= solids added on (Eq. 3-2)
mass of substrate before treatment
A third parameter is the mix concentration, which is:
mass of solids in the mix (Eq. 3-3)
Concentration =
mass of chemical mix total
The relation between the WPU, dry add-on, and concen-
tration is:
Dry add-on = concentration * WPU (Eq. 3-4)
When the WPU of a process changes, the mix concen-
tration must be adjusted to achieve the same dry add-
on, thus the same end result on the fabric. For example,
a resin might be applied conventionally at 10 percent
94
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concentration and 110 percent WPU, giving 11 percent
dry add-on. If a low add-on method were used, with 45
percent WPU, then the required mix concentration
would be:
Dry add-on = concentration * WPU (Eq. 3-5)
0.11 = concentration * 0.45
Concentration = (0.11/0.45) = 0.244
or about 25 percent
3.6.1 Wet Pickup Minimization
Minimizing the exact amount of processing bath picked
up by the substrate to produce a desired result has
several benefits. Less energy is used to dry the water,
and chemicals are used more efficiently in the low add-
on process because of less thermal migration in the
drying stage. High-extraction (or low add-on) devices
are used to achieve the minimum WPU and evenness
required for dyeing and finishing. These devices are
described in Sections 2.2.7, "Water Conservation," and
4.12, "Finishing."
3.6.2 Wet-on-Wet Processing
Normal practice, as indicated above, is to apply finishes
(or dyes in continuous dyeing) to dry fabric. If the sub-
strate comes directly from a previous wet state, how-
ever, a drying step can be eliminated by using a
wet-on-wet process in which the substrate is treated to
ensure a very low and even moisture content. Finish can
then be applied at a higher WPU, thus giving add-on of
finishing chemicals (see Figure 3-5).
During this process the water in the incoming substrate
tends to dilute the finish mix. This often necessitates a
control system to sense and adjust the chemical feed to
the finish mix saturator. The process; does not work
without a high-extraction, low-carryover separation of
the water saturator from the finish saturator. Also, the
process tends to be uneven if the water saturator step
is not performed properly because the water settles out
in the storage boxes, resulting in very uneven finish, dry
add-on and uneven fabric performance.
In addition to the wet-on-wet finishing example cited
above, the same technique can be used for dyeing some
styles, notably toweling. In these applications, the cost
and energy savings are attractive because toweling by
its nature retains high levels of moisture and is therefore
expensive to dry. The toweling is desized, scoured, and
bleached, then wet out and extracted with a high-extrac-
tion device, followed by wet-on-wet dye application in a
continuous range.
3.6.3 Process Step Separations
Maintaining good isolation between incompatible mixes
in sequential process steps is crucial to achieving long
runs out of process solutions without having to stop off
for cleanup and refurbishing processing baths (with as-
sociated discards). Often, continuous dye application in-
volves a sequence of chemically incompatible steps. The
sequence for vat dyes, for example, is shown below:
• Reduce vat dye in a holding tank (or use prereduced dye).
• Pad substrate with reduced vat (reducing bath)i
• Apply steam to the substrate for penetration.
• Wash off unpenetrated surface dye and residual re-
ducing agent.
• Perform high-extraction/low-carryover step, separation.
• Oxidize vat dye within the fiber (oxidizing bath).
• Wash. '
• Dry. : . . -
Any carryover of reducing agents into the.oxidizing bath
produces contamination that degrades the quality of the
process and requires the addition of more oxidizerto the
mix. Similar situations exist with naphthol and sulfur
dyes, where separations are required for various rea-
sons. In other processes, incompatible pH or other situ-
Fabric
WPU
Water Wet-Out Saturator
Figure 3-5. Wet-on-wet processing to eliminate drying stage.
Normal
Extraction
(Padder)
Finish Bath Separator
95
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ations may exist. For example, residual alkalinity from
mercerizing can cause premature reaction of fiber-
reactive dyes in continuous dyeing. The high-extraction
device, when used as described above, prevents con-
tamination of the oxidizing bath with reducing agents
and prevents dilution of the bath with washwater.
3.6.4 Recovery of Offensive Materials
Several textile processes, notably mothproofing of wool,
are based on offensive materials such as permethrin. In
such processes, material recovery of as much dragout
as possible is integral to environmental protection.
Recovery of dragout for batch process mothproofing of
wool is done with a specially adapted centrifugal extrac-
tor, as explained in Section 4.12, "Finishing." This con-
cept applies in general to applications of materials
followed by washing processes. The higher the me-
chanical extraction of materials, the less washoff dis-
charged to the environment.
3.6.5 High-Extraction/Low-Add-On Devices
Many different versions of low add-on or high-extraction
devices exist, as listed below (40):
• Centrifugal extractors
• Curved blade applicator
• Engraved rollers
• Fabric transport loops
• Gas-phase finishing
• High-extraction pads
• Kiss rolls
• Mach nozzles
• Sprays
• Stable foams
• Unstable foams
• Vacuum extractors
At ITMA 1987 and 1991, many new high-extraction de-
vices and low add-on systems were shown (8, 41).
Some of the more noteworthy were vacuum systems
and centrifugal extractors. Vacuum technology reduces
dragout and carryover of process solutions from step to
step, thus avoiding process efficiency losses because of
downstream bath contamination. This reduces chemical
use, cleaning frequency, bath discards, and machine
cleaning, and is particularly effective at improving wash-
ing efficiencies. Several companies showed innovative
centrifugal extractors with interchangeable baskets.
These are very flexible and efficient in moisture removal
from yam packages, fabrics and garments. (8).
3.7 Incoming Raw Material Quality
Control
In discussing pollution prevention programs, most ex-
perts raise the issue of incoming raw material quality
control (QC) (15, 26-28, 42-45). QC of incoming raw
materials seems obvious and simple, but textile mills
rarely, if ever, practice proper raw material QC techniques.
One important fact to realize is that the most frequently
touted techniques for pollution prevention (i.e., right-
first-time production and process optimization) depend
completely on raw material consistency as a foundation.
Without a uniform, consistent raw material input, con-
stant process adjustments and changes must be made
in a never ending (and never successful) quest for
optimization.
Figure 3-6 lists incoming raw materials that should un-
dergo QC testing. They are ranked roughly according to
typical testing frequency. Interestingly, some of the high-
est volume raw materials (e.g., commodity chemicals,
synthetic fibers) are the least tested, along with often
highly toxic maintenance and cleaning chemicals.
Most Often Tested
Yarns
Fabric
Natural Fibers
Water
Dyes
Specialty Chemicals
Commodity Chemicals
Synthetic Fibers
Utilities (e.g., Air, Steam, Electric, Fuels)
Maintenance and Cleaning Chemicals
Least Often Tested
Figure 3-6. Incoming raw materials that should undergo QC
testing.
Raw material testing procedures vary greatly according
to the type of raw material. For example, tests of com-
modities by titration are appropriate for process perform-
ance but not for detecting environmental problems.
Trace impurities in raw materials (e.g., synthetic fiber
finishes), which standard tests cannot detect, can cause
substantial pollution problems. These should be sepa-
rately tested using an appropriate test protocol. Detailed
testing procedures for these raw materials are given in
Sections 3.16, "Consumer, Installer, and End-User Infor-
mation," 4.2, "Fibers," 4.4, "Chemical Specialties," and
4.5, "Chemical Commodities."
The groundwork for successful implementation of an
incoming raw material QC program must be laid in two
areas: (1) prescreening raw materials before use (26)
96
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and (2) establishing specific and appropriate purchas-
ing, packaging, and inventory control policies to prevent
the ordering and use of untested materials (43).
Standardized testing and reporting procedures are im-
portant (46), as is a review of all test results by customer
and supplier, even when no problem is apparent. This is
necessary to establish a baseline and a protocol for
dealing with future difficulties (see Section 4.17, "Glo-
balization of Pollution Prevention").
A good example of the value of testing for impurities is
cited in a study by Holme (44). The study covered 70
percent of woolen mills in the United Kingdom, both
large and small. Pentachlorophenol (PCP), a harmful
agricultural residue in wool, was detected in wastewater
from finishing plants. Researchers determined that it
originated in the incoming greige goods. The presence
of PCP in wastewater decreased by 50 percent after
companies specified, as a part of their purchasing poli-
cies, that they would not accept PGP-containing greige
goods for finishing. No acceptable treatment technology
is known for PCP, so this pollution prevention strategy
was the only method of environmental protection (44).
3.8 Maintenance, Cleaning, and
Nonprocess Chemical Control
Chemicals used for maintenance and cleaning are often
among the most toxic, offensive materials found in tex-
tile mills (15, 26). Many mills that have otherwise good
pollution prevention programs overlook these chemi-
cals, however. Because the chemicals are not used
directly in production processes, they often escape the
rigorous evaluation and prescreening that production
chemicals must undergo (27).
In addition, mills usually do not specify procedures for
using maintenance and cleaning chemicals nearly to the
extent that they do for production chemicals. For exam-
ple, the frequency, amount, and manner of use for ma-
chine cleaners, facility cleaning agents, and other shop
chemicals are rarely as well documented (if at all) as
chemicals used in production processes. Further, shop
employees often are not trained in chemical handling to
the same extent as process operators. All of this leads
to a substantial potential for environmental problems
related to maintenance and cleaning chemicals.
Typical examples of chemicals used in maintenance and
cleaning operations are:
• Acid-based parts cleaners.
• Adhesives.
• Biocides for air washers.
• Boiler chemicals.
• Lubricants.
• Paints.
• Solvent-based materials (e.g., paint strippers, floor
cleaners).
« Weed killers used around bulk storage tanks.
Mills can minimize the potential environmental impacts
from these materials in several ways, the first of which
is to treat maintenance chemicals the same way as all
other chemicals in a facility. The procedures used to
monitor and control these chemicals should include:
• Prescreening
• Incoming chemical quality control
• Worker training
• Procedures for use
• Disposal of obsolete chemicals
• Inventory control
• Packaging
• Purchasing specifications
3.8.1 Solvents
Solvents are a frequently misused class of shop chemi-
cals. Waste solvents originate from all types of machine
cleaning and shop activities, as well as from print screen
cleaning. Simple control methods can often be effective.
A useful system for small parts cleaning consists of
mounting a bowl on top of a delivery tube, which in turn
is positioned above a reservoir as shown in Figure 3-4
(27). When needed, solvent is pumped into the bowl
where small parts to be cleaned are placed. A screen
prevents the parts from falling down the tube and into
the reservoir. After use, the solvent flows back down into
the reservoir by gravity. This device can also be used to
wet rags with solvent for cleaning. Both uses of this
system avoid the need to dispose of leftover solvent that
has been poured into a separate container for use.
Contaminated solvent, whether from parts or machine
cleaners, or from processing uses such as solvent
scouring ranges or dry cleaning, can be recovered by
distillation. Sludges, residues, and still bottoms not re-
covered should be kept separate from other wastes and
disposed of separately. In some cases, these may have
commercial value (e.g., lanolin from wool dry cleaning).
3.9 Developing Markets for Wastes
The textile industry has benefited from the estab-
lishment of formal and informal networks for exchanging
certain types of wastes. In these waste exchanges, two
or more organizations develop a mutually beneficial re-
lationship whereby materials that would otherwise be
thrown away are made available to organizations that
97
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can use them. Waste exchanges redirect materials back
into the manufacturing or reuse process by matching
generators of specific wastes with companies that can
use those wastes as manufacturing inputs. This not only
helps to extend the lives of products and supplies but
also reduces purchasing and waste disposal costs.
Benefits of waste exchanges include:
• Reduced waste disposal costs
• Savings in material and supply costs
• Savings from more efficient work practices
• Revenues from marketing reusable materials
Waste exchanges are one of the simplest, most inex-
pensive waste prevention strategies a company can
implement. The first step toward implementing a waste
exchange program is to conduct a companywide inven-
tory of potentially reusable products and supplies. In
addition, employees often have good suggestions about
materials that can be reused, so their opinions should
be solicited.
Most state offices of waste reduction can supply infor-
mation and lists of recyclers who will buy waste prod-
ucts, provide information on existing active and passive
waste exchanges, and supply details and guidance on
how to establish a waste exchange. In some places,
computer- and catalog-based networks have been es-
tablished to help match up companies who wish to
participate in exchanging their materials.
In the textile industry, scraps, fibers, rags, and other
materials are routinely sold to other mills or to recyclers.
Other materials may also have potential scrap or reuse
value. Table 3-14 contains a partial list of waste materi-
als that can be exchanged.
3.10 Process Alternatives
New, cleaner technologies and process alternatives can
simultaneously reduce pollution and cut processing
costs (2). Equipment manufacturers, responding to
changing environmental priorities, are offering equip-
ment (e.g., dyeing machines) that is more energy efficient,
features reduced water consumption, accommodates re-
covery and recycle of waste streams, and allows for
more precise control over operating parameters, an im-
portant factor in preventing pollution.
Various sections of this document describe specific
process alternatives that are inherently less polluting.
Table 3-15 lists some conventional processes along with
cleaner technology alternatives. The table also points to
sections in this document that discuss such equipment.
The sections below describe cleaner alternatives for
specific production processes.
Table 3-14. Examples of Textile Industry Waste Materials
That Can Be Exchanged
Aluminum
Batteries
Brass
Cardb9ard
Chlorinated solvents
Cloth scraps
Cones (paper yarn cones)
Copper
Corrosive liquids
Cotton
Cutting oil
Fibers
Fuel oil
Glass
High-density polyethylene
Hydraulic oil
Inks
Iron
Lead
Metallic sludges
Motor oil
Office paper
Oil/water mixtures
Organic solvents
Paints
Pallets
Paper tubes
Plastic
Polymer scrap
Polypropylene
Polystyrene
PVC
Rags
Rubber
Seam cutouts
Selvage trimmings
Solvents
Steel
Steel drums
Tin
Tires
Urethane materials
Wood scraps
Wool
Yarn
Zinc
3.10.1 Improved Coatings Systems
Solvent-based coating systems are the largest produc-
ers of hazardous air pollutants like methyl ethyl ketone
(MEK), toluene, and acetone from textile operations
(47). Air testing, sampling, analysis, and treatment for
these pollutants are very difficult and expensive, so
pollution prevention is an attractive alternative to con-
trolling these emissions (48). One alternative is to use
water-based systems in place of solvent-based systems
wherever possible (2). In addition, solventless coating
systems have the potential to substantially reduce VOCs.
Wilkinson (49) describes an approach based on powder
coating technology. Since synthetic polymers became
available in the 1940s, coated products, including
coated textiles, have been in high demand by consum-
ers. Typical products include high-technology coated
and laminated fabrics, waterproof laminates, fire-retar-
dant backcoated upholstery and drapery, and tennis
shoe uppers. Also, many industrial fabrics, such as con-
veyer belts, tarpaulins, and offset printing blankets, are
made with this technology. Conventional systems use
latex or other synthetic polymers in an organic solvent
medium. This is sprayed on the cloth, and the solvent
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Table 3-15. Process Alternatives That Can Reduce Pollution
"Normal"
Process
Chemical handling
Control
Dye handling
Dyeing
Finishing
General
Knit dyeing
Padding
Print screen
making
Printing
Reactive dyeing
Washing
Waste discharge
Pollution Prevention
Alternative
Automatic chemical systems
IBCs vs. drum chemical
handling
Bulk chemical storage
Adaptive/improved control
Automated color kitchen
Dye class alternatives
Dyebath reuse
Continuous vs. batch dyeing
ULLR dyeing
Foam finishing
Mechanical finishing
Low add-on finishing
Spray finishing
Bath reuse
Knit dye ranges (continuous)
High-extraction systems
Vacuum extractors
Laser screen making
Ink-jet printing
Transfer printing
Pad batch dyeing
Countercurrent washing
Recovery systems
Section(s)
4.12, 4.18
1.2,2.2,
3.11,4.4
4.5
2.1,3.19
3.18, 3.19,
4.10
4.3, 4.10
3.19, 4.10
4.10
3.19, 4.10
4.12
4.12
4.12
4.12
2.2, 3.19,
4.9, 4.10
3.19
3.6
3.19
3.19, 4.11
4.11
4.11
4.10
3.19, 4.9
3.19
evaporates, leaving the latex or polymer coating. This
process releases undesirable VOCs to the atmosphere.
Powder coating can substitute for waterless systems,
producing the same end results as solvent-based coat-
ings but with less pollution. Wilkinson used three appli-
cation methods: 1) powder scatter, 2) paste point (see
Figure 3-7), and 3) engraved rollers.
This is an emerging technology, based on the desire for
a waterless, solventless coating system. NCSU has
conducted similar experiments, in which thermoreactive
epoxide materials (i.e., powder paints) or thermoplastic
xerographic materials have been used for solid dye
shades as well as for fabric printing. Undesirable VOCs
from coating operations, including MEK, xylene, tolu-
ene, and acetone, are completely eliminated.
3.10.2 "Cold" Processes
The textile industry provides many opportunities for fur-
ther application of cold batch processes, similar to those
used for pad-batch dyeing (see Section 4.10, "Dyeing").
In these processes, the processing solution is applied to
the textiles with a pad. The textiles are then wound on
t t t t T f.
1507C-2607C
1507C-2607C
457C-607C
Figure 3-7. Schematic of (A) powder coating scatter, (B) paste
point coating, and (C) powder paint coating using
gravure roller (49).
99
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rolls or batched in boxes, bins, or kiers for extended
periods, ranging from 4 to 24 hours. Bleaching, desizing,
resin finishing, and some types of dyeing can be done
this way. The benefits usually take the form of energy
savings (i.e., less steam use) and reduced boiler emis-
sions. One example of an energy-saving dyeing process
that some mills have adopted is low-temperature dyeing
of nylon (50). This requires different dyeing assistants
than the normal dyeing process.
3.11 Optimized Chemical Handling
Practices
One of the most fundamental elements of any pollution
prevention plan in the textile industry is optimization of
chemical handling (15,27,43). Proper chemical handling
procedures ensure that the right chemicals are used,
that they are used in the correct amounts, that they are
used in such a way as to minimize the amount of unre-
acted chemical that enters the waste stream, and that
all wastes from processes involving chemicals are prop-
erly handled.
Good chemical handling does not occur by accident; it
results from many preliminary planning steps, including:
• Attention to purchasing specifications.
• Packaging requirements.
• Chemical receiving, storage, and mixing.
• Proper worker training.
• Engineering controls such as automated chemical
handling.
These planning steps are described in greater detail below.
3.11.1 Purchasing
Proper chemical handling begins with the establishment
of procedures for ordering and purchasing chemicals.
Vendors must be made partners in the pollution preven-
tion program. During the prescreening and evaluation
process for new chemicals, specifications and agree-
ments between the vendor and the user must include
details such as packaging, chemical constitution, and
control of impurities. Appropriate methods for controlling
incoming chemical quality must be formulated, based on
the type of chemical, prescreening data available, and
other factors.
In addition, open and regular lines of communication
with the vendor must be established to report the results
of QC tests. This serves the dual purpose of letting the
vendor know that the chemicals are being tested and
establishing the vendor's acceptance of the QC tests. If
vendors are involved in establishing QC test protocols,
they will have difficulty citing problems with the testing
procedures as the basis for disputing any future quality
problems.
3.11.2 Packaging
Textile operations commonly use several types of pack-
aging, including:
• Bulk containers
• IBCs
• Drums
• Bags
The manner of packaging is important to reducing pol-
lution and waste resulting from chemical handling.
Chemicals should be purchased, handled, and trans-
ported in containers that are designed to minimize spills
(15). In most cases, bulk containers or IBCs provide the
best pollution prevention potential. Bagged chemicals
and, to a lesser extent, drums are particularly suscepti-
ble to damage and spills (43).
If a spill occurs, the spilled material must not be washed
down the drain but instead should be captured in wet/dry
vacuum systems (15,27,43, 51). Further information on
this subject is included in Sections 4.4, "Chemical Spe-
cialties," and 4.5, "Chemical Commodities."
3.11.3 Receiving
At least two people should receive each chemical ship-
ment. This is especially important in bulk chemical de-
liveries, which can present serious problems if a
problem arises during off-loading. For example, a simple
problem such as a defective fitting can result in chemi-
cals being sprayed on an operator or large amounts of
chemicals being released. In addition, spills can gener-
ate a large amount of contaminated soil, which may
require handling as hazardous waste, with associated
expenses and liabilities. Every receiving area should be
equipped with safety devices such as a shower, eye-
wash, and spill-absorbent material.
3.11.4 Storage
Chemicals should be stored according to manufacturers'
recommendations and segregated according to type
(e.g., oxidizer, reducer, acid, alkali, flammable). Bagged
chemicals and other breakable types of packaging
should be avoided. If they are used, they should be stored
in well-protected areas. In particular, storage near high
traffic areas should be avoided entirely, especially for
bagged commodities such as salt and soda ash (15).
The facility design should include proper racks or other
storage bins. Bulk tanks should have proper dikes,
berms, or other spill containment mechanisms. Pallets
of bags or drums should never be stacked on top of each
other. In addition, forklifts should be properly equipped
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to handle each type of packaging. Extremely hazardous
or offensive chemicals should be identified to ware-
house handlers.
Shipping, storage, handling, and delivery systems
should be optimized to reduce spill potential and auto-
mated to improve dosing accuracy (51). Storage areas
should not have floor drains (15), but instead should have
capabilities for dry capture (e.g., vacuum system). Recov-
ered spilled material should be reclaimed if possible or
segregated for separate treatment and disposal (51).
Storage areas should be regularly inventoried for obso-
lete chemicals. If proper receiving procedures are fol-
lowed, the date of receipt and incoming QC testing will
be marked on each container. From that mark, inventory
personnel can determine the age of each item. Minimiz-
ing surplus chemicals reduces the potential for obsolete
chemicals to become hazardous wastes (43).
3.11.5 Mixing
All chemicals (process and nonprocess) should be ac-
curately weighed, dispensed, and mixed in such a fash-
ion as to avoid spills. Using the scoop or "dipperful"
method of measuring has minor economic conse-
quences but potentially major pollution consequences
(15). Automatic metering and mixing systems ensure
that mix recipes are always accurately prepared. This is
vitally important because it enables the mill to experi-
ment with different mix ratios and varying chemical
quantities to assess the impact of changes in chemical
use on product performance and pollution generation.
The issue of proper scales and accurate calibration is
discussed in Section 4.18, "Support Work Areas."
Scales should be adequate for the purposes intended
and regularly calibrated to ensure accuracy.
Moore (42) reports a case history in which a mill that
processed nylon pantyhose was not in compliance with
a city pretreatment ordinance on BOD, COD, and zinc.
In the process of improving work practices, systems
were introduced for accurately weighing all chemicals,
as opposed to the previous practice of using a "dipper-
ful" or "bucketful" (i.e., volumetric approximations). A
zinc stripping agent was also eliminated from the chemi-
cal inventory. The result was complete} compliance on
all parameters.
All process equipment, including dyeing machines and
mix tanks, should have fill levels marked for correct
volume. Metering pumps should be calibrated, precise
feed rates should be established for all processes, and
workers should be trained to follow these process speci-
fications. Instructions to employees must be precise,
and employees must understand how to follow them.
Also, proper equipment must be available to handle
chemicals. A formal training program with regular re-
fresher training is necessary to ensure success in
chemical measuring, mixing, and handling. Having one
employee train the next is not acceptable because this
practice tends to encourage the passing on of bad habits
from one generation of employees to the next (15).
Poor shade repeats are a major cause of economic loss
and pollution in dyeing operations. On average, employ-
ees in a drug room or color kitchen make 300 weighings
per day. Errors may arise from many sources, including
sorption of moisture from the atmosphere, which may
amount to a maximum of 20 percent error in dye weight
(52).4 Dry dispensing systems for powder dyes are avail-
able that are quick, easy, and accurate (see Figure 3-8).
These systems feature storage compartments, valves,
weighing devices, and mechanical parts that are ex-
tremely resistant to corrosion and easy to clean. Preci-
sion of 0.01 gram on a 10- kilogram delivery is available,
and the accuracy is within 1 percent. The system also
includes hard automated container transport to and from
the dispensing area (52).
If color is inaccurately dispensed, corrective additions
must be made to the dyeing. This can not only increase
the color use but also decrease color exhaust; require
additional time, chemicals, and energy; and, in some
cases, require stripping and redyeing. This is the costli-
est error of all in terms of economics and pollution.
Inaccurate weighings are much worse in the drug room
because steam and moisture are present, in addition to
the abuse that production dye weighing scales receive
compared with research laboratory scales. The manner
of calibration and use of scales in weighing essential
process chemicals deserves much closer attention.
Pasting procedures for dyes are not obvious and can
significantly affect the quality of the work produced by
the dyehouse. Each dye class has a specific pasteup
procedure that must be followed for optimum results.
Dye vendors readily supply proper pasteup procedures
for specific dyes.
3.11.6 Worker Training, Expertise, and
Attitudes
One vital piece of information that workers should be
made aware of is which chemicals in that worker's area
are potentially most harmful to the environment (e.g.,
metal-bearing dyes). The worker must be trained to be
cautious about using these chemicals. Also, training
must include correct procedures for pasting, dissolving,
or emulsifying chemicals. These procedures should also
be subject to closer auditing and recordkeeping.
3.11.7 Automated Chemical Systems
Perhaps the most significant pollution prevention
achievement in textile equipment during the last 10
4 Errors average about 4 percent.
101
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Vibrascrew Dispense System
'•> ffV'f''TT^r^' JT''' •' "ft yyj
Pneumatic Vibrating Mechanism
Dispense and Weigh Scale Setup
Vibrascrew Dispense Valve
Dust Extraction Hood
Dust Extract
Bucket
Scale
Pneumatic
Figure 3-8. Vibrascrew dispense system (52).
years has been the introduction of automated color
kitchens, bulk chemical systems, and dosing systems
(see Sections 3.18.1, "Automated Mix Kitchens," 3.19,
"New Equipment," and 4.11, "Printing"). These new sys-
tems not only reduce working losses from implement
cleanup and disorderly work practices but also ensure
that the exact amount of mix is made, reducing discards.
These systems are particularly beneficial to continuous
dyeing operations, printing, and finishing. By reducing
startup and stopoff waste, they also make shorter runs
on continuous equipment more economically feasible. A
companion piece of equipment is the programmable
dosing system, which can increase process efficiency
greatly (27).
Computerized dispensing equipment cuts color waste
and pollution (53). These systems integrate the func-
tions of color computation (determining the exact
amounts needed for the lot), color dispensing (measur-
ing out each component of the mix or print paste), and
delivery to the dyeing or printing machine (with robot-
ics/hard automation). At least one carpet printing and
dyeing company has integrated the function of a com-
puterized dispensing machine with several other parts
of the automated dyehouse control (weighing, reuse of
recovered color) (53). Color reuse is done via a specially
designed color reuse holding system.
3.12 Raw Material Prescreening
(Before Use)
Chemical prescreening is widely recognized as an effec-
tive method for eliminating hazardous and offensive
materials before they get into production processes (15,
17, 27, 43, 54). The purpose of prescreening is to
determine:
• Chemical and mechanical alternatives.
• Proper use of the chemical.
• Proper training and equipment required for use.
• Incoming raw material QC test methods to be used
and nominal values.
• Proper disposal and treatment methods.
• Potential environmental impacts.
3.12.1 Types of Chemicals
Textile chemicals may be classified into two categories:
1) commodities and 2) specialties. Commodity chemi-
cals generally consist of known materials and are based
on at least one relatively pure chemical substance. Spe-
cialties are proprietary mixtures of materials whose ex-
act composition may not be known to the customer.
3.12.1.1 Commodities
Commodities used in textile mills include a wide variety
of acids, alkalis, and oxidizing and reducing agents.
Because these materials are of a known composition,
prescreening is relatively straightforward. Prescreening
of chemical commodities should be used to determine:
• Interactions with processes and substrates
• Reactions/interactions with other chemicals
• Recommended handling and application procedures
• Environmental effects
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Because the materials are relatively pure and of known
composition, the reactions and interactions are easy to
gauge and the pollution characteristics are fairly well
known. Therefore, mills have little difficulty establishing
procedures for handling and for incoming raw material
QC (see also Section 4.5, "Chemical Commodities").
3.12.1.2 Specialties
Unlike commodities, the composition of specialty chemi-
cals may be unknown to the customer, and specialties
are almost always mixtures of different chemicals. Thus,
mills have difficulty determining the reactions and inter-
actions with other, process chemicals and substrates.
The onus, therefore, falls on the vendor to provide infor-
mation and assistance to the customer making the
evaluation. The following is a list of typical evaluation
parameters that mills should ask the vendor to supply:
• Percentage solids
•. Proper manner of storage and handling
• Safety equipment required, including:
- Personal safety equipment
— Facility engineering controls
- Spill control equipment
• Environmental characteristics, such as:
- BOD (5-day and longer term)
- COD
-------
• Legal representative
* Wage hour worker representative
• Purchasing agent
Although not ail facilities employ individuals from each
of these specialties, the list represents the range of skills
and types of input that may be helpful when conducting
prescreening evaluations.
3.12.3 Evaluation Policy
An evaluation should be performed on all chemicals,
including process, maintenance, and cleaning chemi-
cals as well as those brought on site by outside contrac-
tors. Prescreening should be a basic part of a mill's
purchasing policy, inventory control, maintenance op-
erations, housekeeping, production processes, and re-
covery/recycie/reuse programs. Trace impurities in raw
materials should be identified and evaluated, if possible,
because they can adversely affect product performance
and can generate pollution (43).
3.13 Disinformation About Environmental
issues
A major trend of the 1980s and 1990s has been con-
sumer preferences for "environmentally responsible"
products. Manufacturers have responded by changing
their production methods (in cases where their products
were not very "green") and by making claims of environ-
mental superiority for products they felt were produced
in an environmentally superior manner. Recently, a
backlash of criticism has arisen against the way in which
products are evaluated and the way some companies
tout the environmental benefits of their products.
The "environmental friendliness" of textile products has
been the focus of some public discussion. Among the
issues raised are the use of dyes and pigments that are
harmful to the environment and the excessive use of
chemicals for processing and finishing textiles. Some
textile manufacturers have responded by misrepresent-
ing their products with environmental claims developed
through clever advertising and marketing strategies
(47). For example, Mohr (47) cites efforts to promote the
processing of raw cotton ("gray" or "green" cotton) di-
rectly into consumer products when in fact, the raw fiber
is contaminated with natural pollutants that must be
removed by scouring, bleaching, and other chemical-in-
tensive actions to make it suitable for consumer use
(47). Other manufacturers may make use of analytical
tools such as product life cycle analysis in an irrespon-
sible way to back up misleading environmental claims.
Textile manufacturers should be proactive about poten-
tial environmental charges that could be levied against
their products and processes. The most effective strat-
egy is to have in place a highly developed pollution
prevention plan and a high level of expertise and aware-
ness of pollution issues among workers and supervisors.
3.14 Scheduling Dyeing Operations To
Minimize Machine Cleaning
In dyeing operations, startups, stopoffs, and color changes
often result in losses of substrate, potential off-quality
work, and chemically intensive cleanings for machines
and facilities. Scheduling dyeing operations to minimize
machine cleanings can have a considerable impact on
pollution prevention.
Changes required by scheduling activities can generate
significant amounts of waste for the textile mill. Machine
cleaning is a significant contributor because machine
cleaners are among the most toxic and offensive chemicals
used in textile wet processing (15, 55). (For a more
complete discussion of the losses associated with pro-
duction stopoffs and changeovers, see Sections 3.8,
"Maintenance, Cleaning, and Nonprocess Chemical
Control," and 4.10, "Dyeing.") A well-planned dyeing
schedule reduces the number of machine cleanings
required and also the pollution that results from startups,
stopoffs, and color changes.
Ultimately, the need for dye machine cleaning is contin-
gent upon the sequencing of colors in the dyeing proc-
ess. The ideal sequence, requiring the least amount of
machine cleaning, is to run the same color repeatedly
on a particular machine. The second-best dyeing se-
quence is to group colors within families (red, yellow,
blue), then run the dyes within one color family from
lighter to darker values and from brighter to duller chro-
mas. When the darkest, dullest color of the family ,is
reached, a thorough cleanup prepares the machine for
a subsequent light, bright shade. Combining dye lots
and scheduling dyeing production in this way prevents
pollution by minimizing machine cleanings and mix dumps.
For scheduling of dyeing operations to become an ef-
fective pollution prevention measure, schedulers should
understand the environmental impacts of their schedul-
ing decisions. Schedulers are unlikely, however, to be-
come experts on the impacts of scheduling on 1)
process chemical discards, 2) chemical wastes, and 3)
emissions factors of various production processes.
Therefore, schedulers should receive some guidance
making their scheduling decisions. At present, "smart"
scheduling systems that can plan changeovers to mini-
mize machine cleaning are not commercially available
but are under development.6 Once these are on the
market, process engineers and schedulers will have the
opportunity to control pollutants at the production sched-
uling and planning stage.
6Stutz, G., and B. Smith, 1994. Personal communication between
Gene Stutz and Brent Smith, Department of Textile Chemistry, North
Carolina State University, Raleigh, NC.
104
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3.15 Standard Tests, Methods, and
Definitions
One of the greatest needs in improving pollution preven-
tion industrywide is the ability to transfer the successes
of one plant to another and from other industries to the
textile industry. Transfers of pollution prevention ideas
and cleaner technologies produce successful results
and require minimal cost and effort. Standardization of
tests, terminology, and reporting formats is a useful tool
for achieving successful transfer of information. Stand-
ardization also reduces potential disinformation and
misunderstandings about processes and products.
Some areas that should be standardized within a pollu-
tion prevention program, and if possible between pollu-
tion prevention programs, are:
• Audit protocols and reporting.
• Case history protocols and reporting.
• Aquatic toxicity testing and reporting.
• Quantifying treatability, offensiveness, and dispers-
ability.
• Terminology related to biodegradability and other
terms.
• Chemical and process alternative evaluation protocols.
• QC of incoming materials.
Modak reports that many international textile manufac-
turers are using the Austrian Textile Research Insti-
tute/Hohensteiner Institute protocol for substances-
called OTN 100 (24). The tests are carried out by gas
chromatography/mass spectrometry (GC/MS), and the
products are certified as passing the OTN 100 test.
One downfall of standardization is the negative impact
it may have on creative thinking and innovation. If a
pollution prevention audit or evaluation is reduced to an
exercise in following a checklist or filling out a form, then
the program runs the risk of becoming only a superficial
activity with little importance to those involved. This is a
serious matter and is the main reason why pollution
prevention should be a grassroots, site-specific pro-
gram, not a mandated, standardized paperwork exercise.
3.16 Consumer, Installer, and End-User
Information
Consumer demand for specific products (e.g., insect-re-
sistant wool products) is the ultimate driving force be-
hind textile manufacturing. Unfortunately, many, if not
most, consumers are unaware of the pollution the textile
plant generates in an effort to satisfy consumer demand.
In addition, consumers are often confused by "green"
claims (see Section 3.13, "Disinformation About Envi-
ronmental Issues") that are made in the absence of
standard regulations and definitions (see Section 3.15,
"Standard Tests, Methods, and Definitions"). As a result,
consumers may express preferences for products with
certain attributes or qualities with little or no knowledge
of the pollution generated to produce those products.
Consumers need to be educated about textile manufac-
turing processes and the pollution resulting from these
processes in order to make better-informed choices in
the marketplace.
Better-informed consumers can result in:
• Reduced demand for high-pollution products
• Improved life expectancy (durability) of textile products
• Less pollution from use, cleaning, and maintenance
• Better installation and use
• Enhanced postconsumer recycling of textile products
Consumers, however, should not bear all responsibility
for a market that demands high-pollution products. Al-
though many textile manufacturers have initiated effec-
tive pollution prevention within individual process lines,
few, if any, have applied a global approach that broadly
integrates pollution prevention from fabric designer to
consumer.
Integration and coordination are the keys to maintain-
ing pollution prevention all the way along the process-
ing chain from raw material to yarn to fabric to textile
product. Many of the difficulties of achieving global
pollution prevention efforts have already been dis-
cussed. The basic dilemma is that pollution prevention
efforts undertaken at one stage of processing may
only benefit downstream operations. Unless they are
all part of an integrated operation, no mechanism
exists for upstream operations to recoup the costs or
reap the benefits of any pollution prevention initiatives
they may undertake.
Further difficulties arise when textile materials are com-
bined with other raw materials to produce final consumer
products (e.g., furniture). Often, textile manufacturers do
not know which materials will be combined or in what
manner they will be combined after they leave the mill.
For example, in furniture upholstering, upholstery fabric
can be combined with batting, fiberfill, open or closed
cell foams, and stiffening innerliners. Problems arise
when consumer product manufacturers lack good infor-
mation about incompatible material combinations, espe-
cially those that could produce pollution such as indoor
air emissions, sorption, and reemissions. This makes
product design difficult for all involved.
Accurate, clear consumer information on product use
with respect to aftermarket treatments, cleaning sol-
105
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vents, use conditions, installation and maintenance, and
recycling is also needed. High and low polluting prod-
ucts (in terms of manufacturing) need to be accurately
identified to the customer. In addition, better information
on material combinations is needed. In short, a clear
need exists to provide better information on product use,
installation, and material combinations to all involved,
including textile producers, consumer products manu-
facturers, and customers. Marketing is a crucial link in
this chain. Some industries (e.g., Pharmaceuticals) do
an excellent job of informing consumers, and the textile
industry can learn from these industries. In addition, the
textile industry needs to emulate other successful tech-
niques such as better technical product bulletins and
product specifications. Providing this information would
also help avoid certain common quality problems such
as color bleeding of knit shirts with contrasting collars.
3.17 Segregation and Direct Reuse
One cornerstone of good waste management is that
individual waste streams must be separately captured,
segregated, and stored to maximize the potential for
recovery, recycle, and reuse. This is true for waste
streams from several textile processing operations in-
cluding preparation, dyeing, printing, and finishing (see
Sections 4.9, "Preparation," 4.10, "Dyeing," 4.11, "Print-
ing," and 4.12, "Finishing," for more detailed descriptions).
For example, in printing operations, Malone suggests
that, when producing many special customer colors,
excess material and overproduced material should be
held in inventory until a suitable use is found (18). The
stored excess can be used as a component in a new
color mixture (see Section 4.11, "Printing").
New machinery is available with built-in features that
facilitate recovering and reusing waste streams. One
example that can be widely applied in textile processing is
the Scholl BLEACHSTAR. This machine has built-in facili-
ties for waste stream segregation and capture (see Sec-
tion 3.19, "Pollution Prevention Through New Equipment").
In addition, some facilities use multiple waste handling
systems to segregate wastewater for more efficient
reuse or treatment into:
• Noncontact cooling water.
• Stormwater from parking lot and roof drains.
• Cleanup water from machines, facility, and filter back-
wash.
• Process wastewater from preparation, dyeing, and
finishing.
In the future, facilities and equipment will require even
further segregation of wastewater. For example, highly
colored or high salt content wastes can be better han-
dled if separated from other waste streams. Reuse and
treatment of these pollutants are expensive. Keeping
these wastes separate from other wastes is essential to
keeping the treated volume low.
3.18 Improved Process Control
In the past, control systems in textile operations involved
the automation of existing manual methods. In many
cases, these methods have been enhanced with attrac-
tive graphic displays and other aesthetic improvements,
but the underlying control protocol remains the same as
with the manual methods. A new generation of innova-
tive control systems is being developed that actually
uses more capabilities of microprocessors. Some are
hard automated systems, and others employ sophisti-
cated fuzzy logic or neural network control strategies.
These are described in more detail in Section 3.19,
"Pollution Prevention Through New Equipment," but are
briefly mentioned here as well. Some examples are:
• Automated mix kitchens
• Chemical dosing systems
• Direct dyebath monitoring and control systems
• Real-time sensors and advanced control strategies
• Real-time multichannel adaptive control systems
• Scheduling and management systems
3.18.1 Automated Mix Kitchens
Automated mix kitchens are used for making print
pastes and finish mixes, and for dye dispensing (both
powder and liquid dyes). Laboratory systems are also
available. These improve the speed and accuracy of dye
and chemical dispensing, and eliminate a substantial
amount of waste. For further information, see Sections
3.19, "Pollution Prevention Through New Equipment,"
and 4.18, "Support Work Areas."
3.18.2 Chemical Dosing Systems
Chemical dosing systems are similar to automated mix
kitchens; however, they actually meter dyes or chemi-
cals into the process. Dosing systems can produce
many more dosing profiles and can be computer con-
trolled and integrated with other dyehouse functions
such as scheduling. For further information, see Sec-
tions 3.19, "Pollution Prevention Through New Equip-
ment," and 4.10, "Dyeing."
3.18.3 Control, Automation, Scheduling, and
Management Systems
Modern control systems typically control parameters
such as:
• Air exhaust and moisture control from dryers
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• Chemical feed or addition
• Cooling and heating
• Draining and filling
• Incident (tangle) alarm
• Pressure control, speed, flow, and temperature
These control systems follow a predetermined process
routine and can be programmed with extreme accuracy.
Pollution decreases with these systems because the
improved control increases the likelihood of right-first-
time processing. This saves time, energy, and chemi-
cals, and facilitates chemical handling within the
operation.
3.18.4 Real-Time Sensors and Advanced
Control Strategies
One innovation that has occurred at the front end of many
control systems is the adoption of rapid, accurate, real-
time sensors. These enable the operator to monitor and
evaluate important process parameters. In many systems,
predictive models are embodied in the controls, which can
make quick changes, adjusting operating variables to
achieve the desired result. Some applications of these
systems, which are discussed in Section 3.19, "Pollution
Prevention Through New Equipment," are:
• Dryer efficiency and air pollution improvement
• Direct dyebath monitoring and real-time control
In these applications, traditional control strategies are
replaced with innovative strategies that adaptively ad-
just in real time to compensate for uncontrollable pa-
rameters. This allows a better chance of right-first-time
results despite raw material and other variations (55).
3.19 Pollution Prevention Through New
Equipment
Equipment design, maintenance, and operation are es-
sential elements of an effective pollution prevention pro-
gram. During the last few years, certain new equipment
concepts, as well as modifications to existing equipment,
have appeared that directly contribute to the reduction of
pollution from textile processing operations. Some of this
equipment is mature and commercially proven, and is
being readily adopted by textile mills as thesy replace older
equipment. Other ideas are still unproven but show prom-
ise and deserve attention as attempts to bring them to a
state of. commercial usefulness progress.
3.19.1 Proven Commercial Technologies
The most notable proven, mature, commercial technolo-
gies are:
• Automated mix kitchens.
Built-in bath reuse facilities on dye machines.
Chemical recovery systems for caustic and size.
Chemical dosing systems.
Continuous knit dyeing ranges.
Control, automation, and scheduling management
systems.
Countercurrent washing.
Heat recovery systems.
Humidity sensors and advanced controls for drying.
Incinerator dryers.
Low-bath-ratio dyeing systems.
Mechanical finishing (e.g., compacting).
Pad-batch dyeing machines for fiber-reactive dyes.
Quick-change pads on continuous ranges.
Transfer printing machines.
Laser engraving of printing screens.
Low add-on finishing.
Waste reclamation systems for spinning.
Water recovery systems.
3.19.1.1 Automated Mix Kitchens
Several manufacturers now offer automated mix kitch-
ens for making print pastes and finish mixes. They also
offer versions for dye dispensing of powder or liquid
dyes in batch or continuous dye houses. In addition,
similar systems are also available for the laboratory to
improve speed and accuracy in color matching. The
industry is beginning to adopt these systems and is
using them in more sophisticated operations. In many
cases, these systems connect directly to IBCs, and thus
eliminate the potential for dye spillage, requirements for
implement cleanup, and other polluting manual work
practices. These systems also increase the accuracy of
dispensing, and odd-sized mixes can be made to ex-
actly accommodate varying lot sizes in continuous op-
erations, thus reducing discards. For further information,
see Section 4.18, "Support Work Areas."
3.19.1.2 Built-in Bath Reuse on Dye Machines
Several dyeing machine manufacturers offer machines
featuring holding tanks that can store processing baths
for reuse. In most cases, each machine has two or three
of these holding tanks. These tanks accommodate
reuse of preparation, dyeing, and wash baths, thus re-
ducing water consumption. These machines are easily
recognizable by the large holding tanks mounted beside
107
-------
the main kier. A sample configuration and a sample
procedure for bleaching are shown in Figure 3-9.
A related configuration is the dual-kier system. Manufac-
turers have offered these systems for some time in
package dyeing, and now offer them for piece dyeing
machines as well. These systems allow processing bath
to be pumped back and forth between two different
dyeing kiers for reuse purposes.
For further information on dyebath reuse, see Section
4.10, "Dyeing."
3.19.1.3 Chemical Recovery (Caustic and Size)
Caustic soda (sodium hydroxide) and certain warp size
materials can be recovered for reuse with commercially
available systems based on ultrafiltration, hyperfiltration,
reverse osmosis, or evaporative recovery methods. Tex-
tite.mills have adopted these systems but not as widely
as would seem to be merited. Barriers to further use of
recovery include logistical difficulties, and the need to
segregate waste streams. In cases where mills do adopt
these systems, the result can be outstanding cost and
pollution savings. A schematic of the equipment for
these recovery systems is shown in Figure 3-10. For
further information on size and size recovery, see Sec-
tion 4.7, "Slashing and Sizing."
3.19.1.4 Chemical Dosing Systems
Chemical dosing systems are somewhat similar to the
automated mix kitchens discussed above in that they
provide many of the same pollution prevention advan-
tages. The function of these systems, however, is more
than simply to weigh out the correct amount of material
to make a mix. These chemical dosing systems meter
the chemical into the dye process according to a specific
dosing strategy. For years, dyers have manually added
salt and buffers to dyeings according to specific chemi-
cal dosing versus time schemes. Dosing systems auto-
mate this function, make many more dosing schemes
available, and can be computer controlled. This im-
proves reliability of the dosing process, thereby increas-
ing the replicability of results and the probability of
Example Procedure:
1. Bleach: Fill from Tank A; bleach; drain to pit.
2. Hot Rinse: Fill 650 gal from Tank B; drain to Tank A.
3. Hot Rinse: Fill 650 gal from Tank B; drain to Tank A; Tank A is full.
4. Warm Rinse: Fill 650 gal from Tank C; drain to Tank B.
5. Warm Rinse: Fill 650 gal from Tank C; drain to Tank B; Tank B is full.
6. Neutralize: Fill 650 gal from fresh water; drain to Tank C.
7. Final Rinse: Fill 650 gal from fresh water; drain to Tank C; Tank C is full.
Tanks A, B, and C are full and ready for next process.
Figure 3-9. Dyeing machine configured for dyebath reuse (56).
108
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Warp
Virgin PVA
Reusable
Hot
Water
(Permeate)
Lint and Waste
Figure 3-10. Schematic of PVA size recovery.
right-first-time dyeing. For further information about dos-
ing systems, see Section 4.10, "Dyeing."
3.19.1.5 Continuous Knit Dyeing Flanges
Continuous dyeing offers certain pollution advantages
compared with batch dyeing. One limitation of conven-
tional continuous dyeing ranges, however, is their inher-
ently high tension and therefore their inability to run
knits. Several equipment manufacturers have recently
introduced continuous knit dyeing ranges. These feature
tensionless knit handling, dye application systems that
avoid tubular edge marks, suitable guidance systems for
knits, and other such features to overcome the limita-
tions of continuous dye ranges. The ability to run knits
by continuous dyeing methods presents many new pos-
sibilities, including the use of vat dyes for green shades
(thus eliminating metal-bearing reactive dyes from for-
mulas), elimination of salt from effluents, and increased
flexibility for dye class selection. A diagram of a typical
continuous knit configuration is shown in Figure 3-11.
3.19.1.6 Control, Automation, and Scheduling
Management Systems
One major change in the textile industry during the past
20 years has been improved process controls. Modern
microprocessor technology enables each machine to be
controlled according to a predetermined process specifi-
cation. These systems perform tasks such as controlling:
• Air exhaust rate (ovens)
Reusable
PVA
(Concentrate)
• Chemical feed or addition (dye machines, bleach ranges)
• Cooling
• Draining
• Filling (dye machines)
• Heating
• Incident (tangle) alarm
• Moisture control (dryers)
• Pressure control
• Speed or flow control
• Temperature
Once a predetermined optimized process is pro-
grammed into the controller, these and other tasks can
be handled automatically, and the system reports to the
supervisory computer all exceptions and other pertinent
information about the process. One indication of the
commercial impact of these new controllers is that the
ITMA 1987 textile equipment show in Paris, France,
comprised more companies showing controllers than
companies showing dyeing machines. These controllers
reduce pollution by improving:
• Probability of right-first-time processing
• Process conformance to standards
• Use of time, energy, and chemicals
109
-------
Padding: Dye + Alkali
Salt Bath, Steaming
Washing Off
Steps
Time
Temp.
Pick-up
Padding
6 sec
Penetrating
60 sec
20-30°C
90-120%
Levelling
15660
90
ca. 400%
Fixing
75 sec
103
90-120%
Rinsing
10min
20
10mln
70
Soaping
10min
95
10min
95
Rinsing
10min
70
10min
40
ca. 400%, after squeeze 140%
Figure 3-11. Continuous dyeing of tubular cotton knits (57).
• Equipment operations audit
• Chemical handling practices
One such system is shown in Figure 3-12. It interfaces
the management information system with dosing, blend
watertemperatures, dyeing machine control, report gen-
eration, automatic drug room, and other functions.
3.19.1.7 Countercurrent Washing
The practice of countercurrent washing is widely prac-
ticed in textile operations. This involves introducing raw
water into the last of a series of washing steps, then
circulating the wastewater from the last step to the next
preceding step and so on up the line. In this way, the
cleanest fabric is washed with the cleanest water, and
the most contaminated fabric is washed with the least-
pure water. This results in a huge water savings in
multistep washing operations. For example:
Number of
Washing Steps
2
3
4
5
Water Savings
(percent)
50
67
75
80
Some washing equipment (i.e., horizontal washers) has
the same inherent counterflow characteristics built into
the design. In all washing steps, using the correct flow
is essential. Excessive flow wastes water, and insuffi-
cient flow results in bad work.
Further information about countercurrent washing may
be found in Section 2.2.7, "Water Conservation."
3.19.1.8 Heat Recovery
Many types of successful heat recovery systems have
been developed, and the textile industry has started to
adopt these systems widely in wet processing opera-
tions. The collection systems for water often feature
underflow dams and other devices to stratify water be-
fore sending it to the heat exchanger. The recovered
heat is useful in washing and fill water for the dye house.
3.19.1.9 Humidity Sensors in Drying
Dryer efficiency and air pollution are significant con-
cerns with tenter frames and other drying devices (e.g.,
yarn dryers). Many important factors must be controlled,
including the temperature of the dryer, the time of heat-
ing, the makeup air supply, and the humidity in the dryer.
If the temperature is too high, undesirable dye and finish
migration occur. If the temperature is too low, drying
requires excessive time. Equally important is the humidity
in the dryer. When the humidity is too high because of
insufficient introduction of makeup air, moisture evapo-
rates very slowly. If the makeup air is excessive, however,
the humidity is very low and the drying is rapid, but exces-
sive energy is required to heat the makeup air. Also,
increasing the makeup air causes the oven exhaust to emit
110
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DYEMAX Controller
May be mounted in
dye office as shown or
in machine operators
panel
MUX
IBM AT
Optional Host IBM PC
- Monitors machine status
- Downloads programs
to controller
- Produces batch reports
- Produces efficiency reports
Automated Drug Room
Signals operators to prepare tanks.
At proper time, transfers dye/chemicals
to side tank at machine and rinses
tanks. This means dye/chemicals are
added at exactly the correct time and
temperature. This results in better
quality dyeing, exact repeats, and fewer adds.
Programmable
Logic Controller
Located in machine operator
panel. Handles all digital inputs
and outputs. Communicates
with controller via two-pair wires.
"
Cold
Blend
?
«^l C&
Jet, Package, Beam, •
and Beck Dyeing Machine
—t£l Steam
Cool Out
Cond.
Cool
Blend Water Temperature Control.
Enables fill/rinse with water at
preprogrammed temperature
Pump
Volume Metering
Einables fill/rinse with
exact water volumes.
Dye/liquor ratios may
te repeated exactly.
Precise dosing of dye/chemicals
QTY-TIME-CURVE
Figure 3-12. Automated process control system (58).
more air pollutants. Humidity monitors in the dryer pro-
vide real-time data to a system that controls exhaust
dampers and makeup air to optimize dryer performance
in terms of energy use, dye migration, and air pollution.
3.19.1.10 Incinerator Dryers
Another improvement in dryer efficiency is the use of
incinerators or thermal oxidizers on the dryer exhaust to.
destroy contaminants in the discharge air stream. Heat
can then be recovered from the exhaust gas and recy-
cled into the dryer as preheated air.
3.19,1.11 Low-Bath-Ratio Dyeing Systems
One important parameter in batch dyeing is the bath
ratio;' or the ratio of the mass of the dyebath to the mass
of the goods in the dyeing machine. The bath ratio varies
greatly from one type of dyeing machine to another. In
recent times, jet and package dyeing machines have
been introduced with ever-decreasing bath ratios. In the
1960s, bath ratios of 12:1 were the norm. Some of the
newest dyeing machines, called utra low liquor ratio
(ULLR) machines, have bath ratios of 3:1 for synthetics
and 5:1 for cotton. The machine shown in Figure 3-13
runs at 5:1 and below.
111
-------
These low bath ratios have been accomplished through
new engineering design concepts for the machines. The
pollution prevention advantages of the lower bath ratio
are less:
• Salt required for exhaust dyeing on cotton
• Dyebath chemical required
* Unfixed dye at lower bath ratio
• Energy required to heat up dyebaths
• Time required to fill and drain machine
• Water used
One vendor's cost comparison of low-bath-ratio jets with
other dyeing machines is given in Table 3-16. The higher
productivity and lower water, steam, and chemical costs
produce savings estimated at $0.0835 per pound dun-
ning polyester/cotton and 100 percent cotton (56).
Based on 100,000 pounds per week production running
52 weeks per year, the total annual savings amount to
$.0835 X 100,000 X 50 = $417,500.
In addition, some machines (air jets) use air, not water,
as the transporting mechanism. These machines were in-
troduced in 1975, but the early models were not successful.
The latest is the then AIRFLOW, which reportedly can
run at bath ratios of 2:1 or less.
Further information on low-bath-ratio dyeing may be
found in Sections 2.2.2, "Discharge of Electrolytes," and
4.10, "Dyeing."
Table 3-16. Estimated Savings With ULLR Dyeing Equipment
(56)
Conventional
Parameter Equipment
Bath ratio
Productivity
Cost Factors
Water
Steam
Electricity
Direct labor
Chemicals
Supplies
Overhead
Total
10:2
282.77
0.0189
0.0161
0.0052
0.0309
0.138
0.0089
0.0424
0.2604
ULLR
Equipment
5:1
316.39
0.0119
0.008
0.0052
0.0277
0.0774
0.0088
0.0379
0.1769
Change
—
33.62
-0.007
-0.0081
0
-0.0032
-0.0606
-0.0001 '
-0.0045
-0.0835
Percent
Change
—
11.9
-37.0
-50.3
0.0
-10.4
-43.9
-1.1
-10.6
-32.1
3.19.1.12 Mechanical Finishing (Compacting)
Several methods exist for providing desired end-use
performance in terms of shrinkage control, softness,
width, yield, and other factors without using chemical
finishes. Atypical method is compacting, a process that
preshrinks fabrics to a stable configuration, thereby
eliminating the need for cross-linking resins, which con-
tain formaldehyde. Compactors have been widely
adopted in the textile industry and are very reliable for
both knits and wovens. Several types of machines are
Loading and Unloading
Winch
Dye Liquor Acceleration Device
Additions Vessel
rr*h
,vM> .\
LSsl. _/1
'*"• ^'ft.SSSSS*/* I rsJf~SSS?S?M
Y
^^ rMr^/^t c«^
Additions
Pump
Overflow*""'I"1'• /''.•'.'•'•y '•
Valve ^
Direct Feed " Drain
Figure 3-13. ULLR piece dyeing (56).
112
-------
available, employing rubber belts or sets of rolls with
differential speeds. A diagram and explanation of the
rubber-belt type is found in Figure 3-14. For further
information on mechanical finishing, see Section 4.12,
"Finishing."
3.19.1.13 Pad-Batch Dyeing of Fiber Reactives
The most popular method of batch dyeing of cotton,
especially cotton knits, js fiber-reactive dyes. These
have the disadvantage of producing excessive color and
salt in wastewater when applied by batch methods. The
pad-batch dyeing system eliminates these problems,
and allows knits to be dyed semicontinuously with fiber
reactives, but without salt, and increases fixation typi-
cally well above 90 percent. This method uses special
padders and tubular knit guiding and handling equip-
ment to ensure even dyeing without distortion or stretch-
ing of the knit fabric. Equipment configurations resemble
the continuous knit ranges in Figure 3-11. For further
information on pad-batch dyeing, see Section 4.10,
"Dyeing."
3.19.1.14 Quick-Change Padders on Continuous
Ranges
One major limitation of continuous dye ranges is the cost
of stopoff, startup, and color changes. Generally, a cer-
tain amount of fabric must be sacrificed before achieving
a steady state of running. Also, some dye solution must
be discarded from lines, pumps, and pad troughs. This
causes time loss, pollution, and expense. To minimize
such losses, several manufacturers now offer quick
changeover pads, which have very small volumes and
can drop down and swing away from the fabric path to
facilitate rapid dumping and cleaning. Schematics show-
ing how these systems operate are shown in Figure
3-15. Further information may be found in Section 4.10,
"Dyeing."
3.19.1.15 Transfer Printing
Similar start-up and stop-off losses associated with pat-
tern or color changes occur in the printing process. One
way to avoid these losses for printing of disperse dyes
on polyester is through transfer printing. This technique
prints the disperse dye onto a paper substrate, then
transfers the dye under high temperature and pressure
onto the polyester fabric by sublimation. Overall, this
method accounts for approximately 6 percent of all print-
ing done today worldwide (61).
Transfer printing offers many advantages, including:
• Color changeovers are essentially instantaneous.
• Short runs are not a problem.
« Paper printing is more efficient than fabric printing.
• Cloth and paper are both preinspected, avoiding off-
quality printing.
• Textile mills can start printing with minimal capital
outlay.
• Cost per unit of fabric printed is lower.
Transfer printing equipment is simple, consisting of only
a heated cylinder and a blanket or other means of
maintaining contact between the fabric and the paper.
The limitation of the system is that it only works for
disperse dyes. A diagram of a transfer printing machine
is shown in Figure 3-16. For further information on trans-
fer printing, see Section 4.11, "Printing."
1 = Driven Spreading Rollers
2 = Steaming Drum
3 = Rubber Belt Unit
4 = Drying Cylinder
5 = Low-Tension Unwinder/Winder
Figure 3-14. Mechanical shrinking of goods using rubber-belt method (59).
113
-------
oo
Production
Dump
Rinse
Fill
Figure 3-15. Quick-change S-roll pad to reduce startup, stopoff, and changeover losses (60).
3.19.1.16 Laser Engraving of Printing Screens
Conventional methods of print screen making involve
photographic processes, manual film making, registra-
tion verification, and, finally, working with lacquer-coated
screen material to produce a rotary screen. New laser
engraving techniques allow for direct digital scanning (or
on-screen design) of patterns, thus avoiding toxic pho-
tographic silver residues. The quality of the screens is
also better. A typical setup includes a digital scanner,
CAD workstation, and the engraver, which uses a he-
lium-carbon dioxide laser. Several systems have been
installed in the United States in recent years.
3.19.1.17 Low Add-On Finishing
Several types of low add-on finishing machines are
available. All types apply a very low amount of finish
solution to the fabric, thus reducing energy and chemical
use. Some of the more popular methods are (40):
• Ultra high extraction with vacuum
• Sprays
• Foams
• Kiss rolls
Vacuum extraction is used in many ways to reduce
pollution in textile wet processing operations. The most
simple way is to reduce the water content of fabric
before it goes into a drying process. Reducing the mois-
ture mechanically by vacuum reduces the heat energy
required to dry the fabric. This means faster dryer
speeds and lower costs. Also, finishing at lower WPU
levels offers many advantages, including reduced
chemical use. Other applications related to pollution
prevention include the ability to avoid dragout and car-
ryover of processing solutions from one processing step
to the next. This can, for example, increase the effi-
ciency of washing. High-extraction, low-carryover proc-
ess step separations generally prevent pollution. Tests
of the EVAC system of vacuum finishing showed that for
a given crease recovery angle performance, fabrics
show less strength loss using the vacuum-extracted
finishing method. The vacuum-extracted finishing sam-
ples had lower formaldehyde release for the same level
of performance, and fewer chemicals were used than in
conventional finishing (62).
The EVAC vendor reported trials showing impressive
results. For example, Table 3-17 shows the results ob-
tained in one trial. The test showed that equal or better
shrinkage control could be obtained using low add-on,
wet-on-wet finishing, with lower chemical and energy use.
Foam finishing uses air to dilute the water in a chemical
solution, thus lowering the WPU of the fabric and the
114
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1. Textile
2. Protective Paper
3. Transfer Paper
Figure 3-16. Transfer printing of disperse dyes on polyester (61).
energy required for drying. Foams can be somewhat
hard to control, but they are useful in certain applica-
tions. Carpet dyeing and certain backcoating operations
are done with foam. A typical foam setup is shown in
Figure 3-17 for foam finishing of tubular knit fabrics.
High extraction for moisture removal before drying is
shown in Figure 3-18. It uses a high-velocity steam jet
plus vacuum to blow out the excess moisture.
For more information on low add-on finishing, see Sec-
tion 4.12, "Finishing."
Table 3-17. Results of Tests on Knit Finishing System Using
Vacuum Technology9
Shrinkage percentage (length x width)
Fabric
Untreated
Low Add-On
Conventional
lnterlock(k)b
Jersey(k)
Sheeting(w)d
Twill(w)
15x4
12x2
8x3
11 xO
6x+2°
7x+1
2x0
3x0
6x3
8x3
2x1
3x1
aTyndall, M. 1989. Memorandum from Mike Tyndall, Cotton, Inc.,
Raleigh, NC, summarizing results of tests of the EVAC Ultraknit trial
(May 8).
b k = knit.
° + = growth.
w = woven.
FFT Foam Applicati
rnr
Top View r
1 i
on
[
Ra
If
nge
I/—-
Cloth
"~^
Control Rolls
i
^ i i
.-— •
1
i
1
h
J-
5
(
FT r
I
) inches
127cm)
I
L L
•I
/ la
nr
1 1
LJ L
75 inches
(191 cm)
To
Dryer
^~~t
I
Cloth Entry
Side Drive Taper Roll
Foam Applicator
Tabletop Chemical Foamer and
Feed System
O
E
S
5S
J_
Side View
83 inches
(211cm)
16 feet 4 inches
(498 cm)
Draw
Roll
n
Dryer
Chemical Foamer
and Feed System
-73 inches (1.85m)
Figure 3-17. Foam finishing for low add-on (63).
115
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8 feet 10 inches
• (269 cm}
5 feet 10 Inches
{178cm)
5 feet 8 Inches
(173 cm)
10 feet 0 inches
(305 cm)
tl sl 6 feet 4 inches
(193cm)
30 feet 10 1/2 inches.
91/2 inches
(24cm)
5 feet 81/2 inches
(174 cm)
7 foot 3 inches
(221cm)
Top View (941cm)
Exhaust
K^el Extractor Detwister
(~\ /" Edge Drive
' • ' &»=•_ • -•=-. /
Floor
Entry
Side View
7 feet 8 inches
(234 cm)
Hydraulic
Turntable
Figure 3-18. High-extraction removal before dyeing (64).
3.19.1.18 Waste Reclamation in Spinning
Part of every cotton spinning operation involves the
removal of undesirable impurities, trash, and tangled
fiber masses from the raw cotton stock. In the past, this
nonreworkable waste was discarded. Now, systems are
available to collect it at its sources and reprocess it to
recover lint. The recovered lint is recycled into other
cotton spinning operations, while the approximately 1.5-
percent residual trash can be sold for reuse in padded
mailing envelopes or compressed into extremely high-
density fuel pellets for boilers. For further information,
see Sections 4.2, "Fiber," and 4.8, "Fabric Formation."
3.19.1.19 Water Recovery
Many systems are available that can recover water from
waste streams. The size and chemical recovery systems
described previously in this section recovered water as a
side benefit. Rlter-based decolorization systems also can
recover water in a reusable form. Other systems for reno-
vation of dyeing wastewater use ozone or chlorine.
3.19.2 Emerging Technologies
Many new technologies have been proven at the pilot
scale but have yet to be fully adopted by industry. Some
will no doubt be more successful than others. These
technologies show promise, however, and their com-
mercial development should be monitored.
The most notable emerging technologies include:
• Direct dyebath monitoring and control systems
• Real-time adaptive control systems
• Electrotechnologies
• Ink-jet printing
• Supercritical fluid dyeing
• Ultrasound dyeing
3.19.2.1 Direct Dyebath Monitoring and Real
Time Control
Traditional textile process control strategies are based
on defining an optimized process, then controlling the
machinery and services to conform as closely as possi-
ble with that process specification in terms of parame-
ters such as time, temperature, and machine speed. In
textile dyeing, for example, the fishbone diagram in
Figure 3-19 shows that the dyer cannot control many of
the variables. The traditional approach has been to ac-
cept the resulting shade variations and to compensate
for product variances by segregating each dye lot, rather
than mixing it with others (65).
New control strategies have been developed that adap-
tively adjust the process in real time to compensate for
uncontrollable parameters, thus arriving at the desired
result despite anomalies such as those that occur in raw
materials and utilities. This control system is based on
real-time adaptive dynamic control of the process, using
real-time data, and accurate prediction of final dyebath
116
-------
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' Q 3.
. S |s as S
"UHlt
I
en
I
TJ
1
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at
m
£
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ro
en
n:
U
I
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117
-------
exhaustion based on the dyebath state at any given
time. The control system then determines an optimized
predicted process necessary to reach the standard target.
One particularly useful parametric control model for that
purpose is the standard Langmuir kinetic model based
on the sorption and desorption rate constants (ka and kj
respectively), a parameter related to dye sites or dyeing
capacity of the fiber (S), and solution and fiber concen-
trations of dye at any time (cs and cf respectively):
dc'/dt = -dcs/dt = (Eq. 3-6)
[k. cs (S-cf)] - [kd cf]
Process control strategies based on the above paramet-
ric model have been highly successful for real-time con-
trol of processes involving individual dyes. Given the
necessary parameters, which are estimated in real time
from the progress of the dyeing itself, the control algo-
rithm determines conditions and time at which a desired
percentage exhaustion will be reached. Data from ordi-
nary production dyeings can be used to construct pre-
dictive models of dye process behavior, including, for
example, temperature dependance of the above pa-
rameters for individual dyes. In this way, real-time adap-
tive control models can be developed without extensive
test dyeings on production machinery.
3.19.2.2 Ink-Jet Printing
Commercial units are being offered for ink-jet printing,
In which droplets of dye solution are directed toward
specific spots, thus forming a pattern (67). The method
Is not yet commercial but holds promise as an emerging
technology. The need for photographic screen-making
and most color mix kitchen activities are eliminated.
Significantly fewer chemicals are required, and pat-
tern/color changes are simple. This method produces
virtually no cleanup waste. Ink-jet printing is a well
known method in document printing, and it can easily be
applied to textile fabrics too.
3.20 References
1. Holtod, Q.J., and R.F. McCartney. 1988. Waste reduction in the
chemical industry: DuPont's approach. E.I. du Pont de Nemours
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2, Morris, H. 1991. Playing by the rules. Indus. Fabric Products
(September), p. 106.
3. Smith, B. 1992. Source reduction: Alternative to costly waste
treatment. Amer. Textiles Int. (ATI) (March).
4. Glover, B., and L. Hill. 1993. Waste minimization in the dyehouse.
Textile Chem. and Colorist (June), p. 15.
5. Smith, B. 1987. Troubleshooting in textile wet processing—An
overview. Amer. Dyestuff Reporter (February), p. 28.
6. Brosky, D.L. 1992. Pollution prevention: Part of your waste man-
agement program. Water Sci. Tech. 26{1-2):289.
7. Berglund, R.L., and G.E. Snyder. 1990. Waste minimization: The
sooner the better. Chemtech (June), p. 740.
8. Smith, B. 1989. Pollutant source reduction: Part 4—Audit proce-
dures. Amer. Dyestuff Reporter (June), p. 31.
9. Heap, S.A., and J. Stevens. 1993. Engineering of knitted fabrics
using starfish. COTTECH Conference, Raleigh, NC (November
11-12).
10. Richardson, G.A. 1990. Are textiles finishing the environment: A
case study. Textile Institute Finishing Group Conference, Man-
chester, England (May 8).
11. Easton, J.R., and J.R. Provost. 1993. Pollution control and the
textile printer. Int. Dyer (September), p. 21.
12. Tyndall, R.M. 1994. Relaxed knit fabric finishing and compacting
(tubular and open-width). Amer. Dyestuff Reporter (April), p. 28.
13. Richardson, R.W. 1987. Saving water in the dyehouse by recy-
cling and plant design. Int. Dyer, Textile Printer, Bleacher, and
Finisher. 159(6):258.
14. Bide, M. 1994. Letter to editor. Textile Chem. and Colorist
(August).
15. Richardson, S. 1991. Multimedia environmental concerns in warp
sizing: Low tech approaches to waste reduction. North Carolina
Pollution Prevention Program, Raleigh, NC (February).
16. Hunt, G.E. 1989. Developing and implementing a waste reduc-
tion program. North Carolina Department of Environment, Health
and Natural Resources, Pollution Prevention Program, Raleigh,
NC (May).
17. Provost, J.R. 1992. Effluent improvement by source reduction of
chemicals used in textile printing. Textile Horizons (May/June).
p. 260.
18. Malone, N.H. 1990. Eastman Chemical Company's leadership
role in waste management. Int. Fiber J. (June), p. 30.
19. Shaw, T. 1989. Environmental issues in wool processing. Inter-
national Wool Secretariat (IWS) Development Center Mono-
graph. IWS, West Yorkshire, England.
20. Cooper, P. 1989. Are textiles finishing the environment? Interna-
tional Wool Secretariat (IWS) Development Center Monograph.
IWS, West Yorkshire, England.
21. Nagar, A.M. 1985. Optimum utilization of lubricants in textile mills.
The Indian Textile J. (December), p. 83.
22. Smith, B. 1987. Troubleshooting in dyeing—Part II: Batch dyeing.
Amer. Dyestuff Reporter (April), p. 13.
23. Wood, K.N., and A.L. Bishop. 1992. Effluent guidelines compli-
ance through waste minimization. Water Sci. Tech. 26(1-2):
301-307.
24. Modak, P. 1991. Environmental aspects of the textile industry: A
technical guide. Draft report. Prepared for the United Nations
Environment Programme (March).
25. Houser, N., R.S. Wagner, and B. Steelman. 1994. Pollution pre-
vention and U.S. textiles. Amer. Textiles Int. (ATI) (March), p. 28.
26. Smith, B. 1986. Identification and reduction of pollution sources
in textile wet processing. North Carolina Department of Natural
Resources and Community Development, Pollution Prevention
Pays Program, Raleigh, NC.
27. Smith, B. 1989. A workbook for pollution prevention by source
reduction in textile wet processing. Office of Waste Reduction,
North Carolina Department of Environment, Health, and Natural
Resources, Raleigh, NC.
28. Cook, F.L. 1991. Environmentally friendly: More than a slogan for
dyes. Textile World (May), p. 84.
118
-------
29. Howard, P.H., G.W. Sage, A. Lamacchia, and A. Colb. 1982. The
development of an environmental fate database. J. Chem. Info.
and Computer Sci. 22(1).
30. Tomasino, C. 1994. Expert system for managing the environ-
mental impact of textile auxiliaries. In: Cotton, Inc., year-end re-
port, July-December, 1994. Raleigh, NC.
31. Virkler Corporation, 1994. Fact sheet on environmental consid-
erations coding system. Virkler Corporation, Charlotte, NC.
32. Wagner, S. 1993. Improvements in products and processing to
diminish environmental impact. COTTECH Conference, Raleigh,
NC, (November 11-12).
33. Kravetz, L, JP. Salanitro, P.B. Dorn, K.F. Guin, and K.A. Ger-
chario. 1986. Environmental aspects of nonionic surfactants
(draft report). Presented at the American Association of Textile
Chemists and Colorists International Conference Exhibition, At-
lanta, GA (October 31).
34. Smith, B. 1994. Future pollution prevention opportunities and
needs in the textile industry. In: Pojasek, B., ed. Pollution preven-
tion needs and opportunities. Center for Hazardous Materials
Research (May).
35. Smith, B. 1988. Troubleshooting in finishing. Amer. Dyestuff Re-
porter (January), p. 35.
36. U.S. EPA. 1979. Development document for effluent limitations
guidelines and standards for the textile mills: Point source cate-
gory (proposed). EPA/440/1-79/0226. Washington, DC (October).
37. Wernsman, D. 1994. Annual progress report to the North Caro-
lina Office of Waste Reduction. Raleigh, NC. In preparation.
38. Moser, L. 1989. Case studies for textile printing. Pollution Source
Reduction in Textile Wet Processing, Raleigh, NC (May 23-24).
39. Horstrnann, G. 1993. The green dyer—fiction or reality. Aus-
tralasian Textiles (January/February).
40. Smith, B. 1985. Determining optimum wet pickup in low add-on
finishing. Amer. Dyestuff Reporter (May), p. 13.
41. Fulmer, T.D. 1992. Cutting costs and pollution: Save energy and
fight pollution at the same time. Amer. Textiles Int. (March), p. 38.
42. Mohr, U. 1993. Ecology must be dealt with. Australasian Textiles
(January/February), p. 45.
43. Williams, D.B. 1993. Techniques for pollution prevention in textile
wet processing. In: Proceedings of the Conference for Executives
and Managers on Environmental Issues Affecting the Textile In-
dustry, Charlotte, NC (June 14-15). North Carolina Department
of Environment, Health and Natural Resources, Raleigh, NC.
44. Holme, I. 1992. Finishers respond to "green" challenge. Textile
Horizons (November), p. 19.
45. Holme, 1.1992. Collaboration is the key to success. Textile World
(November), p. 33.
46. ENSCO. 1994. Waste material data sheet. ENSCO, Inc., El
Dorado, AR.
47. Mohr, U. 1993. Ecology must be dealt with. Australasian Textiles
(January/February), p. 45.
48. Zeller, M.V. 1975. Instrumental techniques for analyzing air pol-
lutants generated in textile processing. Textile Horizons (January).
49. Wilkinson, C.L. 1992. Environmental constraints will favor aque-
ous and hot-melt powder systems. Int. Dyer (October), p. 17.
50. Petty, J.B. 1981. Low energy dyeing of type 6 nylon carpet yam.
Amer. Dyestuff Reporter (June), p. 34.
51. Houser, N., R.S. Wagner, and B. Steelman. 1994. Pollution pre-
vention and U.S. textiles. Amer. Textiles Int. (ATI) (March), p. 28.
52. Wagstaffe, J. 1993. Automatic dispensing of dyestuffs. Aus-
tralasian Textiles (January/February), p. 42.
