EPA-440/l-74-022-a
Development Document for Effluent Limitations Guidelines
and New Source Performance Standards for the
TEXTILE MILLS
Point Source Category
June 1974
s ^£2^ 1 U.S. ENVIRONMENTAL PROTECTION AGENCY
Wasliington, D.C. 20460
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DEVELOPMENT DOCUMENT
for
EFFLUENT LIMITATIONS GUIDELINES
and
NEW SOURCE PERFORMANCE STANDARDS
for the
TEXTILE
POINT SOURCE CATEGORY
Russell E. Train
Administrator
James Agee
Acting Assistant Administrator for Water and Hazardous Materials
ya"*r<».
Allen Cywin
Director, Effluent Guidelines Division
James D. Gallup
Project Officer
June , 1974
Effluent Guidelines Division
Office of Water and Hazardous Materials
U.S. Environmental Protection Agency
Washington, D.C. 20460
For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, D.C. 20402 - Price $2.65
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ABSTRACT
This document presents the findings of a study of the textile
manufacturing industry for the purpose of developing waste water
effluent limitation guidelines and Federal standards of performance
for new sources in order to implement Section 304(b) and 306 of the
Federal Water Pollution Control Act Amendments of 1972 (the "Act").
This study covers approximately 7,000 plants in S.I.C. 22.
Effluent limitations guidelines are set forth for the degree of
effluent reduction attainable through the application of the "Best
Practicable Control Technology Currently Available", and the "Best
Available Technology Economically Achievable", which must be
achieved by existing point sources by July 1, 1977 and July 1, 1983,
respectively. The "Standards of Performance for New Sources" set
forth the degree of effluent reduction which is achievable through
the application of the best available demonstrated control
technology, processes, or other alternatives.
The proposed regulations for July 1, 1977 and for new source
performance standards, require in-plant waste management and
operating methods, together with the best secondary biological
treatment technology currently available for discharge into
navigable water bodies. This technology is represented by
preliminary screening, primary treatment (wool scouring only),
coagulation (carpet mills only), and secondary biological treatment.
In addition, multi-media filtration or its equivalence for the
control of TSS is recommended for new sources.
The recommended technology for July 1, 1983 is in-plant waste
management and preliminary screening, latex coagulation (carpet
mills and dry processing only), primary sedimentation (wool scouring
only), biological secondary treatment and advanced treatment such as
multi-media filtration and/or chemical coagulation/clarification.
Supportive data and rationale for development of the proposed
effluent limitation guidelines and standards of performance are
contained in this report.
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CONTENTS
Section Page
I CONCLUSIONS 1
II RECOMMENDATIONS 3
III INTRODUCTION 7
Purpose and Authority 7
Methodology 8
General Description of the Industry 9
Profile of Manufacturing Processes -^
Wool Fiber and Fabric Finishing Operations 17
Cotton Fiber and Fabric Finishing Operations 19
Synthetic Fiber and Fabric Finishing Operations 21
Process Description by Subcategory 22
IV INDUSTRY CATEGORIZATION 35
Previous Approaches 35
Categorization 38
V WASTE CHARACTERISTICS 47
Subcategory 1 - Raw Wool Scouring 47
Subcategory 2 - Wool Finishing 49
Subcategory 3 - Dry Processing 52
Subcategory 4 - Woven Fabric Finishing 54
Subcategory 5 - Knit Fabric Finishing 65
Subcategory 6 - Carpet Mills 66
Subcategory 7 - Stock and Yarn Dyeing and Finishing 67
Subcategory 8 - Commission Finishing 67
VI SELECTION OF POLLUTANT PARAMETERS 69
Waste Water Parameters of Major Significance 69
iii
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CONTENTS (Continued)
Section
VI Rationale for Selection of Major Parameters 69
Biochemical Oxygen Demand 69
Chemical Oxygen Demand 70
Total Suspended Solids 70
Oil and Grease 71
Color 72
Chromium 73
Sulfides 73
Phenol 73
Fecal Coliforms 74
pH, alkalinity, and acidity 74
Rational for Selection of Minor Parameters 75
Total Dissolved Solids 75
Ammonia Nitrogen and Other Nitrogen Forms 76
Phosphates 76
Temperature 76
Other Heavy Metals 76
Toxic Organic Chemicals 77
VII CONTROL AND TREATMENT TECHNOLOGY 79
In-Process Control 79
New Process Technology 82
Specific In-Process Changes 85
Biological Treatment Technology 87
Performance of Biological Treatment Systems 94
Advance Waste Water Treatment Systems 98
Phase Change 99
Physical Separation 102
Sorption Systems 109
Chemical Clarification 119
VII COST, ENERGY, AND NON-WATER QUALITY ASPECTS 123
Cost and Reduction Benefits of Alternative 123
Treatment and Control Technologies
Basis of Economic Analysis 123
Cost Effectiveness of Treatment Alternatives 137
IV
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CONTENTS (Continued)
Section Page
VIII Impact of Waste Treatment Alternatives on 138
Finished Product
Alternative Treatment Systems 148
Electrical Energy Requirements 148
Thermal Energy Requirements 148
Solid Wastes 149
IX EFFLUENT REDUCTION ATTAINABLE THROUGH THE 151
APPLICATION OF THE BEST PRACTICABLE CONTROL
TECHNOLOGY CURRENTLY AVAILABLE EFFLUENT
LIMITATIONS GUIDELINES
Introduction 151
Effluent Reduction Attainable Through the 152
Application of Best Practicable Control
Technology Currently Available
Identification of Best Practicable Control 156
Technology Currently Available
Rationale for the Selection of Best Practicable 178
Control Technology Currently Available
Age and Size of Equipment and Facility 178
Total Cost of Application in Relation to 178
Effluent Reduction and Benefits
Engineering Aspects of Control Technique 178
Applications
Process Changes 178
Non-Water Quality Environmental Impact 178
Factors to be Considered in Applying Level I 179
Guidelines
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CONTENTS (Continued)
Section Page
X EFFLUENT REDUCTION ATTAINABLE THROUGH THE 181
APPLICATION OF THE BEST AVAILABLE TECHNOLOGY
ECONOMICALLY ACHIEVABLE EFFLUENT LIMITATIONS
GUIDELINES
Introduction 181
Effluent Reduction Attainable Through 182
Application of the Best Available Technology
Economically Achievable
Identification of the Best Available 182
Technology Economically Achievable
Rationale for the Selection of Best Available 187
Control Technology Economically Achievable
Age and Size of Equipment and Facilities 187
Total Cost of Application in Relation to 187
Effluent Reduction Benefits
Engineering Aspects of Control Technique 187
Application
Process Changes 188
Non-Water Quality Environmental Impact 188
Factors to be Considered in Applying Level 188
II Guidelines
XI NEW SOURCE PERFORMANCE STANDARDS 189
Introduction 189
Effluent Reduction Attainable for New Sources 189
Rationale for the Selection of New Source 189
Performance Standards
VI
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CONTENTS (Continued)
Section Page
XI Engineering Aspects and costs of Application 190
in Relation to Effluent Reduction Benefits
Pretreatment Requirements 190
XII ACKNOWLEDGEMENTS 193
XIII REFERENCES 195
Selected Reference Sunmaries 195
Bibliography 205
XIV GLOSSARY 221
XV APPENDICIES 229
XVI CONVERSION TABLE 241
vn
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TABLES
Numbers Page
1 Maximum Thirty Day Average 4
Effluent Limitation Guidelines for July 1, 1977
2 Maximum Thirty Day Average 5
Effluent Limitation Guidelines for July 1, 1983
3 Number of Textile Plants by Geographic Areas: 11-12
1967
4 Water Use by the Textile Industry 15
5 Water Discharged by the Textile Industry 16
; ,6 Industry Categorization 37
7 Types and Amounts of Dyes Used in the Textile 60
Industry
8 Chemicals Used in Application of Dyes 63-64
9 Expected Effluent Suspended Solids from Multi- 104
Media Filtration of Biological Effluents
10 Carbon Adsorption Pilot Plant: Average Water 113
Quality Characteristics
11 Accuracy of Standardized Costing Methodology 127
12 Waste Water Treatment Costs for Wool Scouring 141
Subcategory
Vlll
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TABLES
Numbers Page
13 Waste Water Treatment Costs for Wool Finishing 142
Subcategory
14 Waste Water Treatment Costs for Dry Processing 143
Subcategory
15 Waste Water Treatment Costs for Woven Fabric 144
Finishing Subcategory
16 Waste Water Treatment Costs for Knit Fabric 145
Finishing Subcategory
17 Waste Water Treatment Costs for Carpet Mills , 146
Subcategory
18 Waste Water Treatment Costs for Stock and Yarn, 147
Dyeing and Finishing Subcategory
19 Maximum Thirty Day Average Effluent Limitations 153
Guidelines for July 1, 1977
20 Performance of Biological Treatment Systems 155
21 Performance of Effluent Treatment Systems 157
Subcategory 1: Wool Scouring
22 Performance of Effluent Treatment Systems 158
Subcategory 2: Wool Finishing
23 Performance of Effluent Treatment Systems 161
Subcategory 3: Dry Processing
24 Performance of Effluent Treatment Systems 165
Subcateogy 4: Woven Fabric Finishing
25 Woven Fabric Finishing: Internal Subcategori- 168
zation for the Establishment of COD Limitations
26 Performance of Effluent Treatment Systems 171
Subcategory 5: Knit Fabric Finishing
27 Knit Fabric Finishing: Internal Subcategori- 172
zation for the Establishment of COD Limitations
IX
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TABLED
Number Page
28 Performance of Effluent Treatment Systems 174
Subcategory 6: Carpet Mills
29 Performance of Effluent Treatment Systems 177
Subcategory 7: Stock and Yarn Dyeing
30 Maximum Thirty Day Average 186
Effluent Limitations Guidelines for July 1, 1983
31 Maximum Thirty Day Average
Effluent Limitations Guidelines for New Sources 191
x
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FIGURES
Number Title gage
1 Subcategory 1: Wool Scouring 23
2 Subcategory 2: Wool Finishing 24
3 Subcategory 3: Greige Mills 30
4 Subcategory 4: Woven Fabric Finish 31
5 Subcategory 5: Knit Fabric Finishing 32
6 Subcategory 6: Carpet Mills 33
7 Subcategory 7: Stock and Yarn Dyeing and Finishing 34
8 COD Isotherms Using Virgin Carbon and Different m
Secondary Sewage Effluent
9 Schematic of an Activated Carbon System 112
Including Thermal Regeneration
10 Aerated Stabilization Basin Construction Cost 128
11 Engineering Costs 129
12 Clarifier Capital Cost 130
13 Aerated Stabilization Basin (Aeration Equipment Only) 131
14 Aerated Stabilization Basin Annual Operation and 132
Maintenance Labor
15 Aerated Stabilization Basin (Material and Supply 133
Costs, Annual) (Chemical Costs)
16 Aeration Equipment Annual Power Costs (Aerated 134
Stabilization Basin)
17 Clarifier, Annual Operation and Maintenance Labor 135
18 Clarifier (Material and Supply Costs, Annual) 135
(Major Chemical Costs)
XI
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FIGURES
Number Title Page
19 Typical Seasonal Variation for Biological 154
Treatment
20 Distribution of Water Use for Dry Processing 162
xi i
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SECTION I
CONCLUSIONS
The purpose of this report is to establish wastewater effluent
limitation guidelines for the textile manufacturing industry. A
conclusion of this study is that this industry comprises eight
subcategories:
1. Wool Scouring
2. Wool Finishing
3. Dry Processing
U. Woven Fabric Finishing
5. Knit Fabric Finishing
6. Carpet Mills
7. Stock and Yarn Dyeing and Finishing
8. Commission Finishing
The major criteria for the establishment of the subcategories are
the biochemical oxygen demand (BOD5J, chemical oxygen demand (COD),
and total suspended solids (TSS) in the plant waste water.
Subcategorization is required on the basis of the raw material used
and the production process employed. Evaluation of such factors as
age or size of facilities, location and climate and similarities in
available treatment and control measures substantiate this industry
subcategorization.
The wastes from all subcategories are amenable to biological
treatment processes and at least eighteen textile manufacturing
plants are able to achieve high levels of effluent reduction (BOD5
and total suspended solids) through secondary biological treatment
systems. These systems treat wastewaters from dyeing and finishing
broadwoven cotton and cotton synthetic blends, knits and stock and
yarn. It is estimated that the costs for all plants within the
industry to achieve the best practicable effluent reduction would
result in final product price increases ranging from 0.6 cents per
kilogram product (0.3 cents per pound product) to a high of 2.8
cents per kilogram (1.2 cents per pound). The average price
increase is 1.5 cents per kilogram (0.7 cents per pound). The
average price increase for new sources (biological treatment and
multi-media filtration) is 2.3 cents per kilogram (1.0 cents per
pound) . These potential price increases assume no credit for
treatment systems currently in place.
The cost of achieving the best available effluent limitations is
estimated to result in further final product price increases ranging
from 0.5 to 5.3 cents per kilogram (0.2 to 2.4 cents per pound)
product processed for all dry processing mills and for all small
plants in the other seven subcategories. Cost increases are
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expected to range from 0.4 to 1.8 cents per kilogram (0.2 to 0.9
cents per pound) for larger plants in the industry subcategories
(except dry processing mills). The average price increase is 3,8
cents per kilogram product (1.7 cents per pound product).
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SECTION II
RECOMMENDATIONS
The waste water effluent reduction limitations attainable through
the application of the best practicable control technology currently
available are based on the performances of exemplary secondary
biological systems treating textile manufacturing waste water. Best
practicable control technology currently available includes the
following treatment components: preliminary screening, primary
sedimentation (wool scouring only), latex coagulation (carpet mills
and dry processing only), and secondary biological treatment.
The waste water effluent reduction limitations attainable through
the application of the best available control technology
economically achievable are based on the best practicable control
technology plus advanced treatment including multi-media filtration
for dry processing operations and multi-media filtration and
chemical coagulation/clarification for the remaining seven
subcategories.
Recommended best practicable effluent limitations to be achieved by
July 1, 1977, are set forth in Table 1 and recommended best
available effluent limitations to be achieved by July 1, 1983, are
set forth in Table 2. These limitations are the average of daily
values for any period of thirty consecutive days. Maximum
limitations for any one day for BOD5, TSS, COD, oils and grease,
total chromium, phenol, sulfide and color should not exceed these
thirty day limitations by more than one hundred percent.
The waste water effluent reduction limitations for new sources are
those attainable through the application of the best practicable
control technology currently available plus multi-media filtration
or its equivalent for TSS control. These limitations are possible
because of the present availability of the treatment and control
technology to attain this level of effluent reduction.
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Table 1
Maximum Thirty Day Average
Effluent Limitations Guidelines (1)
for July 1, 1977
Subcategory
Wool Scouring(2,4)
Wool Finishing (4)
Dry Processing (3)
Woven Fabric
Finishing (4)
Knit Fabric
Finishing (4)
Carpet Mills
Stock and Yarn
Dyeing and Finishing (4)
(1) Expressed as
and Carpet Mil
BODS
5.3
11.2
0.7
3.3
2.5
3.9
3.4
kgllb) poll
kkg(lOOO Ibj
Is as kg(lb)
TSS
16.1
17.6
0.7
8.9
10.9
5.5
8.7
utant except
product
pollutant
COD
69.0
81.5
1.4
30-
60
30-
50
35.1-
45.
42.3
Wool
Total
Chromi urn
0.05
0.07
—
0.05
0.05
1 0.02
0.06
Scouring as kg(lb)
Phenol
0.05
0.07
—
0.05
0.05
0.02
0.06
pollutant
kkg (1000 Ib; raw
Sulfide
0.10
0.14
—
0.10
0.10
0.04
0.12
grease wool
kkg(1000 Ib) primary backed carpet
(2) Oil and Grease Limitation for Wool Scouring is 3.6 kg(lb)
kkg(1000 Ib) raw grease wool
(3) Fecal Coliform Limit for Dry Processing is 400 MPN per 100 ml.
(4) For those plants identified as Commission Finishers, an additional allocation of 100%
of the guidelines is to be allowed for the 30 day maximum levels.
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Table 2
Maximum Thirty Day Average
Effluent Limitations Guidelines (1)
for July 1, 1983
Subcategory
Wool Scouring(3,4) 2.4
Wool Finishing (4) 4.6
Dry Processing
Woven Fabric
Finishing (4)
Knit Fabric
Finishing (4)
Carpet Mills
Stock and Yarn
Dyeing and
Finishing (4)
(1) Expressed as kg (lb) pollutant except Wool Scouring as kg (lb) pollutant
kkg (1000 Ib) product kkg (1000 lb) raw grease wool
and Carpet Mills as kg Mb) pollutant
kkg (1000 lb) primary backed carpet
(2) Color in APHA units
(3) Oil and Grease limitations for Wool Scouring is 1.0 kg Mb)
kkg (1000 lb) raw grease wool
BOD5
2.4
4.6
n 9
U . L.
2.2
1.7
2.0
2.3
TSS
2.0
2.5
n ?
U . c.
1.5
1.7
1.0
1.9
COD
18.0
27.1
n d
w . H
10.0-
20.2
10.0-
16.7
11.7-
15.0
14.1
Total
Chromium
O.U5
0.07
0.05
0.05
0.02
0.06
Phenol
O.Ob
0.07
0.05
0.05
0.02
0.06
Sulfide
0.10
0.14
0.10
0.10
0.04
0.12
Fecal
Coll form
MPN
400 100ml
MPN
400 100ml
MPN
Ann i nClm!
tuu I uuin I
MEN
400 100ml
MPN
400 100ml
MPN
400 100ml
MPN
400 TOOml
Color (2)
600
600
300
300
225
300
(4) For those plants identified as Commission Finishers, an additional allocation of 100% of the guidelines
is to be allowed for the 30 day and maximum levels.
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SECTION III
INTRODUCTION
Purpose and Authority
Section 301(b) of the Act requires the achievement, by not later
than July 1, 1977, of effluent limitations for point sources, other
than publicly owned treatment works, which are based on the
application of the best practicable control technology currently
available as defined by the Administrator pursuant to Section 304(b)
of the Act. Section 301(b) also requires the achievement, by not
later than July 1, 1983, of effluent limitations for point sources,
other than publicly owned treatment works, which are based on the
application of the best available technology economically achievable
which will result in reasonable further progress toward the national
goal of eliminating the discharge of all pollutants, as determined
in accordance with regulations issued by the Administrator pursuant
to Section 304(b) to the Act. Section 306 of the Act requires the
achievement by new sources of a Federal standard of performance
providing for the control of the discharge of pollutants which
reflects the greatest degree of effluent reduction which the
Administrator determines to be achievable through the application of
the best available demonstrated control technology, processes,
operating methods, or other alternatives, including, where
practicable, a standard permitting no discharge of pollutants.
Section 304(b) of the Act requires the Administrator to publish
within one year of enactment of the Act, regulations providing
guidelines for effluent limitations setting forth the degree of
effluent reduction attainable through the application of the best
practicable control technology currently available and the degree of
effluent reduction attainable through the application of the best
control measures and practices achievable including treatment
techniques, process and procedure innovations, operation methods and
other alternatives. The regulations proposed herein set forth
effluent limitations guidelines pursuant to Section 304 (b) of the
Act for the textile manufacturing source category.
Section 306 of the Act requires the Administrator, within one year
after a category of sources is included in a list published pursuant
to Section 306(b) (1) (A) of the Act, to propose regulations
establishing Federal standards of performances for new sources
within such categories. The Administrator published in the Federal
Register of January 16, 1973 (38 F.R. 1624), a list of 27 source
categories. Publication of the list constituted announcement of the
Administrator's intention of establishing, under Section 306,
standards of performance applicable to new sources within the
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textile manufacturing source category, which was included within the
list published January 16, 1973.
Methodology
The effluent limitations guidelines and standards of performance
proposed herein were developed in the following manner. The textile
industry was first categorized for the purpose of determining
whether separate limitations and standards are appropriate for its
different segments. Considerations in the industry categorization
process included raw materials, the products, manufacturing process,
and raw waste characteristics.
The raw waste characteristics for each subcategory were identified
through analyses of: (1) the sources and volumes of water and waste
waters and (2) the constituents of all waste waters including toxic
or hazardous constituents and other constituents which result in
t'aste, odor or color. The constituents of waste waters that should
be subject to effluent limitations guidelines and standards of
performance were identified.
The full range of control and treatment technologies existing within
each subcategory were identified. This included an identification
of each distinct control and treatment technology, including both
in-plant and end-of-process technologies, which are existent or
capable of being designed for each subcategory. It also included an
identification, in terms of the amount of constituents and the
chemical, physical, and biological characteristics of pollutants, of
the effluent level resulting from the application of each of the
treatment and control technologies. The problems, limitations, and
reliability of each treatment and control technology and the
required implementation time were also identified. The non-water
quality environmental impact were also identified, e.g., the effects
of the application of such technologies upon other pollution
problems, including air, solid waste, noise, and radiation. The
energy requirements of each of the control and treatment
technologies were identified as well as the cost of the application
of such technologies.
The information, as outlined above, was then evaluated to determine
what levels of technology constituted the "best practicable control
technology currently available," "best available technology
economically achievable" and "best available demonstrated control
technology, processes, operating methods, or other alternatives."
In identifying such technologies, various factors were considered.
These included the total cost of application of technology in
relation to the effluent reduction benefits to be achieved from such
application, the age of equipment and facilities involved, the
process employed, the engineering aspects of the application of
various types of control techniques process changes, non-water
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quality environmental impact (including energy requirements), the
treatability of the wastes, and water use practices.
The data for the identification and analyses were derived from a
number of sources. These sources included EPA research information,
published literature, previous EPA technical guidance for textile
manufacture, various industry associations, qualified technical
consultation, and on-site visits and interviews at exemplary textile
manufacturing plants in the United States. All references used in
developing the guidelines for effluent limitations and standards of
performance for new sources reported herein are listed in Chapter
XIV.
General Description of the Industry
Since 1638, when the first commercial mill was erected at Raleigh,
Massachusetts, the U.S. textile industry has burgeoned to a point
where there are nearly 7100 plants in 47 states, employing about one
million people, and in 1972 selling goods valued at just under $28
billion. These plants range from highly integrated manufacturing
complexes that process basic raw materials into finished products,
to small non-integrated contract plants that process goods owned by
other producers.
According to the 1967 Census of Manufacturers, the textile industry,
SIC Code 22, contains ten major SIC classifications. In recent-
decades, the industry has been concentrating in the Southeast—
notably in the Cairolinas, Georgia and Alabama—and this trend is
continuing. Today 38 percent of the textile plants are in the
Southeast and 92 percent are on the eastern seaboard. The rest, as
shown in Table 3, are scattered throughout the country. Knitting
mills, with almost 2,700 plants listed, constitute the largest group
but there are also about 1,000 weaving mills of various types and
over 1,000 plants which process miscellaneous textile goods. Most
of the textile industry is contained within EPA Regions 1, 2, 3 and
4, with Region 4 accounting for a major proportion of the industry.
As shown below, almost 80 percent of the industry is located in the
southern and mid-atlantic states.
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Region Nmnber_of_Mil.ls % of Total
South 2656 38
Mid-Atlantic 2821 40
New England 978 14
North Central 321 4
West _301 _4
708C 100
Source: 1967 Census of Manufacturers
10
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Table 3
Number of Textile Plants by Geographic Areas:
1967
Textile
Mills
Products
NORTHEAST REGION
New- England Div.
Maine
New Hampshire
Vermont
Massachusetts
Rhode Island
Connecticut
Mid. Atlantic Div.
New York
New Jersey
Pennsylvania
NO. CENTRAL REGION
E. Mo. Central Div
Ohio
Indiana
Illinois
Michigan
Wisconsin
W. No. Central Div
Minnesota
Iowa
Missouri
22
7,080
3,799
978
56
79
14
400
293
136
2,821
1,521
558
742
321
. 251
74
13
76
30
58
70
24
7
34
Weaving
Mills
Cotton
221
393
78
21
4
1
-
-
4
4
57
17
25
15
-
_
-
-
-
-
-
-
-
-
-
Weaving
Mills
Synthetic
222
396
196
64
7
9
-
19
23
6
132
33
37
62
7
_
-
-
-
-
-
3
-
-
2
Weaving &
Finishing
Mills-Wool
223
310
216
127
18
16
7
41
36
9
89
39
10
40
22
12
5
-
3
-
2
10
6
-
3
Narrow
Fabric
Mills
224
384
258
121
-
15
-
37
51
15
137
50
31
56
14
9
3
-
3
-
-
5
-
-
-
Knitting
Mills
225
2,698
1,616
113
3
15
-
49
15
28
1,503
964
192
347
76
61
19
1
14
2
25
15
8
-
5
Textile
Finishing
Exc. Wool
226
641
423
98
-
4
-
45
31
18
325
144
131
50
29
24
7
-
13
1
3
-
-
-
-
Floor
Covering
Mills
227
385
83
35
3
-
-
19
10
1
48
16
3
29
13
12
-
2
-
-
3
-
-
-
-
Yarn &
Thread
Mills
228
768
304
128
11
11
-
53
34
16
176
70
28
78
15
15
5
-
4
-
5
-
-
-
-
Misc .
Textile
Goods
229
1,105
625
271
7
6
-
129
89
39
354
188
101
65
141
111
28
10
35
21
17
t,
30
8
-
18
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Table 3 (Con't)
Textile Weaving Weaving Weaving & Narrow Textile Floor Yarn & Misc.
Mills Mills Mills Finishing Fabric Knitting Finishing Covering Thread Textile
Products Cotton Synthetic Mills-Wool Mills Mills Exc.__.Wool Mills Mills Goods
22 221 222 " 223 224 225 " 226 "227 ~228 "" 229
SOUTH REGION
So, Atlantic Div.
Delaware
Maryland
Virginia
West Virginia
North Carolina
South Carolina
Georgia
Florida
E. So. Central Div,
Kentucky
Tennessee
Alabama
Mississippi
W. So. Central Div
Arkansas
Louisiana
Oklahoma
Texas
WEST REGION
Mountain Division
Utah
Pacific Division
Washington
Oregon
California
2,656
2,214
13
30
109
5
1,260
359
407
31
344
27
149
141
27
98
16
10
6
66
304
18
5
286
20
20
245
307
254
-
-
6
-
67
112
67
-
34
-
4
29
1
19
3
-
-
15
-
_
-
_
-
-
-
190
178
-
-
22
-
77
57
21
-
10
-
3
6
-
2
-
-
-
2
-
_
-
_
-
-
-
52
43
-
3
10
1
6
11
11
-
7
-
2
2
-
2
-
-
-
2
20
_
-
18
1
8
9
101
83
-
6
9
1
40
19
6
-
18
-
6
7
2
_
-
-
-
-
11
_
-
11
-
-
10
910
770
8
5
30
3
630
38
44
12
130
10
76
29
15
10
5
-
-
4
96
5
2
91
6
5
80
170
145
2
5
9
-
77
31
16
-
19
-
11
6
-
6
1
-
1
-
19
_
-
17
-
-
16
231
199
-
-
3
-
35
19
142
-
24
-
13
7
1
8
3
-
1
-
58
_
-
57
-
-
56
443
387
-
5
8
-
262
41
70
1
51
2
13
35
-
_
-
-
-
-
6
_
-
5
-
-
5
252
155
3
-
12
-
65
31
30
-
51
A
21
20
6
46
4
9
-
31
87
-
-
81
-
-
66
-------
The industry's basic raw materials are wool, cotton, and man-made
fibers. Of the roughly 5.0 billion kilograms (11 billion pounds) of
raw materials consumed by the industry in 1972, wool (computed on a
clean basis) accounted for about 0.09 billion kilograms (0.2 billion
pounds), cotton for 1.8 billion kilograms (4 billion pounds) and
man-made fibers for 3.2 billion kilograms (7 billion pounds).
Among the man-made fibers, the most important are rayon, acetate,
nylon, acrylic, polyester, polypropylene, and glass fiber.
The natural fibers are supplied in staple form, (staple being short
fibers). The man-made fibers are supplied as either staple or
continuous filament. In either case the fiber is spun into yarn,
which is simply a number of filaments twisted together. The yarn is
woven or knit into a fabric, and the fabric then dyed and treated to
impart such characteristics as shrink resistance, crease resistance,
etc. The finished fabric is delivered—directly or through
converters, jobbers, and wholesalers-to the manufacturer of textile
products.
The many woven fabrics are produced by variations in the weaving
pattern. Plain, or tafeta, weaves give such fabrics as broadcloth,
calico, cheesecloth, muslin, seersucker, flannel and tweed. Twill
weaves are represented by serge, herringbone, jersey, gabardine, and
ticking. Because of their superior strength, twill fabrics are used
for work clothes and men's suits. Satin weaves are smooth but weak;
the best known are crepe satin, sateen, and damask. Dobby and
Jacquard weaves are used to produce patterned fabrics. Dobby weaves
are used in men's shirting and women's dress fabrics. Jacquard
weaves are used extensively for upholstery and drapery materials.
, Finally, there are the pile weaves, which include velvets, plushes,
corduroys and turkish toweling.
In transforming a fiber into one of these woven fabrics, two types
of processes are used: wet and dry. The SIC code breakdown is not
particularly useful for evaluating the waste effluent problems of
the textile industry. These codes are grouped primarily by the
process used--e.g., weaving or knitting--^whereas the waste effluent
problems stem from all the wet processes which are used to desize,
wash, dye and finish the textile fabric. The wet processes of
interest include: scouring, desizing, mercerizing, bleaching, dyeing
and finishing. Dry processes include: spinning, weaving, knitting,
bonding and laminating. Although SIC Code 226 identifies textile
finishing, Code 221 identifies weaving mills which may also be
integrated mills that have a finishing operation or may be greige
goods mills that have only dry processing. Knitting mills fall into
a similar category; many of the mills identified as knitting mills,
in fact, process dyed yarns and, therefore, essentially carry out
dry operations.
13
-------
There is no exact figure for the number of wet processing plants or
the total water use by the industry, but the Census of Manufacturers
gave for 1968 under Textile Mill Products a total of 684 wet plants
which consume 412 billion liters (109 billion gallons) of process
water per year. (This includes sanitary and cooling water, etc.) A
more recent estimate, by the American Textile Manufacturers*
Institute in 1970, found 346 plants using 394 billion liters (104
billion gallons) per year, estimated to be 83 percent of the total
industry use.
Table 4 gives details of the process water used and discharged
divided as far as possible according to the EPA subcategories. The
largest water users are undoubtedly the finishing plants, v/ith a
total of 269 billion liters (71 billion gallons) per year, averaging
7.3 million cubic meters per day (19 million gallons per day). The
next highest category is the wool finishing operations, with 47.3
billion liters (12.5 billion gallons) per year averaging 27,000
cubic meters per day (0.7 million gallons per day) but consisting of
a much smaller segment of the textile industry.
A summary of this data is presented in Table 5, which shows that 110
billion liters (29 billion gallons) per year or 26.6 percent of the
water was discharged to municipal sewers and 73.2 percent or 303
billion liters (80 billion gallons) per year to surface water. The
73.2 percent also divides into 24.2 percent that received no
treatment, 21 percent that received primary treatment and 28.2
percent that received secondary treatment before discharge. Since
1968 many more treatment plants have been built and from a
consideration of RAPP data and the recent survey by the ATMI, we
estimate that about 35 percent of the water used is now discharged
to municipal sewers, 15 percent receives no treatment, 5 percent
receives primary treatment and 45 percent receives secondary
treatment. Undoubtedly, the smaller mills or those using the least
amounts of water have found it more economical to use municipal
treatment instead of constructing their own facilities.
14
-------
Value of
Shipments
Table 4
Water Use by the Textile Industry
Average
No. of Process Water Water
Plants Water Used use/plant Sewer
Discharged Treated Before Discharge
Surface Total Ponds
SIC
Code
22
2297
2231
+2283
2211
+2221
+2241
+ 226
225
227
228
(-2283)
ADL
Category
Total
1
2
4
5
6
7
(Million 106 cu m/yr
dollars) (BG/yr)
413.
9,235.5 684 (109.0)
2.6
49.5 9 (0.7)
47.3
758.2 67 (12.5)
269.
4,787.3 348 (71.1)
32.
1,119.7 100 (8.4)
30.
1,067.6 50 (7.8)
21.
660.3 60 (5.6)
cu m/d
(MGD)
2100.
(0.56)
1100.
(0.28)
2600
(0.68)
2800
(0.73)
1100.
(0.30)
2100.
(0.56)
1200.
(0.33)
106 cu m/yr
(BG/yr)
192.
(50.6)
.38
(0.1)
15.
(3.9)
99.5
(26.3)
28.
(7.4)
23.
(6.1)
16.
(4.2)
10° cu rn/yr
(BG/yr)
306.
(80.9)
3.4
(0.9)
42.4
(11.2)
213.
(56.4)
11.
(2.9)
11.
(2.8)
16.
(4.3)
106 cu m/yr
(BG/yr)
203
(53.7)
2.3
(0.6)
26.
(6.9)
137.
(36.3)
8.7
(2.3)
11.
(2,8)
15.
(3.9)
106 cu m/yr
(BG/yr)
117.
(30.8)
(-)
15.
(3.9)
74.9
(19.8)
2.3
(0.6)
6.4
(1.7)
14.
(3.8)
Source: Department of Commerce -- 1967 Census of Manufacturers
-------
cr\
Table 5
Water Discharged by the Textile Industry
1968
To Municipal Sewer
To Surface Water:
1. No Treatment
2. Primary Treatment
3. Secondary Treatment
TOTAL PROCESS WATER
1972
Amount Percent Amount Percent
106 cu m/yr of 106 cu m/yr of
BG/yr Total BG/yr^ Total
110.
(29.)
99.5
(26.3)
86.7
(22.9)
116.
(30.8)
413.
(109.)
26.6
24.2
21.0
28.2
100.0
166. 35.
(44.)
71.
(19.) 15.
24. 5.
(6.)
213. 45.
(56.)
473. 100.0
(125.)
Sources: Department of Commerce 1967 Census of Manufacturers
Refuse Act Permit Program Data
American Textile Manufacturers Institute
Arthur D. Little, Inc. Estimates
-------
Profile of Manufacturing Processes
As mentioned above the industry's basic raw materials are wool,
cotton and synthetic fibers. The fiber and fabric finishing
operations are described below for each of these three materials.
Finally, these operations are related to the selected
subcategorization through brief process descriptions of each
subcategory. The rationale for subcategorization along with
detailed descriptions of the seven segments is given in Section IV.
Wool Fiber and Fabric Finishing Operations
Wool fiber consumption is smaller than either cotton or synthetic
fiber and the trend seems to be a decreased demand in the future on
a percentage basis. The operations required to produce a finished
piece of woolen fabric are described below - either knitting or
weaving can be done at a given mill. The first treatment given to
raw wool after it leaves the sheep's back is usually that of
scouring or washing. Scouring frees the wool from considerable
quantities of natural grease, soluble salts (perspiration or suint),
sand and dirt which are always present. There are two methods of
wool scouring - detergent scouring and solvent scouring. In the
United States the detergent scouring process is used almost
exclusively. The process is carried out in a series of four long
narrow bowls. The first two bowls have a capacity of between 1500
and 2000 gallons and the normal procedure is to employ sodium
carbonate and a little soap or non-ionic detergents of the ethylene
oxide condensate class. In the third bowl a small quantity of non-
ionic detergent is used and the last bowl employs water only. The
pH of the scouring bath varies between pH 9 and 10.5 depending upon
the type of wool. The temperature varies from 125 - 130°F in the
first bowl to 110 - 115°F in the last bowl. This process consumes a
volume of 8,000 to 12,000 gallons of water per 1000 Ibs. of wool
fiber. Wool scouring produces one of the strongest wastes in terms:
of BOD. This process contributes 55 to 75% of the total BOD load in
wool finishing.