53. Int. Dyer. 1992. Computerized dispensing. (November), p. 17.
54. Achwal, W.B. 1990. Environmental aspects of textile chemical
processing, parts 1 and 2. Colourage (September), p. 40.
55. Smith, B. 1994. Waste minimization in the textile industry. Pre-
sented at the American Association of Textile Colorists and
Chemists (AATCC) Symposium, The Textile Industry 1994:
Achieving an Environmental Commitment, Charlotte, NC (March
24-25).
56. Scholl America. (No date). Product bulletins. Scholl America,
1515 Mockingbird Ln., Suite 404, Charlotte, NC 28209.
57. Vald. Henriksen a/s. (No date). Company newsletter: VHISION.
Vald. Henriksen a/s, Sydmarken 44, DK-2860 Soeborg, Denmark.
58. Select Controls, Inc. (No date). Technical data sheet: DYMAX—
Complete dyehouse. Select Controls, Inc., 4101 -D Stuart Andrew
Blvd., Charlotte, NC 28217.
59. A. Monforts GmbH & Co. (no date). Product bulletin on Mon-
fortex. A. Monforts GmbH & Co., P.O.B. 386, D-4050
MSnchengladbach 1, Austria.
60. Kusters Corp. (No date). Technical data sheet. Kusters Corp.,
885 Simuel Rd., Spartanburg, SC 29304-3274.
61. Stork Brabast, B.V. 1990. Developments in the textile printing
industry. Int. Textile Bull. Dyeing/Printing/Finishing (April).
62. Celmins, A.I. 1990. Improved 100 percent cotton shirting fabric
using EVAC vacuum technique and BTCA (Glo-Tex) reactant.
Unpublished report. Spartanburg, S.C.
63. Fab-Con Machinery Development Corp. (No date). Technical
data sheet: Fab-Con FFT system for foam application to tubular
knits. Fab-Con Machinery Development Corp., 103 Harbor Rd.,
Port Washington, NY 11050.
64. Tubular Textile Machinery Co. (No date). Product bulletin on jet
extractor range. Tubular Textile Machinery Co., P.O. Box 2097,
Lexington, NC 27293-2097.
65. Smith, B., G. Berkstresser, and K. Beck. 1994. Recent progress
in real time adaptive control of batch dying processes. In: Pro-
ceedings of the American Association of Textile Chemists and
Colorists, National Technical Conference, Charlotte, NC (October).
66. Koksal, G., W.A. Smith, and B. Smith. A system analysis of textile
operations: A modern approach for meeting customer require-
ments. Textile Chem. and Colorist 24(10):30.
67. Smith, B., and E. Simonson. 1987. Ink jet printing for textiles.
Textile Chem. and Colorist (August), p. 23.
119
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Chapter 4
Pollution Prevention in Specific Textile Processes
4.1 Introduction
This chapter identifies pollution prevention opportunities
in specific textile processes or operations. The chapter
roughly follows the stages of textile manufacture. It be-
gins with several sections covering raw rjiaterial handling
and use, including issues related to raw fiber production
and processing, dye selection and use, as well as
chemical specialties and commodities. Subsequent sec-
tions cover yarn formation, slashing and sizing, fabric
formation, textile preparation, dyeing, printing, finishing,
and cutting and sewing operations. Additional sections
go beyond the textile mill to address issues related to
installation of textile materials, aftermarket treatment of
textiles, consumer care issues, globalization of pollution
prevention, and pollution prevention in support work
areas.
Each section discusses environmental issues for that
particular part of the operation and identifies relevant
pollution prevention opportunities. A particular effort is
made to relate environmental problems in each phase
of operations to other stages of production, both up-
stream and downstream, and to highlight the connection
between operating practices in one part of the operation
and pollution problems elsewhere. A major theme of this
chapter is the need for a broader, more global approach
to pollution prevention, as summarized in Section 4.17,
"Globalization of Pollution Prevention."
4.2 Fibers
The following table introduces pollutants and waste
streams discussed in this section, as well as pollution
prevention activities suggested for each.
Pollutant or Waste
Stream
Pollution Prevention
Actions Described
in This Section
Comments
4.2, Fibers (General)
Residues from agricul- Incoming raw
ture, synthesis, and/or material QC
other upstream opera-
tions
,
Air and water
pollution results
during scouring
(see Section
4.9.1 .3) and
heated operations
(see Section 4.12)
Pollutant or Waste
Stream
Pollution Prevention
Actions Described
in This Section
Comments
4.2.1,1, Cotton
Natural waxes and oils Not preventable
Metals
Avoid use of
metal-based
agricultural
chemicals;
otherwise,
generally not
preventable
Minimize use
of agricultural
chemicals in
favor of
nonchemical
methods
Use water-based
lubricants and
cleaners, not
petroleum oils
Not preventable
Conservative use
and maximized
use of nonchemical
pest control
methods
4.2.2, Synthetic or Regenerated Fibers
Agricultural chemical
residues
Lubricant residues
from harvesting
4.2.1.2, Wool
Oil and grease
Pesticides
Fiber finishes
Optimum control of
finish add-on and
proper selection of
finish components
Unreacted or improp-
erly reacted polymer
synthesis or regenera-
tion residues
Optimized reaction
process and method
in fiber regeneration
or polymerization
Removed in
scouring (see
Section 4.9.1.3)
Removed in
scouring (see
Section 4.9.1.3)
Generally present
in very low levels;
of little concern in
normal operations
Use of water-
based cleaners
and lubricants is a
widespread practice
Removed in
scouring
Practices vary
greatly among
growth areas
Generally trade
secrets
Add-on levels
vary
Volatile and
hazardous
components
sometimes
used
A source of water
and air toxics
Includes many
materials such as
monomers,
oligomers, metals,
degradation
products, solvents,
and coagulants
121
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Pollutant or Waste
Stream
Pollution Prevention
Actions Described
In This Section
Comments
Additives
Optimum control of
add-on and proper
selection of additives
Trade secrets,
often applied with
varying add-on
levels, also often
containing
hazardous
components
42.3, Fiber Pollution
Residues from fiber
manufacture
Packaging wastes
Prevention Strategies
Incoming fiber QC
and producer
participation in global
pollution prevention
approach
Use of recyclable
bale wrapping,
straps, and ties
Residues are
removed or
vaporized during
scouring or heat .
treatment
operations
Widely practiced;
vendor
participation is
required
A wide variety of contaminants may already be present
in fibers when they arrive at the textile mill. During
processing, when the fabric (or yarn) is heated or
scoured, potential contaminants can be released into
the water and air as pollutants. Because of the massive
amounts of fiber used in textile manufacturing, even
trace contaminants can produce large amounts of pol-
lutants. In addition to the air and water pollutants re-
leased, a considerable amount of packaging waste,
such as bale wrap materials, is generated (see Section
1.2.3 for a discussion of these solid wastes).
Many textile operations lack an incoming quality control
(QC) system for fibers. Some operations test cotton
fibers for physical properties such as micronaire, length,
strength, color, and nonlint content. Few if any mills test
for contaminants, however, and almost no mills test
synthetic fibers, despite the variability and pollutant po-
tential of synthetics.
Richardson (1) discusses the importance of checking
incoming fibers for impurities and residues from pre-
vious processing. Standard fiber-extraction tests for
water-, enzyme-, and solvent-extractable materials are
available for testing incoming fiber (2). These methods
can detect oils, fats, waxes, spin finishes, lubricants,
starches, and other contaminants. Standard test meth-
ods also can be easily adapted to detect specific con-
taminants by simply performing the appropriate tests on
the extracts obtained. Traditional effluent tests such as
those for detecting biological oxygen demand (BOD)
and chemical oxygen demand (COD) as Well as chemi-
cal-specific tests can be used, in addition to high-per-
formance liquid chromatography (HPLC) and gas
chromatography/mass spectrometry (GC/MS) for or-
ganics, and inductively coupled plasma (ICP) for metals.
Most commercial wastewater laboratories can perform
these tests at reasonable costs.
4.2.1 Natural Fibers
Natural fibers are acquired from animal, mineral, and
plant sources (see Table 4-1). Several types of contami-
nants are found in natural fibers, and all have the poten-
tial to create significant pollution problems. Table 4-2
identifies the contaminants found in natural fibers along
with a brief description of the resulting pollution prob-
lems. For example, waxes and oils from animal-derived
fiber can contribute to BOD, COD, as well as fats, oil,
and grease (FOG), and pesticide residues can contrib-
ute to aquatic toxicity. Metals can accumulate in sludges
or in the treatment system itself, causing potential long-
term problems.
As shown below, natural fibers exhibit great variability in
quality and extent of contamination and thus should
receive attention in any pollution prevention program. A
comprehensive incoming raw material QC program is
highly advisable to detect and control these contami-
nants before they become serious pollution problems.
4.2.1.1 Cotton
Cotton is by far the most commercially significant natural
fiber in the United States. Cotton's relative ease of pro-
duction and its applicability to a wide variety of textile
products contributes to its popularity. Cotton production,
however, may use chemicals such as pesticides and
herbicides, and these may remain as a residue on raw
cotton fibers that reach the textile mill. Modak (3) has
reported that raw cotton contains pesticides, fertilizers,
and defoliants. Tests of cotton performed from 1991 to
Table 4-1. Natural Fiber Sources
Animal Mineral
Plant
Wool
Silk.
Other hair-fibers
Alpaca
Camel
Cashmere
Horse
Llama
Mohair
Rabbit •
Vicuna
Asbestos
Glass
Metallic
Copper
Steel
Cotton
Flax
Hemp
Jute
Linen
Ramie
Table 4-2. Natural Fiber Contaminants and Associated
Pollution Problems
Contaminant
Resulting Pollution
Natural waxes and oils
Metals
Agricultural residues
BOD, COD, FOG
Aquatic toxicity, treatment system
inhibition, accumulation in sludge
Aquatic toxicity
Lubricant residues arising from BOD, COD, FOG
harvesting and processing
122
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Tab\e 4-3. Resufts of Pesticide Residue Sampling in Cotton From Growing Regions Worldwide (4)
Source
Argentina
Argentina
Australia
Columbia Acala
Cote d'lvoire
Greece
Israel
Mali
Mexico
Mexico-Mante
Paraguay
Peru del Cerro
Peru-Pima
Sudan-Rahad Acala sg
Sudan-Shambat
Syria
Tadzhikistan ELS rg
Chad
Turkey
Turkey
Turkey Hatay
Turkmenistan
Turkmenistan ELS rg
United States: Arizona
United States: California
United States: MOT
United States: Pima
United States: Pima
United States: Texas
Uzbekistan
Uzbekistan ELS rg
Zimbabwe Albar
Zimbabwe Delmac rg
Total
DDTs
(1.0000)
a
—
0.031
—
—
0.037
—
0.014
—
—
0.041
0.009
0.075
—
—
—
0.046
—
—
0.027
—
—
0.059
—
—
—
—
—
0.008
—
—
0.019
0.008
Pesticide
(TLV for vegetable foodstuffs in mg/kg)
Lindan HCB Qunitozen Dicofol Methoxychlor Endosulfan Tetradifon
(0.5000) (0.1000) (1.0000) (2.0000) (10.0000) (30.0000) (1.5000)
0.004 — — — — — —
0.002 — — — — — —
0.002 — — — — — —
0.002 — — • — — — 0.024
_ _ _ _ _ — —
0.005 — — — , — — —
0.006 — — 0.022 0.168 — —
0.002 — — — — — —
_ _ _ _ _ _ _
_ _ _ _ _ _ _
0.002 — — — — — —
0.003 — — — " — — —
0.002 — 0.002 — — — —
0.001 — — — , — — —
0.002 — — — — 0.107 —
0.003 — — — — . . — —
_ _ _ _ • _ - _ _
0.002 — — — — — —
0.004 — — — __ _
0.004 — 0.006 — — — —
0.003 — — — — 0.02 —
_ _ _ _ — - —
_ _.._ ._ _ ._ _.
0.0008 0.0002 — — — — —
0.006 — — — — — —
0.004 — — — — —
0.005 — — — — — —
0.0007 — — — — — —
0.0007' 0.0003 — — — — — -
0.004 — — — — — —
— . ' — — — — — —
_ _ ' _ ' _ _ _ _
0.003 — 0.006 — — — —
Total
Limit MST
(1.0000)
0.0040
0.0020
0.0330
0.0260
0.0000
0.0420
0.1960
0.1600
0.0000
0.0000
0.4300
0.1200
0.0790
0.0010
0.1090
0.0030
0.0460
0.0020
0.0040
0.0370
0.0230
0.0000
0.0590
0.0010
0.0006
0.0040
0.0050
0.0007
0.0018
0.0040
0.0000
0.0190
0.0170
1 Not detected.
1993 and reported by the Bremen Cotton Exchange in
Germany, however, reported only trace levels of pesti-
cides in cotton samples from around the world, including
the United States (see Table 4-3). All these levels were
below the threshold limit value (TLV) for foodstuffs, and
they represent little concern, unless an agricultural pro-
duction upset or spill occurs (4).
Analysis of raw cotton fiber indicates the presence of
high BOD and COD, as well as copper, tin, and zinc.
Table 4-4 shows the levels of these pollutants in both
Delta and California cottons (5). Tests for other metals,
including arsenic, cadmium, chromium, mercury, lead,
selenium, and titanium, found them all to be below ICP
detection limits. German testing found most metals to be
123
-------
nondetectable, with the exception of zinc, which was still
below the "pollutant-free certification" limit (4).
Smith and Rucker (6) reported on a series of tests
involving neutron activation of different cotton samples.
The following metals were present in cotton fibers after
the fibers are spun, woven, and prepared: titanium,
manganese, magnesium, copper, vanadium, aluminum,
chromium, cesium, zinc, and cobalt (see Table 4-5).
Studies of processing solutions in textile operations (6)
have also shown that the metal content (iron, copper,
zinc, and manganese) in these solutions exceeds the
metal content in raw water (see Table 4-6). Fibers or
previously added materials (e.g., warp sizes) introduce
these metals into the processing solutions.
Reducing or eliminating metal contaminants in cotton
processing wastewater involves testing incoming fibers
and avoiding use of those contaminated with metals.
Tablo 4-4. Presence of BOD, COD, and Metals In Cottons (5)
Pollutant In Extract
BOD
COD
Copper (Cu)
Tin (Sn)
Zinc (Zn)
Delta Cotton
(ppm)
514
956
0.048
0.003
0.323
California Cotton
(ppm)
848
1,693
0.050
Not detected
0.315
Table 4-5. Metals Present In Prepared Cotton (6)
Metal Sample I (ppm) Sample II (ppm)
Titanium (Ti)
Manganese (Mn)
Magnesium (Mg)
Copper (Cu)
Vanadium (V)
Aluminum (AI)
Chromium (Cr)
Cesium (Cs)
Zinc (Zn)
Cobalt (Co)
2.11
0.140
1.632
2.29
0.070
33.91
0.095
0.0076
7.38
0.017
<0.5
0.104
1.741
3.16
0.032
29.45
0.142
0.0083
7.35
0.0024
Table 4-6. Metals Content of Raw Water and Textile
Processing Solution (6)
Average Raw Water Average Processing Solution
Metal Concentration (ppm) Concentration (ppm)
Fa
Cu
Zn
Mn
0.1
0.02
0.11
0.01
1.5
0.25
1.49
0.03
This requires a global pollution prevention approach not
usually seen in textiles. The spinning mill should perform
the incoming QC step to eliminate metals in effluent from
the finishing mill. Elements of such an approach are
discussed further in Section 4.17, "Globalization of Pol-
lution Prevention."
4.2.1.2 Wool
Wool is another significant commercial natural fiber. The
main concerns with wool processing are FOG and
aquatic toxicity arising from pesticide residues on raw
wool. Pesticides are applied directly to sheep to reduce
parasitic infestation, and these residues are released
into wool-processing wastewater during preparation and
dyeing (7).
Wimbush (8) reported that a specific agricultural resi-
due, pentachlorophenol (PCP), was found at levels as
high as 100 parts per million (ppm) in consumer prod-
ucts such as wool carpets. PCP causes indoor air pol-
lution and respiratory distress in humans and pets.
Because of the lipophilic nature of chloro-organic pesti-
cides such as PCP, they tend to become associated with
natural oils in the wool and are removed with those oils
in wool scouring operations (7).1 Several alternative
pesticides can be used in place of PCP, but all have
negative consequences for downstream waters (7).
Harmful PCP levels in consumer textile products are, in
some cases, too low to be quantified accurately using
traditional methods. In a test of 140 wool carpets, Wim-
bush (8) found that 123 (88 percent) had a PCP content
below 5 ppm. Of the remainder, 3 were in the 5- to
10-ppm range, 11 were in the 11- to 50-ppm range, and
3 contained more than 50 ppm.
Careful prescreening of raw wool fibers for PCP resi-
dues is necessary. Interestingly, in carpets with high
PCP levels, PCP was found primarily in the jute or
polypropylene backings, not in the wool pile. Of 28 raw
wool fiber samples from carpet, 19 had measured levels
of PCP below 5 ppm and none had levels above 50 ppm
(see Table 4-7). When 81 samples of carpet material
other than raw wool were tested (e.g., jute, cotton,
polypropylene, latex carpet components), 19 of 81 sam-
ples had PCP levels above 5 ppm and 10 had levels
above 50 ppm (see Table 4-8).
Sampling data suggest that some countries are more
knowledgeable about the effects of PCP and thus more
restrained in the use of these chloro-organic pesticides.
Shaw (7) sampled wool from the countries responsible
11n some cases, lanolin, which is used in cosmetics, can be removed
from the scoured-off oils (7). Chloro-organic pesticide residues in
the oils, however, can render the recovered lanolin, and other oils
from the wool, unsuitable for cosmetic use (7). Lanolin refiners have
found ways to remove the pesticides to levels below 1 ppm, but even
that level is undesirable in consumer skin care products.
124
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Table 4-7. PCP Levels in Wool Carpet (8)
POP Level (ppm) Number of Samples (%)
<5
5 to 50
>50
Total sampled
19 (68)
9 (32)
0 (0)
28 (100)
Table 4-8. PCP Levels in Carpet Components Other Than
Wool (7)
PCP Level
<5 ppm
5 to 50 ppm
>50 ppm
Total Sampled
Number of Samples (%)
62 (77)
9 (11)
10 (12)
81 (100)
Table 4-9. Organochloride Pesticide Levels Detected in
Samples From Different Wool-Producing
Regions (9)
Country of Origin
Average Level! Detected (ppm)
Australia
Europe
New Zealand
South Africa
South America
0.091
4.46
0.01
3.19
162.5
for most of the world's raw wool production and found
the highest chloro-organic pesticide levels in South
American wools (see Table 4-9). Wools from Australia
and New Zealand exhibited the lowest levels. Many
countries have adopted regulatory controls on the use
of chloro-organic pesticides, and in those countries pes-
ticide levels in rivers that run through sheep-producing
areas have dropped by more than 50 percent (7).
Because of the extremely high variability of pesticide
residues in raw wool, a comprehensive raw material
testing protocol is necessary for pollution prevention.
Industry standards, such as the Woolmark carpet certi-
fication system, have been set up to require proper raw
material prescreening. This certification system requires
that all incoming raw materials be tested to ensure that
they do not contain PCP above the regulatory level or 5
ppm. To receive the Woolmark certification, all raw ma-
terials must pass this test.
To aid in the detection of PCP, several rapid, effective
HPLC analytical procedures for testing raw wool and other
carpet components for PCP have been developed. These
tests replaced more time-consuming, less sensitive tests.
HPLC has high sensitivity and the equipment, although
not part of a standard textile mill laboratory, is readily
available in most areas. This technique allows testing of
many samples fairly quickly and inexpensively (7).
4.2.2 Synthetic and Regenerated Fibers
Synthetic and regenerated fibers comprise a wide vari-
ety of manmade fibers, as well as some regenerated
natural fibers. These are shown in Table 4-10.
Synthetic fibers may contain several types of impurities
that are imparted to the fibers during fiber manufactur-
ing. These impurities exist in the fibers before they reach
the textile manufacturer and fall into the categories of
finishes, polymer synthetic by-products, and additives.
Table 4-11 lists some of these contaminants.
Table 4-10. Synthetic and Regenerated Fibers
Synthetic Regenerated
Acetate
Triacetate
Acrylic
Aramid
Modacrylic
Polyamide (nylon)
Polyethylene
Polypropylene
Polyester
Saran
Spandex
Rayon
Viscose
Rubber
Chitin
Chitosan
The three main concerns associated with wet process-
ing of fibers contaminated with impurities are:
• Aquatic toxicity
• Metals
• BOD and COD
Smith (10) tested several textile mill effluents which
showed significant aquatic toxicity, and identified many
organic compounds and metals. In another, study (5)
many of the same organic compounds, as well as sev-
eral metals (As, Cd, Cr, Cu, Hg, Pb, Se, Ti, and Zn), were
identified in synthetic fiber extracts. These organic com-
pounds (of varying toxicity), which were identified in mill
effluents and also in fiber extracts, are listed by fiber
type in Table 4-11. The synthetic fiber extracts also
exhibited high BOD and COD as shown in Table 4-12.
In the preceding table, the COD:BOD ratio of the acrylic
extract is very high, indicating the potential for pass-through
during treatment and subsequent discharge to the envi-
ronment. At this time, no toxicity data exist for these
extracts, but tests are underway (5).
Many impurities found in synthetic and regenerated fi-
bers are intentionally applied as part of proprietary spin
finishes. These finishes are added to fibers for lubrica-
tion and to impart other desirable properties such as
125
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Tablo 4-11. Impurities Associated With Synthetic Fibers
Finishes
Antistatic
Lubricant
Polymer Synthesis By-Products
Unreactod monomers
Low-molecutar-welght oligomers
(e.g., trimer)
Residual catalyst
Additives To Facilitate Processing
Antistatic agents
Lubricants
Humsctant
Others
Tablo 4-12. Contaminant Levels In Synthetic Fiber
Extracts (11)
Fiber Extract
COD (ppm> BOD (ppm) BOD/COD
Acrylic
Dacron polyester
Nylon
Trivora polyester
Wool
1,139
271
6,417
319
13,470
155
88
1,803
92
3,322
7.3
3.1
3.6
3.5
4.1
static electricity control. In almost all cases, the finishes
must be removed to ensure uniform penetration of the
fabric by dyes and other finishes and to avoid reaction
or precipitation with dyes and finishes. If left on the fiber,
volatile components of spin finishes can produce toxic
air emissions when vaporized by high-temperature proc-
esses such as drying, heatsetting, thermofixation, and
curing ovens. To prevent these emissions, spin finishes
must be scoured from fibers before dyeing and finishing.
Although this scouring process eliminates the air pollu-
tion problem, it replaces it with a water pollution problem
because the scouring water is ultimately discharged into
the wastewater.
The compounds in Table 4-13 are found not only in
process wastewater from synthetic fiber dyeing and fin-
ishing operations, but also were detected in synthetic
fiber extracts (5,10). Metals extracted from synthetic fibers
are shown in Table 4-14 and include As, Cr, Cu, Pb, and
Zn. Not all of these were detected in all four synthetic
fiber types tested. Only Cu and Zn were detected in the
Trivera and acrylic samples; Cu, Pb, and Zn were pre-
sent in the Nylon 6 samples; while As, Cr, Cu, and Zn
were detected in the Dacron sample (5).
4.2.3 Pollution Prevention Strategies
The above review of pollution problems illustrates the
potential benefits of incoming fiber QC and greater dis-
closure of potentially harmful impurities and additives
Table 4-13. Compounds Typical of Synthetic Fiber Extracts
Dacron
Tetra hydro 2,5 dimethyl cis furan
Methyl isobutyl ketone
3 methyl cyclo pentanone
Hexanone
Diethyl ketone
Dodecanol
Alcohols (C|4 and C18)
Esters of CM - C24 carboxylic acids
Hydrocarbons (C-u - CB)
Carboxylic acids (Q6 - C24)
Phthalate esters (many)
Trivera
Tetra hydro 2,5 dimethyl cis furan
Ketones (several similar to Dacron above)
Alcohols (Cia - Cis)
Carboxylic acids (Ci2 - C18)
Esters of carboxylic acids (C12 -
Phthalate esters (several)
Hydrocarbons
Acrylic
Hydrocarbons (several C15 -
Esters of carboxylic acids (C^ - C22)
Alcohols
Phthalate esters
N,N dimethyl acetamide
Other nitrogenous compounds
• Nylon 6
Diphenyl ether
Hydrocarbons (C-is - C2o)
Carboxylic acids (C14 - Ci8) and
dicarboxylic acids
Esters of carboxylic acids (Cio -
Alcohols (C2o - C22)
Other nitrogenous compounds
Table 4-14. Metals Concentrations in Extracts From Synthetic
Fibers (ppm) (5)
Fiber
Trivera
Dacron
Acrylic
Nylon 6
As
bdla
0.061
bdl
bdl
Cr
bdl
0.011
bdl
bdl
Metal
Cu
0.033
0.03
0.025
0.034
Pb
bdl
bdl
bdl
0.01
Zn
0.117
0.075
0.087
0.148
a bdl = below detection limit of ICP.
(i.e., spin finishes). Many fiber contaminants are metals
and organics, which are undesirable in wastewater and
can cause air pollution. Some of these impurities are
produced during polymerization of synthetic fibers, while
others are intentionally added to control the surface and
electrical properties of fibers. Many of these impurities
126
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can interfere with downstream processing and quality,
and create pollution problems.
Because of the extremely high volume of fibers used
in textile processing and the great variability in contami-
nation, a comprehensive incoming fiber QC program is
essential for synthetics. Some fiber companies, notably
Cotton Incorporated, have endorsed standard testing
methods for fibers and have actively worked to ensure
that the fiber user and the producer (farmer) exchange
information for QC. In synthetics, such global pollution
prevention efforts have not yet evolved. Mills can still
set up good incoming fiber QC, however, based on
performance testing, statistical sampling, and analysis
of extractable materials to identify potential pollution
problems before they arise. Purchasing specifications
should include specific requirements for factors such as
metals, aquatic toxicity, and extractables (e.g., spin fin-
ish levels), as well as specific packaging requirements
to reduce solid wastes (see Section 1.2.3, "Solid
Wastes," for a discussion of fiber packaging materials).
4.3 Dyes
The following table introduces pollutants and waste
streams discussed in this section, as well as pollution
prevention activities suggested for each.
Pollutant or Waste
Stream
Pollution Prevention
Actions Described
in This Section
Comments
Pollutant or Waste
Stream
Pollution Prevention
Actions Described
in This Section
Comments
4.3, Dyes (General)
Color
Aquatic toxicity
Metals
Undesirable degrada-
tion residues
Packaging
Obsolete dyes
General
Proper dye selection,
optimization of
handling, optimization
of dye process for
maximum dye
exhaust in batch
dyeing, improved
audit and employee
training for identified
dyes
Identifying toxic dyes
and providing special
handling, worker
training, auditing, spill
response/control
Dye selection,
handling
Dye selection,
handling
Using IBCs or
returnable containers
Proper inventory
control
Involving dye
vendor/supplier in
pollution prevention
activities at the mill
level
Insist on
identification and
disclosure of
environmental
information on dyes
4.3.1, General Background
General
Salt
Wastewater (high
volume of water)
Color
Metals
Air emissions
Properly inform dyers
and dye handlers
concerning the
technical aspects of
dye use
Select cotton dyes
that require minimum
amounts of salt, and
optimize salt for each
recipe
Optimize dyeing and
washing operations
Proper dye selection
Optimum handling,
auditing, and
employee training
Optimization of dye
process for maximum
dye exhaust in batch
dyeing
Dye selection,
handling
Auxiliary chemical
selection and handling
Optimum process
and drying conditions
Vendor/supplier
must be involved
to provide
information for
proprietary products
See dyeing (see
Section 4.10 for
further information)
4.3.2, Dyes and Dye Processes
Water
Salt
Metals
Color
Organic chemical
wastes from spent
chemical dyeing
auxiliaries
Equipment
maintenance,
employee training,
process optimization,
waste stream
segregation for
reuse and many
other methods
of water
conservation
Selecting cotton
dyes that require
minimum amounts
of salt, and
optimizing salt
for each recipe
Dye selection,
handling
Optimum handling,
proper dye selec-
tion, optimum dye
process for
maximum dye
exhaust in batch
dyeing
Process optimiza-
tion, chemicals
selection, substitu-
tion of "better"
chemicals, process
modification to
eliminate the need ,
for chemicals,
alternate processes
Very high hydraulic
loads result from
dyeing and
especially
afterwashing
No general, across-
the-board method
of color treatment
exists, so pollution
prevention is very
important
See also Section
4.5, which gives
more detail on
chemical selection
and use
127
-------
Pollutant or Waste
Stream
Pollution Prevention
Actions Described
In This Section
Comments
Air omissions Process optimiza- Highly dependent
tion, chemicals on the type of
selection, substt- dyeing process
tutton of less volatile
chemicals, process
modification to
eliminate the
need for volatile
chemicals, alternate
processes
4,3.3 through 4.3.3.10, Applications Classes of Dyes
Dyestuff wastes with
associated color, met-
als, aquatic toxicity,
etc.
Better understanding
of batch dyeing
processes
4.3.4, End-Use Classes of Dyes
Dyestuff wastes with Dye selection,
associated color, met- handling
als, aquatic toxicity,
etc.
4.3.5, Environmental Classes of Dyes
Dyestuff wastes with Dye design and
associated color, met- selection
als, aquatic toxicity,
etc.
Dye selection,
framed in the
perspective of the
role of affinity and
reactivity, with
comparisons of
alternative dye
classes
Dye selection in
this section is
framed in the
perspective of end-
use (design)
product
specification
Dye selection in
this section is
framed in the
perspective of the
chemistry of the
dye and the
intermediates from
which it is
synthesized (i.e.,
the design of the
dye itself)
4.3.6, Pollution Prevention for Dyes
Dyestuff wastes with Raw material
associated color, met- prescreening
als, aquatic toxicity, procedures
etc.
Significant opportunities exist for preventing pollution in
textile dyeing operations. This section describes important
characteristics of textile dyes that relate to pollution pre-
vention and serves as background to other sections of this
document (e.g., Section 4.10, "Dyeing"). In addition, this
section presents pollution prevention strategies for use in
selecting dyes, evaluating dye alternatives, and modifying
work practices. The following list summarizes briefly the
main pollution prevention ideas presented in this section.
• Handle and use all dyes in a conservative manner.
• Arrange processes to ensure maximum dye exhaust
and fixation, and minimum waste from spent process-
ing baths.
• Always deal with suppliers who are knowledgeable
and responsible/reputable.
• Prescreen all dyes before use by reviewing all avail-
able environmental information.
• Insist that suppliers identify all dyes and provide in-
formation on their environmental fate and impacts.
Avoid using dyes if inadequate information exists about
their safety, metal content, degradability, or safety of
the aerobic and anaerobic degradation products.
• Identify dyes that are highly toxic, metal bearing, etc.
Establish procedures for proper handling and spill
response, and train workers.
• Inform designers, schedulers, and customers of the
environmental burden of problem dyes, and recom-
mend safer alternatives. Those involved in specifying
colors and hues may not realize environmental con-
sequences of their choices.
• Understand the application classes and subclasses
of dyes, and use this information as well as an un-
derstanding of site-specific features and limitations
(e.g., equipment, control systems, and facility layout)
to design efficient processes.
• Select dyes with the highest fixation efficiency.
• For exhaust dyeing, select dyes with high affinity, if
possible, especially where the bath ratio of the dyeing
equipment is high.
• Select dyes and dye combinations with the highest
probability of right-first-time dyeing in the specific use
setting.
• Perform statistical sampling and routine dye quality
control checks to ensure environmental quality and
. performance.
• Keep in mind that pollution prevention extends to
both dye selection and dye process operation. Fur-
ther information on dye process considerations,
found in Section 4.10, "Dyeing," should be reviewed.
4.3.1 General Background
Textiles are dyed using a wide range of dyestuffs, tech-
niques, and equipment. Most dyeing is performed either
by the finishing division of vertically integrated textile
companies, or by specialty dyehouses that operate on
a commission basis or that purchase greige goods and
finish them before selling them to apparel and other
product manufacturers. Dyes used by the textile industry
are largely synthetic and are derived from coal tar and
petroleum-based intermediates. Some naturally occur-
ring dyes, derived from animal or plant sources, are also
used but are relatively unimportant commercially. Most
dyes are considered chemical specialties because of
their low volume and high price, although a significant
128
-------
proportion are produced in commodity volumes. Dyes
are sold as powders, granules, pastes, and liquid dis-
persions and solutions, with concentrations of active
ingredients ranging typically from 20 to 80 percent.
Dyes are applied to fibers or fabrics in a variety of ways
and impart their color via different mechanisms, which
are described below. A variety of auxiliary chemicals are
used during dyeing to assist in dye absorption and
fixation into the fibers.
Important factors in dye selection include type of fiber
and machine, product end-use application, and cus-
tomer demands or preferences. Historically, the environ-
mental impact of dye selection, application, and use has
not been a major consideration. Until recently, dyers had
little access to information concerning the environmental
impact of dyes, and as of 1984, the chemical composi-
tion of at least half the dyes used in the industry was
estimated to be unknown (12). During the last 40 years,
however, more information on the environmental conse-
quences of dyes has become available, and dye manu-
facturers have substantially eliminated hazardous dyes
from their product lines while actively searching for safer
substitutes. To the extent that more environmentally
benign dyes are consistent with customer needs and
product quality, dye manufacturers seek to offer dyes
that provide water and energy savings, reduce pollution,
and increase efficiency in dye and chemical use as well
as raise productivity.
Dye use presents several environmental concerns that
should be addressed through pollution prevention:
• Dyeing operations are water-intensive.
• Cellulose dyeing uses massive amounts of salt.
• Dyes contain metals such as copper, nickel, chro-
mium, mercury, and cobalt. In some dyes, these met-
als are functional (i.e., they form an integral part of
the dye molecule); however, in most dyes, metals are
present as impurities (see Section 2.2.5, "Metals").
For example, mercury is used as a catalyst in the
manufacture of certain dyes and is often present as
a trace residue. Metals are difficult to remove from
wastewater and may pass through the effluent treat-
ment system or become part of the wastewater sludge.
• Water from spent dyebaths and dye rinse operations
contains unreacted or unfixed dyes, and effluent dis-
charge containing these compounds may be highly
colored. Because color can interfere with the trans-
mission of light in receiving waters, high doses of
color can interrupt photosynthesis and aquatic life.
Color can also interfere with ultraviolet (UV) disinfec-
tion of treated wastewater. The primary concern
about effluent color at discharge concentrations, how-
ever, is its undesirable aesthetic impact on receiving
waters. Aesthetic concerns about textile mill effluent
have led to increased regulatory attention at the local
level.
• Dye rinse water and spent dyebaths contain numerous
auxiliary chemicals, such as salt. Important individual
chemicals contained in these wastes are addressed in
other sections of this document (e.g., Sections 2.2.2, "Dis-
charge of Electrolytes," 4.4, "Chemical Commodities," 4.5,
"Chemical Specialties," and 4.7, "Slashing and Sizing").
• Dyeing contributes to air emissions, although air con-
cerns are related more to the types of dyeing processes
and to the chemical auxiliaries used than to the specific
dyes selected. For example, batch dyeing of disperse
dyes may be performed on atmospheric machines that
operate with the aid of dye carriers. These carriers in-
clude aqueous emulsions of chemicals that may volatilize
during subsequent heatsetting, drying, or curing stages.
4.3.2 Dyes and Dye Processes
Textiles are dyed using batch and continuous processes.
In batch dyeing, a certain amount of textile substrate,
usually 100 to 1,000 kilograms, is loaded into a dyeing
machine and brought to equilibrium, or near equilibrium,
with a solution containing the dye. Because the dyes
have an affinity for the fibers, the dye molecules leave
the dye solution and enter the fibers over a period of
minutes to hours. Auxiliary chemicals and controlled
dyebath conditions (mainly temperature) accelerate and
optimize the action. The dye is fixed in the fiber using
heat and/or chemicals, and the tinted textile substrate is
washed to remove unfixed dyes and chemicals.
In continuous dyeing processes, textiles are fed continu-
ously into a dye range at speeds usually between 50
and 250 meters per minute. To be economical, this may
require the dyer to process 10,000 meters of textiles or
more per color, although specialty ranges are now being
designed to run as little as 2,000 meters economically.
Continuous dyeing processes typically consist of dye
application, dye fixation with chemicals or heat, and
washing. Dye fixation on the fiber occurs much more
rapidly in continuous dying than in batch dyeing.
In batch dyeing, the objective is maximum exhaust and
fixation of the dye to minimize carryover of unfixed dye
into the washing stages. The maximum dye exhaust
achievable is related to the affinity of the dye for the fiber
and the bath ratio, as expressed in the following (13):
= K/(K + L)
(Eq. 4-1 )
where:
E = exhaust, which ranges from 0.50 to 1.00 (50- to
100-percent exhaustion) in commercial
operations (14)
K = dye affinity, which ranges from 50 to 1,000 for
various dye/fiber combinations
129
-------
L » bath ratio, which ranges from 5 to 50 for
various machines2
(See Figure 4-1.)
In the following expression, K is a partition coefficient,
the ratio of the concentration of dye in solution to the
concentration of dye in the substrate at equilibrium, i.e.,
K = cf/cs (Eq. 4-2)
where:
c1 = concentration of dye in fiber at equilibrium
c3 = concentration of dye in solution at equilibrium
According to Equation 1, when the bath ratio increases,
exhaustion decreases and more color is discharged.
This effect is more pronounced with low affinity dyes
(i.e., when K is low). When K decreases, more dye
2 Note that affinity is based on equilibrium concentrations wheras
exhaust Is based on amounts or mass of dye. Therefore, K (affinity)
does not depend on L, but E (exhaust) does.
3 When dealing with fiber reactive dyes, however, hydrolysis does not
significantly effect affinity. High affinity hydrolyzed dye is difficult to
wash off. Susceptability to hydrolysis is a factor regarding color in
the wastewater for fiber reactive dyes.
remains in the solution and the color in the wastewater
increases, especially if L is high. This highlights the
importance of affinity. To reduce color in wastewater, the
dyer should select higher affinity dyes (i.e., with high K
values). When running low affinity (low K) dyes, short
bath ratios are essential.3
Different dye classes exhibit different affinities depend-
ing on the type of fiber. Even within dye classes, individ-
ual dyes can show large affinity variations. Thus,
generalizing about exhaustion associated with specific
dye classes, and especially with specific dyes, is difficult.
Dye vendors, however, can identify the higher affinity
class members for dyers. With this caveat in mind, some
typical exhaustion/fixation levels for various dye classes
are given in Table 4-15.
As shown in the table, users of cellulose dyes have
the greatest problems with poor exhaustion and fixa-
tion characteristics. Further, the popular fiber reac-
tive dyes lead the list in terms of poor fixation,
except for recently introduced, improved reactive
dyes for cotton, which exhibit a higher degree of
fixation. The same conclusions are reflected in
Examples:
Basic Dyes K = 700
Rber Reactive K = 50
Beck L= 17
Garment Dyeing L = 50
A. Basic on Garment
B.Basic on Becks
C. Fiber Reactive on Garment
D. Fiber Reactive on Becks
Figure 4-1. Relationship between dye exhaust and affinity.
130
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Table 4-16, which presents data on color values for
approximately 20 different combinations of dyes, fibers,
and dye machines.
Although much information in this section concerns
batch dyeing, continuous dyeing also has specific dye
requirements. In general, dyes with low affinity are fa-
vored in continuous dyeing for two reasons:
• To prevent "tailing" from occurring during a run. Tail-
ing is often attributed to undesirable exhaustion of
the padding solution.
• To make washing off the unfixed color easier.
Easy washoff is essential in continuous dyeing. Dyes
with low affinity, by definition, wash off more easily (if not
fixed). To achieve consistent shade repeats and level
(even) dyeings, each dye in a recipe must have applica-
tion properties (i.e., fixation rate) similar to all other dyes
in the recipe.
Some dyes are sensitive to specific water contaminants
(e.g., hardness, iron, copper, chlorine, tannic acid, and
Table 4-15. Exhaustion/Fixation Levels for Various Dye
Classes (14)
Class
Typical
Typical Ka Fixation {%) Fibers
Acid
Azoic
Basic
Direct
Disperse
Premets
Reactive
Sulfur
Vat
130
200
700
100
120
470
50
50
130
80 to 93
90 to 95
97 to 98
70 to 95
80 to 92
95 to 98
50 to 80
60 to 70
80 to 95
Wool
Cellulose
Acrylic
Cellulose
Synthetic
Wool
Cellulose
Cellulose
Cellulose
The typical K is computed by assuming a bath ratio of 17:1 (typical
for becks) and solving for K = EL/(1-E), where E is on a O-to-1 scale.
For acid dyes, the dye exhausted is typically 87 percent, or E =
0.87. Solving E = K/(K + L) for K results in K = L/(H - E) =-(17)/(0.13)
or 130. Therefore, at equilibrium the concentration of dye in the fiber
will be 130 times greater than the concentration of dye in the bath
for a dye that exhausts 87 percent at 17:1 bath ratio.
Table 4-16. Wastewater Color Values From Various Dye/Substrate/Dye Method Combinations (15)
Dyeing
No. Dye Class
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Vat
2:1 Premetallized
Disperse
After coppered direct
Reactive
Disperse
Chrome
Basic
Disperse
Acid
Direct
Developed
Disperse/Acid/Basic
Disperse
Sulfur
Reactive
Vat/Disperse
Basic
Disperse/Acid/Basic
Azoic
Substrate
Cotton
Poiyamide
Polyester
Cotton
Cotton
Poiyamide carpet
Wool
Polyacrylic
Polyester carpet
Poiyamide
Rayon
Rayon
Poiyamide carpeit
Polyester
Cotton
Cotton
Cotton/polyester
Polyester
Polamide carpet
Cotton
Method
Exhaust/Package
Exhaust/Beck
AtmosVExhaust
Exhaust/Beck
Exhaust/Beck
Exhaust/Beck
Exhaust/Beck
Exhaust/Beck
Exhaust/Beck
Exhaust/Beck
Exhaust/Beck
Exhaust/Beck
Exhaust/Beck
High-Temperature
Exhaust
Continuous
Continuous
Continuous
Atmospheric/
Exhaust
Continous/Kuster
Exhaust/Package
Apparent
ADMIa ADMI
Color Color
1,910 —
370 —
315 —
525 1,280
3,890 —
100 —
3,200 —
5,600 12,000
215 315
4,000 —
12,500 —
2,730 —
210 720
1,245 —
450 —
1,390 —
365 1,100
1,300 . 2,040
<50 190
2,415 —
TOC
(mg/L)
265
400
300
135
150
130
210
255
240
315
140
55
130
360
400
230
350
1,120
160
170
BOD
(mg/L)
294
570
234
87
INT°
78
135
210
159
240
15
12
42
198
990
102
360
1,470
130
200
PH
12
7
8
5
11
8
4
5
7
5
7
3
7
10
4
9
10
5
7
9
Sus-
pended
Cr Solids
(mg/L) (mg/L)
190
nil
33
520
9,800
28
33
27
27
14
61
130
10
1,680
42
57
167
17
22
7,630
41
5
39
41
32
14
9
13
101
14
26
13
8
76
34
9
27
4
49
387
Dissolved
Solids
(mg/L)b
3,945
1,750
914
2,763
12,500
395
1,086
1,469
771
2,028
2,669
9.8
450
1,700
2,000
691
2,292
1,360
258
10,900
ADMI = American Dye Manufacturers Institute.
'Mostly salt.
: INT = high salt or reactive.
131
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aluminum) (11). This is a significant consideration be-
cause background levels of these contaminants in proc-
ess water fluctuate considerably from season to season,
location to location, and mill to mill. Different mills that
produce a similar product in two different locations, or at
different times of the year, sometimes use different dyes
and dyeing methods to account for variations in water
quality.
4.3.3 Characteristics of Dyes
Textiles are dyed using many different colorants, which
may be classified in several ways (e.g., according to
chemical constitution, application class, end-use). The
primary classification of dyes is based on the fibers to
which they can be applied, and the chemical nature of
each dye determines the fibers for which the dye has
affinity. Table 4-17 lists the major dye classes and the
types of fibers for which they have an affinity. The dye
classes commonly used in the textile industry are de-
scribed in further detail below.
4.3.3.1 Acid Dyes
Acid dyes are water-soluble anionic compounds applied
to nylon, wool, silk, and some modified acrylic textiles in
an acidic medium. Some acid dyes are also used for
coloring food and paper. They exhibit little affinity for
cellulosic or polyester fiber. Colors generally are bright,
and the material exhibits good to excellent fastness
properties. Acid dyes have one or more sulfonic or
carboxylic acid groups in their molecular structure. The
dye-fiber affinity is the result of ionic bonds between the
Table 4-17. Dye Classes and Fibers for Which They Have
Affinity
Dyo Class
Fibers
Acid
Azoic
Basic
Direct
Disperse
Fiber reactive
Food dyes
Mordant (obsolete)
Naphtid (azoic)
Optical brighteners
Pigment
Solvent
Sulfur
Vat
Wool and nylon (polyamide)
Cotton and cellulose (see naphthol)
Acrylic, certain polyesters
Cotton, rayon, and other cellulosic
Polyester, acetate, and other synthetics
Cotton and other cellulosic, wool
Not used in textiles, similar to acid dyes
Natural fibers (must pretreat with metals)
Cotton, rayon, and other cellulosic
Various (also called fluorescent
brighteners)
All (requires binders, just like painting)
Synthetic, rarely used in commerce
Cotton and other cellulosic
Cotton and other cellulosic
sulfonic acid part of the dye and the basic amino groups
in wool, silk, and nylon fibers.
Mordants can be used to improve wetfastness and per-
spiration fastness of acid dyes, although shades tend to
be duller. Mordants include Cr, Sn, Cu, and Al. Because
of environmental concerns surrounding mordants, their
use in acid dyeing in the United States has essentially
ceased.
4.3.3.2 Azoic Dyes
Azoic dyes, also known as naphthol dyes, are used on
cellulosic fibers (particularly cotton) but may also be
applied to rayon, cellulose acetate, linen, jute, hemp,
and sometimes polyester. Azoic dyes are made up of
two chemically reactive compounds, which are applied
to the fabric in a two-stage process. The reaction of the
two compounds in the fiber produce the colored azo
chromophore. During dyeing, the azoic dye forms inside
the fibers.
The Colour Index (Cl) refers to the components used in
azoic dyeing as Cl Azoic Coupling Components and Cl
Azoic Diazo Components. The coupling components
are mostly derived from p-naphthol and are available in
powder or liquid form, while the diazo components are
available as free bases (fast color bases) and diazonium
salts (fast color salts). The depth of shade is determined
by the extent to which the coupling component is ab-
sorbed when the diazo component is applied to the fiber.
Azoic dyes produce bright and dark shades of yellow,
orange, red, maroon, navy blue, brown, and black. The
dyes exhibit good lightfastness and fastness to peroxide
and other bleaches. They can be applied in a variety of
ways (i.e., continuously or using yarn, jet, beck, or jig
dyeing processes). Use of azoic dyes has declined over
the years, however, because of application costs and
concerns about the possible presence of carcinogenic
naphthylamines in the effluent.
4.3.3.3 Basic (Cationic) Dyes
Basic dyes were the first synthetically manufactured dye
class. They were initially used to dye silk and wool (using
a mordant), but they exhibited poor fastness properties.
Modified basic dyes were developed and are now used
exclusively to color synthetic fibers such as acrylic, mo-
dacrylic, and modified nylons and polyesters, in which their
fastness is acceptable. Basic dyes are rarely used on
natural fibers, both because of their poor light- and wash-
fastness and because of the need for mordants.
Basic dyes have limited water solubility and are applied
in weakly acidic dyebaths. Ionic bonds are formed be-
tween the cation in the dye and the anionic site on the
fiber. As a class, basic dyes are among the brightest
dyes available. In addition, they have unlimited color
range and good fastness properties (except in natural
132
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fibers, as noted above). Good preparation (scouring) is
necessary to remove the surface additives applied for
knitting and weaving. Basic dyes are strongly bound and
do not migrate easily; therefore, temperature must be used
to carefully control exhaustion to ensure level dyeing.
Basic dyes exhibit high aquatic toxicity, as shown in
Tables 2-28 and 2-29, but when applied properly, they
exhaust nearly 100 percent. Problems are more often
attributable to improper handling procedures, spill
cleanup, and other upsets.
4.3.3.4 Direct Dyes
Direct dyes are water-soluble, anionic compounds used
extensively for coloring paper but also for dyeing cotton,
rayon, linen, jute, hemp, silk, and nylon fibers, as well as
mixtures of fibers and leather. The term "direct dye" refers
to the fact that these dyes can be applied directly to
cellulosics without, mordants. The dyes are absorbed into
hydrophilic fibers as the fibers expand in the water solution.
Sodium chloride or sodium sulfate salts are added to the
dyebath to counteract the slightly negative charge that
cellulosics have in aqueous solution. The molecular struc-
ture of direct dyes is narrow and flat, permitting these
molecules to align with flat cellulose fibrils, where the dye
molecules are held in place through Van der Waals forces
and hydrogen bonds. Fixatives, which react with the dye,
are generally added to hold the dye molecules in place and
improve colorfastness.
Although direct dyes yield bright, deep colors, they vary
greatly in lightfastness. They are widely used to color
cellulosic materials including those that need high fast-
ness (e.g:, upholstery and drapery fabrics). Also, they
are limited in washfastness and their ability to withstand
exposure to moisture (e.g., perspiration) unless the fab-
ric is aftertreated with a chemical fixative in a common
procedure called afterfixing. Direct dyes are more eco-
nomical than reactive or vat dyes, but their use has
declined in recent years as reactives with superior end-
use properties have risen in popularity. They are bene-
ficial from a pollution prevention standpoint, however,
because direct dyes use low amounts of salt and other
offensive materials, compared with reactive dye.
4.3.3.5 Disperse Dyes
Disperse dyes have a very low water solubility, so they
are applied as a dispersion of finely ground powders in
the dyebath. The particles dissolve at low concentra-
tions in the aqueous dyeing medium but transfer into the
synthetic fiber polymer because of their higher solubility
in the substrate. High temperatures and superat-
mospheric pressures are sometimes used for application.
This reduces the need for chemical accelerants (e.g.,
dye carriers), which are required at lower temperature.
Disperse dyes are used for oleophyllic fibers (polyester
and other synthetics) that do not accept water-soluble
dyes. They are used largely for synthetic fibers, mainly
polyester but also cellulose acetate rayon (also called
regenerated cellulose fibers), nylon, and acrylic fibers.
For polyesters, disperse dyes offer a full shade range.
Because of the limited buildup properties and poor
washfastness in dark shades, however, disperse dyes
are used mostly to obtain pastel shades in nylons and
acrylics. Disperse dyes tend to have good fastness to
light, perspiration, laundering, and dry cleaning. They
also have good crocking resistance.
4.3.3.6 Fiber Reactive Dyes
Fiber reactive dyes are water-soluble, anionic dyes that
provide high wetfastness and require relatively simple dye-
ing methods. They are mainly used for dyeing cellulosic
fibers such as cotton and rayon but are also sometimes
used for wool, silk, nylon, and leather. Fiber reactive dyes
have largely replaced direct, azoic, and vat dyes and are
the largest dye class (in commercial value) in the United
States. Because of the bright shades available—particu-
larly orange, scarlet, and turquoise—they are popular
choices for color fashion apparel.
Fiber reactive dyes form covalent chemical bonds with the
fiber and become part of the!fiber, giving excellent fastness
properties. Because of their solubility, leveling takes place
rapidly before fixation, which provides flexibility in dye
application methods. To exhaust the dyes, however, large
amounts of salt are generally necessary, and substantial
amounts of dye can remain unfixed at the end of the
process. After dyeing, the fabric is afterwashed with an
anionic surfactant to remove unreacted dye.
Environmental concerns about fiber reactive dyes focus on
color and salt, two pollutants that are receiving increased
attention. The relatively low fixation efficiency of the dyes
results in effluent color, which is not easily removed in
treatment systems. Decoloration of the effluent is difficult
because of the low level of aerobic biodegradation and/or
adsorption of the dye color onto activated sludge during
treatment. Large amounts of salt are used to exhaust the
dyes, and some jurisdictions are tightening salt limits to
levels that may be difficult to meet because conventional
treatment systems are not effective in removing salt.
Some improvements in fixation of fiber reactive dyes
have been made, ^particularly with the introduction of
bifunctional reactive dyes. Bifunctional dyes have two
reactive groups, which increases the efficiency of dye
fixation. Low-bath-ratio equipment can also be used to
reduce salt requirements, and pad-batch dyeing using
cold reactive dyes that require no sa|t is a viable alter-
native to consider (see Section 4.10, "Dyeing").
133
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4.3.3.7 Mordant Dyes
Mordant dyes are used mainly in wool dyeing, although
they also are used to dye silk and nylon and to print wool,
silk, and cellulosic fibers. In general, mordant dyes have
fair to good fastness properties. These dyes usually con-
tain a ligand functionality capable of reacting strongly with
salts of aluminum, chromium, cobalt, copper, nickel, or iron
to give differently colored metal complexes. Mordants are
now used infrequently in the United States because of
concern about toxic metal salts in the effluent.
4.3.3.8 Pigments
Pigments differ from dyes in that they:
• Remain insoluble during application
• Have no affinity for the fibers
• Require binders
• Do not react with the fibers
Little penetration of the color into the substrate occurs
with pigments. Instead, pigments are usually mixed with
a vehicle that hardens upon drying, forming an opaque
coating. Pigments are used extensively in textile printing
(see Section 4.11, "Printing").
4.3.3.9 Sulfur Dyes
Sulfur dyes are mainly used for dyeing cotton and rayon
substrates. They may also be used for dyeing blends of
cellulosic and synthetic fibers, including nylons and
polyesters, and are occasionally used for dyeing silk.
The synthesis of sulfur dyes is based on the reaction at
high temperature of organic compounds containing nitro
and amino groups with sulfur or sodium sulfide. The
dyes contain sulfur both as an integral part of the chro-
mophore and in polysulfide pendant chains.
Sulfur dyes are reduced with sodium sulfide to a water-
soluble form before application to the fiber. In reduced
form, sulfur dyes are soluble and have an affinity for
cellulose. Sulfur dyes color by absorption, like direct
dyes, but with exposure to air they oxidize to re-form the
original insoluble dye inside the fiber. This makes them
very bleach fast to oxidizing bleaches (e.g., peroxide)
and resistant to removal by washing.
Sulfur dyes have good to excellent washfastness and mod-
erate to good lightfastness. They are relatively inexpensive
compared with other dyes. Although they encompass a
broad shade range, sulfur dyes are mostly used for dark
shades because lighter shades have poorer resistance to
light and laundering. The shade range for sulfur dyes in-
cludes brick reds, browns, burnt oranges, and blacks. Sulfur
dyes tend to be dull compared with other classes. Deep
indigo denim colors are often obtained by applying indigo
dyes over a sulfur "bottom." In recent years, use of sulfur
dyes has decreased in the United States because of
environmental concerns (sulfide residues) associated
with the manufacturing process. Some newer sulfur dye-
ing options, based on low-sulfide reducing agents, are
discussed in Section 4.10, "Dyeing."
4.3.3.10 Vat Dyes
Vat dyes are the oldest and among the more chemically
complex dyestuffs. They are used most often for dyeing
and printing cotton and cellulosic fibers, and for end-uses
that require good fastness properties, such as toweling,
industrial uniforms, military uniforms, and tenting. Although
most commonly used for cottons and cellulosics, they can
also be applied to nylon and polyester/ cellulosic blends
and are sometimes used for dyeing wool and acetate.
Vat dyes have excellent fastness properties when properly
selected and are often used on cotton and cellulosic fab-
rics that will be subjected to severe conditions of washing
and bleaching (e.g., sewing threads). Vat dyes can be
used on all fibers except those sensitive to alkalis.
Vat dyes are applied by exhaust or continuous methods.
They are either supplied in water soluble reduced
"leuco" form or reduced with a reducing agent such as
sodium hydrosulfite. Then they are allowed to migrate
into the fiber by an exhaustion process (for batch dying)
or by steaming (for continuous dyeing). When this mi-
gration into the fiber is complete, the substrate is rinsed
to remove surface dye, then the dye is oxidized back to
its water insoluble form within the fiber. The result is a
dyeing of very high fastness to washing.
Vat dyes offer a good range of colors, but shade ranges
are generally dull.4 Because of this, preparation, includ-
ing bleaching and mercerizing, is important. Mercerizing
helps the dyer achieve deeper shades and produce
adequate cover on raw cotton. Vat dyes are insoluble in
water but are readily soluble in alkaline solution. Vat
dyes can be applied by continuous methods or by ex-
haust dyeing procedures.
4.3.4 End-Use Classes
Dyes are also classified according to their end-use prop-
erties, most notably their fastness under a variety of
end-use conditions, such as light, laundering, crocking,
dry cleaning. These properties, as they relate to the
intended end-use of the textile product, are taken into
account during dye selection by the laboratory dyer, who
formulates the dye recipe for production use.
The consideration of applications, end-uses, and costs
explains why the laboratory dyer selects specific dyes
when matching a particular shade for a customer. Virtu-
ally every shade is custom matched to the exact color
4 Vat dyes can produce bright greens without metals, which is a
problem with other classes for cotton.
134
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the customer requests, although customers generally
have little knowledge of the environmental consequences
of their selections. For maximum pollution prevention, the
dyer should encourage the customer to consider more
environmentally friendly dyes. Often, a slight change in
hue or brightness requirements allows selection of differ-
ent dyes and colorants that could potentially eliminate
significant environmental problems (e.g., metals in waste-
water). This underscores the need for the dyer and the
designer to be aware of both the product and the environ-
mental performance aspects of textile dyes. These globali-
zation issues are discussed further Section 4.17.3.2.
4.3.5 Environmental Classification
Several textile dyes, and even some food dyes, have
been investigated and found to be carcinogenic (16).
Close study of the dyes has revealed that carcinogenic-
ity is linked to specific types of dye intermediates or
metabolites, such as benzidines.
Whaley (12) examined many dyes for evidence of hazard-
ous nature, based on their molecular structure. Of 1,460
dyes examined, the structures were found or known for 585
dyes, or approximately 40 percent of the total. Based on an
assessment of likely reduction degradation products, 55
percent of these known dyes were predicted to be hazard-
ous, and 13 percent were predicted to be uncertain in terms
of safety (see Figure 4.2 for a general overview, and Table
4-18 for a specific breakdown of dyes by color class).
Since 1984, a concerted research effort has been made
to develop dyes based on safer intermediates. Some
safer intermediates, along with the older, traditional mu-
tagenic intermediates, are shown in Figure 4-3. The old
intermediates were adopted many years ago, before
development of the numerous tests now available to de-
termine environmental effects. Responsible dye manufac-
turers have eliminated offending colors from their product
lines; however, the widespread use of apparentfy harm-
ful dyes even as late as the early 1980s indicates the
need for the dyer to be vigilant when selecting dyes and
to use care in handling all dyes.
Responsible manufacturers now consider the environ-
mental impact of the dyes they produce, in addition to their
traditional considerations of economy, high wetfastness,
and high tinctorial value (17). Dyestuffs can be synthe-
sized based on safer intermediates. One strategy for
Total Dyes Examined (1,460)
Known
40% (585)
Unknown
60% (875)
Dyes of Known Structure (585)
Predicted
Safe
32% (186)
Predicted
Hazardous
55% (321)
Uncertain
13% (78)
Figure 4-2. Predicted hazardous nature of dyes (1984).
Table 4-18. Predicted Hazardous Nature of Dyes; All Dyes Except Vats, Sulfurs, Foods, and Brighteners (1984) (12)
Colors
Yellows
Oranges
Reds
Violets
Blues
Greens
Browns
Blacks
Azoics
Totals
Total
Known8
87
54
140
49
98
27
24
35
71
585
Safe
(of Known)
39
15
47
18
41
10
2
9
5
186
Uncertain
(of Known)
16
6
19
7
13
0
1
8
8
78
Hazardous
(of Known)
32
33
74
24
44
17
21
18
58
321
Percent
Hazardous
(of Known)
37
61
53
49
45
63
88
51
82
55
Unknown
190
98
214
40
179
20
94
36
4
875
a Sixty percent of structures were undisclosed and thus could not be evaluated.
135
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Mutagcntc
Nonmutagenic
.OCR,
CHjO
Mutagenlc
Nonmutagenic
CH,
Figure 4-3. Some mutagenlc dye Intermediates and nonmu-
tagenlc alternatives (12).
azo dyes is to increase the size of the alkoxy group ortho
to the azo linkage (18).
4.3.6 Pollution Prevention Measures
As a pollution prevention measure, every dyer should work
only with responsible and knowledgeable suppliers; in-
sist on complete identification of all dyes and chemicals,
as well as full environmental impact information; be
conservative in the handling and use of all dyes and
chemicals; and arrange processes to ensure maximum
utilization and minimum waste from spent processing baths
and handling. Dyers should follow established principles
for the safe handling of dyes.
Dye manufacturers should help dyers consider environ-
mental factors when selecting dyes by providing more
information concerning the ingredients of their products.
A dyer should evaluate dyes from an environmental
point of view according to the following factors:
• Safety of the dye and its metabolites.
• Aquatic toxicity.
o-u
N N
Figure 4-3. Some mutagenic dye Intermediates and nonmu-
tagenic alternatives (12) (continued).
• Metal content.
• Ability to be decolorized, degraded, or treated by
biological degradation, chemical destruction, sorp-
tion, or precipitation.
• Toxicity of degradation products.
• Propensity to produce hazardous wastewater treat-
ment sludges.
• Exhaustion typically achieved in a dyeing process.
The need for better disclosure of dye structures and
properties is obvious. Although dye manufacturers are
increasingly aware of the need to provide more informa-
tion, future trends may not bode well for better disclo-
sure of dye ingredients and environmental impacts,
given the need to protect proprietary business informa-
tion. In the past, many dyes have been classified by
chemical structure and applications factors in the Cl.
The CI is a dual classification system for dyes in which
the dyes are grouped according to chemical class (with
a Cl constitution number when the chemical structure is
known for each chemical compound) and use or appli-
cation class (with a Cl generic name for each dye,
whether made by one or several manufacturers). The Cl
is the standard means of identification for textile dyes.
The Cl generic name is derived from the application
class to which the dye belongs, the shade or hue of the
136
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dye, and a sequential number, all of which gives clues
about the possible environmental effects of the dye.
This indexing system seems to be coming to an end
because many of the major dyestuff companies have
withdrawn their support. In the future, dyes will become
more proprietary, like specialty products, with an asso-
ciated loss of information for the user. In the future, lack
of information will make evaluation of pollution prob-
lems, substitutions, and other aspects of the dye selec-
tion process even more difficult for textile mills because
they will know even less about the chemical constitution
and structure of the dyes that they are using.
Dyers must rely on vendors for environmental informa-
tion on dyes, but, in the final analysis, dyers must care-
fully evaluate environmental and other claims about
dyes using their own site-specific processes, equip-
ment, and experience.
4.4 Chemical Specialties
The following table introduces pollutants and waste
streams discussed in this section, as well as pollution
prevention activities suggested for each.
Pollution Prevention
Pollutant or Actions Described
Waste Stream in This Section Comments
4.4, Chemical Specialties (General)
All pollution types Understanding of the Further details for
resulting for types and roles of specific specialties of
specialty chemical chemical auxiliaries highest importance in
auxiliary use in textile processes, pollution prevention
(e.g., water, air, possible alternatives, are in the sections
hazardous and and the' importance thai: follow (4.4.1
solid wastes) of prescreening and through 4.4.3.2)
raw material QC
4.4.1, Proprietary Nature of Chemical Specialties
All pollution types Better information
resulting for exchange between
specialty chemical chemical supplier and
auxiliary use user (mill), sources of
(e.g., water, air, information,
hazardous and prescreening and
solid wastes) incoming QC
Pollutant or
Waste Stream
4.4.2.1, Warp Size
BOD, COD
Aquatic toxicity
4.4.2.2, Permanent
Formaldehyde
4.4.2.3, Softeners
General pollution
from softener use,
especially aquatic
toxicity and air
emissions
4.4.2.4, Builders
General pollution
from the use of
builders, including
formaldehyde
4.4.2.5, Surfactants
General: all types
of pollutants from
surfactants
BOD, COD
Pollution Prevention
Actions Described
in This Section
Understanding
of alternatives,
. consequences
of selection, •
possibility of
recovery
Understanding
of alternatives,
consequences
of selection
Press Finishes
Formaldehyde-free
alternatives
Understanding
of available types
of softeners,
their respective
performance
characteristics,
and selection
criteria
Understanding
of available types
of softeners,
their respective
performance
characteristics,
and selection
criteria
Better understanding
of the types,
occurrences, and
uses of surfactants,
as well as their
special properties
Surfactant selection
Comments
Removed size is
generally wasted to
the desize operation
(see Section 4.9.2.1)
Explained in Sections
4.7 and 4.9, "Sizing
and Preparation"
Further information is
in Section 4.12,
"Finishing"
See also Section
4.12, "Finishing," for
further information
See also Section
4.12, "Finishing," for
further information
Several types
(cationic, anionic,
noinionic, amphoteric)
are discussed. Their
properties (both
performance and
pollution) are
discussed ana
sources are identified
Tables of BODs are
4.4.2, Types of Chemical Specialties
All pollution types Better understanding
resulting for ....
specialty chemical
auxiliary use
(e.g., water, air,
hazardous and
solid wastes)
Aquatic toxicity
of the types and
uses of processing
assistants
An example is given;
complete description
of all types and uses
of textile specialty
processing assistants
is beyond the scope
of this or any other
single document;
important specialties
are reviewed in the
following sections
Surfactant selection;
better testing
methods
4.4.3, Pollution Prevention
Warp size Reduction of the
need for warp size
through fabric design,
loom selection, and
loom operating speed
BOD from warp Size selection
size
given
Comparison of
various types for raw
waste and treated
waste toxicity are
explained
A global issue; the
gains in wet
processing must be
balanced against the
losses in weaving
A global issue; the
gains in wet
processing must be
balanced against the
losses in weaving
137
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Pollutant or
Waste Stream
Pollution Prevention
Actions Described
In This Section
Comments
Aquatic toxicity
from warp size
BOD from surfac-
tants
Aquatic toxicity
from surfactants
Size ingredients
control; better
understanding of the
performance and
environmental
consequences of size
additives
Surfactant selection
Surfactant selection,
avoiding cationics in
particular; chemical
prescreening
Removed and wasted
at desizing operation
(see Section 4.9.2.1)
Includes case histories
4.4.4, Other Pollution Prevention Measures
All types of pollu-
tion from chemical
specialty use
Cleaning up and
packaging wastes
Use of mechanical,
not chemical,
remedies for process
and/or equipment
inadequacies
Avoiding overuse of
specialty processing
assistants; reduction
of chemical specialty
use
Getting better
information from •
vendors and* using
MSDS information
Chemical
prescreening and
incoming specialty
raw material QC
Understanding
measures of
treatability
Bulk purchases and
returnable IBCs
Case histories are
included
Specific pollutants
are identified in the
description of
processes in which
the specific
specialties are used
Avoid drums and
bags if possible
The textile industry uses several thousand chemical
specialties, each designed to accomplish a specific pur-
pose in processing and finishing operations. The selec-
tion and use of these chemical specialties has a
considerable impact on the amounts and types of pol-
lutants generated at textile facilities. This section re-
views the types of chemical specialties used, discusses
their pollutant impacts, and describes strategies for their
selection and use that can minimize the amount of
pollution generated.
Most textile wet processing operations use chemical
specialties, but the major specialty-consuming opera-
tions are sizing, scouring, bleaching, dyeing, printing,
and finishing. Vendors offer a wide array of chemical
specialties for use in these processes. A recent list
compiled by The American Association of Textile Color-
ists and Chemists (AATCC) contained more than 5,000
proprietary specialty products in 100 categories. An in-
dustry consisting of approximately 175 companies mar-
keted these chemicals (19). The major categories of
chemical specialties used in textile processing include
surfactants; warp sizes; thickeners; and finishing chemi-
cals such as water and soil repellents, durable press
finishes, and flame retardants. A complete list of catego-
ries from the AATCC Buyers Guide (19) is shown in
Table 4-19.
Chemical specialties represent one of four major sources
of pollution in textile wet processing operations. Other
sources include dyes and pigments, chemical commodi-
ties (including incoming water), and incoming sub-
strates. Chemical specialties represent a pollution
prevention challenge, primarily because they are used
in so many operations and because knowledge of their
constitution is limited by their mostly proprietary formu-,
lations. Considering the large quantities of chemical
specialties consumed by the textile industry, relatively
little information is available concerning their pollutant
characteristics.
The use of chemical specialties is so widespread in
textile manufacturing that techniques for preventing pol-
lution from their use are discussed throughout this docu-
ment. Other sections of this manual that deal with
chemical specialties are: Section 2.2.5, "Metals," 3.5,
"Chemical Alternatives," 3.7, "Incoming Raw Material
Quality Control," 3.11, "Optimized Chemical Handling
Practices," 4.7, "Slashing and Sizing," and 4.12, "Finish-
ing," among others. This section provides an overview
of chemical specialties and discusses, in-depth, those
specialties not covered in other sections. The main points
made concerning chemical specialties in this section are:
• Pollution prevention for chemical specialties is impor-
tant but difficult to implement because of proprietary
formulations and the difficulty of obtaining information
about environmental effects.
• The selection and specification of chemical special-
ties is essential to the overall pollution prevention
strategy because of the wide range of environmental
impacts that could result from different proprietary
formulations.
• QC of chemical specialties is important because low-
quality chemicals, or variability in chemical quality,
can result in greater pollution or in batches of low-
quality goods.
4.4.1 Proprietary Nature of Chemical
Specialties
Chemical specialties used in processing generally com-
prise proprietary blends of low-cost commodity chemi-
cals. These blends are sold at specialty prices because of
the vendor's expertise, not only in mixture composition
but also in applying the products to solve site-specific
processing problems. For this reason, the formulations
almost always are considered proprietary. Although by
law the vendor must supply a material safety data sheet
(MSDS), specialty formulators are not required to reveal
138
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Table 4-19. Categories of Proprietary Chemical Specialties in the Textile Industry (19)
Accelerators
Acids, fatty
Acids, inorganic
Acids, organic
Adhesives
Antichlors
Anticreasing agents
Antifoaming agents
Antifume agents
Antimicrobial agents
Antioxidants
Antislip finishing agents
Antistatic agents
Atmospheric fading protective agents
Binders for fabrics, yarns
Binders for pigments
Bleaching agents
Bleaching assistants, stabilizers, and
catalysts
Builders, detergent
Carriers, dye
Catalysts
Chelating agents
Coating agents and assistants
Coning and winding lubricants
Corrosion inhibitors
Crease-resisting finishing agents
Curing assistants
Degreasing agents
Degumming agents and assistants
Deliquescents
Deodorants
Depitching agents
Desizing agents
Detergents and assistants
Discharge printing agents and assistants
Dispersing agents
Dulling agents
Durable press agents
Edge binders
Emulsifying agents and assistants
[Enzymes
Fixing agents for dyes
F:lame retardants
F:oam inhibitors
froaming aids
F:ulling agents and assistants
F-"umigants
F:ungicides
Gas fading inhibitors
Germicides
Gums
Hand builders
Hygroscopic agents, humectants
Insecticides and insect repellents
Iron stains, agents for prevention and
removal
Kier boiling agents and assistants
Levelling chemicals
Loading agents
Lubricants for textiles
Mercerizing assistants
Mildew preventatives
Milling agents
Mordants and metallic salts
Moth resisting agents
Monslip finishes
Nonwoven binders
Odorants, odor-masking agents, and
deodorants
Oil repellents
Oxidizing agents
Paint and tar removers
Penetrating agents
Polymers
Printing assistants and catalysts
Protective agents for wool and silk in wet
processing
Reducing agents
Resins
Resists, dye
Retarding agents
Rewetting agents
Rubbing fastness, agents for improving
Rust preventatives
Scouring agents and assistants
Scrooping agents
Sequestrants
Shrinkage controllers (other than
anticreasing agents)
Silver-fish repellents
Sizing agents
Slip-proofing agents
Soaping agents for prints and dyeing
Soaps
Softeners
Soil release/stain release finishes
Solvents, formulations
Scouring agents
Spinning agents
Spotting agents
Stripping agents and assistants, dyes
Stripping agents and assistants, finishes
Surfactants
Tar removers
Thickeners
Throwing oils
Tints, fugitive
Ultraviolet absorbers/light stabilizers
Water repellents
Water softeners and normalizers
Water treatment agents
Waxes
Weighting agents
Wetting agents
Whitening finishes, fluorescent
Winding lubricants
Wool scouring agents and assistants
specific information to mills about pollutants generated
by the specialty. This greatly complicates mills' efforts to
identify and reduce their use of problem chemicals.
The proprietary nature of specialty formulations is a
complex issue. Although the vendor wishes to keep
formulations secret to protect commercial interests, the
mill may need information about the chemical to prepare
for spills, disposal, treatment, reporting, and compli-
ance. Proprietary formulations are now a major pollution
prevention problem for mills.
One solution is for the mill to insist on the necessary
information during the prescreening process, which will
ensure that the mill understands pollution issues asso-
ciated with a particular chemical before it begins using
it (see Section 3.7, "Incoming Raw Material Control").
Although some vendors may hesitate or refuse to pro-
vide formulation and environmental effects data, others
realize the increasing need to provide safe, effective
chemicals and to be forthcoming with information about
the chemicals in order to make the sale.
For pollution prevention purposes, the two most impor-
tant pieces of information about chemical specialties are
1) the disclosure of pollutant information, including po-
tential incompatibility with other materials, and 2) better,
more accurate aquatic toxicity data (20). The importance
of this information is discussed further below.
139
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4.4.2 Types of Chemical Specialties
The major chemical specialty categories in the textile
industry are shown in Table 4-19. Essentially all areas
of wet processing in a textile mill use some of these
chemical specialties. Surfactants are used in most wet
processing operations. Finishing involves treating natu-
ral and synthetic fibers with chemical specialties to
transform those fibers into yarn for use as is, or for
weaving or knitting the yarn into fabrics.
Typical finishing recipes for cotton and cotton blends use
a combination of the following chemical specialties:
• Cross-linking resin and its required catalyst.
• Softener.
• Wetting or penetrating agent.
• Sewing lubricant.
• Handbuilder (stiffener).
• Functional additives (e.g., water repellent, flame re-
tardant).
Specific chemical specialties used in finishing include:
• Oils, waxes, and fats.
• Starches and polymers.
• Tints.
• Esters (butyl stearate, .trideeyl stearate, oleates,
palmitates, lau rates, trimethylolpropane trispelar-
gonate, pentaerythritol tetrapelargonate, di(2-ethyl-
hexyl) adipate, azelates, and sebacates).
• Polyoxyalkylene glycols and poly(oxyethylene-oxy-
propylene) ethers.
• Silicone and modified silicone fluids.
• Emulsifiers (anionic, nonionic, cationic, and amphoteric).
• Antistatic agents (anionic, nonionic, and cationic).
Data on the sales of textile chemicals indicate the rela-
tive importance of each chemical specialty category. As
shown in Table 4-20, dyes and dyeing auxiliaries make
up the bulk of chemical sales, but other specialties also
are purchased in substantial quantities.