The next wet processing step is carbonizing and the object is to
remove cellulosic impurities existing either as vegetable burrs and
seeds or as vegetable fibers from wool materials (in the form of
loose wool or woven goods).
The carbonizing treatment is based on the degradation of cellulose
to hydro-cellulose when acted upon by mineral acids - generally
sulfuric acid - at high temperatures and consists essentially of
impregnating the contaminated materials with a dilute solution of
acid; drying, baking, and subjecting to mechanical action whereby
the degraded cellulose is removed as dust.
17
-------
Loose wool intended for manufacture on the woolen system is
carbonized in this form if the content of vegetable impurity is high
or if it is to be used in the production of fancy woolens. Wool
containing less vegetable contamination and destined for manufacture
into piece dyed styles is carbonized in the piece form.
Following carbonizing, the wool stocks or fabrics are thoroughly
rinsed and neutralized with sodium carbonate. After this
neutralization bath the fabric is rinsed again. Since sulfuric acid
and sodium carbonate have little or no BOD this process contributes
less than 1* of the total BOD.
Wool is dyed in either the loose state, as yarn or as piece goods.
The classes of dyes are *• acid dyes, mordant dyes and metallized
dyes. Dye formulations will vary depending on the use of the wool.
Acid dyes are generally used for women's wear with mordant and
metallized dyes used for men's wear. In dyeing of wool the dye
bath temperature will vary from 140°F to 205°F. The pH will vary,
depending upon the dyes used, from pH 6.5 to highly acid pH 1.5.
The volume of waste water generated by dyeing is large and highly-
colored. The BOD load is contributed by the process chemicals used,
and the contribution of wool dyeing to the mills total BOD load is 1
to 5 percent.
Loose wool is oiled after drying to facilitate the spinning
operation. The oiling step does not contribute directly to the
waste water stream. The process chemicals are washed out of the
fabric during the fulling step or scouring prior to dyeing or
bleaching. Woolen fabrics are generally fulled prior to dyeing.
Shrinkage is induced and controlled according to the type of finish
required.
There are two common fulling methods, alkali and acid fulling. In
the former case soap or detergent, sodium carbonate, and
sequestering agents are used. In the acid fulling, the fabric is
impregnated with an aqueous solution of sulfuric acid (from
carbonizing). In either case the bath temperature is 100 - 115°F at
pH 4.0 to 8.0. Following this operation the goods are washed to
remove the fulling chemicals. It is estimated that from 10 to 25%
of the fulled cloth's weight is composed of process chemicals that
will be washed out in this process and wasted. Due to this large
amount of waste, wool washing after fulling is the second largest
source of BOD, contributing 20 - 30% of the total. The usual
procedure in the process is to subject the fulled cloth to two
soapings, two warm washes and one cold rinse. Usually a 2% solution
of soap or detergent is used in the soaping. The warm water rinsing
is done at 1CO°F. This process consumes from 15,000 - 25,000
gallons of water for each 1000 Ibs. of wool fabric. Analyses show
that wool, once thoroughly washed, will produce little or no BOD of
itself on being rewashed.
18
-------
In the processing of wool fibers, five sources of pollution load
exist - scouring, dyeing and/or whitening or bleaching, fulling,
carbonizing and chemical finishing. Figures 1 and 2 represent the
basic operations that take place in woolen fabric manufacturing.
Cotton Fiber and Fabric Finishing Operations
The consumption of cotton fibers by textile mills in the United
'States exceeds that of any other single fiber; however, the total
synthetic fiber poundage consumed by the textile industry is greater
than that of cotton. The operations required to produce a piece of
finished cotton fabric are described below.
Slashing is the first process in which liquid treatment is involved.
In this process, the warp yarns are coated with "sizing" in order to
give them tensile strength to withstand the pressures exerted on
them during the weaving operation. Such substances as starch,
starch substitutes, polyvinyl alcohol, carboxy methyl cellulose,
gelatin glue and gums have been used as size agents. The source of
pollution in this process results from the cleaning of slasher
boxes, rolls, and make up kettles. The volume is therefore usually
low; however, the BOD can be quite high, especially if starch is
used.
The operation of desizing removes the substance applied to the yarns
in the slashing operation, by hydrolyzing the size into a soluble
form. There are two methods of desizing - acid desizing and enzyme
desizing. In acid desizing, the fabric is soaked in a solution of
sulphuric acid, at room temperature, for 4 to 12 hours, and then
washed out. In enzyme desizing, complex organic compounds produced
from natural products or malt extracts are used to solubilize the
size. The bath is maintained at a temperature of 130° - 180°F. and
a pH of 6-7.7, for a period of 4-8 hours. Due to the unstable
nature of these organic compounds, the whole bath must be discarded
after each batch. After the size has been solubilized, the fabric
is rinsed clean. Desizing contributes the largest BOD of all cotton
finishing processes - about 45 percent.
Scouring follows desizing. In this process, the cotton wax and
other non-cellulosic components of the cotton are removed by hot
alkaline detergents or soap solutions. In most modern plants,
scouring is done in conjunction with desizing rather than as a
separate operation. Caustic soda and soda ash along with soaps and
synthetic detergents and inorganic reagents are used to remove the
non-cellulose impurities. The bath is characterized by a pH of 10
to 13 and temperatures of up to 212°F. Although the strength of
alkali in the beginning of the operation is between 1 percent and 5
percent, the waste liquor will have a 0.3 percent alkaline
concentration, the rest being taken out of solution by the cotton
fibers. In a few mills, the scouring process is a batch operation
19
-------
requiring the fabric to remain in the kier for a period of from 2 -
12 hours. Scouring is the second largest BOD contributing process
in the finishing of cotton textiles - about 31 percent. Following
the "boil-off," the goods are rinsed clear with hot and cold water
to remove residual alkali.
Bleaching, the next process, removes the natural yellowish coloring
of the cotton fiber and renders it white. The two bleaches most
commonly used for cotton are sodium hypochlorite and hydrogen'
peroxide. In hypochlorite bleaching the fabric, after scouring, is
impregnated with an alkaline solution of hypochlorite and allowed to
stand at room temperature for 4 to 12 hours. It is then washed,
saturated with a weak solution of hydrochloric or sulfuric acid for
neutralization and then again washed.
About 80% of the cotton containing fabrics which are bleached white
are done on continuous ranges using hydrogen peroxide. The fabric,
after desizing, is impregnated with a 2-3% solution of caustic soda
and stored in a "J" box at 200°F for 1 hour. This operation
replaces the kier scouring of the batch method. After the caustic
scour, the fabrics are washed and then impregnated with a 2-3%
solution of hydrogen peroxide and again go into a storage "J" for 1
hour at 200°F. After this the fabrics are washed. All of the above
are syncronized so as to give a continuous output of 50 to 200 yards
per minute depending on the weight of the fabric and size of the
equipment.
The mercerization process was originally developed to give increased
luster to cotton fabrics. Today it is still used for that purpose,
but more importantly to impart increased dye affinity and tensile
strength to the fabric. It is estimated that only 30 percent of all
cotton fabrics are now mercerized, and with the increasing use of
cotton-polyester blends, less will probably be done in the future.
The process uses a 15 to 2*+ percent solution of sodium hydroxide at
room temperature for 1/2 to 3 minutes. The fabric is then rinsed in
an acid wash to neutralize the fabric, washed in water and then
dried. The effluent from this process is alkaline and high in
dissolved solids, but low in BOD.
After mercerizing, the goods are sent to the dye house or color
shop. In the dye house they are dyed either in small volumes in
batch process machines, or on continuously dyeing ranges in large
volumes. There are five important classes of dyes used on cotton
fabrics: vat, developed, sulphur, direct, and fiber reactive.
The dyeing process is carried out in an aqueous bath with pH
variations, cotton fabrics are printed with primarily three classes
of colors: pigments, vats, and fiber reactives. The most important
methods of printing are roller printing and rotary and flat bed
screen printing. The color in the former method of printing is
20
-------
delivered to the fabric by way of a print paste from an engraved
roll. The latter method requires the print paste to be pushed
through a perforated screen to the fabric. The print paste contains
color, thickener, Varsol (pigment systems only), hygroscopic
substances, resins (pigment system only), and water. With fiber
reactive dyes, the pH of the print paste is adjusted to 8.5. The pH
of the print paste for vat dye is neutral, but the print is treated
with caustic soda and hydrosulfite prior to flash aging.
The pollutional load from the color shop comes mainly from the wash-
down rinses used to clean the equipment in the shop and the cloth
rinsings. The pollutional load is rather low in both volume and
BOD. When a mill does both printing and dyeing, the BOD
contribution of the combined processes is 17 percent, and the total
BOD load comes from the process chemicals used.
Synthetic Fiber and Fabric Finishing Operations
In this category of textile fibers there are two broad
classifications: cellulosic and non-*cellulosic fibers. The two
major cellulosic fibers are rayon and cellulose acetate. The major
non-cellulosic fibers are nylon, polyester, acrylics and
modacrylics. There are other fibers in both classes, but at present
they are not consumed in as large a volume as the six fibers
mentioned above. The largest volume of synthetic fibers consumed by
textile mills comes from the non-cellulosic fibers; and the trend is
toward an even greater demand in the future, particularly for
polyester fibers. Synthetic fibers can be converted into fabrics in
one of two ways. Continuous filament yarns can be used to
manufacture 100 percent synthetic fabrics, or staple yarns can be
used to produce fabrics that are blends of man-made fibers or man-
made and natural fibers. Blended fabrics are processed according to
the natural fiber component of the yarn.
The first process in which synthetic fibers would be subject to an
aqueous treatment is stock dyeing, unless the fabric is to be piece
dyed, printed, or used in white. When stock dyeing is used, the
liquid waste discharge will vary from about 8 to 15 times the weight
of the fibers dyed.
Due to the low moisture regain of the synthetics, static electricity
is a problem during processing. To minimize this problem, anti-
static materials are applied to the yarns, which also serve as
lubricants and sizing compounds. These compounds commonly used are:
polyvinyl alcohol, styrene-base resins, polyalkylene glycols,
gelatin, polyacrylic acid, and polyvinyl acetate. These compounds
become a source of water pollution when they are removed from the
fabrics during scouring. Since the manufacture of synthetic fibers
can be well controlled, chemical impurities are relatively absent in
these fibers; therefore, only light scouring and little or no
21
-------
bleaching are required prior to dyeing; and if synthetics are
bleached, the process is not normally a source of organic or
suspended solids pollution. The process may generate dissolved
solids when chlorine bleaches are used.
Process Description by Subcategory
Subcategory 1_ - Wool Scouringi A generalized flow diagram of the
wool scouring process is shown in Figure 1. Scouring consists of
sorting the fleece and feeding it to a hopper. The wool then is
carried through a series of scouring bowls where scour liquor flows
countercurrent to it. Detergent is added in the third or fourth
bowls to emulsify the greases and oils. The scoured wool is then
dried. In mills where the cleaned wool is converted into wool top,
the wool is combed and gilled. The products are short fibers (used
for wool yarn) and long fibers (used for worsted yarn) .
Subcategory 2 - Wool Finishing: The wool finishing process is
depicted in Figure 2. The three distinct finishing processes are
shown as stock, yarn and fabric finishing. Because the pollution
generated by the fabric finishing operation is similar to that
generated by the other two, fabric finishing is included in this
discussion. If the greige goods are 100 percent wool, they are
first cleaned of vegetable matter by carbonizing and then cleaned of
spinning oils and any weaving sizes by a light scour. The 100
percent woolens are then dimensionally stabilized, principally by
"fulling," or mechanical working of the wet fabric in the presence
of detergents, to produce a controlled shrinkage or "felting."
Worsteds and most wool^synthetic blends are not fulled. Worsteds
are hard, tightly-woven and dimensionally stable as received at the
finishing plant; woolens are loosely-woven, soft and often are
firmed up by fulling.
The fabric is then dyed in batches in vessels called becks, washed
in the same vessels, and taken to dry finishing operations. The
only dry finishing operation of concern to water pollution is
mothproofing.
22
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Short
Fibers
For Wool
Yarn
Source: "Chemical/Physical and Biological Treatment of Wool Processing Wastes," by Hatch, et al, 28th Annual Purdue Industrial
Waste Conference, West Lafayette, Indiana, 1 May 1973.
Figure 1 Subcategory 1: Wool Scouring
-------
f
>
/
\
1
1
/I
Bleach an
Rinse
rl
'
Light
Scour
i
t
i
\
riii
LW J fLW
Top Dyeing
I Yarn Dyeing / ( PV,or
i ' \ CMC
Special
Finishing
e.g.
Mothproofing
Mechanical
Finishing
— Shear
- Press
= Solid Wastes
Figure 2 Subcategory 2: Wool Finishing
-------
Subcategory 3 - Dry grocessing^ Dry processing textile- mills include
greige mills (yarn manufacture, yarn texturizing, and unfinished
fabric manufacture), coated fabrics, laminated fabrics, tire cord
fabrics and felts and carpet tufting and carpet backing. The
principal source of effluent from such products and processes is the
washing and cleaning of equipment.
Any mill making unfinished fabric is known as a greige mill.
Weaving textile yarns into a fabric requires application of size to
the warp yarns in order to resist the abrasive effects of the
filling yarns as these are positioned by the shuttle action of the
'- loom. Greige mills apply the size and complete the weaving, but do
no materials finishing. Many operate as completely independent
facilities. Figure 3 shows operations generally performed at one
type of greige mill.
Weaving is a dry operation, but is normally done in buildings
maintained at high humidity. Under these conditions, the size film
is flexible, and yarn breaks on the loom are minimized. Yarns sized
with polyvinyl alcohol may be woven at a somewhat lower humidity
than yarns sized with starch. Cooling and humidifying water used in
a greige mill represents a substantial portion of the total water
usage. Industrial wastes from knit greige goods are nil. If any
wastes are generated they are from the knitting oils, however, these
would only enter the waste stream through spills, wash up or
possibly from the washing of the final product.
Polyvinyl chloride (PVC) coated fabrics dominate coated fabric
production included under SIC code 22. Rubberized, or rubber
coated, fabrics are specifically excluded from this code and are
- assigned to SIC code 3069. It is estimated that PVC coatings
account for 70 percent or more of total coated fabric production.
These coatings are applied as 100 percent "active solids" systems
,, either as plastisols (dispersion of polymer particles in liquid
plasticizer) or as melts (flexible grade polymer plus plasticizer).
The plastisols are generally coated by knife over roll coaters and
the melts are applied by calenders. A minor portion, estimated at
10 percent or less, of coated fabrics is coated with polymer latices
(PVC or acrylic). In this case some dilute aqueous waste is
generated from equipment wash-ups. Plastisol coating and
calendering of PVC coatings do not involve process water use.
Therefore, these plants are dry operations.
Felts are composed of fur, hair, wool and synthetic fibers in
various combinations. Synthetics are vastly predominant today.
Felt is a nonwoven material formed by physically interlocking fibers
by a combination of mechanical work, chemical action, moisture, and
heat. After felting, the felt is rinsed. If dyeing is performed,
it is done in the fiber form before felting. Often the felts are
25
-------
finished with a resin of the resorcinol/formaldehyde or acrylic
type.
Nonwoven webs made by so-called dry processes (carded webs, air-laid
webs, etc.) comprise the largest segment of the nonwoven industry.
While the webs are formed by a dry process, binders are usually
applied in the form of latex by dip, gravure roll, or spray
application. Acrylic polymer type latices account for about 80
percent of total binders used. The binder formulations are
conserved for use on a day-to-day basis. However, some dilute
aqueous wastes are generated by equipment wash-ups.
Tire cord fabric plants prepare the cord fabrics used in the
production of tires. These plants purchase yarns and twist and
weave the yarns into a loose fabric structure. The fabric is then
dipped in a latex based bath and dried in what is referred to as a
Z-calendering operation. This treatment serves to prime the fabric
to provide adhesion to the rubber during vulcanization of the tire.
The only process waste generated in these plants originates from
occasional wash-ups of equipment. Our assessment of available data
from a number of these plants indicates that waste loads are
extremely small.
For carpet backing, a continuous applicator applies a foamed latex
layer to the carpet's underside. In double-backed carpet, a layer
of unfoamed latex is applied in the same manner, and a final fabric
backing is pressed on, being cemented in place by the latex. In
either case, a liquid latex waste is generated. Some of the latex
becomes hardened, so a mixture of solid and liquid latex results.
Some of this material is collected by shovelling it into a barrel
for land-fill disposal. The rest is washed off by hosing and
removed by coagulation.
Subcategory 4. - Woven Fabric Finishing: Wet processes which are
used in finishing woven greige fabric may be divided into two
groups: those used to remove impurities, clean or modify the cloth;
and those in which a chemical is added to the cloth.
The first of these groups includes desizing, scouring, bleaching,
mercerizing, carbonizing and fulling. Only cotton and cotton blends
are mercerized. The last two of these processes are used only on
wool and wool blends.
The second group of processes includes dyeing, printing, resin
treatment, water proofing, flame proofing, soil repellency and a few
special finishes whose use represents a very small proportion of the
total.
Certain fabrics, including denims and some drapery goods, are "loom
finished." In production of these goods, the warp yarns are dyed,
26
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woven to a fabric, and the fabric finished with a permanent size.
For these fabrics, the first group of processes listed above
(cleaning and preparing the cloth) is avoided entirely. For this
reason, mills producing this group of fabrics may be a subcategory,
although we have not treated it as such. The degree of finishing
necessary to provide fabric ready for sale depends significantly on
the fiber(s) being processed. The natural fibers (cotton and wool)
contain substantial impurities, even after they have been woven as
greige goods, and require special treatments to convert them to the
completely white, uniformly absorbent form that is essential for
dyeing, resin treatment, etc. Synthetic fibers contain only those
impurities that were necessary for manufacture of the fiber and
spinning to obtain yarn.
The different operations listed above have been described in the
literature. A flow sheet for woven fabric finishing is given in
Figure 4.
Subcatecjory. 5 _ Knit Fabric Finishing: The wet processing
operations performed in knit fabric finishing are shown
schematically in Figure 5. This is necessarily a generalized
flowsheet; the specific operations employed will vary from plant to
plant. In general, the yarns are purchased in the undyed state,
with a knitting oil finish to provide lubrication for the knitting
operation. The amount of finish on the yarn ranges from 1 to 7
percent depending on the type of yarn and fiber. This is a
significant difference from weaving yarns which are sized with
starch or other polymeric materials. After the yarn has been
knitted into fabric, the fabric may be processed by one or more of
the alternative routes indicated in Figure 5^ The wet process
operations employed in a plant depend on the nature of the goods
involved and the end product requirements.
§Jife£S^S32£Y §. ~~ £S£E£i Mills^ Carpets are yarn dyed, piece dyed,
and printed. When yarn dyed carpets are made, the yarn is often
dyed in another mill and brought to the carpet mill. The relative
quantities of carpets which are produced from yarn-dyed fiber, or
colored by beck dyeing, continuous dyeing or printing may vary
widely. The amount and degree of latexing may also vary.
The dyed or greige yarn is tufted onto a polypropylene or jute woven
backing in a dry operation (Figure 6). Following this, the tufted
carpet can be either printed or dyed. If printed, a semi-continuous
screen printing operation is performed, followed by a wash and rinse
step in the same machine. If dyed, the most common method is beck
dyeing, in a manner quite similar to that described in previous
categories for piece goods. The industry claims a higher liquor-to-
fabric ratio, however, because of the difficulty in making the
carpet sink and become thoroughly wetted. Many, small air bubbles
become entrapped in the tufts and excess water must be added to
27
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weigh down the carpet. The continuous dyeing process consists of
the application of dye followed by a steam fixation treatment in a
mildly acidic atmosphere. Washing follows to remove residual dye,
acid, thickeners, and any materials which had been previously
applied to the yarn to facilitate tufting. Substantial amounts of
dyes and chemicals may be in the effluent from both the steamer and
the wash boxes. After it is dyed the carpet is dried in a tunnel
drier. The carpet is then ready for application of either a single
or a double backing.
jfory 2 ~ §£o£l$ and Yarn Dyeing and Finishing: In this
sufccategory, crude yarn is obtained from a spinning facility. The
yarn may be natural, synthetic, or blended. Wet processes used by
yarn mills include scouring, bleaching, mercerizing, dyeing, and
finishing (Figure 7).
Several techniques are available for processing raw yarn into the
finished product. The most common process is probably package
dyeing, but other processes, such as skein or space dyeing, are
widely used. In the former process, yarn wound on perforated tubes
is placed in a large vessel, which is sealed. The dye solution, at
an appropriate temperature, is circulated through the yarn and dye
fixation or exhaustion is carried out at an appropriate temperature.
The dyed yarn is worked, rinsed and dried. In space dyeing, yarn is
knit and the fabric is piece dyed, washed, rinsed and dried. The
fabric is then unravelled and the yarn is wound on cones. In skein
drying hanks of yarn are placed in a dyeing vessel and the dye bath
circulated through the hanks. Following rinsing, the yarn is
rewound on hanks for future use.
Subcategory 8 - Commission Finishing
The processing operations performed in commission finishing plants
may be any sequence of operations discussed for the above
subcategories and shown schematically in Figures 1-7.
Commission finishers process material upon demand according to their
customer's specification. Hence, they have little or no control
over the scheduling and flow of material through the plants.
Because they must respond to a wide range of customer needs, they
must have the capability to provide a broad variety of processes.
They characteristically carry out special or "problem-type"
operations that fall outside the capability of conventional
operations. They typically process short runs of material which
often require batch processing equipment as well as continuous
processes. By its nature, the commission house is unable to
carefully plan and schedule its operations due to dependence on
outside sources for quantity, quality and rate of supply. The
processes involved may be extremely varied, and a single plant may
carry out dyeing and finishing of textiles in all forms, from yarn
28
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and stock to printed and finishing fabric. Because of the
flexibility required, the equipment is typically not automated nor
as efficient as those found in larger, integrated dyeing and
finishing plants.
29
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OJ
o
Cotton-
Polyester
Woven
Fabrics
To Yarn Dyeing and
Finishing (Cat. 7)
To Woven Fabric
Finishing (Cat. 4)
To Knit Fabric
Finishing (Cat. 5)
To Woven Fabric
Finishing (Cat. 4)
To Yarn Dyeing and
Finishing (Cat. 7)
= Sol id Waste
LW I = Liquid Waste
Figure 3 Subcategory 3: Greige Mills
-------
Finishing
Agent, e.g.
Starch,
Resin
Figure 4 Subcategory 4: Woven Fabric Finish
-------
U)
NJ
LW ) = Liquid Wastes
Figure 5 Subcategory 5: Knit Fabric Finishing
-------
Predyed Yarn
to
oo
= Solid Waste
Figure 6 Subcategory 6: Carpet Mills
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Cotton or
Cotton-Blend
Yarn or
Stock
Dye
Mercerize
i
Bleaching
i
^
t
i
Dy
J
1
^
Liquid Wastes
Figure 7 Subcategory 7: Stock and Yarn Dyeing and Finishing
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SECTION IV
INDUSTRY CATEGORIZATION
PREVIOUS APPROACHES
In deriving this industry categorization system, existing
categorizations and other previous attempts at categorization have
been considered. The principal systems investigated were:
a. SIC codes. These codes do not lend themselves to a
classification of the industry with respect to
characterization of the pollution loads generated. For
example, Subcategory 3, dry processing, includes more
than 10 SIC categories.
b. The method advanced by the report, "A Simplification of
Textile Waste Survey and Treatment" by Masselli,
Masselli and Burford. This approach consists of
synthesizing the raw waste load from a textile mill by
additive contributions of the chemicals used. Tables of
BOD values for many chemicals are given in the report.
This method was judged too difficult to be implemented
by persons not versed in Textile Chemistry and not
knowledgeable about the chemicals used.
c. A previous categorization scheme prepared for EPA which
employed unit processes to synthesize the raw waste
loads. This method was also judged too difficult to
implement.
d. The preliminary system developed by EPA in the "interim
guidance" for the textile industry.
e. The system developed by the Institute of Textile
Technology and Hydrosciences in the study for the
American Textile Manufacturer's Institute, Inc., and
Carpet and Rug Institute.
Based on knowledge of the various pollution problems, loads
generated by the different unit operations in the textile industry,
actual and potential waste treatment practices and current
manufacturing and processing practices, these five approaches were
combined and simplified.
The last two methods (d and e) and the present one have in common a
categorization according to the products produced by a mill that in
turn relates to type of wastes.
35
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A comparison of the EPA interim guidance and the ATMI/CRI
categorizations with those used in this study is given in Table 6.
36
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TABLE 6
COMPARISON INDUSTRY-ERA SUBCATEGORIZATION
ATMI
SUBCAThGORIZATION
*
Wool Scouring
«• Wool Finishing
Carpet Backing and Foam
Greige Mills
Specialized Finishing
Woven Fabric Finishing
Knit Fabric Finishing
Carpet Mills
Stock Yarn Dyeing
and Finishing
Multiple Operation Commission
House
Greige and Fabric Finishing
Greige Plus Yarn and
Fabric Mnishing
Combined Materials Finishing
-Stock, Yarn Wovens, Knits
EPA FINAL
SUBCATEGORIZATION
Wool Scouring
Wool Finishing
Dry Processing
Woven Fabric Finishing
Knit Fabric Finishing
Carpet Mills
Stock Yarn Dyeing
and Finishing
Commission Finishing*
calculated by Proraticn
Among Dry Processing,
Woven and Knit Fabric,
and Stock and Dyeing
and Finishing
*-The tenu "Commission Finishing" shall mean the finishing of textile materials,
50 per cent or more of which are owned by others, in mills that are 51 per cent or
more independent (i.e. only minority ownership by companies with greige or
integrated operations); the mills must process 20 per cent or more of their
commissioned production through batch, non-continuous processing operations,,
with 50 per cent or more of their commisssioned orders processed in lots of
50,OOU yards or less.
37
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Categorization
The following factors were considered in establishing subcategories
in the textile industry.
a) raw material
b) age and size of facilities
c) products and production processes
d) location and climate
e) waste treatability
The principal basis for subcategorization is the configuration of
the predominant material being processed. Knit and woven fabrics
are different and each is different from carpet, yarn or other
fibers. Special processes such as wool scouring and commission
finishing provide additional subcategorization. Waste water volume
and characteristics vary widely for the different materials and
processes and support the proposed categorization. Although waste
water volume and characteristics vary significantly, the
treatability of textile wastes by similar biological treatment
methods has been demonstrated. Thus, subcategorization by waste
treatability is not required. Location and climate have a material
effect upon pollution control methodology for any given operation or
segment of the industry. However, the impact of either location or
climate is not sufficient for defining or substantiating
subcategories. (Variability in treatment operation has been taken
into account in Section IX.) Available data indicates that neither
the age nor the size of facilities significantly affects waste
character or water usage. Any effect of size or age is
predominately reflected in the type or size of production facility,
and was taken into consideration through subcategorization based on
different manufacturing processes.
The subcategorizations selected for the purpose of developing waste
water effluent limitations guidelines and standards are as follows:
1. Wool scouring
2. Wool finishing
3. Dry Processing
4. Woven fabric finishing
5. Knit fabric finishing
6. Carpet mills
7. Stock and yarn dyeing and finishing
8. Commission finishing
Subcategories 1 and 2 deal with wool processing; subcategories 3,
4, 5 , 7 and 8 cover the various types of processing for cotton and
synthetic fibers; and subcategory 6 covers the carpet industry.
These subcategories are described in detail below.
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SubcategorY 1 - Wool Scouring
Wool scouring and topmaking is a conveniently separated subcategory
as a significant number of plants perform this function alone. The
initial washing and cleaning of wool generates a wide variety of
organic and inorganic products in the waste effluent. The raw wool
contains suint, dirt, and grease along with oils such as lanolin.
In addition, the preparation and cleaning of wool requires a heavy
use of detergents. Recovery of wool grease has some economic
incentive in that it has market value. However, even with grease
recovery, wool scouring wastes present a highly concentrated waste.
Wool scouring is conveniently separated from other segments of the
textile industry because of its uniqueness. Raw wool (grease wool)
must be wet processed to clean it before the fiber can be dry
processed to produce fiber, yarn or fabric for the further wet
processing steps found in a finishing plant. Neither cotton nor the
synthetic fibers require this initial wet-cleaning. Furthermore,
most wool scouring mills are geographically separate from other
textile operations. Exceptions exist where wool scouring is
physically separated from, but shares the waste treatment plant
with, finishing mills.
The grease wool contains 25 to 75 percent non-wool materials,
consisting of wool grease and other excretions and secretions of the
sheep such as urine, feces, sweat and blood, as well as dirt
consisting of both soil and vegetable matter. Additional materials
that may be present are insecticides (sheep dip), and fugitive dyes
used for identification. This variability in yield and in the
composition of impurities and grease causes a correspondingly
variability in raw waste loads. An average composition of raw
grease wool is 39 percent clean, dry wool, 6 percent regain
moisture, 6 percent suint and associated moisture, a percent wool
wax and U5 percent dirt.
Subcategory 2 - Wool Finishing
Wool finishing could involve the use of certain metalized dyes
peculiar to this fiber which often may result in the presence of
metal ions such as chromium in the waste effluent. In addition,
phenols occur from dyeing polyester blends. Only a small amount of
pure wool is now processed. The bulk of the operations involves
wool-polyester blends which give high BOD loads from the dye carrier
which is used. The resulting wastes are similar to those in woven
Fabric Finishing and Knit Fabric Finishing, but have a higher raw
waste load.
39
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Several major mills have integrated wool scouring and top making
with wool finishing. Such mills can be accommodated by a
combination of Subcategories 1 and 2.
This industry consists of many small mills — most of them in the
North (New England, New York and New Jersey) and most are fully
integrated mills — and about 25 larger mills, mostly in the South
(Virginia, the Carolinas and Georgia).
A sample of 29 textile mills participated in a waste treatment
survey prepared by the Wool Manufacturers Council of the Northern
Textile Association. Of the 29 mills, 25 were wool finishers and 4
were cotton and synthetic mills. Of the 29 mills 7 have completed
tie-ins into municipal treatment facilities; 15 plan to tie into
municipal facilities that are in various stages of construction or
planning; 4 have completed private treatment facilities and 3 have
plans to construct private treatment facilities.
Most small mills do some commission dyeing, and even the larger
mills that are part of the larger corporations commonly perform
commission dyeing. Commission dyeing operations imply a wide range
of fabrics and finishes as well as fiber types.
Probably not more than five mills still do more than 50 percent wool
and wool blends: the rest process primarily other fabrics.
The processes of carding and spinning wool into yarn, and subsequent
weaving or knitting into fabric are included in Subcategory 3,
Greige Mills.
Yarns made from wool are classified into either woolen yarns or
worsted yarns. Woolen yarns are characteristically of loose
construction and composed of relatively short fibers; worsted yarns
are of tight construction with few protruding fiber ends and
composed of selected long fibers (tops). As a result, worsted yarns
are stronger.
Wool finishing has been differentiated from other finishing
categories because of (1) the wide variety of chemicals used to
process wool fabrics and (2) high raw waste loading.
In addition to processing all wool fabrics, today's wool finishing
mills process wool blend fabrics and fabrics made of 100% synthetic
fibers. The percentage of wool used by a woolen mill is based on
market demand and availability of wool. The variety of fabrics
varies from mill to mill, season to season and year to year. Shifts
back and forth between fibers cannot be predicted.
Few of today's wool finishing mills process all wool. Many of the
woolen mills by name handle 20 percent or less wool with the balance
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being woven and knit synthetics. Also, within the 20 percent or
less portion, woolen/synthetic blends (most often with polyester)
usually constitute the bulk of the fabric.
High water usage in the subcategory appears to be a result of
washing after the fulling operation (peculiar to 100 percent wool
fabrics and to some wool blends). Wax lubricants and emulsified oil
are sometimes used in processing wool yarns. These waxes and oils
are difficult to remove and require thorough washing to be removed
properly. Because of the low percentage of wool actually processed
in mills today, and the small amount of sizing used, this category
appears in most ways similar to Subcategory 5, Knit Finishing.
Variations occur in processing, similar to other finishing
categories, in that some fabrics are woven or knit from yarns that
are already dyed, either in the fiber or yarn form. A given mill
may dye and finish part of its production while only finishing the
remainder.
Subcategory 3 - Dry Processing
Dry processing textile operations include products and processes
which by themselves do not generate large effluent volumes (more
than 12.5 1/kkg (1.5 gal/lb) of product). Some operations include
yarn manufacture, yarn texturizing, unfinished fabric manufacture,
fabric coating, fabric laminating, tire cord and fabric dipping, and
carpet tufting and carpet backing. The principal source of effluent
from such processes is the washing and cleaning of equipment.
Manufacturing yarn texturizing and unfinished fabric manufacturing
may be done in a greige goods mill. There are many greige goods
mills, although they carry out mainly dry operations (with the
exception of slashing) and hence contribute little to the overall
waste problems of the textile industry. In many plants the sanitary
BOD load is comparable to the process BOD load. This category
applies equally well to woven or knitted greige goods.
Greige goods manufacturing includes spinning and texturizing of
yarns which require a lubricating oil, similar to mineral oil. This
oil is applied to the fibers or yarns and stays with them, to be
removed prior to dyeing in the dye house. However, some oil finds
its way into the drains because of clean-ups and spills.
Prior to being woven, the yarns are coated with a sizing material to
give the yarn both lubrication and strength that will permit it to
withstand the severe mechanical demands of weaving. Cottons
generally are coated with starch and synthetics with polyvinyl
alcohol. Wool and wool blends are seldom sized, unless the yarns
are quite fine. Since most wool yarns are blends, both starch and
PVA may be used. The slasher, where the sizing is applied, is
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washed down about once a week and thus contributes to the liquid
wastes. Generally the waste flow from the slashing operation
represents a low percentage of the total plant flow.
Greige mills generally manufacture yarn and unfinished fabric. In
general greige mills include the production of woven greige goods,
knit greige goods and greige yarn production. However, knit greige
goods production is almost always combined with a finishing
operation and therefore may be included in the knit finishing
subcategory. Carpets are sometimes backed in a separate plant. The
industrial portion of the waste water consists of equipment washing
which may be performed once a day or once a week. The resulting
waste flow is small, relative to plant size and pounds of product.
It has been estimated that there are 600 to 700 greige woven mills,
80 percent of which are in North Carolina, South Carolina, Georgia,
Alabama and Virginia. Perhaps 20 percent of the 600 have their own
waste treatment plants, with almost all the rest disposing of wastes
at municipal facilities. Less than 5 percent are believed to
dispose of their wastes in waterways without treatment.
Carpet is backed with either latex foam or coated with latex and a
burlap-type woven fabric backing put over the latex. In either
case, carpet backing results in the generation of a liquid latex
waste. Some of the latex becomes hardened, so a mixture of solid
and liquid latex results. Some of this material is collected by
shovelling it into a barrel for landfill disposal. The rest is
washed off by hosing and removed by settling such as alum
coagulation. pH control may also be needed. This pretreatment and
treatment technology is also applicable to processors of coated
fabrics and tire cord fabrics and felts.
Subcategory f£ - Woven Fabric Finishing
This category is one of the most important, because such plants
constitute much of the waste water effluent load in the textile
industry. Integrated woven fabric finishing mills are included in
this subcategory because the greige goods section of these mills
contributes only a small amount to the overall effluent load.