The classes of chemical specialties are too numerous
to describe completely in this manual. The sections that
follow cover the major categories. Specific problems
related to the generation of wastes from chemical spe-
cialties, or to the processes in which chemical special-
ties are used, can be found elsewhere in this manual.
4.4.2.1 Warp Sizes
Size is a chemical mixture applied to warp yarns to
improve the strength and bending behavior of the yarn's
fibers, thereby preventing breakage during weaving op-
Table 4-20. Chemical Sales to the Textile Industry (21)
Sales
Category
Dyes and auxiliary products
Surfactants
Sizes and thickeners
Water and soil repellants
Durable press resins
Flame retardants
Other textile chemicals
Total
Millions of
1987 Dollars
859
177
159
101
94
39
62
1,491
Percent
57.6
11.9
10.7
6.8
6.3
2.6
4.2
100.0
erations. Size is removed from fabrics after weaving has
been completed in a companion process called desiz-
ing, which can generate high pollution loads in textile
effluent.
The three main types of size currently used .are:
• Natural products (starch): Starch, derived mainly from
potatoes and corn, is the most common size and is
used mainly for cotton products and other natural fibers.
• Fully synthetic products: Synthetic sizes include poly-
vinyl alcohol (PVOH or PVA), polyvinyl acetate
(PVAc), polyacrylic acid (PAA), and polyester.
• Semisynthetic products (blends): Semisynthetic sizes
or blends include modified starches, starch ethers,
starch esters, carboxymethyl cellulose (CMC), hy-
droxyethyl cellulose (HEC), and starch-ether and
starch-esters.
In addition to the chemicals listed above, size mixtures
normally include additional auxiliary chemicals that are
added to improve weaving performance, enhance sta-
bility of the size or the sized yarn, and distinguish be-
tween sizes, among other uses.
Starch desizing contributes high BOD loadings to efflu-
ent compared with synthetic desizing. Typical starch
sizes have 5-day BODs of 500,000 ppm to 600,000
ppm, while the BODs of alginates and modified starches
range from 100,000 ppm to 500,000 ppm (11). Synthetic
sizes contribute much lower BOD loadings than
starches, ranging from 10,000 ppm to 30,000 ppm.
These BODs are approximately 15 to 60 times lower
than those for starch. If the synthetic size is recycled,
BOD loadings drop even farther, resulting in an overall
reduction of more than 99 percent compared with starch
(11). Synthetic sizes contribute lower BOD loadings be-
cause they are not biodegradable. Consequently, they
are more likely to pass through wastewater treatment
systems to be discharged to the environment than
starches. At this time, the total size consumption in the
140
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United States is about one-third recoverable. Of the
one-third that is recoverable, only about one-third of that
is actually recovered, or about 10 percent of the total
size used.
Auxiliary components in the size mixture also can affect
BOD levels. Humectants, lubricants (waxes and oils),
antistatic compounds, biocides, glycerine, and wetters
can generate up to 10 or 15 percent of the total BOD
load. Of these auxiliary components, humectants and
lubricants contribute the most to BOD load, typically
accounting for 2 to 5 percent of the total (11).
Auxiliary chemicals added to the size mixture can also
result in toxicity. For example, surfactants and biocides,
which are commonly used, can add to aquatic toxicity.
This issue is discussed further in Sections 4.7, "Slashing
and Sizing," and 4.9, "Preparation."
4.4.2.2 Permanent Press Finishes
Cotton, rayon, and other forms of cellulose and blends
that contain these fibers usually require finishing with a
reactive agent to cross-link adjacent cellulose chains.
This step immobilizes the fibers, reducing shrinkage and
improving bending properties (e.g., crease recovery).
Many types of reactive cross-linkers exist. Currently, the
products of choice for cross-linking cellulose are N-
methylol compounds, which are produced by reacting
urea with formaldehyde and other additives. In applica-
tion and use, N-methylol cross-linkers can release for-
maldehyde.
The most widely used cross-linker for textiles is dimethy-
lol dihydroxy ethylene urea (DMDHEU). This agent usu-
ally reacts with cellulose under high temperatures in the
presence of a Lewis acid catalyst such as magnesium
chloride. When properly used, applied, and cured, formal-
dehyde release from fabrics treated with DMDHEU is
minimal. Afew commercially available nonformaldehyde
cross-linkers eliminate formaldehyde release completely.
These cross-linkers (e.g., DMeDHEU) are considerably
more expensive than DMDHEU and, therefore, have
never been widely used in the U.S. textile industry.
4.4.2.3 Softeners
Finish recipes (which incorporate softeners) often are
made up in the same way that they were many years ago,
without regard for environmental considerations (22,
23). A wide variety of softeners exist, including natural
and synthetic compounds (24). The main types of sof-
teners are fat, petrochemical, and silicon based (25).
The performance of each type of softener varies, and
each has advantages and disadvantages (24, 25). Fatty
acid softeners are biodegradable (24), v/hile both paraf-
fin and polyethylene softeners are nonbiodegradable
(24). Quaternary types have high aquatic toxicity (24).
Mineral oil and paraffin wax softeners are still used
although these types of softeners smoke when heated,
producing air emissions from dryers (22, 23). Polyethyl-
ene glycol (PEG) and polyethylene oxide (PEO), on the
other hand, do not produce volatile organic compounds
(VOCs) during drying and curing. Reactive silicone sof-
teners are very well fixed and do not wash off of the fiber,
whereas most other types wash off during home laun-
dering of the textile products (24).
4.4.2.4 Builders
Functional materials applied to textiles to improve their
softness or feel are known as builders or handbuilders.
These materials include N-methylol film-forming reac-
tive materials (e.g., trimethylol melamine, urea formal-
dehyde), natural polymers (e.g., starches, alginates,
gums), and synthetic polymers (e.g., PVA) (25).
Acrylic handbuilders and stiffeners can replace formal-
dehyde-based N-methylol handbuilders (22, 23). Acryl-
ics are good substitutes in many applications. The use,
however, of acrylate monomers, especially their manu-
facture, is linked to other pollution problems. The algi-
nates, starches, and modified starches are the least
harmful environmentally, but they also have high BOD
and often produce high levels of total suspended solids
(TSS), which are difficult to remove or settle.
4.4.2.5 Surfactants
Surfactants are used in the formulation of almost all
chemical specialties, including:
• Penetrants and wetting agents.
• Solvent and nonsolvent scouring compounds.
• Lubricants and antistats.
• Oil and wax emulsifiers.
« Dispersants for all types of specialties.
• Emulsification systems for many of water-insoluble
processing assistants (e.g., lubricants, dye carriers,
softeners).
A working knowledge of surfactants is important for
production workers and supervisors for several reasons:
• Surfactants are widely used in textile manufacturing
for a variety of purposes.
• The behavior of surfactants often is substantially dif-
ferent than might be expected based on experiences
with other "normal" chemicals.
• Surfactants are one of the main causes of aquatic
toxicity and BOD in textile wastewater.
141
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• Because of the many different types of surfactants
available, selecting the correct surfactant for a particular
function requires a good understanding of perform-
ance and pollution issues.
Fortunately, the wide variety of surfactants available
facilitates the selection of less-polluting alternatives (26).
Unfortunately, this information is often unavailable to the
typical mill production supervisor.
The four basic classifications for textile surfactants are
1) nonionic, 2) anionic, 3) cationic, and 4) amphoteric
(13). Overall, anionic and nonionic surfactants account
for over 90 percent of total consumption, as shown in
Table 4-21 (27).
Based on these data, most pollution prevention efforts
focus on the largest volume surfactant categories, non-
ionic and anionic surfactants. Nonionic surfactants dis-
solve in water without forming ions, while anionic
surfactants dissolve to form negative ions. Cationics,
however, exhibit extremely high aquatic toxicity. Most
textile mills avoid using cationic surfactants because
of their incompatibility with more widely used anionic
surfactants.
The four basic categories of surfactants are described
in more detail in the sections that follow. Examples of
the major product types are provided for each.
Nonionic
Nonionic surfactants have many advantages, including
excellent compatibility in most processing situations,
good wetting and rewetting, good emulsification, and
excellent oil solubility. Nonionic surfactants also are
good components of oil emulsifiers. The disadvantages
of nonionic surfactants include temperature sensitivity
(cloud point), low alkali tolerance, low electrolyte toler-
ance, possible harshening of cellulosic fibers, and
possible dye spotting and/or crocking of disperse dyes
from residual surfactants (28). In addition, surfactants
generally generate large amounts of foam, which may
or may not be desirable in specific situations. Alkylphe-
nol ethoxylate surfactants are one of the largest groups
of nonionic surfactants used, accounting for more than
400 million pounds per year in the United States (29).
Of this, 82 percent (approximately 330 million pounds)
Table 4-21. Consumption of Surfactants in Textiles (27)
Typa Percent of Total
Anionic
Nonionte
Caltonte
Amphoteric
Total
59a
33
7
1
100
* 34 percent synthetic and 25 percent natural soaps.
is ethoxylated nonyl phenol, of which about 80 to 90
million pounds are treated and discharged to rivers each
year (29).
Four examples of common nonionic surfactants are:
• Alcohol ethoxylates: Derived from ethylene (easily de-
graded), propylene, butylene (more difficult to degrade),
or vegetable triglycerides (easy to degrade). They are
known by acronyms such as AE (alcohol ethoxylate)
or LAE (linear alcohol ethoxylate). These surfactants
are used as emulsifiers, wetters, or scouring agents.
• Alkylphenol ethoxylates: Derived from propylene
(most often containing a branched nonyl) or butylene
(containing a branched octyl), and known by acro-
nyms such as APEO (alkylphenol ethoxylates), or
NPE (nonylphenol ethoxylate). Decomposition prod-
ucts of APEOs are phenols, which are toxic to aquatic
organisms such as fish. Used as an emulsifier, wetter,
or scour.
• Tertiary thiol ethoxylate (TTE): Used as an emulsifier,
wetter, or scour.
• Diethanol cocoamide (DEC): Used as a scour, lubri-
cant, and softener, as well as in dyeing.
Anionic
Anionic surfactants commonly consist of sulfates, sul-
famates, sulfonates, sulfosuccinates, phosphate esters,
methyl taurines, carboxy methylates, and metallic and
amine soaps. Four examples of anionic surfactants are:
• Alkylbenzene sulfonates: Linear and branched com-
pounds; only the linear biodegradable compounds
currently are used, and the treated effluent from
processes using these compounds have no known
adverse environmental effects. Used as penetrants,
dispersants, and wetting, scouring, and foaming
agents. Example: dodecyl benzene sulfonic acid
(DDBSA).
• Alcohol ethoxysulfates: Linear and branched com-
pounds; only the linear biodegradable compounds
currently are used. Used as penetrants, dispersants,
and wetting, scouring, and foaming agents. Example:
sulfated ethoxylated alcohol (SEA). These are ethyl-
ene-oxide based, like AE, and demonstrate all of the
desirable properties of nonionics but because they
are anionic, they do not exhibit cloud point and other
problems associated with nonionics. They are some-
times called cryptononionics.
• Naphthalene sulfonic acid (NSA): Used as a disper-
sant for disperse dyes.
• Sodium lauryl sulfate (SLS): Used in scouring, after-
wash.
142
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Anionic surfactants generally are used as rapid wetters,
dispersants, emulsifiers, coemulsifiers, lubricants, and
scouring agents. They also can be used as compatibiliz-
ers, anticoprecipitants, and components in carrier emul-
sion systems (28).
Anionic surfactants have several advantages, including:
• Good oil emulsification
• Good dye dispersibility
• Excellent wetting and rewetting speeds
• Low cost
Disadvantages include:
• Calcium and magnesium sensitivity with sulfate sur-
factants.
• Incompatibility with cationics.
• High foam level.
• Carryover from processing steps that can affect dye
yield in basic or cationic dyeing.
Cationic
Cationic surfactants are relatively uncommon in textile
processing. One exception is fiber finishing, where cat-
ionic surfactants are used as accelerators in weight
reduction of polyester fibers by caustic treatment meth-
ods (28). Cationic surfactants also account for as much
as 12 percent of all fabric softeners used (30). Cationics
lower the surface tension of water and assist in emul-
sion, dispersion, and foam stabilization (31). Two exam-
ples of cationic surfactants are:
• Alkyl dimethyl benzyl ammonium chloride (ADBAC):
An antistatic agent. Also used as a softener and lu-
bricant for cloth.
• Tallow amine ethoxylate (TAE): Used in dyeing and
antistatic treatments, or as a decoupler.
Both of these surfactants exhibit very high aquatic toxicity.
Amphoteric
Amphoteric surfactants are not used widely in today's
textile operations, except in specialized situations that
require wide ranges of compatibility. Amphoterics can be
used in alkaline or acid media and in combination with
either cationic or anionic surfactants. They exhibit excel-
lent lubricant, corrosion inhibition, and wetting action
properties and provide a protective colloid to facilitate
silk and wool processing. Amphoterics are used in
scouring and dyeing of protein fibers to prevent chafing,
crack marks, and crow's feet (28). Nonetheless, am-
photerics are expensive, and some forms are not heat
stable so they cannot be used at elevated temperatures.
Amphoterics have few advantages compared with other
less expensive surfactants. An example of an amphoteric
surfactant is coamphocarboxy propionate (CCP), which
is used for scouring wool and silk.
Surfactant Uses
Surfactants are used in almost every textile process,
beginning with fiber formation. Surfactants are applied
to fiber for lubricity, antistatic properties, or other pur-
poses. Surfactants are also used in processing solutions
for specific purposes such as stabilization of an emul-
sion or dispersion. Surfactants perform a variety of func-
tions in many textile processes, including (11, 26, 29, 31):
• Lubrication processes
• Spin finishing
• Desizing
• Scouring
• .Mercerizing
• Bleaching
• Wet finishing
•, Foam finishing
• Dyeing
• Foam dyeing
• Printing
Surfactants are used in wet processing to ensure com-
plete wetting and penetration of processing solutions
(13). In addition, surfactants can serve as dispersing
agents, emulsifiers, bath detergents, foaming agents,
and levelers. Besides applications in which surfactants
are added directly to a substrate, many textile processes
use water-insoluble processing assistants that are ap-
plied from aqueous emulsions. Essentially all chemical
specialties thus contain surfactants to improve their
solubility and dispersibility and to suspend water-insol-
uble materials in processing baths. This is particularly
important because any precipitation of insoluble mate-
rial is likely to lead to spots or other defects, as well as
equipment fouling.
Surfactant Pollutant Properties
Surfactants may be transferred to the textile wastewater
or remain behind as a residue on fibers, yarns, or fab-
rics. Examples of surfactant-containing residues found
on textile substrates include oils and waxes on natural
fibers," spin finishes on synthetic fibers, winding emul-
sions on yarn, coning oils, yarn finishes, knitting oils, and
warp sizes (13). Further discussion of surfactant resi-
dues may be found in Section 4.2, "Fibers."
In major textile producing countries, textile manufactur-
ing consumes approximately 10 percent of all surfac-
tants. Ultimately, 70 percent of these surfactants are
discharged in wastewater (27). Kravetz reported that
143
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surfactants have been found in raw textile waste at
concentrations of approximately 50 ppm to 200 ppm
(26). Other studies of raw textile wastewater have found
concentrations of specific surfactants at 1,780 parts per
billion (ppb) to 2,400 ppb (29). The concentration of
surfactants in treated effluent depends on the amount of
degradation that occurs during treatment (13, 26).
Surfactant Biodegradability
Surfactants are a major source of aquatic toxicity in
textile wastewater. To reduce toxicity of wastewater,
surfactants must be either eliminated from use or de-
graded via biological treatment. Textile mills concerned
with effluent toxicity should consider pollution prevention
approaches for reducing surfactant use. Surfactant sub-
stitutions in textile processes can have a beneficial effect
on wastewater treatability, as well as residual aquatic tox-
icity after treatment.
The treatability and degradability of surfactants has
been a major topic of study in the textile industry over
the last few years. Kravetz et al. (32), Kravetz (26),
Moore et al. (31), Huber (30), Achwal (27), and Naylor
(29) have all published data related to this, as have the
Chemical Manufacturers Association (CMA) and the
U.S. Environmental Protection Agency (EPA).
Kravetz (32) studied three types of nonionic ethoxylate
surfactants for degradability (i.e., LAE, alkyphenol (AP),
and TTE). In bench-scale tests, LAE was degraded 70
percent and reportedly was harmless to the environment
following treatment. AP passed through the treatment
systems, as did TTE, and were degraded only 25 per-
cent to 30 percent (32). Later work by Kravetz attributed
variable degradability of surfactants to the hydrophobe
part of the molecule, that is, the more linear the mole-
cule, the greater its degradability. Branched hydro-
phobes are less degradable than linear hydrophobes,
and aromatic materials are even less degradable (13).
The failure of some surfactants to degrade completely
can result in problems such as foaming in the receiving
waters and aquatic toxicity. AP was found to degrade
much more slowly at low temperatures (e.g., 8°C) than
at room temperature, whereas LAE was far less depend-
ent on temperature (32).5 In general, laboratory studies
confirm that AP degrades slowly and that intermediate
forms of AP reportedly are more toxic than undegraded
AP in some cases (29).
Recently, an industry group of major surfactant suppliers
studied the fate of AP in the real-world environment
by measuring AP concentration in raw textile waste-
water and in 30 rivers, using special chromatographic
analytical techniques capable of low-level concentration
measurement (ppb). AP from textile operations was
found to degrade between 94 and 97 percent in real-world
waste treatment systems (29). This degradation level
was far greater than that reported in bench-scale tests
previously conducted (26, 31, 32). In wastewaters with
AP concentrations of approximately 2 ppm, the degradation
level in treated effluent was immeasurably low in ap-
proximately 70 percent of the samples. Based on worst-
case scenarios of discharge locations and low-water
flows, almost all in-stream concentrations were below
the no-observable-effect concentration (NOEC) (29).
Despite the differences exhibited in laboratory studies
and real-world treatment systems, no published evi-
dence currently exists to show that AP is more degrad-
able than LAE. The issue of biodegradability is closely
related to the BOD and COD of the materials, as dis-
cussed below.
Surfactant BOD and COD
BOD5 values have been published for a variety of deter-
gents, individual surfactants, and scouring and dyeing
assistants, as shown in Tables 4-22 and 4-23. Incom-
plete surfactant biodegradation within the 5-day time
limit of the standard BOD test results in a large variation
in BOD5 results among different surfactant types. The
COD test with dichromate is more rapid and consistent;
therefore, the COD is higher than the BOD5 and shows
less variability. One measure of biodegradation potential
is the ratio of COD to BOD5. If a surfactant biodegrades
completely in 5 days, the ratio is close to 1:1. As the extent
of biodegradation decreases, the ratio increases (11).
Table 4-22. BODs of Detergents and Surfactants: Product
5-Day BOD (ppm) (11)
5 Sasser, P.E., and B. Smith. Personal communication between P.G.
Sasser, Cotton, Inc., Raleigh, NC, and Brent Smith, Department of
Textile Chemistry, North Carolina State University, Raleigh, NC (July
29).
All detergent
Dreft detergent
Igepal (alkyl phenol EO)
Igepon AP-78 (sodium isothoinate oleate)
Igepon T-77 (sulfonamide)
Isodecyl alcohol 6 EO (Epilsophogene DA 63)
Ivory Snow
Lauryl sulfate
Merpol B (alcohol sulfate)
Neodoi 25-3-S (alcohol EO sulfate)
Neodol 25-7 (12-15 C alcohol/7 EO)
Neodoi 45-7 (14-15 C linear alcohol/7 EO)
Nonyl pehol 10 EO (Igepal CO630)
Orvus K (ammonium lauryl sulfate)
Parval (fatty amide soap)
Rome soap flakes
Sandopan TLF (sulfonated fatty amide)
Santomerse 3 (sodium alkyl aryl sulfonate)
Saponite (solvent scour)
Sulfanol KB (sodium alkyl aryl sulfonate)
Sulfonated castor oil
40,000
49,000
40,000
1,210,000
1,660,000
100,000
1,220,000
1,250,000
440,000
570,000
450,000
650,000
24,000
1,560,000
50,000
1,220,000
50,000
90,000
830,000
0
520,000
144
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Table 4-23. BOD of Dyebath Auxiliary Chemicals: Product
Five-Day BOD (ppm) (11)
Sulfonated vegetable oil
Syndet (amide detergent)
Tallow
Tallow soap
Tergitol 15-S-7 (11-15 C secondary alcohol 7 EO)
Triton 770 (alkyl aryl polyester sulfate)
Triton 771 (polyester sulfate)
Triton X-114 (isooctyl phenol EO)
BP solvent
Duponol C (lauryl sulfate)
Duponol D (alcohol sulfate)
Duponol RA (wetter)
Duraline (solvent scour)
Ethofat C/15 (fatty acid/EO)
Ethofat C/60 (fatty acid/EO)
Ethomid HT/15 (amide/EO)
Ethomid HT/60 (amide/EO)
Extol XP Special
Iberscour
Igepol CA-630 (wetter)
Igepol CA cone.
Iversol (solvent scour)
Kierpine Extra (sulf. oils)
Kreelon 8D (sodium alkyl aryl sulfonate)
Kreelon 8G (sodium alkyl aryl sulfonate)
Kyro AC (fulling)
Merpol B (alcohol sulfate)
Monotone A
Naccosol A
Nacconol NR
Nacconol NRSE
Mnt'nf MC
Neka! NF
Nevtronyx 60D
Orvas Neutral Granules
Parval (fulling)
Dina Oil
rine uii
Pluronic F68 (polyglycol ether)
Rinsol
Sandozol KB (sulf. vegetable oil)
Solpinol Special
Solvent A
Solvent GTS
Solvent T
Solvex
Special Textile Flakes
Strodex
Supertex E
Syndet
Syntholite #100
Triton 770
Triton W30
Ultrawet DS
Ultrawet 35K
Xylol Scour Special
590,000
120,000
1,520,000
550,000
150,000
90,000
50,000
100,000
940,000
1,250,000
450,000
330,000
160,000
1,000,000
220,000
1,000,000
90,000
700,000
530,000
130,000
70,000
600,000
610,000
50,000
230,000
120,000
440,000
200,000
20,000
0 to 40,000
0
120,000
0
30,000
50,000
1 ,080,000
120,000
720,000
150,000
700,000
250,000
410,000
250,000
10,000
1,120,000
120,000
250,000
120,000
100,000
90,000
500,000
0
o
420,000
Anthomine (wool dyeing) 90,000
Carbopen (penetrant) 20,000
Dyes (various) o to 100,000
Dyes (sulfur) Approx. 100,000
Dyes (disperse) Approx. 30,000
Dyes (direct) Approx. 80,000
Dyes (azoic) Approx. 20,000
Azoic couplers (p-naphthol) 100,000
Formopon (hydro/formaldehyde strip) 270,000
Gluconic acid and lactone (vat) 520,000
Glucose corn syrup (vat) 530,000
Lanazin tip (albumin derivative) 90,000
Fluorescent brightener (leucophor) 330,000
Metachloron (fix) o
Peregal OK 20,000
Rexan O (EO leveler) 20,000
Sodium acetate (buffer) 320,000
Sulfoxite (strip) 270,000
Nonbiodegradable surfactants such as high COD-to-
BOD5 ratio detergents are a problem because they are
likely to pass through treatment systems. The best
choices for biodegradable surfactants are those with
ratios in the 2:1 to 6:1 range (33). Some researchers
advocate a top limit of 5:1. Ratios above 5:1 represent
surfactants that are difficult to degrade and should be
avoided. This approximation applies not only to surfac-
tants but also to textile specialties and waste streams in
general (11). The Organization for Economic Coopera-
tion and Development (OECD) test 301 D, "Ready Bio-
degradability,; may also be used to calculate BOD:COD
ratios. International standards state that a BOD28:COD
ratio greater than 60 percent (based on nonaqueous
activities) is readily biodegradable.
Aquatic Toxicity of Surfactants
The Clean Water Act requires acute and chronic toxicity
tests to be performed on waste treatment plant effluent.
Surfactants can contribute greatly to aquatic toxicity.
Some nonionic surfactants are known to kill fish in the
ppm range and produce chronic effects in the 0.1 ppm
to 1 .0 ppm range.
f
To a large extent, the choice of surfactants can control
the toxicity of raw textile wastewater (31). Surfactants
vary in aquatic toxicity as well as treatability, depending
on specific features of their molecular structure. Knowl-
edge of molecular structures, therefore, enables the
processor or chemical specialty manufacturer to select
surfactants with lower aquatic toxicity that are more ame-
nable to degradation in treatment systems. Because elimi-
nating all surfactants from textile processing is impossible,
145
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those that are less toxic and more treatable should be
selected (33). Another important point to realize is that
surfactants are often used as emulsifiers or dispersants
in specialty products that contain significant nonaqueous
components. These nonaqueous components contrib-
ute to aquatic toxicity and therefore deserve attention as
well (see Section 4.4, "Chemical Specialties").
In one bench-scale study, AP was degraded approxi-
mately 25 percent, while under similar conditions, LAE
was degraded 100 percent. Although LAE has higher
aquatic toxicity (LCgo = 2 ppm) than AP (LC50 = 13 ppm)
before treatment, treated effluents showed substantial
toxicity for AP but no toxicity for LAE. Because LAE is
more degradable and has higher BOD than AP, more rapid
oxygen uptake and more waste sludge production would
occur per unit time, but pass-through potential would be
less. Table 4-24 summarizes surfactant toxicity data
from a number of studies. Moore et al. (31) reported that
aquatic toxicity is related to the hydrophilic lipophilic
balance (HLB) of the surfactant. He also determined that
water hardness contributes to aquatic toxicity in surfac-
tant solutions.
In addition to the data presented in Table 4-24, the
aquatic toxicity of cationic materials in general (48- to
96-hour LCso for various aquatic species) is high, between
0.6 ppm and 2.6 ppm, with the NOEC ranging from 0.05
ppm to 0.5 ppm (30).
4.4.3 Pollution Prevention
Because chemical specialties are so ubiquitous and
often cause high aquatic toxicities, high BOD levels, and
other pollution problems, all facets of chemical specialty
use must be examined. Particular operations that re-
quire attention include chemical handling and storing,
chemical auditing, automated dispensing, chemical sub-
stitution, container reuse, dyebath reuse and other proc-
essing changes, and optimal process chemical choice,
among others. Many of these options are discussed in
other sections of this manual. The following sections
discuss particular process areas and specific chemicals.
4.4.3.1 Sizing
Significant reductions in pollution can be achieved by
carefully selecting the type of warp size, optimizing
sizing operations, and instituting size recycling. Proper
fabric design, loom selection, and operating speeds, as
well as careful control of the size mixture and add-on
level present the need for excessive amounts of size. In
this case, pollution prevention activities must take place
within one unit operation while another unit operation
enjoys the benefits (see Section 4.17, "Globalization of
Pollution Prevention," for more information).
Selection of the most appropriate size for a given opera-
tion is complicated, partly because of the many different
Table 4-24. Aquatic Toxicity of Surfactants
Class Type LC50 (ppm)
Reference
Nonionic
Anionic
Cationic
Amphoteric
TIE
DEC
LAE
AP
DDBSA
NSA
SLS
SEA
ADBAC
TAE-15mol EO
TAE-15mol EO
CCP
17.32
28.4
2.4
5.4
0.8
0.5 to 150
12.5
2.9, 1.6
1.3 to 1,000+
19.9
Not reported
27.8
20.2
0.4 to 400
11.9
4.1
66.1
159.1
31
32
31
31
32
34
31
32
34
31
31
31
34
31
31
31
31
sizing materials that are available to the textile manufac-
turer. Different fiber types, weaving looms, cost require-
ments, pollution characteristics, and other factors need
to be balanced when selecting a size.
Choosing synthetic sizes can result in large reductions
in pollution. Synthetic sizes have inherently lower BOD
levels than natural sizes, and can be recycled and
reused. By moving from a high-BOD starch to a low-
BOD synthetic that can be reused, BOD output can be
reduced by nearly 100 percent. Several warp size alter-
natives to starch are available, such as PVA, CMC,
PVAc, PAA, and polyester. These materials differ con-
siderably in their BOD and COD content, as well as the
degree to which they are degraded during desizing. PVA
and CMC are low-BOD, recoverable sizes that should
be considered as alternatives to starch.
During size selection, the nature of additives in the size
mixture also should be considered. Surfactants and
biocides in starch mixtures contribute to BOD, and their
use should be examined in light of the facility's overall
pollution prevention goals. Additives can also interfere
with the recyclability of sizes (see Section 4.7, "Slashing
and Sizing").
4.4.3.2 Surfactants
Until recently, AP was the preferred nonionic surfactant
for several reasons (27). The wetting and emulsification
performance of AP in textile processes is excellent, and
146
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the cost Is competitive. Also, many municipalities com-
pute sewer charges using a formula based in part on the
BOD content of wastewater, providing an incentive for
industries to seek out the lowest BOD surfactants. AP-
type surfactants generally have BODs in the range of
20,000 ppm to 200,000 ppm (11).
In light of studies showing aquatic toxicity in treatment
residues from AP, however, attitudes regarding surfac-
tant selection have changed (27). The German Associa-
tion of Textile Auxiliary, Tanning Agent, and Detergent
Manufacturers voluntarily ceased production of AP-
containing products on January 1, 1992, and now
suggests that LAE be substituted in formulations (7).
Most experts agree that selecting the most degrad-
able surfactants is necessary to solve aquatic toxicity
problems (32). At this time, the best known pollution
prevention practice is to replace AP with LAE. Research
into better substitutes continues (7).
As discussed in Section 4.4.2.5, a practical guide for
evaluating chemical specialties is the ratio of COD to
BOD, which indicates the ability of the chemicals to
biodegrade. Criteria such as OECD 301D for evaluating
ready biodegradability of products or waste streams
have been discussed previously in Section 4.4.2.5. An-
other important procedure is to avoid the use of ex-
tremely toxic cationic surfactants, which often are found
in lubricants and fabric softeners (30). If no substitute is
available, then handling, storage, and use of cationic
surfactants should be carefully controlled and proper
training, auditing, application procedures, and work
practices should be established.
Case History: Surfactants
The City of Mount Airy in Surry County, North Carolina,
operates a trickling filter treatment system for 14 textile
mills and a population of 7,600. Effluent from this
system was found to be high in aquatic toxicity, contain-
ing potentially toxic levels of copper, zinc, and surfac-
tants, especially APs.
The City of Mount Airy requested that each textile mill
review its use of APs, and substitute, eliminate, or opti-
mize/reduce the use of these surfactants. Within 60
days, the toxicity of effluent from the treatment system
decreased substantially. This decrease was attributed
primarily to the substitution of LAE for AP. Before in-
dustrial source reduction efforts, toxicity (48 hours LC50
static daphnid bioassay) was 51 percent. Following
changes in the types of surfactants used at the mills,
toxicity was reduced to a level of greater than 90 per-
cent. Effluent from the treatment system then regularly
passed North Carolina Department of Environmental
Management Ceriodaphnia pass/ fail minichronic bioas-
say tests (13).
Similar analyses were performed in the towns of
Reidsville and Concord, North Carolina, with similar
results (see, for example, Diehl and Moore [35]).
4.4.4 Other Pollution Prevention Measures
In many cases, chemical specialties are used to com-
pensate for inadequacies in equipment or substrate de-
sign. For example, dyebath lubricants are used to
prevent abrasion, creasing, and cracking during dyeing
when the cloth is incompatible with the dyeing machine's
fabric transport system. Often, a change in the running
speed or the temperature of a process can eliminate
such problems without the need for chemicals. As a
general rule, mechanical alternatives should always be
evaluated before adding chemicals to a dyebath.
Chemical specialties also are often used to correct prob-
lems or deficiencies caused by other materials. For
example, defoamers are used to suppress foam that
results from the addition of inappropriate wetting agents.
In addition, bath stabilizers often are added to prevent
bath precipitation when incompatible chemical special-
ties are mixed together. A better strategy in each case
is to remove the chemical that is causing the problem or
replace it with a better product, rather than simply add-
ing more chemicals to the bath.
Moore (36) reported a typical example of this issue in a
hosiery mill. The facility processed nylon pantyhose and
was out of compliance with a publicly owned treatment
works (POTW) pretreatment ordinance for BOD, COD,
and zinc. Vendor information .and MSDSs were re-
viewed, and conditions that necessitated chemical spe-
cialty use were identified and corrected. The mill
reduced its use of chemical specialties by 70 percent in
the acid dyeing process and by 33 percent in the dis-
perse dyeing process. Overall, the mill reduced chemi-
cal specialty use from 11 percent to 5 percent on weight
of goods (owg). The end result was a 40-percent reduc-
tion in BOD and COD and elimination of the zinc
problem (36).
4.4.4.1 Obtaining Information
Users of chemical specialties must request and review
all information about chemical specialties before using
them at the mill. At this juncture, the supplier has an
incentive to supply the information required to complete
the sale. Further, unless users request pollutant infor-
mation, suppliers might not realize that customers value
the availability of low-polluting products that perform
well in their operations.
To facilitate access to information about chemical spe-
cialties, databases currently are being set up to provide
users with information about chemical composition,
while maintaining vendor confidentiality. A consortium of
textile companies, chemical suppliers, and fiber suppliers,
147
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along with the North Carolina Department of Environ-
mental Management, is sponsoring the development of
one such database at North Carolina State University.
The potential for reducing pollution through the use of
certain chemical specialties will be evaluated based on
information about the chemical commodities constitu-
ents of these specialties. The database is under devel-
opment, and data collection from.the standard literature
Is underway (37).
4.4.4.2 Selecting/Prescreening Chemicals
Textile mills traditionally have used performance, cost,
and vendor support as the main criteria for evaluating
new chemical specialties. Now, however, the textile in-
dustry is increasingly interested in reducing its use of
chemical specialties and finding less-polluting alterna-
tive chemicals or cleaner technologies. The incentive
for seeking less-polluting chemicals and technologies
varies and can include regulatory compliance, worker
protection, community or shareholder relations, or par-
ticipation in voluntary chemical use reduction programs.
Users of chemical specialties often find that vendors are
reluctant to reveal pollutant information about such
products. This reluctance is not necessarily because the
vendors believe the information might reflect negatively
on their product. Although environmental testing is re-
quired for most new chemicals or new applications of
existing chemicals, many manufacturers do not have
systems in place to supply this information to vendors
at the sales and marketing level, where customers are
most likely to request the information. Vendors are real-
izing, however, that environmental awareness at the
sales and marketing level and the availability of environ-
mentally friendly products are market advantages today.
Textile mills that have existing chemical specialty pre-
screening programs should review their programs to
ensure that they fully consider environmental effects of
the chemicals. If no prescreening program is in place,
the checklist below, which describes a prescreening
protocol that several companies use successfully, can
be used (11):
• Cost and performance.
• Hazardous waste characteristic (ignitability, toxicity,
corrosivity, reactivity, flammability).
• Priority pollutant status (the list of 126 chemicals)
(see Table 2-25).
• Listed 33/50 chemicals.
• Availability of safer alternatives.
• Biodegradability.
• Heavy-metal content.
• Percentage solids.
• Potential for accumulation in the facility.
• Potential for release to the environment.
• Indoor air pollution potential.
• Hazard potential when mixed with other chemicals.
• Hazardous and toxic air pollutants.
• Proposed manner of use.
• Ultimate fate of the chemical.
• Hazard potential to the customer.
• Who will handle the chemical.
• How the chemical will be used (other chemicals to
be mixed with, concentrations).
• Whether the user requires special safety equipment.
• Spill procedures, incompatibilities, etc.
• Type of packaging (returnable, bulk).
Various authors have suggested several specific pre-
screening criteria and, although mills should not rely on
these criteria alone to satisfy their environmental goals,
the criteria might be helpful in cases where more de-
tailed information is not readily available. One recom-
mended criterion, for example, is to select chemicals
that are at least 90 percent biodegradable in activated
sludge treatment systems (38). A second method is to
compare the COD to BOD ratio (11). This number
should be between 2:1 and 5:1 for typical chemical
specialties. Higher numbers indicate that the materials
are more likely to resist biodegradation and pass
through waste treatment systems. Three OECD meth-
ods are also useful in these evaluations: 301D for bio-
degradability, 209 for biomass impact, and 202 for
daphnia toxicity. Databases (e.g., Aquatox) for these
data are being introduced for commercial use.
Chemical specialties also should be screened for the
presence of any 33/50 chemicals. Under its 33/50 Pro-
gram, EPA has asked industry to voluntarily reduce its
use of 17 chemicals on the Toxics Release Inventory
(TRI) by 33 percent by 1992 and 50 percent by 1995.
The 33/50 chemicals found in textile operations include
1,1,1-TCE (spot remover), perchloroethylene (dry clean-
ing), and methyl ethyl ketone (MEK)/methyl isobutyl ke-
tone (MIK)/toluene/xylene (latex coating operations) (39).
A prescreening evaluation for new chemicals can be
done effectively by a committee that includes the follow-
ing (11):
• Nurse or hygienist.
• Chemist.
• Production department manager (where the chemical
will be used).
148
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• Safety officer.
• Waste treatment system operator.
• Others as appropriate.
Involving the vendor in the prescreening process is also
important because the vendor has information about the
product that the mill does not. The vendor, however,
does not control the use conditions of the chemical or
handling practices. The mill must discuss the intended
application of the chemical with the vendor so that the
vendor can anticipate any potential problems. For more
information on this as a global approach, see Section
4.17, "Globalization of Pollution Prevention."
4.4.4.3 Maintaining Incoming Chemical Quality
Control
The quality of chemical specialties can vary from batch
to batch, and variations in quality can have a significant
effect on process conditions, environmental releases,
and final product quality (1). The customer should work
with vendors to set acceptable guidelines for the purity
and content of chemical specialties before purchase (1).
After deciding to adopt a chemical, the mill must estab-
lish a regular program of quality control verification to
ensure that chemical quality requirements are being met.
Each shipment should be checked when it is received.
Once prescreened and approved for use, samples of
incoming chemicals should be tested 1:o ensure consis-
tency (11). Because chemical specialties are generally
of unknown composition, the suggested tests are not
chemical-specific. Developing specific tests for each
chemical specialty mixture is not realistic in a commer-
cial textile setting. The following checklist describes an
incoming chemical QC protocol (11):
• Permanently mark the date that the drum/container
was opened as a visual verification that the test was
done and as an aid in detecting aged chemicals.
• Check pH with pH meter or pH paper and record (for
aqueous products).
• Check viscosity with Zahn cup and record.
• Check density with hydrometer and record.
• Determine percentage solids by evaporation in an
oven and record.
• Note color and clarity visually and record.
• Note odor and record.
• Check conductivity with handheld conductivity meter
and record (for aqueous liquids).
•. Check index of refraction with handheld refractometer
(for clear liquids) and record.
• Compare data with previous history and vendor's
standard values.
• Enter the data on a control chart for display.
• Keep carefully documented records for each chemi-
cal on a long-term basis.
• Retest drums that have been open for a long period.
• Review all data with the vendor.
All incoming QC data should be reviewed with the ven-
dor, even if no problem is indicated. Reviewing data
accomplishes two important functions:
• Builds rapport and acceptance of test data, which will
be valuable if a problem arises.
• Alerts the vendor that the customer is testing incom-
ing materials and establishes acceptance criteria for
those materials.
4.4.4.4 Selecting Packaging
One crucial area to cover with the vendor during pre-
screening is to ensure that packages will be returnable
without being cleaned on site. Offsite cleaning transfers
chemical wastes back to the production facility, which
presumably is better able to handle wastes than the
textile mill. Chemical specialties should be purchased in
returnable, reusable containers, preferably IBCs (40).
Returnable IBCs or bulk purchases eliminate waste
packing materials and may provide other benefits,
such as:
• Reduced spillage
• Reduced handling costs
• Reduced packaging waste
• Reduced worker exposure to chemicals
• Simplified inventory
• Reduced cost of chemicals that are bought in bulk
• Savings in storage space (IBCs are stackable)
If IBCs are not available or purchasing them is not
practical and drums or bags must be used, the mill
should follow the recommendations below.
When purchasing chemicals in drums, returnable con-
tainers should be specified, and the vendor should be
required to accept unwashed drums for return. Eliminat-
ing the need to wash each drum before pickup prevents
a significant amount of wastewater pollution at the textile
facility.
Many chemicals are purchased in bags (e.g., salt, TSP,
TSPP, soda ash, warp size). Bags are a constant source
of breakage and spillage, and disposing of them is
nuisance. They cannot be stored near high traffic areas
or wet locations. They also must be moved around on
149
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skids, which tend to break, and handling bags requires
a significant amount of labor. Whenever possible, mills
should specify a preference for IBC packaging rather
than bags (all chemicals listed above are available in
IBCs as well as bags).
4.5 Chemical Commodities
The following table introduces pollutants and waste
streams discussed in this section, as well as pollution
prevention activities suggested for each.
Pollutant or Waste
Stream
Pollution Prevention
Actions Described
In This Section
Comments
4.5, Chemical Commodities
Salt
Water (hydraulic load)
Acids and alkalis
Understanding the
role of salt in cotton
dyeing and low-salt
process alternatives
Understanding the
role of water in
various processes
and how to select
and design
equipment and
process, alternatives
for low water use
Understanding the
role of pH and
alkalinity in various
processes, and
alternatives
General reduction of
high-volume pollution
from commodities
Low-level offensive
wastes originating
from commodities
Understanding the
role of commodities
in various processes,
and alternatives
Handling of
commodity
chemicals, especially
the use of bulk
systems
Incoming raw
material QC for low-
level impurities in
high-volume raw
materials
Further information
is in various
sections on the
processes
themselves
Special
maintenance
procedures are
required for safely
operating bulk
chemical systems,
and these are
identified; case
histories are given
Metals in fibers,
toxic agricultural
residues, etc., are
examples
Many types of commodity chemicals are used in textile
manufacturing. Most notable are acids, alkalis, electro-
lytes, oxidizers, organic solvents, and reducing agents.
Other high-volume raw materials include raw water and
fiber. Some of these high-volume inputs are discussed in
the following sections: Sections 2.2.2, "Discharge of Elec-
trolytes," 2.2.7, "Water Conservation," and 4.2, "Fibers."
Commodities are used in extremely large quantities in
textile processing; in some cases, the weight of com-
modities may be as high as the weight of the goods
being processed. For example, the raw materials re-
quired by a 100,000-pound-per-day mill producing fiber
reactive dyed and finished cotton-woven fabric could
include the following top six commodity materials:
Raw Material
Water
Cotton fiber
Salt
Acid and alkali
Peroxide
Silicate
Quantity (pounds)
10,000,000
100,000
80,000
15,000
2,000
3,000
In addition to potential environmental problems associ-
ated with commodity chemicals themselves, the mill
must be concerned with contaminants that may be pre-
sent in commodities. Because of their volumes, the
presence of impurities at the ppm level in commodities
can be a significant problem. For example, an average
zinc level of 1 ppm in the commodities listed above
would contribute 1 pound of zinc to the effluent every 10
days. Because of the potential for this kind of pollution,
commodities must be screened for low-level impurities
and must be purchased from "pure" sources. Low-level
impurities in commodity chemical inputs have not been
comprehensively evaluated. Some data are available for
fibers, however (see Sections 4.2.1 and 4.2.2).
4.5.7 Commodities Versus Specialties
Unlike specialties, commodities are chemicals of known
composition and are sold based on market supply and
demand conditions. Because their chemical composi-
tion is known, incoming QC tests can be directed toward
the actual chemical nature of the commodity, as op-
posed to the generic screening protocols recommended
in Section 4.4, "Chemical Specialties." To prevent pollu-
tion, tests should focus on impurities in the commodity.
These impurities are the result of source contamination
or limitations of the manufacturing processes used to
produce the commodity and serve no useful purpose in
the textile process.
4.5.2 Types of Commodities
Table 4-25 presents some of the most common com-
modities used in textile operations, including:
• Acids (mineral)
• Acids (organic)
• Alkalis
• Buffering salts
• Electrolytes
• Oxidizers
• Reducing agents
150
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Table 4-25. Examples of Commodity Chemicals Used in Textiles
Examples
Commodity
Category
Uses
Acids (mineral)
Acids (organic)
Alkalis
Buffering salts
Electrolytes
Oxidizers
Reducing
agents
Hydrochloric acid
Sulfuric acid
Phosphoric acid
Boric acid
Formic acid
Acetic acid
Oxalic acid
Citric acid
Caustic
Soda ash
Trisodium phosphate
Sodium bicarbonate
Ammonia
Sodium meta silicate
Potassium ortho silicate
Sodium pyrophosphate
Borax
Disodium phosphate
Monosodium phosphate
Sodium 'chloride (common salt)
Sodium sulfate (Glauber salt)
Magnesium sulfate (Epsom salt)
Salt brine (25% sodium chloride solution)
Peroxide
Sodium chlorite
Sodium hypochlorite
Percarbonate
Perborate
Periodate
Permanganate (obsolete—rare)
Dichromate (obsolete—rare)
Sodium hydrosulfite
Bisulfite
Thiosulfate
Thiourea dioxide
Neutralization
Stripping of resin finish
Repair work/stripping dyes
pH control in many processes
Catalyst in resin curing
pH control in many processes
Activator for peroxide bleach
Activator for fiber reactive dyes
Neutralization
Mercerization
pH control (nonvolatile)
Promote exhaustion of cellulosic dyes
Bleach .»
Stripping agent for dyes (repair)
Stripping agent for dyes (repair)
Afterclearing disperse dyes
4.5.3 Quality Control for Incoming
Commodities
A good pollution prevention program includes commod-
ity chemical prescreening and testing of incoming raw
material shipments. Usually, the mill can easily check
the strength or activity of incoming commodity chemi-
cals (41). Tests for that purpose, however, do not reveal
the presence of offensive impurities or contaminants,
such as heavy metals. Most textile mills do not have the
equipment to perform quantitative tests for low-level
impurities in high-volume commodity raw materials.
In many cases, however, the material can be dissolved
in distilled water (for salts), neutralized (for acids and
alkalis), or reacted (for oxidizers or reducers), and the
resulting solutions can be tested for metals using sensi-
tive qualitative-analysis spot tests. Spot test methods
are summarized in the literature (41) and are presented
in detail in Section 3.7. In addition, many contract labo-
ratories run metals analyses using atomic absorption
(AA) or inductively coupled plasma (ICP) techniques for
reasonable prices.
4.5.4 Bulk Systems/Automated Dispensing
Many textile operations use bulk storage tanks and
automatic dispensing systems for commodity chemicals
because of the high volumes used and the price advan-
tage of buying in bulk. The use of bulk systems helps
prevent pollution by reducing small-scale spills, handling
151
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losses, implement cleanup wastes, container washing,
and fluid disposal.
Switching from manual to automated bulk systems in-
volves a tradeoff, however. With manual dispensing sys-
tems, the maximum spill that could reasonably be
expected to occur is usually 55 gallons (one drum) or
less. With automated systems, the potential for a spill of
thousands of gallons is present, although the likelihood
of a spill is lower.
The pollution prevention strategy for manual systems is
to improve packaging, train workers, and emphasize
housekeeping. Switching to bulk handling systems re-
quires that mills provide training for workers and develop
and enforce spill prevention and spill response proce-
dures, to minimize the risk of spills. Further considera-
tions include:
• Sound engineering design of bulk systems, including
segregation of tanks by chemical type; selection of
proper line and tank metallurgy; pumps and check
valves; tank containment systems providing good
secondary (berm) containment; automatic timeout/
shutoff on demand pumps; lockout/tagout provisions;
and alarms.
* Careful installation.
• Clear labeling and identification of tanks.
• Strong preventive maintenance programs for system
components and equipment such as pumps, pipes,
sight glasses, supports, and valves. Frequent and
thorough safety audits.
• Spill control planning.
• Worker training.
• Proper notification of community emergency response
units.
• Proper control and policies regarding deliveries in-
cluding no off-loading except during normal working
hours; two people present during off-loading; safety
shower and eyewash at the off-loading point; and no
bulk delivery truck washing allowed on site.
Sales of commodity chemicals are very competitive, so
to get business, commodity vendors often provide a bulk
tank (as well as design specifications for installation)
either for free or for a modest charge. This service is a
good pollution prevention opportunity for the mill be-
cause commodity vendors have high levels of expertise
In bulk handling of their products. Vendors often have
hotlines or helplines, and some even offer onsite envi-
ronmental and safety inspections of installations.
Below are examples of problems that have occurred at
mills that lack a pollution prevention strategy for com-
modities:
• A 1,000-gallon peroxide tank ruptured and spilled its
contents because an installer did not put the specified
check valve in the delivery line. Process material
backed up into the tank resulting in rapid decompo-
sition of the peroxide.
• A driver went to sleep in the cab of his oil delivery truck
and the tank overflowed. Because no overfill alarm
was present, and only one person was on site during
off-loading, the problem was not detected until too late.
• A delivery hose came loose from its coupling, spray-
ing the driver with chemicals. No plant employee was
present during off-loading. The driver had to go and
search for a shower. By the time he returned, 700
gallons of material had sprayed onto the ground, re-
sulting in a very expensive cleanup. The spill oc-
curred because only one person was present during
off-loading, a safety shower was not present at the
delivery point, and the hose coupling was not prop-
erly maintained.
• A driver pumped catalyst into a reactant tank and
ruined 4,000 gallons of resin because the tank was
not properly labeled. Although expensive chemicals
were ruined, the consequences could have been
much worse.
4.6 Yarn Formation
The following table introduces pollutants and waste
streams discussed in this section, as well as pollution
prevention activities suggested for each.
Pollutant or Waste
Stream
Pollution Prevention
Actions Described
In This Section
Comments
4.6, Yarn Formation (General)
General for all types
of pollution resulting
from yam formation
Reworkable fiber
waste
Nonreworkable waste
(e.g., packaging
waste, trash, hard
waste)
Understand
processes, process
flows, and
alternatives, as well
as fiber alternatives
Recycle within
process
Select reusable
packaging types,
then recycle
Identify causes of
waste and educate
employees, maintain
equipment, etc., to
eliminate or minimize
these causes
4.6.1, Yarn Formation Process
Process waste Segregate, recover,
reuse, develop
markets, and sell
Waste control in
spinning is very
advanced because
spinning is a major
cost factor
152
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Pollutant or Waste
Stream
Pollution Prevention
Actions Described
in This Section
Comments
Controllable-cause
waste
Packing materials and
other solid waste
(e.g., bale wrap,
cones, tubes, straps)
Chemical additives
Identify causes of
waste (worker error,
off-specification raw
materials, equipment
malfunction,
housekeeping,
improper procedure),
then take remedial
action
Involye suppliers as
discussed in Section
1.3.3 ;
Having global
perspectives
These are
removed in wet
processing (see
Sections 4.9 and
4.17 for more
information)
4.6.2, Types of Waste Associated With Spinning
Trash (nonlint)
Sweeps, fly, and invis-
ible waste
Use improved raw
materials (from
agriculture)
Use better cotton
varieties and better
ginning procedures
Identify causes of
waste (worker error,
off-specification raw
materials, equipment
malfunction,
housekeeping,
improper procedure),
then take remedial
action
Section 4.2, "Fibers," as are the pollution prevention
opportunities associated with synthetic fiber formation.
4.6.1 Yarn Formation Processes
4.6.1.1 Continuous Filament Yarns
Filament yarns are continuous forms in which the length
of the fiber is essentially infinite, resulting in the yarn's
structural strength and integrity. A single continuous fila-
ment yarn may typically have as few as one (monofila-
ment) or as many as several hundred filaments. Table
4-26 contains examples of fibers that are typically used
in filament form, including a wide variety of manmade
polymers, some regenerated natural fibers, as well as
silk and a few other natural fibers.
Manmade filament is formed by liquefying the polymer,
extruding it through an opening of appropriate size and
shape, and resolidifying it into a solid continuous fila-
ment yarn. The liquid state may be either a melt or a
solution. Fibers that are melted and extruded resolidify
through cooling. Alternatively, the polymer may be dis-
solved to bring it to a liquid state for extrusion, then
resolidified by either immersing it in a coagulating bath
(wet spinning) or evaporating the solvent (dry spinning).
In either case, residual solvents or components of the
coagulation bath can be present in the continuous fila-
ment yarn. After the spinning process, the yarn then
undergoes one or more postextrusion processes, such
as annealing, drawing, crimping, texturizing, finishing,
and winding. This is depicted in Figure 4-4.
Train workers
Improve waste
collection and
handling
Reworkable waste Improve waste
collection and
handling using
vacuum capture at
the source
Hard waste Identify causes of
waste and educate
employees, maintain
equipment, etc., to
eliminate or minimize
these causes
Packaging Use reusable cones, Requires supplier
yarn cases, pallets, coordination and
and bale wrap global views
Use clear plastic
shrink wrap, not
opaque cardboard
yarn cases
This section describes pollution prevention opportunities
in yarn formation operations. The discussion is limited
to pollutants and contaminants formed or released dur-
ing spinning. Methods to address pollution associated
with raw fiber contamination are discussed separately in
Spun synthetic fibers can include residues from numer-.
ous sources, including:
• Polymerization (e.g., monomer, trimer, oligomer,'
catalyst).
• Melt additives (e.g., delusterants, colorants).
« Extrusion auxiliaries (e.g., surfactants).
• Natural fiber regeneration (e.g., solvents).
• Fiber derivitization (e.g., xanthates).
• Fiber finishing (e.g., antistatic agents, weighter).
Table 4-26. Fibers Typically Used in Filament Form
Synthetic Regenerated Natural
Acetate Rayon Silk
Triacetate Chitosan/Chitin
Acrylic Rubber
Aramid -
Modacrylic
Polyamide (nylon) %s
Polyethylene
Polypropylene
Polyester- :-
Saran •
Spandex
153
-------
Melt Extrusion
Wet Extrusion
Dry Extrusion
Polymerization Reaction
Dried Polymer Flakes or Chips
Liquid Polymer
Threadline
PolymefsolutiorKThreadline
Wash and Dry]
t Polymer Yarn
Postprocessing:
Anneal
Draw
Wash
Texturize
Finish
Wind
Continuous Filament yarn to go
to the fabric forming operation
or for cutting into staple.
Figure 4-4. Production sequence for synthetic continuous filament yarn production.
• Tints (e.g., for identification).
• Winding (e.g., mineral oil, wax).
• Other postextrusion processing (e.g., lubricants,
humectants).
All of the postextrusion processes listed above are part
of the fiber manufacturing process, covered in Section
4.2, "Fibers."
Filament yam can be cut into staple of any desired
length and can be spun on various spinning systems
detailed below.
4.6.1.2 Spun Yarns
The spinning process takes natural fibers with a finite
length and combines them to produce a yarn with supe-
rior strength and structural integrity properties. Synthetic
or regenerated filament fibers are often cut into shorter
lengths so they can be blended with natural fibers and
spun into yarn, or to improve their tactile properties in
an effort to emulate natural yarns. For example, filament
polyester is often cut to 1.5-inch length for blending with
cotton staple in polyester/cotton blended spun yarns.
Acrylic is often cut into longer length to emulate the
154
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tactile properties of wool. These finite-length forms of
fiber are called staple. The typical length of wool fibers
ranges from 2 inches to 12 inches (special varieties up
to 18 inches), and cotton fibers range from 0.8 inches to
1.4 inches.
Spinning provides spun yarns with structural integrity
and strength. This is achieved by aligning the individual
fibers in a parallel direction and inserting a precisely
controlled amount of twist into the yarns to cause indi-
vidual fibers to bind together through interfibrous fric-
tional forces. The methods of controlling staple fiber
orientation, alignment, cleaning, evenness, and twist are
highly length dependent; thus, staple fibers of widely
differing lengths are not compatible for spinning to-
gether. In cotton/wool blends, for example, the wool
must be cut to a length similar to the cotton staple length
to facilitate processing. Thus, two spinning systems are
used: long staple spinning (woolen and worsted system)
and short staple spinning (cotton system). Short staple
spinning is by far the most prevalent type. The two
systems differ greatly in several details. Figures 4-5 and
4-6 show the typical steps in each production sequence,
and the paragraphs below highlight the differences.
4.6.1.3 Long Staple Spinning
Long staple yarn production includes wet processing
steps interspersed with dry processing steps (see Fig-
ure 4-5). This division between wet and dry processing
distinguishes long staple from short staple spinning; no
wet processing occurs in short staple spinning until the
yarn is desized, scoured, and bleached at the finishing
mill. Information specific to long staple systems is there-
fore covered in Section 4.12, "Finishing." This is appro-
priate because scouring, dyeing, and finishing of wool
are commonly done when wool is in the form of raw
stock fiber, sliver, tops, as well as yarn and fabric. Sec-
tion 4.12 includes a major subsection on wool wet
processing.
Many of the same pollution prevention techniques pre-
sented below for short staple are equally applicable to
the dry steps in wool spinning.
4.6.1.4 Short Staple Spinning
The majority of yarn in the United States is produced
using short staple spinning. Figure 4-6 shows the steps
in the short staple spinning process. Pollution preven-
tion in this process primarily focuses on three items:
• Fiber waste from cleaning and other processing
operations.
• Packaging wastes.
• Additives such as tints, antistatics, and lubricants that
are applied during spinning and that must later be
removed.
Raw, Greasy Wool
Sorting, Selecting, and Blending To Suit Type of Yarn Required
Opening Out and Loosening of Fiber Packages
Scouring To Remove Grease and Suint (Sheep's Dried Perspiration)
and Carbonization (If Necessary) To Remove Cellulose Impurities
(in Lap Form)
Carding
Condensing
y (in Roving Form)
Spinning on Mule Machine
Into Woolen Yarns
Backwashing (scouring)
I (in Sliver Form)
Gilling
^ (in Sliver Form)
Backwashing
!• (in Sliver Form)
Gilling
J, (in Sliver Form)
Combing
4> (in Sliver Form)
Gilling
I (in Sliver Form)
Wool Tops
I
Drawing and Doubling
(Several Stages)
I (in Roving Form)
Spinning by Flyer, Cap, Ring or
Mule Machine Into Worsted Yarns
Figure 4-5. Stages in the manufacture of yarns for long staple
spinning (42).
Most fiber waste comes from cotton processing because
cotton is less pure than synthetics upon arrival at the
mill. Trash, immature fibers, and other impurities must
be removed from cotton before processing. In other
respects, however (e.g., packaging waste), cotton and
synthetics are similar in terms of process waste.
Spinning operations have already achieved dramatic
improvements in waste reduction, mainly for economic
reasons. Successful waste reduction is a common fea-
ture of commodity operations (e.g., yarn spinning),
where raw material cost and utilization are closely re-
lated to profitable performance. The opposite is true with
very high value-added products (e.g., coated fabrics),
where raw material cost and waste are minor overall
factors. The economic incentive to conserve and reuse
raw materials is extremely low, and the economic incentive
155
-------
Raw Staple Rber
V
Opening
V
Cleaning
y
Carding
Lapping (Combed Cotton Yarns)
Combing (Combed Cotton Yams)
Drawing
V
Drawing
Drawing (Three Process Yarns)
V
Open-End
Spinning
Roving
Y
Ring Spinning
Winding
I
Packing
Figure 4-6. Stages In the manufacture of yarns for short staple
spinning.
to make the best product regardless of cost or waste is
much greater.
Although most mills have extensive waste minimization
programs, spinning still generates a substantial amount
of waste. A 1986 U.S. Department of Energy study
estimated that the total amount of fiber waste in the
United States from polyester and cotton spinning opera-
tions is 45 million pounds per year (43). In one company
with six spinning operations, the waste was equivalent
to 70 bales of fiber per day (44). According to a survey
of fiber waste in spinning mills, over 40 percent of this
waste is controllable using management practices de-
scribed in this section (44).
4.6.2 Types of Waste Associated With
Spinning
Although spinning operations generate many types of
waste, the main categories are (45):
• Process waste.
• Controllable-cause waste.
• Solid wastes such as packing materials (notably
polypropylene bale wrap) and bale straps (plastic or
metal).
4.6.2.1 Process Waste .
Process waste is related to the manner in which staple
fibers are processed during spinning. This waste can be
further characterized according to its potential for reuse:
• Reworkable waste: Refers to good, clean fibers that
can be fed directly back into the opening line through
a designated waste hopper. These fibers originate
from nearly every process in the spinning mill. They
are collected, delivered to waste containers or air
handling systems, then returned to the opening line.
These fibers have their full value, and standard prac-
tice in nearly every spinning mill is to have at least
one waste hopper for reworkable wastes in the open-
ing line.
• Nonreworkable waste: Is generally produced in
cleaning processes (e.g., opening, cleaning, carding).
It also may contain various amounts of soiled or dam-
aged reworkable waste.
• Hard waste: Refers to yarn that has been sized.
These fibers are very difficult to open and reuse in
the normal spinning process.
Most mills employ efficient recovery and reuse systems
for reworkable wastes, and many also find suitable
reuse opportunities for other types of process waste.
4.6.2.2 Controllable-Cause Waste
Controllable-cause wastes are those attributed to up-
sets or departures from normal operating procedures,
such as (44):
• Worker error or mistake, or failure to follow procedures.
• Rejected materials, off-specification materials, and
failed QC.
• Equipment malfunctions.
• Poor housekeeping.
• Improper method or procedure.
Such wastes are considered controllable because they
can be avoided through closer attention to factors such
as equipment maintenance, operating conditions, and
QC procedures.
4.6.2.3 Solid Waste
Solid packaging wastes include bale wrap, cones,
cases, and strapping. These wastes are discussed later
in this section and in Section 1.2.3, "Solid Wastes."
156
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4.6.2.4 Additives
In addition to the wastes discussed above, another im-
portant issue for spinning operations is chemicals that
are added during spinning and that can affect operations
later in the production process. Additives such as tints
and lubricants are often applied in the spinning opera-
tion with implications for later stages of the production
process (e.g., during preparation for printing, dyeing,
finishing). Additives are discussed under the processes
in which they are removed (e.g., Section 4.9, "Prepara-
tion") and in Section 4.17, "Globalization of Pollution
Prevention."
4.6.3 Pollution Prevention in Short Staple
Spinning
The amount of waste generated from short staple spin-
ning depends on the cotton grade used as input and the
intended quality level of the spun yarn. To produce good
yarn, the nonlint content (trash) of the raw fiber must be
removed, and, as part of the process, a certain amount
of lint is also removed. Over the years, the nonlint
content of raw cotton has decreased significantly. Before
1960, the waste content of raw cotton averaged from 2
percent for the best grades, such as strict good middling
(SGM), to over 10 percent for lower grades, such as strict
good ordinary (SGO) (45). As the nonlint content in the
raw cotton has decreased, the amount of nonreworkable
waste generated in spinning has also declined.
The decrease in'the nonlint content of raw cotton is
partially due to mechanical harvesting machines, which
became popular in the 1950s to 1960s. These machines
reduced the nonlint content in cotton by automating
aspects of the cotton picking process. Lint cleaners also
have been added to gins over the years. These "fine"
cleaners remove small particles of waste after the lint
and seeds are separated in the gin stand. Before seed/
fiber separation, cleaning was very inefficient, and only
the largest trash particles (e.g., stems, leaves) could be
removed. After the separation of lint from seeds, the lint
cleaners can remove finer trash efficiently. Most gins
now have one to three stages of these fine cleaners,
which remove more trash, and thus give reduced nonlint
content for the fiber bales going to the spinning mill.
The nonlint content of the raw cotton itself has declined
through improved agricultural and ginning techniques,
including the development of better strains of cotton.'
Figure 4-7 shows historical data on the nonlint content
of various cotton grades from the 1950s through 1986.6
Cleaning waste is fiber deliberately removed from the raw
cotton at the spinning mill to increase the quality of the
cotton stock and thus obtain the desired yarn properties.
Most of this originates from opening, cleaning, carding,
and combing and may amount to between 5 percent and
20 percent of the raw fiber (44). In U.S. mills with good
waste control, 5 percent is the typical upper limit.
Sweeps, fly, and invisible (unaccounted) waste amounts
to 1.5 percent in the best mills but may range as high
as 9 percent in poorly operated mills. The rest of the
waste results from neglect, old equipment, or poor
work practices (44).
In addition to improving the raw cotton itself, process
engineering has led to other changes that have reduced
spinning mill waste. The elimination of such processes
as pickers, roving in the rotor spinning process, and
winding as a separate process has prevented waste. In
addition, major improvements have been made in open-
ing, cleaning, carding, drawing, and spinning. Sophisti-
cated waste handling systems are now available to
capture waste using vacuum and pneumatic handling.
The net result is that nonreworkable waste generation from
spinning processes has steadily declined, as follows.7
1930s
1950S
1990s
15 percent
10 percent
3 to 5 percent
Spinning mills now typically produce between 3 percent
and 5 percent nonreworkable waste, depending on the
grade of.cotton they run and the product they make.
Modern reclamation equipment can reclaim some lint from
this nonreworkable waste, ultimately yielding 1.5 per-
cent or less waste to discard. Many mills do better than
the 1.5-percent figure, while a few of the worst mills are in
the 2.0-percent range. All waste, except for "hard" waste,
can be reused internally if properly reprocessed (44).
An ever-increasing ability to reuse and recycle waste
has accompanied increased waste reduction. Markets
have developed for various waste products, and sepa-
ration techniques for reprocessing nonreworkable waste
now can recover most of the waste as reusable lint.
The state-of-the-art pollution prevention technique for
handling nonreworkable waste is to collect it using vac-
uum capture at its source. Capture and recovery points
include lost ends in roving or sliver, air handling filter
systems, cards, draw frames, carding and cleaning waste,
and comber noils. This waste is carried by air to a
system that separates lint from nonlint. The amount of
recovered lint depends upon the cotton grade. Of the 3
to 5 percent total waste, typically only 1.5 percent actu-
ally survives as nonlint waste to be discarded. The
recovered lint (fiber) is fed back into lower quality prod-
ucts, or at a very low level into the same product opening
line. The 1.5 percent that is trash is sold for several other
reuse applications. One example is padded mailing en-
velopes, which are often stuffed with this material. An-
' See footnote 5.
See footnote 5.
157
-------
1947 1957 1967 1977
1947 1957
1967
1977
10
8
6
4
2
0
1947 1957 1967 1977
1947 1957 1967 1977
1947 1957 1967 1977
1947 1957 1967 1977
,' „ 'ill! J '.,ii!i. ii,,!ii; S, ,i
Cotton is graded according to the following
grading system (best to worst):
SGM = Strict Good Middling
GM = Good Middling
SM = Strict Middling
M = Middling
SLM = Strict Low Middling
LM = Low Middling
SGO = Strict Good Ordinary
GO = Good Ordinary
BG = Below Grade
Figure 4-7. Average percent Shirley Analyzer nonllnt content of white cotton grades (see footnote 5).
158
-------
other common reuse opportunity is to compress the
material using a two-stage hydraulic ram system into
extremely high-density cylindrical pellets about 2 inches
in diameter and 2 inches long to use as boiler fuel.
4.6.4 Other Waste Issues
In addition to the fiber waste discussed above, two other
waste issues are important in spinning operations:
• Additives added during spinning that must be re-
moved later.
• Solid packaging waste.
Additives (e.g., tints, lubricants) are often applied in the
spinning operation and affect later preparation stages
(printing, dyeing, finishing). Methods for managing these
are discussed under the processes in which they are
removed (e.g., Section 4.9, "Preparation") or in Section
4.17, "Globalization of Pollution Prevention."
Solid packaging wastes, including bale wrap, cones,
cases, and strapping, are discussed in Section 1.2.3,
"Solid Waste." Because of large volumes, mills should
use plastic reusable cones to minimize waste from these
sources and should reuse yarn cases. An even better
solution than reusable yarn cases is the palletized
shrinkwrap form of yarn packaging, which allows work-
ers to see the yarn through the plastic shrinkwrap. When
workers can see the yarn, they tend to handle it more
carefully, thus reducing the amount of dirty and dam-
aged yarn, and associated waste.
4.7 Slashing and Sizing
The following table introduces pollutants and waste
streams discussed in this section, as well as pollution
prevention activities suggested for each.
Pollutant or Waste
Stream
Pollution Prevention
Actions Described
in This Section
Comments
4.7, Slashing and Sizing (General)
Polymeric sizes in
general
Global views
Size add-on
optimization (use
minimum required
amount)
Incoming raw
material QC
Minimization of
discards
Equipment
maintenance
Proper storage,
handling, and
employee training
Facility design
Solid capture;
housekeeping
Reduction of size
add-on at weaving
(and perhaps loss
of weaving
efficiency) ensures
pollution reduction
at the desizing
operation
Pollutant or Waste
Stream
Pollution Prevention
Actions Described
in This Section
Comments
BOD, COD
Metals
Air and water toxics
Fiber lint and yarn
waste
Selection and
handling of size
Incoming raw
material QC
Incoming raw
material QC
Segregation, capture,
and reuse for fuel
Reduction at the
slashing operation
and at the desizing
operation
Packaging
Supplier involvement;
purchasing
specification for
reusable IBC or bulk
packaging
Avoid bags
4.7.1, Unit Process Description
General polymeric
size pollution
Understanding of the
function and
applications of warp
size
Improved process
control of
temperature, speed,
add-on, tension, and
moisture (dryness)
Facility design (e.g.,
mix kitchen, pumps,
mix tanks, and scales)
Equipment design,
maintenance, and
operation
QC improvement and
prevention of loom
stops
Polymeric sizes in
general
4.7.2, Warp Size Types and Properties
Global views
Size add-on
optimization (use
minimum required
amount)
Incoming raw
material QC
Minimization of
discards
Equipment
maintenance
Proper storage,
handling, and
employee training
Facility design
Solid capture;
housekeeping
Selection and
handling of size
Incoming raw
material QC
Reduction of size
add-on at weaving
(and perhaps loss
of weaving
efficiency) ensures
pollution reduction
at the desizing
operation
BOD, COD
Metals
Air and water toxics
Fiber lint and yarn
waste
Incoming raw
material QC
Segregation, capture,
and reuse for fuel
159
-------
Pollutant or Waste
Stream
Pollution Prevention
Actions Described
in This Section
Comments
Pollutant or Waste
Stream
Pollution Prevention
Actions Described
in This Section
Comments
Packaging
Supplier involvement; Avoid bags
purchasing
specification for
reusable IBC or bulk
packaging
4.7.3, Desizlng
BOD (starch)
Size (synthetic)
Process alternatives,
including oxidative or
acid desizing
Segregation and
recovery for reuse
4.7.4, Identification of Wastes and Pollutants
Size packaging
materials
Unused portions of
mixes
Equipment dean up
BOD
Aquatic toxicity
Fiber lint and yam
waste
Size itself
Buying in bulk or
IBCs; work practices;
monitoring/auditing
packaging materials
Proper planning and
scheduling;
monitoring/auditing
dumps
Planning and
scheduling; teflon-
coated dry cans to
reduce fouling; better
process
monitor/control;
monitoring/auditing
cleaners
Alternative size
materials and
auxiliaries; proper mill
conditioning and
controls to reduce the
need for additives
Alternative recipes;
monitoring/auditing
and reducing
machine cleanup
events; proper mill
conditioning and
controls; timely
scheduling from
weaving to desizing
to reduce the need
for biocides; incoming
material
prescreening/QC
Bar code tracking to
improve efficiency
and reduce waste;
monitoring/auditing
these wastes
Segregation for
recycle and recovery;
proper size selection;
better process control
and add-on monitor;
proper fabric design
to reduce the need
for size and weighter;
work practices; audits
Global views are
important; changes
in sizing practice
produce pollution
reduction at desiz-
ing operations;
correct risk/benefit
determination is
important
General
Maintenance;
monitoring; control
and optimization of
processes
Warp size (or size) is a chemical mixture applied to
fibers that will undergo weaving (but not knitting) opera-
tions. Size improves the strength and bending behavior
of yarn, allowing weaving operations to continue with
less breakage and fewer stoppages than would be the
case with untreated fibers. Size is applied only to the
warp (lengthwise) yarns because they are under the
most mechanical stress in weaving operations; the weft
yarn is not coated with size. The operation that applies
size to the yarn is termed slashing. Warp yarns for cotton
and cotton blends have 10 to 15 percent (by weight of
goods) added as size, while filament synthetics require
3 to 5 percent by weight of sizing. Size is removed from
the fabric when the weaving operation is complete, in an
operation called desizing, and this can contribute high
pollution loads to textile effluent.
Many opportunities for pollution prevention exist in warp
sizing operations.
• Modern weaving machines run at high speeds and
therefore place extreme demands on yarns in the
loom. Proper warp sizing is a crucial factor in fabric
quality and in preventing loom stoppages, which
lower weaving efficiency. For effective pollution pre-
vention, a slashing operation must look beyond weav-
ing performance to the desizing operation and the
pollution contributed by size at that stage. A global
attitude about size is required for pollution prevention
because the size will be removed at another location.
Mills should remember that everything that is put on
as size will eventually become waste, so they should
be conservative in using and specifying size. Size
add-on should be monitored and correlated with ac-
tual production performance. In many cases, size use
may be reduced without affecting the desired results
in the weaving operation.
• QC of incoming raw material is important for size.
Mills should implement checks for metals, toxic or-
ganics (e.g., biocides), and other potential contami-
nants. Only the correct amount of size mix should be
prepared to avoid dumping unused portions. Similar
styles should be scheduled to run sequentially to
avoid unnecessary cleaning of size tanks and other
equipment, as well as excessive discards of unused
size. Excessive and unnecessary additives in size
mixes should be eliminated. If additives are used,
only those that will not produce toxic or offensive
waste streams during desizing should be selected.
160
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Slasher and mix area equipment should be main-
tained to avoid leaks and spills. Add-on levels should
be carefully monitored and controlled to use the mini-
mum amount of add-on necessary to accomplish the
task.
• Fiber lint and yarn waste should be segregated.
Packaging should be reduced by specifying bulk or
IBCs for size. Mix kitchens, slashers, and work areas
should be monitored for proper chemical handling
and work practices. Conditions in the; weave room or
storage areas should be controlled to avoid prob-
lems. Facilities should be designed so that pipes from
the mix kitchen to the size boxes are of minimum
length to minimize the quantity discarded during
changeover and cleanup. Only nontoxic, safe clean-
ing agents should be used to clean equipment such
as tanks, pumps, lines, size boxes, cans, and lease.
As much waste as possible should be captured in
solid form for landfill or other appropriate disposal
(not disposed of down the drain). Machine cleaning
supplies should be accounted for, and the required
frequency and severity of cleaning for slasher and
mix area components (containers;, utensils, mix
tanks, pumps, lines, working area) should be moni-
tored. Employees should be trained in proper clean-
ing procedures.
Size serves no long-term purpose on the fabric, only a
transitory purpose for weaving. Every year, the textile
industry uses and discards huge quantities of warp size.
In the United States, consumption is estimated at ap-
proximately 200 million pounds per year.8 Less than 10
percent of this is recycled; the rest is disposed of in the
effluent stream. This makes size disposal one of the
largest industrial waste streams in U.S. manufacturing.
Size mixes have different properties, so size selection
is a crucial step in achieving the desired results in
weaving and size removal operations. Important proper-
ties of sizing compounds are the swelling temperature
and the water solubility. With the introduction of high-
speed air-jet weaving machines, size drying speeds are
also important. These machines have made high-speed,
high-pressure, low-wet-add-on sizing ranges popular
and resulted in the introduction of low-viscosity, high-
solids size formulations.