The size removed after weaving is a major contribution to the BOD
load from the plant. Two sizing compounds are commonly employed:
starch and polyvinyl alcohol (PVA) . PVA tends to be less readily
biodegradable than starch and therefore presents a lower BQD5 level
but contributes a high COD level. In addition to high BOD, the
wastes generally have high total dissolved solids, color, and a
variety of dispersing agents. They also may be very alkaline from
the use of caustic soda in mercerizing cottons.
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The dyes and associated additives used in woven fabric finishing
represent the most complicated problem, since the BOD load and color
can vary considerably with the type of dye fabric being processed
and the color effects to be achieved.
Processing steps in this category generally include cleaning the
greige goods, bleaching, mercerizing of cotton (treating with
caustic), dyeing, washing and rinsing, followed by application of
finishes such as soil repellents, anti-statics, etc.
This category encompasses mills which finish woven goods (or
integrated greige goods and finishing mills). It has been estimated
that about 600 mills fall into subcategory 4. About 20 percent
treat their own waste, 75 percent discharge to municipal systems,
and 5 percent have no waste treatment.
This category predominates in the Southeast (North and South
Carolina, Georgia, Virginia, Alabama), but there are some large
operations in New York and New England.
Subcateqory 5 - Knit Fabric Finishing
The main difference between woven and knit fabric finishing is that
the sizing/desizing and mercerizing operations are not required for
knits. Although desizing and mercerizing are not required, these
fabrics do contain lubricants and anti^static agents. Therefore,
the raw waste loads are different for all parameters as compared to
woven fabric finishing.
The knitting industry is characterized by a large number of plants
and a structure organized along specialized product segments. The
major segments are knit fabric piece goods, hosiery, outerwear, and
underwear.
While the industry has shown substantial growth in value of
shipments, it has been estimated that through consolidation and
other factors the current number of plants in this industry is about
2500. Of this number, it has been estimated that about 1100 plants
have only dry operations. These are plants such as sweater mills in
the outerwear segment, which knit goods from purchased or commission
dyed yarns, or mills which have finished goods dyed on a commission
basis and therefore, have no process water requirements. Most of
the sweater mills are located in the Northeast. In those isolated
instances where sweater or similar mills dye their own yarn, these
mills should be subject to subcategory 7 guidelines.
Of the 1400 plants believed to have wet process operations, it has
been estimated that 85 percent discharge to municipal treatment
systems. The great bulk of these are hosiery plants (700-800)
located primarily in North Carolina, Tennessee, and Pennsylvania.
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The knit fabric segment of the industry has about 540 plants. These
plants are the source of finished knit piece or yard goods for the
apparel, industrial, and household goods trades, and also serve to
augment supplies of fabric to underwear and outerwear manufacturers.
These plants are the main subject of subcateogry 5. The large knit
fabric plants are located mainly in North and South Carolina and
Georgia, but substantial numbers are also located in New York, and
Pennsylvania.
Subcategory 6 - Carpet Mills
Carpet mills form a distinct part of the industry although their
effluents are similar in many ways to those of Subcategory 5, Knit
Fabric Finishing. Carpets use mostly synthetic fibers (nylon,
acrylics and polyesters) but some wool is still processed. As in
Subcategory 2, Wool Finishing, such wool carpet mills produce
synthetics as well. As a result, no Subcategory for wool carpets is
proposed.
Tufted carpets account for well over 65 percent of the plants and 86
percent of the dollar volume, and constitute 74 percent of the
employment in this industry. Therefore, the guidelines are
generated principally around this segment. About 70 percent of the
industry is located in Dalton, Georgia and these mills are connected
into the municipal treating system. However, the remaining carpet
mills are of sufficient quantity to warrant effluent guidelines.
Tufted carpets consist of face yarn that is looped through a mat
backing (mostly polypropylene, some jute), and dyed or printed.
The dominant face yarn is nylon, followed by acrylic and modacrylic,
and polyester; the latter two groups total less than 50% of the
poundage of nylon. Since dyeing of these fibers in carpets differs
little from dyeing fabric, the dyeing descriptions for these fibers
given in other categories applies here. Beck, continuous dyeing,
and screen printing are practiced.
Subcategory. 7_ - Stock and Yarn Dyeing and Finishing
Yarn dyeing and finishing are different from woven fabric finishing
because there is no sizing and desizing operation. They are
different from knit fabric finishing because of their mercerizing
operations and water use. The combined differences are sufficient
to justify a separate category. The waste loads from this type of
plant can vary more than those from other types of integrated
textile mills or finishing mills. Many multiple-operation,
commission houses fall under this category.
44
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Subcategory 7 includes plants which clean, dye and finish fiber
stock or yarn. The plants may or may not have yarn spinning
facilities. Sewing thread, textile and carpet yarn are typical
products.
It has been estimated that 750 plants fall into this category. Most
(probably 80 percent) dispose of their wastes at municipal
facilities. We believe that 5 to 10 percent treat their own waste
and the rest have no waste treatment facilities.
About 60 percent of yarn dyeing and finishing is performed in
Virginia, North Carolina, South Carolina, Georgia and Alabama, with
the remainder distributed across the eastern U.S. and the Far West.
Subcateggry 8 - Commission Finishing
Commission finishing plants may process raw materials into products
in any of the above textile subcategories. The common denominator
is that these plants process greige goods on a commission basis.
The main difference between these plants and those of other
subcategories is their ability to control the fabrics and finishing
specifications demanded. Because "commission house" is an economic
description of a plant, some "commission houses" can control the
processing fabrics and are not characterized by extreme variability
in waste load and waste composition. Other "commission houses"
cannot control the scheduling and flow of material through the plant
and these operations are characterized by an extremely high
variability in waste load and composition. Thus, commission
finishing subcategory plants are defined as manufacturers of textile
materials owned outside their organization. Furthermore, commission
finishing subcategory plants must produce 20 percent or more of
their commission production from batch operations and process 5C
percent of their commission orders in lots of 5,000 yards or less.
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SECTION V
WASTE CHARACTERISTICS
INTRODUCTION
Many of the mechanical operations used in the manufacture of textile
fabrics are common to the industry as a whole and the character of
the waste waters are similar. Typically, the textile fibers are
combined into yarns and then the yarns into fabrics. After the
fabrics are manufactured, they are subject to several wet processes
collectively known as finishing and it is in these finishing
operations that the major waste effluents are produced.
In Section III wool, cotton and synthetic fiber and fabric finishing
operations were briefly described. General descriptions of the
manufacturing processes were given in Section IV for the purpose of
industry subcategorization. In this section the waste waters from
each operation within each subcategory are characterized.
The principle parameters used to characterize waste effluents were
the flow, biochemical oxygen demand, chemical oxygen demand, total
suspended solids and oil and grease. In addition, chromium, phenol
and sulfide can be present. As discussed in Section VI, these
parameters are considered to be the best available measure of the
waste load.
Subcategory 1 - Raw Wool Scouring
The rr-.w waste from raw wool scouring is different from the waste
from ail other categories used in this study: it contains
significant quantities of oil and grease, even after in-process
recovery. The wool grease constitutes a special problem in
treatment since it does not appear to be readily biodegradable.
Therefore, a grease recovery step is important to reduce pollution.
Sulfur is brought in with the wool, as well as phenolic and other
organic materials derived from the sheep urine, feces, blood, tars,
branding fluids and insecticides used in sheep-dips. These items
appear randomly in the effluent.
Wool scouring is generally performed in a series of scouring bowls.
In these scouring bowls, the heavier dirt and grit settles to the
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cone-shaped bottoms where it is blown down once an hour or so, and
carried to the treatment plant by scour liquor.
The scour liquor, after picking up the soluble and less heavy dirt
and grit, is piped to a separation tank where further settling of
dirt and grit occurs. This material is also blown down and carried
to the treatment plant once a day, or more often if the dirt content
of the wool is high.
From the separation tank the scouring liquor is processed to break
the emulsion and recover the wool grease. Two methods are commonly
used to do this: centrifuging and acid-cracking.
In centrifuging (as shown in Figure 1) the top low-density stream
contains concentrated grease, which is further dewatered in
additional centrifuges to yield the recovered, unrefined wool
grease. The medium-density stream is combined with the relatively
clean bottoms from the auxiliary centrifuges and recycled to the
wool scouring train as fresh scour liquor. The high-density-bottoms
streams consists mainly of dirt and grit, and is sent to the
treatment plant.
An alternative means to break the grease emulsion for wool grease
recovery is the acid-cracking grease recovery system, also shown in
Figure 1. Sulfuric acid is added to the scour liquor to break the
grease/water emulsion. Heating the mixture increases the efficiency
of separation. The grease is separated from the liquor in a
settling tank and recovered. The liquor is then treated with lime
to neutralize the acid a'nd subsequently passes through the waste
treatment plant.
In the centrifugal method, about 60 percent of the grease is
recovered: the remaining HO percent is attached to the dirt and
grit. In the acid-cracking method, pilot plant performance
indicates a 98 percent recovery of grease from the degritted liquor.
Grease yield, in total , is 8 to 15 percent by weight of the greasy
wool, and this constitutes 50 to 65 percent of the wool grease
initially present. (Ref. 141). Note that 1-3 percent of the wool
grease present in the grease wool is allowed to remain in the wool
as a conditioner.
Also, alkaline scouring has been used in which soda ash is added to
the wash water. The soda ash combines with some of the wool grease
to form a natural soap, thereby requiring less detergent but also
lowering recovered wool grease yield.
Some "raw" wools, mostly the Australian and New Zealand wools, are
pre-scoured at the source. However, this fact does not appear to
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significantly affect this analysis of U.S. raw wool scouring mills.
Note that scoured wool is often converted into "tops" at the same
mill. In this operation, the short fibers are separated
mechanically from the long ones; the long fiber "tops" are used for
worsted yarn and the short fibers are used to blend into woolen
yarns. No added pollution occurs. Water load is increased by air
conditioning and air scrubbing.
Subcategory 2 - Wool Finishing
Wool finishing has been differentiated from other finishing
categories because of 1) the wide variety of chemicals used to
process wool fabrics, 2) its peculiar BOD loadings, and 3) the
higher water usage per pound of product.
Since many wool mills investigated are working on blends,
principally polyester, carriers such as orthophenol, phenol,
diphenyl, or benzoic acid derivatives will be present at significant
levels in their raw wastes. Phenolics appear to be losing favor
because of their odor, but current practice includes them and they
will be present in most wool-blend mill wastes.
The Subcategory 2 mills have a higher water usage rate than any
other finishing category. The heaviest contributor appears to be
the rinsing after fulling. The wet unit processes are described in
more detail below.
Heavy Scour
Heavy scouring is the term applied to the washing of the fabric by
the use of detergents, wetting agents, emulsifiers, alkali, ammonia,
or various other washing agents. The purpose of this heavy scour is
to remove oils, grease, dirt, fulling solutions, emulsified oil,
lubricants or any other substances that are either introduced in
prior processing steps or that are carried to the finished fabric
from the raw stock.
This process is one of the most important steps in wool finishing
because if all of the foreign materials are not completely washed
out, the finished fabric is susceptible to rotting, smelling,
bleeding and will not accept dyes uniformly.
Fancy goods, in contrast to piece dyed goods, are only scoured prior
to mechanical finishing. Piece dyed goods, on the other hand, must
be scoured completely prior to the dyeing step. The weight, foreign
material content and degree of felting of the fabric all have a
direct bearing on the degree of scouring required.
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Heavy weight, closely woven fabrics with a high percentage of
recycled wool require very heavy detergents, long wash times and
extensive rinsing to clean the goods. High organic and hydraulic
loadings are associated with this type of fabric. Light open goods
with a low percentage of wool generally scour more easily with
lighter detergents, shorter wash times and less rinsing resulting in
lower organic and hydraulic discharges.
Some mills produce both types of goods at the same time and relative
proportion of each type will vary greatly causing great fluctuations
in organic hydraulic discharge. Also some mills produce only light
open goods while others produce heavy, close woven fabrics. The
majority of finished product weights range from 12 ounces per yard
to 26 ounces per yard; however, because of the differences in raw
stock and felting requirements the hydraulic and organic discharges
may differ greatly.
Carbonizing. Carbonizing consists of soaking the fabric in strong
sulfuric acid, squeezing out the excess, and then heating the wet
fabric in an oven. The hot acid reacts chemically with vegetable
matter and any cellulosic fiber contaminant and oxidizes these
contaminants to gases and a solid carbon residue. The fabric is
then passed between pressure rolls where the charred material is
crushed so that it may be separated by mechanical agitation and
flowing air. A solid waste is produced, and the acid bath is dumped
when it becomes too contaminated for further use, about once every
two days.
Fulling. Fulling is usually used on 100 percent woolen fabrics but
not usually on woolen/polyester blends and to a lesser degree on
worsteds. Since this operation stabilizes the dimensions of the
wool by "felting" it, the blends usually do not need it, nor do the
worsteds, since they are a very tight yarn and weave to begin with.
Fulling is accomplished by mechanical work performed on the greige
goods while they are in a bath of detergent and water. Detergent is
added as needed but no effluent occurs until the following washing
step. This is true of both "dry" and "wet" fulling except that in
the "wet" fulling, the water bath is dumped about once every 2 to 3
days. In "dry" fulling, just enough water is picked up by the
fabric to lubricate it so the fabric is not standing in water before
its turn in the fulling device.
The fulling is followed by extensive rinsing to prevent rancidity
and wool spoilage. This step produced over 50 percent of the
hydraulic load in an all-woolen mill investigated.
Crabbing. Crabbing is the name given to the operation used to align
the fabric rectilinearly. Since the fabric comes in wet and goes
out wet, no effluent of significance occurs.
50
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Pre-Scour. The pre-scour step is a final cleaning of the greige
goods prior to dyeing. Often, if a light scour or fulling is
performed before dyeing, the pre-scour step is not used. On
sensitive dyeing, however, both light scour and pre-scour are
sometimes used. Detergents and wetting agents are added. This and
subsequent dyeing and rinsing steps are performed in becks.
Dyeing. In the dyeing process, the fabric is dyed in atmospheric
becks or pressure equipment. Pure wool fabric is dyed only in
atmospheric becks, but blends (mostly with polyester) are dyed in
either atmospheric or pressure equipment. Knit woolen blend fabrics
also are dyed in either atmospheric or pressure becks, but most
often they are dyed in jet becks, a variation of the pressure beck
that is supposed to reduce physical damage to the knits.
In conventional becks, the fabric is sewn into a long tube that
alternately soaks in a tub and then is pulled up and over a large
diameter slatted wheel. In a jet beck the fabric is pulled up and
put back in the tub by the action of the dye liquor being pumped
through a venturi and carrying the fabric with it. Pressurizing of
dyeing equipment is desirable for dyeing the polyester portion of
the fabric, since little or no carrier need be used. At atmospheric
pressures large quantitites of carriers are required to swell the
polyester fiber and enable the dye molecules to penetrate.
In the dyehouse, the operation usually consists of filling the
dyeing machine with water and a detergent for scouring (pre-scour,
described above). The scour water is dumped and the beck is
refilled with water and a wetting agent. After the fabric is wet-
out and the temperatures raised somewhat, the dyestuffs are added
*• and the beck brought up to temperature (95°C- 205°C in atmospheric
machines, higher in pressure units). After 2 to 4 hours, 90 percent
or more of the dye is exhausted, and the dye bath is discharged to
- the sewer. This dye step is followed by a clear water rinse. Since
the dyes are very expensive, effort is made to assure as high an
exhaustion level as possible.
Blends are sometimes dyed in a single bath, sometimes in two
separate baths. Therefore, the hydraulic load can from this unit
process increase by 50 percent in the case of two baths (including a
rinse step after all dyeing is completed).
The more commonly used dyes for wool or wool components in blends
are acid dyes or metallized dyes. Others used to a small extent are
mordant dyes or fiber reactives. The use of mordant (chrome) dyes
is diminishing.
As mentioned, the metallized dyes used for wool are very fast (i.e.,
do not fade or rub off readily). Hence on 100 percent wool cloth,
these dyes are often used. These dyes have a very high affinity for
51
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wool, even under mildly acidic conditions and at low temperatures
(below 205°F). Hence, these dyes are almost completely exhausted
from the bath and only a small amount of metallic ions (chrome) will
be expected in the effluent. In the blends, however, the dyes used
for polyester and other synthetic fibers have poorer fastness, so,
in these blends many woolen mills have converted to non-chrome dyes.
As a result, an all-wool mill may be expected to have some chrome in
its effluent, but in a wool-blend mill, the chrome will be
considerably less or even non-existent. Rework levels appear to be
3 to U percent of total production. When goods are reworked, they
are either redyed to a darker shade, or stripped with reducing
chemicals, rinsed and redyed.
After it is dyed, the fabric is cooled with clear water and rinsed
until the dump or overflow water is clear.
Finishing. After it is dyed and rinsed, the fabric is removed from
the beck and, when used, soil repellents and other finishing agents
are padded onto it. Next, the fabric is dried and any subsequent
dry finishing operations — principally shearing (solid waste) and
pressing (steam condensate) — are performed.
Mothproofing is accomplished with Mitten-FF for government fabrics
or with Dieldren for certain other specialized fabrics. Spillage
appears to be the only way this material might find its way into the
waste waters.
Any of the finishing chemicals can appear in the waste when the
padding equipment is dumped and washed.
Subcategory 3 - Dry Processing
Waste at greige mills constitute residues in size boxes at the end
of a day or a week, and water used for clean-up. The volumes of
textile wastes in a greige mill are small. Significant amounts of
water used in a greige mill (e.g., cooling water) may not enter the
waste treatment plant.
A typical sizing formulation is composed of a film-forming material,
a fatty or waxy component, and water. In some formulations, a
water-soluble dye may be used to give the grey cloth an identifying
color. A preservative may be used in some sizing mixtures.
The most common film forming materials are starch, polyvinyl alcohol
and carboxymethyl cellulose. Other sizes, such as polyacrylic acid
and styrene-maleic anhydride polymer, are used occasionally in
weaving special cloths.
Starch is a traditional sizing material, but in the past several
years the volume of polyvinyl alcohol used in the textile industry
52
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has increased substantially, since starch does not adhere well to
the synthetic hydrophobic fibers. In many cases, mixtures of starch
and polyvinyl alcohol are used.
When formulations based on starch are used, the add-on of size
amounts to 10 to 15 percent by weight of warp yarn. When polyvinyl
alcohol is used, a lower add-on, 3 to 8 percent by weight of the
fabric, is typical. The range of add-on depends on cloth
construction factors such as warp yarn diameter, "tightness" of the
fabric, etc.
The total waste load at a dry processing mill is typically greater
than 90 percent sanitary and the remainder is industrial.
Treatability of dry processing mill wastes is often related to the
size used. Starch is very readily degraded biologically, and may be
given a preliminary enzyme treatment to improve biodegradability.
On the other hand, polyvinyl alcohol is consumed by organisms
relatively slowly, though recent studies show that organisms
acclimate to polyvinyl alcohol. (See Subcategory 4 below.)
A special waste, peculiar to the carpet backing industry, exists
because of the use of foamed and unfoamed latex backing. The latex
is not soluble in water but is used in a highly dispersed form;
hence suspended solids and COD could be a problem unless they are
coagulated. This stream (from equipment washdown once a day to once
a week) is usually segregated,, acidified to hasten coagulation, and
settled before it joins dyehouse wastes. An alternative to latex
backsizing is the application of a hot melt composition. The hot
melt size does not contribute to the aqueous waste disposal load.
53
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Subcategory <4 - Woven Fabric Finishing
The wastes associated with finishing woven goods result from removal
of foreign material during the cleaning and from the various
chemicals used in finishing the fabric.
Desizing
Enzymatic removal of starch size generates starch solids, fat or
wax, enzyme, sodium, chloride and wetting agent in the effluent
stream. The waste contains dissolved solids (both organic and v
inorganic), suspended solids, and some fat or wax; it has a pH of 6
to 8, is light colored, and contains no toxic materials.
Sulfuric acid removal of starch size generates waste containing
starch solids, fat or wax and sulfuric acid. It contains organic
and inorganic dissolved solids, suspended solids, and some oil and
grease. It has a pH of 1 to 2 and is relatively light colored.
After the desizing agent has been applied, the goods are placed in a
bind or a steamer to provide the residence time required. Residence
time in storage bins are typically 12 hours or more. If elevated
temperatures are used by employment of J-boxes or steamers the
residence time is reduced to 30 minutes at 180°F or a few minutes at
210° to 212°F. Finally, the goods are washed with water to remove
the decomposed starches from the fabric. Polyvinyl alcohol and
carboxymethyl cellulose are both removable with water alone. The
goods are washed with water at 180°F or higher on washers without
the use of steamers, J-boxes, or padders. Desizing these materials
will thus contribute suspended solids, dissolved solids and oil and
grease. Since these sizes are used at about one-half the *
concentration of starch, the total solids generated in the waste
stream are about one-half the level corresponding to starch use.
When mixtures of starch and polyvinyl alcohol are used, desizing may "
involve the use of enzyme (to solubilize the starch) and water;
total wastes generated would be intermediate between that developed
by either size used alone.
Desizing may contribute 50 percent or more of the total waste solids
in a woven goods finishing mill.
The contribution of starch to BOD of waste streams has been
documented many times. On the other hand, polyvinyl alcohol has
been considered very slowly biodegradable, and as such, a major
source of COD. Recent studies performed by producers of polyvinyl
alcohol, in cooperation with textile mills, indicate that biological
waste systems will develop organisms acclimated to polyvinyl
alcohol, and when this has occurred, biodegradation is relatively
rapid and complete.
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Scouring
Scouring, using 2 to 3 percent sodium hydroxide, is done to remove
much of the natural impurities of cotton; phosphate, chelating
agents and wetting agents may be used as auxiliary chemicals. The
synthetic fibers require much less vigorous scouring; sodium
carbonate and a surfactant may suffice. In the case of
cotton/synthetic blends, Varsol may be used in conjunction with the
aqueous scouring liquor.
The operation known as kier boiling is now seldom employed to scour
desized cotton and cotton/polyester, woven fabrics. The kier is a
large vertical cylindrical pressure vessel which can hold up to
several tons of fabrics. The goods (in rope form) are plaited into
the kier by the kier plaiter, the covers are installed, and the
scouring chemicals are recirculated through the goods and an
external heat exchanger for temperature control. An aqueous mixture
of sodium hydroxide, soap and sodium silicate is employed at
temperatures of up to 220°F and pressures of 10 to 20 psig. The
goods are scoured for 6 to 12 hours. The kiers are then cooled by
recirculation of cooling water and the goods are displacement
washed. In certain instances, difficult fabrics are double-scoured.
The scouring step is designed to remove fats, waxes and pectins from
the woven fabric.
Certain heavyweight fabrics normally are not processed in rope as
required for kier boiling since creases result in streaks in
subsequent dyeing steps. These goods are therefore processed in an
open-width boil-out machine, also known as the progressive jig. The
jig is loaded with a scouring solution and the goods are fed through
it continuously, from roll to roll and the temperature and residence
time are maintained for proper scouring of the goods. The goods are
wound onto rolls in the machine and maintained in contact with
scouring liquids for the necessary period. Then they are unrolled
through wash boxes and folded into a cloth truck or onto a roll.
The scoured cotton may be used directly for producing dark shades or
may be bleached by padding through hydrogen peroxide solutions, and
subsequently washed, neutralized, and dried before dyeing.
Scouring liquors are strongly alkaline (pH greater than 12), and
dark colored due to cotton impurities. They contain significant
levels of dissolved solids and oil and grease. A modest level of
suspended solids results from the presence of cotton impurities.
The natural cotton impurities removed from greige fabric by scouring
contribute BOD and are biodegraded rapidly.
55
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Scouring of cotton/polyester greige blends generates the same waste
in proportion to the amount of cotton in the blend.
Scouring of synthetic woven goods generates a low level of dissolved
solids from surfactant, soda ash, or sodium phosphate.
Mercerization
Physically, mercerization swells the cellulose fibers as alkali is
absorbed into them, with higher concentrations, longer residence
times, and lower temperatures favoring greater swelling. The
mercerization step is conducted with the fabric either under tension
or in the slack condition, with tension mercerizing favoring
increases in tensile strength and slack mercerizing favoring
increases in abrasion resistance.
Mercerization is normally conducted continuously; the operation
consists of the following steps:
(a) A scutcher and water mangle are employed to open the
goods from the rope form, and a mangle is used to
dewater the goods to a uniform moisture
concentrat ion
(b) A multiple-contact saturating operation is conducted
usually with three saturating bowls. The goods are fed
through the system continuously which provides suffi-
cient residence time and contact to completely saturate
the fabric with caustic soda solution.
(c) Timing cans are employed to increase the residence time
of the fabric in the sodium hydroxide solution.
(d) A tenter frame is employed to maintain the fabric under
tension as the fabric travels through the system and the
actual mercerization of the cellulose takes place.
(e) At the end of the tenter frame is a washing system that
includes water sprays, vacuum units and wash water
heaters and re-circulators to wash the fabric and
reduce the caustic content while the fabric is still
under tension in the tenter frame.
(f) The fabric is given a final wash, which
removes the remainder of the sodium hydroxide from the
fabric and reduces the residual pH to an acceptable level
(i.e., 8.5).
Mercerization wastes are predominantly the alkali used in the
process. The waste stream contains high levels of dissolved solids,
56
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and may have a pH of 12 to 13. Small amounts of foreign material
and wax may be removed from the fiber, and will appear as suspended
solids and wax in the wastes; these materials will contribute a
small BOD load.
In most mills, caustic soda is recovered and concentrated for re-
use, thus, saving chemical and avoiding a sizeable waste load,.
Estimates have indicated that recovery of mercerizing caustic is
justified when the caustic use is more than 5 million pounds per
year (dry), and concentration of the alkali is not permitted to fall
below 2S.
Bleaching
The following process units constitute a typical, continuous
peroxide bleaching range, using J-boxes for storage:
Washing. The goods are washed, using either open width or rope
washers to ensure removal of converted starches from the desizing
step.
Caustic Saturator. As the goods continuously leave the washer they
are squeezed through rolls to a minimum water content and then
saturated with sodium hydroxide solution in additional squeeze
rolls. The goods may be in either rope or open width form, but must
remain in the saturator long enough to permit them to become
completely saturated with sodium hydroxide solution.
Caustic J-BoxA The goods are then fed continuously to the caustic
J-box, whose function is to saturate the cloth for the necessary
length of time at the desired temperature (205°-210°F). The
throughput of the J-box is controlled to provide a residence time
ranging from 40 minutes to one hour, resulting in saponification of
natural fats and waxes carried in the cotton.
Caustic Washers. The caustic solution is then removed from the
fabric by countercurrent washing, usually with large quantities of
hot water to ensure complete removal.
Peroxide Saturator. The peroxide saturator is similar to the
caustic saturator. It contains a solution of hydrogen peroxide and
sodium silicate in sufficient concentrations to retain 1.5 percent
of the hydrogen peroxide and 1.5 to 3 percent of the sodium silicate
based on the dry weight of goods.
Peroxide J-Box. The design and operation of the peroxide J-box is
the same as for the caustic J-box. The unit is operated at about
200°F, with a residence time that varies from 40 minutes to 1 hour
to bleach the fabric.
57
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White^JMashes. The bleached goods are now washed to final purity
before piling into bins or going directly to the dryer. Hot water
is preferred for washing, but cold water is employed in certain
instances. Flow meters are employed to regulate the flow of fresh
water, and countercurrent conditions are maintained.
In certain instances, two stages of bleaching are operated,
sometimes with sodium hypochlorite in the final stage.
Hypochj.gri.te Saturator., The hypochlorite saturator is similar to
the caustic and peroxide saturators. Its purpose is to apply a
solution of sodium hypochlorite to the fabric to complete the
bleaching operation. The solution is maintained at room temperature
and the quantities are continuously monitored in order to control
the bleaching operation.
Hypochlorite J-Box. The operation of the hypochlorite J-box is
similar to those discussed before, except that it is operated at
ambient temperatures. Residence times are similar to those employed
in peroxide bleaching, and the same unit may be employed for
hypochlorite and peroxide bleaching at different times.
Washers. Two washers are normally required to neutralize and wash
the goods after hypochlorite treatment. At least a portion of the
first washer is used to apply sodium bisulfite or sulfur dioxide
solutions to neutralize excess bleaching chemicals.
Steamers. In open width bleaching ranges, steamer units may be used
instead of J-boxes to store goods after they have been impregnated
with caustic or bleaching solutions. These are particularly useful
in processing heavyweight fabrics.
Sm^ll Qp_en Width J-Boxes. More recent bleaching technology employs
a more concentrated solution and more drastic operating conditions
and has resulted in the development of the small open width J-box
which permits effective bleaching with residence times of only 10 to
15 minutes.
Continous P£essur.e Scouring and Bleaching. The newest type of
steamer for bleaching ranges is an enclosed type with pressure locks
and seals. This enables the steamers to be operated as a pressure
vessel and the reaction time for the chemical is reduced from UO
minutes to only one to two minutes. The treatment of fabrics is a
function of time, temperature and concentration. The increased
temperatures made possible by pressure steamers reduce the time
needed for complete chemical reaction.
The problems associated with equipment designed for operation at 25
psig and for continuous entry and removal of continuous webs have
posed a substantial design problem. However, several machines are
58
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now available with satisfactory sealing devices, so they may perform
well at these pressures. Some of these units utilize rolls as a
sealing mechanism and others have developed a system involving a lip
seal. In addition there are reports of pressure steamers which may
be operated at pressures up to 45 psig and develop temperatures of
292°F, resulting in residence times only of one or two minutes,
Sodium Chlorite Bleaching. Although sodium chlorite bleaching had
shown some success in the bleaching of man-made fibers, the use of
sodium chlorite has been prohibited by OSHA.
Hydrogen Peroxide Bleaching. Bleaching with hydrogen peroxide
contributes very small waste loads, most of which are dissolved
solids. The dissolved solids are both inorganic (sodium silicate,
sodium hydroxide and sodium phosphate) and organic (a surfactant and
chelating agent). The waste stream contains a low level of
suspended solids when goods containing cotton are bleached.
Dyeing
Dyeing is the most complex of all textile finishing processes.
Table 7 shows the dyes used in the textile industry, the fibers they
are generally used to color, and the relative amounts of each dye
used by the industry.
When textiles are dyed, a sufficient amount of the dyestuff is used
to make the shade. Various other chemicals may be used to help
deposit the dye, or to develop the color. Dye loadings vary widely
even with a particular dye class, depending on the weight of fabrics
being treated and the depth of color desired. The range of
chemicals employed in dyeing also varies widely from place to place
and operation to operation, and depends substantially upon the
dictates of the marketplace.
Table 8 presents a summary of chemicals used in application of dyes
to textiles. Dyed goods are generally, but not always, washed and
rinsed to remove excess dye and chemicals from the cloth. Washing
may involve use of a detergent, and also may involve the use of soda
ash or a sodium phosphate.
The chemical used in dyeing depends significantly on the dyeing
procedure. Both batch and continuous dyeing are practiced, and both
may be employed in the same finishing plant.
Textile goods are dyed continuously when the demand for a single
shade is sufficiently high to justify the necessary equipment.
Production of denims, in which the warp yarns are dyed continuously,
is one example; no special chemicals are required as a result of
dyeing continously. In Thermosol dyeing, which is practiced on
woven cotton (or rayon) or polyester blends, a dye blend is padded
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Dye Types
Acid
Azoic
Aniline Black
Basic (Cationic)
Developed
Dye blends
Direct
Disperse
Fiber-reactive
Fluorescent
Indigo
Sulfur
Vats
Natural
Oxidation Base
Mordant
Pigments
TABLE 7
Types and Amounts of Dyes Used in the Textile Industry
Acrylic Cotton
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Poly- Polyester Nylon/ Amount
Wool Acetate Rayon ester PE/cotton Nylon Cotton Used %
X
X
X
X
X
X
X
X
X
X
X
X
X
10
3
X
X
X X
X
X
X
X
X
X
X
X
X
—
X 17
X 15
X 1
XX 1
X
10
26
Approximate percent of total textile use. Usage of Dyes for which amounts are not shown totals approximately
10 per cent (not including dye blends).
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on the fabric, which is then dried and heated, washed and dried.
Thermosol dyeing requires the use of a migration inhibitor (usually
a gum such as soduim alginate) in the pad bath in order to obtain a
uniform application of the dye.
Piece dyeing, on runs which are not long enough to justify
continuous processing, is normally performed in becks or jigs,
operated at boiling temperature, or in a sealed pressure vessel,
operated at 250°F to 270°F. In modern units, the entire dye cycle
(including washing and rinsing) is controlled automatically.
Pressure equipment usually requires use of less carrier; wastes are
decreased correspondingly.
Dyeing processes contribute substantially to textile wastes. Color
is an obvious waste. A high level of dissolved solids is expected.
Suspended solids should be low. Carriers, which are essential for
dyeing polyester and acetic acid, have high BOD. Sodium
hydrosulfite has a high immediate oxygen demand. Plants using
sulfur dyes will contain sulfides in the raw waste. Dichromates may
appear when sulfur dyes are used.
Some of the wastes from dyeing textile fabrics are related to the
production equipment and to the size of. the mill. On long runs,
where continuous Thermosol dyeing of synthetics or synthetic blends
can be justified, carriers are not required; the gum used as a
migration inhibitor will contribute a low BOD.
Table 8 shows alternative chemicals that may be used as substitutes
for sodium dichromate. Controls are available for the reduction of
vat dyes and their reoxidation; use of the controls could minimize
pollutants.
Printing
Printing involves application of dyes or pigments in the form of a
pattern on to fabric. Dyes penetrate and color the fiber; pigments
are bonded to the fabric with a resin. In general, the formulated
print paste is applied to one side of the fabric only.
The auxiliary chemicals used in printing are included in Table 8.
In addition to the dyes and auxiliary chemicals, a thickener is used
to give the print paste the desired viscosity for the method of
printing and the pattern to be printed. The types of gums commonly
used are locust bean, guar, alginate, starch and combinations of
these gums. Urea, thiourea, and glycols are used in many print
formulations.
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The same general formula is used for pigments regardless of the
fiber being printed. The pigment systems include the pigment, resin
binder, latex, emulsifier, varsol, thickener (optional), and water.
The important dye classes and fibers used in printing are listed
below.
Dye^Class Fiber
Vats, Fiber Reactives, Pigments Cotton, rayon
Acid Nylon
Disperse Polyester, triacetate,
acetate
Cationic Acetate, acrylic,
polyester
"Dybln," Pigments Polyester/cotton blends
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Table 8
Chemicals Used in^Apiglication of Dyes1
Dye Type
Vat
Direct
Disperse
Sulfur
Acid
Cationic
Auxiliary Chemicals Necessary
sodium hydroxide
sodium hydrosulfite
dispersing agent
hydrogen peroxide
acetic acid
sodium perborate alternative
sodium chloride
sequestering agent
sodium sulfate
orthophenylphenol
butyl benzoate carriers
chlorobenzene
acetic acid
dispersing agent
and many other carriers
sodium sulfide
sodium carbonate
sodium dichronate
acetic acid alternatives
hydrogen peroxide
acetic acid
acetic acid
ammonium sulfate
ammonium acetate
sulfuric acid
sodium sulfate
monosodium phosphate
acetic acid
formic acid
oxlaic acid
sodium sulfate
sodium acetate
ethylene carbonate
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Table 8 (continued)
Chemicals Used in Application ^of^ Dyesj
Dye Type Auxiliary Chemicals Necessary
Reactive sodium chloride
urea
sodium carbonate
sodium hydroxide
Developed developer
sodium chloride
sodium nitrite
sulfuric acid
sodium carbonate
hypochloric acid
1(In addition to the chemicals listed, all of the dye types will
usually use a small amount of surfactant. After the dyeing has been
completed, the dyed goods are washed and then rinsed. Washing will
involve use of a detergent as well as soda ash and a phosphate.)
The method most commonly used for developing vat prints is to pad
caustic soda and hydrosulfite to the print prior to flash aging.
The prints are then rinsed in water followed by oxidation with a
solution of acetic acid and hydrogen peroxide or sodium perborate
and then rinsed again. The development of the other dye classes to
their corresponding substrate requires no chemical treatment other
than the auxiliary chemicals used in the print paste. However,
prints of the other dye types are scoured, after development, with
surface active agents and in the case of disperse dyes may be
scoured with a solution of caustic soda and hydrosulfite to remove
any surface dye.
Printing wastes are comparable in many respects to dye wastes.
Printing requires use of gums, which will contribute BOD. Solvents
(Varsol) and glycerine are also common constituents in printing, but
pose no special waste treating problem. Printing pigments will
introduce some suspended solids into the waste. Much of the waste
from printing comes from the cleaning of make-up tanks and process
equipment. These relatively concentrated wastes may justify
segregated treatment, perhaps by incineration.
Other Treatment Wastes
Special finishes such as resin treatment, water proofing, flame
proofing, and soil release endow the fabric with a particular
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property desired by consinners. The property is indicated by the
name, except for resin treatment, which designates finishes that
provide wrinkle resistance. Several of the treatments may be
applied from a single bath.
As would be expected for processes that provide such diverse
effects, the range of chemicals used is very broad. For resin
treatment, a urea-formaldehyde-glyoxal compound ("DMDHEU"), a fatty
softner, and a catalyst (zinc nitrate, magnesium chloride) are used
together. Water repellents include silicones, fluorochemicals, and
fatty materials, each generally applied with a catalyst. Soil
release treatments include special acrylic polymers and
fluorochemicals.
These finishes are generally applied by impregnation of the fabric
followed by squeezing to the desired add-on. The moist material is
dried and then cured by additional heat. The cured fabric is
frequently packed for shipment without rinsing. Most resin-treated
goods are subsequently cured in a garment factory and must not be
rinsed, since the catalyst would be removed.
Wastes from resin treatment, water-proofing, flame-proofing and soil
release are small, since the chemicals are applied by padding,
followed by drying and curing. The chemicals used are diverse and
small amounts of them will enter the wastes.
Subcategory 5 - Knit Fabric Finishing
Fabrics may be knitted from dyed or undyed yarns. Fabrics knitted
from dyed yarn are scoured or dry cleaned to remove knitting oils
and/or waxing. A softener, as an aqueous solution, can be exhausted
onto the fabric or can be padded onto the fabric, as desired.
Typically, knits are processed in piece goods form. The fabric may
be washed on continuous countercurrent washers prior to loading the
fabric in dye machines to remove knitting oils and other
contaminants, or washing may be the first step in the dye machine
cycle. Warm water with a small amount of added detergent is used.
In contrast, woven goods require more extensive treatment to remove
starch or polymeric sizes.
The types of dyeing equipment generally employed include:
atmospheric becks, pressure becks, jet (atmospheric or pressure)
becks, atmospheric or pressure beam dyeing machines, and paddle type
machines. Some plants may also package dye a portion of their
yarns.
The types of dyestuffs, auxiliaries, and conditions employed for
dyeing knit goods are essentially the same as for woven goods of
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comparable fiber composition. See the discussion under subcategory
4 for details of the dyeing operation.
Flat knit fabrics which are beam dyed are first wet batched. In the
wet batching operation, the fabric is passed through a dilute
aqueous surfactant bath at controlled temperatures before being
wound on a perforated beam. This treatment removes some of the
inherent shrinkage, and also enchances penetration of dye liquors in
the dyeing process. There is some waste generation from the wet
batching operation; a small quantity of the dilute bath is dumped
occasionally for cleanup and there is a continual slow drain of
water from the wetted fabric. The wet treatment may remove some of
the knitting oils; however, the fabric can be scoured and dyed in a
single step, or in a two-step operation in the beam machine if the
fabric is particularly dirty.
In knit plants, finishing cotton fabric — e.g., for underwear and
sleepwear — wet process operations also include scouring and
bleaching in kiers or comparable equipment. Plants that process
either cotton or synthetic goods may also have fabric printing
operations.
Most knit fabrics are treated with softners, and resin finished, and
in some cases, with water and oil repellents. These finishes are
applied from a pad bath just prior to final drying and dry finishing
operations. These baths are discharged periodically as required for
fabric lot or formulation changes, but the total daily volume of
discharges is very small.
The main differences between knit and woven fabric wet processing
operations are that knit yarns are treated with lubricants rather
than with the starch or polymeric sizes used for woven goods yarns,
and that mercerizing operations are not employed with knit goods.
Otherwise, the character of the wastes generated from comparable
unit operations performed on different fibers—cotton, synthetics,
and blends—are similar to those found in woven fabric finishing.
Lubricating finishes applied to knitting yarns generally are based
on mineral oils, vegetable oils, synthetic ester type oils, or
waxes, and may also contain antistatic agents, antioxidants,
bacteriostats, and corrosion inhibitors. Specific formulations are
proprietary with the yarn supplier or throwster who applies the
finish. The amount applied varies with the type of yarn; general
levels of add-on by percent of weight on yarn are: untexturized
synthetic yarns, 1 and 2 percent; texturized synthetic yarns, U to 7
percent; and cotton yarns 3 percent or less. These knitting oils
are readily emulsified or soluble in water, and are removed by
washing prior to the dyeing operations.
Subcategory 6 - Carpet Mills
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The carpet industry wastes are very similar in nature to those from
Subcategory 5, Knit Fabric Finishing. When polyester is dyed, the
carriers present the same problem as in other categories. Polyester
carpet is second in volume to nylon, and will continue to grow,
followed by acrylic, modacrylic and wool. Although steps are being
taken to produce polyester fiber that can be dyed without carriers,
disposal of carrier will remain a problem. Most wool used in
carpets is dyed in yarn form, with the use of acid dyes
predominating, thus minimizing chromium use. The pH of carpet
wastes is usually close to neutral.
With the lack of other wet processing steps in the mill, the hot dye
wastes sometimes present a problem to biological treatment systems.
The color problem is similar to that of other finishing categories.
Where carpets are printed or dyed continuously, the thickeners
present a high BOD load, as in fabric printing.
Subcategory 7 - Yarn Dyeing and Finishing
Wastes generated in yarn processing plants will depend substantially
on whether natural fibers, blends, or synthetics alone are
processed.
When synthetics alone are handled, only light scouring and bleaching
is required, and wastes would contain low levels of detergents, soda
ash, sodium phosphate, and perhaps a low bleach level. Wastes for
this step would have low BOD, and dissolved solids. Dyeing would
contribute a stronger waste, primarily due to the carrier in the
case of polyester, and to some acetic acid; wastes, of course, would
contain some color.
Scouring, bleaching, and mercerizing of cotton generate BOD and
color because of the fiber impurities, and a high level of dissolved
solids because of the mercerizing. Because of the relatively low
amounts involved, it does not appear reasonable to recover caustic
soda.
Subcategory 8 - Commission Finishing
A commission finishing Subcategory plant may have a high hydraulic
loading and waste water typically less treatable than that from
other wet finishing operations. Greater water usage is
characteristic of batch processing; additional water usage may
result from the fact that a number of relatively incompatible
processes may be carried out in sequence. The thorough washing and
rinsing required between processes adds further to the hydraulic
loading. Further, batch processing does not easily lend itself to
the advantages of recycling or reuse of water, which is possible in
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many continuous operations. In addition, a wide variety of
processes and specialized treatment must be carried out. A
commission finishing plant also characteristically finishes
"problem" type materials (for example, a commission finisher may be
called upon to dye and finish multi-fiber specialty fabrics, which
require several separate processing steps to achieve the end product
characteristics.)
The chemical content of the effluent from a commission finishing
subcategory plant may continually change, containing effluents from
a wide range of products and processes, which may render the
effluent less treatable than more typical wet finishing operations.
A typical problem is the requirement that many commission finishers
must desize fabrics before finishing or dyeing. Each size agent
requires a specific biological environment for effective degradation
and unscheduled variations in loadings of the sizing agent could
affect the ability of the treatment plant to effectively degrade the
effluent. Further, the materials fed into the treatment system can
be so variable that the biological system may not have an
opportunity to continuously operate in a steady state condition, as
is the case with the more typical finishing plant. Because of the
above factors, the efficiency of the treating system, and hence the
treated waste characteristics, may be subject to substantial
changes.
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SECTION VI
SELECTION OF POLLUTANT PARAMETERS
WASTE, WATER PARAMETERS OF MAJOR SIGNIFICANCE
A thorough analysis of the literature, industry data and sampling
data obtained from this study,, and EPA Permit data demonstrates that
the following waste water parameters are of major pollutional
significance for the textile industry:
Biochemical Oxygen Demand
Total Suspended Solids
Chemical Oxygen Demand
Oil and Grease
Color
Chrome
Sulfide
Phenol
pH
Fecal Coliform
Rationale _for Selectign^gf .Major^Parameters
Biochemical Qxygen_Demand (BOJD51
Biochemical oxygen demand (BOD) is a measure of the oxygen consuming
capabilities of organic matter. The BOD does not in itself cause
direct harm to a water system, but it does exert an indirect effect
by depressing the oxygen content of the water. Sewage and other
organic effluents during their processes of decomposition exert a
BOD, which can have a catastrophic effect on the ecosystem by
depleting the oxygen supply. Conditions are reached frequently
where all of the oxygen is used and the continuing decay process
causes the production of noxious gases such as hydrogen sulfide and
methane. Water with a high BOD indicates the presence of
decomposing organic matter and subsequent high bacterial counts that
degrade its quality and potential uses.
Dissolved oxygen (D.O.) is a water quality constituent that, in
appropriate concentrations, is essential not only to keep organisms
living but also to sustain species reproduction, vigor, and the
development of populations. Organisms undergo stress at reduced
D.O. concentrations that make them less competitive and able to
sustain their species within the aquatic environment. For example,
reduced D.O. concentrations have been shown to interfere with fish
population through delayed hatching of eggs, reduced size and vigor
of embryos, production of deformities in young, interference with
food digestion, acceleration of blood clotting, decreased tolerance
to certain toxicants, reduced food efficiency and growth rate, and
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reduced maximum sustained swimming speed. Fish food organisms are
likewise affected adversely in conditions with suppressed D.O.
Since all aerobic aquatic organisms need a certain amount of oxygen,
the consequences of total lack of dissolved oxygen due to a high BOD
can kill all inhabitants of the affected area.
If a high BOD is present, the quality of the water is usually
visually degraded by the presence of decomposing materials and algae
blooms due to the uptake of degraded materials that form the
foodstuffs of the algal populations.
COD
COD is a measure of the potential oxygen requirement of a wastewater
sample. The test measures potential oxygen consumption and includes
the requirements of components that are not degraded by biological
activity and therefore not measured as BOD.
Materials not degraded biologically may depress D.O. concentrations
by chemical reaction with and subsequent removal of oxygen from
solution. The depletion of D.O. may lead to castastrophic effects
on the ecosystem and to conditions with the effects of depleted D.O.
as described under BOD.
The measurement of COD, by the nature of the test used, gives an
immediate implication of stream condition. By representing
biochemical and chemical oxygen consumption COD is a more accurate
evaluation of the total reduction potential of wastewater.
Textile wastes, being in part non-biodegradable, may effect D.O.
depletion by biological and chemical removal of D.O. from water and
therefore, impose stress conditions on the receiving stream. The
total D.O. depletion potential is better described by COD.
Total Suspended Solids
Total suspended solids include both organic and inorganic materials.
The inorganic components include sand, silt, and clay. The organic
fraction may include such materials as grease, oil, tar, animal and
vegetable fats, various fibers, sawdust, hair, and various materials
from sewers. These solids may settle out rapidly and the resulting
bottom deposits are often a mixture of both organic and inorganic
solids. They adversely affect fisheries by covering the bottom of
the stream or lake with a blanket of material that destroys the
fish-food bottom fauna or the spawning ground of fish. Deposits
containing organic materials may deplete bottom oxygen supplies and
produce hydrogen sulfide, carbon dioxide, methane, and other noxious
gases.
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In raw water sources for domestic use, state and regional agencies
generally specify that suspended solids in streams shall not be
present in sufficient concentration to be objectionable or to
interfere with normal treatment processes. Suspended solids in
water may interfere with many industrial processes, and cause
foaming in boilers, or encrustations on equipment exposed to water,
especially as the temperature rises. Suspended solids are
undesirable in water for textile industries; paper and pulp;
beverages; dairy products; laundries; dyeing; photography; cooling
systems, and power plants. Suspended particles also serve as a
transport mechanism for pesticides and other substances which are
readily sorbed into or onto clay particles.
Solids may be suspended in water for a time, and then settle to the
bed of the stream or lake. These settleable solids discharged with
man's wastes may be inert, slowly biodegradable materials, or
rapidly decomposable substances. While in suspension, they increase
the turbidity of the water, reduce light penetration and impair the
photosynthetic activity of aquatic plants.
Solids in suspension are aesthetically displeasing. when they
settle to form sludge deposits on the stream or lake bed, they are
often much more damaging to the life in water, and they retain the
capacity to displease the senses. Solids, when transformed to
sludge deposits, may do a variety of damaging things, including
blanketing the stream or lake bed and thereby destroying the living
spaces for those benthic organisms that would otherwise occupy the
habitat. When of an organic and therefore decomposable nature,
solids use a portion or all of the dissolved oxygen available in the
area. Organic materials also serve as a seemingly inexhaustible
food source for sludgeworms and associated organisms.
Turbidity is principally a measure of the light absorbing properties
of suspended solids. It is frequently used as a substitute method
of quickly estimating the total suspended solids when the
concentration is relatively low.
Oil and Grease
Oil and grease exhibit an oxygen demand. Oil emulsions may adhere
to the gills of fish or coat and destroy algae.or other plankton.
Deposition of oil in the bottom sediments can serve to inhibit
normal benthic growths, thus interrupting the aquatic food chain.
Soluble and emulsified material ingested by fish may taint the
flavor of the fish flesh. Water soluble components may exert toxic
action on fish. Floating oil may reduce the re-aeration of the
water surface and in conjunction with emulsified oil may interfere
with photosynthesis. Water insoluble components damage the plumage
and costs of water animals and fowls. Oil and grease in water can
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result in the formation of objectionable surface slicks preventing
the full aesthetic enjoyment of the water.
Oil spills can damage the surface of boats and can destroy the
aesthetic characteristics of beaches and shorelines.
Wool wax is a substantial pollutant in the wool scouring
subcategory; in other textile subcategories, other materials
measured as grease and oil are much less troublesome.
color —
Color is defined as either "true" or "apparent" color. In Standard
Methods for the Examination of Water and Wastewater (H) , the true
color of water is defined as "the color of water from which the
turbidity has been removed." Apparent color includes "not only the
color due to substances in solution, but also due to suspended
matter,"
Color in textile waste water results from equipment washup, textile
washwater and from dye not exhausted in the dyeing process.
Color bodies interfere with the transmission of light within the
visible spectrum which is absorbed and used in the photosynthetic
process of microflora. Color will affect the aquarian ecosystem
balance by changing the amount of light transmitted and may lead to
species turnover.
Color bodies discharged to waterways alter the natural stream color
and thereby become an aesthetic pollutant. Unnatural receiving
water color detracts from the visual appeal and recreational value
of the waterways.
Color when discharged to receiving waters has detrimental effects on
downstream municipal and industrial water users. Color is not
treated for in conventional water treatment systems and when passed
to users may result in consumer discontent and may also interfere
with industrial processes which demand high quality water.
Color is found in wastewater throughout the textile industry. Some
colors are water soluble and some are not (dispersed and vat dyes).
Biodegradability is highly variable. Many hues are used in dyeing,
and may appear in wastes; their combination in waste streams
frequently generates a gray or black color. There is no universally
accepted monitoring method. An analytical method developed by the
American Dye Manufacturers Institute (A.D.M.I.) will be used in
evaluating textile effluent color. The analytical procedure and the
calculations required to evaluate color are reported in Appendix A.
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Chromium
Chromium, in its various valence states, is hazardous to man. It
can produce lung tumors when inhaled and induces skin
sensitizations. Large doses of chromates have corrosive effects on
the intestinal tract and can cause inflammation of the kidneys.
Levels of chromate ions that have no effect on man appear to be so
low as to prohibit determination to date.
The toxicity of chromium salts toward aquatic life varies widely
with the species, temperature, pH, valence of the chromium, and
synergistic or antagonistic effects, especially that of hardness.
Fish are relatively tolerant of chromium salts, but fish food
organisms and other lower forms of aquatic life are extremely
sensitive. Chromium also inhibits the growth of algae.
In some agricultural crops, chromium can cause reduced growth or
death of the crop. Adverse effects of low concentrations of
chromium on corn, tobacco and sugar beets have been documented.
Sulfide
Sulfides discharged to neutral receiving waters can be reduced to
hydrogen sulfide. Hydrogen sulfide is an extremely toxic,
odiferous, and corrosive gas. It is very soluble and exists as a
dissolved gas in receiving waters.
Minute concentrations (less than .002 mg/1) of hydrogen sulfide
impart an objectionable odor and taste to water, making it unfit for
municipal consumption.
The proven toxicity of sulfides to aquatic life makes them
objectionable components of the waste stream. Sulfide corrosion of
metal and cement structures are additional problems. In addition to
corrosion, discoloration of structures through sulfide oxidation is
a cause for concern.
Organic sulfer and sulfides are in the waste flow from the dyeing
operation, and are also derived from other processes using
compounds containing organic sulfer.
Phenols
Phenols and phenolic wastes are derived from textile processing
chemicals; petroleum, coke, and chemical industries; wood
distillation; and domestic and animal wastes. Many phenolic
compounds are more toxic than pure phenol; their toxicity varies
with the combinations and general nature of total wastes. The
effect of combinations of different phenolic compounds is
cumulative.
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Phenols and phenolic compounds are both acutely and chronically
toxic to fish and other aquatic animals. Also, chlorophenols
produce an unpleasant taste in fish flesh that destroys their
recreational and commercial value.
It is necessary to limit phenolic compounds in raw water used for
drinking water supplies, as conventional treatment methods used by
water supply facilities do not remove phenols. The ingestion of
concentrated solutions of phenols will result in severe pain, renal
irritation, shock and possibly death.
Phenols also reduce the utility of water for certain industrial
uses, notably food and beverage processing, where it creates
unpleasant tastes and odors in the product.
Fecal Coliforms
Fecal coliforms are used as an indicator since they have originated
from the intestinal tract of warm blooded animals. Their presence
in water indicates the potential presence of pathogenic bacteria and
viruses.
The presence of coliforms, more specifically fecal coliforms, in
water is indicative of fecal pollution. In general, the presence of
fecal coliform organisms indicates recent and possibly dangerous
fecal contamination. When the fecal coliform count exceeds 2,000
per 100 ml there is a high correlation with increased numbers of
both pathogenic viruses and bacteria.
Many microorganisms, pathogenic to humans and animals, may be
carried in surface water, particularly that derived from effluent
sources which find their way into surface water from municipal and
industrial wastes. The diseases associated with bacteria include
bacillary and amoebic dysentery, Salmonella gastroenteritis, typhoid
and paratyphoid fevers, leptospirosis, chlorea, vibriosis and
infectious hepatitis. Recent studies have emphasized the value of
fecal coliform density in assessing the occurrence of Salmonella, a
common bacterial pathogen in surface water. Field studies involving
irrigation water, field drops and soils indicate that when the fecal
coliform density in stream waters exceeded 1,000 per 100 ml, the
occurrence of Salmonella was 53.5 percent.
Acidity and Alkalinity
Acidity and alkalinity are reciprocal terms. Acidity is produced by
substances that yield hydrogen ions upon hydrolysis and alkalinity
is produced by substances that yield hydroxyl ions. The terms
"total acidity" and "total alkalinity" are often used to express the
buffering capacity of a solution. Acidity in natural waters is
caused by carbon dioxide, mineral acids, weakly dissociated acids,
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and the salts of strong acids and weak bases. Alkalinity is caused
by strong bases and the salts of strong alkalies and weak acids.
The term pH is a logarithmic expression of the concentration of
hydrogen ions. At a pH of 7, the hydrogen and hydroxyl ion
concentrations are essentially equal and the water is neutral.
Lower pH values indicate acidity while higher values indicate
alkalinity. The relationship between pH and acidity or alkalinity
is not necessarily linear or direct.
Waters with a pH below 6.0 are corrosive to water works structures,
distribution lines, and household plumbing fixtures and can thus add
such constituents to drinking water as iron, copper, zinc, cadmium
and lead. The hydrogen ion concentration can affect the "taste" of
the water. At a low pH water tastes "sour". The bactericidal
effect of chlorine is weakened as the pH increases, and it is
advantageous to keep the pH close to 7. This is very significant
for providing safe drinking water.
Extremes of pH or rapid pH changes can exert stress conditions or
kill aquatic life outright. Dead fish, associated algal blooms, and
foul stenches are aesthetic liabilities of any waterway. Even
moderate changes from "acceptable" criteria limits of pH are
deleterious to some species. The relative toxicity to aquatic life
of many materials is increased by changes in the water pH.
Metalocyanide complexes can increase a thousand-fold in toxicity
with a drop of 1.5 pH units. The availability of many nutrient
substances varies with the alkalinity and acidity. Ammonia is more
lethal with a higher pH.
The lacrimal fluid of the human eye has a pH of approximately 7.0
and a deviation of 0.1 pH unit from the norm may result in eye
irritation for the swimmer. Appreciable irritation will cause
severe pain.
Rationale^fpreselection of Minor Parameters
Total Dissolved Solids (TDS) , '
The dissolved solids in waste water are mainly inorganic salts.
They are particularly important as they are relatively unaffected by
biological treatment processes and can accumulate in water
recirculation systems. Failure to remove them may lead to an
increase in the total solids content of ground waters and surface
water sources. The dissolved solids in discharge water, if not
controlled, may be harmful to vegetation and may also preclude use
in various irrigation practices. There is not sufficient data
available to establish effluent limitations for TDS, but at land
treatment systems TDS must be managed to ensure satisfactory
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performance without damage to the physical properties of the soil or
to the quality of the ground waters.
Ammonia Nitrogen and Other Nitrogen Forms
The three most common forms of nitrogen in wastes are organic,
ammonia and nitrate. Organic nitrogen will break down into ammonia,
nitrogen and nitrate. When ammonia nitrogen is present in effluent
waste water, it may be converted to nitrate nitrogen by oxidation.
When ammonia and nitrates are added to ponds and lakes, they
contribute to euthrophication. Additions of ammonia or urea as a
nutrient to nitrogen deficient waste is a common practice in the
industry.
Phosphates
Phosphorus, like nitrate, is linked directly to the eutrophication
process of lakes and streams. When applied to soil, phosphorus does
not exhibit a runoff potential because it is readily absorbed and
tenaciously bound on the surface of soil particles. In this case,
movement of phosphorus to ground water is essentially precluded and
water contamination can only occur if actual erosion of the soil
takes place. Phosphates may also be added as nutrients to
biological treatment systems.
Temperature
The temperature of effluent waste water is important, since release
of water at elevated temperatures into surface waters or ground
water formations could result in damage to the aquatic micro-
ecosystems. The design of treatment facilities is also dependent
upon the plant effluent temperature. Raw waste from many textile
mills is hot, but the temperature reduction occurs naturally in
waste treatment, and the temperature of the final effluent should be
very close to ambient. Therefore, effluent water temperature does
not present a problem.
Other Heavy Metals
Copper salts are still used in some dyeing operations of the textile
industry. Since they are harmful in biological systems, they should
be considered as pollutants. Zinc nitrate is widely used as a
catalyst for durable press goods, and small amounts will enter waste
systems. Magnesium chloride may be used in the same process.
Mercury was considered because of its known occurrence in raw
materials such as sodium hydroxide which is used in large amounts by
the textile industry. In normal operation, we would not expect the
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concentration of these materials in the waste water to exceed
harmful limits.
Toxic Organic Chemicals
Dieldrin, a moth proofing agent used for carpets would fall into
this grouping, but this chemical is no longer used. Carriers based
on chlorinated benzenes are considered toxic and care should be
exercised when they are used.
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SECTION VII
CONTROL AND TREATMENT TECHNOLOGY
The technology for control and treatment of waterborne pollutants in
the textile industry can be divided into two broad categories: in-
process and end-of-pipe. In-process control of waterborne
pollutants in turn depends upon two major conditions: (1) altering
the process requirements that generate water pollutants, and (2)
controlling water usage in nonprocess as well as process areas. For
example, pollutants can often be kept from entering waste water
streams through the institution of better housekeeping procedures,
containment of leaks and spills, good maintenance practices, and the
segregation and treatment of selected concentrated waste water
streams.
At present, the textile industry is concerned principally with end-
of-pipe treatment of its waste waters. However, the application of
waste water treatment technology has often been instituted without
detailed investigation of the alternatives to water and waste water
management within the process operations. This approach, of course,
is a. natural one to follow since institution of in-process changes
for an operating plant is frequently time consuming and expensive.
Furthermore, the incorporation of in-process control of waterborne
pollutants demands attention to specific operations which are often
proprietary whereas end-of-pipe waste water treatment technology is
based on generally similar principles which are available from
consultants, equipment manufacturers and the company's own
competitors.
The textile industry relies principally upon biological treatment of
its waste waters at the end-of-pipe. A large number of plants,
especially small ones, send waste waters into municipal sewage
systems where they may be a minor portion of the total flow;
however, in some instances the waste water flow to a municipal plant
is predominantly waste water from textile plants.
In-Process Control
Ancillary Process Control Technology. A big portion of the textile
waste loads is inherent in the methods of textile processing and
independent of the efficiency of the processing plants. For
example, size is applied to warp yarns to give them mechanical
strength in the weaving operations; all of this size must be taken
off before subsequent bleaching and dyeing. A finishing plant can
use variable amounts of water in removing this size, but the raw
waste load due to size is unchanged. The same applies to spinning
finishes on synthetic fibers, which are put on the yarn as a
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lubricant and to reduce static in the high-speed spinning and
textile operations. All of these "temporary" finishes must be
removed before dyeing of the yarn, so again the raw waste load is
almost independent of scouring efficiency.
On the other hand there are many unit operations which are dependent
on chemical concentrations to provide desired effects. The raw
waste loads of pollutants produced by these processes can be
substantially reduced through water reduction. A plant can also
reduce the other raw waste loads^-such as spills, reworks, etc.—in
many ways. These are considered below.
The principal axiom in reducing the waterborne pollutant loads
through control external to the process is to prevent pollutants
from entering the water streams. Although this seems obvious, its
successful application requires continual attention by operating
personnel. In fact, it is synonymous with creation of an effective
work safety program. In the textile industry, with its large number
of batch operations, one of the most important aspects of reducing
waterborne pollutants is to institute an effective water management
program—including expanded use of liquid-level-controls,flow
indicators and flow meters, adequate capacity for generating hot
water for wash operations, etc.—in conjunction with a good
maintenance program which will insure that leaks from valves, pipes,
pumps, etc., are promptly repaired so as to prevent process fluids
from entering floor drains, etc. Except for Subcategory 1 the
concentration levels of pollutants at the inlet to the waste water
treatment plants are not excessively high for industrial waste
waters. Consequently, a significant reduction in hydraulic capacity
should normally effectively lower the total emitted pollutants from
a given waste water treatment plant even if the concentration level
in the effluent rose moderately. Obviously, if process operations
can be changed to reduce the pollutant load to the waste water
treatment plant simultaneously with a reduction in hydraulic flow
the emitted pollutants will be reduced even more.
Procedures and methods for preventing spills and leaks should be the
paramount consideration, but passive systems for containment or pre-
venting their entry into water courses should be part of any control
plan. Only through assessment of the potential for pollutants to
enter water streams from accidental ocurrences and the development
of action plans is it possible to develop a high degree of assurance
that spilled liquids will be prevented from polluting water courses.
In summary, strict attention to housekeeping procedures and process
operation, can minimize abnormal waste loads.
Conventional Processing With Better Water Economy. The greatest
potential for improved water economy in the textile industry stems
from the use of better washing methods. About 80 percent of all the
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water used in textile wet processing is used for removing foreign
material—either that carried on the raw fiber, or materials
resulting from treating operations such as sizing, scouring, dyeing
and finishing. Furthermore, most applications of treating materials
are already carried out at low liquor ratio for the sake of material
and time economy. It follows that important water economies in
conventional processing can be made by reducing the amount of wash
water.
Water usage can be improved substantially as design engineers take
water economy into more active consideration. For example, so-
called "double laced" box washers have recently been introduced,
with claimed savings of up to 40 percent in a number of machines.
Significant water savings are claimed, but detailed quantitative
data are not available. More complex open-width washing machines
designed to induce greater turbulence, have been offered without
great success. Since the physical aim to be accomplished is clear,
i.e., breaking down an effective thick diffusion film in the fabric
interstices, it is likely that more efficient open-width machines
can be developed.
Rope washers generally are more effective than open-width washers
and may be susceptible to further improvement if back-mixing can be
controlled in a practical manner.
In addition to better washer design, there are opportunities for
water economy in more counter-current flows. A finishing plant
operator prefers to use fresh water at every machine, for ease of
control and adjustment, and for freedom from danger of cross-
contamination. However, some opportunities for counter-flow are
neither unduly difficult nor hazardous to quality. For example, it
is almost always acceptable to counter-flow water from machine to
machine where several machines are used in series at the same point
in the process. For example, it is common to use 5 or 6 or more
open-width box washers in series after scouring or mercerizing
operations, or two Tensitrol-type rope washers after scouring
operations. It is best for water economy to counter-flow the water
through the series. This is frequently but not universally
practiced today. Furthermore, it is practical to counter-flow water
from some later stages to some earlier stages. For example, white
washer effluent can almost certainly be used as feed water for
caustic washers. Additional opportunities for backflow of water
also exist. However, there are limitations; wash water from dyeing
operations, for example, always contains color, and is generally
unsuitable for re-use without cleanup. Caustic scour and desizing
wash waters are heavily laden with dissolved and suspended solids
and unsuitable for re-use.
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In principle, water cleanup could be used around particular machines
or groups of machines, thus extending water economy still further.
Preliminary consideration of investment and operating costs
indicates that this is generally less economical than pooling
effluents and operating one large treating plant. Closing of water
cycles around individual operations or groups of operations will
probably be limited to very special circumstances.
i:
In summary, further water economies can be achieved by machine
improvements and by wider use of countercurrent flow.
i
New Process Technology
Solvent Processing. Serious study of textile processing in organic
solvents dates back at least 15 years, although batch applications
of special finishing, such as water repellents has been practiced
for more than a generation. In the late 1950*5, Imperial Chemical
Industries pioneered a solvent system for continuous scouring of
cotton piece goods. Several large machines of this type have been
operated in the United States at various times since 1960. During
the 1960*s, a number of continuous solvent scouring and finishing
ranges were devised and tested in Europe. In most of these cases
the development work has been carried out by solvent suppliers or
equipment manufacturers.
In the course of this work it has become clear that chlorinated
solvents such as perchloroethylene and trichloroethylene are the
most advantageous materials now available. It has also become clear
that suitable machines can be manufactured and operated so as to
control air pollutions in the work space. Solvent loss remains an
economic problem. Extremely tight control is needed to keep solvent
loss per operation below 5 percent of fabric weight. To date, there
has been no appreciable commercial use of solvent finishing for
woven goods. However, solvent processing has established a firm, if
specialized, position in knit fabric finishing, especially in the
finishing of synthetic knits.
Solvent processing has found commercial use only where superior
fabric properties have been achieved. For example, solvent
applications of stain repellent finish to upholstery and drapery
materials are widely practiced. In this case, aqueous treatment is
not always possible, because the fabric is sensitive to water.
Similarly, solvent scouring and finishing of synthetic knit fabrics
is widely practiced because it is, in these cases, advantageous to
quality to avoid wetting with water. Some finishes, furthermore,
are not available in water soluble or dispersible form and can be
used only in solvents.
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On the other hand, very substantial research and development efforts
in the last decade or so have not led to replacement of aqueous
processing to any appreciable extent.
Adoption of a complete solvent processing scheme avoids the problem
of dealing with both aqueous and solvent wastes. As noted above,
however, a complete line of textile processing and finishing
compounds would first be required. Some thousands of different
dyestuffs and chemicals are now used in commt jial textile
processing. Only a limited number can be directly i nsferred to
solvent use.
On the grounds noted above, it is becoming clear that solvent
processing generally will be introduced only as superior results are
demonstrated. In general, this implies better properties in the
finished fabric, although processing advantages may lead the way in
a few cases. The prospects for solvent processing are outlined
below for each of several important finishing steps.
£ Scouring of Woven Fabric. Despite intense effort, solvent
scouring of woven fabrics has not established a firm place. The
properties of solvent scoured fabrics are not generally superior.
The wastes generated are the same with respect to organic content,
but, of course, free from the alkali generally used for aqueous
scouring.
Solvent Scouring of Knit Fabric. Solvent scouring of some synthetic
knit frabies is well established and growing. Commercial use is
based on superior results, fast drying and easy extension to
specialized solvent finishing. Contribution to water pollution
abatement is modest because scouring of knits does not contribute
very heavily to textile pollution loads.
Bleaching. It is possible to bleach from solvent sytems and large
scale demonstrations have been carried out. However, the process
used generates both aqueous and solvent wastes. No advantages have
been demonstrated with respect to fabric properties.
Dyeing. A very large effort has been devoted to solvent dyeing.
Some fibers are commercially dyed from solvent systems, notably
nylon sportswear and carpets by the STX beam dyeing process. The
advantages and limitations of solvent dyeing, both practical and
theoretical, were discussed at length in a January 1973 AATCC
Symposium. Collected papers, available from the American
Association of Textile Chemists and Colorists Research Triangle
Park, North Carolina, 27709, should be consulted for details.
Although many important textile fibers can be dyed from solvent
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systems, practical applications will apparently be limited to
special cases. There are not grounds for broad reliance on solvent
processing to solve current liquid effluent problems arising from
dyeing operations.
Solvent Finishing Woven,Goods. It has been shown that many
functional finishes can be applied from solvents. Some advantageous,
properties have been demonstrated, fcut no practical use has been
achieved. It is believed that advantages shown so far have been
insufficient to justify a changeover from the familiar aqueous
systems. In any event, chemical finishing is but a modest
contributor to textile effluents, since the aim is to capture a very
high fraction of the active agent on the cloth,
In special cases, i.e., water-sensitive fabrics, solvent finishing
has become fairly standard practice. Application of stain and soil
resistant finishes to upholstery fabrics is a typical example.
Solvent Finishing of Knit _ Fabric. Synthetic knit fabrics lend
themselves admirably to combination scouring and finishing from
solvents. Some modern finishes, such as silicone polymers for
single-knits, can be applied only from solvent. In other cases,
solvent processing recommends itself because of ease and speed of
drying, or because of superior properties developed by solvent
finishing. Although much of this development started with batch
operations in dry cleaning machinery, highly developed continuous
processing machines are now available from several manufacturers,
both domestic and foreign. It is clear that solvent processing of
knit fabrics is established and growing.