4.7.1 Unit Process Description
To ensure proper performance of yarns in a loom, stiff-
ening agents and lubricants are added to the warp
yarns. The size improves the toughnesis of the yarn and
improves its bending behavior. As a result, abrasion,
8 Robinson, G., and B. Smith. Personal communication between
George Robinson, DuPont Company, Charlotte, NC, and Brent
Smith, Department of Textile Chemistry, North Carolina State Uni-
versity, Raleigh, NC.
fuzzing, static buildup, stretch, breaking, creep, entan-
glements, shedding of lint, and other undesirable events
are suppressed in the weaving process. Modern weav-
ing machines run at high speeds and place extreme
demands on the yarns in the loom. Proper warp sizing
is a crucial factor in attaining final fabric quality and in
preventing loom stops, which lower weaving efficiency.
Warp size is added to a sheet of warp yarns using
pad/dry techniques in a large range called a slasher,
which comprises:
• A yarn creel with very precise tension controls.
• A yarn guidance system.
• A sizing delivery system, usually involving tank stor-
age and piping to the size vessels.
• One or more dips of the yarn sheet in size solution.
• Drying of yarns on hot cans or in an oven.
• A lease that separates yarns from a solid sheet back
into individual ends for weaving.
In addition, sizing operations require ancillary equip-
ment such as a mix kitchen with scales, mix tanks,
pumps, and plumbing, as well as a precise slasher
control system, which usually features temperature,
speed, density, tension, and moisture monitors. *
4.7.2 Warp Size Types and Properties
Size is a mixture of primary and auxiliary chemicals. The
subsections below describe the chemical makeup of
typical size mixtures.
4.7.2.1 Primary Component of Size
The type of size used depends on the yarn type, weav-
ing process (e.g., loom type, speed) and historical tradi-
tion and experience in the textile facility. Three main
types of size are currently used:
• Natural products (starch): Starch is the most common
natural size and the most common size overall. It can
be derived from a variety of substances, but corn and
potatoes are preferred. Starch is used mainly for cot-
ton products and other natural fibers.
• Fully synthetic products: Synthetic sizes include poly-
vinyl alcohol (PVOH or PVA), polyvinyl acetate
(PVAc), polyacrylic acid (PAA), and polyester (WD).
• Semisynthetic products (blends): Semisynthetic sizes
or blends include modified starches, starch ethers,
starch esters, carboxymethyl cellulose (CMC), hy-
droxyethyl cellulose (HEC), and carboxymethyl
starch (CMS).
See Table 4-27 for a listing of sizes used for various
fibers and Table 4-28 for a more detailed classification
of size types. Table 4-29 lists environmental advantages
161
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Tab!o 4-27. Sizing Materials Used for Filament Yarns (28)
Fiber Type Basic Size
Nylon Polyacrylic acid
PVA
Glass PVA
Dextrins
Amylose derivatives
Blends
Acetate Stymer (styrene-maleic anhydride copolymer)
Gelatin
Viscose rayon PVA
Amylose derivatives
CMC
Blends
Polyester Acrylic copolymers
Alkali-soluble polyvinyl acetate
Linear polyester
Tablet 4-28. Categorization of Spun Yarn Sizing Materials (28)
Starches: Corn, Potato, Tapioca
Unmodified—pearl
Acid-modified. 20-60 fluidity
Oxidized, several fluidities
Daxtrinized (British gum)
Derivatized
Acetate
Hydroxyethyl ether
Acrytate
Styrene
Cross-linked
Cattonlc
High amylose
Low amylose (waxy)
PVA
Fully hydrolyzed
Partially hydrolyzed
Other
CMC
Blends
Other polymers
and disadvantages of alternative starches. Specific
types of size used in textile weaving are described below.
Starch
Starch is the most common primary size component,
accounting for approximately two-thirds of all size
chemicals used in the United States (130 million pounds
per year). Starch offers good performance on natural
fibers and is often used in a blend with synthetic sizes
for coating natural and synthetic yarns. A major problem
with starch size is the inability to reuse or recycle the
Table 4-29. Environmental Advantages and Disadvantages of
Alternative Synthetic Sizes (37)
Size
Advantages
Disadvantages
CMC
PVA
Can reuse solutions
Washes off with cool water
Good adhesion
Supports mildew
Cost
Cost
Tough films
Can mix with starch
Washes off easily with hot water
PAA Washes off with alkali
Good adhesion to nylon and
synthetics
• Can control stiffness by
copolymerization
WD Good adhesion to polyester
Washes off with very hot water
Cost
Cost
Can precipitate
and cause spots
size because of degradation of the starch to various
sugars during the desizing process.
Polyvinyl Alcohol
PVA accounts for much of the remaining size consumed
in the United States (70 million pounds per year). PVA
offers excellent mill performance when processing poly-
ester/cotton goods and pure cotton fabrics and washes
out completely to facilitate uniform dyeing. The strength,
adhesion, viscosity, and other properties of PVA are
affected by the degree of hydrolysis (the percentage of
acetate groups replaced by hydroxyl groups). PVA can
be used as size in either 100-percent pure form, or in
blends with natural sizes such as starch. A typical blend
formulation contains 50 to 95 percent PVA, depending
on the type of fabric used and other processing pa-
rameters. For spun yarn, high-viscosity PVA is used to
bind the surface fibers and coat the yarn with a continuous
film to suppress neps. In this application, a fully hydro-
lyzed PVA/starch mixture is usually employed. For fila-
ment fibers, low-viscosity partially hydrolyzed PVA is
used to penetrate the yarn to prevent fiber splitting and
breaking.
Sodium Carboxymethylcellulose
CMC is an anionic polyelectrolyte that is soluble in either
cold or hot water. The U.S. industry uses approximately
5 million pounds of CMC per year. CMC size is used
primarily for polyester/cotton and polyester/rayon
blended yarns. For sizing pure synthetic fibers such as
polyester, competing sizes provide better adhesion,
stronger film, less shedding, and less sensitivity to mois-
ture than CMC size. CMC and acrylics might compete
with PVA, but these sizes do not provide the necessary
strength for all applications. Also, at high humidities,
CMC sizes do not perform as well as other alternatives.
-------
Hydroxyethylcellulose
HEC size is available in water-soluble or alkali-soluble
grades with a range of properties including wide-ranging
solution viscosity. Alkali-soluble HEC is used in textile
sizing, although in negligible quantities.
4.7.2.2 Size Auxiliary Chemicals
Sizes generally consist of mixtures of the above primary
chemicals plus additional auxiliary chemicals added to
improve weaving performance, enhance the stability of
the size or sized yarn, distinguish between sizes, and
for many other purposes.
Auxiliaries used in sizing mixtures include:
• Adhesives and binders: To assist in binding the size
to the yarn. Examples: natural gums (locust bean
gum, tragasol, but not starch), gelatin, soya protein,
casein, acrylates, PVA, CMC.
• Antistatic agents: To suppress static in high speed
weaving.
• Antisticking agents: To reduce fouling of dry cans
and guide rollers. Examples: waxes, oils, sulfated
tallow, pine oil, kerosene, Stoddard solvent.
• Biocides (preservatives): To improve shelf life of
woven goods. Example: orthophenyl phenol (OPP).
• Defoamers: To suppress foam in locations where
process water is very soft. Example: zinc and calcium
chloride, light mineral oil, isooctyl alcohol but not sili-
cones.
• Deliquescents: To protect against overdrying. Exam-
ple: zinc and calcium chloride, polyalcohols (PEG),
glycerine, propylene glycol, diethylene glycol (DEG),
urea.
• Emulsifiers, dispersants and surfactants: To stabilize
size mixtures during application and assist in desizing
operations. Example: nonionic ethylene oxide com-
pounds.
• Humectants: To protect against drying.
• Lubricants and softeners: To improve the bending
and frictional characteristics of the yarns. Examples:
fats, waxes, oils, tallow, sulfated tallow, buty]
stearate, glycerine, mineral oil.
• Penetrants: To assist in penetration of size on fila-
ment yarns but not spun yarns.
• Release agents: To facilitate removal of size during
desizing.
• Thinning agents: To increase penetration (similar to
penetrants). Examples: enzymes, oxidizers, perbo-
rates, persulfates, peroxides, chloramides.
• Tints: To identify warps.
• Weighters: To increase the density of woven yarn.
Example: clay.
Lubricants are grouped in two general classes: saponi-
fiables and unsaponifiables. The unsaponifiable lubri-
cants are considered the best friction reducers and
include crude-scale paraffin wax and refined paraffin
wax. Removal of these during desizing, however, re-
quires added surfactants, which have high aquatic
toxicity (see Section 2.2.6, "Aquatic Toxicity")- Saponifi-
ables include fats and fatty components such as fancy
tallow, hydrogenated tallow glycerides, and fatty esters.
These compounds can also be used as emulsifiers for
the unsaponifiables.
Any of these additives that are present in the size mix-
ture will later be removed in wet processing (prepara-
tion, desizing, and scouring), and thus all of these
materials will appear in waste streams from desizing
operations. Undesirable materials (e.g., zinc salts, OPP)
are generally not used on domestic goods but regularly
appear in imported fabrics. This is an important point in
the process at which to perform QC for raw material
screening in textile operations (see Section 3.12, "Raw
Material Prescreening Before Use").
4.7.3 Desizing
The desizing process produces a high-volume waste
stream. Desizing waste deserves attention because es-
sentially all size chemicals that are removed enter the
waste stream, and the amount of chemicals removed
during desizing is significant. Typically, 6 percent or
more of the weight of the goods is added as size, only
to be removed and discarded in the desizing operation.
Desizing of starch is usually performed using enzymes
to solubilize the starch, followed by thorough washing of
the fabric to remove the size and desizing chemicals.
Alternative procedures include the use of acids or oxi-
dizers to degrade the starch. These procedures are not
as common as the use of enzymes because of the
potential for cotton fiber damage. Acid desizing hydro-
lyzes the starch, rendering it water soluble. Enzyme
desizing uses animal or vegetable enzymes to decom-
pose starch to a water-soluble form. Because the starch
is degraded, recycling is impossible; therefore, the
desizing waste must be disposed of in the effluent.
Synthetic sizes are usually removed with hot water
washes, although alkali is sometimes used to increase
solubility. The removal process does not degrade syn-
thetic sizes, so they can potentially be recovered for
reuse as a sizing agent.
4.7.4 Identification of Wastes and Pollutants
Sizing and desizing operations contribute to BOD and
aquatic toxicity in different amounts, depending on the
exact makeup of the size mixtures the mill uses. Addi-
163
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tional wastes associated with sizing and desizing in-
clude size packaging, dumps of unused size mixtures,
and equipment cleaning wastes.
4.7.4.1 BOD
Starch desizing contributes relatively high BOD loadings
to the effluent compared with synthetic desizing. Typical
starch sizes have 5-day BODs of 500,000 to 600,000
ppm, while alginates and modified starches have BODs
of 100,000 to 500,000 ppm (11). Table 4-30 lists BODs
Table 4-30. BODs of Various Warp Sizes (11)
Size BOD (ppm)
PVAc
PVOH
PVOH/CMC (3:1)
CMC
HEC
Starch/PAA (5:4)
Alginate
Starch ether
Starch/PVOH (5:1)
Starch
10,000
10,000-16,000
17,500
30,000
30,000
395,000
360,000
360,000
405,000
470,000
Table 4-31. BODs of Various Size Materials (11)
Size Material BOD (ppm)
Ahco nylon wax size
B-2 gum (starch dextrins)
Brytex gum 745 (starch)
CMC
Elvacet (PVA)
Elvanol 72-60 (PVOH)
Globe Easyftow starch
Hydroxyethyl cellulose (HEC)
KD gum (starch)
Keofilm No. 40 (starch)
Momingstar starch
Nicol starch
Pearl (comstaroh, No. 173 and PT)
Penrod gum 300 (hyroxy starch ether)
FTTC gum (starch-urea)
Starch No. 450
Sodium alginata
Wheat starch
Ambertex M (starch paste)
340,000
. 610,000
610,000
30,000
10,000
10,000-16,000
650,000
30,000
570,000
50,000-550,000
470,000
570,000
500,000
360,000
120,000
460,000
360,000
550,000
20,000
of various sizes, and Table 4-31 reports BODs of a range
of size materials. Synthetic sizes contribute much lower
BOD loadings than starches, ranging from 10,000 to
30,000 ppm. These BODs are approximately 15 to 60
times lower than for starch, lowering the BOD by well
over 90 percent. If the synthetic size is recycled, BOD
loadings drop even lower for an overall reduction (com-
pared with starch) of over 99 percent (11).
Auxiliary components of the size mixture can also affect
BOD levels. Humectants, lubricants (waxes and oils),
antistatic compounds, biocides, glycerine, and welters
contribute up to 10 or 15 percent of the total BOD load
from size mixtures. Of these, humectants and lubricants
contribute the most, typically 2 to 5 percent of the total
(11). Typical BODs and aquatic toxicities for additives
are found in Table 4-32.
4.7.4.2 Toxicity
Toxicity contributions derive mainly from the auxiliary
chemicals added to the size mixture. Surfactants and
biocides commonly add to aquatic toxicity.
4.7.4.3 Other Wastes
In addition to the size/desize chemicals removed from
textiles, sizing and desizing operations generate addi-
tional wastes that deserve attention, including:
• Packaging materials for size: Size is commonly
shipped to the textile mill in 80-pound bags. Based
on the amount of size that weaving operations con-
sume, these bags can constitute a major solid waste
source. In one operation, three slashing units con-
sumed over 37,000 bags of size per year.
• Dumps of unused portions of size mixes: Size
batches are mixed in the amount needed for the
upcoming production run. Occasionally, excess size
is mixed or goes unused. Because starch-based size
mixtures cannot be stored, excess may be dumped
hot to the sewer.
• Machine cleaning and maintenance: Cleaning and
maintenance of sizing equipment may be performed
with solvent-based cleaning agents. Wastes from
Table 4-32. BOD and Aquatic Toxicity of Warp Size
Additives (11)
Additive
Surfactants
Urea
Glycerine
Oils and waxes
Biocide
DEG
BOD (ppm)
10,000 to 1,000,000
90,000
640,000
100,000to 1,500,000
Test fails
60,000
Toxicity L.CSO (ppm)
<1 ppm to 28 ppm
>1 ,000 ppm
>1 ,000 ppm
Varies
High
>1 ,000 ppm
164
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cleaning and maintenance operations include mate-
rials such as wipes, rags, and discarded filters.
• Fiber lint and yarn waste: Desizing operations scour
fabric to remove sizing chemicals and may remove
substantial amounts of lint and yarn waste.
4.7.5 Pollution Prevention Measures
Pollution prevention measures for sizing and desizing
operations focus on proper fabric design, operating
equipment to minimize sizing requirements, selection of
appropriate size chemicals, proper size mixing, and
proper worker training/attitude.
Sizing is one example where pollution prevention activi-
ties must be undertaken within one unit operation (siz-
ing) while another unit operation (desizing) enjoys the
benefits (i.e., reduced pollution). This can be especially
challenging in situations where the same company does
not perform both the sizing and the desizing, though
even within companies, difficulty may arise in achieving
cooperation between departments on pollution preven-
tion issues. In these situations, a proper pollution pre-
vention strategy should stress documentation of policies
and practices, communication among departments or
between companies, and incentives. This extends to
globalization of the pollution prevention strategy requir-
ing better information exchange between consumers,
designers, managers, and suppliers, as discussed in
Section 4.17.3.2.
4.7.5.1 Size Selection
Significant reductions in pollution are achievable
through careful selection of the warp size mixture. De-
termining the most appropriate size for a particular
weaving operation is complicated, partly because of the
multitude of different sizing materials that are available
to the textile manufacturer. Different fiber types, weaving
looms, cost requirements, fabric designs, and pollution
characteristics are just some of the factors the manufac-
turer needs to balance in selecting a size.
The most accurate means of evaluating a size formula
involves in-plant testing. Certain sized yarn charac-
teristics can indicate overall weavability, including elas-
ticity, elongation, tensile strength, resistance to abrasions,
continuity, and consistency. These can be accurately
evaluated by testing samples in the laboratory, following
test procedures developed by organizations such as the
Institute of Textile Technology.
The mechanical and operational characteristics of the
sized yarn must be considered as only part of the overall
selection requirements. Cost of the size is an important
element, and the polluting characteristics must also be
considered. A size that has inherently low pollution, or a
size that can be recycled or reused, should be
given high priority, in addition to mechanical and cost
considerations.
Two large gains in pollution reduction come from choos-
ing synthetic sizes with inherently lower BOD levels and
sizes that have the ability to be recycled and reused.
The combination of moving from high-BOD starch to a
lower BOD synthetic that can be reused can reduce
BOD output by nearly 100 percent. Several warp size
alternatives are available, as noted above (i.e., starch,
PVA, CMC, PVAc, PAA, and polyester). These materials
differ considerably in their BOD and COD content, as
well as the degree to which they are degraded during
desizing. PVA and CMC are low-BOD, recoverable sizes
and hence should receive serious consideration as al-
ternatives to starch.
As is the case with surfactants (see Section 4.4.2.5)
some high BOD sizes tend to be easy to treat and some
low BOD sizes are more likely to pass through waste
treatment systems. Unlike low BOD surfactants, unde-
graded, low BOD warp sizes (e.g., PVOH) that pass
through waste treatment systems have relatively little
harmful effect on the environment. With warp sizes,
therefore, it is not as clear which type is preferable. The
consideration is the use of a natural, renewable, biode-
gradable material (i.e., starch) versus a synthetic mate-
rial that can be recovered (but usually is not in practice).
Another consideration during size selection should be
the nature of additives in the size mixture. Surfactants
and biocides contribute to BOD, and their use should be
examined in light of the facility's overall pollution preven-
tion goals. Additives can also interfere with the recy-
clability of sizes.
4.7.5.2 Size Recycling/Recovering
Recovery of synthetic (PVA) size can be performed
using membrane filtration equipment such as that
shown in Figure 4-8. Size recovery is not widely prac-
ticed in the textile industry, however, for a variety of
reasons. A few successful size recovery systems are
currently in operation, but these systems can recover
only certain types of sizes, notably PVA. As indicated,
PVA accounts for approximately one-third of total size
consumption in textiles. The bulk of size used is starch,
which degrades during desizing and cannot be recovered.
Currently, less than one-third of all PVA is recovered.
Several technical and business barriers prevent further
recycle, including the practice of mixing PVA with sizes
that inhibit recovery, the high expense of shipping recov-
ered PVA concentrate solutions, high capital cost of
recovery equipment, commingling of goods containing
different sizes at the desizing plant, and lack of under-
standing of recovery potential.
Thus, for several valid reasons, the textile industry makes
limited use of size recovery. This is equivalent to thou-
165
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sands upon thousands of tons of intentionally created
waste, making it (in addition to water, salt, and cutting
room waste) one of the highest volume waste materials
in textile manufacturing, and perhaps all United States
manufacturing. To increase size recycling requires 1)
removing logistical and technical barriers to recycling
and reclamation of sizes, 2) providing more incentives
for recovery, 3) developing fabric-forming machines and
processes that require minimal amounts of sizes, and 4)
designing yarns and fabric structures that require
less size and lubricant to produce.
Nonintegrated mills face substantially greater barriers to
recycling size because sizing and desizing operations
occur at different firms. Reusing or recycling requires the
sizing and desizing mills to coordinate activities, includ-
ing information transfer (e.g., types of size applied,
quantities recycled) and physical activities (e.g., trans-
port of goods, quality testing, financial arrangements).
The benefits of recycle accrue to the desizing facility,
which recovers a waste that has economic value, while
the costs accrue to the sizing facility, which absorbs the
higher costs of size reformulation.
4.7.5.3 Chemical and Process Alternatives
Numerous auxiliary chemicals may be added to the size
mixture, including adhesives, binders, antistatic agents,
antisticking agents, biocides, defoamers, deliquescents,
emulsifiers, dispersants, surfactants, lubricants, soften-
ers, thinning agents, tints, and weighters. These addi-
tives can contribute significantly to BOD, COD, aquatic
toxicity, and the volume of wastes associated with sizing
and desizing operations. Reported BOD values and
aquatic toxicities of several additive materials are sum-
marized in Table 4-32.
In most cases, these additives are added to overcome
or prevent the occurrence of specific problems that may
arise during slashing, weaving, or storage. Often, ad-
dressing these concerns using mechanical or other non-
chemical means may be possible, thus avoiding the use
of chemical additives. For example:
• Air-conditioning and humidification systems can pre-
vent static electrical buildup, thereby eliminating or
reducing the need for antistatic agents.
• Teflon-coated dry cans and guide rollers are widely
used and help reduce fouling, thus avoiding the need
for antisticking agents and toxic machine cleaners.
• Timely movement of goods into wet processing
(desizing) operations eliminates the need for long
shelf life and the use of biocides. Cool, dry storage
conditions suppress mildew and fungus growth and
further minimize the need for biocides.
• Using moisture monitors and implementing advanced
process control reduces or eliminates the need for
deliquescents to protect against overdrying. If de-
liquescents must be used, zinc salts should be avoided.
• The need for size bath stabilizers such as surfactants
or acetic acid can be reduced by maintaining proper
pH control in predyed yarns and ensuring minimal
residual alkalinity in incoming yarns.
• Evaporation barriers on size boxes eliminate surface
skinning and the associated need for deliquescents,
stabilizers, emulsifiers, dispersants, and surfactants.
• Sizing recipes should be based on proper polymer
molecular weights and concentrations to achieve the
proper viscosity, thus eliminating the need for thinning
agents.
• Bar-code tracking can be used to eliminate the need
for tints to visually identify warp beams.
• Proper yarn counts and fabric construction ensure
production of the desired weight fabric, eliminating
the need for weighters.
Organizing production activities as indicated above can
reduce or eliminate the need for additives. This in turn
Clean HgO Out (Recycle To Wash)
Membrane
More Concentrated
Size Mix Out
(Recycle To Size
Mixing Area)
Carbon Support Rod
Figure 4-8. PVA size recovery system.
166
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may iaciVrtate the implementation or operation of size
recovery systems, reduce BOD and aquatic toxicity in
desizing wastewater, and reduce waste from sizing
operations.
4.7.5.4 Raw Material Control in Sizing
QC of incoming raw materials is an important element
of an overall facility pollution prevention strategy. Spe-
cific steps should be taken to minimize the pollution
contribution of sizing and desizing operations.
Incoming warp size (and yarn) should be tested for the
presence of toxic contents, notably zinc and biocides.
Textile mills should seek higher purity, raw size materials
at every opportunity. Mill personnel should perform pre-
screening and shipment checking of size using estab-
lished procedures.
If possible, mills should purchase size in bulk or semi-
bulk IBCs to avoid excessive packaging waste in the
form of bags, pallets, and skids. In addition to generating
wastes, the traditional 80-pound bag is e>xtremely prone
to breakage during transport, storage, and delivery to
the mix kitchen. Improper cleanup of spill from these
packages is a major source of BOD from yarn manufac-
turing and slashing operations. Proper employee train-
ing and resources should be provided to alert
employees to the pollution impacts of improper cleanup.
Proper equipment should be provided for cleaning up
spilled size, including vacuums that can recover the
maximum amount of material. Too often, spilled size is
washed down the drain.
If bags are used, procedures should be established for
handling and storing them in a way that allows for recy-
cling. Methods to avoid container breakage via alternate
packaging, handling, storing, and use as; well as proper
methods of cleaning up spilled size should be an impor-
tant focus for employee training.
4.7.5.5 Monitoring Size and Add-On
Analytical methods are available for determining the size
contents of yarns and fabrics (see the AATCC Technical
Manual [2]). Size add-on should be the minimum re-
quired to achieve the desired results in the subsequent
weaving operation. Size recipes and add-on levels
should be monitored and correlated with production
performance. In many cases, size use can be reduced
without significantly affecting production operations.
Analytical methods are also available for determining
the nominal contents of size mixtures. In addition, sam-
ples from size mixes can be tested for metals. Anything
(including components of the size mixture and impuri-
ties) that is put on the fabric during the slashing opera-
tion will later be removed and become a pollutant.
4.7.5.6 Scheduling
A major source of pollution from slashing operations is
dumping of unused mix. By their nafure, many size
mixes have essentially zero shelf life and cannot be
reused if allowed to sit. Production planning is thus
essential to eliminate mix dumping. Size requirements
should be estimated carefully to avoid mixing of exces-
sive amounts of size. Pipe and pump volume should be
kept to a minimum to avoid waste from the plumbing that
connects the mix kitchen to the size boxes. Therefore,
having the mix kitchen as close to the slasher(s) as
possible is important. Further gains can result from re-
ducing the size of the mix boxes as much as possible.
Finally, the frequency of style and size mix recipe
changes should be minimized to reduce waste from
changeovers. Efforts should be made to use the same
size recipe on as many different styles as possible/then
to group production accordingly.
4.7.5.7 Work Practices
Slashing operations by their nature often appear disor-
derly and sloppy. To significantly reduce the contribution
of slashing to pollutant loads requires training and the
development of proper worker attitudes toward pollution
prevention.
4.7.5.8 Waste Auditing Procedures
Pollution prevention waste auditing procedures that can
be followed include:
• Auditing mix kitchens, slashers, and work areas for
proper chemical handling and work practices (by
methods which are described in a general section on
orderly work practices).
• Focusing on orderly work practices, proper use of
implements, avoiding spills, repairing leaks, proper
cleanup, and correct disposal of chemical residues.
• Accounting for machine cleaning supplies and moni-
toring the required frequency and severity of cleaning
for slasher and mix area components (containers,
utensils, mix tanks, pumps, lines, working area).
• Noting problems with specific size mixtures, fabrics,
or running conditions.
• Counting and monitoring size bags and other size
packing materials (e.g., skids).
• Auditing the incidence of damaged and broken bags,
skids, pallets, and other containers.
• Auditing, measuring, and tracking of dumped, unused
portions of size mixes (a major cause of pollution
from these operations).
• Weighing and monitoring of fiber, lint, and scrap yarn
waste.
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4.7.5.9 Maintenance
4.8.1 Fabric Formation Unit Processes
Equipment maintenance and operations audits are criti-
cal to ensure proper slashing and to minimize fabric
waste and loss of size mix. Avoiding leaks and spills
from size boxes, proper foam suppression, and other
such considerations are essential not only to pollution
prevention but also to proper slasher operation. Mix
kitchen equipment maintenance, including mix tanks,
stirrers, implements, scales, pumps, and piping, is es-
sential. Maintenance, cleaning, and other nonprocess
chemicals should be evaluated for aquatic toxicity.
4.8 Fabric Formation
The following table introduces pollutants and waste
streams discussed in this section, as well as pollution
prevention activities suggested for each.
Pollutant or Waste
Strtam
Pollution Prevention
Actions Described in
This Section
Comments
4.8, Weaving and Knitting (General)
Packaging waste from
yam supply
Yam and fabric scraps
Fabric waste (off-qual-
ity)
Machine lubricants
Latent defects caus-
ing off- quality in later
processing
Standardized, reusable
packaging
Monitoring/auditing;
automated handling
Maintenance of looms
and knitting machines;
optimization of fabric
design and machine
selection
Optimization of use;
evaluation of
alternative lubricants
Automated detectors
for holes and other
defects
CAD systems are
useful in
designing fabrics
for specific
machines
Proper design
reduces the need
for chemical
finishing later
4.8.7, Carpet Formation (Tufting)
Carpet scraps Minimize size for
dyeheader testing and
flammability testing;
minimize
changeover/runout
areas
Yam scraps
Seam cut outs
General fibrous waste
Edge trims
Establish yam waste
goals; monitor/audit
yam waste
Use butt seams, not
lap seams
Train workers to
develop proper
attitudes; establish
goals; assign individual
responsibility
Pay better attention to
width control to reduce
the need for salvage
trimming
Textile fabrics are formed primarily by knitting or weav-
ing processes. A few commercially significant specialty
processes such as nonwoven and braiding exist, but
these are less important than weaving and knitting. One
other important fabric process is carpetmaking, which
forms carpet in several ways, such as weaving and
tufting.
Fabric formation produces relatively little waste com-
pared with other processing steps such as spinning or
finishing. The main waste is the packaging in which yarn
is received, such as cardboard tubes, cases, and cones.
This waste can be reduced by specifying reusable pack-
aging such as shrinkwrap pallets and plastic, reusable
tubes. Fabric formation also produces small quantities
of fibrous materials as waste (e.g., waste yarn, rags, and
fabric scraps). Richardson (46) reported studies of vari-
ous types of fabric in which standardizing yarn package
sizes reduced waste.
Automated handling and inventory systems for yarn and
fabrics are available that provide for automatic weighing
in and out of yarn and fabric, thus accurately tracking
waste. These systems were useful in long-term auditing
of fiber/yarn/fabric waste from fabric manufacturing op-
erations.
4.8.2 Pollution Prevention in Weaving
High-speed weaving machines place great demands on
yarn and size materials. Several alternative types of size
can be used (see Section 4.7, "Slashing and Sizing"),
which differ in their properties, including pollutant poten-
tial. The typical size add-on varies among operations,
so the BOD potential from the desizing operation must
be viewed not only in terms of the BOD (or COD) of the
size material, but also in terms of how much size is
commonly used (47). Although warp size is a major
pollutant in finishing mill wastewater, the needs of the
weaving operation continue to be the main considera-
tion in size selection. An important step toward pollution
prevention in weaving operations is to take a more
global view of size use. Mills need to consider not only
the weaving efficiency of a size but also its pollution
potential in the desizing operation. Upgrading of loom
mechanisms and reduction of speeds may be necessary
to run warps without warp sizes or lubricants (46). This
results in somewhat lower efficiency and production for
the weaver but achieves great savings in pollution at the
slashing and desizing operations (46).
The selection and use of size materials, as noted above,
is crucial. Another consequence of size selection is the
potential for recovery of the warp size in the desizing
operation. Barriers to size recovery include mixing of
sizes by the weaver and geographic separation of the
weaver and the desizer (47).
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A further opportunity for preventing pollution comes
through the use of vacuum extractors rather than ther-
mal evaporation to dry water-jet-woven fabrics. This
saves energy, associated air emissions, and boiler ash
production (46). The recovered water from vacuum ex-
traction can be reused in the size kitchen if the weaving
facility performs sizing on site.
4.8.3 Pollution Prevention in Knitting
Operations
Although knitting operations are generally not consid-
ered a significant pollution source, several aspects of
knitting operations can affect pollution in downstream
operations. These include:
• Fabric quality factors
• Lubricant use, including incoming yarn QC
• Fabric design factors
4.8.4 Fabric Quality Factors
Fabric quality is important in two ways. First, off-quality
fabric (e.g., with holes, dirt, barre) becomes waste at the
end of the process. Beyond this, however, the process-
ing efficiency of knit fabrics at the finishing mill necessi-
tates that incoming fabrics be of high quality. Efficient
rope bleach ranges for knits, for example, consume less
water, energy, and chemicals than batch preparation
methods for knits. But these systems do not function as
well if the knit tube has holes or major defects. The
newer machines feature controlled fabric ballooning and
better fabric transport but are dependent on a well-con-
structed knit tube to operate properly (48). Most knit
guiders used in inspection and finishing operations do
not function properly if the goods contain excessive
holes or major fabric defects.
4.8.5 Lubricant Use
Machine lubricants can contaminate knit goods and be
removed to wastewater during subsequent downstream
processing. Moore reported a study in which BOD and
COD from a knit scouring operation were significantly
reduced by controlling the quality and contents of the
incoming yarn and lubrication of the knitting machines
in the knitting operation (36). The incoming knitting yarn
was screened by standard test methods for extractable
content. In addition, the amount of knitting oil used for
the knitting machines was controlled (36). These pollu-
tion prevention steps brought the mill's scouring system
into compliance without costly waste treatment system
construction.
4.8.6 Fabric Design Factors
The importance of properly considering product pro-
perties at the design and raw material selection stage
is emphasized in Section 3.2, "Design-Stage Planning
for Facilities, Processes, and Products." Computer-
aided technical (in addition to aesthetic) design of knit
fabrics can ensure correct yield and shrinkage of knit
goods, thus reducing or eliminating the need for chemi-
cal finishing. Proper yarn selection and careful process-
ing can ensure proper weight, width, shrinkage, and
spirality of the final product without chemical finishes.
Yarn selection and knitting machine setup, as well as
essentially tensionless handling of fabric, are crucial to
ensuring that fabric ultimately achieves its relaxed equi-
librium configuration. A final configuration that meets cus-
tomer specifications eliminates the need for chemical
finishes (49).
Often, textile mills achieve the above design criteria but
fail to implement the necessary measures in the knitting
room. Important considerations include proper schedul-
ing and setup of knitting machines for each style. Most
often, problems arise when production demand exceeds
the capacity of the machine group best suited for the
particular style. Compromises are often made with the
decision to knit on alternate machines, accepting the
probability that chemical resins (with formaldehyde) will
be necessary to stabilize the fabric at the customer's
specifications.
4.8.7 Pollution Prevention in Carpetmaking
Carpet formation also deserves attention in terms of
pollution prevention. Carpet waste amounts to 2 percent
of the total annual production of 900 million square
yards, or 18 million square yards of waste per year (50).
The dollar value of this waste is about $100 million. One
carpet manufacturing operation that produced about 8
million yards of carpet annually had more than $500,000
in waste per year, as shown in Table 4-33 (50).
A careful cost analysis of a typical carpet operation
shows that reducing waste by 2 percent would increase
pretax profits by 26 percent (50). Pollution prevention
activities that were implemented in carpet manufactur-
ing include the following:
Table 4-33. Amounts and Value of Waste in Carpet
Manufacturing (8 Million Square Yards per Year
Facility) (50)
Type of Waste
Annual Value ($)
Backing selvage
Mitter selvage
Backing seams
Seam trim
Other trim, selvage, and samples
Miscellaneous
Total
96,000
92,000
71,000
53,000
190,000
10,000
512,000
169
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• Tufting dyeheader samples (i.e., yarn QC check)
are typically a yard or more. Carpetmaking opera-
tions cut 1,175 of these each year. This can be re-
duced to 8 inches for a savings of 80 percent, or
$23,000 per year.
• Tufting yarn changeovers (e.g., merge, pattern, type)
occur by "runout," which can be minimized as shown
in Figure 4-9. By reducing runout to minimum dis-
tance, the average savings were 25.3 inches of car-
pet. At a frequency of 300 times per year, the value
was $41,000.
• Failure to adhere to established yarn waste stand-
ards accounted for 1,200 pounds annually of excess
waste yam, with a value of $14,000.
• Converting from lap to butt seams in carpets reduced
seam waste by 50 percent (see Figure 4-10), thereby
saving $70,000.
• Better worker training and attention to cutting, espe-
cially in producing straight cuts, reduces trimming
before seaming. Average savings were over 4 inches
per seam, or $17,000 per year.
• Minimizing trim saved $5,000 annually.
• Minimizing test samples can also reduce waste. For
example, flammability tests require 12- x 12-inch
samples. Cutting oversized samples (i.e., 17- x 17-
inch), plus other oversized samples for testing,
wasted $12,000 of material.
• Better training and attention to width control in tufting
and printing saved an average 3.4 inches on all car-
pets produced, for an annual savings of $91,000 in
one operation. In another, excessive selvage trim
was reduced 3.23 inches, resulting in an annual sav-
ings of $228,000.
Palmer reported that the key pollution prevention steps
In carpet operations include (50):
The broken lines represent typical cut marks, and the
area between the broken and solid lines represents
wasta that can be avoided.
Figure 4-9. Potential waste savings from reducing runout from
dye samples (50).
Lap Seam
Cutting
points
Butt Seam
4"
Cutting
points
Converting to butt seams reduces waste by 50 percent. Total waste
per lap seam is 8 inches; the total per butt seam is 4 inches.
Figure 4-10. Potential waste savings in converting to butt
seams from lap seams in carpet (50).
• Selecting one person with technical qualifications and
authority to coordinate all pollution prevention activities.
• Establishing goals from sources such as literature,
other mills, and trade associations.
• Studying waste reduction opportunities.
• Reporting waste quickly in an understandable way
and highlighting expectations.
4.9 Preparation
The following table introduces the pollutants and waste
streams discussed in this section, as well as suggested
pollution prevention activities for each.
Pollutant or Waste
Stream
Pollution Prevention
Actions Described
in This Section Comments
4.9, Fabric Preparation
Water
Alkalinity
BOD and COD
Metals and other tox-
ics
Surfactants (aquatic
toxicity)
Reuse and
countercurrent use;
flow optimization
Recycle/recovery
(sometimes possible)
Testing incoming
greige goods
Testing incoming
goods for
contaminants
Selecting degradable
types; avoiding
cationics
Continuous
processes lend
themselves better
to recycle/reuse
Global approach to
additives is
important
170
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GervexaV
Desizing pollutants
Right-first-time
production; optimized
processes; good
process and product
QC; automated
process controls,
such as titrators and
chemical feed
systems
See Section 4.7 table
above
Latent defects are
often not observed
until problems
arise in later
processes
Most cloth routinely undergoes one or more finishing
processes after it emerges from the manufacturing proc-
ess. These include:
• Cleaning the cloth before finishing
• Improving texture and hand
• Colorization (specifically, dyeing and printing)
• Inspection and QC
This section deals with fabric preparation, the first two
steps in the above finishing sequence.
Most fabric that is dyed, printed, or finished must first be
prepared, with the exception of denim and certain yard-
dyed knit styles. Because preparation is a universal
process, and techniques are relatively uniform across
most of a mill's production, preparation is usually the
highest volume single process in a mill and hence an
important area for pollution prevention.
In preparation, the mill removes contaminants that inter-
fere with dyeing, printing, and finishing (20). If fabrics
contained no contamination upon arrival for wet proc-
essing, preparation processes would be unnecessary.
About half of all the pollution and a significant amount
of the wastewater from textile wet processing could be
prevented (20). The main pollutants from preparation
are water, alkalinity, BOD, COD, and small amounts of
offensive materials such as metals and surfactants (11,
27).
Preparation is crucial to every subsequent process in
the textile mill, but it is underrecognized as a source of
quality and pollution problems. Preparation often re-
ceives little attention from managers and technicians,
who are concerned with "more important" problems
such as bad dyeing, printing, and finishing work (which
themselves are caused by poor preparation). Because
visually observing poor preparation when it occurs can
be difficult, poorly prepared work generally goes unno-
ticed and is subject to further processing, which inevita-
bly reveals latent defects in preparation. This results in
more costly finishing and dyeing reworks, off-quality
production runs, excess pollution, and other problems
(51). In effect, the preparation process sets; an upper limit
on quality that cannot be improved in later processes.
One key to pollution prevention is right-f/rst-f/me produc-
tion, and the key to right-first-time production is com-
plete, consistent preparation. In an attempt to ensure
right-first-time production, many standard quality evalu-
ation tests for prepared fabric have been developed, as
well as process tests to control preparation parameters
(e.g., concentration of caustic, peroxide). Automated
control systems also are available to monitor prepara-
tion variables. These include automatic titrators, chemi-
cal feed control systems, and other such systems.
Any pollution prevention program, especially one aimed
at water conservation, would benefit from a thorough
audit of preparation procedures, and a study of state-of-
the-art preparation equipment appropriate to the cloth
styles being produced. This section discusses sources
of pollution from textile preparation and identifies rele-
vant pollution prevention strategies.
4.9.1 Preparation Processes
Greige goods must undergo a series of preliminary
cleaning treatments before the finishing mill applies any
functional finishes or before they move on to dyeing and
printing. These preliminary treatments include desizing,
scouring, bleaching, and singeing. Following cleaning
and scouring, most cloth is in a relaxed condition and
must be straightened and brought to its proper configu-
ration before it undergoes further finishing steps. This is
particularly important for finishes meant to impart sur-
face design or color. Also, treating cloth to make it more
stable or chemically reactive is advantageous because it
makes subsequent chemical finishes more permanent.
These processes include heatsetting and mercerizing.
4.9.1.1 Continuous Versus Batch Preparation
Processes
Most mills can use uniform preparation processes for
the entire range of products they produce. Economics,
as well as pollution control, thus favor continuous rather
than batch preparation processes (52). Although con-
tinuous preparation is more common, quite a few mills
still prepare goods (especially knits) batchwise on dye-
ing machines. The usual justification for not preparing
goods continuously is complexities in scheduling, han-
dling, and other factors. Some of these other factors
include the high capital cost and the capacity required
for high productivity of knit preparation equipment. Low-
volume knit operations often cannot justify the cost of
this equipment given the volume of material they have
to process. In addition, continuous preparation and dye-
ing schedules must be coordinated to ensure that goods
do not sit around wet for a long time. If knit goods must
be dried for storage, the economic loss is great because
of the high cost of drying. Finally, storing and tracking
goods through continuous preparation and dyeing is
more complicated than simply loading goods into one
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machine and doing both processes sequentially on the
same machine.
Mills using batch preparation may find that pollution
prevention considerations provide sufficient incentive to
consider switching to continuous preparation and/or fin-
ishing. Unlike batch processes, continuous operations
provide greater segregation for recycle and reuse of
waste streams.
4.9.1.2 Desizing
Sizing materials are applied to warp yarns before they
are woven into cloth. The sizing materials form a protec-
tive coating over the yarns and prevent chafing or break-
age during weaving. Chemicals used as sizing agents
may be divided into two categories: 1) water-soluble
sizes, such as PVA and 2) water-insoluble sizes, such
as starch. Oils, waxes, and other additives are often
used in conjunction with sizing agents to increase the
softness and pliability of the yarns (see Section 4.7,
"Slashing and Sizing").
Manmade fibers are generally sized with water-soluble
sizes that are easily removed by a hot-water wash or in
the scouring process. On the other hand, natural fibers
such as cotton are most often sized with water-insoluble
starches or mixtures of starch and other size materials.
Enzymes are used to break these starches into water-
soluble sugars, which are then removed by washing
before the cloth is scoured. Removing starches before
scouring is necessary because they can react and
cause color changes when exposed to sodium hydrox-
ide (alkali) in scouring.
Bacteria in waste treatment can easily attack water-sol-
uble sugars, which are the by-product of desizing.
Water-soluble sugars are very degradable and have a
high BOD. As a result, desizing of starch-sized fabrics
often accounts for more BOD than all other processes
In the finishing mill combined (11).
Many of the pollution concerns associated with sizes are
discussed in Section 4.7, "Slashing and Sizing." To pre-
vent pollution in desizing, the least-polluting alternative
is to use, then recover and recycle, synthetic sizes. A
prerequisite for this is that the weaver and the finisher
must be in close geographic proximity.
In addition to geographic considerations, the weaver
and the finisher must have a joint interest in pollution
prevention. This is because the recovered size does not
directly benefit the finisher, or vice versa. Therefore, a
more global pollution prevention strategy or perspective
must be developed to facilitate size recovery and reuse.
Vertically integrated operations, where the weaving and
finishing occur within the same organization, greatly
facilitate this strategy. Nevertheless, not all integrated
operations that are able to take advantage of size recov-
ery do so. One reason for this is that size recovery
equipment is expensive and only economically feasible
in high-volume operations. On the other hand, some
weavers and finishers, not connected through the cor-
porate chain, cooperate to use and recover synthetic size.
4.9.1.3 Scouring
Scouring is a cleaning process that removes impurities
from fibers, yarns, or cloth. The impurities include lubri-
cants, dirt and other natural materials, water-soluble
sizes, antistatic agents, and fugitive tints used for yarn
identification.
Scouring uses alkali to saponify natural oils, and surfac-
tants to emulsify and suspend nonsaponifiable impurities
in the scouring bath. The specific scouring procedures,
chemicals, temperature, and time vary with the type of
fiber, yarn, and cloth construction. Two main pollution
prevention principles must be addressed for scouring:
• Incoming greige goods may contain contaminants
and should undergo testing and QC (see Section 4.2,
"Fiber")- Any goods containing toxic or offensive con-
taminants (e.g., pentachlorophenol on wool, metals
on cotton, toxic spin finishes on synthetic) should be
rejected because subsequent wet processing re-
leases these pollutants into the wastewater or air.
• Surfactants used in desizing should be easily degrad-
able. These types of surfactants can be identified by
their low COD:BOD ratios and high BOD values. See
Sections 2.2.5, "Metals," and 4.4, "Chemical Specialties."
4.9.1.4 Bleaching
Bleaching is a chemical process that eliminates un-
wanted colored matter from fibers, yarns, or cloth.
Bleaching decolorizes colored impurities that are not
removed by scouring and prepares the cloth for further
finishing processes such as dyeing or printing.
Several different types of chemicals are used as bleach-
ing agents, and selection depends on the type of fiber
present in the yarn, cloth, or finished product and the
subsequent finishing that the product will receive. The
most common bleaching agents include hydrogen per-
oxide, sodium hypochlorite, sodium chlorite, and sulfur
dioxide gas. Hydrogen peroxide is by far the most com-
monly used bleaching agent for cotton and cotton
blends, accounting for over 90 percent of the bleaching
agents used in textile operations. Peroxide is an envi-
ronmentally benign chemical because it is easily treat-
able and decomposes into water and oxygen during
treatment.
The bleaching process involves several steps:
1. The cloth is saturated with the bleaching agent, ac-
tivator, stabilizer, and other necessary chemicals.
172
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2. The temperature is raised to the recommended level
for that particular fiber or blend and held for the amount
of time needed to complete the bleaching action.
3. The cloth is thoroughly washed and dried.
The bleaching agent, temperature, and processing time
must be carefully controlled to avoid damage to the fiber,
or severe losses in strength may occur.
Pollution from bleaching stages normally is not a major
concern. In most cases, scouring has removed impuri-
ties in the goods, so the only by-product of the peroxide
reaction is water. Aside from chemical handling issues
and water conservation (covered in other sections), little
effort is required to reduce pollution from bleaching. Of
course, maintaining high efficiency and quality ensures
right-first-time production and reduces reworks in later
processes.
4.9.1.5 Singeing
Singeing is a dry process used on woven goods that
removes fibers protruding from yarns or fabrics. These
are burned off by passing the fibers over a flame or
heated copper plates. Singeing improves the surface
appearance of woven goods and reduces pilling. It is
especially useful for fabrics that are to be printed or
where a smooth finish is desired. Singeing has essen-
tially no pollutants associated with it other than small
amounts of exhaust gases from the burners.
4.9.1.6 Mercerizing
Mercerization is a chemical process for cotton and cot-
ton/polyester goods that increases their dyeability and
luster, and improves appearance. The yarn or cloth is
treated under tension at room temperature with a 20-
percent caustic solution. After treatment, the caustic is
removed by several washes, also under tension. Re-
maining alkali may be neutralized with a cold acid treat-
ment followed by several more rinses to remove the acid.
Mercerizing can generate substantial amounts of high
pH alkali (about 20 percent owg). This waste stream can
be recycled through evaporative caustic reclamation
systems, but this is rarely practiced because the sys-
tems are expensive and require a large volume to justify
the capital cost. Another reuse opportunity is to recycle
the alkali into the scouring process.
4.9.1.7 Heatsetting
Heatsetting is a dry process used to stabilize fabrics with
a high content of synthetic polymers. When manmade
fibers are heatset, the cloth maintains its shape and size
in subsequent finishing operations, as long as it does
not encounter temperatures higher than the setting tem-
perature. The cloth is stabilized, or set, in the form in
which it is held during heatsetting (e.g., smooth, creased,
uneven). Thus, heatsetting is widely used to impart a
variety of textural properties to manmade fibers. These
properties include interesting and durable surface ef-
fects such as pleating, creasing, puckering, and em-
bossing. Heatsetting also gives cloth resistance to
wrinkling during wear and ease-of-care properties attrib-
uted to improvements in resiliency and in elasticity.
In the manufacture of synthetic fibers, proprietary spin
finishes often are used to provide fiber lubrication and
other desirable properties, such as static electricity con-
trol (20). These spin finishing agents contain volatile
components that are vaporized during heatsetting (20).
Several pollution prevention strategies can help avoid this:
• From 50 to 80 percent of the air in gas-fired heatset-
ting frames can be recirculated, thereby burning up
contaminants as they pass through the gas flames.
This of course does not work on steam tenters. This
strategy is best implemented by real-time monitoring
of humidity in the heatset area and appropriate
damper control.
• Improved or more aggressive scouring may remove
these finishes from the goods before heatsetting. This
may trade an air pollution problem for a water pollu-
tion problem, however, because the spin finishes will
be removed with wastewater from scouring opera-
tions. Wastewater treatment, however, may be capa-
ble of degrading these pollutants to some degree to
reduce their impact, whereas volatilization releases
them entirely to the atmosphere (see Section 4.2,
"Fibers").
• Heatsetting should be done after dyeing (not in
greige). After dyeing, the spin finish is removed from
the air and transferred into water where it can be
more easily treated.
• Incoming synthetic goods (or fiber, if possible) should
be monitored for spin finish add-on levels and chemi-
cal makeup. The quantitative amount of spin finish in
fiber can be easily monitored by extracting the finish
from the fiber. The chemical content can be deter-
mined by analyzing the extract by infrared or any of
several chromatographic methods (e.g., GC, HPLC).
Mills should follow up on this analysis by developing
a fiber purchasing specification based on the moni-
toring results.
4.9.2 Summary of Pollution Prevention
Strategies for Preparation Pollutants
Preparation is essential to obtaining good results in
subsequent textile finishing processes. Many of the pol-
lutants from preparation result from removal of pre-
viously applied contaminants and upstream processing
residues, and these can be passed on to subsequent
stages if preparation is poor. QC of incoming raw mate-
rials (including substrate, fiber, yarn, and fabric) is thus
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one of the most crucial elements of a pollution preven-
tion strategy. QC must include testing for offensive or
hazardous materials.
The sections below identify important pollution preven-
tion considerations for the main categories of pollution
found in preparation.
4.9.2.1 Water Reduction in Preparation
Preparation procedures should be thoroughly audited
for chemical use and handling, equipment condition,
and in-process quality verification. Mills should study
and evaluate the state-of-the-art preparation equipment
appropriate to the styles they are producing. Water
conservation is covered in detail in Section 2.2.7, "Water
Conservation."
4.9.2.2 Alkalinity
Preparation processes generally are carried out in a
range of pH conditions: from neutral to highly alkaline
conditions. As a result, the pH of preparation wastewater
is frequently above 11. NPDES and POTW pretreatment
regulations generally require an upper pH limit of 9 or
10; thus, alkaline waste streams from preparation
should be reused wherever possible. A typical scheme
is shown in Figure 4-11 (53). In general, and especially
for cotton, no substitutions are available for alkalinity in
scouring and bleaching, so the high pH cannot be elimi-
nated by any process alternative.
4.9.2.3 Biological Oxygen Demand
Most of the BOD in textile preparation comes from sizes,
knitting oils, and natural impurities that are removed
from the greige fabrics. Table 4-34 (11) shows typical
BOD levels from preparation processes.
Because most BOD from preparation comes from up-
stream residues (e.g., knitting oils), little can be done in
the preparation process itself to reduce BOD. Although
mills are often tempted to use surfactants with low BODs
to reduce pollution load and associated POTW sur-
charges, they must do so with great caution to avoid
introducing processing materials that pass through
waste treatment systems and cause aquatic toxicity in
the effluent or sludges. This is discussed further below
and also in Sections 2.2.6, "Aquatic Toxicity," and 4.4,
"Chemical Specialties." The best pollution prevention
strategy for BOD is to use, recover, and reuse synthetic
sizes. This can reduce BOD as well as dissolved or
suspended solids in effluent.
4.9.2.4 Aquatic Toxicity
Surfactants, which cause much of the aquatic toxicity
from textile operations, are a minor source of offensive
wastes produced during preparation. AP surfactants are
not completely degradable in typical waste treatment
Table 4-34. BOD From Preparation Processes (11)
Process
Pounds of BOD per 1,000
Pounds of Production
Singeing
Desizing starch
Desizing starch mixed size
Desizing PVA or CMC
Scouring
Bleaching with peroxide
Bleaching with hypochlorite
Mercerizing
Heatsetting
0
67
20
0
40-50
3-4
8
15
0
Caustic
Washer
Recycle
Drain to
Desize Mix
Reuse Wash
Water for
Desize Washer
Fabric to
Bleach
Unit
Wash Water
From Bleach
Washer
Figure 4-11. Reuse of alkaline waste streams from desizing and scouring operations (53).
174
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systems, and even if degraded, the degradation resi-
dues are phenols, which are toxic to fish (22, 23). Other
types of surfactants, such as LAE, are less toxic (22,
23). Degradable surfactants should be favored over
nondegradable ones despite their extremely high
BOD values.
When purchasing commodity surfactants, mills can
easily assess the surfactants' aquatic toxicity potential.
If the surfactant is part of a proprietary compounded
specialty, however, the responsibility for assessing tox-
icity rests with the formulator (22, 23). In practice, mills
often have difficulty obtaining toxicity information for
proprietary chemicals.
The toxicity of surfactants is discussed in Sections 2.2.6,
"Aquatic Toxicity," and 4.4, "Chemical Specialties," as are
the difficulties of obtaining information concerning envi-
ronmental impacts of surfactants and other specialties.
4.9.2.5 Metals
Metals originate in the incoming fabrics. The types and
amounts of metals found in textile fibers and fabrics are
covered in detail in Section 2.2.5, "Metals." To reduce
the potential for releasing metals to wastewater during
preparation, mills should test and monitor incoming
greige goods as part of their QC and pollution prevention
program.
4.9.3 Pollution Prevention Through
Equipment Selection and Use
Several types of scouring/bleaching equipment or
equipment modifications are available that can reduce
or minimize pollution from preparation operations.
These include:
• Countercurrent washing
• Low-bath-ratio batch bleaching with bath reuse built in
• Continuous horizontal washers
• Continuous knit bleaching ranges
• Combined single-stage processing
4.9.3.1 Countercurrent Washing
Countercurrent washing equipment can be retrofitted to
any multistage continuous washing operation, whether
it is installed for dyeing, printing, or in this case, prepa-
ration. Continuous preparation ranges run the fabric
through three consecutive stages that progressively
clean the fabric: desizing, scouring, and bleaching. Each
stage comprises a process bath, a dwell time, and a
washing step. As the fabric progresses through the three
steps, various impurities are removed. Because of this,
the washwater from the final stages contains few impu-
rities and can be reused as feed for previous processing
stages instead of being dumped from washers. Figure
4-10 depicts a Countercurrent washing setup (53).
Countercurrent washing equipment is applicable to a
variety of operations and fabrics. It is common in modern
mills and is becoming more common in older mills as
these mills upgrade and update their equipment. Al-
though Countercurrent washing equipment has low op-
erating costs and offers pollution and energy savings, it
has a fairly high capital cost. This may make some mills
slow to change to this equipment.
Often, water flows in washing are excessive. Flow opti-
mization makes a good companion activity to the instal-
lation of Countercurrent washing.
4.9.3.2 Low-Bath-Ratio Kier Bleaching Systems
Low-bath-ratio kier bleaching systems reduce wastewa-
ter volume. A typical example of such equipment is the
Scholl AG BLEACHSTAR ultra-low-liquor bleach range
(54), designed for a wide range of knit fabrics. The
machine features holding tanks for storage of scouring
and bleach baths. These counterflow tank systems fa-
cilitate easier bath reuse (54). The washwater from the
previous load is recovered and then fully used in the
bleach bath for the current load, which can then be used
to scour the next load. In this way, each bath is used
three times and the ultimate water use is only about 0.8
gallons of water per pound of cloth from an average of
4.5 to 6.0 gallons (54).
4.9.3.3 Continuous Horizontal Washers
Continuous horizontal washers can conserve energy,
and water. The process, as shown in Figure 4-12, is to
spray clean washwater on the top (final) pass of fabric
as it makes a series of horizontal traverses upward in
the machine (13). The unprocessed fabric enters at the
Sprays
Fabric
Entry
Figure 4-12. Horizontal washer configuration (13).
175
-------
bottom traverse, and the water enters at the top. These
vertical spray washers reduce water and energy use as
well as improve quality and captured suspended solids
for dry disposal.
4.9.3.4 Continuous Knit Bleaching Ranges
Many textile companies use continuous knit bleaching
ranges, which have significant pollution prevention ad-
vantages, one of which is water conservation (11). Until
the early 1980s, continuous knit preparation machinery
was limited in the styles that it could run. Many knit
styles exhibited rope marks, crows feet, creases, and
cracks if continuously prepared. That changed with the
introduction of efficient rope bleach ranges for knits,
based on Jet-dyeing principles. These ranges consume
less water, energy, and chemicals than batch prepara-
tion methods for knits (48).
More recent models of continuous knit ranges have
been improved mechanically as well as in flexibility of
production capacity. A significant change was the intro-
duction of lower capacity machines for smaller opera-
tions (48). Previous models were so large that small
operations (those processing under 100,000 pounds per
week) could not justify them economically. The new
machines also feature inherent countercurrent water
use, reduced ballooning of the fabric, better fabric trans-
port, better chemical metering systems, fabric sensors
to ensure proper dwell time, better filtering of the baths,
and better controls (49).
4.9.3.5 Combined Single-Stage Processing
Combining scouring and bleaching also can save en-
ergy and water. In addition, a cold pad-batch method
can be used at room temperature for long desizing,
scouring, and bleaching cycles (12 hours overnight).
The single-step, cold-batch method of desizing mini-
mizes energy and water use and maximizes productivity
in desizing (47). Bleaching and scouring are combined,
and all preparation is carried out in the single-step,
cold-batch process (47). Recipes for desizing are given
in Table 4-35 (47). The composition of most proprietary
stabilizers can be estimated. Figure 4-13 compares the
performance of the three desizing methods on various
types of sizes (47).
4.10 Dyeing
The following table introduces the pollutants and waste
streams discussed in this section, as well as suggested
pollution prevention activities for each.
Pollutant or Waste
Stream
Pollution Prevention
Actions Described
in This Section
Comments
4.10, Dyeing
Toxicity: metals, salt,
surfactants, organic
processing assistants,
cationic materials
Air emissions: VOCs
Color
BOD and COD
Sulfide
General: acidity/alka-
linity, water
Special experimental
techniques for gen-
eral application
Process alternatives,
modification, and
optimization; optimum
auxiliary selection
and use; substitution
of mechanical for
chemical process
facilitation; machine
cleaning and
scheduling
Chemical selection
Work practices;
maximized
exhaustion and
fixation
Chemical substitution;
substitution of
mechanical for
chemical process
facilitation
Chemical alternatives
Equipment selection
(low bath ratio);
optimized and well-
controlled processes
for maximum right-
first-time production;
avoidance of mix
discards; use of
automated chemical
dispensing; training;
maintenance;
minimized chemical
specialty use
Dyebath reuse;
experimental
techniques (e.g.,
waterless SCF
dyeing and
ultrasonics)
See Sections 2.2.3
and 4.4
Fiber reactive dyes
are the primary
problem area
Applies to sulfur
dyes
This section describes opportunities for furthering pollu-
tion prevention efforts in textile and finishing mills
through dyeing process specification, dyeing equipment
selection and operation, and other work practices re-
lated to textile dyeing.
Some dyers may have less latitude than other types of
textile processors in specifying less polluting dyeing
processes, because much dyeing is done by commis-
sion dyehouses according to the customer's specifica-
tions. Persuading customers of the need to modify the
product may be difficult in this case because no imme-
diate benefits will accrue to them. Textile product manu-
facturers, however, are increasingly interested in the
"life-cycle" environmental impacts of their products and
are seeking ways to reduce this impact. Information in
this section will help the commission dyer appeal to the
customer's desire for products with reduced life-cycle
176
-------
0
a. Size removal (%) by low-level
hydrogen peroxide.
F. G
b. Consumption (%) of hydrogen
peroxide—size removal by
low-level hydrogen peroxide.
0-
B
c. Size removal (%) by high-level
hydrogen peroxide, low pick-up.
0
d. Hydrogen peroxide consumption
(%)—size removal by high-level
hydrogen peroxide at low pick-up.
e. Size removal (%) by high-level
hydrogen peroxide at high pickup.
A B C D E F G
f. Hydrogen peroxide consumption
(%)—size removal by high-level
hydrogen peroxide at high pickup
Figure 4-13. Comparison of three alternative desizing methods on different types of size. A= natural starch; B = modified starch-
C = CMC; D = PVOH (low viscoiiity); E = PVOH (medium viscosity); F = acrylic; G = PES (47). '
177
-------
Tablo 4-35. Alternative Recipes for Deslzlng Processing
Baths (47)
Roclpo Details
Add-On Level
Recipe 1: Low-level hydrogen peroxide with low pickup
Hydrogen peroxide 35% 45 g/kg
Caustic soda 100% 20 g/kg
Stabilizer X 12 g/kg
Leontl EB'L-X 15 g/L
(65% pickup)
Recipe 2: High-level hydrogen peroxide with low pickup
Hydrogen peroxide 35% 60 g/kg
Caustic soda 100% 20 g/kg
Stabilizer 82-X 15 g/kg
Leonil EBL-X 15 g/L
(65% pickup)
Recipe 3: High-level hydrogen peroxide with high pickup,
using a special stabilizer
Hydrogen peroxide 35% 60 g/kg
Caustic soda 100% 20 g/kg
Stabilizer 82-X 15 g/kg
Leon!! EBL-X 15 g/L
(100% pickup)
impacts, and foster an awareness of these impacts
among all customers. This is discussed further in Sec-
tion 4.17, "Globalization of Pollution Prevention."
For dyers working in vertical operations, the benefits of
pollution prevention accrue to the organization as a
whole. This section assists the dyer in identifying the
benefits associated with pollution prevention, including:
• Reduced dye and chemical costs
• Reduced water consumption
• Reduced energy consumption
• Improved product quality
• Improved process reliability
4.10.1 Introduction to Dyeing Processes
Modern textile dyeing is a complex operation that re-
quires the dyer to be knowledgeable in many different
areas: fibers and their physical and chemical properties,
dye chemistry and dye application techniques, construc-
tion methods used for yams and fabrics, and many
fastness, quality control, and economic considerations
for the finished product. The fundamentals of dyeing
practice, however, are relatively straightforward. Textiles
may be dyed during any of four stages of production,
using either batch or continuous techniques. The stage
of production chosen for dye application and the type of
process selected depend on the desired results, the
relative costs of different dyeing methods, available ma-
terials, demand considerations, and other factors.
4.10.1.1 Dyeing at Various Stages of Production
Textiles may be dyed in fiber form (before spinning), as
spun yarns (after the finished material has been woven
or knit), or, in the case of apparel, in garment form after
cutting and sewing.
Fiber Dyeing
Fibers may be dyed before they are spun into yarns or
woven or knit into textile fabrics. In stock dyeing, the raw
fiber is dyed in large kiers. Irregularities in shading are
overcome when the fibers are blended into yarn. In top
dyeing, fibers are shaped into lightly twisted ravings, or
tops, before dyeing. Uniform colors are attained in both
dyeing methods.
Yam Dyeing
Textiles may be dyed in yarn form before they are used
to weave or knit a pattern or design into the cloth. The
three methods for batch dyeing yarn are skein dyeing,
package dyeing, and beam dyeing.
Skein dyeing is used for large, bulky, or delicate yarns.
The yarn is formed into loose coils, called hanks or
skeins, which are then immersed in a large, open dye-
bath. Dye penetration is good because the yarn is dis-
tributed loosely in the bath.
In package dyeing, yarns are wound onto perforated
tubes or springs, stacked on perforated rods, and placed
in a pressurized tank. Dye is pumped through the rods
and ultimately through the yarn package. The liquid is
recirculated until the proper color is achieved. Package
dyeing is somewhat quicker than skein dyeing because
it forces the dye through the yarn under pressure. Pack-
age dyeing is preferred for dense, small, highly twisted
yarns, whereas skein dyeing is preferred for large,
loose, bulky yarns, especially wool and acrylic.
The beam dyeing process is similar to the package
dyeing process except that yarns are wound on a per-
forated warp beam. The advantage of beam dyeing is
that following drying, the beams can be moved directly
to slashing and then onto the loom, when they are
needed for weaving. Yarns can also be continuously
dyed either on a slasher or on a continuous range, using
a technique known as chain dyeing.
Cloth or Piece Dyeing
Piece dyeing involves the dyeing of woven or knit cloth
and may be accomplished by batch or continuous proc-
esses. The choice between batch and continuous dyeing
usually depends on such factors as fabric construction,
cost considerations, the dye classes chosen (and
their applicability to batch or continuous equipment), the
minimum lot size required for economical running, and
the availability of equipment. Generally, except for dye
jobs involving less than 1,000 meters of cloth, most
178
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woven material is dyed by continuous processes. Most
knit cloth, on the other hand, is dyed by batch methods
because it cannot withstand the tension of the continu-
ous range.
4.10.1.2 Batch Versus Continuous Dyeing
In continuous dyeing, textile materials are fed continu-
ously into a dye range at speeds of roughly 50 to 250
yards per minute. For any color, continuous dyeing is
less expensive, has lower labor requirements, and gen-
erates less waste for long runs of 10,000 yards of more.
Continuous dyeing processes usually consist of dye
application, dye fixation with chemicals or heat, and
washing.
For short runs, batch dyeing is generally more economi-
cal because of the higher startup arid stopoff costs
associated with continuous dyeing. In batch dyeing, a
given amount of textile material is loaded into a dyeing
machine and brought to equilibrium, or near equilibrium,
with a dye-containing solution. The dyes have affinity for
the fibers, which causes the dye to leave the dye solu-
tion and enter the fibers over a period of minutes to
hours. Use of chemicals and controlled temperatures
accelerate and optimize the exhaustion of the dye. Dye
is then fixed in the fiber using heat and/or chemicals,
and the textile material is washed.
A third type of dyeing, known sometimes as semicon-
tinuous dyeing, applies dyes continuously but fixes and
washes the material batchwise. Pad-batch dyeing, the
best known semicontinuous process, is described later
in this section.
4.10.1.3 Rope Versus Open-Width Dyeing
Dyeing machines can be classified into two types: rope
and open width. With rope dyeing machines, the fabric
is transported through the machine in a loosely col-
lapsed form resembling a rope. In open-width dyeing,
the fabric is maintained in a flat and open condition at
all times. The main fabric dyeing machines are classified
as follows:
Machine
Beam
Beck
Continuous
Jig
Jet
Pad-batch
Configuration
Open
Rope
Open
Open
Rope
Open
The most popular rope dyeing machines are jets, fol-
lowed by becks. The most popular open-width dyeing
machines are beams, followed by jigs and pad-batch.
The choice of rope versus open-width dyeing depends
on the fabric's ability to withstand the mechanical de-
mands involved in the two methods. Rope dyeing has
the potential for abrasion of fabrics as well as permanent
creases, cracks, and streaks. Open-width dyeing ap-
plies tension to fabrics and thus has the potential to form
edge marks and creases in tubular knit goods. Jet dye-
ing machines (for rope dyeing) have been engineered
to be more gentle and can handle most styles of goods.
Thus, jets have emerged in the United States as the
dominant batchwise piece dyeing machines (see Figure
4-14).
Dye Liquor Is Pumped, Thus
Transporting Fabric Through
the Dyeing Venturi Tube
Venturi Tube
Dye Liquor
Jet Dyeing
Figure 4-14. Schematic of jet dyeing machine.
4.10.2 Pollutants Associated With Dyeing
Many pollutants are associated with the dyes and
chemicals used in dyeing processes. These may origi-
nate from the dyes themselves (e.g., toxicity, metals,
color) or derive from auxiliary chemicals used during the
dyeing process (e.g., salt, surfactant, levellers, lubri-
cants, alkalinity). Pollutant impacts are also associated
with chemicals used during dyeing equipment mainte-
nance and cleaning.
Dyeing contributes most of the metals and essentially
all of the salt and color in effluent from textiles opera-
tions, and these are priority areas for pollution preven-
tion. Wagner (14) reports that dyeing consumes 8
percent of the water and contributes 5 percent of the
BOD in a typical cotton finishing operation.
Some common aquatic pollutants associated with dye-
ing processes are presented in Tables 4-36 and 4-37.
Table 4-36 outlines the types of pollutants associated
with dyes of various types, while Table 4-37 shows the
BOD contribution to waste of various auxiliary chemicals
associated with each of the major dye classes.
179
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Tabla 4-36. Types of Pollutants Associated With Various
Dyes (55)
Class
Direct dyes
Reactive dyes
Vat dyes
Sulphur dyes
Chrome dyes
1:2 Metal
complex dyes
Acid dyes
Disperse dyes
Fiber
Cotton
Cotton
Cotton
Cotton
Wool
Wool
Wool
Polyester
Type of Pollution
Salt
Unfixed dye
Copper salts
Cationic fixing agents
Salt
Alkali
Unfixed dye
Alkali
Oxidizing agents
Reducing agents
Alkali
Oxidizing agent
Reducing agents
Unfixed dye
Organic acids
Unfixed dye
Metals
Sulfide
Organic acids
Metals
Organic acids
Unfixed dyes
Reducing agents
Organic acids
Carriers
Dyeing also contributes to air emissions. Many volatile
chemicals are used in dyeing, and these are reviewed
more thoroughly in Sections 2.2.3, 'Toxic Air Emissions,"
and 4.4, "Chemical Specialties,"
Modern batch dyeing processes use enclosed machines
that operate at superatmospheric pressures above the
boiling point of water. These machines have reduced the
need for chemical specialties such as dye carriers and
have contained many fumes and vapors that the former
atmospheric (open) machines released. These volatile
materials, however, now have a tendency to either be
forced into the substrate or discharged with the waste-
water. In the former case, the organic chemical residues
from dyeing tend to volatilize during the subsequent
drying, heatsetting, and curing (or finishing) operations
performed on the substrate. In the latter case, the vola-
tiles tend to be stripped from the wastewater systems
during secondary activated sludge biological aeration
treatment (see Section 1.2.1, "Air Pollutants").
In continuous dyeing (and printing), the fabric usually
goes through one or more cycles of wetting and drying
as it progresses down the range, and the fabric repeat-
edly undergoes high-temperature thermofixation proc-
esses. In these stages, any volatile components of the
dyeing process solutions are volatilized in the range.
Because of the high temperatures in thermofixation
ovens, even relatively nonvolatile materials (e.g., urea)
can be vaporized.
4.10.3 Pollution Prevention in Specific
Dyeing Situations
This section describes pollution problems and recom-
mended prevention measures applicable to selected
dyeing situations that involve certain combinations of
dyes and fibers. These situations cover most of the
important pollution problems—and thus represent pollu-
tion prevention opportunities—that occur within dye-
house operations.
4.10.3.1 Acid Dyes for Wool and Nylon
Acid dyes are the major class of dyes used for wool and
nylon in the United States. Bath exhaustion with acid
dyes, if performed properly, can reach 90 percent or
greater. Aside from premetalized dyes, which constitute
only a small portion of total dye use, the main concern
about acid dyeing is the BOD contribution of acetic and
formic acid and the low pH (in the range of 3 to 7).
Sudden variations in wastewater pH can produce shock
loads to the biological processes in wastewater treat-
ment systems and contribute high aquatic toxicity (1).
Many acid dyes contain metals as part of the dye
structure, Work is underway to develop acid dye re-
placements for premets, which would contain iron instead
of the more harmful cobalt, nickel, lead, chromium, or
zinc (56). This research has already produced substi-
tutes for the cobalt-containing acid dyes Acid Red 182
and Acid Blue 172 and the chromium-containing Acid
Black 172.
4.10.3.2 Chrome Dyeing for Wool
According to Shaw (7), approximately 70 percent of
wool dyed in Europe uses heavy metals, mainly chrome.
Low-chrome alternatives have been under development
since 1976. Results show reductions of chrome in efflu-
ent from about 155 ppm (for conventional dyeing) to
levels of 33 ppm, 8 ppm, and near 0 ppm for pH control,
fresh bath, and thiosulfate methods, respectively (57).
U.S. discharge regulations require essentially zero dis-
charge of chrome.
Duffield et al. (57) provide several pollution prevention
recommendations to reduce chrome discharges from
chrome wool dyeing:
• If the dyebath is not completely exhausted before
chroming, the bath should be drained. This prevents
mixing of dyeing and chroming solutions.
• The optimum pH for maximizing dye chroming is in
the range of 3.5 to 3.8. This can be attained using
formic acid instead of acetic or other acids, which
may inhibit exhaustion of the chromate ion.
• Only the minimum required amount of chrome should
be added to the bath.
180
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Table 4-37. BOD of
Class
Acid
Basic
Direct
Disperse
Fiber reactive
Naphthol (sulfur vat)
Dyeing Auxiliaries
Fiber
Wool
Nylon
Acrylic
Other
Polymers
Cellulose
Synthetic
Cellulose
(wool)
Cellulose
(ppm) (11)
Machines
Stock
Skein
Package
Jig
Beck
Jet
Beam
Stock
Package
Beck
Jet
Beam
Stock
Package
Jet
Beck
Stock
Package
Beck
Jet
Beam
Stock
Jig
Jet
Beam
Beck
Skein
Any
Chemicals
Surfactant
Leveler
Retarder
Acid
Dye
Lubricant
Salt
Surfactant
Leveler
Retarder
Acid
Dye
Lubricant
Salt
Carrier
Alkali (weak)
Surfactant
Retarder/Leveler
Salt
Lubricant
Fixative
Dye
Acid (weak)
Dispersant
Dye
Carrier
Lubricant
Reductive/Afterscour
Alkali (strong)
Salt
Dye
Dye
Lubricant
Soap-off
Reducers/Oxidizers
Dye
Lubricant
Buffer
BOD Contribution to Waste
Moderate (varies)
Varies (may exhaust)
Varies
Low
Low
Varies (may exhaust)
Nil
Moderate (varies)
Varies (may exhaust)
Varies
Low
Low
Varies (may exhaust)
Nil
Varies (may exhaust)
Nil
Varies (moderate)
Varies (moderate)
Nil
Varies (may exhaust)
Low (exhausts)
Low
Low
High
High (dispersant)
High (varies)
Varies (may exhaust)
Moderate to high •
Nil
Nil
Nil
Nil
Varies (may exhaust)
Moderate (varies)
Varies greatly
• The dyer should follow a time-temperature cycle that
is optimum for chrome dyeing, such as that dia-
grammed in Figure 4-15. This figure depicts a low-
temperature chrome dyeing technique running at
90°C. Thiosulfate is added after chroming to destroy
residual dichromate.
• Raising the temperature to between 98°C and 100°C
results in better chrome utilization and lower chrome
residual. A 7.5-percent anhydrous sodium sulfate so-
lution must be used to ensure even chrome treatment
at these temperatures. An alternative is to add chrome,
wait 10 minutes, and then lower pH to 3.5 to 3.8.
Further data illustrating the benefits of optimized chrome
techniques are shown in Table 4-38.
The discussion above relates to dyeing processes in
which the dyer adds chrome separately to the bath.
Other wool dyeing processes use dyes that contain
chrome in the dye molecule, and several pollution pre-
vention techniques are available for these as well.
For 1:1 metal complex dyes, alternatives are available
that reduce chrome residues from typical levels of 5.4
ppm to 1.3 ppm (e.g., the Neolan P class from Ciba)
(57). Sulfamic acid is used instead of sulfuric acid to
provide better pH control during heating with these dyes.
For 1:2 metal complex dyes, the techniques under in-
vestigation include use of chemical specialty assistants,
better chemical dosing and temperature controls, and
dyeing above the boiling point under pressure (57).