In summary, solvent processing is clearly finding a place in modern
textile processing. There are,, however, no grounds for supposing
that aqueous processing will be totally displaced by solvent '
processing.
Recovery and Re-use of Warp Size, Most woven goods require the use
of warp size during manufacture. The sizing, traditionally starch,
coats the warp yarns and binds the individual fibers together. This
action is necessary to preserve the warps from excessive abrasion
damage during weaving. The sizing is generally removed as the first
operation in the fabric finishing sequence. Warp size constitutes,
on the average, about 5 percent of the weight of the fabric, and it
all ends up in the effluent waters. Accordingly, it is a very
substantial contributor to the total BOD and COD in textile mill
effluents. Sizing waste accounts for about half the total BOD and
COD load from textile operations.
Since the advent of synthetic fibers, newer sizing agents have been
developed. A solubilized cellulose derivative, and polyvinyl
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alcohol have been widely used. At this time, PVA, alone or in
blends with starch, is the most popular size for the important
cotton/polyester blend fabrics.
While solvent sizing/desizing has a been suggested as a means of
reducing aqueous waste loads of BOD and COD, feasibility has not
been demonstrated. Organic solvents will contribute to both air and
water pollution load since recovery of solvents over 95X is almost
impossible. Water is also a solvent for demonstrated effective warp
sizes, such as polyvinyl alcohol or carboxy methyl cellulose (CMC).
Research now underway may eventually confirm the economic
practicality of recovering and reusing both the warp size (PVA or
CMC) and water. It is premature to state that solvent size/desize
will eventually find practical application.
Since the size is to be used repeatedly, some means to purge
impurities is mandatory. While this is a difficult problem, the
potential advantages of solvent size and desize are substantial.
Solvent size/desize will eventually find practical application. It
is likely that adoption of new sizing technology will be based on
demonstrated advantages over conventional methods rather than on
pollution control considerations alone.
Specific^In^Process^Changes
Wool Scouring. One of the problems in defining wool scour wastes
and in controlling the process for optimum performance is that
detergent is added on a fixed flow basis, and the demand for it
varies widely with the natural variations in the fleece as received.
Future effort may profitably be spent in developing a method to
measure the detergent demand and control its addition accordingly;
less detergent will be used, BOD load reduced and perhaps a more
easily separated emulsion will yield higher grease recoveries.
In addition, in the centrifuge recovery system described, rewashing
of the grit for recovery of up to 40 percent more grease than is
presently being recovered, appears possible with developmental
efforts. Furthermore, the value of centrifuge-recovered wool grease
is higher than that of acid-cracked grease (200 per pound in 1973).
Re—use of the waste treatment plant effluent as make-up water to the
scouring train may be feasible. One of the obvious problems is that
dissolved salts will build up.
solvent scouring has been used to remove the wool grease from the
wool. Jet fuel, benzene, carbon tetrachloride, ethyl alcohol,
methyl alcohol and isopropyl alcohol have been tried. The problems
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of flammability and explosive hazards, and of efficiency of solvent
recovery have prevented its use in the United States.
Solvent scouring requires subsequent detergent washing to remove the
dirt. More efficient methods of grease recovery using the water
scouring process appear capable of achieving grease recovery levels
comparable to that with solvent methods, and hence would probably
offer the better choice for further reducing pollution load in the
future.
Wool Finishing. Further effort should be extended to segregating
waste streams within the mill. In particular, many of the rinse
waters appear satisfactory for reuse both for subsequent initial
rinses and for pre-scouring steps and perhaps for fulling rinses.
Solvent scouring is practiced in several mills in place of initial
detergent scouring, to remove spin oils, sizes, and fugitive tints.
The savings in detergent costs appear to justify these systems,
resulting in a lower BOD load and somewhat lower water use.
Woven and Knit Fabric Finishing and Stock and Yarn Dyeing. The
possibilities for reducing water consumption in finishing woven
fabric were discussed earlier. In this section we will emphasize
pollutants other than water.
Scouring, mercerizing and bleaching generate substantial wastes,
particularly in textiles containing cotton. Large textile users
already recover spent caustic soda and this should be extended to
other users.
Better control of dyeing processes as a possible result of
automation could bring about reductions in dye and chemical usage as
well as in water.
Automation and instrumentation will reduce the amounts of auxiliary
chemicals essential for dyeing, e.g., salts; and sodium
hydrosulfite. Most mills have abandoned the use of chromates in
favor of peroxide and perborate. The use of pressure becks for
dyeing polyester is increasing, thus reducing carrier usage. Some
printing processes use solvent (Varsol) which can be recovered by
flotation and distillation.
Carpets. Continuous dyeing has been stated to use 20 to 25 percent
less the amount of water used in beck dyeing. Stock dyeing and
printing rinse also are similar lower level uses. However, a mill
can use a continuous process only if the volume of a given shade is
sufficiently high.
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If polyester becomes a major face-yarn material, there will be an
increase in raw waste load. This can be abated to some extent by
the use of pressure dye becks, as in subcategories 4 and 5, that
permit a reduction in the use of carriers and their attendant heavy
BOD load.
Commission Finishers - For those plants identified as commission
finishers in the above subcategories, the same process changes are
recommended. In addition, special attention to in-house management
and scheduling control, where possible, will bring additional
benefits and aid in pollutant control.
Biological Treatment_TechnQlogy
The treatment of waste effluents by biological methods is an
attractive alternative when a high proportion of the biodegradable
material is in the soluble form, as is the case in the textile
industry. These methods are applicable in this industry
irrespective of plant size, age or location.
Many types of microoganisms remove organic materials from liquid
wastes. Those most commonly used in treatment systems are
heterotrophs, which utilize organic carbon for their energy and
growth. Some are aerobic and require molecular oxygen for
converting wastes to carbon dioxide and water. Others are anaerobic
and grow without molecular oxygen. Anaerobic microorganisms grow
more slowly than aerobes and produce less sludge per unit of waste
treated than do aerobic microorganisms. Anaerobes also release
acids and methane, and their action on sulfur-containing wastes may
create odor problems. Some microorganisms are facultative; that is,
they can grow in either an aerobic or anaerobic environment.
The biological treatment of industrial wastes often lacks necessary
nutrients in the waste to sustain desirable biological growth.
Added nutrients, most often nitrogen and sometimes phosphorus, may
be required for efficient biological treatment of processing wastes.
Processing wastes generally require the addition of nitrogen before
successful biological treatment. Often this can be economically
accomplished by the addition of nutrient-rich wastes from another
source for combined treatment.
A discussion of the various methods of biological treatment is
presented in the following sections.
Activated Sludge:In this case the active biota are maintained as a
suspension in the waste liquid. Air, supplied to the system by
mechanical means, mixes the reaction medium and supplies the
microorganisms with the oxygen required for their metabolism. The
microorganisms grow and feed on the nutrients in the inflowing waste
waters. There are fundamental relationships between the growth of
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these microorganisms and the efficiency of the system to remove
BOD5.
A number of activated sludge systems have been designed, all of
which have their own individual configurations. Basically, these
designs consist of some type of pretreatment, usually primary
sedimentation and aeration, followed by sedimentation which will
allow the sludge produced to separate, leaving a clear effluent. ^
Portions of the settled sludge are recirculated and mixed with the
influent to the aeration section, usually at a proportion ranging
between 10 to 100 percent, depending upon the specific modification
to the basic activated sludge process.
The goal of these plants is to produce an actively oxidizing
microbial population which will also produce a dense "biofloc" with
excellent settling characteristics. Usually, optimization of floe
growth and overall removal is necessary since very active microbial
populations do not always form the best floes.
Activated sludge treatment plants are capable of removing 95 percent
or better of the influent BOD5 from textile manufacturing plants.
The extended aeration modification of the activated sludge process
is similar to the conventional activated sludge process, except that
the mixture of activated sludge and raw materials is maintained in
the aeration chamber for longer periods of time. The common
detention time in extended aeration is one to three days, rather
than six hours. During this prolonged contact between the sludge
and raw waste, there is ample time for organic matter to be adsorbed
by the sludge and also for the organisms to metabolize the organic
matter which has been built up into the protoplasm of the organism. '
Hence, in addition to high organic removals from the waste waters,
up to 75 percent of the organic matter of the microorganisms is
decomposed into stable products and consequently less sludge will '
have to be handled.
In extended aeration, as in the conventional activated sludge
process, it is necessary to have a final sedimentation tank. Some
of the solids resulting from extended aeration are finely divided
and therefore settle slowly, requiring a longer period of settling.
The long detention time in the extended aeration tank makes it
possible for nitrification to occur. If it is desirable for this to
occur, it is necessary to have sludge detention times in excess of
three days. This can be accomplished by regulating the amounts of
sludge recycled and wasted each day. Oxygen enriched gas could be
used in place of air in the aeration tanks to improve overall
performance. This would require that the aeration tank be
partitioned and covered, and that the air compressor and dispersion
system be replaced by a rotating sparger system, which costs less to
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buy and operate. When co-current, staged flow and recirculation of
gas back through the liquor is employed, between 90 and 95 percent
oxygen utilization is claimed.
Activated sludge in its varied forms is an attractive alternative in
textile waste treatment. Conventional design criteria are not
directly transferrable from municipal applications. However, high
levels of efficiency are possible at the design loadings normally
employed in treating other types of high strength organic wastes.
The general experience has been that biological solids separation
problems can be avoided if the dissolved oxygen concentration
remains above zero throughout the aeration basin, if management
minimizes very strong, concentrated waste releases, and if
sufficient amounts of nitrogen are available to maintain a critical
nitrogen: BODJ5 ratio. This ratio has been recommended to be 3 to 4
kg (Ib) N per 100 kg(lb) of BOD5 removed. Numerous cases have been
reported of successful combined treatment of textile and domestic
wastes by activated sludge and its modifications. Activated sludge
systems require less room than other high reduction biological
systems, but have higher equipment and operating costs. Properly
designed and operated systems can treat textile wastes to achieve
high BOD reductions.
Biological Filtration (Trickling Filter): The trickling filter
process has found application in treatment of many industrial
wastes. Very tall filters employing synthetic media, high
recirculation, and forced air circulation have been used to treat
strong wastes in the 300-4000 mg/1 BOD_5 range.
The purpose of the biofilter system is to change soluble organic
wastes into insoluble organic matter primarily in the form of
bacteria and other higher organisms. As the filter operates,
portions of the biological growth slough off and are discharged as
humus with the filter effluent. Usually, some physical removal
system is required to separate this insoluble organic material which
can be treated by other suitable methods, usually anaerobic
fermentation in a sludge digestor.
Trickling filters are usually constructed as circular beds of
varying depths containing crushed stone, slag, or similar hard
insoluble materials. Liquid wastes are distributed over this bed at
a constant rate and allowed to "trickle" over the filter stones.
Heavy biological growths develop on the surface of the filter
"media" throughout the depth of the filter and also within the
interstitial spaces.
The biological film contains bacteria, (Zooglea, Sphaerotilus, and
Beggiatoa); fungi (Fusarium, Geotrichum, Sepedonium); algae, both
green and blue-green (Phormidium, Ulothrix, Mononostrona); and a
very rich fauna of protozoa. A grazing fauna is also present on
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these beds consisting of both larval and adult forms of worms
(Oligochaeta), insects (Diptera and Coleoptera among others), and
spiders and mites (Arachnida).
A common problem with this type of filter is the presence of flies
which can become a severe nuisance. Insect prevention can usually
be achieved by chlorinating the influent or by periodically flooding
the filter.
Recirculation of waste water flows through biological treatment
units is often used to distribute the load of impurities imposed on
the unit and smooth out the applied flow rates. Trickling filter
BOD5 removal efficiency is affected by temperature and the
recirculation rate. Trickling filters perform better in warmer
weather than in colder weather. Recirculation of effluent increases
BOD5 removal efficiency, as well as keeping reaction-type rotary
distributers moving, the filter media moist, organic loadings
relatively constant, and increases contact time with the biologic
mass growing on the filter media.
Furthermore, recirculation improves distribution, equalizes
unloading, obstructs entry and egress of filter flies, freshens
incoming and applied waste waters, reduces the chilling of filters,
and reduces the variation in time of passage through the secondary
settling tank.
Trickling filter BOD5 removal efficiency is inversely proportional
to the BODJ5 surface loading rate; that is, the lower the BOD5
applied per surface area, the higher the removal efficiency.
Approximately 10-90 percent BOD reduction can be attained with
trickling filters.
Anaerobic Processes:Elevated temperatures (29° to 35°C or 85° to
95°F) and the high concentrations of organic material typically
found in industrial wastes make these wastes well suited to
anaerobic treatment. Anaerobic or facultative microorganisms, which
function in the absence of dissolved oxygen, break down the organic
wastes to intermediates such as organic acids and alcohols. Methane
bacteria then convert the intermediates primarily to carbon dioxide
and methane. Also, if sulfur compounds are present, hydrogen
sulfide may be generated. Anaerobic processes are economical
because they provide high overall removal of BOD5 and suspended
solids with no power cost (other than pumping) and with low land
requirements. Two types of anaerobic processes are possible:
anaerobic lagoons and anaerobic contact systems.
Anaerobic lagoons are used as the first step in secondary treatment
or as pretreatment prior to discharge to a municipal system.
Reductions of 85 percent in BOD5 and 85 percent in suspended solids
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can be achieved with these lagoons. A usual arrangement is two
anaerobic lagoons—relatively deep (3 to 5 meters, or about 10 to 17
feet), low surface-area systems with typical waste loadings of 240
to 320 kg BOD5/10CO cubic meters (15 to 20 Ib BOD5/1000 cubic feet)
and a detention time of several days.
Plastic covers of nylon-reinforced Hypalon, polyvinyl chloride, and
styrofoam can be used on occasion to retard heat loss, to ensure
4" anaerobic conditions, and hopefully to retain obnoxious odors.
Properly installed covers provide a convenient method for collection
of methane gas.
Influent waste water flow should be near, but not on, the bottom of
the lagoon. In some installations, sludge is recycled to ensure
adequate anaerobic seed for the influent. The outlet from the
lagoon should be located to prevent short-circuiting the flow and
carry-over of the scum layer.
Advantages of an anaerobic lagoon system are: initial low cost; ease
of operation; and the ability to handle shock waste loads and yet
continue to provide a consistent quality effluent. Disadvantages of
an anaerobic lagoon are odors although odors are not usually a
serious problem at well managed lagoons.
Anaerobic lagoons used as the first stage in secondary treatment are
usually followed by aerobic lagoons. Placing a small, mechanically
aerated lagoon between the anaerobic and aerobic lagoons is becoming
popular. It is currently popular to install extended aeration units
following the anaerobic lagoons to obtain nitrification.
The anaerobic contact system requires far more equipment for
operation than do anaerobic lagoons, and consequently is not as
• commonly used. The equipment, consists of equalization tanks,
digesters with mixing equipment, air or vacuum gas stripping units,
and sedimentation tanks (clarifiers). Overall reduction of 90 to 97
percent in BOD and suspended solids is achievable.
Equalized waste water flow is introduced into a mixed digester where
anaerobic decomposition takes place at a temperature of about 33° to
35°C (90° to 95°F). BOD5 loadings into the digester are between 2.4
and 3.2 kg/cubic meter (0.15 and 0.20 Ib/cubic foot), and the
detention time is between three and twelve hours. After gas
stripping, the digester effluent is clarified and sludge is recycled
at a rate of about one-third the raw waste influent rate. Sludge at
the rate of about 2 percent of the raw waste volume is removed from
the system.
Advantages of the anaerobic contact system are: high organic waste
load reduction in a relatively short time; production and collection
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of methane gas that can be used to maintain a high temperature in
the digester and also to provide auxiliary heat and power; good
effluent stability to waste load shocks; and application in areas
where anaerobic lagoons cannot be used because of odor or soil
conditions. Disadvantages of anaerobic contractors are high initial
and maintenance costs and some odors emitted from the clarifiers.
Anaerobic contact systems are usually used as the first stage of
secondary treatment and can be followed by the same systems that
follow anaerobic lagoons or trickling filter roughing systems.
Other^ Aerobic Processes; Aerated lagoons have been used successfully
for many years in a number of installations for treating industrial
wastes. However, with recent tightening of effluent limitations and
because of the additional treatment aerated lagoons can provide, the
number of installations is increasing.
Aerated lagoons use either fixed mechanical turbine-type aerators,
floating propeller-type aerators, or a diffused air system for
supplying oxygen to the waste water. The lagoons usually are 2.4 to
4.6 m (8 to 15 feet) deep, and have a detention time of two to ten
days. BOD5 reductions range from 40 to 60 percent with little or no
reduction in suspended solids. Because of this, aerated lagoons
approach conditions similar to extended aeration without sludge
recycle.
Advantages of this system are that it can rapidly add dissolved
oxygen (DO) to convert anaerobic waste waters to an aerobic state;
provide additional BOD5 reduction; and require a relatively small
amount of land. Disadvantages are the power requirements and that
the aerated lagoon, in itself, usually does not reduce BOD5 and
suspended solids adequately to be used as the final stage in a high
performance secondary system. Aerated lagoons are usually a single
stage of secondary treatment and should be followed by an aerobic
(shallow) lagoon to capture suspended solids and to provide
additional treatment.
Aerobic lagoons (or stabilization lagoons or oxidation ponds), are
large surface area, shallow lagoons, usually 1 to 2.3 m deep (3 to 8
feet) , loaded at a BOD5_ rate of 22-56 kilograms per hectare (20 to
50 pounds per acre) . Detention times will vary from several days to
six or seven months; thus aerobic lagoons require large areas of
land.
Aerobic lagoons serve three main functions in waste reduction:
1. Allow solids to settle out.
2. Equalize and control flow.
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3. Permit stabilization of organic matter by aerobic and
facultative microorganisms and also by algae.
Actually, if the pond is quite deep, 1.8 to 2.U m (6 to 8 feet), so
that the waste water near the bottom is void of dissolved oxygen,
anaerobic organisms may be present. Therefore, settled solids can
be decomposed into inert and soluble organic matter by aerobic,
anaerobic or facultative organisms, depending upon the lagoon
conditions. The soluble organic matter is also decomposed by
microorganisms causing the most complete oxidation. Wind action
assists in carrying the upper layer of liquid (aerated by air-water
interface and photosynthesis) down into the deeper portions. The
anaerobic decomposition generally occurring in the bottom converts
solids to liquid organics which can become nutrients for the aerobic
organisms in the upper zone.
Algae growth is common in aerobic lagoons; this currently is a
drawback when aerobic lagoons are used for final treatment. Algae
may escape into the receiving waters, and algae added to receiving
waters are considered a pollutant. Algae in the lagoon, however,
play an important role in stabilization. They use CO2, sulfates,
nitrates, phosphates, water and sunlight to synthesize their own
organic cellular matter and give off free oxygen. The oxygen may
then be used by other microorganisms for their metabolic processes.
However, when algae die they release their organic matter in the
lagoon, causing a secondary loading. Ammonia disappears without the
appearance of an equivalent amount of nitrite and nitrate in aerobic
lagoons. From this, and the fact that aerobic lagoons tend to
become anaerobic near the bottom, it appears that some
denitrification is occurring.
High winds can develop a strong wave action that can damage dikes;
Riprap, segmented lagoons, and finger dikes are used to prevent wave
damage. Finger dikes, when arranged appropriately, also prevent
short circuiting of the waste water through the lagoon. Rodent and
weed control, and dike maintenance are all essential for good
operation of the lagoons.
Advantages of aerobic lagoons are that they reduce suspended solids,
oxidize organic matter, permit flow control and waste water storage.
Disadvantages are the large land required, the algae growth problem,
and odor problems.
Aerobic lagoons usually are the last stage in secondary treatment
and frequently follow anaerobic or aerated lagoons. Large aerobic
lagoons allow plants to store waste water discharges during periods
of high flow in the receiving body of water or to store for
irrigation during the summer. These lagoons are particularly
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popular in rural areas where land is available and relatively
inexpensive.
Rotating Biological Contactor; The rotating biological contactor
(RBC) consists of a series of~closely spaced flat parallel disks
which are rotated while partially immersed in the waste waters being
treated. A biological growth covering the surface of the disk
adsorbs dissolved organic matter present in the waste water. As the
biomass on the disk builds up, excess slime is sloughed off
periodically and is removed in sedimentation tanks. The rotation of
the disk carries a thin film of waste water into the air where it
absorbs the oxygen necessary for the aerobic biological activity of
the biomass. The disk rotation also promotes thorough mixing and
contact between the biomass and the waste waters. In many ways the
RBC system is a compact version of a trickling filter. In the
trickling filter the waste waters flow over the media and thus over
the microbial flora; in the RBC system, the flora is passed through
the waste water.
The system can be staged to enhance overall waste water reduction.
Organisms on the disks selectively develop in each stage and are
thus particularly adapted to the composition of the waste in that
stage. The first couple of stages might be used for removal of
dissolved organic matter, while the latter stages might be adapted
to other constituents, such as nutrient removal.
The major advantages of the RBC system are its relatively low
installed cost, the effect of staging to obtain dissolved organic
matter reductions, and its good resistance to hydraulic shock loads.
Disadvantages are that the system should be housed to maintain high
removal efficiencies and to control odors. Although this system has
demonstrated its durability and reliability when used on domestic
wastes, it has not yet been fully tested to treat textile processing
wastes.
Rotating biological contactors could be used for the entire aerobic
secondary system. The number of stages required depend on the
desired degree of treatment and the influent strength. Typical
applications of the rotating biological contactor, however, may be
for polishing the effluent from anaerobic processes and from
roughing trickling filters and as pretreatment prior to discharging
wastes to a municipal system. A BOD5 reduction of over 90 percent
is achievable with a multi-stage RBC.
Performance of Biolocjical Treatment Systems
Evaluation of data obtained from the textile waste water treatment
plants surveyed indicate that the operational mode for exemplary
biological systems is extended aeration. No exemplary plant has an
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average residence time in the aeration basin of less than 17 hours.
Eighteen exemplary biological systems with an average BOD removal
efficiency of greater than 95 percent are listed in Table 20. The
complete treatment scheme for most exemplary waste treatment plants
includes screening and extended aeration followed by clarification
and polishing lagoons.
Removal of fibers from the waste water prior to their entering the
aeration basin is often necessary to prevent floating scum from
building on the surface of the basin or to prevent the aeration
equipment from malfunctioning and reducing oxidation efficiency.
Usually, these fibers are removed satisfactorily through the use of
bars or screens.
Removal of BOD5_ and suspended solids from textile waste water is
accomplished most satisfactorily through the employment of extended
aeration including clarification and sludge return. Textile waste
water usually contains ample phosphates which are available as
nutrients for the microorganism of the biological system. Nitrogen
in the form of ammonia or nitrate may be required in some cases in
which this nutrient deficiency has been identified.
Suspended solids are removed from biologically-treated waste water
by gravity sedimentation. The concentrated slurries are recycled to
aeration basins while the overflow from the clarifier goes to
lagoons for further polishing or discharge to the receiving stream.
Because of colloidal particulates from certain operations, chemical
coagulation may be required prior to biological treatment. This
operation is usually carried out by the addition of coagulating
chemicals and/or the use of coagulant aids to improve
sedimentation. In general, the clarifiers used in the textile
industry are designed for overflow rates considerably less than
those usually found in municipal systems.
Excluding the high BODS values for wool scouring-subcategory 1, the
average BODS concentration of the exemplary treatment is about 20
mg/1, running from a low of 2 to a high of 83 mg/1. Of this group
approximately 20 percent exceeded 30 mg/1.
In effect, many of the waste water treatment plants are being
operated as a two-stage biological system since polishing lagoons of
various residence times may follow the aerated basin.
Chemical oxygen demand (COD) is measured less frequently than BOD5.
As in the case of BODS, the COD of wool scouring waste is greater
than that of waste waters from other categories, both on a
concentration basis. Exclusive of the wool scouring waste, the
industry's average COD for the plants surveyed is 222 mg/^. with a
low value of 68 mg/1 and a high of 427 mg/1. The ratio of COD to
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BODS increases significantly across the waste water treatment
plants, which indicates the refractory nature of some of the
components of the waste waters. Although COD is probably a better
measure of the pollutant level of waste waters, other parameters
such as total organic carbon (TOC) or total oxygen demand (TOD)
might be even more indicative.
Although the ratio of COD to EOD is generally recognized as an
indicator of the biologically refractory nature of waste water
pollutants, the variability in this ratio is affected by many
factors. One is the capabilities of a specific biological system to
degrade carbonaceous substances. For example, PVA, one of the most
extensively used sizes in the textile industry, has been considered
to be essentially refractory in terms of its loading on an activated
sludge plant, 1 percent BOD, whereas the theoretical oxygen demand
is 36 percent. This would indicate that only 3 percent of the PVA
is normally attacked in a five-day BOD test, or loosely speaking, 97
percent of it would pass unaffected through an activated sludge
plant. However, 'recent data shows that this is not the case; in
some activated sludge plants where the organisms have become
acclimated to the PVA, substantial PVA reduction is achieved.
Textile process operations often require high-temperature water,
however, heat reclamation is also widely practiced as a matter of
economics so the waste waters sent to the treatment plants usually
do not present any significant thermal shock problems. Furthermore,
the long residence time generally found in the waste water treatment
systems serves effectively to prevent rapid changes in temperature.
The most important temperature effect is not expected to be high
temperatures, but low temperatures. In northern areas, the low
wintertime temperatures in biological treatment systems will reduce
the biological activity and thus the efficiency of BOD5 removal.
Color in the waste waters of the textile industry is inherent in the
nature of the operations. Since color chemicals are specifically
formulated for resistance to degradation under the oxidizing
conditions of the world, it is not surprising that removal of color
in aerobic biological systems is erratic. Although color
concentration normally is reduced somewhat in the biological systems
surveyed, data obtained were in arbitrary units, most often APHA(Y)
standard. color removal efficiency is known to be highly specific
to the individual plant and the particular processes being operated
at a given time. Although a number of research and development
projects have been carried out, there is no one generally accepted
method for color removal. Use of adsorptive technology—such as
flocculation and activated carbons—and anaerobic treatment appear
to offer the best possibility for removing color.
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Chromium is the most significant heavy metal of concern in the
textile industry although others are employed selectively. Phenol
and sulfides have been identified as pollution parameters which may
be present in the textile waste stream, associated with some of the
processes used in textile manufacture. There is good evidence that
at low levels of chromium, phenol and sulfides in the raw waste an
activated sludge treatment plant removes a substantial portion.
Pollution experts within the textile industry have noted that
chromium, phenol and sulfide removal across a waste treatment plant
is proportional to the amount of BOD removed (more specifically the
excess sludge removed) and is inversely proportional to the amount
of suspended solids carried over in the final effluent from the
secondary clarifier. Proper removal of chrome, phenol and sulfide
is dependent on proper removal of suspended solids.
gther^Constituents: Wastewaters from ancillary operations such as
cooling towers, steam generating facilities and water treatment
plants may be significant factors in the waste water volumes emitted
from the textile industry. In those instances where one must handle
cooling tower and boiler blowdowns that contain corrosion inhibiting
chemicals, algacides and biocides, the technology for selective
removal is usually available. Of course, the best practicable
control technology currently available for process waste waters will
not remove soluble inorganic salts which predominate in these
blowdowns. Toxic and hazardous substances in these systems can be
controlled either by eliminating them, replacing them with less
toxic, less hazardous substances or treating isolated streams to
remove them. Selection of a course of action to cope with toxic and
hazardous materials in these blowdowns is more a question of
economics than a question of technology.
Reliability, operability and consistency of operation of the waste
water treatment processes found to be most frequently used in the
textile industry can be high if appropriate designs and operational
techniques are employed. The end-of-pipe treatment utilizing
extended aeration biological systems is a well established
technology that requires attention to a limited number of variables
to ensure a high degree of reliability. Although many variables can
affect the operability of a biological system, in general the best
overall performance is achieved when the highest consistency of flow
and waste water composition occurs.
Since the textile industry is predominantly a batch type process
operation rather than continuous, it follows that both flow rates
and waste water composition will vary significantly. That the
industry recognizes this variability is apparent from the nature of
the waste water treatment systems, i.e., long residence time systems
which hold sufficient volumes so that high instantaneous flow rates
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or high concentrations can be rapidly equalized to prevent shock
loading of the biological system.
The most important operational aspects of these extended aeration
systems are equipment reliability and attention to operating detail
and maintenance. Spare aeration equipment (usually floating surface
aerators) improves the possibility of consistent operation; however,
many treatment systems have an adequate overcapacity already
installed as insurance against the results of equipment failure. It
is desirable to install spare equipment at critical points, for
example, sludge return pumps. Perhaps of equal importance is a
design that permits rapid and easy maintenance of malfunctioning
equipment.
Therefore, control of the biological treatment plant and the
consistency of the results obtained are largely a matter of
conscientious adherence to well-known operational and maintenance
procedures. Automatic control of biological treatment plants is far
from a practical point. Although in-line instrumentation for
measurement of pH, dissolved oxygen, temperature, turbidity and so
on, can improve the effectiveness of operation, its use is minimal
in the textile industry's existing waste water treatment plants.
Nevertheless, no practical in-line instrumentation can replace the
judicious attention to operational details of a conscientious crew
of operators.
An activated sludge system which is permitted to operate at a
constant F:M ratio all year round and with minimum operational
changes would have a natural variation as shown in Section IX by the
solid line in Figure 19. A similar system with careful operational
control would have a controlled monthly average variation as shown
by the points. Although the mean value is the same, the amount of
natural variation is controlled by the operator through aeration
rate control, sludge recycling and F:M ratio adjustments. These
adjustments can be made daily so that monthly averages can be held
within the desired limits.
A well-operated and properly designed facility can be controlled
within +25 percent of the average on a monthly operating basis. A
system with minimal operational control, or an allowance of +50
percent of the averages on a monthly basis, has been used to
calculate the maximum monthly effluent limitation.
ADVANCED WASTE WATER TREATMENT TECHNOLOGY
In all categories of textile plants, it is assumed that good
secondary treatment will have a high quality effluent as
demonstrated by the exemplary plants. The definition of advanced
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treatment systems is therefore confined to tertiary treatment of the
secondary effluents, dewatering and incineration of sludges, and
possibly to preconditioning of some specialized waste streams to
render them compatible with the advanced waste treatment process.
In some cases, advanced treatment systems have been tried out on
textile wastes and their effectiveness in dealing with these various
pollutant parameters has been assessed. In other cases it is
necessary to predict their usefulness to the textile industry from
experience with other similar waste streams or by an understanding
of the physico-chemical principles involved.
The processes under consideration have been grouped according to the
overall chemical or physical mechanism of their operation:
1. phase change
2. physical separation
3. sorption systems
4. chemical clarification
Phase Change
Distillation: The multistage flash (MSF) process consists
essentially of pumping hot salt, brackish, or contaminated water
through suitable nozzles into a chamber in which the temperature and
pressure are lower than that of the water itself. Part of the water
flashes off instantly as steam which passes through demisters to
remove entrained droplets of impurities and condenses on tubing
cooled by entering feed water. The distilled water drops off the
tubes into a trough and is collected as the product water.
In order to improve the efficiency of the process and recover most
of the heat energy a multi-stage system is preferred in which the
latent heat from the condensation of the steam produced in the
evaporation chamber is used to preheat the cooler feed water flowing
in the condenser tubes counter current to the brine in the flash
chambers. Thus, the chief thermal energy requirement is that needed
to raise the feed water from ambient temperatures to the temperature
of the outgoing brine. Recirculation of the brine improves thermal
efficiency considerably and all modern MSF plants are of this
design.
Two types of feed water treatment are generally employed to reduce
scale formation. Frequently a proprietary material is used,
containing a polyphosphate or polyelectrolyte as the active
ingredient. These compounds do not prevent scale from forming but
rather modify its character so that it may be easily washed out or
dissolved by weak acids periodically. Often acid treatment is used.
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with sulfuric acid generally preferred. The acid is added
continuously to the feed water in small amounts to reduce the pH
below 7 and decompose the carbonate compounds that cause hard
scaling in the tubes and flash chambers. In many of the units using
acid, the carbon dioxide released by the acid is removed in a
separate decarbonator placed in the feed water circuit after the
reject stages. Otherwise the carbon dioxide is removed with the
other dissolved gases by the steam jet deaerator. In modern units
steam jet deaerators are used to deaerate the flash chambers and to
produce a vacuum.
The vertical tube evaporator (VTE) is a long-tube vertical
distillation type of desalting plant.
In the climbing-film vertical evaporator, the most common design,
the brine is maintained at a predetermined level inside the vertical
tubes. These tubes are heated externally by the incoming steam in
the first effect or by the hot product vapors in subsequent effects.
This is in direct contrast to a submerged tube type of unit which
has the steam inside and the boiling brine outside the tubes. The
vapors from the boiling brine rise in the vertical tubes into a
vapor chamber and are led from there into the vertical tube heat
exchanger in the next effect where the heat is given up to the brine
circulating in these tubes.
The resulting fresh water condensed on the outside of the tubes is
removed and combined with product from the subsequent effects. The
combined product is cooled in a final condenser with feed water.
The incoming feed water is fed into the first effect and the
concentrated brine flows in the same direction as the vapors. The
brine in each effect circulates either by natural temperature
differences or by forced circulation.
In another modification, known as the thermal recompression
evaporator, part of the vapors from the last effect are entrained
and compressed by expanded live steam from the boiler. The
resulting mixture becomes the heating medium for the first effect.
This scheme is particularly advantageous where high-pressure steam
is available as a source of heat and it can be used in conjunction
with a single or multiple effect vertical-tube evaporator.
Relevance to Textile Waste Treatment. The waste waters from the
textile industry may have a moderately high concentration of organic
chemicals in comparison with the concentrations in brackish or
saline waters.
In some instances, it might be necessary to treat waste water by
activated carbon adsorption to insure adequate removal of organic
species. Therefore, a thorough consideration of the entire process
chemistry will be required before one can determine whether
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•evaporation can be successfully applied to waste waters containing
carbonaceous substances. If the waste water streams contain very
low concentrations of organics and high concentrations of dissolved
inorganic salts, the applicability of evaporation is more readily
predicted, being essentially an evaluation of economics.
Freezing Techniques: It has long been recognized that individual ice
crystals formed in chilled impure water are composed of pure water.
Much effort has therefore gone toward the development of practical
processes to take advantage of this phenomenon for the desalination
or purification of water. Attention is presently centered on two
types of equipment.
The vacuum freeze vapor compression (VFVC) system has the longest
history. In this type of device, feed water is chilled and exposed
to a slight vacuum. Some of the water vaporizes and the resulting
loss of heat of vaporization causes ice crystals to form in the
system.
The ice crystals are separated mechanically from the brine by means
of sieves and scrapers and transferred to melting chambers. At the
same time the water vapor formed during the boiling-freezing stage
is compressed and introduced also to the melting chamber, where it
condenses on the ice crystals. In practice the system is more
complicated, with particular care being required to wash the ice
crystals free from feed water and to maintain the correct
temperatures and pressures throughout.
The second type of design employs as the vaporizing constituent a
secondary refrigerant which is insoluble in water. Usually, liquid
butane under pressure is bubbled through the feed water, vaporizing,
expanding and causing ice crystals to form. As in the vacuum freeze
system, the crystals are then separated mechanically and washed by
liquid butane. The secondary refrigerant system has the advantage
that the equipment operates at higher pressures and smaller volumes
of gas (butane), resulting in less expensive and more reliable pumps
and compressors.
Relevance to Textile Waste Treatment. A few small VFVC plants have
been erected in this "country and abroad for desalination of
seawater, but have not had enough service to develop useful
histories.