Using these methods, exhaustion increased by an aver-
age of 32.8 percent in one case and 8.7 percent in
another (57).
Chromium is a very offensive pollutant and should re-
ceive maximum pollution prevention attention. In addi-
tion to dyebath effluents, other sources of chrome in the
dyehouse may include spillage from handling, imple-
ment cleanup, drum washing, and incorrect weighings.
Pollution prevention measures include special worker
training, identification of problem dyes, better record-
keeping, and auditing of chromium use.
181
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Temperature (°C)
A. Auxiliaries
B. Dyes
C. Formic Acid for Exhaustion
D. Formic Acid to pH 3.5
E. Sodium Thiosulphate
20
40
60 80
Tims (minutes)
Low-Temperature Dyeing
100
120
140
Control Dyeing
Figure 4-15. Low-temperature chrome dyeing, time/temperature profile (56).
Table 4-38. Dyebath Chromium Residues With Optimized
Chroming (57)
Chroming Metals
Residual Chromium
(mg/L)
Control dyeing black
Control dyeing navy
Black 98°C, Lyocd CR (Sandoz)
Navy 98°C, Lyocol CR (Sandoz)
Black 90«C, thfosutphate
Navy 9Q*C, thtosulphate
66
83
1.68-3.50
1.00-4.30
3.00-6.00
2.50-3.50
4.10.3.3 Basic Dyes for Acrylic and Polyesters
Basic dyes are water soluble and have extremely high
affinities for acrylic and basic dyeable polyester. Shades
are brilliant, costs are low, and the dyebaths exhaust
essentially 100 percent. As cationic materials, basic
dyes tend to exhibit high aquatic toxicity if present in
wastewater (58). Assuming good spill management and
dyeing practice, however, very little dye should carry
over to the effluent stream because of the high exhaust
percentage. Pollution prevention recommendations for
these dyes therefore focus on proper handling and spill
control (see Sections 3.11, "Optimized Chemical Han-
dling Practices," and 4.18, "Support Work Areas").
4.10.3.4 Disperse Dyes for Polyester, Acetate,
and Other Synthetics
Dyeing of polyester and polyester/cotton blends com-
monly includes an afterclearing step. Afterclearing is the
process of treating disperse dyed polyester fabrics with
a reducing solution containing typically 2 percent so-
dium hydrosulfite and 2 percent sodium hydroxide owg
at 90°C for 30 to 45 minutes. Residual hydrosulfite
produces immediate oxygen demand (IOD) in the effluent.
Afterclearing sometimes is unnecessary and a waste of
water, chemicals, and time (59). On properly dyed 100-
percent polyester, for example, afterclearing should not
be necessary for most shades. With blends, subsequent
drying, heatsetting, and curing steps may cause dis-
perse dye migration from the polyester to the cotton,
from which it washes off in the washfastness test. Clear-
ing the polyester before heat treatments is often incon-
sequential to the final result if the dye is prone to migrate
(as are, for example, virtually all disperse red dyes).
New ester-type disperse dyes have been introduced
that can be aftercleared with alkali alone and that do not
require any reductive afterclearing agent. These dyes
are based on the diesters thiophene and benzodifurone,
which are cleared using only alkali (with no hydrosulfite).
In addition, the dyes based on benzodifurone resist
thermomigration, especially in red shades (59).
4.10.3.5 Fiber Reactive Dyes on Cotton and
Other Cellulosics
Fiber reactive dyeing of cotton and other cellulosics
cannot achieve the high fixation level of other fibers,
which in wool and synthetics are typically in the range
of 90 percent or higher (60). To maximize fixation, fiber
reactives require the use of large quantities of salt,
typically up to 100 grams per liter. Even with high levels
of salt added and the use of new bifunctional reactive
dyes, fixation in typical batch dyeing processes usually
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remains below 70 to 80 percent. This results in the
discharge of large amounts of color to the wastewater.
When applying fiber reactive dyes to cotton, some un-
fixed, hydrolyzed reactive dye remains in the fiber to be
washed off. The washing off process requires substan-
tial amounts of water. One alternative is to limit the
amount of washing and then fix the remaining dye (22,
23). In addition to the standard fixing agents for use in
this situation (dicyanodiamide [DCY|/formaldehyde),
several new cationic polymeric fixing agents are avail-
able that are more efficient when used with fiber reactive
dyes. These agents, now in standard use in package
dyeing, can easily be used in fabric maichines as well.
Pad-batch dyeing is an important alternative for fiber
reactive dyeing on cotton and blends and is described
in detail later in this chapter. Pad-batch dyeing has been
widely recognized as an attractive alternative in terms
of pollution prevention and energy efficiency (11, 54).
4.10.3.6 Low Sulfide Reducing Agents for Sulfur
Dyeing
Because of their extreme resistance to washing off,
sulfur dyes are preferred if the ultimate in fastness is
required (e.g., black sewing threads top stitched on
white fabric). They are also completely resistant to the
normal perborate, chlorine, and peroxide bleaches. The
drawback is that the shade range is limited—mostly dull,
dark, and earth tones.
When initially introduced in the late 1800s, sulfur dyes
were reduced in the dyehouse by boiling the dye with
soda ash and sodium sulfide to render them soluble
(61). Then, in reduced form, they were applied to cotton,
then reoxidized later in the process to produce fast
dyeings. A by-product is foul-smelling sulfur dioxide (61).
A later advance was the introduction in 1936 of prere-
duced/presolubilized sulfur dyes, thus eliminating the
need for on-site reduction processes. In the 1990s, new
types of sulfur dyes have been introduced that feature
lower sulfide content, which lowers sulfide discharges to
mill effluent as well as hydrogen sulfide odors in the mill
and in the waste treatment system. The chemical nature
of the proprietary reducer is not revealed, but it appears
from the MSDS information to be an organosulfur reduc-
ing agent (61).
Glucose or sugars from corn can also be substituted for
sulfide-containing reducing agents (3). In one case, us-
ing alternative reducing agents lowered the sulfide con-
centration from 30 ppm to 2 ppm in the effluent. A small
increase in BOD resulted but was easily handled by the
waste treatment system, whereas the sulfide waste was
not amenable to treatment. The zone settling velocity in
the clarifiers improved as a result of the decrease in
sulfide, thus increasing waste treatment efficiency.
Odors also decreased. Operating costs did not increase,
and the cost savings for avoided purchase of sufficfe
removal equipment was estimated at $20,000. Waste
treatment efficiency improvements were valued at
$30,000 per year. The corn sugars were obtained as a
waste product from the corn starch industry, which saved
the starch manufacturer $12,000 in waste treatment
expansion and $2,400 in operating expense annually.
4.10.4 Batch Dyeing Pollution Prevention
Measures
Best management practices for pollution prevention in
dyeing processes begin with careful dye selection. De-
sirable features of a batch dye include: 1) high fixation,
2) low toxicity, 3) absence of metals, 4) appropriateness
for the intended end-use, 5) correct and compatible
application properties, and 6) high probability of right-
first-time production. Dye selection is discussed more
thoroughly in Section 4.3, "Dyes."
Major pollution prevention techniques available to batch
dyers include low bath ratio dyeing, particularly ultra-
low-liquor-ratio (ULLR) dyeing, and use of automated
chemical and dye dosing systems.
4.10.4.1 Ultra-Low-Liquor-Ratio Dyeing
In dyebaths, some chemicals act on the bath and are
normally measured according to the bath volume.
Among these are salt, pH control, acid/alkali, dyebath
lubricants, and dispersing agents. Other chemicals,
such as dyes and softeners, act on the fabric and are
measured based on the weight of goods. Recently, a
" distinct trend has developed toward reduced bath ratio
dyeing among mills interested in pollution prevention
and energy conservation. Low-bath-ratio dyeing can
save energy and dyebath chemicals because energy
and chemical use in dyeing is generally a function of the
bath volume, not the amount of fabric.
The terminology of dyeing distinguishes between those
chemicals whose quantities are based on the amount of
bath and those whose quantities are based on the
amount of fabric. The terms on weight of bath (owb) and
on weight of goods (owg) are often used. An important
relationship for the dyer is:
owb = owg/L
(Eq. 4-3)
where L is the bath ratio, or, conversely,
owg = owb * L (Eq. 4-4)
An example of the effect of bath ratio can be found in
Section 2.2.2, "Discharge of Electrolytes," where the salt
required for different machines at different bath ratios
has been tabulated.
Unfortunately, many operations use cost systems that
base all chemicals and dyes owg for accounting reasons.
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When bath ratios change (e.g., when low-liquor-ratio
dyeing is adopted) the chemicals that should be owb are
then incorrect. This leads to frequent confusion among
managers and accountants, and sometimes even
among dyers. Therefore, a recommended pollution pre-
vention practice for batch dyeing is to determine whether
each chemical in the process should be owg or owb and
to ensure that everyone understands the distinction—
and its importance for pollution prevention.
Table 4-39 shows normal bath ratios for several dyeing
machines. ULLR dyeing, one form of low-bath-ratio dye-
ing, has the following advantages:
• Decreased water consumption and associated cost
savings (reduction in water purchases, reduction in
effluent volume requiring treatment).
• Decreased consumption of bath chemicals (see
sample calculation for salt in Section 2.2.2). ULLR
dyeing can reduce salt requirements by 80 percent
compared with beck dyeing and by 60 percent com-
pared with conventional jet dyeing (59).
• Increased fixation of dyes (see Section 2.2.1, "Color
Residues" on the relation between fixation and bath
ratio) (59).
• Reduced cycle times because of quicker machine
drains and fills and more rapid heating and cooling.
* Decreased energy requirements for heating the dye-
bath, which in turn lead to reduced steam and boiler
use, reduced fuel consumption, and fewer emissions
to the atmosphere from combustion.
In some fabric dyeing machines, ULLR techniques have
lowered bath ratios from 30:1 to 5:1, and in some cases
bath ratios have gone as low as 3:1. Both jet and pack-
age dyeing machines use short and compact piping and
Table 4-39. Normal (Conventional) Bath Ratios (13)
Process Machine Bath Ratio
Continuous
Exhaust
Pad at 100% wet pickup
Beck
Jet
Jig
Beam
Package
Paddle
Stock
Skein
1:1 (e.g., pad-batch)
17:1
12:1
,5:1
10:1
10:1
40:1
12:1
17:1
ULLR jet or package8
3:1 or 5:1
* Low-Hquor-raHo dyeing machines are often cited as a method of
reducing the volume of dye waste to be treated (22, 23, 54, 62). In
fact, most water used in dyeing is used for washing not as part of
the dyebath itself. The correlation between bath ratio and water use,
therefore, is not as close as it may appear.
low-volume pumps, and have better space utilization of
substrate in the kier (62). At this level of moisture in the
machine, almost no water is free. The cloth itself inher-
ently takes up about two to four times its weight in water,
and the pipes, pumps, kier, and sumps of the machine
take up the rest. Below the ratio of 5:1, insufficient water
is present to keep the pumps "wet."
ULLR Dyeing Machines
Jet dyeing and package dyeing are commonly used for
low ratio dyeing (see Figure 4-14). In jet dyeing, fabric
is placed in a closed tubular system. A jet of dye solution
is supplied through a venturi to transport the cloth
through the tube. Turbulence created by the jet aids in
dye penetration and prevents the fabric from touching
the walls of the tube. Jet dyeing machines that rely on
air transport or foam have also been available for some
time. Older machines have proven uneconomical be-
cause of the energy required to maintain the necessary
air flows, but energy requirements have lessened in
newer models, such as the Then Airflow (63). Package
dyeing machines are also used in low ratio dyeing. In
package dyeing, the yarn remains stationary, and the
dyebath is pumped through the machine cylinder.
Dye Selection for ULLR Dyeing
Dye selection for batch dyeing standard processes is
discussed in Section 4.3, "Dyes." ULLR dyeing requires
consideration of these factors, plus additional factors.
The need for additional considerations arises because
the dyebath is much more concentrated due to the
decrease in water in the ULLR system, as shown below:
Bath Ratio
Dye Concentration
(owg)
Dye Concentration
(owb)
Conventional (20:1)
ULLR (4:1)
1.0 percent
1.0 percent
0.05 percent
0.25 percent
Thus, for the same concentration owg, the ULLR ma-
chine has five times more concentrated dye in the bath.
Under these conditions, additional dye selection consid-
erations should include (59):
• High solubility (even in the presence of salt).
• Good leveling (because little water is present to as-
sist in dye migration).
• Good washing off.
• Very good right-first-time dyeing performance.
Suitability for ULLR dyeing also requires low interaction
with other dyes, low interaction with auxiliaries, and high
shear stability because the dye bath is pumped through
the machine at high rates. At high concentrations, dyes
tend to aggregate, which affects solubility and kinetic
dyeing behavior.
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Costs of ULLR
ULLR techniques involve reduced liquor ratios in the
dyebath, but simply reducing the amount of water in the
dye bath is not sufficient. Without further modification,
lowering the water level in the machine may cause pump
cavitation or poor fabric movement through the dye
chamber. Because of this, ULLR concepts generally
cannot be retrofitted onto existing dyeing machines.
Specially designed ULLR jet or package machines must
be used that feature a kier with a different configuration,
size, and shape from that found on a normal jet. All of
the pumps and pipes are low-volume versions. The
installation cost for a typical ULLR jet with a capacity of
30,000 pounds per week is around $1 million. This
translates into a $20- to $40-million investment for a
typical large dyehouse interested in converting to ULLR
dyeing. Given the long life of dyeing equipment (20
years), the high capital cost of ULLR dyeing machines
discourages replacement of still-valuable existing dye-
ing equipment (59).
4.10.4.2 Automated Dosing Systems
Dosing systems meter chemicals to dyebaths automat-
ically, as opposed to the practice of manual chemical
addition. For years, dyers have added salt and alkali to
direct and fiber reactive dyes, typically in portions of
one-quarter, one-quarter, one-half. Microprocessor-con-
trolled dosing systems extend that concept to continu-
ous dosing with a variety of profiles, such as constant
rate or variable rate. Some systems now under devel-
opment (though not yet commercially available) can
even sense dye exhaustion as it occurs and adjust the
dosing profile of salt and alkali accordingly (64).
Automated dosing systems can be optimized to deliver
the right amount of the right chemical at just the right time.
This additional control improves the efficiency and reli-
ability of chemical reactions in the dyebath, ensuring more
consistent and reproducible results. In addition, these
systems avoid the tendency to overuse environmentally
harmful chemicals, which may pass through treatment
systems unreacted or react to produce undesirable by-
products. Dosing systems also reduce handling losses
and equipment cleanup. Automated dosing systems are
commercially available and are being adopted through-
out the textile industry. A companion technique to auto-
mated dosing is the automated color kitchen, which is
discussed in Sections 4.10.5.2 and 4.18.
4.10.5 Continuous Dyeing Pollution
Prevention Measures
In continuous dyeing (and printing), the key pollution
prevention goals should be to:
• Maximize dye fixation.
• Minimize washoff.
• Avoid discards and machine cleaning waste during
startup, stopoff, and changes of color and style.
Dye fixation is accomplished with steam, dry heat, or
chemical reaction, and the ovens, steamers, and chemi-
cal pads in the continuous operation deserve close at-
tention and optimization for each recipe. High affinity for
dyes, which is so important in batch dyeing (especially
at long bath ratios), is not required for continuous dye-
ing. In fact, high-affinity dyes cause problems in continu-
ous dyeing, such as tailing and difficult washing, which
requires excessive water.
4.10.5.1 Improvements in Continuous Dye
Ranges
Continuous dyeing ranges offer certain inherent pollu-
tion prevention advantages, such as no exhausted dye-
bath to discard, high levels of fixation, the ability to reuse
washwater in countercurrent operation, reduced use of
chemical specialties, and the elimination of salt for dye-
ing cotton. Continuous dyebath ranges have drawbacks,
however, and their use has been limited in the past. For
example, knits cannot normally be dyed in continuous
processes because they cannot withstand the high
lengthwise tension. Other limitations of continuous dye-
ing are the lot size restrictions mentioned above, the
discharge of leftover mixes and pad baths at stopoff and
color changeovers, and the high pollution potential of the
cleaning agents.
Continuous ranges have steadily improved in recent
years, however, and limitations to their use are slowly
disappearing. Continuous dye ranges with short plumb-
ing runs, small pipes and pumps, and small pad-bath
troughs can reduce discarded mixes because all pad-
ding liquors in the pumps, pipes, and pads are discarded
when a new color is started. Many modern continuous
dye ranges have low stopoff losses and other desirable
features as described above. This not only reduces
pollution for shades that are run on continuous ranges
but also allows smaller lots to be run economically on
the less-polluting continuous systems. Increased use of
continuous knit dyeing ranges will result in a corre-
sponding decrease in pollution because continuous dye-
ing is generally less polluting than batch dyeing,
especially for longer runs (48).
4.10.5.2 Automated Color Kitchens
One of the most significant pollution prevention devel-
opments in textile equipment during the last 10 years
has been the development of the automated color
kitchen. Automatic color mixing and batching reduces
working losses from cleanup and disorderly work prac-
tices, and also ensures the correct amount of mix is
made every time, thus reducing discards. This applies
particularly to continuous dyeing operations, printing,
and finishing. Reducing startup and stopoff waste also
185
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makes shorter runs on continuous equipment more eco-
nomically feasible (13). Further information about color
kitchens appears in Section 4.18, "Support Work Areas."
4.10.5.3 More Efficient Washing
Washing operations consume most of the water used in
textile wet processing, and water conservation is, in
large part, related to proper control of washing. Impor-
tant aspects of washing are discussed in depth in Sec-
tion 2.2.7, "Water Conservation." Continuous dyeing
machines can be made more water efficient through the
use of flow restrictors, which control water volume. In
addition, countercurrent washing and recycle of clean
water are important features of continuous dyeing and
printing operations (46).
4.10.6 General Pollution Prevention
Measures
This section discusses general pollution prevention
techniques that are applicable to both batch and con-
tinuous dyeing. The most important general pollution
prevention strategies for dyeing operations, based on a
computer simulation model of dyeing processes, include
(65):
• Operating at the lowest possible bath ratio. This leads
to reductions in direct operating costs, water and
chemical use (because chemicals are added as a
percentage of water volume), energy use (less liquor
to heat or pump), and less effluent discharge (lower
volume being treated and lower chemical concentra-
tions). The cost of dyes remains essentially the same
because dyes are added as a percentage of the
weight of the fabric.
• Minimizing strip/redye procedures.
* Avoiding shading additions.
4.10.6.1 Minimize Use of Auxiliaries
Numerous auxiliary chemicals are used in dyebaths to
improve the efficiency of the dyeing process (see Sec-
tion 4.3, "Dyes"). Selecting dye auxiliaries that do not
interfere with dye exhaustion can improve the process
reliability of dye operations (66). Dyebath auxiliaries
typically contain surfactants that reduce dye fixation,
however, and this contributes to color in the wastewater.
Use of auxiliaries should be minimized, not only to save
the pollution associated with the chemical itself but also
to increase color yield, which in turn produces more
consistent shade repeats and fewer reworks with less
pollution.
Auxiliaries are often added to compensate for inadequa-
cies in process, equipment, or substrate design. One
way to reduce the need for auxiliaries is to optimize
processes and machinery to decrease such variation.
This improves the reliability and efficiency of the process
and minimizes the generation of pollutants (46). If aux-
iliary chemicals are used in dyeing, care should be taken
to control dispensing by accurately weighing all dyes
and chemicals.
4.10.6.2 Right-First-Time Dyeings
Without question, the most effective pollution prevention
practice is "right-first-time" dyeing. Corrective measures
such as reworks, redyes, stripping, shade adjustments,
top-ups, or adds are chemically intensive and have a
much lower chance of achieving desired quality than
right-first-time dyeing (65, 67). In most cases, the great-
est costs in reprocessing are the costs associated with
dyes and chemicals. Studies have shown that the cost
of dyeing can increase by as much as 30 percent when
dye additions are required (68). Right-first-time dyeing
leads to increases in productivity and more efficient use
of fixed capital and labor, which increases profitability.
Using data from the United Kingdom, Glover and Hill
(65) showed that a 10-percent improvement in right-first-
time production can produce a 1.7-percent decrease in
product waste and a $2.00 reduction in cost per 100
kilograms of fabric dyed.
Much of the success of efficient, right-first-time dyeing
hinges on good fabric preparation. Proper fabric prepa-
ration results in higher fixation and less repair work.
Poor preparation is a major cause of reworks and dye
corrections. Fabric preparation is reviewed in more de-
tail in Section 4.9, "Preparation."
4.10.6.3 Improved Dye Fixation
Improved dye fixation is an important key to pollution
prevention in the dyehouse (14). Mills can improve fixa-
tion and reduce chemical requirements overall by mer-
cerizing cotton yarn or fabric during the preparation
process, thus increasing dye uptake and reducing the
need for chemical accelerants (69). Mercerizing can
therefore reduce the amount of dye needed to achieve
a given shade and decrease the amount of color in the
wastewater. The tradeoff is that mercerization uses
highly concentrated (22 percent) sodium hydroxide,
which is a pollution concern. The exact shade used in
the dye process is key to the decision of whether to
mercerize.
4.10.6.4 Pad-Batch Dyeing
Pad-batch dyeing is a cold method used for dyeing
cellulosics (mainly 100-percent cotton and polyes-
ter/cotton blends) that can achieve large reductions in
pollution, energy requirements, and costs. The basic
technique is to saturate the prepared fabric with a pre-
mixed dye liquor and pass it through a padder, which
forces the dyestuff inside the fabric for greater penetra-
tion while removing excess dye solution. The fabric is
186.
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then stored, or batched, on rolls or in boxes for 4 to 12
hours. Typically, the batches are covered with a plastic
film to prevent carbon dioxide absorption and water
evaporation. While in batching, the dyestuff reacts with
and penetrates the fabric, resulting in even, consistent
color. After the reaction is complete, the fabric is washed.
Pad-batch dyeing offers several advantages over con-
ventional dyeing processes:
• No salt or chemical specialty agents are needed.
Eliminating these chemicals reduces waste as well
as chemical and wastewater treatment costs.
• More efficient use of dye leaves less color in the
wastewater and reduces water and energy consump-
tion. Wagner (14) reports fixation ratios for pad-batch
dyeing of 92 to 97 percent compared with 42 to 80
percent for reactives at a 10:1 exhaust dyeing bath
ratio.
• Dye quality is more consistent. Compared with rope
dyeing, pad-batch dyeing can attain more even color
absorbency, greater colorfastness, and much lower
defect levels (when the fabric is correctly prepared).
High-reactivity dyes used in pad-batch dyeing have
rapid fixation and stability, resulting in shade reliability
and repeatability. With highly reactive dyes, cleanup
is easy and frequent shade changes present little
problem.
• Pad-batch dyeing can be used on wovens or knits in
many constructions. Certain tubular knit styles may
develop edge marks at the fold, but new methods in
development will reduce this problem in heavyweight
styles (52).
• The simplicity and flexibility of the system allow for
use of available equipment—becks, beams, and con-
tinuous equipment for washing (63).
• Pad-batch dyeing requires a low capital investment
and offers overall cost savings, in dyes, chemicals,
labor, water, and other areas.
The following checklist serves as a reference to avoid
some of the problems common to pad-batch dyeing:
• Maintain good alkali control: The generally accepted
method is to mix the required amount of dye in 80
percent of the total necessary water, then mix the
alkali into the other 20 percent. A dual-piston pump
feeds the dye and alkali through a static line mixer
in a 4:1 ratio to create the proper mix in the pad
trough. This metering must be accurate and cali-
brated on a regular basis.
• Keep good data on bath ratios: This, facilitates adjust-
ing exhaust dye recipes. If the dyer has good infor-
mation about the dyes being used, the formulas can
be adjusted to compensate for bath ratio.
• Prepare fabric well: Effective preparation is neces-
sary to obtain consistent dyeing side-to-side and end-
to-end. The fabric should be scoured and/or bleached
with a residual pH of 7 or slightly less, and all residual
alkali, starch, and knitting oils must be removed (11).
• Maintain good temperature control: Feed only cold
fabric to the pad to avoid temperature increases. Hot
weather may necessitate keeping the mix cool by using
a cooling jacket or by feeding plain ice into the mix.
Dye Requirements
Pad-batch dyeing requires highly reactive "cold dyeing"
fiber reactive dyes. Table 4-40 contains a list of dyes that
have gained prominence (13).
Table 4-40. Examples of Dyes Used in Pad-Batch Dyeing (11)
Dye Manufacturer
Altafix CX
Cibacron F
Drimarine K
Intracron C
Levafix E(A)
Procion MX
Remazol
Sumafix
Atlantic
Ciba
Sandoz
C&K
Mobay
ICI
Hoechst
Wright
Equipment Requirements
The equipment needed for pad-batch dyeing includes a
padding unit; a batcher or material handling system; a
dye/alkali mixing device; A-frames, storage racks, and
storage boxes; and a washoff device (beam, beck, con-
tinuous).
Cost Comparison
Smith (13) compared the capital and annual operating
costs of pad-batch systems with those of conventional
exhaust dyeing based on becks. Table 4-41 shows this
comparison. Capital costs of the pad-batch equipment
are less than one-third the cost of comparable becks,
and operating costs (excluding dyes) are approximately
one-fifth. Table 4-42 compares the dye chemical costs
and reveals that pad-batch costs are generally lower, by
as much as 40 percent.
Sommerville (52) developed economic models of dye-
house costs for running 100-percent cotton and cot-
ton/polyester blends on batch, continuous, and
pad-batch equipment. The models incorporate knowl-
edge of the labor, equipment, power, steam, and chemi-
cal costs associated with each method of dyeing.
Simulated runs of various load sizes were performed to
calculate total costs and costs per pound for each
187
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Table 4-41. Cost Comparison of Pad-Batch Dyeing Machines
With Conventional Exhaust Dyeing Machines (13)a
Cold-Dyeing Conventional
Reactives on Exhaust
Cotton Pad-Batch/ Dyeing
Two-Beam 100% Cotton
Description Washoff Stands (19 Becks)
Capital Costs
Dya pad for knits,
two-beam washoff stands
19 atmospheric becks,
1,000-lb capacity each
Installation (estimated to
be 30%)
Operating Costs
Labor costs
Fuel costs
• Extra drying
Water costs
Dya costs (see
Table 4-42)
Chemical costs
• Salt
• Alkali
Total Costs
First-year capital and
operating costs
(exclusive of dye costs)
Subsequent yearly
operating costs
(exclusive of dye costs)
* Assumes processing of 193,050
$160,000
$48,000
$79,560
$52,000
$48,300
$8,700
Varies
$0
$19,112
$415,672
$207,672
Ib per week of
$570,000
$171,000
$256,360
$272,000
$98,500
Varies
$337,840
$82,820
$1,450,680
$1,047,520
100% cotton.
Tablo 4-42. Comparison of Typical Dye Costs for Pad-Batch
Versus Beck Dyeing (13)a
Color
Powder blue
Dark red
Bright yellow
Bright red
Bright blue
Light blue
Dark green
Navy
Pad-Batch
(0/lb)
30
50
35
48
55
37
46
30
Beck Dyeing
(0/lb)
40
63
50
75
70
58
70
53
* Assumes use of cold reactive dyes for exhaust dyeing.
method to determine the lot sizes over which various
techniques are most competitive. The following general
observations were made:
• Batch: For batch dyeing (jig, beck, jet), the costs per
pound decrease with lot size until machine capacity
is reached. Processing additional fabric, however, re-
quires adding another machine. The cost curve for
batch techniques is thus characterized by a series of
steps.
• Continuous: As lot size on the continuous range in-
creases, the cost per pound of fabric drops sharply
and levels off to a fairly constant value. For short lots,
the costs associated with downtime and changes be-
come a significant component of total costs.
• Pad-batch: In pad-batch dyeing, the cost per pound
of fabric increases very little as lot size decreases.
Downtime costs are minor and contribute little to the
overall cost per pound.
Figures 4-16 and 4-17 show cost-curve comparisons for
pad-batch versus jet dyeing and pad-batch versus con-
tinuous dyeing. Costs per pound for pad-batch are lower
than for continuous ranges for runs of up to approxi-
mately 4,500 pounds mainly because of the high down-
time costs of the continuous process. For all three batch
processes examined Get, beck, and jig), pad-batch dye-
ing was more economical over the entire range of load
sizes.
100-1
80-
60-
40-
20-
1 Pad-Batch
'.Jet
1,000 2,000 3,000 4,000 5,000 6,000
Figure 4-16. Cost curves comparing pad-batch dyeing and jet
dyeing (52).
100-1
80-
60-
40-
20-
Pad-Batch
Continuous
1,000 2,000 3,000 4,000 5,000 6,000
Figure 4-17. Cost curves comparing pad-batch dyeing and
continuous dyeing (52).
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4.1O.6.5 Dyebath Reuse
Dyebath reuse is the process by which exhausted hot
dyebaths are analyzed for residual colorant concentra-
tions, replenished, and reused to dye further batches of
material (70). Dyebath reuse provides a pollution alter-
native that is less costly than constructing a pretreat-
ment system (e.g., for urban-based dyehouses that lack
space for pretreatment) and reduces the volume of ef-
fluent and pollution concentrations in the effluent (71).
Both dyebath reuse and construction of pretreatment
facilities can accomplish many of the same goals (e.g.,
reducing BOD/COD loadings and flow); however, dye-
bath reuse may be a more attractive choice because of
its lower cost. Dyebath reuse generally requires a
smaller capital outlay than pretreatment systems and
offers a return on the investment in the form of dye,
chemical, and energy savings that pretreatment sys-
tems do not offer. Dyebath reuse principles can be
applied to dyebaths and bleach baths.
Dyebath reuse carries a higher risk of shade variation
because impurities can build up in the dyebath and
decrease the reliability of the process. If product quality
standards are high, then dyebath reuse may be risky. In
addition, some dyeing systems are more amenable to
dyebath reuse than others. Dyebath reuse can be reli-
ably used on dyes that exhaust quantitatively (e.g., acid
dyes on nylon, basic dyes on acrylic).
Some equipment manufacturers are providing built-in
holding tanks to store spent baths. One model (SCHOLL
BLEACHSTAR) has three holding tanks to allow reuse
of processing baths or washwaters. Other models have
pairs of kiers connected to facilitate the pumping of
processing baths from one machine to another, either
for reuse purposes or to ensure shade consistency on
double-sized loads.
The four basic steps to dyebath reuse are discussed
below.
1. Save the just-exhausted dyebath: Two alternatives
are available for saving exhausted dyebaths. In the
first option, the dyebath is pumped to a holding tank
(or to a second identical machine), while the product
is rinsed in the same machine in which it was dyed.
When the rinsed product is removed, the dyebath is
returned to the dye machine. With the second option,
the product is removed from the exhausted dyebath
and placed in another machine for rinsing. This op-
tion requires no holding tanks or pumps; however,
the product receives additional handling, and an ad-
ditional machine is needed for rinsing. For each of
the above methods, the dyebath should be cooled
with a noncontact cooling water system. Contact
cooling water would dilute the dyebath and would
increase the amount of chemicals needed for recon-
stitution.
2. Analyze the dyebath for residual chemicals: Most
auxiliary chemicals do not exhaust to a significant
degree during the dyeing process. Makeup quantity
is about 10 percent because of the amount lost by
absorption to the product. Some auxiliaries, however,
exhaust or are lost in the dyeing process and need
to be replenished more fully. Unexhausted dyestuffs
must be analyzed to determine the exact quantities
remaining in the dyebath to ensure the proper shade
in the next dyeing cycle. Dyebath analysis can be
performed using a spectrophotometer and/or guide-
lines based on specific production experience.
Equipment for this is readily available at a cost of
under $10,000. Unexhausted dyestuff is measured
by solution coloristic techniques, sometimes using
extraction techniques if the bath is turbid. Extraction
solvents include 1-octanol for basic and acid dyes
and toluene for disperse dyes. The procedure and
equipment for analyzing dye from the dyebath are
described in Table 4-43.
Table 4-43. Dyebath Analysis Equipment and Procedures (11)
Equipment Requirements Quantity
25-mL graduated cylinder
25-mL sample (separatory) funnel
20-cc glass syringe
Ring stand and rings
Cotton stand and rings
Table salt
Solvent
Sample cells
Total estimated cost
2
2
2
1
1
1 Ib
4L
4
Under $500
Procedures
1. Add 2 mL (25 g) of salt, 25 ml of exhausted dyebath, and 25
mL of solvent such as 1-octanal or toluene in succession in a
clean separatory funnel.
2. Place stopper in funnel and shake vigorously for 3 seconds.
Allow contents to separate for 3 seconds. Shake vigorously
again for 3 seconds. (This mixing action results in extraction of
dyes from the dyebath water into the solvent.)
3. Place funnel on ring stand and allow for distinct separation of
salt (bottom layer), water (middle layer), and solvent with dyes
(top layer). Solvent layer may appear cloudy because of water
in the solvent.
4. Remove stopper. Open the stopcock and allow the salt and
water layers to drain out to the sink or receptacle. Close
stopcock.
>—
5. Place two cotton balls in a clean, dry syringe. Drain solvent
layer from funnel into syringe. <
6. Allow solvent to pass through cotton balls in syringe to absorb
any remaining water, and collect in a clean, dry sample cell as
it leaves the syringe.
189
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3. Reconstitute the dyebath: Before the dyebath can be
reused, water, auxiliary chemicals, and dyestuffs
needed for the next dyeing cycle must be added to
the bath. Water is added to replace what was lost to
evaporation or to the product. Auxiliary chemicals are
added in proportion to the water added. The amount
of auxiliaries can be estimated; quantities do not
need to be exact. Finally, the amount of dyestuff to
be added is calculated by subtracting the dye quan-
tities in the exhaust dyebath from recipe quantities
for the next dye shade. For some types of dyes
(acids, basics, direct, and disperse), exhaustion is
governed by thermodynamic and kinetic laws, which
essentially do not alter the dyestuff. Other types of
dyes (fiber reactive, naphthol, sulfur, vat) undergo
chemical reaction and are rendered insoluble, re-
acted, or entrapped in the fiber in a chemically dif-
ferent form. Dyebath reuse history with these dyes
is not as extensive, but reuse may still be feasible.
4. Reuse the dyebath: With exhaust dyeing, the bath
temperature may be higher than the temperature in
a new dyebath. The starting temperature should be
checked to avoid spotting and levelness problems.
In most cases, the loss of heat during storage and
the cooling caused by addition of water are sufficient
to drop the dyebath temperature to an adequate
level. Time and energy can be saved by starting the
next dyeing at the highest possible temperature con-
sistent with desired product quality.
Dyebath Reuse Applications
The process described above has been used for many
fibers and dyestuffs. Table 4-44 shows full-scale appli-
cations (13). Specific case histories have been reported
in the literature for acid/nylon, basic (cationic)/Nomex,
and disperse/nylon (11).
Table 4-44. Dyebath Reuse Applications (72)
Product
Knit fabric
Yam package
Socks
Pantyhose
Carpet
Woven fabric
Skein
Fiber
Polyester
Cotton
Polyester/Cotton
Polyester
Polyester/Cotton
Nyton/Spandex
Nyton/Spandex
Nylon
Polyester
Aramld
Acrylic
Dyestuff
Disperse
Reactive or direct
Disperse/Reactive
or direct
Disperse
Disperse/Reactive
or direct
Acid
Disperse/Acid
Disperse/Acid
Disperse
Basic
Basic
Dye
Machines
Jet
Beck
Beck
Package
Package
Paddle
Beck
Beck
Beck
Jet
Skein
Maximizing Dyebath Reuse Benefits
If properly controlled, dyebaths can be reused for 15 or
more cycles (the range is 5 to 25). For maximum dye-
bath reuse benefits:
• Use dyeclasses that undergo minimal changes during
the dyeing process, including:
- Acid dyes for nylon and wool
— Basic dyes for acrylic and certain copolymers
- Direct dyes for cotton
- Disperse dyes for synthetic polymers
(Vat, sulfur, and fiber reactive dyes are difficult to work
with.)
• Reuse the dyebath to repeat the same shade, with
the same dyes and equipment, on the same fiber.
Reuse of a dyebath to produce a darker or lighter
shade with the same dyestuff on the same fiber is
also possible. In general, however, adding new col-
orants to the dyebath increases the degree of diffi-
culty in dyebath reuse.
Costs and savings of dyebath reuse, per dyeing ma-
chine, are given in Table 4-45.
Table 4-45. Typical Costs and Savings for Dyebath Reuse
per Dye Machine (13)
Description of Cost/Savings _ Value
Total Costs
Lab and support equipment
Machine modifications, tanks, pumps, pipes
Annual operating costs
Total Savings (Annual)
Dyes and chemicals
Water
Sewer
Energy
$9,000
$15,000 to $25,000
$1,000 to $2,000
$15,000
$750
$750
$4,500
Limits to Dyebath Reuse
Dyebath reuse is limited by fabric impurities that are not
removed during preparation and by impurities that accu-
mulate from dye diluents, salt buildup, steam contami-
nants, emulsifier systems, and surfactants. These
limitations tend to be insignificant at first but become a
major concern after many reuse cycles (perhaps 20). In
addition, specialty dyeing assistants and other materials
essential to the dyeing process may be lost by several
mechanisms. These include losses to vaporization from
open dyeing machines, exhaust onto the fabric, chemi-
cal reaction, and dye liquor carryoff by the substrate.
These losses may vary from 10 percent upward and
may vary between components of a blended chemical
specialty. To ensure best results, dyeing assistants
must be carefully screened for reuse performance. Bath
190
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(exhaust) dyeing is used for small lots, short runs, and
fast turnaround times. Dyebath reuse requires close
scheduling, which may limit the flexibility needed for
bath dyeing.
4.10.6.6 Water Reuse
Water reuse is becoming more prevalent and at least
one dyehouse in Germany produces 20 tons per day of
dyed knit with zero effluent water ((30). With proper
dyebath compositions, dyeing in a "standing bath" is
possible (i.e., dyeing many lots in the same bath rather
than using a new bath for each). This has the potential
to save up to 60 percent on water consumption and total
organic carbon (TOG) load in the effluent (60). Several
conventional dyehouses in the United States operate
without any special treatment equipment and achieve
partial process and noncontact cooling water recycle of
up to 30 percent. Also, several dyers in the United States
dye multiple lots in the same bath. In almost all cases,
these dyers are dyeing noncritical products, such as
work gloves or hosiery that do not have extremely high
quality standards. The savings of time, chemicals, pol-
lution, and energy in these cases are substantial. (Sec-
tion 2.2.7, "Water Conservation," describes water use in
detail.)
4.10.6.7 Better Controls
Improved dyeing machines have features that facilitate
right-first-time dyeings, such as accurate process con-
ditions (e.g., pressure sensors, chemical feeds). Also,
improved controllers are available to accept and inter-
pret these data, enabling the operator to improve exist-
ing control protocols and implement entirely new control
strategies. These are reviewed in Section 3.18, "Im-
proved Process Controls."
4.10.7 Emerging Pollution Prevention
Technologies
Several pollution prevention techniques are emerging
from pilot and laboratory studies and may receive in-
creased attention in the coming years,. Among these is
supercritical fluid (SCF) dyeing, which uses carbon di-
oxide (CO2) as the fluid medium for disperse dyeing on
synthetics. No water or pollution is associated with the
SCF process. Also, the CO2 evaporates without any
applied heat, yielding energy savings (60). SCF applica-
tion in textile dyeing is presently being researched;
large-scale commercialization is likely several years
away.
4.11 Printing
The following table introduces the pollutants and waste
streams discussed in this section, as well as suggested
pollution prevention activities for each.
Pollutant or Waste
Stream
Pollution Prevention
Actions Described
in This Section
Comments
4.11, Printing
Suspended solids
Hydrocarbons, VOCs
and PRs
Water
Color
Solvents
Ammonia nitrogen
Aquatic toxicity
Foam
General
Clean up property; avoid
discards by proper
scheduling and planning
Use polymer print pastes
(not varsol based) and
other nonvolatile alternatives
Reuse; use countercurrent
washing
Train workers to encourage
good work practices; clean
screens
Clean up properly; avoid
excessive machine and
screen cleaning by proper
scheduling and by dry
capture procedures
Avoid urea (steam can
often be used as a
substitute)
Avoid excessive machine
and screen cleaning by
proper scheduling and by
dry capture procedures;
avoid use of metal-based
dyes
Arrange processing so that
excess foam is recovered,
not dumped; avoid process
stopoffs
Maintain equipment
properly; use automated
chemical systems; examine
printing alternatives (e.g.,
transfer, ink jet,
xerography); involve
customers at the design
stage
Printing, like dyeing, is a method for applying color to a
fabric. Whereas dyeing is best suited for solid coloring of
fabrics or for applying simple geometric patterns, print-
ing can be used to apply intricate patterns or designs.
Printing generally is limited to prepared fabric, although
with some methods, printing may be dope before the
cloth is manufactured. Dyeing can be done on fibers,
yarns, or cloth after they have been woven or knit.
In printing, the color, which is usually in the form of a
paste, is deposited on the fabric using a variety of
machinery and techniques. The fabric then is treated
with steam, heat, or chemicals to fix the color. Localized
application of color requires careful cloth preparation to
ensure optimal absorption of the print paste without
spreading. Print pastes also must be formulated care-
fully to ensure proper flow properties during application
(thixography) and to ensure they remain in place from
application until drying (73).
191
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4.11.1 Printing Techniques
The major commercial printing methods are: .
• Pigment printing: Pigment printing is a common
method used with all fabric types. Pigments and bind-
ers are padded onto the fabric and then cured. Like
continuous pigment dyeing, pigment printing is a
cheap, simple process. It produces printed fabrics
with color, fastness, and other properties that are
adequate for many end-uses.
• Wet printing: Wet printing uses fiber reactive dyes for
cotton or sometimes other types of dyes, depending
on the fibers being printed. The dyes are fixed by
steam, dry heat, or chemical reaction, similar to con-
tinuous dyeing. Because wet printing uses pigments
without binders, the cloth is softer and has better
color fastness than pigment-printed fabrics, espe-
cially in the case of darker colored shades of fabric.
• Discharge printing: Discharge printing creates pat-
terns on fabrics by removing color. A dischargeable
dye is first padded onto the fabric to produce a solid
color material. The discharge or stripping/bleaching
agent then is applied to the cloth, producing "dis-
charged" areas that show the underlying solid-color
material. Discharge printing is chemically similar to
the afterclearing process in dyeing.
• Carpet printing: Special techniques are used to print
carpets, including foam, spray, and ink drop methods.
Tables 4-46 (a) and (b) show results from a recent
survey of printing worldwide and indicates the preva-
lence of various printing methods and dye classes in
different parts of the world (74). As seen, rotary screen
printing is the most common printing technique used in
North America, and pigment dyes are the most common
type of dye used.
4.11.2 Pollutants Associated With Textile
Printing
Textile printing, like dyeing, generates varying amounts
and types of pollutants. Table 4-47 presents the main
pollutants associated with printing and identifies their
sources. Printing produces high BOD and COD loads
only if preparation operations (scouring) are done on
site. Information on preventing pollution from prepara-
tion operations is covered in Section 4.9, "Preparation."
Print application consumes less water and produces
less BOD than preparation operations such as desizing,
scouring, and bleaching. Provost (76) reported that, in a
typical print plant, printing contributed only 6 percent of
BOD to the total pollutant load and accounted for 7
percent of water consumption (see Table 4-48). Print
washing, on the other hand, uses more than one quarter
of the total water in the mill but produces only 1 percent
of the total BOD load.
Table 4-46(a). Survey of Printing Techniques: By Application
Method (74)
Method
Extent of Application
Hand 1.5% (worldwide)
Mostly custom work in Far East
Transfer 6% (worldwide)
Percentage remaining steady
Flatbed 3% (United States)
Used in United States for mainly custom work
Roller 17% (worldwide)
Decrease from 63% in 1970
Rotary screen 75% (United States)
Increasing annually
Table 4-46(b). Survey of Printing Techniques: By Dye
Class (74)
Dye Class
Pigment
Reactive
Vat
Disperse
Naphthol
Acid
Extent of Application
66% (United States)
Recently declining
6% (United States)
10% (United States)
Not reported
3% (worldwide)
6% (United States)
Table 4-47. Pollutants Associated With Textile Printing and
Their Sources (11,17, 22, 23, 75, 76)
Pollutant
Typical Source(s)
Suspended solids Discarded print paste and clear
(pigment printing)
Urea (nutrient) Print paste (wet printing)
Air emissions Drying/curing oven emissions (solvents,
acetic acid)
Solvents Nonaqueous oil/water thickeners
Machine cleaning
Screen cleaning
Aquatic toxicity Surfactants
Solvents
Color Discarded print paste
Color kitchen operations
Implement cleaning
Metals ' Discarded print paste
Photo operations
Reducing agents in discharge printing
Screen making
Engraving operations
Water (and heat) Washing of printed cloth
Desizing operation
BOD Preparation, if on site
Foam Back-coating operations
Carpet printing
192
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Table 4-48. Water and BOD Generated by Process
(Percentage of Total Waste) (76)
Process
Desizing
Scouring
Bleaching
Mercerizing
Dyeing
Printing
Washing off
Finishing
Total
Water (%)
5
1
46
2
8
7
30
1
100
BOD (%)
22
54
5
0
5
6
1
7
100
Figure 4-18 categorizes pollutants according to the
scheme developed in Section 2.1. A description of each
category and applicable pollution prevention strategies
are presented below:
• Hard-to-treat wastes include color residues, metals,
phosphate-containing chemicals, nitrogen-containing
chemicals, and nonbiodegradable organic materials
(such as some surfactants and solvents). These
wastes resist effluent treatment and can pass through
conventional activated sludge treatment systems. For
the textile printer, alkyl phenol ethoxylate (APEO)
based surfactants, "white spirit" solvents, and print
pastes containing urea are the most difficult wastes
to manage. APEO and white spirit solvents can be
replaced with more biodegradable products. Print
pastes are of concern because urea, which is used
in the pastes, contains ammonia-nitrogen nutrient
characteristics. Several options are available for re-
ducing or eliminating urea in print pastes. These op-
tions are discussed in Section 4.11.3.
• Highly dispersable wastes include effluent from print
thickener systems, which produce high TSS/COD/
BOD levels in the effluent, and air emissions. Cur-
rently, the most effective way to eliminate or reduce
thickener systems is through automated color kitch-
ens and careful monitoring of textile printing machine
requirements, which can reduce the amount of print
paste that is prepared and used. Systems to recover
or recycle thickeners from effluent are being tested
in sizing applications but have not yet been used by
textile printers.
• Offensive or hazardous wastes include metals and
other pollutants from degraded dye, and immediate
oxygen demand (IOD) from reducing agents used in
discharge printing (75, 76). Organic solvents used for
screen cleaning also are included in this category
(75).
• High volume wastes include water from fabric prepa-
ration and print washing off. Although washing pro-
duces large volumes of wastewater, it does not
produce a heavy BOD load. The major BOD source
is preparation, particularly desizing and scouring.
Other targets for pollution prevention include chemicals
containing ammonia nitrogen (notably urea), phos-
phates, APEO surfactants, and Stoddard solvent (76).
4.11.3 Specific Pollution Prevention
Strategies
4.11.3.1 Oils/Hydrocarbons
Perhaps the greatest pollution problem of the past in
textile printing has been the discharge of oil/water emul-
sions, which form the basis of printing paste. These
emulsions have the desirable thixotropic rheology that
printing demands (i.e., high viscosity under normal con-
ditions with high flow under the application of shearing
forces). Yet, these emulsions also produce substantial
amounts of fats, oils, and grease (FOG) in wastewater
and cause the atmospheric release of hydrocarbons
from drying and curing ovens. Emulsions have now
been largely replaced by synthetic polymers, similar to
those used for warp sizes. A relatively small percentage
of synthetic polymer (perhaps 2 percent) is required for
thickening printing pastes to produce the correct rheol-
ogy for printing, compared with 70 percent deodorized
kerosene in the old method (22, 23). Table 4-49 com-
pares typical recipes for oil- and synthetic-based print
pastes.
In applications where oil emulsions are still used, biode-
gradable vegetable oils often are used instead of mineral
Pollution Control in Textile Printing
Remove Undesirable Process
Waste From One Medium and
Capture It on Another
Source Reduction in Textile Printing
Hard-To-Treat Waste
Highly Dispersible Waste
Offensive/Toxic/Hazardous
Waste
High-Volume Waste .
• Urea in Procion P (ICI) Dye Recipes
• APEO in Print Paste/Wash Liquors
• Solvent in Print Pastes
• Print Paste From Screen/Blanket
Washing/Washing
• For Discharge Styles, Switch to
Discharge/Resist Methods
(e.g., Alkali Discharge With
Dispersol PC [ICI] dyes)
• Washing Off After Fixation
System With Increased
Fixation/Improved Washoff
Figure 4-18. Source reduction of chemicals in textile printing
(76).
193
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oils because vegetable oils are easier to treat in waste-
water (23, 23).
4.11.3.2 Discharge Printing: Reducing Agents
Reducing agents required in discharge printing contrib-
ute IOD to the wastewater as well as metals, if the
reducing agent is metal based. Until recently, the com-
mon discharge (reducing) printing process for polyester
involved the following steps:
1. Anthraquinone dyes (applied overall in a standard
dyeing) were used to create a "ground" shade. Dyes
selected for this step were resistant to the discharge
process.
2. An easily discharged (reduced) azo dye was se-
lected for overpadding (without fixation).
3. A discharge agent was overprinted according to the
desired pattern.
4. The fabric was then steamed or heated. This fixed
the overpadded azo dye on the polyester'fabric,
except where the discharge agent destroyed the
overpadded azo dye, allowing the ground shade to
show through.
The discharge agents of choice were based on heavy
metal salts, including stannous chloride, zinc formalde-
hyde sulfoxylate, cuprous acetate, or similar heavy met-
als, which washed off into the wastewater during
afterwashing of the printed fabric (17). Modern practice
favors the use of nonmetallic discharge agents (e.g.,
sodium hydrosulfite).
Additional new technology is available that uses ester-
based dyes instead of azo dyes (e.g., Dispersol PC from
Id) for overpadding. These new dyes can be dis-
charged with alkali-based discharge agents (17), elimi-
nating the need for reductive discharge agents. The
alkali destroys the ester link and no reducing agent is
needed, thus eliminating the pollution problems with
Table 4-49. Print Paste Recipes (Parts per 1,000 of Total Print
Paste) (22,23)
Ingredients
Water
Emulsifler
Binder
Kerosene
Thickener
Pigment (dye)
Catalyst
Total mix
Pollutants
Oil-Based
100
10
150
700
0
20
20
1,000
900
Synthetic
Polymer-Based
815
0
150
0
15
20
0 .
1,000
185
metals and IOD. These are similar to the alkali-clearable
disperse dyes described in Section 4.10, "Dyeing."
4.11.3.3 Transfer Printing
Transfer printing, also known as sublistatic transfer
printing, is the newest, fastest growing printing method.
This technology exploits the properties of disperse dyes,
which sublime when heated (i.e., the solid dye vaporizes
and is deposited as a solid upon another surface). With
transfer printing, disperse dyes are printed on paper
using fast, cheap, and efficient printing methods. The
paper then is placed in contact with a synthetic fabric
(usually polyester) under high pressure and heat (about
300°F). The solid dyes vaporize and, because they have
a greater affinity for the cloth than for the paper, deposit
themselves onto the cloth in the exact pattern printed on
the paper. Transfer printing can be performed at rela-
tively high speeds because the cloth rapidly absorbs the
dyes.
Because most transfer printing is done on polyester (or
high-percentage polyester blends), dyes must be insol-
uble in water. Dyes that are compatible with transfer
printing include disperse dyes and solvent dyes (77).
Transfer printing can produce patterns of any design or
color. The paper, however, must be compatible with the
fabric width. This method of printing is economical for
short runs, one of a kind items, and piecework, and for
frequent color or pattern changes, because no cleanup
is required. For larger runs, rotary screen printing is
more economical. Transfer printing also is useful for
applying designs on cloth, cut panels, and finished gar-
ments and is best suited for manmade fibers such as
polyester, nylon, and some acrylics. A major advantage
of transfer printing is that quality control can be per-
formed on paper before printing, minimizing fabric
waste.
In transfer printing, many pollution prevention problems
that would otherwise be the responsibility of the printer
(e.g., color mixing, cleanup, effluent treatment) shift to
the transfer paper manufacturer. The net benefit for the
environment depends on the practices of the transfer
paper manufacturer and the printer. From the printer's
standpoint, transfer printing offers several advantages.
In contrast with conventional printing methods, transfer
printing deposits only the dyestuff on the fiber; no other
chemicals are involved in the printing process. For this
reason, the process requires no afterwashing and, as a
result, generates no effluent. Although conventional
printing methods require up to 250 kilograms of water
per kilogram of textile, transfer printing requires a mini-
mal amount of water, perhaps 2 kilograms per kilogram
of textile. Other advantages of transfer printing include:
• Dyestuff consumption is lower.
• Less energy is used.
194
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• No after-treatment (e.g., steaming, washing, drying) is
required, lowering costs.
• Less production space is required.
• Less skilled personnel are required.
« Less pollution is generated.
• Inspection of cloth and paper before printing elimi-
nates costly seconds.
Nonetheless, transfer printing has several disadvan-
tages. First, it is limited to volatile dyes and the fibers for
which such dyes show an affinity. Second, this method
is most appropriate for synthetic fibers; it does not work
with natural fibers. Third, dye penetration is limited be-
cause only a small quantity of dyestuff generally is de-
livered to the paper. Penetration can be a problem
particularly for knit goods, which, when stretched, will
show the ground color (3).
4.11.3.4 Ink-Jet Printing
Ink-jet printing is a noncontact printing method in which
droplets of colorant solution are propelled toward a sub-
strate and directed to a desired spot (78). Ink jet is an
emerging technology in the textile industry and has not
yet been adopted for widespread commercial use. Ink-
jet printing lends itself to computerized control, offering
several benefits, including pollution prevention.
The dye types most amenable to ink-jet printing of tex-
tiles are fiber reactive, vat, sulfur, and naphthol dyes
because one essential component can be put in the
droplet while another can be applied to the substrate, as
shown in Table 4-50. Other conventional dye types (i.e.,
acid, basic, and disperse dyes) can be applied and fixed
with heat or steam. Those listed in the table, however,
produce a reaction upon impact.
Ink-jet printing offers several advantages (60, 79):
• Eliminates the need for photographic screen making,
which contributes silver to the effluent stream.
• Eliminates messy color-mix kitchen activities.
• Offers the potential for instantaneous pattern or color
changeover without cleanup waste or fabric loss.
• Eliminates the need for thickeners and clears (kero-
sene, Stoddard solvent, or synthetic polymers).
Table 4-50. Ink-Jet Dye Types (78)
Dye Class Droplet
Substrate
Fiber reactive
Naphthol
Sulfur
Vat
Dye
Diazo salt
Reduced dye
Reduced dye
Alkali
Naphthol coupler
Oxidizer
Oxidizer
• Eliminates screen, squeegee, and machine cleaning
wastes.
• Offers the potential for direct computer control of
printing, which reduces seconds, strikeoffs, and other
wastes.
The ink-jet technique is used widely in document print-
ing, and its application to textile printing is relatively
straightforward. Recipes for suitable colorant solutions
based on commercially available dyes and chemicals
have been published in the textile trade literature (78).
Prototype printers are available from Iris Graphics (New
Jersey), Stork (Switzerland), Wilcox (Australia), and
others.
4.11.4 Pollution Prevention Practices
Throughout the textile printing industry, printers, machin-
ery manufacturers, chemical suppliers, and marketing
agents are developing an awareness of environmental
issues (79). The main components of a successful pol-
lution prevention program in printing plants are raw ma-
terial conservation, product substitution, process and
equipment modification, material handling, scheduling,
and waste recovery (79). More specific pollution preven-
tion measures also can be implemented to reduce the
amounts of pollutants associated with printing, as de-
scribed in the sections below.
4.11.4.1 Design-Stage Planning
The planning stages of printing processes and products
offer opportunities to "design in" pollution prevention.
Specifications for screens, tanks, homogenizers, and all
other equipment are crucial because of the inherent
difficulty in cleaning printing pastes. The design of the
fabric and pattern (e.g., dye selection for colors that
require no metals) is similarly important and can affect
the overall environmental impacts from printing. Other
areas to address to minimize machine cleaning include
maintenance, cleaning, nonprocess chemical control,
and production scheduling. These issues are discussed
more fully in other sections of this document.
4.11.4.2 Surfactants
Surfactants, which are used widely in textile printing,
should be carefully selected because of their pollution
potential. Surfactants provide the correct print paste
penetration properties and, in some cases, adjust the
rheology of the pastes. They are a primary component
of both conventional and foam-type print pastes. Surfac-
tants are also used for afterwashing of printed goods.
The criteria for selecting surfactants in printing are the
same as those for preparation, dyeing, and other opera-
tions. As in almost every other textile process, a good
understanding of surfactants is essential because they
195
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are one of the main causes of aquatic toxicity and BOD
in textile wastewater. Many types of surfactants are
available, and selecting the correct one requires a good
understanding of several subtle issues, as discussed in
Section 4.4, "Chemical Specialties." The most popular
surfactants are the nonionics, and of these, the most
degradable are the LAEs. These products combine ex-
cellent wetting properties, good biodegradability and
reasonable cost and, therefore, are the products of
choice at this time. For a full discussion of nonionics,
see Section 4.4, "Chemical Specialties."
4.11.4.3 Air Emissions
Air emissions from fixation steamers and ovens can be
reduced by using nonvolatile pH buffers such as mono-
sodium phosphate (MSP) in place of more volatile pH
buffers such as acetic or formic acid. (The subject of
hydrocarbon emissions from solvent thickeners was
previously discussed in Section 4.11.3.1.)
4.11.4.4 Chemical Expertise
For the printer, chemical expertise is as important as
textile design and knowledge of printing techniques.
Most designers and printers are not aware of the envi-
ronmental consequences of specific colors or paste
types that they select for patterns (see Section 3.2,
"Design-Stage Planning for Facilities, Processes, and
Products").
4.11.4.5 Maintenance
Equipment maintenance procedures are very important
in printing. Printing operations are inherently messy, so
equipment often falls into disrepair. Print pastes dripping
on the floor from printing machines as well as leaking
pumps, pipes, and containers are not uncommon in
printing plants. Workers can develop poor attitudes
about housekeeping as a result. Forthat reason, training
programs to bolster worker attitudes and to optimize
chemical handling practices are important.
4.11.4.6 Water Conservation
High-extraction, low-carryover process step separations
should be implemented for water conservation in after-
washing of prints. The purpose of high extraction be-
tween sequential washing steps in multistage print
washing is to prevent impurities from carrying over into
downstream wash boxes (i.e., to prevent carryover). To
effectively remove unfixed dye and other print paste
components by washing, as much water as possible
must be removed between washing steps. Water that is
not removed will carry over and contribute to washing
Inefficiency. In continuous print washers, extraction be-
tween steps can be done with high-extraction pad rolls
or with vacuum extractors. Countercurrent washing is a
widely practiced, effective method for reducing water
consumption. Equipment to reduce carryover is de-
scribed under Section 3.19, "New Equipment." For a
more complete description of this entire subject, see
Section 2.2.7, "Water Conservation."
4.11.4.7 Alternative Technologies
In developing pollution prevention strategies, mills
should consider process alternatives such as pigment,
wet, discharge, or transfer printing, as well as emerging
technologies such as ink jet. In addition, mills should
also examine chemical alternatives such as the use of
polymers instead of oil/water emulsions.
4.11.4.8 Markets for Waste
Markets for printing wastes exist but are largely un-
tapped. Spent printing pastes could, for example, be
mixed with concrete to impart color and toughness (from
the polymer content of the pastes). To benefit from reuse
opportunities, printers must segregate print pastes from
other wastes and capture them in as pure a form as
possible. See Section 3.9, "Developing Markets for
Waste" for further information.
4.11.4.9 Color Shop Practices and Print Paste
Handling
In a print plant, the color kitchen is the main source of
solid and liquid waste. Wastes from kitchens include
excess and off-color pastes as well as wastes generated
from handling and dispensing chemicals and from wash-
ing containers and equipment. Print pastes adhere to
every implement and container (dippers, mixers, tubs,
homogenizers, drums, screens, stirrers, and squee-
gees), typically creating messy color shop operations. In
addition to solid wastes, color kitchens also account for
a surprisingly large share of the total effluent color load,
even more than washoff operations (79).
Automated print paste makeup apparatus eliminates
spills caused by human error (and subsequent clean-
ups) as well as the amount of leftover paste to be
disposed of at the end of a run (76). Numerous vendors
supply apparatus for automated print paste makeup,
along with modern color dispensing. The advantage of
automated print paste makeup is that the printer can
reproduce a paste recipe in any amount at any time. For
example, with conventional mixing, printers make up 50
gallons of a paste recipe when only 37 gallons are
needed in case they run out of that particular recipe at
the end of a print run. The result is 13 excess gallons of
paste. With automated print paste makeup, however, as
little as 5 gallons of a particular recipe can be made up
at any one time. If the paste runs out near the end of a
run, more of the same recipe can be reproduced quickly
and easily.
196
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Reducing the length of pipe runs reduces startup,
stopoff, and cleanup print paste waste (79). Modern
equipment (pumps and squeegees) are of lower volume
configuration, which also reduces the amount of such
wastes. See also Sections 4.18, "Support Work Areas,"
and 3.19, "Pollution Prevention Through New Equipment."
The importance of worker attitudes toward pollution pre-
vention cannot be overemphasized in color shop prac-
tices and print paste handling. Companies must instill a
pollution prevention ethic in workers, even in the face of
disorder. The proper attitude can have tremendous posi-
tive impacts.
Another important pollution prevention practice to imple-
ment is dry capture and segregation of solid wastes and
print pastes at every possible point in the operation. Dry
capture involves wiping off equipment such as imple-
ments, screens, and mixers, and containing print pastes
in their concentrated form before they become diluted.
Pastes then can be dried until solid (perhaps 10 percent
of the original weight and volume) and incinerated or
landfilled. All print operations, including screen washers
and drum washers are potential points of control.
Once mixed, the shelf life of fiber reactive print pastes
is very short (79). The use of low-reactivity dyes and
proper timing of the print paste makeup can help to
prevent pastes from expiring on the shelf. Automated
mix kitchens are extremely important in this regard be-
cause they allow the printer to make up several small,
consistent batches of paste over the course of a produc-
tion run (48). Without automated mix kitchens, the
printer must select between one large but consistent mix
that ages and many smaller but less consistent mixes,
which are made up as the run progresses.
Alginates are the preferred thickeners for fiber reactive
dyes because they do not react with the dyes. Pastes
thickened with alginates, however, are susceptible to
microbial attack and will spoil. Biocide additives can
prevent microbial attack (79). Timely mix makeup and
automated color kitchens also can prevent the need to
dispose of obsolete print pastes (79).
Air emissions from printing operations are associated
with fixation (79). The major pollutants result from vola-
tilization of oils, hydrocarbons, and acetic acid. As men-
tioned previously, synthetic polymer thickeners and
MSP are chemicals that can be substituted to reduce or
eliminate these problems.
4.11.4.10 Print Paste Reuse
When producing special colors for customers, excess
pigment print paste can be held in inventory until a
suitable use is identified (80). Pastes have a finite shelf
life, however, and must be discarded if kept too long.
Proper management of pastes to maximize their reuse
potential can have a significant impact on the amount of
wasted paste. In one case study, a facility reduced the
amount of print paste that was landfilled by 90 percent
simply by appointing an experienced color mixer to the
position of "master of reuse." This person reviewed all
orders for new colors and determined which of the
stored excesses could be mixed to produce desired new
colors (81).
4.11.4.11 Urea Replacement in Fiber Reactive
Printing
Urea is used as an additive in reactive print pastes,
especially for rayon, because it has the following prop-
erties that aid in the printing process:
• Swells the cellulose fibers before steam fixation of
fiber reactive dyes.
• Causes dyes to disaggregate.
• Increases the solubility of dyes.
• Retards the evaporation of water during drying.
• Increases the condensation of water on the print dur-
ing steaming.
The benefits of using urea include increased solubility
of the reactive dye in the print paste, improved color
yield, and improved levelness and smoothness of the
printed area, especially with viscose fabrics (79).
Although urea offers several technical advantages, the
printing industry has targeted it for elimination because
it contributes nitrogen to the effluent stream (76). Sev-
eral experimental methods are being evaluated for elimi-
nating urea, including two-stage printing (flash aging),
use of alternate nonnitrogen chemicals, and prewetting
before steaming (76, 79):
« Flash aging involves a multistep process: printing
with highly reactive dyes, drying, overpadding with
alkali/salt bath, then high-temperature steaming
(125°C for about 1 minute) (79). This method does
not use urea, but it uses more alkali. Although one
pollutant is substituted for another, urea is generally
thought to be more of a problem than alkali.
• Chemical substitution with nonnitrogen chemicals
has been unsuccessful so far. One possible "substi-
tute for urea is dicyanamide, which contains nitrogen
but is less polluting than urea. Table 4-51 compares
urea amounts from prints on cotton using urea alone
and urea in combination with 15 grams of a urea-free
proprietary printing assistant per kilogram of print
paste. The reduced urea amounts range from 5.6 to
59.4 grams of urea per kilogram of paste, depending
on dye selection and depth of shade. Combining urea
with a proprietary printing assistant can reduce urea
use by up to 80 percent.
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Table 4-51. Comparison of Relative Color Values From Prints
on Cotton With Matexil FN-T-Treated/Reduced
Urea Recipe and Near-Optimum Urea Alone (76)
Urea Alone Recipe
Dye
Con-
centra-
tion
Procion (g/kg)
Yeltow SP-8Q 40 liquid
Yellow P-3R 33 liquid
Orange P-2R 40 liquid
Scarlet P-2R 33 liquid
Red P-4BN 33 liquid
Red P-8B grains
Brown P-4RD 25 liquid
Blue P-3R 40 liquid
Blue P-GN 40 liquid
Biua P-5R 40 liquid
Turquoise H-A 25 liquid
Turquofso P-GR 50 liquid
Navy P-2R 40 liquid
Black P-N 50 liquid
Black P-2R 40 liquid
120
150
120
150
150
40
200
120
100
120
120
90
150
140
150
Con-
centra-
tion
(g/kg)
75
75
75
75
75
75
75
50
75
50
100
75
75
75
50
Relative
Color Value
for 20 g/kg
Relative Urea Plus
Color FN-T Recipe
21.8
32.9
36.6
41.8
38.7
38.1
57.1
21.7
27.8
36.5
21.7
16.3
52.6
50.6
60.8
21.8
32.3
36.5
41.2
40.7
34.5
50.7
20.2
26.2
26.2
11.7
15.3
52.6
57
58.4
• Prewetting involves the use of moisture mist systems
to prewet fabric to a wet add-on of 30 percent imme-
diately before steaming. Prewetting attracts moisture
to the fabric during steaming, which is one of the
main functions that urea performs. These methods,
however, are not as effective on rayon as they are
on cotton. As shown in Figure 4-19, rayon printing
is more complex. With proper attention, however,
reduced-urea recipes can be used for rayon as
well. Table 4-52 presents typical urea reduction
amounts (76).
4.11.4.12 Silver
Many textile printers use photographic techniques for
color separations and screen making. Silver is a highly
toxic by-product of these processes. One photographic
firm recovers silver from processing solutions by elec-
trolysis, resulting in a 96-percent reuse rate for fixer
solutions and an 84-percent recovery rate for developer
solutions. The recovered solutions have a value of $1.1
million per year. The recovered silver is worth $800,000
annually (75).
Ink-jet printing (an emerging technology) and computer-
driven laser screen making equipment (a new but
proven technology) directly digitize patterns and elimi-
Singe
Desize
Relax/Scour
(Continuous or Batchwise)
Stenter Dry
'
No Pretreatment
'
I
Causticization with 8' Be
NaOH, Washoff
Urea Pretreatment
100 to 200 g/kg
< i
Senter Dry
1
Cotton Recipe
With 100 g/kg Urea
in Print Paste
No Urea in
Print Paste
Reduce Urea in
Print Paste 80 g/kg
Urea* 15 g/kg
Matexil FN-T
High Urea in
Print Paste
200 g/kg
Water Spray Application
With WEKO or
Farmer Norton SD
Spin Applicators
Conditioning by
"Cooling" or Spray
Dampening With
Steam
Steam Under Atmospheric Conditions,
102'C, 5 to 10 Minutes, 100% r.h.
Washoff
Dry
Figure 4-19. Schematic of rayon preparation/printing (76).
nate the need for photographic processes that produce
toxic silver in effluent (78).
4.11.4.13 Synthetic Polymer Thickeners for
Oil/Water Systems
The rheology requirements for screen printing pastes
are quite specific. The pastes must be thixotropic, mov-
ing easily through a screen when exposed to shearing
force but remaining immobile (e.g., stationary on the
fabric during steaming) when not under shearing force.
Thixotropy traditionally is achieved by using water emul-
sified in oil, about 30 parts water to 70 parts oil, along
with an emulsifier/surfactant. Recently, synthetic and
natural polymer solutions with the same properties as
oil/water emulsions have been developed for use as
thickeners.
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Table 4-52. Comparison of High-Urea Print Recipe Versus
Reduced-Urea Recipe on Causlicized Viscose
(Relative Color Values) (76)
• Ink-jet printing (78).
• Systems to reclaim and reuse print paste thickener
Procion
Yellow SP-8G 40 liquid
Yellow P-3R 33 liquid
Red P-4BN 33 liquid
Violet P-3R grains
Blue P-3R 40 liquid
Blue P-5R 40 liquid
Turquoise P-GR 50 liquid
Navy P-2R 40 liquid
Brown P-4RD 25 liquid
Black P-N 50 liquid
Black P-2R 40 liquid
Control Recipe
200 g/kg Urea
17.2
26
36.7
36.9
14
31.4
8.9
23.4
47.1
43.6
46.7
Reduced-Urea
Recipe
80 g/kg Urea +
15 g/kg Matexil
FN-T
18
31.3
39
32.8
13.8
30.1
6.2
18.5
40.1
47.2
46.6
(analogous to size recovery systems) (76).
• Alginate recovery and reuse. These are natural prod-
ucts that can be reused in a fashion similar to size
to reuse; however, different technologies are involved
(79).
4.12 Finishing
The following table introduces the pollutants and waste
streams discussed in this section, as well as suggested
pollution prevention activities for each.
Pollution Prevention
Pollutant or Waste Actions Described
Stream in This Section Comments
4.12, Finishing
General Design fabrics to require .
minimal chemical
finishina: use menhaninal
In addition to synthetic and natural polymers, pigment
binders also can be used as thickeners, but a cross-
linker (e.g., melamine) must be used to provide durabil-
ity (75). Other additives to the print paste contribute to
BOD and COD, much like warp size additives (75).
Natural polymers are easily degradable and do not pro-
duce hazardous or difficult-to-treat effluent (75). Emul-
sions contain hydrocarbon oils, which can be hard to
degrade and can produce hydrocarbon air emissions.
Emulsions also exhibit aquatic toxicity (75). Synthetic
polymer thickeners are less degradable than emulsions
and are analogous to synthetic warp sizes. In fact, most
of the polymers used as thickeners are the same as
those used as warp sizes (75).
Water-soluble thickeners used in printing are similar to
warp size materials. Therefore, similar pollution preven-
tion considerations apply (27).
4.11.4.14 Washing
In washing off, high-efficiency counterflow washers can
conserve up to 30 percent of the water and energy used
by conventional washers (79). Less-polluting synthetic
thickeners are generally used in place of oil thickeners.
Surfactant selection is important in washing. As with
dyeing, print fixation conditions should be adjusted to
reduce washoff.
4.11.4.15 Emerging Technologies
Several emerging technologies should be considered.
These technologies are not yet commercially available
but might become important in the future. Printers
should stay abreast of:
Fabric scraps and
trimmings
VOCs
BOD/COD and sus-
pended solids
Packaging
Formaldehyde vapors
Toxics
alternatives; avoid fabric
distortions in handling;
use low add-on methods
(e.g., foam, spray)
Pay better attention to
width control to reduce
the need for salvage
trimming; train workers;
establish goals; assign
individual responsibility;
ensure seams are sewn
straight in previous
processes; collect salvage
trim for resale
Minimize volatile chemical
use in finishes
Avoid mix discards; use
automated chemical
feeds; train workers and
mix kitchen design
Purchase chemicals in
bulk or IBCs
Use nonchemical
methods of stabilizing
fabrics; design fabrics not
to shrink; use optimum
catalyst and curing
conditions; use chemical
alternatives
Use special process
alternatives for
mothproofing wool and for
applying special finishes
(e.g., antiodor,
mildewproof)
An endless array of textile products is manufactured
from a limited list of perhaps 10 to 20 basic raw fiber
types. In many cases, the fiber itself (or the structure of
the fabric) cannot provide all the properties that an end-
product requires. To provide these properties, most fab-
rics undergo one or more finishing processes. Finishing
improves or modifies fabrics, enhancing properties such
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as aesthetics, performance, durability, and resistance to
insects/molds/fungi, as well as improving fabric safety
to protect the user (e.g., flame retardancy). Through the
application of needle lubricants, anticurl, and other
agents, finishing can also fine tune the attributes of
fabrics to facilitate cut and sew operations.
Finishing involves chemical and mechanical processes.
In some cases, the finisher can choose between chemi-
cal and mechanical finishing, achieving the same objec-
tive in either case. The types of pollutants associated
with finishing operations and the pollution prevention
approaches available for reducing these pollutants are
described below.
4.12.1 Types of Pollutants
Finishing operations generate solid and liquid wastes,
as well as atmospheric pollutants. Pollutant categories
include:
* Solid wastes: Fabric scraps and trimmings from sel-
vages and seams; fiber dust and fragments from nap-
ping, shearing, and related operations; paper tubes;
and empty chemical drums.
• Liquids: Discarded finishing mixes and rinsewater
from finishing implements and equipment, as well as
facility cleanup.
• Vapors: Exhaust gases from drying and curing.
4.12.2 Pollution Prevention for Major Waste
Categories
4.12.2.1 Solid Wastes
Finish operations generate solid waste in the form of
selvage and seam trimmings, which can be sold as raw
materials for braided rugs or for other craft-related ac-
tivities. For maximum pollution prevention, mills should
collect these wastes in an organized fashion to facilitate
recycling or reuse. Many mills use traversing windups to
form neat rolls of selvage trimmings approximately 20
inches long and 20 inches in diameter. When collected
in this manner, selvage trimmings have high resale
value. An inferior practice is simply to stuff selvage
trimmings in clear plastic bags. The selvage trimmings
become tangled in the bags and then must be untan-
gled, making reuse much more labor intensive. The end
result is that the selvage trimmings lose much of their
resale value.
Seam trimming involves cutting 1 to 5 yards of cloth
near the seam, or up to 5 percent of the total fabric
piece. Excess yarn and fabric generated from cutout
seams should be reduced wherever possible to lower
material costs and reduce waste. An audit can deter-
mine which operations generate the most waste. For
example, the straightness of the seams sewn by the
operator is a major factor in the amount of waste gener-
ated. Straighter seam sewing can reduce the amount of
fabric that must be cut away to remove creases, dye
streaks, and clip or pin outs, to ensure a fabric of even
width, and to prevent shrinkage.