Their principal advantage appears to be that they are relatively
insensitive to the nature of the chemicals in the feed water and,
because they operate at low temperatures, resist the scaling and
corrosion problems which plague most other types of plants. None
has been used for waste water treatment. The secondary refrigerant
system is still in the pilot plant stage of development.
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Although neither type of freezing plant has been used in the textile
industry for waste water treatment, it might be attractive because
of its tolerance of high levels of salts, organics, suspended solids
and other materials in the feed water. It can be operated at brine-
to- product ratios as low as about 0.02, and brine concentrations as
high as 60,000 mg/1 TDS. This, of course, considerably reduces the
cost of ultimate brine evaporation or disposal.
Physical^Separation
Filtration:
The removal of suspended solids or colloidal material from water by
filtration is accomplished by one of a number of mechanisms which
may be generally classified as straining or transport attachment.
Straining is the elimination of particulate matter by size
discrimination; that is, a particle of greater diameter than a pore
opening will be physically restrained from passage.
Transport - Attachment refers to a two step principle and is applied
to particulate matter which may be much smaller than the pore size.
The particles are transported across the stream lines to the
proximity of the filter medium where attachment forces predominate.
Filtration is the most common form of advanced waste water treatment
practiced today. This is due to its relatively inexpensive nature
and its effectiveness in removing suspended solids and the organics
associated with those solids. It provides excellent preparation of
waste for application of other advanced waste treatment techniques
and is an.integral part in many designs of these systems.
Relevance to Textile Waste_Treatment. Rapid sand type filters have
had considerable use in waste treatment systems for direct
filtration of secondary effluent.
Early work on filtration of secondary effluent took place in Europe.
Truesdale and Birkbeck reported on tests run between October, 1949,
and May 1950, at the Luton Sewage Works. Beds of sand 2 feet deep,
ranging in size from 0.9 mm to 1.7 mm, exhibited 72 to 91 percent
removal of suspended solids and 52 to 70 percent removal of BOD.
Flow rates ranged from 1.33 to 3.3 IMP.gal/min/sq.ft.
Naylor, Evans and Dunscome later reviewed 15 years of studies of
tertiary treatment at Luton. A 3-foot deep bed of 10 to 18 mesh
sand consistently provided an effluent of U to 6 mg/1 suspended
solids at flow rates of 3.3 Imp.gal/min/sq.ft.
In the U. S., most direct filtration work has been with activated
sludge effluent. At the Hyperion Plant in Los Angeles, sand of 0.95
mm effective size was used in a shallow bed (11 inches deep)
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traveling backwash filter. This study lasted for six months during
which time 46 percent suspended solids removal and 57 percent BOD
removal were obtained. Filtration rate was 2 gal/min/sq.ft.
Difficulty was encountered in cleaning the filters and performance
gradually deteriorated during the study. Use of a finer sand (0.45
mm effective size) in an attempt to yield a better effluent was a
failure due to very rapid clogging of the filter.
0 Much greater success utilizing the traveling backwash filter for
activated sludge effluent treatment was obtained by Lynam in
Chicago, The effective size of sand used in this study was 0.58 mm.
Suspended solids removal of 70 percent and BOD removal of 80 percent
were obtained at flow rates of 2 to 6 gal/min/sq.ft. Terminal
headless was quite low (11 inches of water.) The range of flows
studied exhibited no significant difference in terms of suspended
solids removal.
Gulp and Gulp reviewed the work on plain filtration of secondary
effluent with both single medium and multi-media filters. They
concluded that, with either type of filter, better results would be
obtained as the degree of self flocculation of the sludge increased.
Thus, a high-rate activated sludge effluent which contains much
colloidal material should filter poorly, while an extended aeration
effluent should filter well. Multi-media filters exhibit a marked
superiority for filtration of activated sludge effluent because of
the high volume of floe storage available in the upper bed and the
polishing effect of the small media. They indicated the expected
performance of multi-media filters for plain filtration of secondary
effluents as shown in Table 9.
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Table 9
EXPECTED EFFLUENT SUSPENDED SOLIDS FROM MULTI-MEDIA
FILTRATION OF BIOLOGICAL EFFLUENTS
Biological System Effluent TSS
(mg/1)
High Rate Trickling 10 - 20
2 - Stage Trickling Filter 6-15
Contact Stabilization 6-15
Conventional Activated Sludge 3-10
Extended Aeration 1-5
The application of filtration to biologically treated effluent is
dependent on the nature of the biological system and the biological
solids produced by that system rather than the nature or
characteristics of the raw waste. That is, application of
filtration to secondary effluent from textile wastes will remove the
biological solids the same as it would remove the biological solids
generated from other wastes.
Reverse Osmosis. Reverse osmosis for desalinization of sea water
and brackish water has been under extensive investigation since the
discovery in the early 1960's of high flux membranes capable of re-
jecting salts. Much of the research and development work was made
with a view toward recovering potable water from sea water.
Although this aim still has not been fully attained at prices
competitive with other processes such as flash distillation,
improved technology arising from these programs and increased com-
mercial interest has resulted in some successful utilization of
reverse osmosis for removal of dissolved salts from industrial waste
streams.
The process of reverse osmosis relies upon the ability of certain
specialized polymeric membranes, usually cellulose acetate or nylon
to pass pure water at fairly high rates and to reject salts. And to
do this saline feed streams are passed at high pressures over the
surfaces of the membranes. The applied hydraulic pressures must be
high enough to overcome the osmotic pressure of the saline feed
stream, and to provide a pressure driving force for water to flow
from the saline compartment through the membrane into the fresh
water compartment.
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In a typical reverse osmosis system, feedwater is pumped through a
pretreatment section which removes suspended solids and, if
necessary, ions such as iron and magnesium which may foul the
system. The feedwater is then pressurized and sent through the
reverse osmosis modules. Fresh water permeates through the membrane
under the pressure driving force, emerging at atmospheric pressure.
The pressure of the concentrated brine discharge stream is reduced
by a power recovery turbine, which helps drive the high pressure
pump, and then is discharged.
Three types of reverse osmosis configurations are currently popular.
The first, known as the "spiral wound" configuration, uses flatsheet
cellulose acetate membranes wound in a spiral to produce a multitude
of thin channels through which the feed water flows under high
laminar shear. This configuration is inexpensive, produces high
water fluxes, and consequently efficient use of membrane area. Its
major difficulty is that the resulting thin channels become easily
fouled and plugged, so a process stream must have a very low level
of suspended solids.
The second configuration uses tubular cellulose acetate membranes to
bring about turbulent flow and overcome concentration polarization.
The membrane is formed into a tube—with an inside diameter of about
1 inch, and the "active11 (salt rejecting) face of the membrane on
the inside of the tube—through which the feed stream is
recirculated at high turbulent speeds. Membrane utilization is not
as efficient as in the spiral wound configuration, but there is less
trouble with flow distribution, fouling and plugging. This system
can handle highly contaminated wastes with high concentrations of
suspended solids.
Finally, a reverse osmosis system using a multitude of hollow nylon
fibers has shown considerable utility on commercial waste streams.
A bundle of fibers, with the "active" side of the nylon membranes on
the exterior of the fibers, is encased in a module. Feed water is
passed at high velocities between the fibers, and fresh product
water permeates into the interior lumens of the fibers from where it
is collected. This configuration results in rather low utilization
of membrane area, but since the cost per unit area of the membranes
is considerably lower than the cost of the cellulose acetate
membranes, the ultimate cost of water recovery is competitive for
low salinity feed streams. This configuration, like the spiral
wound one, is highly susceptible to fouling by suspended solids, and
requires thorough pre-treatment of the feed stream.
Relevance to Textile Wastes Treatment^ The major application of re-
verse osmosis to textile wastes would appear to be in removal of
salt from secondary sewage plant effluent. The technology appears
adequate to reduce the effluent salts to potable levels (less than
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200 mg/1). The process should also result in excellent color
removal, and substantial removal of residual BOD and COD. The major
limitation appears to be cost: for large plants, 19,000 cu tn/day (5
mgd) or greater, costs are 13 to 190/1000 liters (50 to 750/1000
gallons)* However, the costs increase greatly for smaller plants
because of greater labor costs.
The major technical limitation of the process for treatment of
secondary effluent is the requirement of feed stream quality. High
levels of suspended solids greatly reduce water flux rates through
the membranes, and increase costs substantially. It will therefore
be necessary to remove the suspended solids from the feed. Grease
and oil in the feed may also retard fluxes to some degree, although
this effect reportedly is not as great in the tubular
configurations.
In addition to treatment of secondary sewage effluent, reverse
osmosis has been considered for a number of other applications in
textile wastes. An experimental hollow-fiber reverse-osmosis pilot
plant operates on the total waste stream from a textile plant. This
system, which has allowed SOS recovery of the product water, with
good color removal. Data on flux rates, cost, or longevity are
inadequate to extrapolate to the ultimate utility of the process.
It is expected that flux decline, because of suspended solids, may
be a problem, and COD may not be removed adequately.
Another potential application of reverse osmosis is recovery of
sizing materials. Carboxymethylcellulose (CMC) and polyvinylalcohol
(PVA) will both be retained at great efficiency by reverse osmosis,
allowing these sizing materials to be concentrated for reuse. The
savings from reuse of these sizing streams may offset the costs of
the smaller plants required to process just the sizing waste
streams.
Ultrafiltratign^ Ultrafiltration is similar to reverse osmosis in
that it relies on the permeation of water through a semipermeable
membrane under a hydraulic driving pressure. The distinction
between reverse osmosis and ultrafiltration lies primarily in the
retention properties of the membranes: reverse osmosis membranes
retain all solutes, including salts, while ultrafiltration membranes
retain only macromolecules and suspended solids. Thus salts,
solvents, and low molecular weight organic solutes pass through
ultrafiltration membranes with the permeant water. Since salts are
not retained by the membrane, the osmotic pressure differences
across ultrafiltration membranes are negligible. Flux rates through
the membranes usually are fairly high, and hence lower pressures can
be used than are practical in reverse osmosis. Typical pressure
driving forces for ultrafiltration are 20 to 100 psi.
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Membranes may be made from cellulose acetate, polyelectrolyte
complexes, nylon, or a variety of inert polymers. Hence, highly
acidic or caustic streams may be processed, and the process is not
usually limited by chemical attack of the membranes.
Relevance to Textile Waste Treatment . Since ultraf iltration does
not remove salts and low molecular weight organic compounds such as
dissolved dyes, its utility in textile waste treatment would appear
to be limited to macromolecules and suspended solids.
Concentration and recovery of disperse dyes by ultrafiltration may
be feasible, where a single color is in the waste stream.
Concentration of polymeric cotton sizing materials (PVA and CMC) is
technically feasible since the UF membranes will retain the polymers
and pass the polymer-free water at reasonable fluxes. An
experimental system is being used to test the feasibility of PVA
concentration by ultrafiltration, with the ultimate aim of re-using
the sizing polymer. The membrane in this system is a new
experimental "dynamically formed" membrane based on deposition of
organic surfactants on porous carbon, but the process should be
feasible on more conventional UF membranes at a cost of 132 to 26 £
per 1000 liters (502 to $1.00 per thousand gallons) of water
removed.
Electrodialysis: The production of potable water from brackish
waters by electrodialysis is a mature desalting process.
Economically, the process is usually limited to feed waters having
total dissolved solids up to 10,000 mg/1 and more commonly it treats
waters with 1000 to 2000 mg/1 solids. It is not practical to reduce
the total solids in the produce water to a few mg/1 as is done in
distillation plants; about 200 mg/1 is the highest purity attainable
in a practical plant.
The general principles of electrodialysis are as follows. The
process involves the separation of a given flow of water containing
dissolved and ionized solutes into two streams, one more
concentrated and one more dilute than the original, by specially
synthesized semi-permeable membranes. Some ion exchange membranes
are permeable only to cations; thus, only positive ions will migrate
through them under the influence of an electric field. Other ion
exchange membranes, permeable only to anions, will permit migration
of negative ions only.
In electrodialysis, water is fed, usually in parallel, into the
compartments formed by the spaces between alternating cation
permeable and anion permeable membranes held in a stack. At each
end of the stack is an electrode having the same area as the
membranes. A d-c potential applied across the stack causes the
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positive and negative ions to migrate in opposite directions.
Because of the properties of the membranes, a given ion will either
migrate to the adjacent compartment or be confined to its original
compartment, depending on whether or not the first membrane it
encounters is permeable to it. As a result, salts are concentrated
or diluted in alternate compartments.
To achieve high throughput, the electrodialysis cells in practice
are made very thin and assembled in stacks of cells in series. Each
stack consists of more than 100 cells. Feed water is first filtered
to remove suspended particulate matter which could clog the system
or foul the membrane and, if required, is given an ion exchange
treatment to remove oxidizing materials such as ferrous or manganous
ions which would damage the membranes. Very high organic levels may
also lead to membrane fouling. The catholyte stream is commonly
acidified to offset the increase in pH which would normally occur
within the cell, and an antiscaling additive may be required as
well. An operating plant usually contains many recirculation,
feedback and control loops and pumps to optimize the concentrations
and pH's at different points and thus maximize the overall
efficiency.
Relevance to Textile Waste Treatment The mechanism of the
electrodialysis process limits it to the removal of relatively
small, mobile, ionized constituents from the waste stream. Sodium,
potassium, chlorides and sulfates readily pass through the
membranes. Larger ions, and those doubly charged, such as
phosphate, calcium or barium, have limited mobility in the membranes
and tend to remain in the feed stream. There may be some incidental
transport of small dissolved organic species through the membranes
but it is not significant. Electrodialysis has been used
successfully for more than a decade to convert brackish (2000-5000
mg/1 TDS) water to potable water ( 500 mg/1 TDS). While this does
not represent a waste water treatment application per se, it can
provide useful reliability and cost data from the 150 plants which
have been built.
Unfortunately, electrodialysis has not been used to treat textile
plant wastes although some efforts have been made to investigate
its use in dye removal. Because of their large molecular size, dye
materials do not traverse the membranes readily. There may be some
possibility of using electrodialysis to remove dissolved salts from
dye solutions, but this has not yet been demonstrated.
Suspended solids in the feed stream are undesirable. High levels of
organic materials must be avoided as they may attack the membranes.
Thus feed water to the plant should have a low BOD and COD and these
will not be substantially changed by the process.
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Sorption Systems
This group of advanced waste treatment processes is concerned with
methods in which the waste water is contacted with a material which
sorbs components of the water. The material is usually regenerated
and the sorbed material ejected into a gaseous or more concentrated
liquid waste stream. The concentrated liquid waste stream is
normally converted to a solid waste by evaporation. Such processes
include adsorption on activated carbon and ion exchange.
Activated Carbon; Activated carbon is a commercially available and
particularly versatile absorbent primarily because of its relatively
low cost (22 to 1100/kg or 10 to 500/lb) and large surface area
(about 112 hectares per kilogram or 126 acres per pound) which
relates directly to its capacity for adsorbed material (0.7 to 0.9
kilograms of adsorbed material per kilogram of carbon).
The most popular form of activated carbon is the granular, which is
easily handled, deposits the minimum of fines into the water stream,
and may be regenerated by heat with less than 105S loss per cycle.
However, attempts are being made to develop techniques for the use
of powdered carbon, which is considerably less expensive (about
220/kg or 10(Z/lb) than granular carbon (662/kg or 30*/lb) but which
is difficult to separate efficiently from the waste water and
regenerate.
Activated carbon, while acting largely as a general adsorbent, shows
some selectivity:
Strongly Adsorbed Weakly Adsorbed
weak electrolytes strong electrolytes
sparingly soluble very soluble
materials
high molecular wt. low molecular wt.
compounds
The amount of a given material adsorbed is a function of its
chemical nature, the amount in solution, the pH and the temperature.
Typical adsorption capacities of activated carbon at different
residual COD levels are illustrated in Figure 8.
Several types of water carbon contactors have been proposed and
utilized. Usually one or more fixed bed columns are linked in
parallel. Carbon capacity is utilized more efficiently by placing
several fixed bed columns in series, the spent upstream column being
replaced with a regenerated column at the downstream side as approp-
riate. A recent, more efficient development is the use of moving
bed systems.
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The carbon is usually regenerated in multiple hearth furnaces; in
some cases, such as in the adsorption of phenol, partial
regeneration may be achieved by chemical treatment. A schematic of
a treatment process including thermal regeneration is illustrated in
Figure 9.
Relevance to Textile Waste Treatment^ The Environmental Protection
Agency has undertaken detailed studies of the use of activated
carbon for the tertiary treatment of municipal wastes - primarily at
Pomona, California and Lebanon, Ohio. The Pomona plant has been run
for over four years and deserves detailed description.
The plant has a capacity of 1100 cu in/day (0.3 mgd) and is a four-
stage, fixed-bed, granular activated carbon plant.
The carbon is periodically backwashed to remove entrapped suspended
solids and regenerated when necessary after a steady state
adsorption capacity of about 0.4 to 0.5 kilograms of COD per kilo-
gram of carbon has been reached. Carbon losses averaged 8 1/2
percent per cycle. One complete cycle of the 12,200 kilograms
(26,800 pounds) of carbon in the plant is achieved each year of
operation. The effectiveness of the plant in improving water
quality is illustrated in Table 10.
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•Q
If
a
0
en
£!
„*—"*
KlS
1-0
0-1
0.01
.,-""'
.--of
J_
1-0 10-0
(C) Residual COD cone, (ppm)
100-0
Figure 8
COD Isotherms Using Virgin Carbon and
Different Secondary Sewage Effluents
(after Masse, 1967)
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Regenerated
Otiton
influent
Carbon
-^ Effluent
Regenerated
Carbon Storage
Regenerated Carbon
Figure 9
Schematic of an Activated Carbon System
Including Thermal Regeneration
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Table 10
Carbon Adsorption Pilot Plant:
Average Water Quality Characteristics
(June 1965 to July 1969)
Parameter
Suspended solids mg/1
COD mg/1
Dissolved COD mg/1
TOC mg/1
Nitrate as N mg/1
Turbidity (JTU)
Color (Platinum-Cobalt)
Odor
CCE mg/1
BOD mg/1
Influent
9
U3
30
12
8.1
8.2
28
12
—
3
Effluent
0.
10
8
3
6.
1.
3
1
0.
1
6
6
2
026
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About 75% of the influent COD is removed, and the values of most
other parameters such as suspended solids, turbidity, color, odor,
and BOD are reduced to insignificant levels. The effluent water had
an average dissolved COD of 8 mg/1.
Another activated carbon plant studied by the EPA is part of the
advanced waste treatment facility at the District of Columbia's
advanced waste treatment facility. Following lime precipitation,
filtration and water stabilization, the secondary effluent is passed
through five pressurized activated carbon columns in series at a
rate of 190 cu m/day (50,000 gallons per day). When the preceding
clarification was operating efficiently, up to 75 percent of the TOC
was removed by the carbon adsorption system. Because of operating
difficulties the carbon had to be replaced before saturation, at a
loading of only 0.133 kilograms TOC/kilogram carbon.
Activated carbon treatment was also used successfully at Lake Tahoe
to produce drinkable water from secondary effluent. A 28,000 cu
m/day (7.5 million gpd) unit operated at a cost of 60/1000 liters
(230 per 1000 gallons).
Experience with the Use of Activated Carbon on Textile Wastes. The
use of activated carbon to treat textile wastes was pioneered at a
carpet mill in Pennsylvania. Of the raw waste from the dyeing and
rinsing plant, 80 percent was treated and reused. Capacity of the
system was 1900 cu m/day (500,000 gallons per day) and it utilized
22,700 kilograms (50,000 pounds) of granular activated carbon. The
carbon was regenerated by heating it in a furnace.
EPA has supported work in a unique activated carbon system in which
regeneration is accomplished by backwashing the absorbed organic
material into an aerobic biological treatment unit.
After encouraging results in a laboratory unit operating on
synthetic textile waste water, a pilot system was installed at a
carpet yarn fiber dyeing plant. The flow of the pilot system has a
capacity of 190 cu m/day (50,000 gpd).
A range of studies on the treatment of dye waste waters was made by
a textile company in North Carolina. The company encountered only
partial success in the use of carbon for effluent polishing
following biological treatment. In this study anthracite-based
media proved unreliable in removing color contamination; bone char
proved successful but cost about $2.20 per kilogram ($1.00 per
pound) compared to 660 per kilogram (300 per pound) for the former
materials.
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There are several further instances of the use of activated carbon
adsorption for the treatment of textile wastes, particularly in
regard to color removal. A mill in Pennsylvania operates a closed
dye cycle using alum, diatomaceous earth, and carbon to yield a
color of less than 50 units. The consensus appears to be that while
color can be removed by activated carbon, some elements
(particularly the dispersed dyes) are not adsorbed. Chemical
coagulation supplemented by activated carbon adsorption remains the
best method for the dispersed dyes, while carbon adsorption alone
may be adequate for dissolved dyes.
To summarize, activated carbon treatment is a common technique in
industrial processes, has been evaluated in some detail and has been
successful in treating secondary effluent following biological
treatment of municipal waste water. Some successful experience also
has been accumulated in the treatment of textile wastes. The
advanced process is suitable for reducing low-level organic
contamination, but it affects the levels of dissolved ionic solids
very little.
Ion Exchange. Ion exchangers are solid materials, insoluble in
electrolyte solution, which are capable of exchanging soluble anions
or cations with electrolyte solutions. For example, a cation ex-<
changer in the sodium form, when contacted with a solution of
calcium chloride, will scavenge the calcium ions from the solution
and replace them with sodium ions. This provides a convenient
method for removing the "hardness" from waters.
Ion exchange can also be used for total salt removal from waste
streams, by employing a series of beds of anion and cation ex-
changers. The cation exchanger is used in its "acid" form,
exchanging hydrogen ions for the cations in the stream. The anion
exchanger is used in its "base" form, exchanging hydroxyl ions for
the waste stream anions. The hydroxyl and hydrogen ions thus
liberated from the ion exchanger recombine to form water, and thus
replace the salts in the stream by pure water.
The exchange of ions on ion exchangers is stoichiometric and usually
reversible. Thus, after the ion exchanger becomes saturated with
the contaminant ion, it can usually be "regenerated" by flushing
with a concentrated solution of its original ion. The waste
regenerate streams are usually quite concentrated and can be
disposed of economically by simple evaporation.
The most important class of ion exchangers is the organic ion-
exchange resins made from cross-linked polyelectrolytes. The
exchanger exchanges the counter ions to the fixed charges on the
polyelectrolyte. These resins are insoluble but swell to a limited
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degree, allowing ions from solution to penetrate into the gel matrix
formed by the swollen polyelectrolyte.
They are conventionally used in particulate form in packed beds.
The ion exchange behavior of the resins depends on the nature of the
fixed ionic groups, with the exchanger preferring those ions which
strongly associate with the fixed ions.
One of the major advantages of the synthetic resins is the wide
ranges of ion exchange properties which can be built into them,
allowing considerable latitude in the designing of processes. These
exchangers have the additional advantage of being capable of
absorbing non-ionic organic solutes from solution.
In general, ion exchange processes are limited by the selectivity of
the exchanger for the contaminant ion over its own counter ion.
Divalent ions such as calcium and magnesium in general have high
affinities for the ion exchange resins, and can therefore be removed
with extremely high efficiencies. In general, also, ion exchange is
less efficient than electrodialysis or reverse osmosis for high
concentration streams. An upper limit frequently given for effi-
cient removal of ions by ion exchange is 200-500 mg/1, but others
quote efficient cleansing of 2500 mg/1 streams at costs less than
that for electrodialysis or reverse osmosis.
Relevance to Textile Waste Water Treatment. Direct data on the
applicability of ion exchange to textile wastes is scarce.
Extrapolation of data from other waste streams is therefore
necessary. It would appear that the major application of ion
exchange to textile waste treatment would be to reduce the dissolved
solids level of the effluent from the secondary treatment plants or
the effluent from other operations such as electrodialysis or
reverse osmosis. The dissolved solids levels of the secondary
sewage effluents would appear to be in the proper range for
effective use of ion exchange. Costs for a 50 percent reduction of
this salinity, assuming no other complications, would be expected to
be about 120/1000 liters (450/1000 gallons) of product water, not
including the cost of evaporating the concentrated regenerate waste
stream. This latter is estimated to be of the order of 3 to 5
liters of concentrated waste saline per 1000 liters of feed water.
Recently, a new form of organic ion exchange resin has been
developed which may allow economical de-ionization of waste streams
at dissolved salt levels of 1000 to 3000 mg/1. This "Desal" process
is based upon the discovery that certain weakly basic anion exchange
structures can form the bicarbonate salt with solutions of carbon
dioxide, and also have a favorable chloride-bicarbonate selectivity
coefficient. The process relies on a series of three ion exchange
beds.
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This process has been operated successfully at the pilot plant scale
on brackish water; the concentration was reduced to a final effluent
of 20 to 30 mg/1, at an operating cost estimated to be equivalent to
5.30/1000 liters (20ft/ 1000 gallon) (1970) and a total capital
investment for a 3785 cu m/day (1-mgd) plant of about $250,000 (
1970). A commercial plant achieving similar results was operating
in the United States for several years.
More conventional ion exchange resins have been used for the
desalination of brackish water. A pilot plant operation at Pomona,
California has reduced the salinity of tertiary sewage from 1500 to
250 mg/1 with an estimated cost (based on a 37850 cu m/day or 10-mgd
plant) reported to be 2.6 to 6.10/1000 liters (10-230/1000 gallons).
Recently, countercurrent ion exchange has begun to make an impact on
American ion exchange technology. This process allows more
efficient use of regeneration chemicals, and therefore significantly
reduces cost and pollution by regeneration waste streams.
Apparently, European manufacturers of ion exchange equipment have
recognized the savings for some years and have incorporated the new
technology into their systems. It has been predicted that this
technology whose success relies upon novel methods of preventing
fluidization of the ion exchange resin particles during back flow,
will soon become dominant in U.S. markets also, and will lower the
cost of ion exchange use. It is predicted that the cost of reducing
the salinity of waste water containing 1000 mg/1 Nad to 250 mg/1
will be 10 to 120/1000 liters (40-450/1000 gallons), including
amortization of equipment, labor costs, chemicals, etc.
One additional advantage of ion exchange is applicable to highly
alkaline textile waste streams. For example, if the effluent is
sodium hydroxide the cation exchanger alone may be used.
Thus it may be advantageous, where possible, to leave the alkalinity
in the hydroxide form and removing it by ion exchange.
The quality of the waste stream necessary to make ion exchange
feasible is a major factor in its usefulness. The level of
suspended solids in the waste stream can have a considerable
deleterious effect on the long-term operation of the ion exchange
columns. It will therefore be necessary to filter suspended solids
to a low level before allowing the water to enter the ion exchange
columns. Any oxidizing agents in the waste stream will have an
adverse effect on the life of the cation exchangers, while organic
constituents may shorten the life of the anion exchange resins.
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It appears, however, that the projected costs of ion exchange for
textile waste clean-up are sufficiently low to justify a study to
determine long-term applicability.
Polymeric Adsorbtion^_Rgsins. This type of adsorbent is similar in
appearance and structure to ion exchange resins, being solid,
spherical materials insoluble in all aqueous solutions and commonly
used organic solvents. Unlike ion exchange resins, however,
polymeric adsorbents contain no ionic functionality, cationic or
anionic, and function instead as true adsorbents, much like
activated carbon. They are used like activated carbon or ion
exchange resins in fixed-bed columns.
Like carbon, the beads are characterized by high surface area and
specific pore size distributions. Not limited to selection of
naturally-occurring organic materials for its manufacture as is
carbon, the adsorbent resins can be manufactured from a variety of
organic monomers that build in specific attractions for organics
with a wide range of polarity.
The resin beads may be regenerated with two equal volumes of a
common solvent. Methanol is almost universally acceptable. The
adsorbed organics from the waste stream are removed from the resin
bed in this small volume of solvent which is then distilled away
from the concentrated aqueous residue in a distillation column. The
distilled methanol is condensed, recovered, and stored for the next
resin regeneration cycle.
Relevance to Textile Waste Treatment^ Used in conjunction with a
weakly functional ion exchange resins, one class of these polymeric
adsorbents has demonstrated an ability to remove dyestuffs from
aqueous waste streams. The polymeric adsorbent removes the bulk of
the dyestuffs and these dyestuffs eventually appear in the con-
centrated aqueous bottoms of the distillation column, while the
recovered methanol is distilled overhead for the next regeneration
cycle. The ion exchange resin that may be used following the
adsorbent resin bed "polishes" the last traces of dyestuffs from the
effluent before final discharge. Final disposal of the dyestuffs
may be achieved by further concentrating the aqueous bottoms from
the distillation column through evaporation or chemical coagulation
before disposing of the dyestuffs and removed organics by landfill
or by incineration.
One possible advantage over activated carbon involves the treatment
of wastes containing pre-metallized dyes. While both activated
carbon and polymeric adsorbents adsorb these organically-complexed
metal-containing dyes well, thermal regeneration of activated carbon
can burn off the organic portion of the molecule while oxidizing the
metal ion, leaving a metal oxide "enameled" on the surface of the
carbon. This can cause a decrease in adsorbtion capacity of the
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carbon from cycle to cycle unless the "enameled" metal can be
successfully removed with acid washings. Solvent regeneration of
the polymeric adsorbents, on the other hand, has been demonstrated
to be an effective means of desorbing the pre-metallized dyestuffs
without fouling the resin and incurring adsorptive capacity losses.
Studies to date have been carried out on concentrated dye wastes
from manufacturers of textile dyestuffs, dye wastes from
commissioned textile dyers, and on lightly-colored wastes from a
textile mill. Simultaneous with color removal from 1,000 APHA to
100 APHA, COD, and BOD reductions of 60% and HQ% respectively, were
attained.
One commercial installation based on the polymeric adsorbent/ion
exchange resin dye waste treatment system has been operating for
about a year at a U.S. dye producer's plant.
Chemical Clarification
Suspended solids are a significant element of raw textile mill waste
water. The larger components such as lint are readily removed by
screens prior to entering a waste water treatment process.
Residence in a clarifier permits other smaller yet macroscopic
particles to settle as a sludge. Following activated sludge
treatment and clarification, the waste water still contains a varie-
ty of suspended solids. These may be removed by chemical
clarification methods, which, in addition, have been found to be
effective for color removal.
Textile wastes typically contain a complex mixture of suspended
solids, mostly of organic composition. They include color bodies,
proteins, soaps, fibers, mineral fines, oil and grease. Carpet mill
wastes can contain considerable quantities of latex. These
suspended solids have deleterious effects on the other advanced
waste treatment processes used in tertiary treatment of waste
streams; they load secondary treatment plants, blind sorbent beds
and deposit on membrane surfaces. In themselves, they contribute
undesirable properties to the waste water — suspended COD,
turbidity, color, etc.
In addition to the obvious difficulty of removing small particles,
the suspensions are stabilized by two effects: hydration and
electrostatic charge. Most such particles adopt a negative charge
and are prevented from coalescing to the larger, more easily removed
particles by electrostatic repulsion. Neutralization of these
charges destabilizes the system and leads to coagulation and
precipitation or easier filtration. This process is the basis for
chemical clarification.
Coagulation is generally accomplished by adding coagulants that
contain multivalent cations. These include:
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lime, aluminum sulfate, ferric chloride, ammonia alum,
potash alum, ferrous sulfate, ferric sulfate and sodium
aluminate.
The multivalent cations A1+++, Fe+++ and Fe++ are strongly hydrated
and hydrolyzed, forming acidic solutions. Sodium aluminate, on the
other hand, forms a strongly alkaline solution and is sometimes used
in combination with aluminum sulfate to improve the resulting floe.
Addition of coagulants to the suspended solids and colloidal
substances produces a floe which is allowed to settle in a clarifier
using gentle agitation. It is important to dissipate the coagulant
throughout the waste water as fast as possible; flash mixing at
point of entry to the clarifier is normally used.
The correct coagulant dose for a specific waste water and
particularly the precise pH for maximum effectiveness must be
determined experimentally. Unfortunately, the optimum values of
these parameters may not be the same for different components of the
waste water; thus turbidity removal may demand an operating pH
different from that needed for color removal.
Coagulant aids may also be used to create larger, tougher floes that
are more amenable to sedimentation or filtration. Activated silica
has been used for many years; more recently, water soluble polymers,
usually polyelectrolytes, have been used successfully for this
purpose. They are available in anionic, cationic, or neutral form
to treat floes of differing electrostatic characteristics.
Relevance to Textile Waste Water Treatment^ Coagulation and
flocculation is a widely used technique in waste water treatment and
in the preparation of potable water. Costs typically range from 1-
5
-------
In Israel, experimental results showed that flocculation with alum
and filtration would reduce color by 95% and turbidity by 97% in a
highly colored simulated waste water. Performance was shown to be a
strong function of pH and alum dosage; maximum reduction of color
levels and turbidity did not necessarily occur at the same pH value.
The cationic polyelectrolytes were found to be effective coagulant
aids, but only at very high doses (about 30 mg/1).
The treatment of wool processing effluent using coagulants has been
discussed by Stewart. Calcium chloride coagulation was used in a
plant England. Addition of 2,000 mg/1 of calcium chloride followed
by filtration reduced a BOD of 15,000 to 30,000 mg/1 to 2,700 to
3,800 mg/1, suspended solids of 20,000 to 32,000 mg/1 to 1,000 mg/1
and grease levels of 17,000 to 20,000 mg/1 to 50 mg/1. But the cost
was over $1.30 per 1000 liters ($5 per 1,000 gallons) in 1964.
In a review of treatment methods for dye waste waters, it was
reported that the most successful coagulation technique for color
removal consisted of the use of alum or a combination of alum and a
cationic polyelectrolyte. Treatment of wastes before and after
activated sludge treatment was studied; in general, less chemical
requirement was found prior to biological treatment. Mixed liquor
treated with 150 to 250 mg/1 alum, 10 mg/1 lime and 20 mg/1 cationic
polymer produced an effluent color with zero suspended solids, but
the chemical cost alone was 2.1 to 2.60/1000 liters (8 to 100/1000
gallons). If chemical clarification must follow biological
treatment, 200 to 400 mg/1 alum and no coagulant aid may be used.
Color removals of about 95 percent can be expected.
The use of a polyelectrolyte has been found to be a useful aid to
alum dewatering in other work.
A company in Pennsylvania reports successful color removal of a
closed dye cycle water using a combination of alum treatment,
diatomaceous earth filtration and carbon adsorption.
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SECTION VIII
COST, ENERGY, AND NON-WATER QUALITY ASPECTS
and Reduction Benefits of Alternative Treatment and Control
Technologies
A detailed economic analysis showing the cost effectiveness of
various treatment and control technologies upon the seven
sutcategories within the textile industry is given in this document.
Five alternative treatment methods have been considered for
Subcategories 1 to 7, For the eight subcategories, the alternatives
include:
Alternative A - No waste treatment or control.
Alternative B - Preliminary and biological treatment.
Alternative C - Multi-media Filtration,
Alternative D - Muli-media Filtration and Chemical Coagulation.
Alternative E - Activated Carbon Adsorption.
Alternative F - Multiple Effect Evaporation and Incineration.
Basis of Economic Analysis - Following is a summary of the basis for
cost estimates:
1• Investment - Investment costs have been derived
principally from published data on waste water treatment
plant construction costs, consultants* cost data, and
information from equipment manufacturers and suppliers.
Published cost data for treatment facilities is derived
primarily from experience with waste water treatment
installations. Cost information has been reported by
some textile manufacturers, but the data are not
extensive enough to serve as a basis for the estimates
presented herein. Basic data were developed by
preparation of graphical relationships between cost and
size for each unit operation. Based on treatment plant
configuration, design criteria, and size, costs for
individual unit operations were added together to
determine major facility costs.
An allowance of 15 percent of the total investment has
been included as yardwork which includes general site
clearing and grading inter-component piping, lighting,
control structures, road paving, and other items outside
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the structural confines on an individual plant
component. An additional allowance of up to 25 percent
of the total investment has been included to cover land,
contingencies, engineering and overhead.
2. Depreciation and Cost of Capital (Interest) - It was
assumed that the annual interest costs (cost of capital)
and depreciation would be constant over the life of the
treatment facilities. A principal repayment period of
10 years was used. Costs were depreciated on a straight
line basis and the depreciation period of 10 years was
assumed equal to the principal repayment period and the
economic life of the facilities.
Cost of money was assumed to be an average of the cost
of debt capital and the cost of equity capital. Cost of
debt capital was assumed to be 8 percent and the cost of
equity capital 22 percent. Data for the last 10 to 12
years indicated that the average net return on equity
capital for the chemical industry and other
manufacturing has been 10 to 12 percent. Assuming
corporate income tax is equal to net return (50* of
gross return), gross return is estimated to be debt
capital and 40 percent equity capital. From this
analysis, an average rate for the cost of money equal to
13.6 percent was determined. An average annual value
for cost of money was derived by subtracting the
straight line depreciation cost from the investment
cost, times the capital recovery factor. The costs were
about 8 percent of the capital investment.
3. Insurance_and^Taxes - An annual cost of 1 1/2 percent of
the initial investment was used for insurance and taxes
on the waste treatment plant.
4. Operation and Maintenance Labor - Operation and
maintenance labor manhour requirements were based on
published data and independent estimates. The
operational requirements include general management and
supervisory personnel, equipment operators and laborers,
and clerical and custodial personnel. Maintenance labor
includes mechanical, electrical, laborers, and other
appropriate repair personnel.
Based on labor rates in the Textile industry and
municipal waste water treatment plants on August, 1971
average labor rate of $5.00 per hour (including fringe
maintenance labor costs).
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5. Chemicals - Chemical costs used in the economic
analysis are based on published literature typical in
the U.S. The costs used are:
Lime - $22.00 per metric ton ($20.00 per ton)
Soda Ash - $3.96 per 100 kilograms ($1.80 per 10C pounds)
Ferric Chloride - $8.80 per 100 kilograms ($4.00 per 100
pounds)
Polymer - $0.44 per kilogram ($0.20 per pound)
Chlorine - $13.20 per 100 kilograms ($6.00 per 100 pounds)
Sulfuric Acid - $36.40 per metric ton ($33.00 per ton)
Ammonia - $35.90 per metric ton ($32.50 per ton)
6« Energy - In broad context, energy includes electric
power and fuel. Electric power consumption for major
units such as aeration, pumping, and mixing was
estimated from available data. An allowance of ten
percent was made for small power users such as
clarifiers, chemical feed equipment, ventilation
equipment, and so forth. The cost of electric power was
assumed to be $0.015/kwhr. Motor efficiency was assumed
to be 70 percent.
For alternative E, steam is required for evaporation.
The cost of steam ranged from $1.76 to $2.42/1,000 kg of
steam ($0.80 to $1.10/1,000 Ib of steam).
Information on actual treatment cost experience in the textile
industry was available in varying degrees of completeness from the
exemplary plants visted. To verify the quality of the data received
and to provide a broader basis for estimation, a costing model was
developed based on standard waste water treatment practice. This
model covers both capital and operating costs for the equivalent of
what appears to be the best technology currently practiced by the
industry: essentially primary and secondary treatment as extended
aeration with stabilization ponds. Over a plant size range of 400-^
12,000 cubic meters per day (0.1 to 3.0 MGD), the cost experience
data from the plants visited came within 30 percent of that
predicted by the cost model, as shown by the examples in Table 11.
The costs calculated from the model, therefore, are believed to be
realistic bases for estimating the (replacement) value of existing
facilities and the economic impact of further secondary-type
treatment requirements.
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Cost curves developed from the cost model are presented in Figures
10 to 18. (For very small plants (about 110 cu m/day or 30,000
gpd), an overall cost figure of $264 for 1 cu m/day or $1.00 for 1
gpd was assumed.) Figures 14 to 18 present the operating and
maintenance costs over the ranges of production found. The initial
capital cost of biological treatment systems depends mainly upon
(and here is related to) the hydraulic load, the other factors
making only minor variations in the total cost. Operating costs, on
the other hand, have been viewed as dependent on pollutant as well
as hydraulic loads.
Costs for representative large plants in industry categories were
developed using these curves and assuming an aerated stabilization
basin, which is widely used by the industry when land is readily
available. The following items were determined for the individual
treatment steps:
(1) Construction costs as function of hydraulic load at a
given pollutant level;
(2) Operating and maintenance labor as a function of hydrau-
lic load;
(3) Chemical requirements as a function of hydraulic and
pollutant load;
(4) Power requirements as a function of hydraulic and pollu-
tant load;
(5) Additional material and supply cost as a function of
hydraulic load.
Costs have been adjusted to a national average cost level of January
1973 using the ENR construction Cost Index. The estimated cost
curves have been adjusted to exclude unusual construction or site-
specific requirements. The curves include all elements of
construction cost which a contract bidder would normally encounter
in completing the waste water treatment. Included are building
materials, labor, equipment, electrical, heating and ventilation,
normal excavation and other similar items. Also included are the
engineering costs. The annual operating costs include operation and
maintenance labor, chemicals, power, material and supplies, and
depreciation.
126
-------
TABLE H
Accuracy Of Standardized Costing Methodology
Example Plant
EPA
cost estimate
company reported
cost for actual plant
Ratio
EPA
reported
Plant A (0.394 MGD)
Subcategory 1
Aeration basin
Aeration equipment
Clarifier
3 day lagoon
yard work (15% const)
engineering
Plant Q (2.5 MGD)
Subcategory 4
Aeration
Aeration equipment
Clarifier
3 day lagoon
yard work (15% const)
engineering
Plant X (1.7 MGD)
Subcategory 5
Aeration basin
Aeration equipment
Clarifier
3 day lagoon
yard work (15% const)
engineering
$ 27,000
136,900
35,600
12.500
$212,000
31,800
42,400
$286,200
$ 59,000
123,400
116,400
3.200
$330,800b
49,600
60,000
$440,400
$ 57,000
23,600
98,800
27,000
$206,400
31,000
47,000
$284,400
$210,000
1.36
$554,000
0.79
$335,400
.85
(Land cost left off these estimates in order to compare with plant reported
cost—maximum land cost, plant Q, is $6,000)
127
-------
1,000,000
o
Q
100,000
10,000
10.0
Figure 10
Aerated Stabilization Basin Construction Cost
128
-------
10,000
§
O)
c
100
10
100
1,000 10,000
Total Construction Cost, ($000)
100,000
Figure 11
Engineering Costs
129
-------
o
Q
tt
8
10x105
1 x 105
I i I i i i 11
1. L I I I I I
ENR Index =1811.93,
Jan. 1973
1.0
10.0
100.0
Flow, mgd
Figure 12
Clarifier Capital Cost
130
-------
10x105
. i.0xio5
tt
o
O
li III
1,000
ENR Index = 1811.93, Jan. 1973
10,000
BOD removal, Ib/day
i i i i
100,000
Figure 13
Aerated Stabilization Basin
(Aeration Equipment Only)
131
-------
10,000
o
c
to
§ 1,000
Operation
Maintenance
100
i i i
I I I L
1.0
10.0
Flow, mgd
100.0
Figure 14
Aerated Stabilization Basin
Annual Operation and Maintenance Labor
132
-------
10,000
o
O
CO
c
1,000
Chemicals for "Typical" Plants
ENR = 1811.93, Jan. 1973
Aerated Stabilization Basin
(Material and Supply Costs, Annual)
(Chemical Costs)
100.0
133
-------
100,000
o
a
o 10,000
c
c
1,000
1,000
10,000
BOD removal, Ib/day
Figure 16
Aeration Equipment
Annual Power Costs
(Aerated Stabilization Basin)
100,000
134
-------
10,000
o
c
(0
- 1,000
D
C
C
100
1.0
Operation
Maintenance
i i i i
i i i I i i
10.0
Flow, mgd
100.0
Figure 17
Clarifier, Annual Operation
and Maintenance Labor
135
-------
100.000
o
Q
Q 10,000
c
1,000
Material and Supply Costs
10.0
Flow, mgd
Figure 18
Clarifier
(Material and Supply Costs, Annual)
(Major Chemical Costs)
100.0
136
-------
Cost Effectiveness of Treatment Alternatives
Alternative A - No Waste Treatment or Control
Costs - None
Reduction Benefits - None
t;
Alternative B - Preliminary and Biological Treatment
This alternative includes preliminary screening, primary
clarification (wool scouring only) and biological treatment.
Costs - The total capital investment cost is estimated to range from
$10,200 to $478,000 for the model plants. The annual treatment cost
is estimated to range from $3,900 to $123,000.
Reduction Benefits - Alternative B represents about a 95 percent
reduction in BODJ5 compared with Alternative A. There are also
significant reductions in TSS and some reduction of COD. Other
reductions include total chromium, phenol and sulfide. Oils and
grease are reduced from wool scouring operations.
Alternative C - Multi-media Filtration
This alternative consists of a filtration process that is compatible
with biological treatment (Alternative B).
Costs - Alternative C represents a total capital investment of from
$10,000 to $140,000 over Alternative B costs and an increased annual
cost estimated to range from $3,000 to $41,300.
w
Reduction Benefits - Alternative C represents a further reduction in
BOD5 and a substantial TSS reduction due to solids removal and
optimum control over the biological treatment system.
Alternative D - Chemical coagulation/clarification and multi-media
filtration.
Alternative D consists of chemical addition for
coagulation/clarification followed by multi-media filtration.
Within the textile industry this alternative is a compatible
supplement to biological treatment (Alternative B).
Costs - Chemical coagulation/clarification followed fay multi-media
filtration would represent a cost of $107,000 to $816,000 in
addition to the cost of Alternative B, with annual costs ranging
from $28,000 to $228,000.
137
-------
Reduction Benefits - The effluent treatment through the addition of
Alternative D to Alternative B will result in the further reduction
of BOD and removal of a major portion of TSS, COD, and color.
Alternative E - Activated Carbon Adsorption
Alternative E includes an activated carbon adsorption systam
including carbon regeneration facilities. This system is compatible
with biological treatment (Alternative B) and may require filtration
(Alternative C). It may also be used for total effluent treatment.
Costs - Alternative E represents a total capital investment which
ranges from $151,000 to $1,050,000 over Alternatives B or C and an
increased annual cost from $41,000 to $404,800.
Reduction Benefits - Through Alternative E, there are some
reductions in BODJ5 and TSS. There are significant reductions in
COD, TOG, and color.
Alternative F - Multiple Effect Evaporation and Incineration
Alternative F includes a multiple effect (three stage) evaporator
and a fluidized bed incinerator. Residual solids are disposed of by
landfill.
Costs - The capital investment is estimated to range from $196,000
to $3,148,00 and annual costs are estimated to range from $95,000 to
$2,210,000.
Reduction Benefits - There would be complete removal of all waste
water constituents. There would be no waste water discharge.
Impact of Waste Treatment Alternatives on Finished Product
Tables 12-18 illustrate the probable increases in finished product
prices for small, medium and some large size plants in the seven
textile subcategories required to pay for waste water treatment.
The costs to those plants identified as Commission Finishers
(Subcategory 8) within each subcategory will be comparable to the
costs presented in the tables as representative for that
subcategory. Each table lists the increased cost attributable to
biological treatment (Alternative B) and the additional cost
increases in finished product prices for multi-media filtration
(Alternative C), chemical coagulation/chlorification followed by
multi-media filtration (Alternative D), activated carbon adsorption
(Alternative E) and multiple effect evaporation and incineration
(Alternative F). Several conclusions are apparent from this
economic analysis.
138
-------
(1) The best practicable control technology currently
available (as represented by Alternative B) is
economically feasible for all sizes of plants in all
subcategories. As shown in the tables the estimated
final product cost increases for the various
subcategories will range from 0.6 cents per kilogram of
product (0.3 cents per pound of product) to 2.8 cents
per kilogram of product (1.3 cents per pound of product)
with the average price increase about 2.0 cents per
kilogram product (0.9 cents per pound product).
(2) Multi-media filtration (Alternative C), which is
recommended as a part of pollutant control technology
for new sources, will necessitate only a minor price
increase over Alternative B. The costs and price
increases are minimal and should have an insignificant
impact on new plants. The impact on small plants has
been evaluated and determined not to be significant.
The maximum cost for any size plant is less than 1.8
cents per kilogram product (0.8 cents per pound of
product) with the average cost less than 0.85 cents per
kilogram of product (0.4 cents per pound of product.
(3) The possible price increases for the addition of
chemical coagulation and multi-media filtration
(Alternative D) to biological treatment (Alternative B)
average 3.8 cents per kilogram of product (1.7 cents per
pound of product) with the range being from 0.7 cents
per kilogram of product (0.3 cents per pound of product)
to 5.3 cents per kilogram (2.4 cents per pound of
product.) This cost increase calculated for best
available technology is economically achievable, even
for plants of all sizes. The impact on small plants has
been evaluated and determined not to be significant.
(4) Activated carbon adsorption (Alternative E) has been
included as a treatment alternative either in
combination with or in place of biological treatment.
The costs of carbon adsorption as an addition to a
biological system, range from 1.8 cents per kilogram of
product (0.8 cents per pound of product) to 23.3 cents
per kilogram of product (10.4 cents per pound of
product). The average of the potential pass-through
price increase is 7.6 cents per kilogram of product (3.3
cents per pound of product) with smaller plants having
their costs tending to be comparable to or greater than
the average and the costs to the plants identified as
medium-sized tends to be lower than the average. The
economies of scale are pronounced with this system and
favor the larger plants for economically using this
139
-------
Alternative. Therefore it is included as an alternative
for those plants working to achieve BATEA and able to
obtain the economies of scale of this system.
(5) The estimated costs and price increases associated with
the use of evaporation and incineration to achieve an
equivalent of zero discharge, appear to be excessive for
all industry subcategories except for the wool scouring
subcategory. The price increases that could result from
the installation of Alternative F range from less than
5.3 cents per kilogram (2.4 cents per pound) of product
(for larger wool scouring plants) to 63.7 cents per
kilogram of product (28.4 cents per pound of product).
The average price increase would be 30.9 cents per
kilogram (13.8 cents per pound) of product in excess of
other "best available" technologies as opposed to 7.8
cents per kilogram (3.5 cents per pound of product) over
comparable treatment systems for wool scouring plants.
Thus, no discharge of pollutants via evaporation and
incineration is a feasable alternative treatment for
wool scouring plants.
Tables 12-18 indicate the possible costs and price increases for
various alternatives associated with the application of BPCTCA,
BATEA and NSPS within all subcategories throughout the various
size-classes of plants. The average price increase for BPCTCA of
2.0 cents per kilogram (0.9 cents per pound) of product will have a
minimal effect on the industry. The incremental addition of BATEA
with an average price increase of 3.2 cents per kilogram (1.4 cents
per pound) of product in excess of BPCTCA, when viewed as an
increase spread over five years presents no threat to the present
industry prospectus. The economics of scale associated with larger
plants is ameliorated by the time frame within the application of
the guidelines and the minor repercussions of this scale factor will
not affect the competitive position of smaller plants within the
market place. The ability to pre-design treatment systems within
new sources effectively eliminates the impact of the guidelines on
the prices that products produced by new sources must bring. The
costs presented in the Tables are representative though possibly
excessive allowances in the cases of new sources. Therefore the
effluent limitation guidelines for the textile industry for BPCTCA,
BATEA, and NSPS will have an overall minor effect on the industry.
140
-------
TABLE 12
WASTE WATER TREATMENT COSTS FOR WOOL SCOURING (SUBCATEGORY 1)
ALTERNATIVE
PRODUCTION
1000 kg/day
(1000 Ib/day)
WATER CONSUMPTION
1000 I/day
(1000 gal/day)
CAPITAL
INVESTMENT
($1,000)
ANNUAL COST
($1,000)
ESTIMATED COST
C/kg product
(C/lb product)
20.4
45.0
257.4
68.0
151.0
41.0
0.8
0.4
B
48.0
105.6
719.1
190.0
265.0
71.0
0.6
0.3
ALTERNATIVE
6.0
13.3
75.7
20.0
15.0
4.4
0.3
0.1
C
30.3
66.7
378.9
100.1
38.0
11.2
0.3
0.1
ALTERNATIVE
20.4
45.0
257.4
68.0
107.0
28.0
0.5
0.2
D
48.0
105.6
719.1
190.0
156.0
43.0
0.4
0.2
ALTERNATIVE
6.0
13.3
75.7
20.0
151.0
41.0
2.7
1.2
E
30.3
66.7
378.9
100.1
480.0
135.6
1.8
0.8
ALTERNATIVE
6.0
13.3
257.4
20.0
392.0
190.0
12.7
5.7
F
30.3
66.7
719.1
100.1
768.0
398.0
5.3
2.4
ALTERNATIVE B = Preliminary and Biological Treatment
ALTERNATIVE C = Multi-Media Filtration
ALTERNATIVE D = Chemical Coagulation/Clarification and Multi-Media Filtration
ALTERNATIVE E = Activated Carbon Adsorption
ALTERNATIVE F = Multiple Effect Evaporation and Incineration
-------
TABLE 13
WASTE WATER TREATMENT COSTS FOR WOOL FINISHING (SUBCATEGORY 2)
ALTERNATIVE
B
PRODOCTION
1000 kg/day
(1000 Ib/day)
WATER CONSUMPTION
1000 I/day
(1000 gal/day)
CAPITAL
INVESTMENT
($1,000)
ANNUAL COST
($1,000)
ESTIMATED COST
C/kg product
(C/lb product)
4.3
9.5
495.8
131.0
98.0
30.0
2.8
1.2
15.2
33.5
1,748.7
462.0
205.0
59.0
1.6
0.7
25.0
55.0
2,872.8
759.0
278.0
79.0
1.3
0.6
ALTERNATIVE
C
8.2
18.1
946.0
250.0
60.0
17.7
0.9
0.4
24.7
54.3
2,840.0
750.0
135.0
39.8
0.6
0.3
ALTERNATIVE
D
4.3
9.5
495.8
131.0
197.0
49.0
4.6
2.0
15.2
33.5
1,748.7
462.0
349.0
89.0
2.3
1.1
25.0
55.0
2,872.8
759.0
441.0
114.0
1.8
0.8
ALTERNATIVE
E
8.2
18.1
943.0
250.0
450.0
132.8
6.5
2.9
24.7
54.3
2,840.0
750.0
910.0
292.5
4.7
2.1
ALTERNATIVE
F
8.2
18.1
943.0
250.0
1,316.0
759.0
37.0
16.7
24.7
54.3
2,840.0
750.0
2,991.0
2,087.0
33.8
15.3
ALTERNATIVE B = Preliminary and Biological Treatment
ALTERNATIVE C = Multi-Media Filtration
ALTERNATIVE D = Chemical Coagulation/Clarification and Multi-Media Filtration
ALTERNATIVE E = Activated Carbon Adsorption
ALTERNATIVE F = Multiple Effect Evaporation and Incineration
-------
TABLE 14
WASTE WATER TREATMENT COSTS FOR DRY PROCESSING (SUBCATEGORY 3)
ALTERNATIVE ALTERNATIVE ALTERNATIVE
B C F
PRODUCTION
1000 kg/day 1.5 1.5 1.5
(1000 Ib/day) 3.3 3.3 3.3
WATER CONSUMPTION
1000 I/day 18.9 18.9 18.9
(1000 gal/day) 5.0 5.0 5.0
CAPITAL
INVESTMENT 10.2 10.0 196.0
($1,000)
ANNUAL COST 3.9 3.0 95.0
($1,000)
ESTIMATED COST
CAg product 1.0 0.8 25.3
(t/lb product) 0.4 0.3 9.6
ALTERNATIVE B = Preliminary and Biological Treatment
ALTERNATIVE C = Multi-Media Filtration
ALTERNATIVE F = Multiple Effect Evaporation and Incineration
-------
TABLE 15
WASTE WATER TREATMENT COSTS FOR WOVEN FABRICS (SUBCATEGORY 4)
ALTERNATIVE
PRODUCTION
1000 kg/day
(1000 Ib/day)
WATER CONSUMPTION
1000 I/day
(1000 gal/day)
CAPITAL
INVESTMENT
($1,000)
ANNUAL COST
($1,000)
ESTIMATED COST
£/kg product
(£/lb product)
4.1
9.0
605.6
160.0
86.0
27.0
2.6
1.2
B
32.9
72.5
4,920.0
1,300.0
278.0
79.0
1.0
0.4
6S.1
150.0
10,220.0
2,700.0
442.0
123.0
0.7
0.3
ALTERNATIVE
2.5
5.6
382.0
101.0
38.0
11.2
1.8
0.8
C
12.6
27.8
1,893.0
500.0
102.0
30.1
1.0
0.4
ALTERNATIVE
4.1
9.0
605.6
160.0
217.0
54.0
5.3
2.4
D
32.9
72.5
4,920.0
1,300.0
570.0
152.0
1.8
0.8
68.1
150.0
10,220.0
2,700.0
816.0
228.0
1.3
0.6
ALTERNATIVE
2.5
5.6
382.0
101.0
450.0
145.8
23.3
10.4
E
12.6
27.8
1,893.0
500.0
860.0
372.7
11.8
5.4
ALTERNATIVE
2.5
5.6
382.0
101.0
768.0
398.0
63.7
28.4
F
12.6
27.8
1,893.0
500.0
2,197.0
1,472.0
48.7
21.2
ALTERNATIVE B = Preliminary and Biological Treatment
ALTERNATIVE C = Multi-Media Filtration
ALTERNATIVE D = Chemical Coagulation/Clarification and Multi-Media Filtration
ALTERNATIVE E = Activated Carbon Adsorption
ALTERNATIVE F = Multiple Effect Evaporation and Incineration
-------
TABLE 1b
WASTE WATER TREATMENT COSTS FOR KNIT FABRICS (SUBCATEGORY 5)
ALTERNATIVE
B
PRODUCTION
1000 kg/day
(1000 Ib/day)
WATER CONSUMPTION
1000 I/day 1,
(1000 gal/day)
CAPITAL
INVESTMENT
($1,000)
ANNUAL COST
($1,000)
ESTIMATED COST
-------
TABLE 17
WASTE WATER TREATMENT COSTS FOR CARPET MILLS (SUBCATEGORY 6)
ALTERNATIVE
B
pfiODuenoN
1000 kg/day
(1000 Ib/day)
WftTER CONSUMPTION
1000 I/day
(1000 gal/day)
CAPITAL
INVESTMENT
(SI, 000)
ANNUAL COST
($1,000)
ESTIMATED COST
CAg product
, (C/lb product)
7.0
15.5
492.0
130.0
98.0
30.0
1.4
0.7
43.2
95.2
3,028.0
800.0
200.0
57.0
0.4
0.2
ALTERNATIVE
C
5.4
11.9
378.5
100.0
38.0
11.2
0.7
0.3
43.2
95.2
3,028.0
800.0
140.0
41.3
0.3
0.1
ALTERNATIVE
D
7.0
15.5
495.0
130.0
197.0
49.0
2.3
1.1
43.2
95.2
3,028.0
800.0
452.0
118.0
0..9
0.4
ALTERNATIVE
. E
5.4
11.9
378.5
100 :o
400.0
116.0
7.2
3.2
43.2
95.2
3,028.0
800.0
1,050.0
404.8
3.1
1.4
ALTERNATIVE
F
5.4
11.9
378.5
100.0
768.0
398.0
24.6
11.1
43.2
95.2
3,028.0
800.0
3,148.0
2,210.0
17.1
7.7
ALTERNATIVE B = Preliminary and Biological Treatment
ALTERNATIVE C = Multi-Media Filtration
ALTERNATIVE D = Chemical Coagulation/Clarification and Multi-Media Filtration
ALTERNATIVE E = Activated Carbon Adsorption
ALTERNATIVE F = Multiple Effect Evaporation and Incineration
-------
TABLE 18
WASTE WATER TREATMENT COSTS FOR STOCK & ¥ARN (SUBCATEGORY 7)
ALTERNATIVE
B
PRODUCTION
1000 kg/day
(1000 Ib/day)
WATER CONSUMPTION
1000 I/day
(1000 gal/day)
CAPITAL
INVESTMENT
($1,000)
ANNUAL COST
($1,000)
ESTIMATED COST
C/kg product
(C/lb product)
5.0
11.0
916.0
242.0
110.0
33.0
2.2
1.0
10.9
24. '0
1,999.0
528.0
170.0
49.0
1.5
0.7
27.2
60.0
4,996.0
1,320.0
293.0
83.0
1.0
0.5
ALTERNATIVE
C
4.1
9.1
752.0
200.2
59.0
17.4
1.4
0.6
12.4
27.3
2,275.0
600.6
120.0
35.4
1.0
0.4
ALTERNATIVE
D
5.0
11.0
916.0
242.0
256.0
64.0
4.3
1.9
10.9
24.0
1,999.0
528.0
372.0
95.0
2.9
1.3
27.2
60.0
4,996.0
1,320.0
574.0
153.0
1.9
0.9
ALTERNATIVE
E
4.1
9.1
752.0
200.2
400.0
116.0
9.4
4.2
12.4
27.3
2,275.0
600.6
730.0
221.4
6.0
2.7
ALTERNATIVE
F
4.1
9.1
752.0
200.2
1,132.0
638.0
51.9
23.3
12.4
27.3
2,275.0
600.6
2,521.0
1,1721.0
46.3
21.0
ALTERNATIVE B = Preliminary and Biological Treatment
ALTERNATIVE C = Multi-Media Filtration
ALTERNATIVE D = Chemical Coagulation/Clarification and Multi-Media Filtration
ALTERNATIVE E = Activated Carbon Adsorption
ALTERNATIVE F = Multiple Effect Evaporation and Incineration
-------
Alternative Treatment Systems
It has been assumed in the economic analysis that an extended
biological stabilization process will be utilized for the biological
treatment. However, aerobic-anaerobic lagoons or trickling filters
or activated sludge can be designed to provide the same degree of
biological treatment. These systems require less area and can be
utilized where land is not readily available near the textile
facility. Activated sludge may result in additional annual costs of *
as much as $200,000 over those costs presented for Alternative B.
Wool scouring plants (Subcategory 1) with capacities greater than
6,500 kg/day (14,300 Ib/day) may be able to economically utilize
activated carbon adsorption. Table 12 indicates that
evaporation/incineration could be a feasible alternative for large
wool scouring plants. Costs could be only 3.5 cents per kilogram of
product (1.6 cents per pound product) higher.
Electrica1 Energy Requirementg
The energy requirements (electric power and fuel) for textile
facilities vary considerably based upon reported data. This
variation is due to the following factors:
1. Type of fiber processed.
2. Type of extent of cleaning and finishing operations.
3. Degree of mechanization within the textile facility.
4. Climate of the textile location.
It is estimated that the contribution of waste treatment is
considerably less than 10 percent of the total industry energy
consumption at present and is not likely to exceed 10 percent in the
future.
Thermal Energy Requirements
Thermal energy costs are considerably less than electrical energy
costs for operations within the industry. Waste treatment systems
impose no significant addition to the thermal energy requirements of
plants. Wastewater can be reused in cooling and condensing service
if it is separated from the process waters in non-barometric type
condensers. These heated waste waters improve the effectiveness of
ponds which are best maintained at 90°F or more. Improved thermal
efficiencies are coincidentally achieved within a plant with this
technique.
1U8
-------
Wastewater treatment costs and effectiveness can be improved by the
use of energy and power conservation practices and techniques in
each plant. The waste load increases with increased water use.
Reduced water use, therefore, will reduce the waste load, pumping
costs, and heating costs; the last of which can be further reduced
by water reuse as suggested previously.
Solid Hastes
The solid wastes from the textile industry are generally disposed of
by landfill. The solid materials, separated during waste water
treatment, containing organic and inorganic materials, including
those added to promote solids separation, is called sludge.
Typically, it contains 95 to 98 percent water prior to dewatering or
drying. Some quantities of sludge are generated by both primary and
secondary treatment systems with the type of system influencing the
quantity. The following table illustrates this:
Treatment System
Dissolved air flotation
Anaerobic lagoon
Extended aeration
Aerobic 6 aerated lagoons
Activated sludge
Extended aeration
Anaerobic contact process
Sludge Volume as Percent of
Raw Wastewater Volume
Up to 10%
(Sludge accumulation
in these (lagoons is
usually sufficient to
require removal at any
time)
10
5
- 15%
- 10%
approximately 2%
The raw sludge can be concentrated, digested, dewatered, dried,
incinerated, land-filled, or spread in sludge holding ponds. Sludge
from secondary treatment systems is normally dewatered or digested
sufficiently for hauling to a land fill. The final dried sludge
materials can be safely used as an effective soil builder.
Prevention of runoff is a critical factor in plant-site sludge
holding ponds. Costs of typical sludge handling techniques for each
secondary treatment system generating enough sludge to require
handling equipment are already incorporated in the costs for these
systems. All other non-water quality environmental impacts of the
alternative treatment and control technologies described appear to
be minor.
-------
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SECTION IX
EFFLUENT REDUCTION ATTAINABLE THROUGH THE
APPLICATION OF THE BEST PRACTICABLE CONTROL
TECHNOLOGY CURRENTLY AVAILABLE
EFFLUENT LIMITATIONS GUIDELINES
INTRODUCTION
The effluent limitations which must be achieved July 1, 1977, are to
specify the degree of effluent reduction attainable through the
application of the Best Practicable Control Technology Currently
Available. Best Practicable Control Technology Currently Available
is generally based upon the average of the best existing performance
by plants of various sizes, ages, and unit processes within the
industrial category and/or subcategory. This average is not based
upon a broad range of plants within the textile industry, but based
upon performance levels achieved by exemplary plants.
Consideration must also be given to:
The total cost of application of technology in relation to
the effluent reduction benefits to be achieved from such
application;
The size and age of equipment and facilities involved;
The processes employed;
The engineering aspects of the application of various types
of control techniques;
Process changes;
Non-water quality environmental impact (including energy
requirements).
Also, Best Practicable Control Technology Currently Available
emphasizes treatment facilities at the end of a manufacturing
process, but includes the control technologies within the process
itself when the latter are considered to be normal practice within
an industry.
A further consideration is the degree of economic and engineering
reliability which must be established for the technology to be
"currently available". As a result of demonstration projects, pilot
plants and general use, there must exist a high degree of confidence
in the engineering and economic practicability of the technology at
151
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the time of start of construction of installation of the control
facilities.
EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION OF
BEST PRACTICABLE CONTROL TECHNOLOGY CURRENTLY AVAILABLE
Based on the information contained in Section III through VIII of
this report, a determination has been made that the quality of
effluent attainable through the application of the Best Practicable
Control Technology Currently Available is as listed in Table 19. A
number of plants in the industry which have biological treatment
systems for which effluent quality data were available are meeting
these standards.
A biological treatment system which is permitted to operate at a
constant food to microorganism ratio throughout the year and with
minimum operational changes would have a natural variation of 50
percent as explained in Section VII and as shown by the solid line
in Figure 19. A similar system with careful operational control and
proper design can be operated within 25 percent of the average on a
monthly operating basis. A biological treatment system without
optimum operational control has been used to account for normal
treatments variation. Thus, a factor of 50 percent has been used to
calculate the maximum 30 day effluent limitations. A further
allowance of 100 percent has been applied to maximum 30 day effluent
limitations in order to develop the maximum daily effluent
limitations. This factor results from the inherent variability
associated with a textile manufacturing operation.
152
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Table 19
Maximum Thirty Day Average
Effluent Limitations Guidelines (1)
for July 1, 1977
BOD5
5.3
11.2
0.7
3.3
2.5
3.9
3.4
kg(lb) poll
kkg(1000 Ib)
TSS
16.1
17.6
0.7
8.9
10.9
5.5
8.7
utant except
product
COD
69.0
81.5
1.4
30-
60
30-
50
35.1-
45
42.3
Wool
Total
Chrotni urn
0.05
0.07
—
0.05
0.05
.1 0.02
0.06
Scouring as kq(l
kkg {
Phenol
0.05
0.07
—
0.05
0.05
0.02
0.06
b) pollutant
1000 lb) raw
Sulfide
0.10
0.14
—
0.10
0.10
0.04
0.12
grease wool
Subcategory
Wool Scouring(2,4J
Wool Finishing (4)
Dry Processing (3)
Woven Fabric
Finishing (4)
Knit Fabric
Finishing (4)
Carpet Mills
Stock and Yarn
Dyeing and Finishing (4) 3.4
(1) Expressed as
and Carpet Mills as kg(1b) pollutant
kkg(1000 lb) primary backed carpet
(2) Oil and Grease Limitation for Wool Scouring is 3.6 kg(1b)
kKg(1000 lb) raw grease wool
(3) Fecal Coliform Limit for Dry Processing is 400 MPN per 100 ml.
(4) For those plants identified as Commission Finishers, an additional allocation of 100%
of the guidelines is to be allowed for the 30 day maximum levels.
-------
Ol
-P-
U
40
36
32
28
8 24
Q
| 30
LLJ
G! 16
U.
UJ
12
8
Figure 19
TYPICAL SEASONAL VARIATION
FOR BIOLOGICAL TREATMENT
SEASONAL VARIATION
WITHOUT CONTROL
D
CONTROLLED OPERATION X
MINIMUM OPERATIONAL CHANGE *
M
A
M
MONTH
O
IS!
D
-------
Ol
Ul
TABLE 20
PERFORMANCE OF BIOLOGICAL TREATMENT SYSTEMS
Plant
Code
J
K
L
M
N
0
P
Q
s
u
EE
GG
II
W
X
Y
Z
Waste
Character
Woven Fabric
Woven Fabric
Woven Fabric
Woven Fabric
Woven Fabric
Woven Fabric
Woven Fabric
Woven Fabric
Woven Fabric
Woven Fabric
Stock and Yarn
Stock and Yarn
Stock and Yarn
Knit Fabric
Knit Fabric
Knit Fabric
Knit Fabric
Production
1000 kg/day
(1000 Ib/day)
88 (194)
97 (214)
85.5 (190)
223.6 (493)
74.4 (164)
60.8 (134)
211 (466)
60 (133)
29.4 (65)
9.9 (22)
15.9 (35)
13.1 (28.9)
44.0 (96.5)
17.2 (37.8)
27.7 (61)
66.7 (147)
17.9 (39)
Influent BOD5
kg/1000 kg
Ob/1000 Ib)
66.0
22.2
108.0
40.6
66.2
40.0
138.0
52.3
49.3
20.9
38.7
47.2
14.9
49.8
19.0
80.3
16.6
BOD Removal
Efficiency
(Percent)
97.1
97.5
94.2
98.3
94.8
97.7
97.6
98.6
98.6
90.1
93.8
95.1
92.7
93.0
92.6
97.5
94.0
Average
51.2
95.5
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IDENTIFICATION OF BEST PRACTICABLE CONTROL
TECHNOLOGY CURRENTLY AVAILABLE
Best Practicable Control Technology Currently Available for the
textile manufacturing industry includes preliminary screening,
primary settling (wool scouring only) latex coagulation (carpet
mills and dry processing only) and secondary biological treatment.