In the worst case, QC samples may be cut from the end
of the fabric piece near a bad seam. Although such
samples are not representative of the entire piece, tests
based on these samples may cause rejection of the
entire piece if the tests indicate a local defect caused by
poor sewing. If this occurs, the entire piece must be
reworked, generating additional pollution and costs. .
The keys to reducing waste caused by bad seams are
training and retraining of workers, using good sewing
equipment (and maintaining it properly), and auditing
seam quality. In a good operation, as little as 0.2 percent
of the cloth is cut out as seams, while in the worst-case
scenario, a loss of as much as 5 percent can occur. To
help monitor seam quality, many mills use different-col-
ored threads in each department. Bad seams then can
be traced by the color of the thread to the department
where they occurred, and corrective action can be
taken. Seam quality also can be improved by requiring
workers to place seam cutouts in specially marked
waste cans. Segregating cutouts facilitates audits and
promotes easier recycling.
Paper tubes often are used to roll up fabric. These tubes
can be reused many times before they become dam-
aged. If they are damaged on one end only (as com-
monly occurs), the damaged end can be trimmed off and
the remainder of the tube can still be used. In many
mills, tube salvage is contracted out to local sheltered
workshops. With knit goods, tubes can be avoided alto-
gether by folding the pieces of the knit goods flat. Some
mills have eliminated the use of paper tubes completely
and instead use PVC pipe. Although costs are initially
higher, the PVC pipe has a long lifetime.
Drums also are a major component of the mill's solid
waste stream. The use of drums is covered thoroughly
in Section 1.2.3, "Solid Waste," but several considera-
tions in drum use are specific to finishing. Returnable
IBCs should be requested wherever possible instead of
standard drums because IBCs significantly reduce the
amount of solid waste. If standard drums are used, they
should be returned whenever possible; the return policy
should permit unwashed drums to be returned. Rinse-
water from drum cleaning can be a major source of
water pollution.
4.12.2.2 Liquid Wastes
Liquid wastes from finishing operations include discarded
mixes and rinses from cleanup activities. Both types of
waste can be reduced using general pollution preven-
tion techniques. Good pollution prevention practice, for
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example, calls for accurate calculation and makeup of
mix quantities to minimize discards (46); the use of auto-
mated mix kitchens to minimize discards was discussed in
Sections 4.11, "Printing," and 1.3.2, "Equipment." Auto-
mated mix systems can automatically meter, dispense,
and mix finish recipes in the necessary quantity. Be-
cause the system can prepare small quantities of mix
quickly and accurately, the mixer has no reason to prepare
excess amounts of finish, which usually are discarded.
Onsite drum washing can add large volumes of contami-
nated wastewater to the waste stream and should be
eliminated. Many mills have removed drum washers
from operation for this reason. More importantly, bulk
delivery tanker trucks should never be washed out at the
plant site. Some truck drivers try to avoid cleaning costs
by washing out their trucks at the plant site and pouring
washwater into the plant's waste system or (even worse)
into parking lot drains.
4.12.2.3 Atmospheric Emissions
As described in Section 2.2.3, "Toxic Air Emissions,"
many pollutants have been detected in air emissions
from textile mills. Sources include:
• Dryers
• Curing ovens
• Steaming operations: knits (calendaring)
• Ventilation from mix kitchens
• Bulk storage tanks: breathing losses and spills
• Chemical warehouses
Table 4-53 lists some observed air pollutants from fin-
ishing, along with typical sources. These can be mini-
mized by:
• Avoiding the need for chemical finishes (discussed
below).
• Properly controlling air circulation and temperature in
dryers (see Section 1.3.2, "Equipment").
4.12.3 Pollution Prevention for Fabrics Other
Than Wool
Finishing of cotton, cellulosic, and synthetic fibers in-
volves a variety of chemical and physical processes,
which can generate pollution. The sections below iden-
tify general and specific pollution prevention strategies
that can be applied to finishing operations.
4.12.3.1 Chemical Finishing Alternatives
Typical finishing recipes for cotton and cotton blends call
for a combination of the following:
Table 4-53. Pollutants Detected in Textile Mill Air Emissions
(11)
Pollutant
Possible Source(s)
Acetic acid
Acrylic monomers
Biphenyl
Carbon monoxide
Dibutyl phthalate
Ethylene oxide
Formaldehyde
Glycol ethers
Hexane
Hydrocarbons
Hydrogen chloride
Methanol
Methyl ethyl ketone
Methyl methacrylate
Methylene chloride
Perchloroethylene
Toluene
Trichloroethane
Vinyl acetate
Xylene
Residue from dyeing or printing
Residue from handbuilder
Residue from dye carrier
Incomplete oxidation of fuel
Residue from dye carrier
Breakdown of wetting agent
Breakdown of cross-linking resin
Softeners
Softeners, wax water repellent
Softeners, wax water repellent, spin finish
residues, knitting/winding lubricants
Chloride catalyst, machine cleaner,
reduction of chlorinated organic residues
from dyeing in recycle air, in reducing
atmosphere, in heater flames of drying
and curing ovens
Cross-linking reaction product, wetter
Machine cleaning solvent
Handbuilder impurity
Machine cleaning solvent
Machine cleaning solvent, dye residue
Machine cleaning solvent
Machine cleaning solvent, spot remover
Handbuilder impurity
Machine cleaning solvent, dye residue
• Cross-linking resin and its required catalyst.
• Softener.
• Wetting or penetrating agent.
• Sewing lubricant.
• Handbuilder (stiffener).
• Functional additives (e.g., water repellent, flame re-
tardant).
If the fabric does not contain cotton (or other cellulose
fibers), a resin and catalyst are not necessary. Many
chemical and mechanical alternatives are available for
every type of finishing operation. These alternatives are
listed in the annual AATCC Buyer's Guide (19). Although
discussing the pollution prevention advantages and dis-
advantages of each of these alternatives is impossible,
the following paragraphs present some general and
specific strategies for selecting appropriate alternatives
to maximize pollution prevention.
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General Strategies
• Proper fabric design: Fabric should be designed to
meet end-use requirements with minimal finishing
(20, 82), including selecting the correct fiber (e.g.,
cotton, polyester), yarn count and form (e.g., ring
spun, rotor spun, filament), and fabric structure (e.g.,
knit woven, nonwoven, braided). Most finish proper-
ties (e.g., antisoil) can be achieved with proper fabric
design (20). Table 4-54 contains some examples of
mechanical finishes or design choices that can re-
duce the need for chemical processing. Textile fabric
design is primarily driven by considerations of color,
artistic design, and aesthetics. Designs based on en-
gineering and chemical principles can eliminate the
need for finishing and reduce waste, but designers
rarely incorporate those principles into their designs
(20). The environmental impact of product specifica-
tions also should be considered. Table 4-55 shows
softener alternatives and their environmental im-
pacts. Vertical manufacturing operations (those that
include cut and sew operations in the finishing proc-
ess) enable designers to specify a greater variety of
fabric structures and construction than commission
finishing operations. Because designers are closer to
the customer, they also have an opportunity to work
with the customer and convey information about the
environmental consequences of design and color al-
ternatives.
Tablo 4-54. Examples of Mechanical Finishes and Design
Alternatives That Avoid Chemical Processing (20)
Desired
End-Use
Property
Mechanical Finish or Design Alternative
(Nonchemical)
Soil release
Shrinkage control
Cotton knit
Synthetic
Softness
Bulk/stiffness
Use cotton; will not retain oily stains
Design fabric with proper width and yield; use
"compactor" (see Section 1.3.2, "Equipment");
handle only when relaxed
Heatset fabric (no resin required)
Use bulkier yams
Use looser knit or weave
Use enzyme softening of cotton
Use mechanical calandar (wovens only)
Use napping, shearing, sueding, sanding, etc.
Use higher twist "hard" yarn
Use tight construction
Proper fabric handling: After establishing a design
specification, proper fabric handling can reduce the
need for further processing, in particular, knit fabrics
should be handled with minimum tension to avoid
stretching the fabric, which can result in shrinkage or
require later stabilization with resin to avoid shrinkage
(82).
• Consideration of mechanical alternatives first: If fabric
design and handling issues have been addressed
and further finishing is still required, mechanical al-
ternatives should be considered before selecting
chemical finishing. One major purpose of finishes is
to stabilize fabrics and reduce shrinkage, but heat-
setting (thermosetting) of synthetic fabrics or com-
pacting of cotton fabrics will also suffice for this
purpose.
• Optimization of chemical finishing processes: After
deciding to use chemical finishing, finish application
and processing should be optimized to avoid gener-
ating more waste than is necessary. Each greige style
should be treated with an optimum recipe to produce
the desired end properties.
Table 4-55. Types of Softeners Used in Textiles and Their
Environmental Considerations (83)
Material
Type
Environmental
Consideration(s)
Fatty materials Anionic
Cationic
(quaternary)
Petrochemical Hydrocarbon
materials
Alkene oxides
Polyethylene
Silicone
Reactive
Nonreactive
Biodegradable; some methods
of production use metal
catalyst, thus may result in
residual metal impurities
High aquatic toxicity
Produce hydrocarbon
emissions from drying and
curing ovens
Can contain volatile ethylene
oxide impurity, which may
vaporize from dryers
Nonbiodegradable; can
produce hydrocarbon
emissions from drying and
curing ovens
Durable
Nondurable
Specific Strategies
In addition to these general principles for avoiding or
minimizing chemical use, recommendations can be
made for reducing or eliminating many specific chemi-
cals used in finishing cotton and blends.
Formaldehyde-containing resins used for permanent
press finishing. Cotton, rayon, and other forms of cellu-
lose and blends that contain these fibers usually require
finishing with a reactive agent to cross-link adjacent
cellulose chains. This step immobilizes the fibers, reduc-
ing shrinkage and improving bending properties (i.e.,
crease recovery). Many types of reactive cross-linkers
exist. Currently, the products of choice for cross-linking
cellulose are N-methylol compounds, which are pro-
duced from reacting urea with formaldehyde and other
202
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additives. In application and use, these reactive N-
methylol cross-linkers can release formaldehyde.
The issue of formaldehyde emissions from textiles has
received considerable publicity. Formaldehyde, which is
connected to cancer in animals, is a cross-linker. Other
low-molecular-weight cross-linking agents also can be
carcinogenic, however. For that reason, an efficient al-
ternative that is not carcinogenic, mutagenic, or terato-
genic is unlikely to be found for cross-linking agents. The
most widely used cross-linking agent is dimethylol dihy-
droxy ethylene urea (DMDHEU). This eigent usually re-
acts with cellulose under high temperatures in the
presence of a catalyst such as magnesium chloride.
When properly used, applied, and cured, formaldehyde
releases from fabrics treated with DMDHEU are mini-
mal. Generalizing about personnel exposure to formal-
dehyde in fabrics is difficult because the amount of
airborne formaldehyde that fabrics release varies
greatly depending on temperature, humidity, ventilation,
and other factors (84).
A few nonformaldehyde cross-linkers are used commer-
cially (usually as a research experiment at the mill level).
These cross-linkers are considerably more expensive
than DMDHEU and, therefore, have never been used
widely in the U.S. textile industry. They include butane
tetra carboxylic acid (BTCA) and dimethyl dihydroxy
ethylene urea (DMeDHEU). Although neither agent con-
tains formaldehyde, their performance is inferior to that
of DMDHEU.
Pollution prevention strategies for formaldehyde reduc-
tion are highlighted below:
• Fabric designers should use fibers and construction
techniques that require few, if any, cross-linkers.
• Fabrics should be handled properly to avoid shrink-
age during processing.
• Handbuilders and dye fixatives, if used, should con-
tain low or no formaldehyde (see below).
• When applying resins, low-formaldehyde versions of
DMDHEU should be selected wherever possible. The
resins should be applied under optimum conditions,
including providing for proper finish penetration be-
fore curing. The use of efficient catalysts minimizes
resin carryover. Finally, finished fabrics should be
cured under proper time/temperature conditions.
• The fabric should be washed after curing to remove
the catalyst, reducing the potential for formaldehyde
release. (The crosslinking curing reaction is easily
reversed in the presence of the catalyst.)
• Once finished, fabrics should be stored in well-venti-
lated areas away from formaldehyde sources.
Softeners. A wide variety of softeners exist, including
natural and synthetic compounds (24). The main types
of softeners are fat, petrochemical, and sificon based
(25). The environmental considerations of each type are
listed in Table 4-55. Finish recipes, which include soften-
ers, often are made up the same way they were many
years ago, without regard for environmental considera-
tions (22, 23).
The performance and environmental impacts of each
type of softener vary, and each type has advantages and
disadvantages (24, 25). Fatty acid softeners are very
biodegradable (24), while both paraffin and polyethylene
softeners are nonbiodegradable (24). Quaternary types
have high aquatic toxicity (24). Mineral oil and paraffin
wax softeners are still used, although these types of
softeners smoke when heated, producing air emissions
from dryers (22, 23). Polyethylene glycol (PEG) and
polyethylene oxide (PO), on the other hand, are non-
smoking alternatives. Reactive silicone softeners are
well fixed and do not wash off of the fiber, whereas most
other types wash off during home laundering of the
textile products (24).
In some cases, cellulase enzymes can remove surface
roughness in yarns and fabrics, creating smoothness
and lubricity without the use of chemical additives (24).
Certain types of yarn (i.e., ring spun yarns) are inher-
ently softer, while rotor spun yarns are "scratchy" and
require more softeners to provide comfort for apparel
end-uses. For maximum pollution prevention, opportu-
nities for using nonchemical alternatives should be fur-
ther investigated.
Builders. One class of functional materials applied to
fabrics is builders or handbuilders. For many applica-
tions (e.g., men's suits), a fabric must have "body" or
stiffness. In lightweight fabrics, this body or stiffness can
be provided by using builders or handbuilders. These
agents increase the bulk of the fabric and, sometimes,
the bending or rigidity of the fabric. Generally, builders
or handbuilders are film-forming agents that might or
might not react with the fabric. Builders include (25):
• N-methylol film-forming materials (reactive):
- Trimethylol melamine
- Urea formaldehyde
• Natural polymers (nonreactive):
- Starches
— Modified starches
- Alginates, gums, etc.
• Synthetic polymers (nonreactive):
— Polyvinyl alcohol
- Poly acrylates (acrylic, vinyl)
Acrylic handbuilders and stiffeners can replace formal-
dehyde-based N-methylol handbuilders (22, 23). Acryl-
ics are good substitutes in many applications, but the
203
-------
use of acrylate monomers, and especially their manu-
facture, is linked to other pollution problems.9 The algi-
nates, starches, and modified starches are the least
harmful environmentally, but they also have high BOD.
The reactive types give a distinctive "bounce" or lively
feel to the cloth, whereas the nonreactive types often
feel "dead" or "cakey."
Functional materials. The above sections cover the
most commonly used finishing agents. In addition, a
wide variety of other functional finishes is also used. The
environmental impacts of these finishes vary greatly,
however, and substitution possibilities are explored in
more detail elsewhere (e.g., Lewin and Sello [85]). The
extent to which individual functional finishes contribute
to pollution in textile operations is described further in
sections covering generation of particular pollutants. For
example, antiodor finishes based on metals are dis-
cussed in Section 2.2.5, "Metals."
Finishing equipment. Finishing equipment should be de-
signed, selected, and maintained to minimize pollution.
Major considerations include design and maintenance
of dryer air systems and finishing ranges, use of low
add-on finishing recipes, proper control of curing condi-
tions, and general system maintenance (see also Sec-
tion 1.3.2, "Equipment").
Air distribution systems in dryers should be clean with
no leaks or distorted exit/pickup orifices to reduce flows
(54). Makeup air needs to be well balanced, both in
terms of intake and exhaust flows as well as end-to-end,
side-to-side, and top-to-bottom within the dryer. Hot air
ports should be located or moved as close to the fabric
drying line as possible to reduce energy requirements
and to lower air emissions.
Low add-on finishing results in less air volume discharge
and lower energy use and, consequently, reduced boiler
emissions (54). Low add-on finishing is discussed in
more detail below and in Sections 3.6, "High-Extraction,
Low-Carryover Process Step Separations," and 3.19,
"Pollution Prevention Through New Equipment."
Proper humidity and temperature control in drying and
curing ovens can ensure maximum reaction and mini-
mum emissions from drying, curing, or later processing.
Automatic humidity sensors often are used along with
real-time airflow and damper controls to maintain nearly
ideal drying and curing conditions at all times. For ex-
ample, in drying, about 50 to 60 percent relative humidity
is optimum for many fabrics. Optimum curing conditions
depend on the fiber, reactant, and catalyst involved and
should be investigated as part of the pollution prevention
strategy.
9 Aorylata ts synthesized from materials such as methyl methacrylate
monomer. These materials are polymerized with a free radical
mechanism that results in leftover monomer. AH of the monomers
are toxte and carcinogenic and, therefore, undesirable.
Other considerations for preventing pollution in finishing
include:
• Performing regular maintenance of finishing equip-
ment to ensure that optimum finishing conditions pre-
vail at all times.
• Designing plumbing runs from the mix kitchen to the
finishing ranges to be as short as practical to mini-
mize the amount of mixes dumped from the finish
distribution lines at the end of a run.
• Auditing pad troughs and chemical feed lines for
leaks. Inspection and maintenance routines should
be established to minimize the amount of time re-
quired to respond to leaks.
4.12.3.2 Mechanical Finishing as an Alternative
to Chemicals
Mechanical finishing can impart a wide variety of end-
use properties. Table 4-54 contains an abbreviated list;
a complete analysis would be beyond the scope of this
document because dozens of mechanical finishing
processes currently exist. Mechanical finishing gener-
ates less pollution than chemical finishing because it
involves no:
• Mix discards
• Pads to dump
• Chemically contaminated machines to clean
• Chemical residues to release in storage and use
• Obsolete chemicals to dispose of
• Drums to wash and recycle
• Finish components vaporizing in dryers
• Breathing or spill losses from bulk tanks
Mechanical finishing has several advantages, most im-
portantly that it does not use chemicals (although fiber
lubricants may at times be required for certain proc-
esses, such as napping). By avoiding the use of reactive
chemistry, dyed shades are not changed during the
finishing process (i.e., no shade breaks). In addition,
because mechanical finishing does not subject dyes to
reactive chemicals or to the conditions of pH and heat
that are necessary for chemical finishing, the result is
less off-shade work and associated redyes.
Some of the most popular fabrics today are cotton and
cotton blend knits, and these fabrics often require
chemical resin stabilization for shrinkage control and
sewability (82). Stabilization of these knits is possible
without the use of chemical additives, however. The two
keys to accomplishing this are to (82):
204
-------
• Ensure that the equilibrium relaxed configuration of
the knit fabric is exactly equal to the customer speci-
fication in terms of width, yield (weight), and shrinkage.
• Design a process that allows for complete relaxation
of the fabric.
Commercially available computer-assisted design pro-
grams allow the finisher to select the correct yarn, ten-
sion, stitch length, machine cut, and diameter for making
knit goods with the proper width, yield, and shrinkage
(82). A key to computer-assisted design is to keep the
processing step as tensionless and consistent as possi-
ble. Commercial knit finishing equipment (e.g., compac-
tors, dryers) is available that can control the width and
length of the fabric during processing, allowing the knit
to fully relax. The operation of these machines is docu-
mented in the literature (82). Design factors and knitting
machine setup requirements also are available (82).
Specifications for knit fabric width and yield must be
compatible with the relax dimensions of the greige
goods (82).
4.12.3.3 Novel Finishing Practices
Low add-on finishing conserves energy and reduces
pollution because fewer chemicals are needed for a
given level of performance (84). Low add-on finishing
also can prevent leaching or transport of chemicals from
the interior of fibers to the surface, which can occur with
high add-on methods, thus improving fastness, shade
change, and softness of finished goods. In addition,
these finishes accelerate production (84). The effective-
ness of low add-on finishes depends on finish penetra-
tion of the fabric during the lowest possible wet pickup
(WPU) (84). Table 4-56 describes some low add-on
finishing techniques.
Table 4-56. Commercial Low Add-On Finishing
Processes (84)
Process
Air-jet pad
Curved blade applicator
Fabric-transfer loop
Gas phase
High extraction pad
Kiss roll
Printing
Spray
Stable foam
Unstable foam
Vacuum systems
Wicking systems
Application
Saturation/expression
Controlled application
Combination
Controlled application
Saturation/expression
Controlled application
Controlled application
Controlled application
Controlled application
Controlled application
Saturation/expression
Controlled application
Because less water is used with low add-on finishes, the
chemicals (if properly applied) are more evenly distrib-
uted throughout the fabric, resulting in more efficient
fabric stabilization. Evaporation and drying occurs only
on the surface of the yarn. When moisture add-on is
high, however, moisture flows from the inside of the yarn
to the surface, transporting chemicals to the surface.
Surfacing of the chemicals causes uneven treatment of
the yarn, requiring greater chemical add-on to obtain the
same performance. The best finish distribution (i.e., the
optimum performance obtained with the least amount of
chemical add-on) is obtained by lowering the WPU level
to a minimum level that will fully wet the fabric (approxi-
mately 45 percent for cotton and blends in most cases)
and by keeping the temperature low in the dryer.
Smith (84) presented a test methodology that can be
used to assess the optimum WPU ratio required to
ensure minimum unevenness of finish distribution. Table
4-57 presents laboratory results for various types of
cotton fabrics.
4.12.3.4 Foam
Foam technology is used for applying stain release
chemicals to carpets. Liquid solutions normally used for
treatment often are replaced by foams, which lowers
WPU to as little as 8 percent (86). The minimum WPU
level for good finish penetration on cotton and cotton
blends normally is approximately 45 percent (84). For
example, one plant that adopted foam technology re-
portedly reduced water use by 20 million liters per year.
The same plant cut energy use by 10 percent overall (86).
For a surface finish on a synthetic fiber as described in
Powell (86), the appropriate WPU is much lower than
the 45 percent determined for cotton, which is more
Table 4-57. Optimum Wet Pickup Levels for Various Cotton
Fabrics (84)
Fabric (100% Cotton)
Optimum Wet Pickup (%)
5.5 oz/yd printcloth
Bleached
Mercerized
36
41
5.5 oz/ydz printcloth, 60 minutes dwell time before cure
Bleached 22
Mercerized . 20
5.5 oz/yd2 printcloth, 5 seconds steam before cure
Bleached 13
Mercerized 13
5.5 oz/yd2 poplin
Bleached 31
Mercerized 33
5.5 oz/yd2 drill
Bleached 45
Mercerized 43
205
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absorbent than synthetic fibers (84). A further benefit of
low add-on techniques is that less water must be evapo-
rated from the fabric, resulting in energy savings.
Foam, however, can be difficult to handle in actual pro-
duction situations. Foams are quite different from liquid
finishes and tend to collapse when pumped through
constricted pipes and T-joints, or around sharp bends,
comers, and elbows. They are difficult to form and to
keep stabilized; foams require some running time to
stabilize, so whenever the production line stops, foam
must continue to be generated to avoid long startup
delays. During stopoff, therefore, foam must be sent to
waste, creating floating solids in waste treatment sys-
tems, as well as bulking of clarifiers and other opera-
tional difficulties. Careful planning and engineering can
minimize the problems associated with foams, but can-
not eliminate them.
4.12.3.5 Spray
Softeners and other surface finishes can be added by
oversprays and other techniques with inherently low
add-on. Because of the lower add-on, these methods
require no dumping of residual pad liquors at the end of
a run. Spray applications should be investigated as part
of pollution prevention planning.
4.12.3.6 Mix Kitchens and Mixing Practices
In finishing, more padding liquor often is prepared than
needed for the lot being run (60). Preparing more mate-
rial than is needed, or overmixing, is one of the main
sources of pollution in textile manufacturing not only in
finishing, but also in printing and continuous dyeing
operations.
Overmixing is done for one of two reasons. First, em-
ployees mix excessive amounts of material such as
finish to avoid having to make up a second mix to finish
off a lot. When the lot is completed, the excess finish is
dumped. In many cases, however, overmixing occurs
because equipment is not designed to mix less than
complete batches. Mix tanks, for example, commonly
lack volume marking; therefore, the only way to make a
mix properly is to make a full tank (normally 200 gal-
Ions). A mill might even make up a 200-gallon mix to run
a 100-yard sample lot. The sample lot consumes per-
haps only 10 to 15 gallons of mix, and the remaining 185
to 190 gallons are dumped into the waste treatment
system.
Such flagrant waste can be avoided with new or modi-
fied systems or by simply improving mixing procedures.
The best pollution prevention practice is to use auto-
matic chemical dispensing in the mix tanks. If mixes are
made manually, only the minimum amount required for
the tot should be prepared. All mix tanks should be
equipped with volume markers that allow the makeup of
mixes in any amount. Because most mix tanks hold 200
gallons, the mix operator must be able to see marks on
the inside of the tank to measure out any volume other
than 200 gallons. In the case of leftover mixes, additions
to the leftovers should be made whenever possible to
produce new mixes. The calculations are relatively
straightforward, as shown in the sample below:
1. Two hundred gallons of 6-percent softener solution
is made up using 100 pounds of softener diluted to
200 gallons.
2. The lot uses 145 gallons, and 55 gallons are left over.
3. The next lot calls for 100 gallons of 4-percent sof-
tener mix.
4. One option (i.e., the one that is most often chosen)
is to dump the leftover 55 gallons of mix containing
27.5 pounds (55 x 8.34 x 0.06) of softener and make
up a new mix with 33.4 pounds (100 x 8.34 x 0.04)
of softener in 100 gallons of water. (Note: One gallon
of water weighs 8.34 pounds.)
5. A better way is to add 5.9 pounds (33.4 - 27.5) of
softener to the leftover 55 gallons, and add water to
100 gallons. Adding softener and water to the mix
avoids waste, reducing pollution and costs.
Scheduling makeup of similar mixes in sequence is
helpful in preparing new mixes from leftover materials.
Also, worker training is needed for performing the cal-
culations shown.
Scheduling also is important in minimizing cleanup.
Each worker should be familiar with dry capture of
spilled chemicals using scoops, squeegees, or vacuums
(rather than washing chemicals down the drain with a
hose). Proper vacuums or other equipment must be
available in the mix area. Implement washing should be
minimized whenever possible. The preferred methods of
chemical handling are direct chemical dispensing or
IBCs. If manual methods and drum storage are used, a
separate dipper for each chemical should be available,
eliminating the need for continuous washing of dippers
and buckets.
4.12.4 Pollution Prevention Practices for
Wool Finishing
Pollution is a concern in several areas of wool finishing.
A recent study by the International Wool Secretariat
(IWS) identified four high priority areas (7):
• Pesticide residues in wastewater from chemicals ap-
plied to sheep.
• Discharge of mothproofing agents from wool carpet
manufacture.
• Emissions of halo-organics from wool shrinkproofing.
• Chromium releases from chrome dyeing operations.
206
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The following areas are being regulated to reduce
aquatic toxicity from wool operations (3, 7, 87-89):
• Agricultural residues: The main concern in this area is
pentachlorophenol insecticides used on sheep (3).,
An alternative is to use less-toxic insecticides. Substi-
tuting a less toxic insecticide for a more toxic one is an
example of a pollution prevention strategy that must
transcend production boundaries because the problem
originates in upstream operations (i.e., farms) but does
not become apparent until the wool is washed at the
mill. Sheep ranchers must be educated to understand
the problems of using toxic insecticides.
• Mothproofers: Resistance to insects, or mothproof-
ing, traditionally has used chemicals that, because of
increasing regulation, are no longer acceptable (87,
88). These changes especially affect the carpet in-
dustry, where mothproofing of wool fabric is an im-
portant finishing step. The usual mothproofing
procedure requires permethrin, a chemical that now
is strictly controlled in many parts of the world. Al-
though permethrin is reportedly biodegradable and
has low mammal toxicity (humans), it has high
aquatic toxicity (87). Mothproofing of wool is per-
formed most often by adding chemicals to the dye-
bath, which then exhaust onto the wool (87, 90). The
spent dyebaths, when discarded, can cause aquatic
toxicity (87, 90).
Several chemical alternatives for mothproofing have
been reported, including:
• Clorphenylid: Was used widely but now has been
withdrawn because of environmental problems gen-
erated during its manufacture.
• Flucofuron: Not fully evaluated at this time but is
known to be ineffective against certain pests. Evalu-
ations are still underway.
• Cycloprothrin: Has good performance with an aquatic
toxicity rating that is approximately three orders of
magnitude less than that of permethrin (90).
• Diphenylurea: Has lower aquatic toxicity than per-
methrin but is less biodegradable (87).
• Cyfluthrin: Effective but has been withdrawn because of
reactions by textile mill workers to the chemical
(87, 89).
• Sulcofuron: Shows low affinity in some application
methods and is ineffective against certain pests (89).
European Community directives on aquatic pollution
from mothproofing agents are shown in Table 4-58.
Leftover portions of wool processing baths are some-
times discharged, contributing to pollution problems
(87). Commercial solutions are typically applied with
exhaust and continuous (e.g., spray) processes (87).
Table 4-58. European Community Directives on Aquatic
Pollution From Mothproofing Agents Used for
Wool (9)
Active
Ingredient
Chlprphenylid
Cyfluthrin
Sulcofuron
Flucofuron
Permithrin
Mothproofing
Agents
Eulan WA New
Eulan SP
Mitin FF h.c.
Mitin N
Eulan SPN
Eulan WP
Mitin BC
Perigen
SMA-V
EQS
Monograms/Liter
of Active
Ingredient
50
1
25,000
1,000
10
The discharges of mothproofing agents from finishing
operations can be reduced, but they can never be com-
pletely eliminated as long as mothproofing agents are
used (87). Treatment of spent (or leftover) wool finishing
baths with alkali hydrolyzes toxic chemical contents.
The amount of mothproofing agent used should be con-
trolled carefully to produce the desired result with the
least amount of application. Another alternative that cur-
rently is under investigation is nitromethylene. Studies
on mixtures of nitromethylene and permethrin show
promise and are continuing (87). Because of regulations
prohibiting certain mothproofing agents and other limita-
tions cited above, the only other alternative is a
pyrthroid-based insecticide (7).
Other possibilities for reducing pollution from moth-
proofing operations include:
• New application methods involving microemulsion
spray/centrifuge techniques along with recycling of
pesticide solutions (see Figure 4-20 and Table 4-59)
(7, 87).
Yarn Hanks
Pump
Two-Way Valve 1
To Waste
Figure 4-20. Modifications to a centrifuge (hydroextractor) for
application of mothproofing agent solution (7).
207
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Table 4-59. Use of Spray/Centrifuge Techniques To Reduce
Discharges of Permethrin (7)
Permethrin
Concentration Permethrin
(mg/L) in Load
Effective Spent (g/tonne of
Liquor Treatment wool
Method Ratio Bath treated)
Hank dyebath
Conventional tape scour
Minibowl tape scour
Modified centrifuge
50:1
0.75:1
0.1:1
0.05:1
0.16
40
40
34
8
30
4
1.7
• New pesticides with low aquatic toxicity.
• Nonpesticide mothproofing methods.
The use of microemulsion spray/centrifuge techniques can
reduce discharges of permethrin to as low as 1.7 grams of
permethrin per tonne of wool treated, compared with 8.0
grams of permethrin for conventional hank treatments in
dyebaths (7). The length of treatment controls the add-on
level in the centrifuge technique (88). The evenness of
treatment is commercially acceptable, provided that the
emulsion is prepared properly and the temperature is con-
trolled (88). The emulsion, which drains from the extractor,
is reused. Water use is reduced from 0.75 liters per kilo-
gram (90 gallons per 1,000 pounds) of wool to 0.06 liters
per kilogram (7.2 gallons per 1,000 pounds) (88). The best
pollution prevention strategy is site-specific based on the
properties of the agents involved.
One mill developed the following strategy for reducing
wastewater toxicity based on presently available moth-
proofing agents (89):
• Use sulcofuron as much as possible (but this agent
has performance limitations).
• Use flucofuron to the extent permitted by the waste-
water regulations.
• Use permethrin (or cyfluthrin if still permitted) for the
balance of production.
The results of such a strategy are shown in Figure 4-21.
A second mill used similar logic but arrived at a different
strategy because of different processing practices (89).
In this mill, the strategy was to:
• Discontinue mothproofing as part of the scouring process.
• Use permethrin to the extent permitted (because of
marketing demands).
• Use flucofuron to its limit after reaching the per-
methrin limit.
• Use sulcofuron for the remaining production.
Sulcofuron
0.7 Mkg/year
L
Flucofuron
1 .7 Mkg/year
>
f
Permethrin
10.8 Mkg/year
Application to Fiber
Exhaustion =
90%
90%
92%
<
River High Flow
Stour Low Flow
EQS
4
1 ,200 g/day
4
4
750 g/day
4
4
400 g/day
4
Sewage Treatment Works
Removal =
80%
4
240 g/day
4
380 ng/L
1,600ng/L
25,000 ng/L
80%*
4
150 g/day
I
230 ng/L
1 ,000 ng/L
1 ,000 ng/L
95%
4
20 g/day
4
31 ng/L
133 ng/L
10 ng/L
* Estimated
Figure 4-21. Implementation of "best" mothproofing strategy
by carpet industry in Kidderminster, United
Kingdom (89).
These reduction strategies suggest the need for new non-
polluting mothproofing systems based on zero-pollution
discharge application methods for existing chemicals,
chemical agents that are safe, or nonchemical mothproofing
agents. Zero-pollution discharge application methods in-
clude the use of low liquor ratios, microemulsions, accurate
metering to ensure the minimum necessary amount of agent
is used, and better process controls (89). Research contin-
ues on these alternatives, and promising developments are
underway (89).
Wastewater from wool shrinkproofing contains halogen-
ated organics. These chemicals appear in drinking water
supplies as absorbable organic halogens (AOX) (7).
Figure 4-22 presents AOX loads from steps in the wool
shrinkproofing process in grams of AOX per tonne proc-
essed, as well as in ppm in the effluent (7). Aggregate
discharge of chlorine in shrinkproofing is 39 ppm, which
is far above the proposed regulatory limit of 1 ppm. Re-
search is underway to develop nonchlorine shrinkproof-
ing methods, but no successes have been reported (7).
4.13 Cutting, Sewing, and Product
Fabrication
The following table introduces the pollutants and waste
streams discussed in this section, as well as suggested
pollution prevention activities for each.
208
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Numerous factors affect the amount of waste generated
in cutting, sewing, and product fabriceition operations,
including pattern layout efficiency and the level of exper-
tise of cutting and sewing operators. The level of waste
is also a function of design and planning decisions,
information flow, and communication. This section dis-
cusses the essential elements of a plan to minimize
waste from cutting and sewing operations, as well as
ways to reuse and obtain value from waste.
Pollutant or Waste
Stream
Pollution Prevention
Actions Described
in This Section
Comments
4.13, Cutting, Sewing, and Product Fabrication
Fabric scraps Pattern marker
optimization
Reuse of cutting
room fibers
Postconsumer
recycling
4.13.1 Amounts of Waste Generated
Although no published data on cutting room waste are avail-
able, typical levels based on inquiries to cutters in various
types of textile operations are presented in Table 4-60. The
amount of waste varies according to this type of goods
produced. Open width knits (48 to 62 in. double knit/warp
fabrics) usually represent 13 to 16 percent of "shape" or
cutting waste (fabric remnants). In some mills, however, this
represents the highest amount of cut waste generation. At
some facilities, "tubular" knit fabric, which varies in cylinder
sizes (15 to 28 in.), offers the least waste when used in tubular
form to produce tubular garments with no sideseam. Typi-
cally, pattern design provides for shape or cutting waste levels
of approximately 8 percent. This represents an average
covering all basic product types (e.g., sweatshirts, t-shirts).
400
300
200
100
These cutting room efficiency factors can translate into
substantial amounts of waste. In the United States each
year, about 800 million yards of denim are produced, at
an average weight of perhaps 12 ounces per linear yard,
or a total weight of well over one-half billion pounds of
denim. The efficiency for cutting denim is typically 84
percent or less. (In general, fabric utilization efficiency
in cutting and sewing ranges from about 72 percent to
94 percent). Cutting waste therefore represents about
16 percent of denim production, or roughly 100 million
pounds annually in the United States for denim alone.
Similar analyses can be done for each of the other
fabrics presented in Table 4-60.
4.13.2 Pollution Prevention To Reduce
Waste Levels
Pattern marker efficiency is essential to reducing the
amount of cutting room waste but depends strongly on
garment design factors such as shape and seam location,
size assortment as required by retail sales, fabric width,
and other technical considerations. Cutting practices
that minimize waste are well known, and material utili-
zation departments are skilled at optimizing cutting effi-
ciency. Waste minimization in this area is a highly
developed science, and many operations use sophisti-
cated computer algorithms and other techniques. Com-
mercially viable systems probably could not be developed
that would surpass current efforts at minimization of
cutting waste. Improvements could almost certainly be
made through design modifications or better planning
(i.e., coordination between fabric supplier and retailer)
and through process improvements such as use of con-
sistent yarn and fabric weights.
Mills can make advances in the reuse of cutting room
fibers, which could potentially prevent a substantial
amount of pollution. At present, denim cutting waste is
400
300
200
100
Q L- ''"« iiuuiii^^™» mm^ aman^ tttmti^ [^ HHHE^^M^_^ r\
Chlorinalion Antichlorination Neutralization Rinse Resin Softener Total
AOXLoad
(g/tonne wool)
AOX Concentration
(mg/L)
Figure 4-22. AOX loads and concentrations from each of the six bowls of a continuous chlorine/Hercosett plant (7).
209
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Tablo 4-60. Typical Levels of Cutting Room Wastes
Typa of Good
Denim
Knits: open width
Knits: tubular
Woven: other than denim
Typical Waste
Percentage
16%-24%
13%-16%
25%-27%
No consensus
Lowest Waste
Percentage
6%
11%
22%
No consensus
recycled into end-uses such as paper making. The value
of this fiber in such uses, however, is below its value in
denim manufacturing. If manufacturing procedures were
developed to reclaim fiber from denim cutting waste and
reuse it, the cost of the raw fiber would be reduced, and
dyeing requirements (and associated pollution) would
be reduced because the indigo denim color would al-
ready exist in the reclaimed fiber.
In addition to cutting room waste, postconsumer recy-
cling of discarded blue jeans or other denim products
could be combined to use the same technology. One
attractive feature of this opportunity is that it presents
minimal political or business barriers.
4.14 Installation
The following table introduces the pollutants and waste
streams discussed in this section, as well as suggested
pollution prevention activities for each.
Pollutant or
Waste Stream
Pollution Prevention Actions
Described
in This Section
Comments
4.14, Installation
Goneral
Vendor/customer information
exchange; design of textile and also
of composite products; purchasing
specifications; better general
expertise; storage conditions
The manner in which textile materials such as carpet-
ing, wall coverings, and upholstery are installed can
have a considerable impact on their performance.
Poor installation techniques can negatively affect the
lifetime of the product, requirements for aftermarket
treatments, and the quality of indoor air. For example,
if inappropriate adhesives are used to bond textile
coverings (e.g., to ceilings, walls, floors), retention of
solvent odors can produce long-term indoor air pollu-
tion. Consumer actions, such as aftermarket textile
treatment and care, can also affect textile perform-
ance (see Section 4.17, "Consumer Issues and Con-
sumer Care").
Smith and Bristow (83) report that industry working
groups have identified the following as important indoor
air pollution issues to consider when selecting and in-
stalling textile components for indoor use:
• Ageing of products.
• Identification and selection of low emitting products.
• Quantifying indoor air emissions.
• Proper product storage by the installer.
• Effects of adhesives containing VOCs.
• Proper adhesives, eliminating inappropriate adhesives.
• Panels and partitions designed to minimize sorp-
tion/reemission.
• Heating, ventilating, and air-conditioning (HVAC) sys-
tem design, air flow in the room, placement in relation
to emitters.
In many cases, textile material is part of a larger textile-
containing product. Therefore, all components of the prod-
uct must be compatible. For example, storage of textile
materials with solvents or other VOC-emitting materials
can produce contamination that requires time to desorb.
Therefore, a key to preventing pollution is to provide better
information on the textile product, potential incompatible
chemical and mechanical installation procedures, incom-
patible or inappropriate combinations with other materials,
and proper storage conditions. Unfortunately, most textile
sales organizations are not sufficiently well informed about
such technical issues and are thus unable to understand
and communicate the required information. This is an area
that shows a specific need for pollution prevention training
(see Section 5.3, 'Training Programs"). Training programs
designed to educate sales personnel about these issues
should be developed and implemented.
4.15 Aftermarket Treatments
The following table introduces the pollutants and waste
streams discussed in this section, as well as suggested
pollution prevention activities for each.
Pollutant or
Waste Stream
Pollution Prevention Actions
Described in
This Section
Comments
4.15, Aftermarket Treatment
General
Vendor/customer information
exchange; design of textile and also
of composite products; purchasing
specifications; better general
expertise; storage conditions
Aftermarket treatment issues are similar to the instal-
lation information discussed in the previous section
(Section 4.14, "Installation"). The distributor or retailer
may add many topical finishes to textiles. Common
examples include:
• Soil release
• Antisoil
210
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• Stain blocker
• Antistatic
• Softeners
• Flame retardants
* • Water repellent
• Biocides
Often, these finishes are applied with minimal knowl-
edge of the potential impacts on indoor air quality. An
example is stain-release fluorocarbon finishes for uphol-
stery, which can perform poorly if not applied properly.
The poor performance results in excessive cleaning
requirements, solvent use, and indoor air pollution. In
general, greater attention needs to be given to the se-
lection and use of topical finishes.
4.16 Consumer Issues and
Consumer Care
The following table introduces the pollutants and waste
streams discussed in this section, as well as suggested
pollution prevention activities for each.
Pollutant or Pollution Prevention Actions
Waste Stream Described in This Section Comments
4.16, Customer Care
General Vendor/customer information
exchange; design of textile and also
of composite products; purchasing
specifications; better general
expertise; storage conditions
Most textile products require regular consumer care and
maintenance. Consumers use a variety of aftermarket
cleaning products, which they must select and use prop-
erly because improper use can lead to problems such
as indoor air pollution. For example, inappropriate or
improperly applied cleaning materials cem produce long-
term indoor air pollution. The same can be said for other
consumer activities, such as dry cleaning of garments
and spot removal from carpets and upholstery.
Smith and Bristow (83) report that industry working
groups have identified several important consumer is-
sues regarding indoor air pollution. These relate to tex-
tile products and materials that interact with textile
products:
• Consumer attitudes and information
• Cleaning product selection and use
• Cosmetics, toiletries, and personal products
• Deodorizers, room fresheners, and perfumes
• Consumer use patterns and practices
• Interaction with hobby materials
• Use of pesticides
• Solvent uses
Currently, no protocol exists for providing consumers
with information regarding air pollution issues. With the
recent emphasis on indoor air quality, however, industry
programs are likely to be developed.
4.17 Globalization of Pollution Prevention
The most difficult aspect of pollution prevention, and the
aspect that can perhaps pay the highest dividends, is
globalization of pollution prevention concepts. Most tex-
tile manufacturers have approached pollution preven-
tion on a process-by-process basis, but few have
globalized these concepts. Each part of the process—
beginning with design, purchasing, and training, and
continuing all the way through the unit manufacturing
processes, and finally ending with distribution, merchan-
dising, and cut and sew—affects all other parts. A suc-
cessful pollution prevention program must be
comprehensive and include every aspect of textile
manufacturing from R&D to marketing (91). This is a
great challenge because of the textile industry's ex-
tremely fragmented nature.
The basic premise of pollution prevention is globaliza-
tion. Treatment systems often create chains of waste or
move waste from one medium to another, so to be
effective, pollution prevention must focus on treatment
systems as a whole rather than fragments of these
systems. Fava and Page (92) present pollution preven-
tion as a global multimedia approach, which is prefer-
able to medium-by-medium attacks on pollution (92).
The pollution prevention approach can be globalized
beyond unit processes to evaluate the entire life cycle
analysis of pollution associated with products (92).
These concepts must have a broad focus and embrace
all parts of the operation (65).
Berglund and Snyder (93) give a graphic depiction of
globalization of pollution prevention concepts, integrat-
ing ideas such as source reduction .and recycling and
also present the relationship of process development
from conception through laboratory, pilot plant, and com-
mercialization (see Figure 3-2). The further along in
process development, the more difficult and costly pol-
lution prevention efforts become to implement; there-
fore, considering pollution prevention at the design
stage is the easiest, most economical approach (see
also Section 3.2, "Design-Stage Planning"). Interdiscipli-
nary team reviews are useful to integrate the perspec-
tives of customers, regulators, and raw material suppliers
in order to identify alternatives, select raw material sup-
pliers, and evaluate options based on future regulatory
factors (93).
211
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4.17.1 Scope of Globalization
A tally global approach to pollution prevention coordi-
nates all manufacturing segments to produce minimum
overall waste, including:
• Dye and chemical suppliers.
• Designers of fabrics.
• Merchandisers.
• R&D.
• Customers.
• Support functions.
• Production scheduling.
• Maintenance.
• Personnel training.
• Purchasing.
• The entire manufacturing pipeline, including spinning,
weaving/knitting, dyeing/finishing, and cut and sew.
• Regulators.
Individual process tweaking can accomplish significant
changes, but a process-by-process examination of pol-
lution prevention does not accomplish as much as a
globalized pollution prevention program (91, 94).
4.17.2 Barriers to Globalization
Pollution prevention faces significant barriers, involving
mainly the lack of global attitudes (95). Primary disin-
centives include risk of change, inadequate recognition
of benefits because of nonglobal costing procedures,
and lack of information and communications. A suc-
cessful pollution prevention program eliminates these
disincentives through improved information, employee
understanding, quality evaluations, and effective cost
systems (95). Above all, a global perspective and
better understanding of pollution prevention need to be
fostered among employees (95). Wagner (14) provides
a sketch of the role of supplier, finisher, and regulator in
a globalized pollution prevention scheme (see Figure
4-23). To move forward with pollution prevention, the
industry must change its way of thinking; and a united
and integrated effort must be undertaken by the vendor,
processor, and customer (60). For example, suppliers
should provide product information to wet processors
and accept responsibility for reuse of packaging and
shipping materials (66).
4.17.3 Examples of Globalization
Every business is different, just as every mill is different,
so specifying how to globalize pollution prevention
programs in all settings is impossible. The following
examples are typical, however, and could be imple-
mented in most operations:
• Preparation versus upstream/downstream compatibility.
• Designer/finisher/customer communications to reduce
chemical finishing.
• Enhanced information exchange.
4.17.3.1 Preparation
In textile manufacturing, chemicals are often added in
the processing stages. These chemicals must later be
removed by energy and chemically intensive scouring
procedures. Minimization of upstream chemical resi-
dues is important in the reduction of toxic pollutants from
effluents for cotton and synthetic dyeing (96). Examples
of these chemical residues include:
• Lubricants
• Spin finishes
• Agricultural chemicals
• Size materials-
• Knitting oils
• Winding lubricants
• Tints
An overall global pollution prevention scheme should
consider the downstream impact of all processing resi-
dues. Mills should set up dyeing and finishing processes
that minimize chemical residues from spin finishes,
agricultural chemicals, sizes, oils, tints, and winding
emulsions. Finishers and dyers often attempt this un-
successfully because of a lack of information about
upstream processes (92). One solution is to overcome
the proprietary nature of chemical specialties and move
toward global selection of compatible processing assis-
tants. The barriers to this approach are great, but the
potential rewards are immense.
Additives should be selected, wherever possible, that
will not interfere with downstream processes. For yarn
manufacturing, low BOD winding emulsions and waxes
are commercially available that do not generate waste-
water pollutants when removed from the yarn fibers. In
addition, they help reduce the normally high oxygen
demand loads in wastewater produced during fiber
preparation. In this way, globalization across unit proc-
ess boundaries can prevent pollution.
4.17.3.2 Designer/Vendor/Supplier/Finisher/
Customer Globalization
Many knit fabrics normally require chemical resin stabi-
lization for shrinkage control and sewability (82). Often,
however, mills can stabilize these fabrics without using
chemicals, provided the equilibrium relaxed configuration
212
-------
Dye/Chemical Manufacturer
Product Development
« High Exhaustion
•Low:
Toxicity
COD
Metal Content
Process Development
• Reproducible/Robust
• Low Liquor Amounts
• Less Chemicals
• Shorter Dyeing Time
• Lower Temperatures
• Dyebath Reuseable
Textile Processor
Optimize:
• Product Selection
• Formulations
• Processes
• Housekeeping
Recycle Wherever
Possible
Implement Effective
Waste Treatment
Communicate
Efforts and
Successes
Authorities
Cooperate With
Industry To
Develop Rational
Solutions
Do Not Force
Export of
Environmental
Problems
Educate Population
Amount Risk/Benefit
of Required
Technologies
Figure 4-23. An integrated approach to environmental problems in the textile industry (14).
of the fabric is exactly equal to the customer specifica-
tion in terms of width, yield, and shrinkage and provided
that complete relaxation is attained (82). The pollution
that results from chemical fabric stabilizers, stiffeners,
and softeners can be reduced by better knit designs,
which inherently require less chemical stabilization.
Proper fabric design and handling can eliminate much
of the need for chemicals.
Commercially available computer-assisted fabric design
programs aid in yarn selection, tensions, stitch length,
machine cut and diameter, and other parameters for
making a customer-specified construction at the proper
width, yield, and shrinkage (82). The concept of design
as a shrinkage control tool is a good example of globali-
zation. If the customer can be integrated into the proc-
ess to correlate the finished goods specifications with
the design parameters, then the finisher's job is mostly
a matter of tensionless handling. Few if any chemicals
are needed. (See Section 4.12, "Finishing," for more
information). In fact, if the need to prepare cloth in order
to remove upstream impurities and to overcome techni-
cal design deficiencies were eliminated, then dyeing and
printing would be the main task of wet processing and
the need for finishing would be reduced.
An example of globalization is in the area of color match-
ing (see also Section 4.3.4). In most markets, essentially
all shades are matched to customer- or designer-speci-
fied standards. In some cases (e.g., bright green, royal
blue, deep violet), metal-bearing dyes are required to
match the specified shade. Often, a slight modification
of hue, value (depth), or chroma (brightness) could re-
sult in the reduction or elimination of the metal-bearing
dye from the recipe. This would reduce metals in the
textile mill wastewater effluent or waste treatment sludges.
Few if any companies take the time to inform designers
of these alternatives, and thus the designer never be-
comes aware of the environmental implications of the
color selection. Designers should be free to select
colors they need to meet aesthetic design criteria, but
they should be made aware of the consequences and
alternatives.
Another example is vendor/customer relationships. For
a pollution prevention program to be complete, vendors
must become involved. The result of such cooperation
is that customers and vendors ultimately agree on
standard QC tests, purchasing specifications for con-
tents, impurities, packaging, and other issues. In the
textile industry, this requires continual effort on the part
of the mill. A good incoming QC check system, and
constant review of methods and test results, even when
no problems are evident, builds the necessary cus-
tomer/vendor relationships. The result can be lower pol-
lution and better quality.
4.17.3.3 The Role of Information Exchange in
Globalization
As mentioned above, a global perspective requires ac-
curate information (92) and a system for exchanging the
information. Incentives to establish such a system are
also necessary, and these can be difficult to establish in
a fragmented manufacturing complex such as textiles.
Globalization includes not only design, additives' effects
on downstream processing, and the need for later re-
moval by scouring but also development of an overall
view of manufacturing equipment to eliminate solvent
loss, dragout, and impurity buildup. These concepts can
be extended to the consumer level, aftermarket treat-
ments, cleaning solvents, use conditions, installation,
maintenance, and ultimately product recycling.
In the dyestuff and textile chemical business, the pro-
prietary nature of products and processes often ham-
pers pollution prevention opportunities (91). The methods,
difficulties, and rewards of this information exchange are
discussed in other sections of this document:
213
-------
• Section 3.12, "Raw Material Prescreening."
• Section 3.13, "Disinformation About Environmental
Issues."
• Section 4.3, "Dyes."
• Section 4.4, "Chemical Specialties."
• Section 6.5, "Risk Assessment."
Information exchange has been useful in designing and
upgrading cost systems. Glover and Hill (65) and
Moore10 present methods for equating the cost of sev-
eral complex types of pollution in the same terms as
other cost factors now in cost systems, thus allowing
more incisive risk/benefit analysis. Computer models
are widely used to equate the effects of factors such as
off-quality, delivery, and pollution.
4.77.4 Priorities and Commitments
A company's business priorities and commitments con-
trol, to a large extent, its ability to globalize its pollution
prevention program. Technical pollution prevention ac-
tivities are usually site-specific and process-related, but
globalization of pollution prevention must be based on a
high level of technical understanding that transcends
production unit boundaries. This is a difficult criterion to
fulfill because those with broad-ranging resources and
responsibilities rarely have the required level of techni-
cal expertise. This is a crucial point, especially because
most pollution prevention activities involve complex
technical tradeoffs. Establishing the required communi-
cations is difficult enough, but information exchange is
not an end in itself; instead, it is a way for each unit to
understand another's predicament. Some companies
have already successfully explored ways to develop
special global business relationships between suppliers,
manufacturing sites, support groups, and customers.
4.18 Support Work Areas
Textile processing operations comprise several different
types of chemical mixing areas, including print color
shops, dye drug rooms, slasher kitchens, and size mix
kitchens. Because the majority of chemicals in the mill
are handled and dispensed from these areas, they have
the potential to produce more pollution than all other
parts of the mill combined. Therefore, they deserve
special attention. Some of the important pollution pre-
vention aspects of chemical mixing areas are:
• Design features
• Employee attitudes and work practices
10 Moore, S., and B. Smith, 1994. Personal communication between
Samuel Moore, Burlington Research, Burlington, NO, and Brent
Smith, Department of Textile Chemistry, North Carolina State Uni-
versity, Raleigh, NC.
• Implements
• Mix tanks
• Cleanup practices
• Automated chemical dispensing systems
These will be discussed in further detail in this section.
4.18.1 Design Features
Design features of chemical mixing areas are an impor-
tant consideration when developing a pollution preven-
tion program. The following issues should be considered:
• Chemical mixing areas should be well lit and well
ventilated and should provide ample work space so
that they remain neat and orderly even when in full
use. This is important in creating a careful work atti-
tude among employees.
• The ventilation system should feature temperature
and humidity control. Sorption of moisture from the
atmosphere may result in a 4-percent to 20-percent
error in dye weight (97).
• The area should be located as close to the production
machines as possible (and practical), but not out in
the open production area itself. A mezzanine location
is ideal, if properly cooled and ventilated.
• The floor should be smooth, well sealed, and have
good drainage, which facilitates cleanup. A vacuum
should be available to capture powder spills. Under
no circumstances should spills be washed down the
drain with water from a hose.
• Drums and bags of chemicals should not be stored
in standing water or over floor drains. Spill contain-
ment pallets are useful in preventing small-scale
spills. All drums should be tested when opened (see
Section 4.4, "Chemical Specialties") and marked with
the opening date. This allows quick determination of
the age of chemicals and verifies that they were
tested when received.
• Leaks and drips should be repaired immediately, and
all hoses should have automatic shutoff valves so
they cannot keep running when laid down.
Additional information about design features is pre-
sented in Section 3.2.3, "Design-Stage Planning for
Facilities."
4.18.2 Employee Work Practices
Constant training and retraining of employees is neces-
sary to maintain the proper attitude and work practices.
Mills need to keep employees up-to-date on pollution
prevention techniques and make them aware of the
long-term benefits of pollution prevention.
214
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Chemical mixing areas are one place where employees
should focus on pollution prevention. An average worker
in a drug room or color kitchen makes; 300 weighings
per day (97). Often, these weighings involve several
hundred pounds of chemicals or dyes. Atypical large mill
that dyes 100,000 pounds of cloth per day might weigh
approximately 1 ton of dye per day. Increasing dyebath
exhaustion as an effective method of pollution preven-
tion for color in wastewater is discussed in Sections 4.3,
"Dyes," and 4.10, "Dyeing," but it is no more important
than avoiding small spills and implement cleaning in the
drug room.
As an example, if 2,000 pounds of dye were put into
dyeing machines and the exhaustion were 95 percent,
then 100 pounds would be discharged. If, on the other
hand, 4 ounces of dye per weighing were spilled,
washed off of implements, or drained from pasteup
buckets for 300 weighings per day, that would be 75
pounds of dye ([300 * 4]/16). In such a case, over 40
percent of the total color discharge is from weighing.
Information pertinent to this topic is also discussed in
Section 3.11, "Optimized Chemical Handling Practices."
4.18.3 Implements
The use of proper implements and equipment in chemi-
cal mixing areas can greatly reduce chemical waste
through misweighings, spills, and washoffs. Some of
these issues are discussed in the following paragraphs.
Careful weighing of chemicals is essential to right-first-
time production, so scales are the most important piece
of equipment in the drug room. The inaccurate weighing
of chemicals by the dipperfull or with inappropriate
scales can lead to weight discrepancies. Although
chemical weighing does not require the same precision
as dyestuff weighing, produce scales are not accurate
and precise enough for chemical weighing. In addition
to having the proper scales, employees must maintain
and calibrate the scales frequently.
Manual handling of dyes and chemicals generally is
done by dipping the chemical out of the drum, weighing
it into a bucket, then putting the weighed amount into a
mix tank with water and other mix components. The
usual procedure is then to wash the dipper and the
bucket. If a different dipper is used for each chemical, it
does not require washing because it will always be used
to measure the same chemical. The use of automatic
dispensing to the mix tanks is preferable to manual
handling because it avoids all containerized handling
and saves time and potential errors associated with
manual weighing. These issues will be discussed below.
4.18.4 Mix Tanks
Mix tanks should be made with volume marks on the
inside so that any desired amount of mix can be formu-
lated. One useful method is to etch a volume scale on
a stainless steel vertical rod welded inside of the tank.
Volume marks in 5- or 10-gallon increments are normally
used.
4.18.5 Cleanup Practices
Efficient and proper cleanup practices in chemical mix-
ing areas are important aspects of pollution prevention.
Cleanup practices include:
• Workers should never wash drums in the mix kitchen
or dispose of obsolete dyes and chemicals down the
drain. When a drum of chemicals is empty and a new
one is opened, the old drum should be emptied or
drained thoroughly into the new. (Of course, return-
able IBCs are preferred.)
• In pigment printing operations, assess screen and
squeegee cleaning, which is a major source of color,
as well as suspended solids, in the wastewater.
• Implement (buckets/dippers, other containers) cleanup
is important, as discussed above.
• Automated chemical systems are by far the most
preferable because they require infrequent cleaning.
4.18.6 Automated Chemical Dispensing
Systems
An important innovation in chemical handling is the
automated drug room (10). Drug rooms improve right-
first-time dyeings, improve quality, reduce reworks, de-
crease handling, and prevent waste (10). They can also
correct for off-specification dyes, for example, by auto-
matically adjusting formulas to compensate for drum-to-
drum dye strength variations. In addition, automated
drug rooms reduce mismade mixes and the amount of
waste that results from mismade mixes.
Dry dispensing systems for powder dyes are available
that are fast and accurate (97). These are shown in
Figures 4-24 and 4-25. The systems feature storage
compartments, valves, weighing devices, and mechani-
cal parts that are extremely resistant to corrosion and
are easy to clean (97). Precision of 0.01 gram on a
10-kilogram delivery is available, and the accuracy is
within 1 percent. The system also includes hard auto-
mated container transport to and from the dispensing
area (97). Similar systems are available for liquid dis-
pensing. These interface directly to IBCs, eliminating
any manual handling at all.
These systems improve pollution prevention by improv-
ing handling, as well as the accuracy of color and chemical
dispensing. If color is inaccurately dispensed, corrective
additions must later be made to the dyeing, which not
only increases color use but also may decrease color
exhaust, require additional time, chemicals, and energy,
215
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^"'"Dye'!-h
:. Powder .'/
^•/^i
Archimedes' Screw
Pneumatic Vibrating
Mechanism
Vibrascrew Dispense
Valve
Dust Extraction
Hood
Dust Extract
Figure 4-24. Vibrascrew dispense system (97).
Figure 4-25. Dispense and weigh scale set-up (97).
and in some cases require stripping and redyeing, the
costliest outcome in terms of economics and pollution.
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Chapter 5
Implementation of a Pollution Prevention Program
Environmental concerns and costs associated with
waste generation, handling, disposal, and liability have
raised awareness about the importance of waste man-
agement and prevention practices. Incorporating pollu-
tion prevention into a company's overall business
strategy is the most effective way to address these
concerns and capitalize on the numerous benefits re-
sulting from prevention efforts. Many companies have
found it advantageous to model their pollution preven-
tion programs on, and integrate them into, existing total
quality management (TQM) programs (1).1
This chapter describes the steps needed to integrate
pollution prevention into the business environment and
develop and implement a successful, sustainable pollu-
tion prevention program.
5.1 Steps in Implementation
Implementing a pollution prevention program involves
several steps:
• Designating a pollution prevention coordinator.
• Establishing management commitment and support.
• Organizing a team to lead the pollution prevention
effort.
• Developing a pollution prevention plan.
• Developing a process flow diagram.
• Setting goals and priorities for the pollution preven-
tion program.
• Developing an action plan.
• Implementing the action plan.
• Expanding the plan to meet future goals and priorities.
The following subsections outline these basic steps for
implementing a successful pollution prevention program.
1 When companies apply TQM-type tools and principles to environ-
mental issues, they often refer to it as total quality environmental
management (TQEM). TQEM is the environmental management
method endorsed by the Global Environmental Management Initia-
tive (GEMI), an organization with a membership of approximately 30
leading industrial corporations. For further information, see Wells et
al. (2).
5.1.1 Establishing Management Commitment
and Support
No pollution prevention program succeeds without
genuine management commitment to the prevention
philosophy. Employees look to management for guid-
ance on how to carry out their daily tasks. Thus, if
management places strong emphasis on pollution pre-
vention, employees will as well. On the other hand, if
management sees pollution prevention as an easy way
to pass the buck to workers, the pollution prevention
program will fail. In short, if management makes a seri-
ous commitment to pollution prevention, that commit-
ment will filter down through all levels of the textile
operation.
Many companies demonstrate their commitment to pol-
lution prevention by establishing and endorsing a written
pollution prevention policy. Once endorsed by manage-
ment, the policy should be distributed to all employees
to raise their awareness about pollution prevention. A
sample corporate policy statement on pollution preven-
tion is shown in Figure 5-1 (2).
Management also needs to provide leadership in edu-
cating employees about pollution prevention, its rela-
tionship to the company's business strategy, its potential
to benefit the company, and its impact on how employ-
ees do their jobs. One way for management to introduce
employees to pollution prevention concepts is to pre-
pare a short oral or written presentation. Suggested
topics could include (3):
• Cost savings through reduced raw material use, as
well as reduced waste,handling, transportation, and
storage costs.
• Increased productivity.
• Improved product quality.
• Regulatory compliance.
• Worker health and safety.
• Reduction of potential long-term liability.
• Examples of other companies' achievements.
• Improved public image for the company.
219
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We, [company name]/ are committed to excellence and leadership in pro-
tecting the environment. In keeping with this policy, our objective is to
reduce waste generation and emissions. We strive to minimize adverse
impact on the air, water, and land through excellence in pollution preven-
tion. By successfully preventing pollution at its source, we can achieve cost
savings, increase operational efficiencies, improve the quality of our prod-
ucts and services, and maintain a safe and healthy workplace for our
employees.
[Company name]'s environmental guidelines include the following:
• Environmental protection is everyone's responsibility. It is valued and
displays commitment to [company name].
• Preventing pollution by reducing and eliminating the generation of waste
and emissions at the source is a prime consideration in research, process
design, and plant operations. [Company name] is committed to identifying
and implementing pollution prevention opportunities through encourage-
ment and involvement of all employees.
» Technologies and techniques which substitute nonhazardous materials
and utilize other source reduction approaches will be given top priority in
addressing all environmental issues.
• [Company name] seeks to demonstrate its corporate citizenship by adher-
ing to all environmental regulations. We promote cooperation and coordi-
nation between industry, government, and the public toward the shared
goal of preventing pollution at its source.
Figure 5-1. A management policy statement (4).
• Emphasis that the U.S. Environmental Protection
Agency (EPA) and states place on pollution preven-
tion as an environmental protection policy.
Case studies can be very effective in communicating
how other companies have approached pollution pre-
vention problems, the actions taken, and the results.
Chapter 7 of this document summarizes case studies of
pollution prevention in the textile industry. Case studies
from industries besides textiles are also worthy of review
because solutions identified in one industry can often be
successfully transferred and applied in many other in-
dustries.
Management should also seek assistance from state
environmental agencies and EPA. Staff from these
agencies as well as consultants may be able to provide
technical assistance in establishing a pollution preven-
tion program. EPA operates a Pollution Prevention Infor-
mation Clearinghouse that can provide documents, fact
sheets, case studies, and other reference material on
pollution prevention. EPA's Enviro$en$e bulletin board,
also accessible through the Internet, is a repository of
information on pollution prevention, technical assis-
tance, and environmental compliance.2
z The EnviroSenSe bulletin board can be reached at (703) 908-2092.
The URL for access via the Internet's World Wide Web is: http://
wastertot.lnel.gov/enviro-sense.
5.1.2 Designating a Pollution Prevention
Coordinator
A successful pollution prevention program requires not
only support from top management but also input and
participation from all levels of the organization. To organ-
ize the effort, every pollution prevention program needs
an effective pollution prevention coordinator.
The pollution prevention coordinator establishes pollu-
tion prevention teams and work groups, organizes and
conducts meetings, and tracks the progress being made
toward reaching pollution prevention goals. Most often,
the coordinator comes from middle-management levels.
The ideal person is not necessarily the one who knows
the most about wastes; an individual with good organ-
izational skills and leadership qualities who can motivate
people and communicate needs and results is also a
good candidate.
5.1.3 Organizing a Pollution Prevention Team
After establishing management commitment, general
goals, and resources, and naming a pollution prevention
coordinator, a pollution prevention team should be or-
ganized to lead the effort. The team should consist of
people with different backgrounds and expertise to bring
to the pollution prevention process as well as anyone
else who expresses an interest (volunteers should
220
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always be welcome). The team should include both
front-line and supervisory personnel.
The list of recommended members for the chemical
prescreening committee (see Section 4.4.4.2) is a good
start, perhaps with some modifications:
• Industrial hygienist
• Industrial engineer
• Plant engineer/shop foreman
• Laboratory manager/chemist
• Legal representative
• Wage hour worker representative
• Purchasing agent
• Personnel manager
Team-building can begin with an initial meeting to dis-
cuss general concepts of pollution prevention, how the
company can gain from pollution prevention, and brain-
storming on how to develop a pollution prevention plan,
the first formal step in the process.
5.1.4 Developing a Pollution Prevention Plan
The pollution prevention plan should be the first task of
the pollution prevention team. Some facilities may al-
ready have a pollution prevention plan because some
states require them. The plan envisioned here is not a
list of projects to be undertaken; rather, it is a formal
guide to how the team will conduct its business. The
plan should cover or include:
• A statement of support from management.
• The structure, philosophy, guidelines, and purpose of
the pollution prevention team.
• Concrete plans for encouraging participation from all
employees in the facility.
• The structure of any incentive or reward programs to
be introduced.
• Procedures for conducting process evaluations and
identifying pollution prevention opportunities.
• Procedures, criteria, and schedules for implementing
pollution prevention projects.
• Provisions for employee training, where necessary.
• Resources needed to conduct program activities.
Developing a viable pollution prevention program re-
quires that the company adopts the pollution prevention
plan as part of its overall operating procedures and that
everyone understands and accepts the principles and
ideas the plan contains. To help in this regard, the plan
should be presented to top management so that man-
agement knows what the pollution prevention team is
doing, how the team will conduct its assessments, and
what types of resource commitment are necessary.
5.1.5 Developing a Process Flow Diagram
One of the most important tasks of the pollution preven-
tion team is to develop a process flow diagram, or
process map (5). Process mapping breaks down the
operations of the facility into functional unit operations,
each of which can be portrayed in terms of material
inputs, outputs, and losses. Developing the process
map helps the pollution prevention team form a consen-
sus about how the production process is organized and
provides a focal point for identifying and prioritizing pol-
lution prevention opportunities, as shown below. It is
also a powerful communication tool that can be used to
convey information to workers and management about
trouble spots and to pinpoint process areas that require
attention. Useful information for constructing the proc-
ess map may be obtained from sources such as those
shown in Table 5-1 (6).
The process map should cover the main operations of
the facility and any ancillary operations (e.g., shipping
and receiving, chemical mixing areas, maintenance
Table 5-1. Sources of Facility Information (6)
Type of Information Sources of Information
Regulatory information
Process information
Raw material/
production information
Accounting information
Waste shipment manifests
Emission inventories
Biennial hazardous waste reports
Waste, wastewater, and air emission
analyses
Environmental audit reports
Permits and/or permit applications
Form R for SARAa Title ill, Sec. 313
(Toxics Release Inventory)
Process flow diagrams
Design and actual material and heat
balances
Product composition and batch sheets
Material application diagrams
MSDSs"
Product and raw material inventory
records
Operator data logs
Operating procedures
Production schedules
Waste handling, treatment, and
disposal costs
Water and sewer costs, including
surcharges
Costs for disposal of nonhazardous
waste, such as trash and scrap metal
Product, energy, and raw material costs
SARA = Superfund Amendments and Reauthorization Act.
MSDS = material safety data sheet.
221
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operations). Another extremely useful addition to the
diagram is a depiction of upstream and downstream
operations because in textiles, pollution and waste is-
sues often cross facility boundaries (e.g., chemicals
added at the spinning mill are removed and become a
waste at the weaving orfinishing mill). An understanding
of where pollution originates and where it ultimately
ends up is thus very important for global pollution
prevention.
As simple as this diagram may appear, the effort needed
to complete such a diagram is often surprising, as is the
amount of debate that can develop over exactly how the
facility operates. Figures 5-2 and 5-3 provide examples
of life-cycle process maps for production of a knit cotton
golf shirt and a polyester woven dress. Note that in both
cases, the maps begin with the production of the raw
material (seed cotton for the golf shirt and polyester
filament for the dress) and end with delivery of the
finished product to the retail distributor, even though the
facility (e.g., a finishing operation) may occupy only a
portion of the process map. As emphasized throughout
this manual, pollution prevention in textiles often re-
quires a global view of operations and an understanding
of what happens to the materials or product beyond the
facility boundaries.
Once the basic unit operations are identified and the
sequence of operations is laid down in a working dia-
gram, the pollution prevention team should walkthrough
the facility to verify and validate the diagram, as de-
scribed in Section 5.2, "Waste Audit." Modifications to
the diagram can be made as observations and discus-
sions with process operators or supervisors sharpen the
team's understanding of unit operations.
During the walkthrough, the team should attempt to
complete a materials accounting for each process, iden-
tifying all inputs and outputs for each unit operation. The
team should focus on identifying points in the process
where wastes are generated. Wastes should be classi-
fied according to the environmental media to which they
are released (i.e., air, water, or land [solid and hazard-
ous waste]). Wherever possible, the amounts of waste
generated or lost from the process should also be quan-
tified (e.g., in pounds per week, gallons per hour). Es-
pecially important is the identification not only of wastes
intentionally generated (e.g., dumped batches of size or
finishing chemicals) but also of losses attributable to
leaks and spills, losses associated with equipment
cleanup and maintenance (e.g., during color changes),
and losses resulting from off-specification production
runs. Some types of losses may not be readily observ-
able during a facility walkthrough and may only be iden-
tified through discussions with operators or floor
supervisors.
Another important step is to observe operations and talk
to operators during all shifts at the facility because
losses associated with certain operations (e.g., cleaning
and maintenance) may be observable only during cer-
tain shifts. To help identify and quantify wastes, the team
may need to examine purchasing and accounting re-
cords, inventories, standard operating procedures, pro-
duction records, and waste disposal manifests (7).
5.1.6 Setting Goals and Priorities
After preparing the process map and conducting the
in-plant survey or audit, the team should prepare a
document based on the information collected. The docu-
ment should contain 1) a list of all waste streams, 2) any
general observations about the waste streams, and 3)
an assessment of pollution prevention procedures al-
ready in place. The information should be compiled by
reviewing facility operations at several different levels to
identify issues such as:
• Individual unit process issues
• Facilitywide issues
• Global/corporate issues
• Supplier/customer issues
The document should be used to develop specific lists
of goals and priorities for manufacturing processes as
well as support activities, such as maintenance, material
handling, training, and purchasing. Some goals may be
specific to particular wastes (e.g., eliminating the use of
solvent cleaners for a particular printing machine), while
others may apply to an entire department or the whole
facility. In addition to specific goals, the document
should also include general goals such as improving
worker health and safety or improving the company's
public image. The document should describe the current
practices and the pollution prevention team's objective
regarding future practices, thus serving as the baseline
for future progress assessments.
5.1.7 Developing an Action Plan
Once goals and priorities have been set and have been
endorsed by those involved (e.g., management, produc-
tion, suppliers, customers), the team should develop an
action plan, keeping in mind the general categories of
pollution prevention techniques described in Chapter 3:
• Design-stage planning for processes and products.
• Developing enhanced expertise and competence.
• Equipment maintenance and operations audit.
• A global, integrated view of manufacturing.
• Chemical alternatives.
• High-extraction, low-carryover process step separations.
• Incoming raw material quality control (QC).
222
-------
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227
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Figure 5-3. Materials flow for polyester woven dress (continued).
228
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Figure 5-3. Materials flow for polyester woven dress (continued).
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229
-------
• Maintenance, cleaning, and nonprocess chemical
control.
* Developing markets for wastes.
• Process alternatives.
• Optimized chemical handling practices.
• Raw material prescreening (before use).
• Reducing disinformation and politics.
• Scheduling dyeing operations to minimize machine
cleaning.
• Standard tests, methods, and definitions.
• Consumer, installer, and end-user information.
• Technology transfer of pollution prevention successes.
• Training programs and worker attitudes.
• Segregation, reuse, onsite recovery, and offsite
reuse.
• Inventory management
• Improved process control.
The action plan is based on ideas generated by pollution
prevention team members and, more importantly,, by
those most familiar with the processes (e.g., supervi-
sors, front-line workers). The team should develop a
multifaceted approach to soliciting ideas for pollution
prevention. Pollution prevention team members can
meet individually with small groups of employees famil-
iar with particular unit operations to brainstorm about
waste and pollution issues and to develop ideas. A
pollution prevention suggestion box can be used to
encourage people to contribute ideas outside of these
sessions or anonymously. All ideas should be taken
seriously, and none should be rejected automatically for
reasons such as That's already been tried," 'That'll
never work," or That's too expensive." Pollution preven-
tion is about finding new and sometimes unconventional
ways of doing things, and many of the best pollution
prevention ideas probably sounded outlandish when
first proposed.
Every pollution prevention idea should be reviewed to
determine if it can help the mill achieve its pollution pre-
vention goals. Ideas should be developed for each waste
stream and each process in all high-priority areas. The
techniques should be both general and process-specific
and should include design changes, new equipment
acquisition, and potentially major business changes.
Each technique should be carefully evaluated on a tech-
nical and an economic basis. From these, the optimum
outcome should be selected and an action plan drafted.
The selection of the optimum outcome is subjective and
site-specific. In addition to having the proper pollution
prevention techniques, a pollution prevention program
must have flexibility to accommodate new processes,
styles of cloth, and unforeseen market events.
Employee involvement and commitment to the pollution
prevention effort is crucial. While numerous checklists
are available that provide ideas for pollution prevention
projects, the best source of suggestions and innovations
is employees involved in daily mill operations. Getting
employees involved requires ensuring that they have a
solid understanding of pollution prevention and of the
company's pollution prevention goals. Training and in-
centive programs are very useful in encouraging em-
ployee involvement. For example, one manufacturer
posted all waste types and amounts from each machine
. on a sign mounted on the machine. Whenever an
employee found a way to reduce or eliminate waste,
the employee's name was added to the sign along with
the type and amount of waste reduction. Other compa-
nies have put a "bounty" on waste and organized people
against waste (PAW) groups. Employee contributions
should be acknowledged in newsletters or other com-
munications about the pollution prevention program.
5.1.8 Implementing the Action Plan
The next step is actual implementation of the plan. This
consists of carrying out the selected techniques on the
production floor, monitoring the results, and providing
feedback. In many cases, in-house resources are ade-
quate for pollution prevention implementation. In other
cases, however, outside assistance may be needed.
Implementation must be viewed as an ongoing process,
not simply a one-time activity. Once the pollution preven-
tion program is in progress, the pollution prevention
team should continue assessing, quantifying, and docu-
menting pollution prevention progress, giving feedback
to those involved in production areas. Waste streams
should be monitored and documented, with follow-up
technical and economic evaluations.
5.1.9 Expanding the Action Plan
Once implemented at the unit process level, the pollution
prevention plan should be expanded to broader levels
(i.e., facilitywide as well as corporate and supplier/cus-
tomer levels) and should be combined with the com-
pany's future goals. These goals may include:
• Long-term planning
• Research and development (R&D)
• Product and process design
• Purchasing specifications (including packaging)
• Customer relations
• TQM programs
In expanding the plan to a broader level, the company
will benefit by making the community, customers, and
230
-------
suppliers aware of pollution prevention successes and
by considering their concerns in future planning. Partici-
pating in technology transfer of pollution prevention suc-
cesses is also advantageous, as is supporting the
pollution prevention efforts of other textile companies,
suppliers, customers, trade associations, and local busi-
nesses. In fact, many companies have used pollution
prevention ideas originated at their own facilities as the
starting point for new business areas.
5.1.10 Renewal
Similar to TQM programs, pollution prevention programs
should incorporate a feedback loop. Finally, priorities
should be reassessed and new, higher; and more global
goals should be set.
5.2 Waste Audit3
Like manufacturers in most industries,, textile manufac-
turers produce and ultimately discard four types of
waste: wastewater, toxic air emissions,, solid waste, and
hazardous waste. Although manufacturers use different
methods for handling each waste, the basic approach to
each should be identification, elimination, and reduction.
The first step in successful waste management begins
with identification of waste types and amounts, and the
tool most commonly used is a waste audit (9).
A waste audit is a facility assessment designed to collect
technical and economic information in order to assess
appropriate waste reduction techniques. The audit is
probably the most important single item in the imple-
mentation of a pollution prevention program. It allows
the identification and quantification of individual waste
streams and allows the identification of practices, pro-
cedures, and processes that lead to waste generation.
The information collected in the waste audit can be used
to select and evaluate^appropriate waste reduction and
management techniques (9).
Mills can approach a waste audit in many different ways.
This section discusses the steps that have been most
widely recommended (8-13). While these steps can
serve as a checklist to begin planning for the waste
audit, the most important rule for any pollution preven-
tion program is to think. Do not rely entirely on lists and
forms. No pollution prevention checklist has ever been
written, or ever will be written, that can rival a thinking
employee.
The following suggested protocol for an audit is an
expansion of the method suggested by North Carolina
Office of Waste Reduction, which identifies the following
as important steps in a successful waste audit (14):
• Identify all normal discharges.
g
Unless otherwise noted, the information contained in this section is
from Hunt (8).
• Identify potential abnormal discharges: bulk, obsolete,
discards.
• Characterize all emissions and discharges by type,
quantity, and content through sampling and testing.
• Evaluate treatment/disposal methods currently in
use.
• Assess compliance status.
• Assess current waste costs.
• Formulate an action plan for an aggressive attack on
waste.
• Establish an attitude throughout the facility that:
- Raw materials are a valuable limited resource.
- Waste of raw materials, energy, water, and chemi-
cal processing assistants is unacceptable.
Either one person or a team of people can perform the
audit. The team approach is preferable because a
team brings a wider range of knowledge and experi-
ence to the audit. An in-house team should include
personnel from:
• Management
• Plant engineering
• Environmental engineering
• Safety and health
• Purchasing
« Finance
• QC
For the waste audit to succeed, the team also needs a
leader who has both authority and technical expertise.
Involving a financial or accounting specialist in the waste
audit is also important. Often, the costs of waste treat-
ment and disposal are seen as a fixed overhead item
(the price of doing business) and are not well known.
Cost accounting systems that do not assign the costs of
waste treatment and disposal to individual product lines
or operating departments make encouraging waste re-
duction in those areas difficult (14). EPA has sponsored
several projects to improve awareness of this problem
in industry and is developing tools to assist in evaluating
pollution prevention projects.
5.2.1 Steps for Performing a Waste Audit
The process of conducting a waste audit should include
the collection of information on types, quantities, com-
positions, and sources of all air, solid, hazardous, and
wastewater waste streams. In many cases, this informa-
tion can be obtained through background data and sup-
plemented with observed data from the plant survey.
231
-------
5.2.1.1 Background Information
The first step in a successful waste audit is to collect all
available background information, including information
on production processes, facility layout, waste stream
generation, and waste management costs. This infor-
mation can be used to develop a general flow diagram
or material diagram for each process associated with the
facility. The diagram should identify the source, type,
quantity, and concentration of each identified waste
stream. The background information can further be used
to develop and organize the plant survey and to help
identify data gaps, sampling points, problem areas, and
data conflicts.
Background data collected before site inspection should
include the following:
• A determination of whether the facility uses any
chemicals subject to reporting requirements under
Title HI, Section 313, of the Superfund Amendments
and Reauthorization Act (SARA) (11).
• Production-oriented information:
— Process flow diagrams
— Plant layout
— Purchasing records
- Material safety data sheets (MSDSs)
— Operating manuals
• Water-use data:
— Plant operating schedule
— Production volumes
• Waste stream information:
— Waste manifests.
- Waste reports, as well as Toxic Release Inventory
(TRI) and Resource Conservation and Recovery
Act (RCRA) information.
- Permits: air, National Pollutant Discharge Elimina-
tion System (NPDES), publicly owned treatment
works (POTW) pretreatment, water, solid, hazard-
ous.
— Self-monitoring reports.
- Violations information and history.
— Waste collection and storage points.
- Layout of waste treatment systems (e.g., air,
water).
— Operating guides/manuals for waste treatment
systems.
— Chemical prescreening procedures (9).
- Incoming raw material QC procedures.
• Economic information:
— Waste and sewer bills
- Solid waste disposal costs
- Waste treatment system operating costs
— Contracts and consultants
• General:
- Current pollution prevention plan, if any
- Previous audits
- Vendor information
At the conclusion of the preliminary data collection
phase, the waste audit team should identify areas in
which data are missing and, to the extent possible,
develop a material balance. The data should be tabu-
lated in a standardized format.
5.2.1.2 Plant Survey
After collecting background information, the next step in
a waste audit is to conduct a plant survey. The plant
survey should be used to 1) verify and fill gaps in back-
ground data, 2) identify additional waste streams, and
3) observe and collect data on actual operation and
management practices. Each step of the manufacturing
process, from material delivery to final product, should
be investigated (see Tables 5-2 and 5-3).
If complete and detailed data on waste stream quantity
and composition are not available, then the survey proc-
ess should include development of a sampling program.
Before conducting the survey, sampling points should be
identified based on the waste flow diagram. These sam-
pling points are subject to change as the survey identi-
fies new waste streams.
5.2.2 Sampling
A program to sample and test waste streams of concern
should be designed to collect information regarding rou-
tine and nonroutine (exceptional) waste streams. The
information should include types, amount, composition,
and sources of all waste streams (i.e., air, water, solid,
hazardous) (8, 11). Some sampling guidelines to follow
include:
• Identify type of waste and point of origin (9, 11).
• Determine fate (e.g., waste treatment, storm sewer,
atmosphere).
• Determine rate produced or emissions factors (amount
produced per hour, per production unit) (8, 13).
• Determine variability (potential shock loading). •
In most cases, only qualitative data are needed for a
waste audit; however, in cases where quantitative data
are needed, sampling should be done over a sufficient
period to account for 1) variations in production sched-
uling and 2) seasonality or irregularity of production
schedules.
232
-------
Table 5-2. Potential Sources of Waste (4)
Plant Category Area Possible Waste Material
Table 5-3. Examples of Information Obtained From In-P(ant
Survey (4)
Material
receiving
Raw material
storage/final
product storage
Production
Area
Support
services
Loading docks,
incoming
pipelines,
receiving areas
Racks, silos,
warehouses,
drum storage
yards,
storerooms
Melting, curing,
baking,
distilling,
washing,
coating
machinery,
formulating
Laboratories
Maintenance
shops
Garages
Powerhouse/
boilers
Cooling towers
Packaging materials,
off-specification materials,
damaged containers, spill
residue, transfer-line
leaking/dumping
Tank bottoms;
off-specification and
excess materials; spill
residues; leaking pumps,
valves, (and pipes;
damaged containers;
empty containers
Washwa.ter, solvents; still
bottoms; off-specification
product; catalysts; empty
containers; sweepings;
duct cleanout; additives;
oil; process solution
dumps; rinsewater; excess
materials; filters; leaking
process tanks; spill
residue; pumps, pipes,
valves, and hoses
Reagents, off-specification
chemicals, samples,
sample containers
Solvents, cleaning agents,
degreasing sludges,
sandblasiting waste, lubes,
oils, greases, scrap metal,
caustics
Oils, filters, solvents, acids,
caustics, cleaning bath
sludges, batteries
Fly ash, slag, tube
cleanout material, chemical
additives, oil, empty
containers
Chemical additives, empty
containers, cooling tower
bottom sediment
Information
5.2.3 Plant Survey Methods and Procedures
The specific information collected during the audit is
shown in Table 5-4 (8, 10, 14).
To identify missing or inaccurate information, a prelimi-
nary review of the data should be done during, or imme-
diately following, the survey. In addition, survey results
should be converted into a pollution release inventory
using direct measurements, mass balance, and engi-
.neering calculations (11). Sources of information that
may be useful in completing the waste audit include
1) purchasing records, 2) MSDSs, and 3) physical
inventories (9).
At the end of the background information stage of the
waste audit and the plant survey, the waste audit team
should have the following information about each waste
stream:
Material delivery
and storage
Production
processes
Waste
Management
Material transfer and handling
procedures
Material storage procedures
Evidence of leaks or spills
Inventory of materials
Condition of pipes, pumps, tanks, valves,
and storage/delivery area
Exact sources of all process
wastes
Waste flow/quantity and concentration
Operational procedures
Source, quantity, and concentration of
intermittent waste streams (e.g., cleaning,
batch dumps)
Condition of all process equipment
including tanks, pumps, pipes, and valves
Evidence of leaks or spills
Maintenance procedures and schedule
Potential sources of leaks and spills
Operational procedures for waste treatment
units
Quantity and concentration of all treated
wastes and residues
Waste handling procedures
Efficiency of waste treatment units
Waste stream mixing
• Point of origin
• Subsequent handling/treatment/disposal
• Physical and chemical characteristics
• Quantity
• Rate of generation (i.e., pounds per unit of product)
• Variations in generation rate
• Potential for contamination or upset
• Cost for management and disposal
5.2.4 Evaluation and Selection of Waste
Reduction Techniques
Following completion of the waste audit, the next step
is to evaluate the information collected and to use that
information to select appropriate waste reduction tech-
niques. Procedures used to identify, evaluate, and select
applicable waste reduction techniques should:
• List waste streams.
• Identify potential waste reduction techniques for each
waste stream.
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Table 5-4. Information Collected During an Audit
Area o( Facility Type of Information
General General facility layout, indicating proper
facility design
Receiving areas Waste packaging materials and handling of
(toadlng docks, these materials
pipelines) Off-specification or obsolete materials
Spill residues on floor or ground
Proper spill containment equipment
(e.g., shop vacuum)
Proper spill containment supplies
(e.g.. absorbent powder)
Unprotected parking lot drains near loading
dock
Raw material Obsolete materials
warehouse Unnecessary duplication
Intermediate bulk containers (IBCs) instead
of bags and drums
Processing floor Equipment operations audit protocol
Segregation and collection of reusable
waste (e.g., rags)
Equipment condition (maintenance)
Proper equipment operation
Processes for which less-polluting
alternatives exist
Leaks from machines and spills of
processing baths
Leaks from pumps, pipes, and valves
Damaged and leaking containers
Cleaning practices for machines
Dry capture of spills (versus washing spills
down the drain with a hose)
Discards of excess or off-specification
processing solutions
Proper flow control on washers and cooling
water
Running hoses
Process controls and sensors:
• Condition and maintenance
• Obsolescence
• Use and effectiveness
Possible improvements in process step
separations (high extraction, low carryover)
Mix kitchens, Chemical for which less-polluting
drug rooms alternatives exist (e.g., metal-bearing
reducing agents)
Leaking pumps, pipes, and valves
Damaged and leaking containers
• Evaluate the technical and economic aspects of each
technique.
* Select the most cost-effective waste reduction tech-
nique® for each waste stream.
In addition to the above procedures designed to address
specific waste streams, procedures should also be de-
veloped to address facilitywide waste reduction meth-
Area of Facility Type of Information
Mix kitchens,
drug rooms
(continued)
In-process
goods storage
Shop
Offices
Scheduling
department
Laboratory
Power plant,
boilers, raw
water treatment,
air handling
Discussion with
line supervisors
Cleaning practices for implements and mix
tanks
Dry capture of spills (versus washing spills
down the drain with a hose)
Discards of excess or off-specification
processing solutions
Optimized chemical handling practices and
worker attitudes
Collection of reusable waste (e.g., seam,
. sewing waste)
Solvents and cleaners in use
Disposal practices for:
• Spent cleaning materials and sludges
• Lubricating oils
• Batteries
• Machine waste and scrap metal
Equipment maintenance audit protocol
Segregation and collection of reusable
waste (e.g., paper)
Protocol for process equipment scheduling
Incoming process raw material QC protocol:
• Specialty and commodity chemicals
• Fiber, yarn, or fabric
Incoming nonprocess/nonshop chemicals
testing protocol
Sampling practices for incoming material
evaluation
Use of standard tests and reporting
Ash disposal methods
Boiler stack testing previously done
Boiler tub cleanout materials
Boiler chemical use and disposal
Boiler chemical packaging disposal
Proper disposal of filter backwash
Air washer additives use, disposal, and
packaging
Air washer tower bottom sediment
Is schedule appropriate to minimize
machine cleaning?
Is preventive maintenance adequate?
ods (i.e., materials handling, maintenance, and operat-
ing procedures).
5.2.4.1 Technical Feasibility
Following identification of waste reduction procedures,
the next step is to evaluate the technical feasibility of
each technique. This evaluation should consider:
• Applicability
• Waste reduction potential
• Operation and maintenance requirements
234
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• Safety and health
• Ease of implementation
• Reliability
• Special design considerations
5.2.4.2 Risks and Liabilities of Waste
Minimization
These feasibility considerations are not all equally im-
portant. The team leader must determine which factors
should receive special consideration. An important part
of the evaluation process is to consider the risks and
liabilities associated with managing each waste stream.
Therefore, one criterion for judging the relative impor-
tance of each factor is the liability associated with that
factor. Figure 5-4 provides a hierarchical view of the
liabilities associated with each waste minimization
category.
Greatest Liability
Offsiie Recovery
Interindustry Exchange
Onsite Recovery and Reuse
In-Process Recovery and Reuse
Production Process Modification
Inventory Management
Least Liability
Figure 5-4. Waste reduction heirarchy (8).
5.2.4.3 Economic Analysis
In addition to the technical analysis, the team should
conduct an economic analysis of each reduction tech-
nique. Costs to consider include implementation costs
(i.e., capital, installation, operating, and maintenance)
and cost savings resulting from lower production and
waste management/disposal costs. These costs can be
used in a return on investment analysis to calculate the
payback period. Current waste management costs are
very important to consider. These costs include the cost
of shipping waste off site as well as the onsite costs of
labor and time required to handle, manage, track, store,
treat, and manifest the waste. Other costs to consider
include liability insurance premiums, long-term liability
and legal costs, worker health and safety, community
relations, and regulatory compliance.
In combination, the technical and economic analyses
allow selection of the best waste minimization options.
After identification of the options, an implementation
plan should be developed for each waste stream. The
implementation plan should include the implementation
schedule, equipment needs, conceptual design, impte-
mentation requirements, and cost estimates.
5.2.5 Waste Minimization Program
Implementation and Monitoring
The waste minimization program comprises waste
stream reduction plans and general facility recommen-
dations. For the program to be successful, procedures
must be established for monitoring and evaluating the
techniques once they are in place. Also, the program
should allow for development and implementation of
new waste reduction techniques. Important points about
waste minimization programs include:
• Program implementation can be handled in many dif-
ferent ways. Waste streams that present problems or
areas where the investment will have a rapid payback
period should be addressed first. Simple and low-cost
techniques also should be implemented quickly.
• Keeping employees informed during development
and implementation stages is essential. They will be
helpful in evaluating program performance and deter-
mining ways to improve the program.
• Developing a recordkeeping system to track the ef-
fectiveness of each segment of the program is also
important. This allows a comparison of generation
and reduction data over time. Economic data can be
used to determine the efficiency of waste stream re-
duction techniques.
• Corporate commitment is crucial. The program must
be an integral part of the firm's corporate policy, and
a senior-level person should have the authority and
resources to develop, operate, and monitor the
program.
• Some firms have adopted incentive programs to en-
courage the success of their waste reduction pro-
grams. These incentives include:
- A corporate-level waste reduction engineering
group to provide technical assistance.
- Awards and financial incentives for new ideas and
innovations.
- Annual audits.
- A companywide information exchange (e.g., bulle-
tins, newsletters).
— Separate capital expenditure review processes for
waste minimization projects (results in less paper-
work and a quicker review process).
5.2.6 Air Inventory
Although the foregoing waste audit procedures are gen-
eral in nature, the authors who developed them primarily
focused on solid and liquid wastes. Recently, air emis-
sions have received additional attention. This section
235
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describes pollution prevention audit information that fo-
cuses mainly on air issues (15).
Unlike data on water, solid, and hazardous waste, com-
prehensive air inventory data are not readily available,
and analytical methods and sampling procedures for air
toxics are much more difficult than for other types of
waste. Also, unlike water testing, air testing generally
focuses on specific compounds listed as hazardous air
pollutants (HAPs) or toxic air pollutants (TAPs).4 This
complicates the process of auditing air emissions.
The basic concept involved in air testing is similar to that
described above: identify sources, then quantify the
waste from them (15). The required methodology is
quite different, however. Some of the more important
methods are:
• Source tests
• Continuous emissions monitors
• Mass balance calculations
• Emissions factors
• Engineering estimates
The audit must include point sources, area sources, and
fugitive emissions (15). Fugitive emissions are difficult
to estimate because of the difficulties inherent in captur-
ing a representative sample for testing as well as diffi-
culties in determining flow rates. A high percentage of
textile emissions comprise fugitive emissions (15).
An accurate inventory requires expertise in air sampling
and testing as well as a thorough knowledge of textile
operations and textile chemicals (15). Helpful informa-
tion includes:
• MSDSs.
• Material use rates.
• Specific chemical reactions that occur in the process.
• Fuel use rates.
• Temperatures in ovens, steamers, and other similar
equipment.
• Production rates.
• Storage tank information.
• Stack dimensions, air flows, and exit velocities.
• Treatment methods (if any) for air and water.
• Vapor pressures and vapor density of chemicals in
use.
A walkthrough audit is extremely useful for air, just as it
is for other types of waste (15).
4 Further information about specific types of chemicals and tests is
found in Section 2.2.3, Toxic Air Pollutants."
5.2.7 Forms and Lists
Forms and lists have value in that they promote consis-
tent evaluations and organize information in consistent
ways, which helps communicate results (12). Several
forms have been developed to ensure complete and
consistent evaluations, folost pollution situations are
site-specific, however. Therefore, an auditor must al-
ways think and not rely entirely on lists and forms.
5.3 Training Programs and Worker
Attitudes
Training involves instructing a worker about the specifics
of machinery, the facility, and pollution in relation to daily
tasks; effective training is widely recognized as a crucial
ingredient in a good pollution prevention program (8, 9,
12,13,16-20). For short-term improvements, the worker
is an important focus of an effective pollution prevention
program. Short-term successes, in turn, form the foun-
dation for long-term improvements. In short, without
good work practices and worker attitudes, a pollution
prevention program cannot succeed in a labor-intensive
industry such as textiles.
Information concerning general competence of workers
is discussed in Section 3.3, "Enhanced Chemical and
Pollution Prevention Expertise." This section focuses
more on worker-level training as it relates to specific
tasks that affect pollution prevention in daily job per-
formance.
5.3.1 Importance of Training Programs
Pollution prevention training should include all employ-
ees, from the president to the floor sweeper. Of special
importance are employees involved in maintenance,
laboratory, scheduling, design, sales, and other support
functions (8). The cost of training is low: it usually re-
quires no capital investment, and operating costs are
generally minimal (13). Training programs, however, are
one of the highest return low-technology and low-risk
approaches to pollution prevention.
Training has two purposes. One is to inform employees.
The other is to influence employee attitudes with the
goal of making employees more aware of and respon-
sive to pollution prevention. Often, training programs
can be combined because the same type of attitudes
that foster pollution prevention also contribute to im-
proved product quality and employee safety. Training
programs, however, contribute only minimally to shaping
employee attitudes. Other factors must be conducive to
improved attitudes, including:
• Good maintenance of equipment and facilities
• Neat, orderly workplace
• Responsiveness to employee suggestions
236
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Also, as stated in Section 3.3, "Enhanced Chemical and
Pollution Prevention Expertise," employee suggestions
should be solicited and acted upon (9). Nothing stops
employee involvement in a program faster than failure
to act on comments and suggestions.
5.3.2 Information To Include in Worker
Training
Richardson and others suggest that the information be-
low be included in worker training (9). This information
should be presented from the worker's point of view and
within the worker's frame of reference. The credibility of
the training program sets the tone for the employee
pollution prevention effort.
An attitude-oriented training approach should include
the following information:
• Company policy.
• Goals.
• Priorities.
« Importance of policies, goals, and priorities.
• The effect waste has on the environment.
• Sources of waste.
• The effect employee actions have on the environment.
• The effect of waste on profits and employee success.
* Importance of right-first-time production.
• Detrimental effects of poor housekeeping and
maintenance.
• What is expected of employees.
• What employees can expect from management.
• What employees will gain in return.
An information-oriented training approach should in-
clude the following information:
• How the process works chemically and physically
• How and why processes produce waste
• Specific instructions concerning waste reduction
This document provides useful, general information for
training programs. Site-specific and job-specific infor-
mation must be added, however, to complete the nec-
essary information package for a good training program.
5.4 Technology Transfer
The adoption of proven, successful pollution prevention
technology is one of the most cost-effective ways to deal
with environmental protection. The easiest technology
transfer activities involve adoption of methods from simi-
lar operations. Adopting methods from different opera-
tions within the same industry is slightly more complex
and less certain. The least certain, and most energy-
and time-consuming, is the adoption of known, proven
technologies from other industries. Overall, however,
technology transfer is a sure way to obtain positive
results with minimal investment of time and resources.
This is especially true for smaller and less sophisticated
operations.
A company that can pursue a large R&D effort or can
make large capital investments can reasonably expect
to achieve pollution prevention by investigating new
technology and new science or by replacing equipment
and developing new processes. That is an appropriate
long-term activity. Technology transfer is extremely valu-
able, however, to smaller mills (and to larger mills as
well) in building a framework for a pollution prevention
program. The implementation of known technologies
such as orderly work practices, optimization of proc-
esses, and training is fundamental to any good pollution
prevention program, large or small (20).
Helpful sources of information for pollution prevention
technologies include:
• State pollution prevention offices
• Compendia of case histories
• Pollution prevention libraries
• Trade associations
* Trade publications
Table 5-5 provides a brief list of the types of information
that can be easily found.
Table 5-5. Sources of Case Study Information on Pollution
Prevention in Textiles
Source Document/List
Accomplishments of North
Carolina Industries
Leaders in Hazardous Waste
Reduction
Managing and Recycling
Solvents
Pollution Prevention Case
Studies
Case Studies of Waste
Reduction
Number
of Cases
55
16
12
34
64
References
NCDEM (1987)a
NCDEM.{1990)
NCSUCOE (1986)b
NCDEM (1993)
WRRC (1989)°
Profits of Pollution Prevention 25 NCDEM (1985)
Handbook for Using a Waste 10 NCDEM (1991)
Reduction Approach To Meet
Aquatic Tbxicity Limits
a NCDEM = North Carolina Division of Environmental Management,
3825 Barrett Drive, Raleigh, NC 27611.
NCSUCOE = North Carolina State University College of Engineer-
ing, Raleigh, NC 27695.
0 WRRC = Waste Reduction Resource Center for the Southeast; 3825
Barrett Drive, Raleigh, NC 27611.
237
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In addition, several states and industry trade groups
have established programs to educate textile retirees in
the techniques of pollution prevention and then place the
retirees in mills to consult on pollution prevention plan-
ning and implementation. These programs provide a
valuable resource for onsite study and consultation.
5.5 References
1. Baker, G.E. 1995. Pollution prevention and total quality manage-
ment. In: Freeman, H.M., ed. Industrial pollution prevention hand-
book. New York, NY: McGraw-Hill.
2. Wells, R.P., M.N. Hochman, and S.D. Hochman. 1994. Introduc-
tion to total quality environmental management. Cambridge, MA:
Abt Associates, Inc.
3. Case, L, L Mendicino, and D. Thomas. 1995. Developing and
maintaining a pollution prevention program. In: Freeman, H.M.,
ed. Industrial pollution prevention handbook. New York, NY:
McGraw-Hill.
4. Minnesota Office of Waste Management. 1991. Minnesota guide
to pollution prevention planning. Minnesota Office of Waste Man-
agement, Minneapolis, MN.
5. Pojasek, R.B., and L.J. Call 1991. Contrasting approaches to
. pollution prevention. Pollution Prevention Review (Summer), p. 230.
6. Evers, D.P. 1991. Facility pollution prevention planning. In: Free-
man, H.M., ed. Industrial pollution prevention handbook. New
York, NY: McGraw-Hill.
7. Calfa, L, J. Hdbrook, C. Keenan, and T. Reilly. 1993. A guide to
pollution prevention in woolen mills (Capstone Project). Prepared
for Northern Textile Association (July).
8. Hunt, G.E. 1989. Developing and implementing a waste reduc-
tion program. North Carolina Department of Environment, Health
and Natural Resources, Pollution Prevention Program, Raleigh,
NC (May).
9. Richardson, S. 1991. Multimedia environmental concerns in warp
sizing: Low tech approaches to waste reduction. North Carolina
Pollution Prevention Program, Raleigh, NC (February).
10. Smith, B. 1986. Identification and reduction of pollution sources
in textile wet processing. North Carolina Department of Natural
Resources and Community Development, Pollution Prevention
Pays Program, Raleigh, NC.
11. U.S. EPA. 1988. Estimating chemical releases from textile dyeing.
EPA/560/4-88/004h. Washington, DC (February).
12. Holme, 1.1992. Collaboration is the key to success. Textile World
(November), p. 33.
13. Hollod, G.J., and R.F. McCartney. 1988. Waste reduction in the
chemical industry: DuPonfs approach. E.I. du Pont de Nemours
and Company, Inc. (February).
14. Richardson, G.A. 1990. Are textiles finishing the environment: A
case study. Textile Institute Finishing Group Conference, Man-
chester, England (May 8).
15. McCune, E.G. 1993. Emissions inventory for textile operations.
Presented at the Conference for Executives and Managers on
Environmental Issues Affecting the Textile Industry, Charlotte, NC
(June 14-15). Environmental Policy and Studies Center, Hickory,
NC, and North Carolina Department of Environment, Health and
Natural Resources, Raleigh, NC.
16. Nagar, A.M. 1985. Optimum utilization of lubricants in textile mills.
The Indian Textile J. (December), p. 83.
17. Provost, J.R. 1992. Effluent improvement by source reduction
of chemicals used in textile printing. Textile Horizons (May/June).
p. 260.
18. Duffield et al. 1990. Duffield, P.A., J.M. Wimbush, and P.F.A.
Demot. 1989. Wool dyeing with environmentally acceptable lev-
els of chromium in effluent. International Wool Secretariat (IWS)
Development Center Monograph. IWS, West Yorkshire, England.
19. Glover, B., and L. Hill. 1993. Waste minimization in the dyehouse.
Textile Chem. and Colorist (June), p. 15.
20. Smith, B. 1992. Source reduction: Alternative to costly waste
treatment. Amer. Textiles Int. (ATI) (March).
238
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Chapters
Pollution Prevention Incentives and Overcoming Barriers
to Pollution Prevention
The business realities of the textile industry sometimes
cause companies to shift their focus away-from pollution
prevention. Today, textiles is an extremely fragmented
and competitive business, subject to cyclical business
trends. When demand is high for textile products, com-
panies tend to focus on production volume above all
else. When demand is low, capital-intensive activities
such as equipment replacement and modernization are
restricted, to the detriment of pollution prevention pro-
grams. In addition to the general and specific pollution
prevention methods presented in Chapters 3 and 4,
therefore, this chapter addresses the business consid-
erations of pollution prevention.
In some cases, these business considerations take the
form of barriers between customers and suppliers; in
other cases, the considerations create internal barriers.
Both types of barriers are discussed below.
6.1 The Need for Integration
One major barrier to pollution prevention in textile op-
erations is the lack of integration in the.1 textile industry.
Textiles typically are shipped from one facility to another
as they progress from raw material production stages
through spinning, weaving, knitting, preparation, finish-
ing, and cut and sew. This segregated industry structure
is the source of an enormous diversity of capabilities that
exist to satisfy the ever-changing needs of the apparel,
furnishings, and textile specialties markets. At each
processing stage, however, pollutants that were added
at upstream (i.e., previous) operations may be removed,
while others, with the potential to cause pollution in
downstream facilities, may be added.
Textile facilities often lack the ability to influence produc-
tion methods used at upstream facilities. Likewise, they
have little incentive to change their own operations to
reduce pollution at downstream facilities. The lack of
integration in the industry means that opportunities to
reduce pollution fail to be acted upon. Pollution prob-
lems caused at upstream facilities are accepted as a fact
of life and textile managers concentrate on meeting
orders, satisfying customer requirements, and staying
competitive, not minimizing pollution at someone else's
facility.
Current trends may benefit pollution prevention efforts,
even among facilities that normally do not concern them-
selves with each other's operations. During the 1980s,
the importance of customer-supplier relationships came
to the forefront of U.S. manufacturing. Largely because
of the emergence of concepts such as total quality
management (TQM), just-in-time manufacturing, elec-
tronic data interchange, and ISO 9000 standards, cus-
tomers began talking more frequently with their
suppliers about issues of joint concern. Now that these
lines of communication are open, these relationships
with customers need to be expanded to support pollution
prevention. Several current developments appear to
provide the incentive for this growth.
6.1.1 ISO 14000 Environmental Standards
The ISO 9QOO certification process provides a means for
companies to ensure that their suppliers adhere to rec-
ognized quality management standards and have in
place a sound quality management program. Even com-
panies that have not pursued the rigors of ISO 9000
certification have embraced quality management and
implemented TQM programs at their facilities. In the
1990s, many expect a TQM-type movement to develop
with respect to companies' environmental management
systems. As of this writing, a technical committee of the
International Organization for Standardization (ISO) is
overseeing the development of the ISO 14000 series of
standards, which will be patterned after ISO 9000. ISO
14000 is on a fast-track development schedule and is
expected to be released in 1996.
The ISO 14000 standards will focus on environmental
management, rather than environmental performance.
The standards will define the features of an environ-
mental management system (EMS) that need to be in
place to ensure that companies identify and focus on
improving areas where they have significant environ-
mental impacts. The idea is that if the correct type of
management system is in place, performance will follow.
Additional specifications in the 14000-series will cover
239
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environmental auditing, environmental labeling, envi-
ronmental performance evaluation, life-cycle assess-
ment, and product standards (1).
ISO 14000 certification could provide the basis for as-
sessing supplier conformity with recognized standards
for environmental management and for demonstrating a
company's commitment to being a good "environmental
citizen." This certification will provide a basis for com-
paring suppliers and vendors of products (2). This rep-
resents a departure from the previous emphasis on
regulatory means for environmental protection (3). The
variations in regulations that exist from one country or
region to another are a major drawback to the regulatory
approach (4). ISO 14000 is expected to provide an
equitable, impartial basis for supplier relationships and
certification, as well as for international environmental
protection (4, 5). The standards of ISO 14000 are ex-
pected to consider not only the environmental factors
involved but also the way business is conducted, hope-
fully without creating trade barriers (2,3). IS014000 will
also provide advantages in the area of economic returns
and liability control.
According to preliminary reports, ISO 14000 will set
standards for companies in the following areas (6):
• Developing corporate policy.
• Identifying the environmental consequences of ac-
tions and products.
• Setting clear environmental goals for all activities.
• Implementing environmental programs to achieve
those goals.
• Assigning responsibility for those activities and goals.
• Informing and training employees, suppliers, and
customers.
• Establishing policies and procedures to deal with in-
cidents such as spills.
• Conducting periodic audit and review.
• Ensuring continual improvement of environmental
performance.
ISO 14000 will undoubtedly be adopted first by large,
multinational firms doing business in environmentally
sensitive European markets. The crucial determinant of
how effective ISO 14000 will become is not whether it
will be adopted by manufacturers, but how effectively it
will be adopted by customers as a certification tool for
suppliers. If this practice becomes widespread, textile
facilities may find themselves being asked about meas-
ures they are taking to reduce pollution related both to
their own operations as well as to upstream and down-
stream operations.
6.1.2 Other Initiatives
An organization of European retailers has been formed
to foster cleaner production practices among suppliers,
as assessed by life-cycle analysis. This effort is called
the project for the introduction of ecologically sound
assortments in the retail trade (PRIMA) (7). One focus
of this effort is to accurately identify the environmental
burden associated with various products. This in turn
encourages the development of environmentally im-
proved products in the global sense through manufac-
turing, purchasing, marketing, and consumer demand/
consumption of the product. Technically valid and accu-
rate guidelines for product selection and assessment of
environmental impact have been developed through
close collaboration of manufacturers and retailers. As
noted in Sections 4.16 and 4.17 as well as Chapter 6,
involvement of retailers and consumers is a powerful
pollution prevention factor, especially in view of modern
trends toward demand activated manufacturing and the
impact of design decisions in pollution prevention. An
entity relationship diagram from the retail perspective is
shown in Figure 6-1.
The PRIMA system provides a basis for comparing do-
mestic and import suppliers; this comparison system is
necessary because very different regulatory standards
are often applied to suppliers of similar products. The
system is based on evaluation of consumer prefer-
ences, establishment of purchasing specifications for
environmentally friendly textile products, and identifica-
tion of specific suppliers with superior environmental
practices. The system also specifies the most environ-
mentally benign manufacturing processes for a given
retail product. Environmental and economic conse-
Consumers
Growing environmental
awareness
Government
Environmental directives
for companies products,
substances, and waste
streams
Consumer demand
Government policies
t
Retailers
Environmental
Improvement of Retail
Assortments (EIRA)
Product supply
1
Suppliers
Environmental
Improvement of products
and processes
i
Figure 6-1. An entity relationship diagram from the retail per-
spective (7).
240
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quences of various retailing policies are analyzed, and
comparison of all data allow the retailer and designer to
make informed choices about the optimum allocation of
resources.
6.2 Business Opportunities and
Pollution Prevention Needs
A good pollution prevention program should identify and
exploit the market opportunities associated with pollu-
tion prevention. These opportunities, if properly pur-
sued, not only offset the costs of pollution prevention but
can lead to new business opportunities. Many compa-
nies have discovered new business opportunities as a
result of their efforts to solve pollution problems. This
section discusses only two of the most obvious oppor-
tunities relevant to the textile industry: the sale of waste
by-products and the promotion of "green" or environ-
mentally friendly products.
6.2.1 Marketing of Waste By-Products
Wastes are an unavoidable by-product of any manu-
facturing process, and many textile processes pro-
duce high volumes of waste. The term waste usually
implies something without value, something that can-
not be used or reused for any worthwhile purpose and
that is typically discarded. Increasingly, though, com-
panies are finding that their wastes do have value and
can ,be reused in manufacturing processes, either
within their own operations or by another firm. The
sale of waste by-products from a textile operation
represents a significant business opportunity that can
produce income and also eliminate the costs associ-
ated with waste disposal.
Although waste by-product sale or reuse is gaining
prominence in the textile industry, certain business and
technical barriers restrict market opportunities. First, the
value of most waste by-products is almost always less
than that of the primary products. The sales incentive is
therefore low for these by-products, and companies can
easily lose sight of the fact that collecting and selling
wastes can be a profitable venture. A further reason that
wastes are undervalued is that companies may not fully
account for the costs of collection and disposal, as well
as the potential liability associated with some wastes.
When the costs of managing these wastes are consid-
ered, the sale of waste products may become substan-
tially more profitable.
Technical barriers also restrict the sale of waste by-prod-
ucts. For quality and safety reasons, many companies
are reluctant to buy waste materials for use as raw
materials. With so many disincentives, companies may
overlook valuable opportunities, based on generalized,
and often uninformed, business views eibout marketing
wastes. Markets for industrial waste by-products are
constantly improving, however, and more companies
are considering potential waste reuse opportunities.
Some research arid development work may be neces-
sary, however, to demonstrate the potential viability of
new reuse applications.
6.2.2 Consumer Information
f
In addition to highlighting the potential value of waste
by-products, a well-designed pollution prevention pro-
gram can produce valuable information about the en-
vironmental impacts of products or processes. If
properly presented, information about the environ-
mental friendliness of products or processes can be
used to educate customers, which in turn may influ-
ence their product purchases. According to studies
summarized by Wagner, 70 percent of customers
would choose a product based on environmental con-
siderations if the price were the same, and 30 percent
of customers say they would pay up to 20 percent
extra (8). As this business tactic becomes more popu-
lar, companies increasingly recognize the marketing
advantage of environmentally friendly products. Nu-
merous textile companies have already begun pro-
moting environmentally friendly brand names,
including Burlington's Green Vista, Dyersburg's Eco-
sport, CRI's Green Tag, and others (8).
To use (and recycle) products properly, more information
on use, installation, proper combinations of products,
and inappropriate end-uses should be made available
to consumers. The plastics industry is a good example
of an industry that provides recycling information to
consumers in the form of an easily understood code, to
differentiate among different types of plastics. With tex-
tiles, product information may be important in certain
cases to avoid adverse impacts on indoor air quality and
other environmental concerns.
Although the sale of environmental products is gaining
prominence, these green claims in advertising need to
be kept in perspective. Sales and advertising depart-
ments, either deliberately or through lack of knowledge,
may make incorrect, misleading, or improper claims for
products. This does little to inform the public about
textiles and environmental issues, and may hurt the
company's image or reputation. Some have cast doubt
on the objectivity of environmental claims made in clever
advertising and marketing strategies (9). This issue,
which depends largely on the communication between
those responsible for the technical and marketing areas,
is further discussed in Section 3.13, "Disinformation
About Environmental Issues."
6.3 Priorities and Commitments
Upper management normally controls the resources
needed to develop and operate a pollution prevention
241
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program. Commitment from upper management, there-
fore, is essential for a successful program (10). The first
step in any pollution prevention program, and perhaps
the most important, is to convince management of the
importance of pollution prevention as a better way of
doing business. Regulatory consequences, as well as
cost and liability of waste, are major business consid-
erations and are often the driving force that causes
management to consider pollution prevention as a busi-
ness strategy. Reducing waste inherently increases raw
material utilization and process efficiency, and thus in-
creases profits. In addition, regulation of waste entails
enormous complexity and sometimes liability for waste
generators, making waste minimization and pollution
prevention the preferred business strategy (11).
To clearly establish management commitment, the first
step in a pollution prevention program should be to
establish pollution prevention as a clear corporate pol-
icy. The Textile Finisher's Association (United Kingdom)
understood the need for recognition and commitment by
upper management and formed a task force under a
senior manager. This idea was endorsed, stating that
"Commitment by senior management... was essential
to ensure action" (12). Undoubtedly, many pollution pre-
vention program managers throughout industry would
echo this same sentiment.
After establishing corporate commitment, the pollution
prevention program can expand to include an imple-
mentation schedule, conceptual design, identification of
equipment needs, and cost estimates. Some companies
have streamlined paperwork and other procedures re-
lated to pollution prevention expenditures, thus acceler-
ating the implementation process (13). A good pollution
prevention corporate policy should be formalized (writ-
ten) and easy to understand, and should set achievable
goals for management as well as for production workers
and supervisors (14).
Most pollution prevention project initiatives show a sub-
stantial initial payback and lead to increased profits
because ideas that produce the highest payback and
cost the least are generally implemented first (13). Man-
agement must also accept, however, the fact that as
time passes, a rigorous pollution prevention program will
mean some fundamental changes in the way the com-
pany conducts business. Another important fact to rec-
ognize is that even in a modest-sized plant, the effort
required to carry out successful pollution prevention
programs is significant (10).
Regulatory pollution prevention programs are becoming
more common. Hollod and McCartney (11) and other
authors, however, have warned that regulatory pollution
prevention programs are counterproductive because
they may define waste reduction too narrowly and
thereby lead to decreased (not increased) industry ef-
forts. Industry has responded well to the pollution pre-
vention challenge and has established a clear commit-
ment without regulatory pollution prevention.
Further information on implementation can be found in
Chapter 5, "Implementation of a Pollution Prevention
Program."
6.4 Conflicting Goals
In business, conflicting goals often arise that make
choosing among competing alternatives difficult. Pollu-
tion prevention is no exception. Usually, economic gain
and pollution prevention go hand in hand because high
processing efficiency and low waste are compatible
goals. Also, worker attitudes that promote pollution pre-
vention are compatible with product quality. Occasion-
ally, however, these goals may conflict, resulting in
conditions that can hamper pollution prevention efforts
unless identified and resolved. Most of these conflicts
are caused by policy, not technical, issues, including:
• Water conservation.
• Low biological oxygen demand (BOD) versus pass-
through aquatic toxicity.
• Dye stability versus treatability.
• Quality considerations and high-value products.
• Proprietary issues.
• Segregation and capture versus disposal facilities.
• Cost.
• Marketing.
6.4.1 Water Conservation
In most municipalities, industrial sewer users pay a fee
for sewer use based on a formula that includes water
volume, BOD, total suspended solids (TSS), and other
factors. Typical values for textile waste are (15):
• Water =15 gallons per pound of production
• BOD = 400 parts per million (ppm)
• TSS = 25 ppm
Usually, the BOD fee is expressed as a particular
amount (typically $0.25 to $0.50) per pound of BOD over
a certain base concentration limit (typically 250 to 300
ppm). When water use decreases, the (constant) num-
ber of pounds of BOD is contained in less water, simul-
taneously raising the BOD concentration. Publicly
owned treatment works (POTWs) surcharge formulas
are usually written so that the cost savings resulting from
water reduction are partially—and sometimes even
fully—offset by an increased BOD surcharge. The rea-
son for the increased surcharge is to defray additional
operating costs because of the excess cost of treating
high BOD wastewater.
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Municipalities often use the above reasoning to con-
vince mills to build expensive pretreatment facilities. In
most cases, textile wastes are low in TSS but high in
BOD, typically 25 ppm TSS and 400 ppm BOD before
pretreatment (15). Pretreatment converts some of the
BOD into suspended solids (biomass), thereby decreas-
ing BOD but increasing the amount of TSS sent to the
POTW. The net result is that the POTW still has to
dispose of the same amount of sludge, and operating
costs do not decrease. In essence, pretreatment at the
textile mill does not accomplish anything. Municipalities
should rethink this jssue and not penalize mills for water
conservation.
Holme (12) reports a significant U.K. study of water
conservation by the Textile Finisher's Association, which
concluded that water conservation would lead to higher
pollutant concentrations in wastewater, and thus a revi-
sion of pollutant loading limits would be appropri-
ate (12). Similar examples have been cited elsewhere
(1.6).
6.4,2 Low BOD Versus Pass-Through
Aquatic Toxicity
Selecting chemical specialties with the lowest possible
BOD values also can reduce BOD. This leads to lower
BOD in the effluent and thus reduces the sewer sur-
charge. As described in Sections 2.2.6, "Aquatic Toxic-
ity," and 4.4, "Chemical Specialties," chemical
specialties are the most likely to pass through POTWs
and result in aquatic toxicity. The structure of POTW
surcharges in many cases encourages mills to make
undesirable substitutions of nondegradable/low-BOD
surfactants, which pass through treatment systems and
increase aquatic toxicity in the treated effluent.
6.4.3 Dye Stability Versus Treatability
Consumers have demanded dye and printed fabrics
with more permanent color, so the texlile industry has
provided them. Dyes are now resistant to all manner of
environmental agents (e.g., water, light, solvents, rub-
bing). In the process of becoming more permanent,
however, dyes have also become resistant to treatment
and now tend to pass through waste treatment systems,
producing aesthetically undesirable color pollution in the
receiving waters. Although generally harmless, the color
pollution is highly visible and is becoming an increasing
focus of regulatory agencies. Treatment systems often
degrade resistant dyes, using chlorine and other agents,
into colorless, though more harmful, materials.
6.4.4 Quality Considerations and High-Value
Products
Pollution prevention tends to be most cost-effective
wherever processing efficiency is most directly linked to
the firm's bottom line. This includes most high-volume
textile products, such as sheeting and denim. For a few
special products, however, profitability depends almost
exclusively upon product quality or exceptional styling
and marketing. In these product markets, the cost of
waste and waste management is relatively insignificant,
and the economic incentives for reducing waste or pol-
lution are not nearly as significant. Examples include
very high-value products, such as coated fabrics for
offset printing, blankets, or papermaking felts. These
products sell for extremely high prices in relation to the
raw material costs, and quality requirements are excep-
tionally rigid.
The potential loss of value because of off-quality product
or seconds that may result when converting to alternate
technologies is great, and waste raw materials have
essentially no value compared with the product. These
conditions make it difficult to convince a manufacturer
to focus much attention on substituting raw materials,
modifying processes, and changing designs or specifi-
cations on an already successful product. Because of
the lack of economic incentive, progress on pollution
prevention is slower in these market segments.
6.4.5 Proprietary Issues
Many chemical and dye suppliers attempt to keep the
chemical nature and composition of materials secret,
although the products they offer often are quite similar
upon analysis. Nonetheless, this commercial desire for
secrecy as a competitive tool creates a significant prob-
lem for the textile processor, who needs to know the
chemicals being used in the process in order to imple-
ment pollution prevention measures.
This problem is increasing as some of the largest, most
reputable companies adopt secrecy tactics. In addition,
the large dyestuff companies are abandoning the Colour
Index, a widely used listing of generic dyestuffs. This will
further contribute to the lack of information and will make
evaluating chemical and dye substitution possibilities
more difficult and more expensive. Lack of information
about chemical compositions makes substitution evalu-
ations, especially for air and aquatic toxicity concerns,
difficult or impossible. This, combined with the fact that
the structure of POTW charges and regulatory adminis-
trative measures often punishes technically correct sub-
stitutions, often leads to poor decisions by chemical and
dye suppliers.
6.4.6 Segregation and Capture Versus
Disposal Facilities
Another example of conflicting goals occurs in waste
segregation and capture. Some technologies exist that
facilitate separation and capture of hazardous constitu-
ents in wastewater, thereby keeping them out of the
effluent stream. If disposal of these captured hazardous
concentrated wastes is illegal (which is often the case),
243
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however, then the processor has little incentive to treat
the waste. Keeping hazardous waste out of sewers is
often desirable but not rewarded.
6.4.7 Cost
Cost accounting practices for textile operations (and
manufacturing operations in general) often fail to reward
pollution prevention activities. Waste treatment and dis-
posal costs (as well as liability) are usually considered
part of overhead and are almost never allocated to the
unit processes actually responsible for them.
For example, a reduction in the use of knitting oil at a
knitting mill, which reduces BOD in the knit scouring
and dyeing operation, will usually not be rewarded
because no link is made between waste treatment
costs and the use of knitting oil in the knit operations.
This is a purely business, not technical, matter. The
issue is discussed further in other chapters of this
document, and substantial literature exists in the en-
vironmental management field that discusses this
problem and ways to address it.
6.4.8 Marketing
Environmental protection sometimes increases pro-
duction costs, which increases consumer costs. In
some cases, product lines must be discontinued and
are no longer available to the public. In one case, a
manufacturer withdrew a flame retardant cotton fabric
line from the market because the high cost of produc-
tion resulted in a market price that was no longer
competitive (17).
6.5 Risk Assessment Methods, Data,
and Procedures
Many pollution prevention techniques described in this
document involve tradeoffs in risk, so when mills evalu-
ate pollution prevention techniques, they must account
for the risks associated with those techniques.1 To make
reasonable risk/benefit assessments, three elements
are required:
• One must be able to quantify the risk (by quantifying
the exposure or concentrations present) and the haz-
ard (i.e., the ability of the waste to damage the envi-
ronment).
• One must be able to quantify the benefit.
• One must be willing to somehow trade off, replace,
equate, substitute, or exchange some amount of risk
for some amount of benefit.
If any one of these three is missing, the risk/benefit
analysis will be flawed and pollution prevention deci-
sions may be less than optimal.
6.5.1 Tradeoffs in Benefits and Risk
Several categories of waste were cited in Chapter 2,
"Waste Categories for Pollution Prevention," including
Table 6-1. Waste Hazards and Exposure Potentials
Type
Dispersable
Hard-to-treat
Offensive
High-volume
Hazard
Varies
Varies
Very high
Varies
Exposure
Potential
Very high
Very high
Varies
Very high
1 This section requires an understanding of three key terms: risk,
hazard, and exposure. Risk is an exposure to a hazard. Hazard is
tha discharge of a material to the environment in such a way that it
can affect a susceptible site (place where it can do harm). Exposure
is tha lave) or concentration of the material that is present at the
susceptible site.
dispersable, hard-to-treat, offensive, and high-volume
wastes. Table 6-1 evaluates the risks associated with
each type of waste:
• Highly dispersable wastes: Are likely to become wide-
spread in the environment and present greater po-
tential for exposure, albeit at lower concentrations if
they become diluted in the process. Because these
wastes are at some point well contained within the
textile processing operation, the cost of preventing
dispersion (and reducing risk) is generally less than
the cost of treatment once the waste has been dis-
persed over a large area. This is especially true for
wastes that are hazardous at low concentration or
that are persistent or bioaccumulative.
• Hard-to-treat wastes: Tend to interfere with or pass
through waste systems. The cost of treatment is thus
relatively high, while avoidance through pollution pre-
vention techniques is often fairly inexpensive. The
main techniques for avoiding these wastes are
chemical substitution and process changes.
• Offensive wastes: Are hazardous and can do rela-
tively significant damage if released; require great
care in storage and handling, spill control, auditing,
and treatment. The risk of these materials can be
reduced by substituting less-offensive (less-hazard-
ous) materials, which do not pose similar threats.
• High-volume wastes: Can be costly to treat and dis-
pose of because of the large amounts of material that
require handling. In many cases, the raw materials
have relatively low unit costs to treat and/or dispose
of, but are present in such large amounts that their
total costs are substantial. In addition, the costs of
collection, transportation, and disposal, as well as the
liabilities associated with these wastes, represent a
244
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significant risk to the manufacturer. Pollution preven-
tion, especially reuse and recycling, reduces these
costs and liabilities and conserves raw materials that
can be saved and reused in textile processing opera-
tions.
Controlling these wastes by treatment is usually more
expensive than controlling the hazard or exposure
using a pollution prevention approach. Each pollution
prevention technique described in this document fo-
cuses on one of the three elements listed below (see
Table 6-2). Each pollution prevention technique is de-
signed to help:
• Quantify hazards or exposures and, therefore, risks
• Quantify benefits
• Evaluate tradeoffs between risks and benefits
Although the information contained in Table 6-2 is basic,
it provides a framework for thinking about pollution pre-
vention that can be useful in textile operations, espe-
cially when designing, implementing, and evaluating a
pollution prevention program.
Table 6-2. Control Points for Pollution Prevention Techniques
Pollution Prevention Technique Control Point
Design-stage planning
More chemical expertise
Equipment maintenance
Global, integrated view
Chemical alternatives
High extraction
Incoming raw material QC
Nonprocess chemical control
Process alternatives
Material utilization
Optimized chemical handling
Raw material prescreening
Reducing disinformation
Risk assessment methods
Scheduling to minimize cleaning
Standards, tests, and definitions
Consumer information
Technology transfer
Training programs
Waste audit
Segregation and reuse
Improved process control
All
Evaluation, benefits
Release
Evaluation, benefits
Hazard
Release
Hazard
Hazard
Hazard, release, benefits
Release:
Release
Hazard
Evaluation
Evaluation
Release
Evaluation
Evaluation
Evaluation
Evaluation, release
Evaluation, benefits
Release
Release
6.5.2 Barriers: Known Versus Unknown
One barrier to effective pollution prevention is ignorance
or insufficient understanding of one of the three ele-
ments listed above (i.e., risk quantification, benefit quan-
tification, or evaluation of tradeoffs). Training or
consultation with experts can overcome these barriers.
A more difficult barrier to overcome is a lack of informa-
tion on hazards, such as aquatic toxicity of a chemical
or pollutant, or a lack of information about the chemical
constitution of specialty processing assistants (14, 15,
18). If this basic information is missing, hazard evalu-
ation is impossible, making the task of prioritizing pollu-
tion prevention actions more difficult.
In addition, many barriers exist because environmental
burdens are not tied directly to the unit processes that
are actually responsible. For example:
• Warp sizing operations contribute aquatic toxicity and
BOD, which end up in the wastewater of the desizing
operation. The sizing operation, however, does not
participate in the cost of treating this waste.
• End-of-pipeline quality control (QC) fails to allocate
the costs of defective production to specific unit proc-
ess problem areas; rather it serves only as a point to
discard or rework nonconforming production. Most
rework or discard necessitates additional processing
with associated costs, wastes, and waste treatment
and disposal.
• Business policies often view each plant in a frag-
mented industry as a separate profit center, with little
consideration of global issues. This view frustrates
coordination among sites to further overall pollution
prevention goals.
• A lack of standard terminology, tests, and definitions
for even the most fundamental environmental prop-
erties of chemical materials inhibits communications
and proper evaluation.
5.5.3 Overcoming Barriers
To design a good pollution prevention program, barriers
must be overcome. Several efforts to do so are under-
way, and some examples are described below.
Glover and Hill (19) report good results from using com-
puter modelling to evaluate operating costs of global
pollution prevention. Their analysis (see Table 6-3)
shows the relative cost of pollution in the same terms as
other cost factors now in cost systems. This allows more
incisive risk/benefit analysis. In addition, the computer
model allows the effects of quality, energy, and other
factors to be compared on a cost basis. The program
also allows easy quantification of benefits, based on
changes in operational parameters in a textile manufac-
turing operation.
245
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Table 6-3. Computer Simulation of Cost Impacts of Pollution Prevention in Dyeing (10)
Cost Components
Case
Dyes
Energy
Water
Chemicals
Effluent
Total
Basa case*
Exhaust 10:1
Base case + 1
shading addition
Base case + 2
shading additions
Base case + strip
and redye
Continuous:
pad-dry-chem-pad-steam (Vat)
Process: pad-dry-bake
(reactive dye)
Process: pad-batch
(reactive dye)
$43.20
38.4%
$47.52
39.9%
$51.84
41.3%
$86.40
37.8%
$46.98
44.1%
$29.25
34.0%
$31.32
42.3%
$26.23
23.3%
$28.30
23.8%
$30.33
24.2%
$36.45
16.0%
$28.03
26.3%
$29.02
33.8%
$19.48
26.3%
$8.23
7.3%
$8.23
6.9%
$8.23
6.6%
$8.50
3.7%
$6.01
5.6%
$3.65
4.2%
$3.60
4.9%
$26.87
23.9%
$26.87
22.6%
$26.87
21.4%
$86.00
37.7%
$18.43
17.3%
$17.87
20.8%
$13.44
18.2%
$8.00
7.1%
$8.12
6.8%
$8.14
6.5%
$10.98
4.8%
$7.02
6.6%
$6.14
7.1%
$6.12
8.3%
$112.52
100.0%
$119.04
100.0%
$125.41
• 100.0%
$228.33
100.0%
$106.47
100.0%
$85.93
100.0%
$73.96
100.0%
* Basa case * woven 100 percent cotton, singe-desize-scour-bleach-mercerize-stenter dry, 500-kg batch, continuous jet, fiber-reactive dye,
portionwlse addition of salt, washoff three hot rinses, LR 10:1, fixation 70 percent.
Other systems are being developed to assist in the
evaluation of tradeoffs, especially when comparing
chemical systems, process alternatives, or chemical al-
ternatives (20, 21 ).2 In one case, an equation is used to
rate all pollutants in terms of their degradability and
effect on waste treatment systems and to express the
aquatic toxicity of treated effluent as a numerical value.3
Another system ranks four attributes of each chemical
(i.e., toxicity, air emissions, biodegradability, and Re-
source Conservation and Recovery Act [RCRA] status)
(20). Another effort is underway to provide on-line elec-
tronic access via the Internet to a chemical database
that includes all important pollution characteristics of
chemicals, plus their interactions with each other and
with substrates and processes (21). None of these sys-
tems has reached technical commercial perfection, but
each indicates positive progress toward filling the infor-
mation vacuum.
6.6 Human Resources
Much of this document focuses on technical solutions to
pollution prevention. For an effective pollution preven-
tion program, however, employees must have a high
level of understanding of the technical processes and an
awareness of pollution prevention. Developing human
resources is crucial to the success of pollution preven-
tion. In short, a good pollution prevention program goes
Moore, S. 1994. Personal communication between Samuel Moore
of Burlington Research and Brent Smith, Department of Textile
Chemistry, North Carolina State University, Raleigh, NC.
3 See footnote 2.
beyond technical expertise; it requires a high degree of
involvement and commitment on the part of all employ-
ees. This is a "human" approach to pollution prevention
and is quite different from process tweaking, chemical
alternatives, and other technical approaches to pollution
prevention.
6.6.1 Workers and Supervisors
The value of enthusiastic, concerned employees in a
pollution prevention program cannot be overstated.
Some companies successfully use a reward system for
employees who make significant pollution prevention
observations or suggestions (13). By way of example
and incentive, a modest water leak costs as much in 1
year as a week of paid vacation for one worker (14). The
value of developing worker and supervisory expertise
has been described in other chapters of this document,
such as Sections 3.2, "Enhanced Chemical and Pollu-
tion Prevention Expertise," and 5.3, "Training Programs
and Worker Attitudes."
6.6.2 Management and Staff
Morris reports that one company cut its waste almost in
half by adding a full-time environmental manager to the
staff (17). This is not an unusual case. Many companies
now are allocating management and staff positions to
pollution prevention, and these positions usually pay for
themselves in lower waste collection costs, lower dis-
posal and system operation costs, better production
process efficiency, and better quality.
246
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Technical understanding is essential f&r textile manag-
ers because cost and liability (civil and criminal) are their
responsibility. Pollution prevention concepts should be
part of every employee's training and! education pro-
grams. This applies especially to the staff who lay the
groundwork for pollution prevention, such as:
• Purchasing agents
• Process designers
• Fabric designers
• Product salespeople
Pollution prevention is an area that requires interaction
of workers, supervisors, engineers, chemists, manag-
ers, designers, suppliers, and customers. These human
resources are necessary to tackle tough pollution reduc-
tion problems identified in this document, such as:
• Salt
• Color
• Aquatic toxicity
• Air toxicity
• Hazardous waste
• Indoor air quality
6.7 Technical Understanding of
Processes
Understanding of processes is discussed from a person-
nel education and training point of view in Section 3.2,
"Enhanced Chemical and Pollution Prevention Exper-
tise." Everyone involved with textile manufacturing op-
erations needs an enhanced understanding of
processes on a global scale. A global view of operations,
encompassing the role of suppliers, designers, unit
processes, and customers is required to ensure maxi-
mum benefit from a pollution prevention program. This
is not part of pollution prevention project initiation but is
a long-term process that requires long-term commit-
ment.
Bide describes the need for better technical under-
standing at the worker and first-line supervisor level
(22). The same need exists in other parts of the textile
manufacturing process. Watkins describes an emerging
pollution prevention philosophy based on examining the
current and future challenges related to 'the textile indus-
try and targeting executives and managers, rather than
the typical unit process operators and supervisors (23).
The purpose of these efforts is to focus on a synergism
of pollution prevention/environmental protection and
sound business/profitability by globally integrating pollu-
tion prevention with product life cycle analysis (23).
A global view of operations, including suppliers, design-
ers, unit processes, and customers, is best accom-
plished by approaching the highest levels of manage-
ment. One purpose of this document is to provide man-
agers with a perspective that fosters a global approach
to pollution prevention, embracing designers, suppliers,
and customers. This is difficult in a fragmented and
competitive industry such as textiles.
6.8 References
1. Cascio, J. 1994. International standards for environmental man-
agement tools and systems. In: Proceedings of the GEMI Con-
ference on Environmental Management in a Global Economy,
March 16-17, Arlington, VA.
2. Samdini, G.M. 1995. ISO 140000: New passport to world mar-
kets. Chemical Engineering 102(6):41.
3. Crognale, G.G. 1995. Environmental management: What ISO
14000 brings to the table. TQEM 4(4):5.
4. Powers, M. 1995. Focus on the environment: Companies await
ISO 14000. Engineering News Record 234(21).
5. Gibson, D. 1995. Quality strategies in '95. Chemical Marketing
Reporter 247(15).
6. Oulette, J. 1995. Quality strategies '95: 9000's heir apparent.
Chemical Marketing Reporter 247(15).
7. van Berkel, R. 1995. A Dutch initiative for environmental improve-
ment of retail assortments. J. of Cleaner Production 3(1-2).
8. Wagner, S. 1993. Improvements in products and processing to
diminish environmental impact. COTTECH Conference, Raleigh,
NC (November 11-12).
9. Mohr, U. 1993. Ecology must be dealt with. Australasian Textiles
(January/February), p. 45.
10. Richardson, G.A. 1990. Are textiles finishing the environment: A
case study. Textile Institute Finishing Group Conference, Man-
chester, England (May 8).
11. Hollod, G.J., and R.R McCartney. 1988. Waste reduction in the
chemistry industry: DuPont's approach. E.I. du Pont de Nemours
and Co., Inc. (February).
12. Holme, 1.1992. Collaboration is the key to success. Textile World
(November), p. 33.
13. Hunt, G.E. 1989. Developing and implementing a waste reduc-
tion program. North Carolina Department of Environment, Health,
and Natural Resources, Pollution Prevention Program, Raleigh,
NC (May).
14. Richardson, S. 1991. Multimedia environmental concerns in warp
sizing: Low tech approaches to waste reduction. North Carolina
Pollution Prevention Program, Raleigh, NC (February).
15. Smith, B. 1986. Identification and reduction of pollution sources
in textile wet processing. North Carolina Department of Natural
Resources and Community Development, Pollution Prevention
Pays Program, Raleigh, NC.
16. Smith, B. 1994. Future pollution prevention opportunities and
needs in the textile industry. In: Pojasek, B., ed. Pollution preven-
tion needs and opportunities. Center for Hazardous Materials
Research (May).
17. Morris, H. 1991. Playing by the rules. Indus. Fabric Products
(September), p. 106.
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18. Smith, B. 1989. A workbook for pollution prevention by source
reduction in textile wet processing, Office of Waste Reduction,
North Carolina Department of Environment, Health, and Natural
Resources, Raleigh, NC.
19. Glover, B., and L. Hill. Waste minimization in the dye-house.
Textile Chem. and Colorist (June), p. 15.
20. Virlder Corporation. 1994. Fact sheet on environmental consid-
erations coding system. Charlotte, NC: Virkler Corporation.
21. Tomasino, C. 1994. Expert system for managing the environ-
mental impact of textile auxiliaries. In: Cotton, Inc., year-end re-
port, July-December, 1994. Raleigh, NC.
22. Bide, M. 1994. Letter to editor. Textile Chem. and Colorist (Au-
. gust).
23. Watkins, R.V. 1993. Introduction. In: Proceedings of the Confer-
ence for Executives and Managers on Environmental Issues Af-
fecting the Textile Industry—A National Perspective. Environ-
mental Policy and Studies Center, Hickory, NC, and North Caro-
lina Department of Health and Natural Resources, Raleigh, NC.
248
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Chapter 7
Selected Case Studies of Pollution Prevention in the Textile Industry
This chapter presents summaries of 21 published case
studies on successful implementation of pollution pre-
vention in textile processing. These cases are from ac-
tual production settings and reflect commercial use of
the concepts and methods presented iin Chapters 2, 3,
and 4. Hundreds of case studies have been published,
and undoubtedly, many thousands of applications re-
main unpublished. The case studies presented in this
chapter are typical, and many others are cited else-
where in this document.
(For information on the American Textile Manufacturers
Institute's program to promote pollution prevention
throughout the industry, see ATMI's 1994 report on its
E3 program in Appendix A.)
249
-------
Pollution Prevention Case Study: Adams-Millis, 1980
Location:
General target waste:
Specific target wastes:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
High Point, North Carolina, and Franklinton, North Carolina
Water
All water pollutants, energy
Segregation, direct reuse
Scheduling
Audit and analysis
Dyeing (batch)
Water conservation
Nylon pantyhose
This mill implemented dyebath reuse for the dyeing of nylon pantyhose in rotary
drum dyeing machines. Water.use decreased by 35 percent with a cost savings of
$0.02 per pound of production. The mill also reduced energy use by 57 percent.
Waste Reduction Resource Center for the Southeast. 1994. Textile case studies.
Waste Reduction Resource Center for the Southeast, Raleigh, NC.
250
-------
Pollution Prevention Case Study: Americal Corporation, 1993
Location:
General target waste:
Specific target wastes:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Henderson, North Carolina
Water
Biological oxygen demand (BOD), chemical oxygen demand (COD), fats, oil, and
grease (FOG), ammonia-nitrogen
Design-stage planning for processes
Chemical alternatives, substitution
Incoming raw material control
Raw material prescreening
Improved process control
Goal-setting, priorities
Audit and analysis
Substitution of physical (time/temperature) factors for chemicals
Raw materials—fibers
Raw materials—chemical specialties
Dyeing (batch)
Global (vendor involvement through chemical substitutions)
Nylon pantyhose
This company monitored incoming yarns for oil content. Alternative dyeing
auxiliaries and softeners were evaluated to find less-polluting alternatives. Dyeing
processes were optimized to the best temperature for maximum dye exhaust
without using excessive chemical dyeing assistants. The dye process was
extended for 15 additional minutes to obtain better exhaustion. Results showed
approximately a 60-percent drop in BOD and COD, a 20-percent drop in FOG, and
a 98-percent drop in ammonia-nitrogen. This resulted in a savings of $35,000
annually. Work continues with low-bath-ratio dyeing machines to further improve
pollution prevention.
North Carolina Office of Waste Reduction. 1993. Pollution prevention case studies.
North Carolina Office of Waste Reduction, Raleigh, NC.
251
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Pollution Prevention Case Study: Amital Spinning Corporation, 1992
Location:
General target wastes:
Specific target wastes:
Pollution prevention
techniques:
Unit processes:
Product:
New Bern, North Carolina
Water, solid
Packaging, process fiber waste
Design-stage planning for facility
Incoming raw material control
Marketing wastes
Process optimization
Optimized chemical handling
Segregation, direct reuse
Incentives
Goal-setting, priorities
Audit and analysis
Training, work practices
Raw materials—chemical specialties
Raw materials—chemical commodities
Raw materials—dyes
Dyeing (batch, yarn)
Global (vendor involvement through packaging swap)
Support area improvements
Purchasing specifications—packaging
Water conservation
Dyed high-bulk acrylic yarn
252
-------
Summary of activities:
Reference:
Amital combined process water reuse and solid waste control activities to reduce
waste and energy consumption. The company now purchases dyes and chemicals
in 400-gallon intermediate bulk containers (IBCs) or in bulk. Drum disposal
decreased by 69 per week, or about 3,500 annually. Pallet disposal decreased by
40 per week, or 2,000 annually. Pallet reuse and other packaging-oriented
activities involve raw material suppliers, so vendors were made a partner in the
reduction of packaging materials. Vendors must accept a return pallet for every
pallet delivered. For internal use, Amital fabricates custom pallets designed
specifically for ease of handling. Noncontact cooling water is recycled to the mix
kitchen. This reduces the need to heat water for mix kitchen use. Water use
decreased from 19.34 gallons per pound to 2.7, an 86-percent drop. Chemical use
was optimized, and process cycle times were reduced. Solid waste recycling
activities included cardboard, plastic, and acrylic yarn waste recycling. About 1.1
million pounds of solid waste were produced in 1992. Of that, about 933,000
pounds, or over 90 percent, was recovered/recycled. Total savings was estimated
at over $1.5 million annually for all activities combined. Amital received the
Governor's Award for Significant Pollution Prevention Achievement for these
activities.
Lynn, E. 1994. Open forum. Amer. Dyestuff Reporter. 83(10):9.
253
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Pollution Prevention Case Study: Bigelow Carpets, 1983
Location:
General target waste:
Specific target wastes:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Not disclosed
Water
All water pollutants, water conservation
Equipment modifications
Process alternatives
Segregation, direct reuse
Scheduling
Dyeing (batch, carpet)
Water conservation
Carpet
Dyebaths were reused by equipping pairs of dyeing machines with plumbing and
pumps capable of moving a processing bath back and forth from one machine to
the other. This allowed immediate reuse of dyebaths for over 20 cycles.
Scheduling of lots on the pair was coordinated to ensure efficient reuse. The cost
savings was $60,000 per year per pair of machines. Biological oxygen demand,
color, and other water pollutants were reduced significantly.
Berganthal, J. 1984. The case for direct dyebath reuse. Carpet and Rug Industry
(October). Cited in: Waste Reduction Resource Center for the Southeast. 1993.
Textile case studies. Waste Reduction Resource Center for the Southeast,
Raleigh, NC.
254
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Pollution Prevention Case Study: Binny Textiles, 1984
Location:
General target waste:
Specific target wastes:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Madras,-India
Water
Filter backwash water, washwater
Segregation, direct reuse -, ( •
Support area improvements
Water conservation
General textile operations
Suspended solids from filter backwashing usually are easy to settle. Filter
backwash was collected in a settling pond, held for 12 hours, then decanted for
nonprocess uses. The settled solids were periodically collected and landfilled. This
saved about 2 million gallons of water annually. In addition, internal reuse of
washwater in the preparation and dyeing departments reduced water use by over
100 million gallons annually. Also, about 2.5 million gallons were saved by reusing
water in the size department.
Waste Reduction Resource Center for the Southeast. 1993. Textile case studies.
Waste Reduction Resource Center for the Southeast, Raleigh, NC.
255
-------
Pollution Prevention Case Study: Century Textiles and Industries, 1990
Location:
General target wastes:
Specific target waste:
Pollution prevention
techniques:
Unit process:
Product:
Summary of activities:
Reference:
Bombay, India
Air, water, solid, hazardous
'Sulfide
Chemical alternatives, substitution
Process alternatives
Dyeing (continuous)
Dyed woven fabric
The company was applying sulfur dyes with the traditional sodium sulfide agents
and replaced them with an alkaline glucose solution. Initially, a substitution of 61
parts of 80-percent solids glucose solution for 100 parts of 50-percent sodium
sulfide was used. Handling difficulties were encountered because of the high
viscosity and messy nature of 80-percent glucose solution. Further work with 65
parts of a 50-percent reducing sugar (e.g., corn sugar) waste stream from another
industry was successful. Production and fastness properties of the dyed materials
were not affected.
Sharma, A.M. (no date). Unpublished study cited in: Waste Reduction Resource
Center for the Southeast. 1993. Textile case studies. Waste Reduction Resource
Center for the Southeast, Raleigh, NC.
256
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Pollution Prevention Case Study: American Enka Company, 1985
Location:
General target wastes:
Specific target wastes:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Enka, North Carolina
Air, water
Solvent emissions
Segregation, recycle, direct reuse
Raw materials—fiber manufacture
Yarn formation
Support area improvements
Nylon yarn, polymer films
American Enka uses isopropyl alcohol (IPA) in the production of polymeric film
products. Attempts to use outside recovery of the IPA were not successful because
of high losses (15 percent) and contamination from other materials (e.g., benzene,
alkyl benzenes, chlorinated hydrocarbons, Dowtherm) that were being recovered in
the same distillation operation. This is now being recycled/recovered in-house. The
solvent is segregated from other wastes and distilled for production. The recovery
rate is 90 percent, and the quality of recovered materials is sufficient for the
production use. In addition, the still bottoms are used as an asphalt emulsifier in
another product line. The annual cost savings is $90,000. The payback period for
the purchase of the $7,500 distillation unit was 1 month. Air and water emissions
decreased. Costs and liabilities of transporting IPA raw material and IPA waste
were avoided.
Huisingh, D. 1985. Profits of pollution prevention. North Carolina Office of Waste
Reduction, Raleigh, NC.
257
-------
Pollution Prevention Case Study: Nordic Water Care Project, 1976 to 1981
Locations:
General target waste:
Specific target waste:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Denmark, Finland, Norway, Sweden
Water
Water conservation
Design-stage planning for processes
Design-stage planning for facility
Equipment selection
Process alternatives
Segregation, direct reuse
All wet processes
Preparation
Dyeing
Printing
Finishing
Water conservation
Dyed and finished textile fabrics
Between 1976 and 1981,15 textile operations minimized water use in the Nordic
Water Care Project. Some of the more productive and notable activities to reduce
water use were as follows: drop/fill replaces overflow washing in jigs, beams,
becks, and jets; automatic water flow shutoffs on continuous ranges saved about
25 percent; countercurrent washing. Horizontal washers were shown in this study
to be twice as efficient as vertical washers (i.e., one horizontal .washer was as
efficient as two vertical washers, all having the same water consumption).
Asnes, H. 1978. Reduction of water consumption in the textile industry. IFATCC
Conference. Cited in: Waste Reduction Resource Center for the Southeast. 1993.
Textile case studies. Waste Reduction Resource Center for the Southeast,
Raleigh, NC.
258
-------
Pollution Prevention Case Study: Hampshire Hosiery, Ellen Knitting Mills, 1985
Location:
General target wastes:
Specific target waste:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Spruce Pine, North Carolina
Water, energy
Wastewater temperature
Design-stage planning for processes
Design-stage planning for facility
Marketing wastes
Incentives
Dyeing (batch, yarn)
Global (acquisition and use of wastes from other nearby industries)
Support area improvements (boiler, wastewater handling)
Hosiery
High-temperature discharges from Hampshire Hosiery dyeing operations were
damaging the city sewer system. Segregation of the hot water from dyeing and
installation of a heat recovery unit for a cost of $100,000 allowed incoming water
to be heated to 105°F from the ambient 80°F. Saved were 52,000 gallons of fuel oil
per year, In another activity, the mill installed a hopper, storage silo, conveyer belt,
and other handling equipment to burn sawdust from nearby furniture operations.
This eliminated the need for 300,000 gallons per year of fuel oil. The sawdust is
obtained at a cost of $20 per ton. Overall fuel savings is 66 percent. The boiler
conversion to burn sawdust cost $800,000 and the annual savings was $225,000
for reduced fuel costs. Air quality impact was not documented, but the study
reported that air pollution decreased.
Huisingh, D. 1985. Profits of pollution prevention. North Carolina Office of Waste
Reduction, Raleigh, NC.
259
-------
Pollution Prevention Case Study: Harriet & Henderson Yarns, Inc., 1993
Location:
General target waste:
Specific target waste:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Henderson, North Carolina; Clarkton, North Carolina; Summerville, Georgia
Solid
Cotton cleaning waste
Process optimization
Marketing of wastes
Recovery for reuse
Incentives
Goal-setting
Yarn formation
Global (marketing of wastes)
Spun cotton and cotton blend yarns
Harriet & Henderson Yarns was landfilling about 44,000 pounds of cotton cleaning
waste per week at a cost of $800 per week. A goal was set to find uses for the by-
product, which comprised cellulosic plant parts other than fiber as well as some
cotton cellulose hairs. Processes were optimized so that less cellulose fiber was
lost during processing (i.e., some of the previously discarded short fibers were
recovered as fairly pure cotton lint for resale). This reduced the amount of waste
by 16,000 pounds per week and provided a payback because of better raw
material use. The sale of the recovered lint brought about $250 per week income
and saved about $300 in landfill costs. The nonrecovered cotton trash, stems, and
leaves were investigated as animal feed and soil amendment for nutrient value
and erosion control. The by-product must be analyzed to ensure suitability for
feedstock and to determine nutrient value. Animal feed use pays about $200 per
week for 13,600 pounds of this material. The company now has a waiting list of
farmers wanting to buy the material.
North Carolina Office of Waste Reduction. 1993. Pollution prevention case studies.
North Carolina Office of Waste Reduction, Raleigh, NC.
260
-------
Pollution Prevention Case Study: JP Stevens & Company, Inc., 1987
Location:
General target wastes:
Specific target wastes:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Lincolnton, North Carolina
Water, hazardous, indoor workplace air
Aquatic toxicity, odors
Design-stage planning for facility
Equipment selection
Substitution of physical agent for chemical agent
Process alternatives
Improved monitoring and control
Goal-setting, priorities
Audit and analysis
Yarn formation (carding, roving, spinning, winding)
Support area improvements (air washers)
Water conservation
Yarn
Ultraviolet (UV) light was substituted for chemical biocides in air washers and
cooling towers in a textile mill. During a 6-month test period, extensive data were
collected. Results showed improved worker safety, reduced discharge of biocides
to the sanitary sewer, reduced chemical inventory and handling, workplace air
quality improvements, reduced foaming and pH problems in wastewater, better air
washer performance, and more consistent control of workplace air quality. UV
disinfection reduced microbial populations in the air washing/cooling units to an
averaage of 104 colony forming units per milliliter (CFU/mL) over a 6-month test
period. The UV system operated with no required maintenance or repairs during
the test. An alternative method using reduced UV light plus hydrogen peroxide
produced similar results but was more expensive. A supplemental study (to be
released later) is evaluating the addition of filters to the system. For the test
system, capital costs were $4,560. Startup costs were $1,500. Based on chemical
savings, the payback is 11 to 18 months. Extensive test protocol information, data,
full analysis, and engineering details are presented in a 30-page report.
Smith, J.E., and R.B. Whisnant. 1988. Evaluation of a Teflon-based ultraviolet light
system on the disinfection of water in a textile air washer. North Carolina Office of
Waste Reduction, Raleigh, NC.
261
-------
Pollution Prevention Case Study: Neuville Industries, Inc., 1993
Location:
General target waste:
Specific target wastes:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Hildebrand, North Carolina
Solid
Paper, cardboard, polybags
Incoming raw material control (packing)
Segregation, recycle/reuse
Incentives
Goal-setting, priorities
Audit and analysis
Training, attitudes, work practices
Fabric formation—knitting
Preparation
Dyeing (batch)
Finishing
Global (vendor involvement through packaging)
Purchasing specifications—packaging
Hosiery products
A recycling committee was established to reduce the solid waste disposal burden.
Employee suggestions were an integral part of program initiation. Cardboard,
cones, paper, scrap metal, packing materials, knitting oils, polybags, and pallets
were targets. Program savings are returned as employee benefits. Waste
decreased by about one-third from 266 to 180 cubic yards per week over a 2-year
period, or about 4,300 cubic yards annually. The savings was $15,127 per year.
North Carolina Office of Waste Reduction. 1993. Pollution prevention case studies.
North Carolina Office of Waste Reduction, Raleigh, NC.
262
-------
Pollution Prevention Case Study: Riddle Fabrics, 1993
Location:
General target waste:
Specific target waste:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Kings Mountain, North Carolina
Water
Biological oxygen demand (BOD)
Chemical alternatives, substitution
Process modification
Segregation, direct reuse
Housekeeping
Audit and analysis
Water conservation
Preparation
Water conservation
Cotton label tape
Holding tanks were installed for bleach baths, allowing reuse. The bath was
reconstituted to correct strength after analysis by titration. BOD decreased over 50
percent from 842 milligrams per liter to 400 milligrams per liter. Water use also
decreased. The mill came into compliance with permits and realized economic
benefits.
North Carolina Office of Waste Reduction. 1993. Pollution prevention case studies.
North Carolina Office of Waste Reduction, Raleigh, NC.
263
-------
Pollution Prevention Case Study: Russell Mills, 1989
Location:
General target wastes:
Specific target wastes:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Undisclosed
Water, energy
Heat recovery/reuse
Design-stage planning for processes
Design-stage planning for facility
Equipment maintenance
Segregation, direct reuse
Improved process control
Preparation
Dyeing
Finishing
Support area improvements
Water conservation
Dyed and finished textile fabrics
The mill installed boiler blowdown and steam condensate recycling. The resulting
savings in boiler fuel alone was $1,000 per day.
Smith, B. 1989. Amer. Dyestuff Reporter. 78(5).
264
-------
Pollution Prevention Case Study: Thiele Engdahl, 1988
Location:
General target wastes:
Specific target wastes:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Winston-Salem, North Carolina
Water, air, hazardous
Solvents, isopropyl acetate (IPAc)
Optimized chemical handling
Segregation, recovery, direct reuse
Nonprocess chemical control
Printing
Support area improvements
Printed fabric
Printing equipment was cleaned with solvents, including IPAc. Solvents were
reused twice before onsite redistillation for recovery and reuse. Payback for the
distillation system was 2 years. The discharge of solvents to water and air
decreased.
North Carolina Office of Waste Reduction. 1993. Pollution prevention case studies.
North Carolina Office of Waste Reduction, Raleigh, NC.
265
-------
Pollution Prevention Case Study: Ti-Caro, 1993
Location:
General target waste:
Specific target waste:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Newton, North Carolina
Water
Biological oxygen demand (BOD)
Chemical alternatives, substitution
Design-stage evaluation—products
Process alternatives
Raw material prescreening
Process optimization
Audit and analysis
Raw materials—chemical specialties
Fabric formation
Preparation
Dyeing (batch)
Finishing
Global (vendor involvement through prescreening)
Purchasing specifications
Water conservation
Knitted fabric (dyed and finished)
Ti-Caro required all suppliers to provide environmental impact statements on
chemical specialties (e.g., knitting oils, softeners, emulsions, dyes) before
production use. Bleaching was done by a pad-batch process, which uses much
less water and energy. The bath ratio decreased on all batch processes to 10:1. All
processing baths were neutralized (acid/base or redox) before discarding. In some
cases, machines were double loaded by piggybacking two lots on the same dyeing
machine. Also, scouring and dyeing steps sometimes were combined. Each shade
was individually evaluated to determine if it required prebleaching. Water
consumption was well below 10 gallons per pound, which is less than half the
amount used by other knit dyers. For this reason, the City of Newton granted a
modification in BOD permit limits, rewarding the water conservation efforts of the
mill.
North Carolina Office of Waste Reduction. 1993. Pollution prevention case studies.
North Carolina Office of Waste Reduction, Raleigh, NC.
266
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Pollution Prevention Case Study:
Ciba-Geigy Corporation, Toms River Plant, 1990
Location:
General target waste:
Specific target wastes:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Toms River, New Jersey
Water
Color, total organic carbon (TOC), laboratory wastewater, landfill leachate, process
water
Design-slage planning for processes
Design-stage planning for facility
Equipment selection
Equipment maintenance
Process alternatives
Optimized chemical handling
Scheduling
Segregation, direct reuse
Improved process control
Goal-settFng, priorities
Audit and analysis
Training, work practices
Raw materials—dyes
Support airea improvements
Water conservation
Dyestuff and chemical standardization
A goal was set to reduce water from approximately 500,000 gallons per day to less
than 10,000 gallons per day. Target wastewater streams were cooling water, steam
quenching, process water, equipment cleaning, air washer condensate, and
stbrmwater. The goal was achieved by an 18-step procedure over a 5-year period.
Activities included recycling point sources, implementing "dry" cleaning methods,
scheduling improvements, team building, and facility modification. Ultrafiltration
and reverse osmosis were used as part of the study. The capital expenditure was
$6 million for chillers, high-pressure cleaning equipment, plumbing and storage,
Ultrafiltration and reverse osmosis systems, and dust collectors. Engineering
diagrams are provided in the study. Process optimization and design
improvements were evaluated, especially nonproduction cleaning processes.
Extensive data are presented.
Kleinbauer, R. (no date). Standardization without effluent at Toms River. Ciba-
Geigy Corporation, Toms River, NJ.
267
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Pollution Prevention Case Study: Unidentified Company, 1985
Location:
General target waste:
Specific target waste:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
International
Water
Water conservation
Design-stage planning for processes
Design-stage planning for facility
Process alternatives
Segregation, direct reuse
Goal-setting, priorities
All wet processing operations
Preparation
Dyeing
Printing
Finishing
Support area improvements
Water conservation
Dyed and finished textile fabrics
Water consumption was reduced by several measures over a 1-month period.
Flow on wash boxes was optimized. Countercurrent flow was installed on all
soapers, mercerizing range, J-boxes, etc. Washwater was reused in upstream
process for less crucial uses (e.g., print blanket washing). All boiler condensate
was reused as boiler feed water. Steam condensate from caustic recovery
evaporator was reused in mercerizer washer. Overflow/running washes on dye jigs
were replaced with static washes. Alternate oxidizer systems, which were easier to
wash off, were evaluated for use on continuous vat dyeing ranges. Similar
modifications were made in other processes. Water consumption in the mill
decreased by 40 percent.
North Carolina Office of Waste Reduction. 1993. Pollution prevention case studies.
North Carolina Office of Waste Reduction, Raleigh, NC.
268
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Pollution Prevention Case Study: Unidentified Company, 1982
Location:
General target waste:
Specific target waste:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Undisclosed
Water
Size—polyvinyl alcohol (PVA)
Design-stage planning for products
Design-stage planning for processes
Chemical alternatives, substitution
Process alternatives
Segregation, direct reuse
Yarn formation
Slashing and sizing
Fabric formation
Preparation
Global (combined effort in several unit processes)
Testing, analysis, monitoring
Woven textile fabrics
A closed-loop ultrafiltration and recycling system was installed to recover PVA. The
PVA was substituted for previously used starch and other nonrecoverable sizes.
The project performance was closely monitored for 16 months for pollution and
textile quality performance. The capital investment was $600,000, and the
operating costs were $61,000 annually. Annual savings were reported to be
$420,000 for the value of recovered size, $100,000 for savings in enzymes, and
$20,000 for steam savings, or a total of $540,000 annually.
North Carolina Office of Waste Reduction. 1993. Pollution prevention case studies.
North Carolina Office of Waste Reduction, Raleigh, NC.
269
-------
Pollution Prevention Case Study: United Piece Dye Works, 1989
Location:
General target waste:
Specific target wastes:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Edenton, North Carolina
Water
Phosphates
Design-stage planning for processes
Design-stage planning for product
Enhanced expertise
Chemical alternatives, substitution
Process alternatives
Raw material prescreening
Improving information
Goal-setting, priorities
Audit and analysis
Raw materials—chemical specialties
Raw materials—chemical commodities
Dyeing (batch)
Finishing
Global (vendor involvement through prescreening)
Purchasing specifications—phosphates
Dyed fabric
Sources of phosphate were identified by reviewing vendor information, especially
the material safety data sheet (MSDS). Processes, products, and process
chemistry were reviewed. Many substitutions of nonphosphate materials for
phosphate-containing materials were made. The result was a decrease in
phosphate in the effluent from 7.7 milligrams per liter to 1.0 milligram per liter.
Schecter, R., and G. Hunt. 1989. Case summaries of waste reduction by industries
in the Southeast. Waste Reduction Resource Center for the Southeast, Raleigh,
NC.
270
-------
Pollution Prevention Case Study: West Point Pepperell, 1985
Location:
General target wastes:
Specific target wastes:
Pollution prevention
techniques:
Unit processes:
Product:
Summary of activities:
Reference:
Lumberton, North Carolina
Hazardous and all others '•••-•
Hazardous metals and all others
Chemical alternatives, substitution .
Incoming raw material control ,
Raw material prescreening
Improving information
Audit and analysis
Raw materials—chemical specialties
Raw matterials—chemical commodities
Raw materials—dyes
Fabric formation
Dyeing (batch)
Finishing ,
Global (vendor involvement through prescreening information)
Purchasing specifications
Dyed knit cotton and cotton blend fabric
A committee prescreened raw material (dyes and chemicals) to ensure that
offensive, toxic, and other objectionable material use were minimized in the
production facility. In the event that raw materials with undesirable properties had
to be used (i.e., no alternatives exist), difficult raw materials were identified to all
workers before use. This process entailed no capital costs. Benefits, such as the
ability to dispose of waste treatment sludges (because they do not contain
objectional metals or toxics), were realized.
Huisingh, D. 1985. Profits of pollution prevention. North Carolina Office of Waste
Reduction, Raleigh, NC.
271
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Appendix A
ATMI's E3 Program: Encouraging Environmental
Excellence Report 1995
273
-------
-------
"It's one thing
for a company to
say it believes in
protecting the
environment,
it's another matter
to take action and do
something about it.
And that's what
ATMI.'s E3 program
is" all about —
taking action."
— Gerald B. Andrews,
E.3 chairperson and
president and CEO.
Johnston Industries, Inc.
ENCOURAGING ENVIRONMENTAL EXCELLENCE
REPORT 1995
Encouraging .Environmental Excellence, also known as E3, was created by the American
Textile Manufacturers Institute (ATMI) to advance the U.S. textile industry's already strong
environmental record. Launched in 1992, E3 is a voluntary initiative that provides ATMI
member companies with a forum to share ideas and strategies for dealing with environmental
concerns. More important, the program challenges textile companies to further strengthen
their coiporate commitment to the environment.
And that commitment to preserving the environment is exceptional. Each year, U.S. textile
companies invest millions of dollars to try to make sure that their processes for manufacturing
textiles iare environmentally friendly. In 1993, the most recent year for which data is available,
the industry spent approximately $313 million on pollution controls and related equipment.
"It's one thing for a company to say it believes in protecting the environment, it's another
matter to take action and do something about it," notes Gerald B. Andrews, E3 chairperson
and president and CEO of Johnston Industries, Inc. "And that's what ATMI's E3 program
is all about — taking action. At Johnston Industries, we take the E3 program very seriously,
involving everyone from the CEO to individual employees. The program has helped em-
ployees understand why environmental preservation is so important to our facilities and to
our communities. For us, participating in the E3 program is good business. We wouldn't
have it any other way."
How THE E3 PROGRAM WORKS
I o qualify for E3 membership and annual recertification, an ATMI member company must be
in compliance with all federal, state and local environmental laws, something they must do
anyway. The E3 program, however, encourages companies to get out in front of regulations
and set standards for other industries to follow.
Besides being in compliance with the law, a company must adopt a 10-point plan. The plan's
guidelines requke that a company develop a corporate environmental policy and set annual
goals for reducing waste and conserving water and energy. In addition, a company must
develop an outreach program with suppliers and customers to encourage pollution prevention
and waste minimization, develop employee education and community awareness programs and
audit its facilities.
275
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At the end of each year, a company must submit a detailed report describing its progress in
achieving its environmental goals and how those goals were achieved. A company also must
develop new goals for the coming year.
Once a company qualifies for E3, membership renewal is not automatic. If an E3 member
company violates an environmental statute, it is required to provide ATMI with a written
explanation of the violation along with its plan for corrective action. ATMI reserves the right
to remove a company from the E3 program if it fails to comply with an environmental statute or
theprogram's guidelines. In 1995,52 companies were members of the E3 program.
For companies that qualify for membership, ATMI offers its assistance by providing manuals
on how to conduct environmental audits. ATMI also supplies case studies and hosts annual
education seminars.
To advertise their commitment to environmental excellence, member companies can use the
E3 logo and hang tag on their products. They may also contract with their customers to use
the hang tag on their products, provided customers specify the cloth, yam or thread was
produced by an American textile manufacturer that promotes environmental preservation.
E3 PROGRAM GUIDELINES
The program's 10 guidelines provide the framework for a company's application to
and retention in the program. Each company must meet the following guidelines:
I. Formulate and submitto ATMI a company environmental policy.
2. Describe in detail senior management's commitment toward environmental
excellence and how greater environmental awareness is encouraged throughout
the company.
3. Submit a copy of its environmental audit form describing how it ensures that
officers and employees are in full compliance with existing laws.
4. Describe how it has worked with suppliers as well as customers to address
environmental concerns.
5. List its environmental goals and targeted achievement dates.
6. Describe its employee education program.
7. Identify and describe its emergency response plans.
8. Describe how it has relayed its environmental interests and concerns to. the
surrounding community, residents and policymakers,
9. Describe how it has been able to offer environmental assistance and insights
to citizens, interest groups, other companies and local government agencies.
10. Describe its interaction with federal, state and local policymakers.
276
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WHO OVERSEES THE E3 PROGRAM?
The E3 program is managed by a general chairperson, an industry task force and an indepen-
dent advisory board. The eight-person task force is made up of environmental engineers and
public relations professionals from the industry. The group is responsible for managing the
program's day-to-day operations, carrying out policy recommendations made by the advisory
board and organizing educational seminars and workshops.
The advisory board is made up of nine representatives from state environmental enforcement
agencies, businesses, environmental organizations and academia. The board is responsible for
reviewing the criteria for the E3 program and the environmental records of member companies.
Board members also are required to tour several textile facilities each year.
The success of the E3 program is due in large part to the fact that it is a voluntary initiative.
What distinguishes an E3 member company is its willingness to work with government
regulators, community groups and employees to address environmental issues quickly and
responsibly. In fact, the industry has been recognized as a leader in environmental preserva-
tion by the Environmental Protection Agency (EPA).
EPA's WasteWi$e program is a voluntary initiative designed to encourage companies to
reduce waste, which is defined as anything that is sent to a landfill. According to Lynda
Wynn, manager of the Waste\Vi$e program!, "ATMI and its members in the Encouraging
Environmental Excellence program are doing an outstanding job of reducing waste and
improving the environment ATMI is one of the most proactive trade associations on pollu-
tion prevention issues, working with its members to demonstrate that conserving natural
resources is good for business and for our environment."
The U.S. textile industry has also been recognized as a leader in environmental preservation by
a number of state and local governments as well as by many local communities.
1995 ENVIRONMENTAL HIGHLIGHTS
RECYCLING AND WASTE MINIMIZATION
Evidence of E3 member companies' commitment to the environment was especially strong in
the recycling area. Companies recycled everything from office paper to dyes and fiber. Some
textile companies helped other textile firms recycle their waste. Others recycled products — for
example, soda bottles — to make new products, such as denim. Through efforts like these and
others, the amount of waste sent to landfills was reduced dramatically.
"ATMI is one of
the most proactive
trade associations on
pollution prevention
issues, working with
its members to
demonstrate that
conserving natural
resources is good
for business and for
our environment."
— Lynda Wynn,
manager of EPA's
WasteWi$e program
277
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When a 100-year-old textile mill and warehouse were demolished, Dan River Inc. recycled and
resold roughly 4.7 million pounds of materials, including 2 million pounds of bricks and 1.2
million pounds of decking boards made from heart of pine, a wood that is all but extinct today.
Wellington Sears Company, a division of Johnston Industries, Inc., is involved in a project to
compost waste fiber generated by the company's Utilization Plant, which itself is a textile
recycling facility. The plant takes waste fiber and scraps from other textile and apparel
manufacturing facilities and converts them into useable forms, which go into making products
such as mops and mattress pads. In the process of recycling, however, additional waste is
generated. So the company conducted a study to determine the feasibility of composting the
waste material. The study concluded that the waste would make an excellent compost and,
as a result, Wellington Sears began operating a full-scale compost facility on site. The com-
pany estimates it is keeping more than 5,000 tons of waste out of the landfill each year.
Swift Textiles, Inc. is using recycled soda bottles to make denim. The fabric contains 80 percent
cotton and 20 percent polyethylene terephthalate, which comes from recycled soda bottles.
The empty soda bottles are sorted by color, washed, dried and melted into pellets. The pellets
are then remelted, spun into fiber and combined with cotton yam, dyed and woven to produce
the denim.
Sunbury Textile Mills, Inc; recycles 90 percent or
more of its office paper, aluminum cans, drums,
cones, spools, cardboard and yarn waste. Through
design changes in its yam manufacturing operation,
the company reduced yarn waste in 1995 by 45 tons.
The company reduced the overall amount of waste it
sent to the local landfill in 1995 by 402 tons. (See
chart at left.)
The Kent Manufacturing Company, which is in
the business of manufacturing wool yarn, does not
generate much landfill-bound waste. Even so, the
Pickens, S.C., company enlisted the help of the
county recycling department in setting up a recycling program. The company has placed a
number of recycling containers throughout the organization. Each department has containers
for paper, aluminum cans, plastic, fibers, cones and tubes. Before the recycling program began,
Kent Manufacturing was sending an average of four dumpsters of waste a week to the county
landfill. With the new program in place, the company averages just one dumpster of waste
per week.
Sunbury Textile Mills, inc.
Totals of Materials Recycled
500
1400
1300
|zoo
QL
2100
1992 1993 1994 1995
Cardboard, Papar, Yarn Waata. Conai, Plattte, Melala
278
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Southern Mills, Inc.'s biggest challenge was to reduce solid waste sent to local landfills. The
company tackled the problem by challenging each manufacturing plant to organize a committee
to work with its corporate waste reduction committee to identify what was being transported to
the landfills. The result: the company discovered it was sending a lot of drums to the landfill.
By working with its suppliers, Southern Mills now only uses drums that can be returned to the
original vendor. The company estimates that in 1995 it saved 42,000 pounds of metal and fiber
drums from being sent to the landfill.
Carolina Mills, Inc. also works with its vendors as well as its customers to reach the point where
every item that comes on company grounds will be recycled. In 1995, the company reduced the
amount of waste it sent to the landfill by 65 percent. Meanwhile, Fruit of the Loom reduced the
amount of waste it sent to the landfill in 1995 by 2 million pounds a month.
When Fieldcrest Cannon, Inc. treats the wastewater that results from manufacturing sheets and
towels, additional waste, known as biological solids, is generated. Rather than disposing of
the waste at a landfill or burning it, the company gives it to local farmers, who use it as fertilizer.
The waste makes an ideal fertilizer because of its high content of phosphorus and nitrogen.
Alice Manufacturing Co., Inc. no longer sends paper to the landfill since it implemented a
recycling program. The company estimates that in 1995 it recycled 476,000 pounds of paper,
256,000 pounds of cardboard and 77,000 pounds of plastic bale wrap.
Unifi, Inc., with the help of Sonoco, expanded a company recycling facility, where fiber, paper,
tube waste and corrugated cardboard are baled using highly automated equipment. The
company recycles 95 percent or more of its aluminum cans, drums, cones, spools, packaging,
plastic dye springs, cardboard, waste oil, wooden pallets and fibers.
Spartan Mills is working with its county recycling department to examine the possibility of
recycling dust from fiber reclamation. The company also recycles 90 percent or more of its office
paper, aluminum cans, drums, cones, spools, packaging, cardboard, wooden pallets and fibers.
A number of companies are proud of their 100 percent recycling record. Stonecutter Mills
Corporation recycles 100 percent of its drums, plastic, packaging, cardboard, fluorescent bulbs,
glass and waste oil. Wehadkee Yarn Mills is recycling 100 percent of its dyes, aluminum cans,
drums, plastic, cones, spools, packaging, cardboard, wooden pallets and fibers.
American & Efird, Inc. has instituted a recycling program specifically for plastic. American &
Efird customers can ship the company's plastic cones, spools and polybags to one of American
& Efird's 11 recycling centers located around the country. These products are then consoli-
dated and shipped to a reprocessing center.
279
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Russell Corporation received an award from the Alabama Recycling Coalition for having the
top in-house recycling program in the state. The company recycles on site 95 percent or more
of its office paper, aluminum cans, drums, plastic, cones, spools, cardboard, wooden pallets,
fibers and apparel waste from its cutting and sewing operations. And Artec Industries, Inc.
reports that it recycles 95 percent or more of its office paper, aluminum cans, drums, plastic,
cones, spools, packaging, cardboard, wooden pallets and fibers.
POLLUTION PREVENTION AND
WATER AND ENERGY CONSERVATION
Pollution prevention as well as water and energy conservation were high priorities for many
E3 member companies. By recycling wastewater, a number of companies saved thousands of
gallons of water a week. Other actions companies took to protect the environment ranged from
using chemicals and dyes that are more environmentally friendly to buying equipment that is
more energy efficient.
The biggest challenge Mount Vernon Mills, Inc. faced was to help improve the operation of a
30-year-old local wastewater treatment facility. Because Mount Vernon Mills supplies almost
all of the wastewater to the facility, the company funded the vast majority of an $11 million
project to upgrade the facility. The company is trying to improve the quality of wastewater it
sends to the treatment facility by using the most environmentally friendly dyes and chemicals
and by working with its vendors to see whether some of those dyes can be recycled. In
addition, by recycling packaging materials collected from its customers and reusing solid
waste that is generated internally, Mount Vernon Mills has reduced the amount of waste it has
sent to the landfill during the last two years by 32 percent.
When Dixie Yarns, Inc. purchased a company in North Carolina, it inherited the environmental
contamination a previous owner had left behind. Rather than waiting for the EPA to man-
date action, Dixie Yams voluntarily took steps to clean up the site. The company removed
2.3 million pounds of contaminated soil at a cost of $60,000. Dixie Yams currently is awaiting
the appropriate permits from the state so it can begin cleaning up the water, which is also
contaminated.
By recycling wastewater, Mayfair Mills, Inc. estimates it saved between 4,000 and 5,000 gallons
of wateraweekin 1995.
At Harriet & Henderson Yarns, every facility has a water tower on site, which helped the
company reduce purchased water and wastewater flow by 20 percent. By reusing the water,
the company also has reduced the amount of energy and chemicals it uses.
280
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Cone Mills Corporation, which is headquartered in North Carolina, installed a color removal
system to remove dye from its wastewater before the water is discharged into a local river. The
state is encouraging other area companies to take similar action.
To conserve'energy, Shuford Mills, Inc. installed a new dryer at its package dyeing facility. As
part of the project, the company also renovated a 20,000-gallon storage tank so that hot water
can be recovered during the drying process and reused in the dyeing operation.
E3 Member Companies' Waste Reduction Record
1992V. 1995
60%-
50%-
0%
1992
At Armtex, Incorporated, each plant has formed an
energy conservation team. The team is responsible
for conducting plant audits and making recommenda-
tions for conserving energy.
Borden Manufacturing Company, in cooperation
with the state power and light company, installed a
computer system that notifies Borden whenever the
utility company's power usage is at peak capacity.
When peak capacity is reached, the computer system
sounds an alarm and Borden shuts down selected
equipment for a specified duration. By voluntarily
reducing power consumption during peak periods,
Borden has received credits on its monthly power bills. In 1995, those credits translated into a
savings of several thousand dollars.
At Coats American, all utilities and production equipment are inspected regularly to spot
problems and repair leaks quickly. Production is evaluated periodically against Standard
usage amounts to spot waste other than leaks. As a result of these inspections, the company
estimates that in 1995 it saved approximately $300,000 to $500,000 on its energy bill alone.
Converting to a more energy-efficient lighting system saved Pendleton Woolen Mills 4 million
kilowatt-hours in 1995, which translated into a savings of $166 million.
Burlington Industries, Inc. continued its 15-year plan to replace all of its refrigeration machines
with ones that contain a more environmentally friendly refrigerant. In 1995, the company
replaced 13 machines.
Belding Heminway Co., Inc. improved air quality by eliminating the use of a common ozone-
depleting chemical from its manufacturing operations.
Through chemical substitutions, Collins & Aikman Products Co. has reduced SARA 313
releases by 95 percent since 1988. (SARA is the Superfund Amendments and Reauthorization
199S
281
-------
Act.) The 1986 amendments require companies to report which toxic chemicals they release
into the air. The goal is to get industries to reduce the number of chemicals they emit
By making some modifications at one of its textile finishing operations, WestPoint Stevens Inc.
reduced air emissions by nearly 89 percent. As a result, the plant no longer has to apply for a
permit under Title V of the Clean Air Act, the federal law that governs air emissions. Not only
has the environment benefited, but WestPoint Stevens estimates that being removed from
Title V will save $50,000 a year in compliance, record-keeping and personnel costs, and the
plant also will be able to avoid the expensive process of applying for a Title V permit.
Because it reduced its air emissions, the New Cherokee Corporation is no longer required to
file a permit with the state of Tennessee under the Clean Air Act. The company reduced
emissions by eliminating the use of oil as a fuel and by designing a more efficient way to
deliver dye to the production process.
ENVIRONMENTAL MANAGEMENT,
AND AUDITING SYSTEMS
I he E3 program requires a strong commitment from senior management to protect the
environment, and member companies' environmental management and auditing systems are
evidence of that commitment. Environmental management and auditing, however, cannot end
there. Employee involvement through education and training is also critical to the success of
any company's environmental program.
The environmental manager for Johnston Industries, Inc. reports directly to the corporate vice
president of operations. The environmental manager, who is a licensed engineer, is respon-
sible for all aspects of environmental compliance, including air and wastewater permits,
pollution prevention, recycling and hazardous and solid waste disposal. Each year, all facilities
at Johnston Industries undergo a comprehensive environmental compliance audit. If neces-
sary, corrective actions are scheduled and tracked until they are resolved.
Sara Lee Knit Products, a division of the Sara Lee Corporation, has an environmental aware-
ness program in place at all of its facilities. The company tries to raise awareness about the
importance of protecting the environment by periodically running articles in the company
newsletter and by participating in events, such as Earth Day. The company's corporate office
sponsors annual-educational seminars for facility managers and environmental coordinators.
Bloomsburg Mills Inc. trained all employees on how to identify, store, handle and dispose of
hazardous materials. Each plant has integrated the environmental program into its monthly
safety inspections, with special emphasis on how to handle containers that are not labeled.
282
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Although relatively few chemicals go into lihe manufacturing of woven fabrics, Arkwright Mills
continually audits its facilities, looking for any potential chemical spills as well as possible
water contamination. A report is given to ithe board of directors at each quarterly meeting.
Plant managers at Hamrick Mills are in constant communication with the company president
about environmental issues. The company conducts voluntary walk-through inspections
every month. To add credibility to the program, the company also hires independent auditors
to inspect its facilities every other year.
The environmental program at Inman Mills is headed by a company vice president. The
company holds monthly meetings for senior managers and plant personnel on safety and
environmental issues.
At Dominion Yam Corporation, plants are required to immediately notify the corporate office
about spills or other environmental problems. A report is sent to the director of environmental
safety and health at the Dominion Yarn's parent company, Dominion Textiles, Inc. The parent
company, in turn, reports this information to the board of directors.
COMMUNITY INVOLVEMENT
With policymakers and the public focusing increasingly on environmental issues, the
relationship between textile companies and the communities in which they operate is more
important than ever. One of the tenants of the E3 program is for each company to offer its
assistance and expertise on environmental issues to others in the community, including
citizens, civic organizations and schools. In turn, communities across the country have
recognized the many contributions E3 member companies have made to their neighborhoods,
cities and states.
Employees at Avondale Mills, Inc. teamed up with
representatives from the state power company and
various government and regulatory agencies to clean
up a local stream so people could swim in it In
addition, a threatened species of water lily continues
to thrive in sections of the stream.
Opp and Micolas Mills, a division of Johnston
Industries, Inc., sponsored a poster and coloring
contest for local schools, including preschools, to
teach young children about the importance of
preserving the environment.
E3 Member Companies' Waste Reduction
Industry v. E3 Companies
50 -
40 -
f 20-
•S10-
Industry E3 Companies
Percent of Waste Recycled Since 1992
283
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China Grove Textiles, Inc. chose to teach young children about environmental preservation by
inviting 60 fourth graders and their teachers to tour one of its plants. The children received an
overview of the manufacturing process. In addition, they were told about the importance of
reducing the amount of waste that is going to landfills and how they could help in that effort
by recycling items at home.
Dyersburg Fabrics Inc. is active with the Boy Scouts of America, assisting young scouts in
obtaining their environmental merit badge. The company also works with the National Bottling
Association recycling plastic beverage bottles to make fabric from soda bottles.
SARA 313 FORM R
REDUCTIONS
USTCD CHEMICALS EMITTED
Springs
1987 1988 1989 1990 1991 1992 1993 1994 1995
Cleyn & Tinker International Inc. is involved in a
venture with its local Rotary Club to recycle paper,
cardboard boxes, cones and tubes. The company
recycled an average of 1,000 pounds of material a
month.
Guilford Mills, Inc. won the 1995 North Carolina
Governor's Award for Excellence in Waste Reduction.
The company won for the large business category
and is only one of three companies in the state to
have received an award in this category. Guilford
was recognized for its significant achievements in
reducing air emissions and recycling.
Milliken & Company received first place in the 1995 Keep America Beautiful National Awards
in the reduce, reuse, recycle category. Keep America Beautiful is a national, non-profit public
education organization that honors individuals and businesses that come up with ways to
reduce waste and conserve natural resources and energy. Milliken received the award for a
process it developed to clean, retexture and restyle used modular carpets so the carpets can be
reused in offices, public buildings and other commercial facilities rather than being disposed of
in landfills. In addition, Milliken & Company was recognized by the EPA for its outstanding
performance in EPA's 33/50 Program. This voluntary pollution prevention initiative challenged
companies to reduce their emissions of 17 toxic chemicals by 33 percent by 1992 and by 50
percent by 1995. Milliken reduced its emissions by 94 percent in 1995.
Renew America, a national environmental organization, recognized Springs Industries, Inc. as
a national leader for its chemical reduction program and listed the program in its Environmental
Success Index. In 1995, Springs reduced toxic chemicals it used by more than 96 percent. This
is the second consecutive year Springs has been honored by the environmental organization.
(See chart above.)
284
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Thomaston Mills, Inc. and Forstmann & Company, Inc.'s Louisville, Ga., facility both received
awards from the Georgia Water & Pollution Control Association (GWPCA) for having out-
standing industrial biological wastewater treatment plants. The award is presented to indus-
trial facilities that consistently demonstrate outstanding performance. This is the third time the
Louisville facility has received.an award from GWPCA.
THE E3 PROGRAM.-
ENSURING A CLEAN AND COMPETITIVE TEXTILE INDUSTRY
I he E3 program has become one of the textile industry's most successful programs. It has
changed the way companies look at their business operations by making them more aware of
their environmental responsibilities. By becoming an E3 member, companies are saying that
environmental preservation is the responsibility of everyone — employees, companies,
communities and governments.
Protecting the environment for future generations also requires the U.S. textile industry to
think globally. ATMI has been active in working with foreign governments and private
organizations to develop stronger, more credible environmental labeling programs.
ATMI has also been active in developing international environmental standards, such as the
International Standards Organization (ISO) 14000. The intent of ISO 14000 is to create an
environmental standard that applies to all countries and minimizes trade barriers.
An example that typifies how committed companies are to the E3 program is the story of
Maiden Mills Industries, Inc. In December 1995, a fire destroyed 90 percent of its facility in
Lawrence, Mass. In the course of rebuilding, Maiden Mills has demonstrated that preserving
the environment is of the utmost importance.
The company believes in the philosophy of "sustainable development." Explains Walter
Bickford, the company's director of the environment, health and safety department, "In
addition to ensuring that our daily production processes don't compromise the environment,
we also look at the broader picture and the impact on the local community. We believe in
staying in the city and rejuvenating the urban economy rather than fleeing to the country to
greener pastures."
As a result, Maiden Mills chose to rebuild its turn-of-the-century riverfront factory. The
factory, which is in the inner city, is located in a nationally registered historic district. That
meant rebuilding to stricter, more expensive standards and actually expanding to rehabilitate
evacuated hazardous waste sites adjacent to the property.
"We want to maintain
a healthy business
without compromising
the environment
for future generations."
— Walter Bickford,
director of the environment,
health and safety department,
Maiden Mills Industries, Inc.
285
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As part of the estimated $300 million cost to rebuild, the company is paying particularly close
attention to energy conservation and waste reduction. "Being in New England, we're at the
end of the energy pipeline," says Bickford. "Our winters are cold, and we use a tremendous
amount of energy. Naturally, cost .savings is important to us, but saving energy and raw
materials are just as important."
With that in mind, the company is buying state-of-the art equipment that is more energy
efficient. Also, teams of employees and managers are working together to change machine
'' ' Jit
and process operations, which have reduced the amount of dye the company uses in its
manufacturing operations by 30 percent.
Bickford sums up the company's involvement in E3 in this way: "We want to maintain a
healthy business without compromising the environment for future generations." m
286
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E3 MEMBER COMPANIES — 1995
ALABAMA
NEW YORK
Russell Corporation
Alexander City,AL
Wellington Sears Company
(as of 1996, a division of
Johnston Industries, Inc.)
Valley, AL
GEORGIA
Avondale Mills, Inc.
Monroe, GA
Belding-Heminway Co., Inc.
New York, NY
Bloomsburg Mills, Inc.
New York, NY
Cleyn& Tinker
International inc.
New York, NY
Frank Ix & Sons, Inc.
New York, NY
Forstmann & Company, Inc. NORTH CAROLINA
Harriet & Henderson Yarns
Henderson, NC
The New Cherokee
Corporation
Spindale, NC
Pharr Yarns, Inc.
McAdenville, NC
Sara Lee Knit Products
Winston-Salem, NC
Shuford Mills, Inc.
Hickory, NC
Graniteville Company
Graniteville, SC
Hamrick Mills
Gaffney, SC
Inman Mills
Inman, SC
The Kent Manufacturing
Company
Pickens, SC
Mayfair Mills, Inc.
Arcadia, SC
Dublin. GA
Johnston Industries, Inc.
Columbus, GA
Southern Mills, Inc.
Union City, GA
Swift Textiles, Inc.
Columbus, GA
Thomaston Mills, Inc.
Jhomaston, GA
Wehadkee Yarn Mills
West Point, GA
WestPoint Stevens Inc.
West Point, GA
KENTUCKY
Fruit of the Loom, Inc.
Bowling Green, KY
MASSACHUSETTS
Maiden Mills
Industries, Inc.
Lawrence, MA
American & Efird, Inc.
Mount Holly, NC
Armtex, Incorporated
Pilot Mountain, NC
Artec Industries, Inc.
Shelby. NC
Borden Manufacturing
Company
Goldsboro, NC
Burlington Industries, Inc.
Greensboro, NC
Carolina Mills, Inc.
Maiden, NC
China Grove Textiles, Inc.
Gastonia, NC
Coats American
Charlotte, NC
Collins & Aikman
Products Co.
Charlotte, NC
Cone Mills Corporation
Greensboro, NC
Dominion Yarn
Corporation
Landis, NC
Fieldcrest Cannon, Inc.
Kannapolis, NC
Guilford Mills, Inc.
Greensboro, NC
Stonecutter Mills Corp. Milliken & Company
Spindale, NC Spartanburg, SC
Unifi, Inc. Mount Vernon Mills, Inc.
Greensboro, NC Greenville, SC
OREGON ?Partan Mill!L
Sparlanburg, SC
Pendleton Woolen Mills
Portland, OR Springs Industries, Inc.
Fort Mill, SC
PENNSYLVANIA
^ . — »..,. . TENNESSEE
Sun bury Textile Mills, Inc.
Sunbury, PA Dixie Yarr)s. Inc-
Chattanooga, TN
SOUTH CAROLINA Dyenburg Fabrics Inc
Alice Manufacturing Dyersfaurg. TN
Co., Inc.
Eos/ey. SC VIRGINIA
Arkwright Mills Dan River lnc-
Spartanburg SC Danville, VA
1996 NEW E3 MEMBERS
The following ATMI companies became E3
members in 1996:
The Amerbelle Corporation
Vernon, CT
Bradford Dyeing Association
Westerly, Rl
Weave Corporation
Hackensack, Nj
Greenwood Mills, Inc.
Greenwood, SC
287
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E3 PROGRAM COMMITTEE MEMBERS — 1995
GENERAL CHAIRPERSON
WilliamJ.Armfield.lV
Unifi, Inc.
ADVISORY BOARD CHAIRPERSON
Charles Tewksbury
Institute of Textile Technology
(retired)
VICE CHAIRPERSON
Patricia Jerman
South Carolina Wildlife Federation
MEMBERS
Robert A. Barnhardt
College of Textiles,
North Carolina State University
Paul Bowers
Georgia Power
Harry Dalton
South Carolina Sierra Club
Patricia Dillon
The Gordon Institute, Tufts University
E. Bruce Harrison, APR
£. Bruce Harrison Company, Inc.
Linda Rimer
North Carolina Department of
Environment, Health and
Natural Resources
Robert Stone
Lev/ Strauss, Inc. (deceased)
TASK FORCE
CHAIRPERSON
Donald Huffman
DMe Yarns. Inc.
VICE CHAIRPERSON
R. Nick Odom, Jr.
Springs Industries, Inc
MEMBERS
Martha Bonsai Day
Joshuo L. Baity & Co., Inc.
Bryant Haskins
Burlington Industries, Inc
John Hightower
Thomastan Mills, Inc
James Keesler
Arkwright Mills, Inc.
T. Halliburton Wood
Wellington Sears Company
288
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E3 PROGRAM COMMITTEE MEMBERS— 1996
GENERAL CHAIRPERSON
Gerald B. Andrews
Johnston Industries, Inc.
ADVISORY BOARD CHAIRPERSON
Patricia Jerman
South Carolina Wildlife Federation
VICE CHAIRPERSON
Larry Martin
American Apparel
Manufacturers Association
MEMBERS
Gay Ion T. Booker
National Cotton Council of America
Paul Bowers
Georgia Power
Harry Dalton
South Carolina Sierra Club
Patricia Dillon
The Gordon Institute, Tufts University
Gregory Poole
The Gap, Inc.
Linda Rimer
North Carolina Department of
Environment, Health and
Natural Resources
Michael T. Waroblak
Institute of Textile Technology
TASK FORCE
CHAIRPERSON
Donald Huffman
Dixie Yarns, Inc.
VICE CHAIRPERSON
R. Nick Odom, Jr.
Springs Industries, Inc.
MEMBERS
Bailey Barefoot
Swift Textiles, Inc.
Bryant Haskins
Burlington Industries, Inc.
James Keesler
Arkwright Mills, Inc.
Arthur Toompas
Cone Mills Corporation
T. Halliburton Wood
Johnston Industries, Inc.
289
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Index
References in bold type indicate a general discussion of
the entry topic.
accounting
barriers to pollution prevention from, 245
changes needed due to dyebath ratio changes,
183-184
computer modeling to assist in, 245-246
pollution prevention activities, role in incorporating, 244
waste audit, role in, 231
air pollutants, 11. See also indoor air quality (IAQ) problems
from boilers, 11, 14
from dyeing operations, 180
from finishing operations, 201
fugitive sources of, 11, 14
from heatsetting, 173
measurement of, 46-47, 236
from ovens, 14, 15
point sources of, 11, 14
prevention of, 16, 48-50
as primary emitters, 15
from printing, 47-48, 193, 196, 197
regulation of, 44-46
as secondary emitters, 15
from solvent-based cleaning activities, 14
sources of, 11, 14-15, 47
from spills, 14
from storage tanks, 14
types of, 46
from warehouses, 14
from wastewater treatment systems, 14
alternative technologies for pollution prevention
for coating systems, 98-99
cold processes, 99-100
in finishing, 205
in printing, 118, 196
in scouring and dyeing, 50, 116-118
waterless, 74
American Association of Textile Chemists and Colorists, 85,
86
buyer's guide, 138, 139, 201
American Textile Manufacturers Institute (ATMI)
pollution prevention ideas, as source of, 85
solid waste subcommittee of, 20
aquatic toxicity
from biocides, 62-63
causes of 57-59, 60
dyes in, role of, 60-61
from miscellaneous toxic compounds, 64
from pesticide residues, 63, 124
pollution preventions strategies for, 61, 64,175
from salt, 62
from sizing and desizing operations, 164
from surfactants, 61-62, 145-146, 174-175
synthetic and regenerated fibers, from processing of,
125-126
testing for, 57, 59, 105
from toxic anions, 63-64
from toxic organic chemicals, 62
audit. See also waste audit
of air pollutants, 235-236
of fabric preparation procedures, 174
of hazardous waste, 26
of machinery and operations, 86-88, 204
sizing/desizing operations, of waste from, 167
of solid waste, 22
walkthrough, of facility operations via a, 222
of wastewater, 17
automated chemical systems
capabilities of, 101, 102, 106, 107, 201, 215-216
for color mixing and batching, 185-186
for dosing of dyes, 185
for finishing operations, 206
maintenance of, 88
for print paste makeup, 196-197
barriers to practicing pollution prevention, 242-244, 245-246
batch processes
all-in dyeing with fiber reactive dyes, 36-37
vs. continuous processes in dyeing, 178-179
vs. continuous processes in fabric preparation,
171-172
dyeing with, described, 129
exhaustion/fixation levels with, 129-131
low-bath-ratio dyeing for, 111-112, 183-185
pollution prevention techniques for, 38,183-185
salt use in, 40-41, 44
single-step, cold-batch method to combine several
steps, 176
two-step dyeing with fiber reactive dyes, 36
biological oxygen demand. See BOD and COD
bleaching
by combining with scouring/desizing in single-stage
processing, 176
continuous knit bleaching ranges, use of, 176
fabric preparation, role in, 172-173
pollution concerns of, 173
291
-------
BOD and COD
biodegradability, as measures of, 90
cotton, levels in raw, 123-124
from dyeing operations, 179-181
handbuilders, levels from, 141
pollution prevention strategy for, 174, 263
preparation processes, levels from, 174
from printing operations, 192-193
of selected chemicals, 92
sewer fees based on, 93, 242-243
sizing and desizing, loadings from, 140-141,146,164,
172
surfactants, levels from, 144-145,172
synthetic and regenerated fibers, from processing of,
125-126
testing for chemical specialties, 103
from textile industry, 17-19
waste treatment systems, effect on, 51
broadwoven mills, 1
CAAA. See Clean Air Act Amendments
capital investment, 3
carcinogenfcHy/mutagenicity
of dyes, 135-136
of formaldehyde-containing resins for permanent
press finishing, 203-204
carding machine in natural fiber preparation, 4
carpetmaking
foam in, use of, 205-206
installation of carpets, pollutants associated with, 210
mothproofing in, pollution issues from, 207-208
pollution prevention opportunities in, 169-170
tufting in, 6
categorization of textile industry
general, 2
in Standard Industrial Classification (SIC) Manual, 2,
11,12-14
categorization of waste in textile industry, 31
cellulosic fibers, manufacture of, 4
chemical commodities
bulk systems/automated dispensing for, 151-152
categories of, 150-151
contaminants in, 150
metal impurities in, 55
pollutants and waste streams associated with, 150
pollution prevention ideas for, 150,151-152
prescreening for, 102-103
preventing hazardous waste from, 26-27
quality control for, 102-103,151
chemical handling
automated systems for, 101-102
employee training for, 101,197, 214-215
measuring for proper, 101
mixing for proper, 101
optimizing practices for, 100-102
packaging for proper, 100
purchasing practices for proper, 100
receiving practices for proper, 100
storage in, proper, 100-101
chemical measuring and dispensing devices. See a/so
automated chemical systems
accuracy, to ensure, 101
automated color kitchens, 185-186,196-197
automated mix kitchens, 106,107, 215-216
capabilities of, 106
dosing systems, 106, 108-109, 185
maintenance of, 88
chemical mixing areas
automated chemical dispensing systems in, 215-216
cleanup practices in, 215
design features of, 101, 214
employee work practices in, 214-215
implements in, use of proper, 215
mix tank design in, 215
chemical specialties
BOD testing for, 103
builders (or handbuilders), 141
categories of, 138, 139, 140
obtaining information from vendors for, 147-148
packaging for, selecting, 149-150
for permanent press finishes, 141
pollutants and waste streams associated with, 137-138
pollution prevention ideas for, 137-138, 146-150
prescreening of, 103, 148-149
preventing hazardous waste from, 26-27
proprietary nature of, 138-139, 243
quality control for, maintaining, 149
softeners, 141
surfactants, 141-146
warp sizes, 140-141
chemical substitutions
BOD and COD of, 90, 92, 93
decision to use, factors affecting, 89, 92, 243
for formaldehyde-containing resins, 202-203
for handbuilders, 203-204
for hard-to-treat wastes, 32
for mothproofing chemicals, 207-208
for phosphates, 92-93
for softeners, 203
for solvents, 93-94
obtaining information on, 89-91
prescreening for commodities, 102-103
prescreening for specialties, 103, 148-149
rationale for, 88
types of, 91
Clean Air Act Amendments (CAAA)
air toxics under, major sources of, 11
hazardous air pollutants (HAPs) identified in, 44-46
impact on textile industry, 44, 46
cleaning and maintenance chemicals
control of, 97
environmental problems with, potential for, 97
examples of, 97
solvents, 97
color in dyeing wastewater
characteristics of, 34
fiber reactive dyeing in, role of, 35-37, 133
measurement of, 34
prevention and minimization of, 35-36
reduction through use of fixatives, 37
sources of, 34, 243
colour index for dyes, 136-137, 243
combing machine in natural fiber preparation, 4
consumer care of textile products, 105-106, 210, 211
292
-------
. continuous processes
vs. batch processes in dyeing, 178-179
vs. batch processes in fabric preparation, 171-172
countercurrent washing for fabric preparation using,
175
dyeing with, described, 129
for dyeing knits, 109, 110
horizontal washers for energy and water conservation,
175
knit bleaching ranges for pollution prevention, 176
pollution prevention techniques for, 38, 185-186
quick-change padders for, 113, 114
salt needs for, 41
corporate policy on pollution prevention, 219-220, 241-242
cotton
BOD and COD levels found in, 123-124
* carding of, 4
combing of, 4
metal levels found in, 123-124
opening/blending bales of, 3-4
pollutants in, 122-124
pollution prevention in spinning of, 157-159
roving of, 4
salt use in processing of, 42
sorting and cleaning of, 4
spinning of, 4
design-stage planning for pollution prevention
chemical prescreening, 102-104
chemical selection, 80-81, 196
for facilities, 83-84
globalization of, 81
machinery selection, 80
for printing, 195
for processes, 79-80
for products, 81-83
questions to ask in, 79
to reduce salt use, 42
standardization of pollution prevention efforts, 105
substitute mechanical processes for chemical
processing, 81, 82-83, 147
desizing. See also sizing
aquatic toxicity from, 164
BOD loadings from, 164
combined with scouring/bleaching in single-stage
processing, 176-177
described, 163
fabric preparation, role in, 172
fiber lint and yarn waste from, 165
pollutants and wastes associated with, 163-165
pollution prevention measures associated with,
165-168, 172
with water-soluble vs. water-insoluble sizes, 172
dispersible wastes
examples of, 31
pollution prevention principles for, 31-32
from printing, 193
risk assessment methods, role in, 244-245
sources of, 31 -32
drafting. See roving
dry capture in printing operations, 197
dryer efficiency
air pollution improvement from, 106-107
from humidity sensors, 110-111, 204
from incinerators, 111
dry spinning
described, 4
fibers formed by, 4
dyeing, 6. See also batch processes; continuous processes;
dyes
batch vs. continuous, 179
cloth or piece, 178-179
dyes used in, types of, 132-134, 180-183
environmental concerns from, 129
fiber, 178
machines used in, types of, 7, 8-10, 107-108, 179
metals in effluent, as source of, 53-54
pollutants and waste streams associated with, 176,
179-180
rope vs. open-width, 179
salt requirements of machines used in, 41
scheduling operations to minimize machine cleaning
from, 104
types of, 129-132, 179
with ultra-low-liquor-ratio techniques, 40-41, 111-112,
183-185
yarn, 178
dyeing, pollution prevention measures for, 176
with batch processes, 183-185
better controls, implement, 191
chemical auxiliaries, minimizing use of, 186
with continuous processes, 185-186
dyebath reuse, 107-108, 189-191
dye fixation, improving, 186
pad-batch dyeing, 186-188
right-first-time dyeings, 186
with specific dyes, 180-183
water reuse, 191
dyes, 127-129
acid, 132, 180
azoic, 132
basic, 132-133, 182
carcinogenicity/mutagenicity of, 135-136
chrome, 180-182
classes of, 132
colour index (Cl) for, 136-137, 243
direct, 133
disperse, 133, 182
end-use classes of, 134-135
environmental concerns from, 129, 243
fiber reactive, 36-37, 133, 182-183
metals in effluent, as source of, 52-53, 54
mordant, 134 *
pad-batch dyeing, used in, 187
pigments, 134
pollutants associated with, 127-128, 179-181
pollution prevention ideas for, 127-128, 136-137,
180-183
sulfur, 134, 183
for ULLR dyeing, 184
vat, 134
293
-------
effluent. See wastewater
electrolytes. See salts
energy savings. See also heat recovery
cold processes, by using, 99-100
examples of, 259, 264
by minimizing wet pickup, 94-95
environmental friendliness
choosing dyes for, 134-135
designing products for, 81
educating and influencing consumers with information
on, 105-106, 241
misrepresentations of, 104,105
PRIMA system, comparing suppliers with, 240
Enviro$en$e bulletin board, 220
equipment maintenance
auditing, 86
checklists for, use of, 86-87
common defects, 87
printing operations, for pollution prevention in, 196
slashing operations, for pollution prevention in, 168
equipment for pollution prevention
automated mix kitchens, 107
built-in bath reuse on dye machines, 107-108
chemical dosing systems, 108-109
chemical recovery, 108,109
compacting, 112-113
continuous knit dyeing ranges, 109,110
control, automation, and scheduling management
systems, 109-110,111
countercurrent washing, 110
heat recovery, 110
humidity sensors in drying, 110-111
incinerator dryer, 111
laser engraving of printing screens, 114
low add-on finishing, 114-116
low-bath-ratio dyeing systems, 111-112
pad-batch dyeing, 187
quick-change padders on continuous ranges, 113, 114
transfer printing, 113,115
waste reclamation in spinning, 116
water recovery, 116
fabric preparation
alkaline waste streams from, 174
bleaching, 172-173
continuous vs. batch processes, 171-172
desizing, 172
equipment for preventing pollution in, 175-176
heatsetting, 173
mercerizing, 173
pollutants and waste streams associated with, 170-171
pollution issues related to, 171
pollution prevention strategies for, 170-171, 173-176,
177
right-first-time dyeings, role in, 186
scouring, 172
singeing, 173
fabric production, 1. See also carpetmaking; knitting;
weaving
cutting room waste from, 209
cutting, sewing, product fabrication, 208-210
pollutants and waste streams associated with, 168
pollution prevention ideas for, 168, 209-210
fats, oil, and grease (FOG)
in natural fibers, 122
from printing paste in wastewater, 193-194
in wool, 124
fiber reactive dyes
batch dyeing with, 36
described, 133
environmental concerns about, 133
high fixation techniques for, 37
pad-batch dyeing with, 113
poor fixation in, 36
fiber reactive print pastes
replacing urea in, 197-198, 199
shelf life of, 197
fibers, 11. See also manmade fibers; natural fibers
contaminants in, 122, 125-126 *
conversion into yarn, 5
dyeing of, 178
pollutants and waste streams associated with, 121-122
pollution prevention measures for, 121-122, 126-127
preparation of, 3-4
research and development for, 3
sources of, 1
testing of incoming, 122
tow, 1
filters
proper maintenance of, 87-88
finishing, 1
atmospheric emissions from, pollution prevention for,
201
chemical alternatives for, 201-204
chemically-imparted characteristics, types of, 7, 11
chemical specialties for, use of, 140
cotton, cellulosic, synthetic fibers, pollution prevention
for, 201-206
equipment to minimize pollution, 204
fabric design to minimize, 202
fabric handling to minimize, 202
liquid wastes, pollution prevention for, 200-201
with low add-on methods, 114-116, 204, 205
mechanical alternatives for, 74, 202, 204-205
optimization of processes for, 202
physical methods, types of, 7
pollutants and waste streams associated with, 199,
200
pollution prevention ideas for, 199, 200-208
solid wastes, pollution prevention for, 200
wool, pollution prevention for, 206-208
FOG. See fats, oil, and grease
globalization of pollution prevention, 105-106,124,134-135,
247
barriers to, 212
communication in, role of, 105-106, 212-214, 240-241
customer involvement for, 81, 82,105-106
for dyeing operations, 176, 178
to minimize chemical processing, 212
need for, 211
participants in, 212
pollution prevention teams incorporate, 222,223-229
for preparation processing operations, 212
294
-------
for sizing and desizing operations, 146,165
vendor involvement for, 105-106, 149
greige (or gray goods), 1, 128, 171
hard-to-treat wastes, 32
examples of, 32
pollution prevention strategies for, 32-33
from printing, 193
problems that arise from, 50-52
risk assessment methods, role in, 244-245
sources of, 32
treatability of, improving, 50
hazardous air pollutants (HAPs), 27
CAM, identified by, 44-46
design products to avoid, 48-49
specific to textiles, 46
hazardous wastes, 24
disposal of, 25
examples of, 33
generation and storage of, 24-25
handling and recordkeeping of, 26
policies for, 24
prevalence of, 24
from printing, 193
regulations for, 25, 26
risk assessment methods, role in, 244-245
from solvent-coating operations, 25-26
sources of, 25-26
heat recovery, 110, 259, 264. See also energy savings
heatsetting in fabric preparation, 173
high-extraction, low-carryover processes
in afterwashing of prints, 196
devices used in, 96
offensive materials, recovery of, 96
process step separations, 95-96
wet-on-wet processing, 95
wet pickup, minimizing, 94-95
high-volume wastes, 33
examples of, 33
from printing, 193
risk assessment methods, role in, 244-245
incentives to practice pollution prevention
for companies, 239-241
for employees, 230, 235, 246
indoor air quality (I AQ) problems, 15
from drapery linings, 15
from drapery materials, 15
from finishing chemicals, 15,16
OSHA rule for, 15
prevention of, 16, 210-211, 261
integration of producers
backward, 3
forward, 3
need for, 239
vertical, 172
ISO 14000 environmental standards, 239
knitting, 5-6
pollution prevention in, 169
warp, 1,6
weft, 1,6
looms
air-jet, 5
components of, 5
projectile, 5
rapier, 5
shuttle, 5
shuttleless, 5
water-jet, 5
machinery, 3-11. See also equipment for pollution prevention
management systems
for control, automation and scheduling, 109-110, 111
for real-time process monitoring and control, 116-118
manmade fibers. See also synthetic fibers; cellulosic fibers
companies responsible for production of, 3
manufacture of, 4
types of, 11
markets for wastes. See also waste exchanges
as business opportunities, 241
development of, 97-98
from finishing operations, 200
from printing process, 196
for silver, 198
Material Safety Data Sheets (MSDS)
chemicals from typical finishes as listed in, 15, 16
chemical specialties, role in purchasing, 138-139
metal content, use in determining, 53
prescreening, use in, 26, 27, 49, 103
problem solving, use in, 147
toxicity of chemicals, use in determining, 59, 64
mechanical substitutions for chemical processing
compacting, 112-113
in finishing operations, 74, 201-202, 204-205
for knit designs, 82-83
to prevent hard-to-treat wastes, 32
in sizing operations, 166-167
types of, 81, 147
melt spinning
described, 4
fibers formed by, 4
mercerizing, 173
dye fixation, to improve, 186
fabric preparation, role in, 173
vat dyes, role when used with, 134
waterless, 74
metals in effluent
chemical sources of, 55-56
from cotton, 123-124
dyeing process sources of, 53-54, 179
dye sources of, 52-53, 54, 180-183
from fabric preparation, 175
plumbing sources of, 55
pollution prevention strategies for, 56-57, 175
from printing, 194
synthetic and regenerated fibers, from processing of,
125-126
MSDS. See Material Safety Data Sheets
National Pollutant Discharge Elimination Standards (NPDES)
chloride limits of, 40
general discharge limits of, 17
pH limits of, 174
295
-------
natural fibers. See also cotton; wool
contaminants in, 122
preparation of, 3-4
sources of, 122
types of, 11
NPDES. See National Pollutant Discharge Elimination
Standards
Occupational Safety and Health Administration IAQ rule, 15
openers
In cleaning natural fibers, use of, 4
OSHAIAQrule,15
overmMng, 206
packaging
bulk systems for chemical commodities, use of, 83,
100,151-152
for chemical specialties, 100,149-150
for salts, 42
for size, 167
pad-batch processes
as alternative for fiber reactive dyeing, 183
for combined single-stage processing, 176
vs. conventional dyeing processes, 187
costs of vs. batch and continuous processes, 187-188
dye and equipment requirements of, 187
with fiber reactives, 70,113
as pollution prevention measure, 186-188
salt needs for, 41
substituting for another process, 32
pentachlorophenol (PGP)
levels in carpets, 124
levels in wool, 124-125
pesticide residues
from cotton, 122-124
from wool, 124-125
plied yams, formation of, 5
Pollution Prevention Information Clearinghouse, 220
pollution prevention of air pollution
air emissions from printing operations, by minimizing,
196,197
air pollutants from finishing operations, by minimizing,
201
audit information for, 235-236
boiler operations for, optimizing, 49
by chemical auxiliary elimination, 49
chemical prescreening for, 49,102-104
chemical and process alternatives, by using, 256
emerging technologies, by investigating, 50
fiber prescreening for, 49
hydrocarbon release from printing operations, by
minimizing, 193
by product design examination, 48-49
by quality control assurance of incoming fibers,
126-127
solvent processing operations, by improving, 49-50
by source identification and emissions quantification,
49
by spill prevention, 50
solvent recycling for, 257, 265
strategies for, 15-16
trapping bulk storage tanks for, 49
pollution prevention of hard-to-treat wastes
by chemical or process substitution, 32
employee work practices, by improving, 33
process control and optimization, by improved, 33
treatability, by improving, 50-52
by waste segregation, capture, and reuse/recycle, 33
pollution prevention of hazardous waste
barriers to, 243-244
chemical and process alternatives, by using, 256
prescreening chemicals for, 26,102-104
rationale for, 24
by recycling solvent, 265
screening and reviewing processes in, 27
strategies for, 26-27
testing raw materials for, 27
pollution prevention of indoor air pollution
considerations for, 210
consumer issues for, 211
strategies for, 16,105-106, 261
pollution prevention for salt reduction
by batch dye bath reuse, 44
low bath ratios, by using, 40-41
by optimizing salt use, 41-42, 43
by process design, 42, 43
by product design, 42
by proper handling, 42
pollution prevention of solid wastes
for ash and sludge, 21
for bags, 21, 24
by cost factor evaluation, 22, 23
by disposal, 22
for drums, 21, 24, 200, 252-253
for fibers and fabric, 23, 200
general focus of, 20
by marketing of wastes, 260
for miscellaneous items, 24
for packaging materials, 21, 149, 252-253, 262
for pallets, 23, 252-253
for paper and cardboard, 21, 23
for processing wastes, 21-22
by recycling, 22, 252-253
by reuse, 22,197
by source reduction, 22
waste management practices in, use of, 22-23
pollution prevention of water pollution
by aquatic toxicity reductions, 61, 64, 261
barriers to, 243-244
bulking and poor settleability, by reducing, 51
by chemical prescreening, 102-104,139, 146, 251,
266, 270, 271
chemical and process alternatives, by implementing,
256, 263
by chemical recovery and reuse, 108,109, 257, 265,
269
color in wastewater from batch dyeing, by reducing, 38
color in wastewater from continuous dyeing, by
reducing, 38
drum washing, by eliminating, 201
dyebath exhaustion, by maximizing, 35, 251
dyebath reuse, by implementing, 72, 107-108,
189-191,250,254
296
-------
by dye handling, equipment cleaning, and
housekeeping techniques, 36
fixation and washoff, by maximizing, 35
metals in effluent, by reducing, 56-57, 124, 271
pass-through of nondegradable materials, by
reducing, 52
priority areas for, 20
by process water reuse, 70-72, 191, 252-253, 255,
268
by quality control assurance of incoming fibers,
126-127, 251
respiratory inhibition, by reducing, 51
salts in wastewater, by reducing, 40-44, 113
shock loading, by reducing, 52
. sludge contamination, by reducing, 51
targets for, 17, 19
treatability, by improving, 50-52
permit limits, role of, 17-19
by waste stream segregation, 106
water conservation techniques, by implementing,
67-74, 258, 263, 264, 266, 268
work practices/scheduling, by using sound, 38, 267
pollution prevention programs, characteristics of
coordinator, 220
employee commitment, 77, 219-220
long-term commitment, 78
management commitment, 77, 219-220, 241-242
standardization, 105
team to lead, 220-221
pollution prevention programs, responsibilities of
action plans, developing, 222, 230-231
costs of specific techniques, evaluating, 235
documenting accomplishments, 78
employee input, .encouraging, 88, 230
general strategies, 78
high-technology approaches, 78
implementing strategies, 219
low-technology approaches, 77-78
pollution prevention plan, development of, 221
process mapping, 221-222, 223-229
proper scheduling, 104
right-first-time production, 79
risks/liabilities of managing waste streams, evaluating,
235, 244-246
setting goals for, 222
technical feasibility of specific techniques,' evaluating,
234-235
waste auditing, 231-238
waste minimization techniques, monitoring, 235
waste reduction techniques, choosing, 233-235
POTW. See publicly owned treatment works
printing, 6.
color in wastewater from, 38
direct, 6
discharge, 6, 192, 194
dispersible wastes from, 31, 193
heat-transfer, 6
ink jet, 118, 195
jet, 6
laser engraving of screens for, 114
pollutants associated with, 47-48, 191, 192-193
pollution prevention by minimizing oil/hydrocarbon
discharge, 193-194
pollution prevention practices for, 191,195-199
pollution prevention strategies for, 193-195
resist, 6
silver in, use of, 198
techniques, 191-192
toxic air emissions from, 47-48
transfer, 113, 115, 194-195
warp, 6
process alternatives
cold batch processes, 99-100,176, 186-188
design stage planning, 79-81
examples that can reduce pollution, 99,147
to improve control, 106-107, 109-110, 111
mechanical substitutions for chemical processes, 81,
112-113, 147
to minimize pollution from sizing operations, 166-167
to minimize WPU, 94-96, 205
powder coatings to replace solvent-based coatings,
98-99
to prevent hard-to-treat wastes, 32
process flow diagram. See process mapping for pollution
prevention
process mapping for pollution prevention, 221-222, 223-229
publicly owned treatment works (POTW)
limits imposed on, 38-39
pH limits imposed by, 174
surcharges imposed by, 19, 20, 93, 242-243
wastewater directed to, 17
quality control. See also raw material quality control
of chemical commodities, 151
chemical prescreening for, 102-104
of chemical specialties, 149
of fibers for contaminants, 122, 124, 126-127
with formal evaluation structures, 104
of raw materials, 27, 96-97, 173-174
of sizing operations, 146, 167
standardization of, 105, 213
testing as key to purchasing procedures for, 100
of warp size and yarn, 167
of wool, 124-125
raw material quality control
as a pollution prevention strategy, 96-97, 173-174
prescreening chemicals for, 100, 102-104
with formal evaluation structures, 104
for warp size, 167
regenerated fibers
pollution concerns for, 125-126
types of, 125
research and development, 3, 237
risk assessment methods, 244-246
roving
in natural fiber preparation, 4
salts, 38-39
dyeing processes, use in, 39-40
from fiber reactive dyes, 133
pollution prevention practices for reduction of, 40-44 '
quantities used in textile operations, 38, 39
297
-------
regulatory status of, 40
requirements for various dye classes, 41-42
sources in wastewater, 39
types used in textile operations, 39
scheduling
with automated systems, 106-107
of dyeing operations for pollution prevention, 38,104
of finishing operations for pollution prevention, 206
of sizing operations for pollution prevention, 167
scouring
fabric preparation, role in, 172
pollution concerns with, 172
singeing, pollution potential, 173
sizing. See a/so desizing
application of, 5
auxiliary chemicals used for, 140,163
chemical recovery from, 108,109,165-166
described, 160-161
equipment used in, 161
pollutants and waste streams associated with, 159-160
pollution prevention measures for, 146,159-161,
165-168
primary components of chemicals used for, 161-163
recycling/recovering of size, 165-166
semlsynthetfc products for, use of, 140
starch for, use of, 140,162
synthetic products for, use of, 140
warp sizes used in, 140-141,161-163
wastes generated by materials used in, 164-165
slashing. See sizing
sliver
described, 4
role in combing, 4
sludge
contamination of, 51-52
hard-to-treat wastes that pass through treatment
systems, 193
metals from natural fibers in, 122
solid waste, as component of, 20, 21
solid wastes, 20
cutting room waste, 208-209
pollution prevention of, 159
pollution prevention practices to reduce cutting room
waste, 209-210
from spinning operations, 156-157
sources of, 20-22
types of, 20,21
solvent
chemical substitutions involving, 93-94
pollution prevention for cleaning agents, 97
pollution prevention for solvent-based coating
systems, 98-99
processing operations for, improving, 49-50
spinning operations. See a/so dry spinning; melt spinning;
wet spinning
additives from, 157,159
controllable-cause waste from, 156
fiber waste from, 156
long staple system in, 155
in manmade fiber manufacture, 4
in natural fiber preparation, 4
pollutants and waste streams associated with, 153
pollution prevention ideas for, 153
pollution prevention in short staple system, 157-159
pollution prevention of solid waste from, 159
process waste from, 156
short staple system, 155-156
solid waste from, 156, 159
waste reclamation from, 116, 157,159
Standard Industrial Classification (SIC). See categorization
of textile industry
standardization of pollution prevention efforts
by incorporating ISO 14000 standards, 239-240
need for, 105
for tests, methods, definitions, 105
staples
cutting of filament yarns into, 154
role in yarn spinning, 1, 5, 155
surfactants
amphoteric, 143
anionic, 142-143
aquatic toxicity of, 145-146, 174-175
biodegradability of, 144
BOD and COD of, 144-145, 174
cationic, 143
chemical specialty formulations, use in, 141
nonionic, 142
pollutant properties of, 143-146
pollution prevention ideas for, 64,146-147, 175,
195-196
scouring, use in, 172
as toxic compounds, 61-64
uses of, 141, 143
synthetic fibers
contaminants in, 126
manufacture of, 4
pollution concerns for, 125-126
types of, 125
technology transfer of pollution prevention activities, 237
textile facilities
geographic distribution of, 2
types of, 2
textile products
types of, 11, 12-14
value of shipments for, 1,14
texturizing
of manmade fibers, 4
of spun yarns, 5
throwing in the production of filament yarns, 5
total quality management, 219, 239
total suspended solids (TSS)
calculating sewer fees, role in, 242-243
handbuilders, levels from, 141
raw textile dyeing wastewater, levels in, 17
training
for chemical handling, 33, 101, 214-215
formalized employee education, use of, 85-86,
236-237, 246-247
for slashing operations, 167
as key to pollution prevention program success,
84-85, 230, 236-237, 246-247
as tool to involve employees, 84-85, 219-220, 236-237
TSS. See total suspended solids
298
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tufting, 6
ULLR. See ultra low liquor ratio dyeing systems
ultra low liquor bleach range, 175
ultra low liquor ratio (ULLR) dyeing systems
bath ratio with, 111-112
conserving salt by, 40-41
costs of, 185
pollution prevention with, 183-185
volatile organic compounds (VOCs)
eliminating emissions from solvent-based coating
systems, 98-99
from heatsetting, 173
from installation and aftermarket treatments, 210
from solvents, 93
sources of, 46-48
warp yarns
role in weaving, 5
sizes applied to, 140-141, 160
waste audits. See also audit
approach to, 231
background information for, collecting, 232
forms and lists in, use of, 236
information gathered by, 233, 234
need for, 231
plant survey for, conducting, 232, 233
of sizing operations, 167
of solid waste, 22
waste stream sampling for, 232
for water, 64-65
waste exchange. See also markets for wastes
advertising for, 23
benefits of, 97-98
examples of materials for, 98
wastewater
aquatic toxicity of, 57, 125-126
audit of, 17
BOD and COD of, 125-126
characteristics of, 16-17
color residues in, 34-37
hard-to-treat wastes in, problems from, 50-52
mothproofing in, pollution prevention for, 207-208
metals in, 52-56, 125-126
multiple water handling systems for, 84, 106
permitted discharges of, 17, 19
Priority Pollutants list for, 57, 58-59
quantities of, 16, 17-19
recovery and reuse of, 116, 174
segregation and capture of, 84, 106
sources of, 66
surcharges applied to, 19, 20,147, 242-243
water conservation possibilities for, 65-67
water conservation
calculating sewer fees, role in, 242-243
in continuous dyeing operations, 186
countercurrent washing for, 67-68, 110
dye equipment for, 107-108
in dyeing operations through water reuse, 191
in fabric preparation procedures, 174
low carryover washing for, 68
in printing operations, 196, 199
rationale for, 64-65
recovery of water for, 116
reuse for cleaning, 68-69
strategies for, 67-74
types of wastewater offering possibilities for, 65-67
water pollution, 16-20. See also wastewater
wet pickup (WPU)
low add-on finishing to reduce, 205
reasons to minimize, 94, 95
saturation/expression process to reduce, 94
wet spinning
described, 4
fibers formed by, 4
weaving
of warp yarns, 5
pollution prevention in, 168-169
wool
carding of, 4
combing of, 4
chrome dyeing for, 180-183
mothproofing of, 96, 207-208
opening/blending bales of, 3-4
PCP levels in, 124-125
pollutants in, 124-125, 206
pollution prevention practices in finishing of, 207-208
roving of, 4
sorting and cleaning of, 4
spinning of, 4
yarn production
filament yarns, 1, 5, 153-154
pollutants and waste streams associated with, 152-153
pollution prevention ideas for, 152-153
spun yarns, 5, 154-155
299
* U. S. GOVERNMENT PRINTING OFFICE; 1SS7-S49-OO1/6012E
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