Chlorination is included for dry processing mills only. Strict
management control over housekeeping and water use practices result
in raw wastes loads which can be treated biologically to the
effluent levels listed in Table 19. No special in-plant
modification is required. The performances of seventeen different
biological treatment systems that achieve these effluent limits are
given in Table 20.
Wool Scouring and Wool Finishing
The stated guidelines for subcategory 1 (wool scouring) and
subcategory 2 (wool finishing) can be achieved by applying the best
practicable control technology to the appropriate subcategory raw
waste load. The best practicable control technology for wool
scouring plants includes screening/ settling, and biological
treatment; best practicable control technology for wool finishing
plants includes screening and biological treatment. The recommended
effluent limitation guidelines for July 1, 1977, for the wool
scouring and wool finishing subcategories are based on results from
exemplary biological treatment systems (see Table 21 and 22) . These
systems treat textile waste waters from wool scouring and wool
finishing plants.
The effluent limitations for wool scouring plants (subcategory 1)
are calculated by data given in Table 21 for the full-scale
biological treatment system at mill A. Data from a pilot scale
project at mill B has not been used because of its limited
practicability. Data from a complete retainment system at mill AB
has not been used because the technology is limited to plants with
suitable and available land. A complete retainment system, however,
is a viable treatment alternative. The BOD5. , TSS and COD effluent
limitations are based on the average performance data from mill A
with an additional allowance of 50 percent to account for normal
operational variation. Thus, the BOD5 , TSS and COD limitations for
subcategory 1 plants are 5.3 kg/1000 kg (lb/1000 Ib), 16.1 kg/1000
kg (lb/1000 Ib) and 69.0 kg/1000 kg (lb/1000 Ib) of grease wool.
Results from 12 months (1973) of both warm and cold weather
operation at mill A indicates that occassional solids separation
problems have been experienced. Seven of forty-three sets of data
show TSS levels between 3,700 mg/1 and 8,400 mg/1. These results
are not representative of the performance that best practicable
technology should attain by 1977 and thus have been omitted from the
156
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TABLE 21
PERFORMANCE OF EFFLUENT TREATMENT SYSTEMS
SUBCATEGORY 1: Wool Scouring (1)
Plant
Code
A
B
AB
Av
Production
lOOOkg/day
(IQOOlb/day)
27 (60)
74.9 (165)
(2) 40.8 (90)
Average (A and B)
erage Plus 50 Percent
BODS Discharge
kg/lOOOkg
(Ib/lOOOlb)
3.5
2.4
0
3.0
4.5
TSS Discharge
kg/lOOOkg
(Ib/lOOOIb)
10.7
2.0
0
6.4
9.6
COD Discharge
kg/lOOOkg
(Ib/lOOOIb)
46.0
18
0
32.0
48.0
Grease Discharge
kg/lOOOkg
db/lOOOHj)
2.4
0.1
0
1.3
1.9
(1) Production and discharge quantities are recorded per weight
on raw grease wool as received and weighed at the plant.
(2) Total waste water containment (Not included in calculation of averages).
-------
TABLE 22
PERFORMANCE OF EFFLUENT TREATMENT SYSTEMS
SUBCATEGORY 2: Wool Finishing (1)
Plant
Code
C
D
Average
Average Plus
Production
lOOOkg/day
(lOOOlh/day)
12.7 (28)
38.6 (85)
50 Percent
BODS Discharge
(kg/lOOOkg)
(Ib/lOOOlb)
5.9
9.0
7.5
11.2
TSS Discharge
kg/lOOOkg
(Ib/lOOOlb)
9.7
13.7
11.7
17.6
COD Discharge
kg/lOOOkg
(Ib/lOOOlb)
44.0
64.6
54.3
81.5
£ (1) Production and Discharge Quantities are recorded per weight
00 of fiber as received and weighed at the plant.
-------
calculation in Table 21. The average concentration of the remaining
84 percent of the TSS data is 343 mg/1. Mills should be able to
maintain the required TSS levels throughout the year. In-plant
waste management, grease control, strict treatment operational
control and coagulant addition are possible solutions to solids
separation problems. Pilot plant results from mill B indicate TSS
levels can be consistently controlled at low levels.
Grease is a serious problem in the wool scouring subcategory.
Effluent levels observed especially at mill B indicate the grease is
recoverable and treatable to low levels. The effluent limitation
for grease is based on the grease discharge from mill A with an
additional allowance of 50 percent to account for normal operational
variation. Thus, the grease limitation for wool scouring plants is
3.6 kg/1000 kg (lb/1000 Ib) of grease wool.
The BOD5 and COD effluent discharges from mills A and B (Table 21)
are less than the respective BOD5 and COD effluent limitations. The
TSS and grease discharges from plant B are below the TSS and grease
effluent limitations.
The effluent limitations for wool finishing plants (subcategory 2)
are based on data from exemplary biological treatment systems
treating wool finishing wastes from plants C and D (Table 22). Both
of these plants average 50 percent or more wool and blended wool
products. The effluent guidelines for subcategory 2 are as follows:
BOD5 limitation is 11.2 kg/kkg (lb/1000 Ib); TSS limitation is 17.6
kg/kkg (lb/1000 Ib); and COD limitation is 81.5 kg/kkg (lb/1000 Ib).
Effluent limitations for subcategories 1 and 2 also include pH,
sulfide, phenol and total chromium limitations. Control of these
pollutants to the required levels is possible through well operated
biological treatment systems. The effluent limitations are based on
the mean water usage and effluent concentrations generally
attainable through biological treatment. The effluent limitations
are substantiated by water usage and waste water treatment data from
a study supported by the American Textile Manufacturers Institute,
Inc., and the Carpet and Rug Institute. The effluent limitations
for wool scouring plants (subcategory 1) are 0.05 kg/1000 kg
(lb/1000 Ib) for total chromium and for phenol and 0.10 kg/1000 kg
(lfa/1000 Ib) for sulfide. The effluent limitations for wool
finishing plants (subcategory 2) are 0.07 kg/1000 kg (lb/1000 Ib)
for total chromium and phenol and 0.14 kg/1000 kg/ (lb/1000 Ib) for
sulfide. Wool scouring and wool finishing plants should control pH
to within the range of 6.0 to 9.0.
Dry Processing
The stated guidelines for subcategory 3 (greige goods mills and
other dry processing operations) can be achieved by applying the
159
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best practicable control technology to the greige goods raw waste
load. The best practicable control technology include screening,
biological treatment and chlorination.
As described in Section III, dry processing operations include
manufacturers of greige goods, coated fabrics, laminated fabrics,
tire cord fabrics and felts, and carpet backing and carpet tufting.
The waste effluents from these operations should be less than 12.5
I/kg (1.5 gal/lb) of product as the principal source of effluent is
the washing and cleaning of equipment. Many mills discharge their
waste to sanitary systems. Of the mills that treat their own waste,
most combine their sanitary and industrial waste loads; the
respondees to an industry questionnaire indicated that 70 to 90
percent of the load was sanitary.
A compilation of water use figures for various textile subcategories
has been presented to EPA by the American Textile Manufacturers
Institute and the Carpet and Rug Institute. It appears to present
the full range of water uses to be expected for each subcategory.
The water use distribution for dry processing mills as shown in
Figure 20 illustrates an extremely wide variation. This can be
explained by the overriding influences of nonprocess water such as
boiler water, cooling water and sanitary wastes which are very
significant in some cases and less significant in others.
From the water usage distribution presented, it can be seen that the
median water use value is 7.5 I/kg (0.9 gal/lb) and the mean water
use value is 12.5 I/kg (1.5 gal/lb). This compares with 12.5 I/kg
(1.5 gal/lb) experienced by other segments of the subcategory and a
water use figure representative of industry performance. It has
been demonstrated that the BOD5_ from these dry processing operations
can be reduced to a low level. Because of this high treatability,
and the influence of sanitary waste, the best practicable control
technology should consistently attain 40 mg/1 BOD5 and 75 mg/1 COD.
The BOD5 and COD effluent limitations can be computed by applying
this concentration factor to the mean water usage and allowing a 50
percent increase to account for normal operations variation. Thus,
the BODS effluent limitation for dry processing (subcategory 3) is
0.7 kg/kkg(lb/10001b) of product and the COD effluent limitation is
1.4 kg/kkg (lb/1000 Ib) of product.
160
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TABLE 23
PERFORMANCE OF EFFLUENT TREATMENT SYSTEMS
SUBCATEGORY 3: Dry Processing (1)
Plant
Code
Production
lOOOkg/day
(IQOOlb/day)
33 (74)
BOD_5 Discharge
(kg/lOOOkg)
(Ib/lOOOlb)
0.02
TSS Discharge
kg/lOOOkg
(Ib/lOOOlb)
0.04
COD Discharge
kg/lOOOkg
(Ifa/lOOOlb)
0.29
(1) Plant I is a greige goods mill.
-------
(£
ill
w
cc
LU
10-1
X X
X X
MEDIAN
xx WATER USAGE = °'9 GAL/LB
xx
Figure 20
DISTRIBUTION OF WATER USE
FOR DRY PROCESSING
10-2
I II I I I I I I I II I
2 5 10
20 30 40 50 60 70 80
(PERCENT)
162
95 98
-------
The total suspended solids (TSS) effluent limitations are equivalent
to the BOD5 effluent limitations. Results from the exemplary
biological treatment systems indicated that TSS can be consistently
reduced to at least this level. Thus, the TSS effluent limitation
for dry processing is 0.7 kg/kkg (lb/1000 Ib) of product.
These BOD5, COD and TSS effluent limitations are substantiated by a
greige goods operation, plant I (Table 23). Two years of data
indicate a BOD5 and TSS effluent discharge of less than 0.1 kg/kkg
(lb/10001b) and COD discharge of less than 0.5 kg/kkg (lb/1CO Ib).
Effluent limitations for subcategory 3 (dry processing) also include
control of pH to within the range of 6.0-9.0 and chlorination to
control fecal coliforms to a level of 400 per 100 ml or less.
However, the fecal coliform limit will not apply if sanitary wastes
are not a constituent of a plant's final effluent.
Woven Fabric Finishing
The effluent guidelines for July 1, 1977, subcategory U (woven
fabric finishing) are the average of data from exemplary biological
systems treating wastes from the dyeing and finishing of broadwoven
cotton and cotton-synthetic blends. The BOD5 effluent limitation is
calculated from data tabulated in Table 24 from the average of the
BOD5 discharge from the biological treatment systems at Mills J, K,
L, N, O, P, Q, S, U and V and the TSS effluent limitation is based
on the average of treatment systems at Mills J, K, O, P, Q, S, and
V; and the effluent guidelines for subcategory 4 (woven fabric
finishing) are as follows: BOD5 limitation is 3.3 kg/kkg
(lb/10001b)and TSS limitation is 8.9 kg/kkg (lb/1000lb).
The exemplary BOD5 and TSS results from plant M have been omitted
from the calculations of BOD.5 and TSS effluent limitations because
these results are a reflection of biological treatment (BPCTCA) plus
the addition of powdered carbon. Total suspended solids limitations
have been computed without results from three plants (L,N, and U).
Biological treatment systems should be managed and operated in a
manner resulting in a TSS to BOD5 ratio of between one and two.
These three plants and a wool scouring plant discussed earlier have
experienced solids separation problems and their results are not
representative of the performance expected from best practicable
biological treatment systems in 1977. The TSS limitation is
sufficiently high that it should be achieved in a well designed,
163
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managed and operated biological treatment system with a final
clarifier.
Effluent data from the exemplary woven fabric finishing plants, as
well as other woven plant data was analyzed to determine whether the
fiber in use during the process or the complexity of the operation
had an impact on effluent quality. With respect to the total
suspended solids, (TSS), the data did not indicate a significant
influence on the results obtained. This is reasonable since, under
the definition of best practical control, clarification equipment
should be sufficient to control effluent suspended solids to the
levels described above. Similarly, the examination of BOD5 data
resulted in only a slightly greater impact of varying compositions
or process complexity on effluent concentrations. The groups of
plants which are identified to be exemplary include plants which
have manufacturing operations varying from simple to very complex.
The data from these plant treatment systems show the waste waters to
be treatable to the same quantitative degree (measured on a kg(Ib)
pollutant/kkg (1000 Ibs) product basis). For example, a simple
woven finishing plant employing cotton has an effluent BOD of 0.6
kg/kkg; a simple plant employing synthetic fibers has a final BOD of
0.9 kg/kkg; and two complex plants blending fibers have effluent
BOD's of 0.7 kg/kkg and 0.8 kg/kkg. (See Table 24.) Because the
value of BOD5 is essentially independent of the manufacturing
process, the level of BOD5 obtained by BPCTCA should approach the
equilibrium value of BODJ5 of the levels described above. Thus, the
BOD5 and TSS effluent levels are not substantially impacted by the
fiber or the process, but rather are impacted by waste treatment
design.
With respect to the COD that would be anticipated in the effluent, a
significant relationship was found between both the fiber employed
in the manufacturing process and the complexity of the process with
the resulting effluent strength. The basic assumptions in
determining the expected effluent levels of COD include an estimate
that the residual COD from the biodegradation of the degradable
organics plus the residual value of BOD5 would be equal to ten to
fifteen pounds of COD per 1,000 pounds of production. These values
are supportable from existing data. In addition, five to ten pounds
of this effluent COD would result from the fiber preparation step
after desizing but prior to dyeing. The cumulative effect of these
two phenomena would be to establish a COD of approximately 20 pounds
per 1,000 pounds of production. Ten Ibs per 1000 pounds of residual
COD are expected from the dyeing operations associated with basic
fabric finishing and when taken with the other processes establish
the minimum COD baseline of 30 pounds of non-degraded COD per 1000
pounds of product. When fibers are blended, allocation of an
additional 10 pounds of residual COD per 1000 pounds of product has
been demonstrated to be necessary because of additional dyeing steps
needed to achieve a uniform fabric color. Additionally, the use of
164
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TABLE 24
PERFORMANCE OF EFFLUENT TREATMENT SYSTEMS
SUBCATEGORY 4: Woven Fabric Finishing
Production
BOD5_ Discharge
TSS Discharge
COD Discharge
Plant
Code
J
K
L
N
0
P
Q
S
U
V
Average
Average Plus
lOOOkg/day
(lOOOlb/day)
88 (194)
97 (214)
85.5 (190)
74.4 (164)
60.8 (134)
211 (466)
60 (133)
29.4
9.9 (22)
56 (124)
50 Percent
kg/1000 kg
(lb/1000 Ib)
2.0
0.6
6.3
3.5
0.9
3.3
0.8
0.7
2.1
1.8
2.2
3.3
kg/ 1000 kg
(lb/1000 Ib)
3.4
0.8
23.8
23.0
9.9
13.6
6.7
4.8
21.7
2.2
5.9
8.9
kg/1000 kg
(lb/1000 Ib)
49.6
2.4
39.1
45.3
14.9
33.2
15.6
18.8
29.8
12.7
20 - 40
30 - 60
-------
synthetic fibers would add approximately ten pounds of COD per
thousand pounds of product. This discharge of ten pounds of COD per
1,000 pounds of production for synthetic fiber anticipates a
reduction of the synthetic sizing material during biological
treatment but envisions some residual. This contribution is
apparent when it is understood that approximately 40 to 50 pounds of
PVA or a similar size is utilized per thousand pounds of fabric
processed. Approximately ten pounds of additional COD is
anticipated from complex finishing operations such as printing or '
the like. Without additional treatment such as chemical coagulation
or activated carbon adsorption, obtaining values below these levels
appears to be impractical except in the cases of a few specific
manufacturing operations (i.e. denim production).
For purposes of the following discussion, a simple manufacturing
operation has been defined as the unit processes which include
desizing, fiber preparation and dyeing. Simple fabric finishing is
also included. Operations that require additional manufacturing
operations have been termed a complex manufacturing process. Unit
operations such as printing, functional fabric preparations,
including waterproofing, stain resistance, etc. would constitute
complex finishing operations.
In order to more clearly define the expected COD effluent levels,
the various process and fiber subdivisions are described below and
the resulting COD allowances listed in Table 25. The baseline
effluent level of COD described above (30 kg (Ib)/kkg (1000 Ib)
products) applies to simple manufacturing processes employing a
natural fiber. An allocation of 10 kg(Ib)COD/kkg (1000 Ib) product
to the baseline is allowed for simple manufacturing operations
employing a synthetic fiber, or complex finishing of a natural c
fiber. Simple manufacturing operations that are processing natural
and synthetic fiber blends and complex manufacturing operations that
process synthetic fiber are allowed an increment of 20 kg(lb) of COD *
per kkg (1000 Ibs) of product in excess of the baseline relating to
effects described above. For complex manufacturing operations using
natural and synthetic fiber blends, 30 kg(Ib) of COD per kkg (1000
Ibs) of product in excess of the baseline is established as the
allowable effluent COD level. When combinations of the above
classifications occur a prorated approach will be taken to establish
the allowable residual COD level.
166
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The matrix described above has been tested with existing plant data
from exemplary woven plants and other sufficiently similar plants.
The data generally agrees with those values presented above. The
effluent levels described above are the average for the subcategory
plus 50% to account for variability. Thus, the COD effluent
guidelines for subcategory U (woven fabric finishing) vary from 30
to 60 kg/kkg (lb/1000 Ib) .
The BOD5 effluent discharges from mills J, K, O, Q, S, U and V and
the TSS effluent discharges from mills J, K, Q, S, and V and the COD
effluent discharge for mills K, O/ P. Q, S, U and V are less than
the respective BOD5, TSS and COD effluent limitations. Mills K, Q,
S and V meet BOD5, TSS and COD effluent limitations. Mill M also
meets BOD5, TSS and COD effluent limitations.
Effluent limitations for woven fabric finishing plants (subcategory
H) also include pH, sulfide, phenol and total chromium limitations.
Control of these pollutants to the required levels is possible
through well operated biological treatment systems. The effluent
limitations are based on the mean water usage and effluent
concentrations generally attainable through biological treatment.
The effluent limitations are substantiated by water usage and waste
water treatment data from a study supported by the American Textile
Manufacturing Institute, Inc., and the Carpet and Pug Institute.
The effluent limitations are 0.05 kg/1000 kg (lb/1COC Ib) for -total
chromium and phenol and 0.1 kg/1000 kg (lb/1000 Ib) for sufide.
Woven finishing plants should control pH to within the range 6.0 to
9.0.
167
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TABLE 25
WOVEN FABRIC FINISHING
INTERNAL SOBCATEGOIRATION FOR
THE ESTABLISHMENT OF COD LIMITATIONS
COD COD
kg/kkg product kg/kkg product
(lb/1000 Ib product)) (lb/1000 Ib product
S^M..^* c.M.O**
Raw Material
Natural Fiber 30.0 UO.O
Synthetic Fiber 40.0 50.0
Natural and Synthetic 50.0 60.0
Fiber Blends
* S.M.O. - Simple manufacturing operation: shall mean all the
following unit processes: desizing, fiber
preparatipn, and dyeing from woven fabric
finishing. Simple fabric finishing is included.
** C.M.O. - Complex manufacturing operation: shall mean
"simple manufacturing operations" plus any
additional manufacturing operations such as
printing or functional fabric finishes such as
waterproofing, or treating for stain resistance,
for woven fabric finishing.
168
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Knit Fabric Finishing
The effluent guidelines for July 1, 1977 for subcategory 5 (knit
fabric finishing) are the average of data from exemplary biological
treatment systems. The BOD5 and TSS effluent limitations are
calculated from the average of the BOD5 and TSS discharges from the
biological treatment systems at Mills xT Y, and Z (see Table 26).
The BOD5 and TSS effluent limitations are based on these plants
allowing a 50 percent increase to account for treatment plant
variation: BOB5 is 2.5 kg/kkg (lb/10001b) and TSS is 10.9 kg/kkg
(lb/1000 Ib) .
Effluent data from the exemplary knit fabric finishing plants as
well as other knit plant data were analyzed to determine whether the
fiber in use during the process or the complexity of the operation
has an impact on the effluent quality. A rational was employed
similar to that described previously for woven fabric finishing
plants. The effluent levels for BOD5 and TSS were not substantially
impacted by either the fiber or the process, but rather were
impacted by waste treatment design. However, the COD was impacted
by both the fiber employed in the manufacturing process and the
complexity of the process.
For purposes of the above discussion, a simple manufacturing
operation has been defined as the unit processes which include
desizing, fiber preparation and dyeing. Simple fabric finishing is
also included. Operations that require additional manufacturing
operations have been termed a complex manufacturing process. Unit
operations such as printing, functional fabric preparation,
including waterproofing, stain resistance, etc. would constitute
complex finishing operations.
The basic assumption in determining the expected effluent levels of
COD include an estimate that the residual COD from biodegradation of
the degradable organics plus the residual value of COD would be
equal to 10 kg COD/1000 kg (Ib COD/1000 Ib) product each. These
values are supported from existing data. In addition, lubricants
associated with the knitting of fibers and the processes of
bleaching and/or single step dyeing will contribute about 10 kg(lb)
of COD per 1000 kg (1000 Ib) of product. Approximately 10 kg(lb) of
residual COD per 1000 kg (1000 Ib) of product is attributable to
complex manufacturing operations and an additional 10 kg(Ib) of non-
degraded COD must be allowed per 1000 kg(1000 Ib) of product for
duplicate dyeing necessary in manufacturing operations employing
natural and synthetic fiber blends.
In order to more clearly define the expected COD effluent levels,
the various process and fiber subdivisions are described below and
the resulting COD allowances listed in Table 27, The baseline
effluent level of COD described above (30 kg/kkg of product (lb/1000
169
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Ib of product) applies to simple manufacturing processes finishing
either natural or synthetic fibers and complex manufacturing
operations employing natural fibers. The finishing of synthetic
fiber in a complex manufacturing operation is allowed 10 kg of
COD/1000 kg of product (10 Ib COD/1000 Ib of product) in addition to
the baseline level. Blending of natural and synthetic fibers adds
10 kg/ COD/1000 kg of product in a simple manufacturing operation
and 20 kg of COD/1000 kg of product (Ib COD/1000 Ib product) to the
baseline of 30 kg of COD/1000 kg of product (Ib of COD/1000 Ib of
product) in a complex manufacturing operation. The matrix described
above has been tested with existing plant data from exemplary knit
plants and other sufficiently similar plants. The data generally
agrees with those values presented above. The effluent levels
described above ar.e the average for the subcategory plus 50% to
account for variability. Thus, the COD effluent limitations for
knit fabric finishing (subcategory 4) vary from 30 to 50 kg/kkg
(lb/1000 Ib). The BOD5, TSS and COD discharges from mills W, X, Y
and Z meet BOD5, TSS and COD effluent limitations.
Effluent limitations for knit fabric finishing plants (subcategory
5) also include pH, sulfide, phenol and total chromium limitations.
Control of these pollutants to the required levels is possible
through well operated biological treatment systems. The effluent
limitations are based on the mean water usage and effluent
concentrations generally attainable through biological treatment.
The effluent limitations are substantiated by water usage and waste
water treatment data from a study supported by the American Textile
Manufacturers Institute, Inc., and the Carpet and Rug Institute.
The effluent limitations are 0.05 kg/1000 kg (lb/1000 Ib) for total
chromium and phenol and 0.1 kg/1000 kg (lb/1000 Ib) for sulfide.
Knit finishing plants should control pH to within the range 6.0 to
9.0.
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TABLE 2
PERFORMANCE OF EFFLUENT TREATMENT SYSTEMS
SUBCATEGORY 5: Knit Fabric Finishing
Production
BODS Discharge
TSS Discharge
COD Discharge
Plant
Cede
W
X
Y
Z
Aver<
lOOOkg/day
(lOOOIb/day)
17.7 (38)
27.7 (61)
66.7 (147)
17.9 (39)
Average
age Plus 50 Percent
(kg/lOOOkg)
(Ib/lOOOIb)
3.0
0.7
2.0
1.1
1.7
2.5
kg/lOOOkg
(Ih/lOOOlb)
10.9
9.1
3.7
5.4
7.3
10.9
kg/10 00kg
(Ih/lOOOlb)
37.3
20.0
47.3
17.0
20 - 33
30 - 50
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TABLE 27
KNIT FABRIC FINISHING
INTERNAL SUBCATEGORIZATION FOR
THE ESTABLISHMENT OF COD LIMITATIONS
COD COD
kg/kkg product kg/kkg product
(lb/1000 Ib product)) (lb/1000 Ib product
S.M.O. * C-iMiO* *
Raw.Material
Synthetic Fiber 30.0 50.0
Natural and Synthetic 40.0 60.0
Fiber Blends
* S.M.O. - Simple manufacturing operation: shall mean all the
following unit processes: desizing, fiber
preparation, and dyeing from knit fabric
finishing. Simple fabric finishing is included.
** C.M.O. - Complex manufacturing operation: shall mean
"simple manufacturing operations" plus any
additional manufacturing operations such as
printing or functional fabric finishes such as
waterproofing, or treating for stain resistence,
for knit fabric finishing.
172
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f
Carpet Mills
The effluent guidelines for July 1, 1977 for subcategory 6 (carpets)
are the average of data from exemplary biological systems treating
carpet mill wastes. The BOD5, TSS and COD effluent limitations are
based on the average BOD5, TSS and COD discharges listed in Table 28
as kg (Ib) of pollutant per kg (Ib) of primary backed carpet (fiber
plus primary backing), for systems treating waste water from mills,
MC, BS, CC and BB. The effluent limitations for carpet mills
(subcategory 6) are as follows: BOD5 is 3.9 kg/kkg (lb/1000 Ib); TSS
is 5.5 kg/kkg (lb/1000 Ib); and COD~is 35.1 kg/kkg (lb/10CO Ib).
Production units are the weight of primary backed carpet.
Effluent data from the exemplary carpet mills as well as other
carpet data was analyzed to determine whether the fiber in use
during the process of the complexity of the operation had an impact
on the effluent quality. A rationale was employed similar to that
described previously for woven fabric finishing plants. The
effluent levels for BOD5 and TSS were not substantially impacted by
either the fiber or the process. The effluent COD was not
significantly impacted by the fiber type (most carpets are synthetic
fibers). However, the COD was impacted by the complexity of the
manufacturing process.
The effluent COD limitations determined from Table 28 is the
effluent COD resulting from a simple carpet manufacturing operation.
An additional COD increment of 10 kg/1000 kg (lb/1000 Ib) of primary
backed carpet must be allocated to complex manufacturing operations.
Thus, the COD effluent limitation for carpet mills range from 35.1
to 45.1 kg/kkg (lb/1000 Ib).
A simple manufacturing operation has been defined as the unit
„ processes which include fiber preparation, dyeing and carpet tufting
and backing. A complex manufacturing operation includes processes
requiring additional manufacturing operations. Unit operations such
as printing or dyeing plus printing would constitute a complex
finishing operation.
Effluent limitations for carpet mills (subcategory 6) also include
pH, sulfide, phenol and total chromium limitations. Control of
these pollutants to the required levels is possible through well
operated biological treatment systems. The effluent limitations are
based on the mean water usuage and effluent concentrations generally
attainable through biological treatment. The effluent limitations
are substantiated by water usage and waste water treatment data from
a study supported by the American Textile Manufacturers Institute,
Inc., and the Carpet and Rug Institute. The effluent limitations
are 0.02 kg/1000 kg (lb/1000 Ib) for total chromium and phenol and
0,04 kg/1000 kg (lb/1000 Ib) for sulfide. Carpet mills should
control pH to within the range 6.0 to 9.0.
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TABLE 28
PERFORMANCE OF EFFLUENT TREATMENT SYSTEMS
SUBCATEGORY 6: Carpet Mills
Production*
BODS Discharge
TSS Discharge
* Production given in weight of fiber plus primary backing.
COD Discharge
Plant
Code
MC
BS
CC
BB
lOOOkg/day
(IQQOlb/day)
8.2 (18.2)
30.2 (66.5)
98.3(216.6)
68.8(151.5)
Average
Average Plus 50 Percent
(kg/lOOOkg)
(Ib/lOOOlb)
4.8
2.9
1.4
1.4
2.6
3.9
kg/lOOOkg
. CLb/lOOOlb)
6.1
4.1
2.0
2.4
3.65
5.5
kg/lOOOkg
(lb/10'OOlb)
33.3
22.5
21.7
16.2
23.4
35.1
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Stock and Yarn Dyeing and Finishing
The effluent guidelines for July 1, 1977, for subcategory 7 (stock
and yarn) are the average of data from exemplary biological systems
treating wastes from dyeing and finishing stock and yarn. The BOD5,
TSS and COD effluent limitations are based on the average BOD£, TSS
and COD discharges listed in Table 29 for biological treatment
systems at Mills EE, GG and II. The effluent guidelines for
subcategory 7 are as follows: BOD5 limitation is 3.4 kg/kkg (lb/1000
Ib), TSS limitation is 8.7 kg7kkg (lb/1000 Ib), the COD effluent
limitation is 42.3 kg/kkg (lb/1000 Ib).
Effluent limitations for stock and yarn dyeing and finishing plants
(sutcategory 7) also include pH, sulfide, phenol and total chromium
limitations. Control of these pollutants to the required levels is
possible through well operated biological treatment systems. The
effluent limitations are based on the mean water usage and effluent
concentrations generally attainable through biological treatment.
The effluent limitations are substantial by water usage and waste
water treatment data from a study supported by the American Textile
Manufacturers Institute, Inc., and the Carpet and Rug Institute.
The effluent limitations are 0.06 kg/1000 kg (lb/1000 Ib) for total
chromium and phenol and 0.12 kg/1000 kg (lb/1000 Ib) for sulfide.
Stock and yarn finishing plants should control pH to within the
range 6.0 to 9.0.
Commission Finishing
The effluent guidelines for July 1, 1977, for subcategory 8
(commission finishing) are extrapolated from data from exemplary
biological systems treating waste from dyeing and finishing
operations. Commission houses exist in the wool scouring, wool
finishing, woven fabric finishing, and knit fabric finishing
sibcategories. The exemplary treatment plants in each of these
subcattgories have been used as a basis for developing effluent
limitations for commission finishing plants in the five
subcategories listed above. In recognition that biological
treatment may be more difficult and that the water usage and the raw
pollutant content for commission finishers may be much
(approximately 100 percent) greater than for normal or typical
finishing operations, the average BOD5, TSS and COD results from the
exemplary biological treatment plants for commission finishing in
the five subcategories listed above have been increased by 100
percent. Thus, the BODS, TSS and COD effluent limitations range
from 4.4-22.4 kg/kkg (lb/1000 Ib), 17.4-35.2 kg/kkg (lb/1000 Ib) ,
and 60-163 kg/kkg (lb/1000 Ib) respectively.
Effluent limitations for commission finishing plants also include
pH, sulfide, phenol and total chromium limitations. Control of
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these pollutants to the required levels is possible through well
operated biological treatment systems. The effluent limitations are
based on the mean water usage and the effluent concentration
generally attainable through biological treatment. The effluent
limitations are substantiated by water usage and waste water
treatment data from a study supported by the American Textile
Manufacturing Institute, Inc., and the Carpet and Rug Institute.
The effluent limitations range from 0.10-0.14 kg/1000 kg (lb/1000
Ib) for total chromium and phenol and 0,20-0.28 kg/1000 kg (lb/10CO
Ib) for sulfide. Commission finishing plants should control pH to
within the range 6.0 to 9.0.
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TABLE 29
PERFORMANCE OF EFFLUENT TREATMENT SYSTEMS
SUBCATEGORY 7: Stock and Yarn Dyeing
Production
BOD5 Discharge
TSS Discharge
COD Discharge
Plant
Code
EE
GG
11
A!
lOOOkg/day
(IQOQlb/day )
15.9 (35)
13.1 (28.9)
44.0 (96.5)
Average
/erage Plus 50 Percent
(kg/lOOOkg)
(Ib/lOOOlb)
3.6
2.3
1.1
2.3
3.4
kg/lOOOkg
(Ib/lOOOlb)
6.0
8.7
2.6
5.8
8.7
kg/lOOOkg
(Ib/lOOOlb)
-
28.2
—
28.2
42.3
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RATIONALE FOR THE SELECTION OF
BEST PRACTICABLE CONTROL TECHNOLOGY
CURRENTLY AVAILABLE
Age and Size of Equipment and Facility
The industry has generally modernized its plants as new methods that
are economically attractive have been introduced. No relationship
between age or size of production plant and effectiveness of its
pollution control was found.
Total Cost of Application in Relation to Effluent Reduction Benefits
Based on information contained in Section VIII of this report, the
estimated increase in final product costs required to achieve the
best practicable effluent reductions range, for small and large
plants in the eight subcategories, from 0.6 cents per kilogram
product (0.3 cents per pound product) to a high of 2.8 cents per
kilogram (1.2 cents per pound). The average price increase is 1.5
cents per kilogram (0.7 cents per pound).
Engineering Aspects of Control Technique Applications
The specified level of technology is practicable because it is being
practiced by plants representing a wide range of plant sizes and
types. Twenty-five exemplary biological treatment systems have been
utilized to develop the effluent limitations (see Tables 21-24, 26,
28 and 29) . These systems treat textile waste waters from wool
scouring and finishing, knit fabric finishing, dyeing and finishing
of broadwoven cotton and cotton-synthetic blends, carpet
manufacturing, and stock and yarn dyeing and finishing. The average
BOD5 removal efficiency of these systems is about 95 percent. In
the various subcategories there are additional treatment systems
that should be capable of meeting those limitations with some
modification in operation, perhaps the presence of a knowledgeable
operator. In general, some minor plant design changes along with
cooperation from management and plant personnel will be required.
Process Changes
Significant in-plant changes will not be needed by textile plants to
meet the specified effluent limitations. Some plants may need to
improve their water conservation practices and housekeeping, both
responsive to good plant management control.
Non-Water Quality Environmental Impact
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The major impact when the option of a biological treatment process
is used to achieve the limits will be the problem of sludge
disposal. Nearby land for sludge disposal may be necessary.
Properly operated biological systems would permit well conditioned
sludge to be placed in small nearby soil plots for drying without
great difficulty.
It is concluded that no new kinds of impacts will be introduced by
application of the best current technology.
Factors to be Considered in Applying BPCTCA Guidelines
1. Limitations are based on 30 day averages. Based on
performances of biological waste treatment systems, the
maximum daily limitations for BODj>,TSS,COD, oil and
grease, total chromium, phenol, and sulfide should not
exceed the 30 day average limitations by more than 100
percent. The maximum 30 day and daily limitations for
pH and fecal coliforms are identical.
2. If a plant produced materials in more than one
subcategory, for instance wool and synthetics, the
effluent limitations should be set by proration on the
basis of the percentage of fiber being processed to each
product.
3. Monitoring of total chromium, phenol and sulfide should
be conducted at a frequency less than BOD5, TSS or COD.
Monitoring of fecal coliforms may not be required if
sanitary wastes are not discharged in the plant
effluent.
4. These effluent limitations apply to a textile
installation processing a fiber or fabric through a
series of processes to a specific final product or
products. As such, the limitations are theoretically
intended to apply to all the unit processes performed at
a single mill. In a number of practical cases where
the processing and finishing operations are performed on
the same fiber or fabric at multiple mills, "double
counting" shall not be permitted but the production
shall be prorated as accurately as possible to each mill
in the overall process sequence.
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SECTION X
EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION OF
THE BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE
EFFLUENT LIMITATIONS GUIDELINES
INTRODUCTION
The effluent limitations which must be achieved no later than July
1, 1983, are not based on an average of the best performance within
an industrial category, but are determined by identifying the very
best control and treatment technology employed by a specific point
source within the industrial category and subcategory, or by one
industry where it is readily transferable to another. A specific
finding must be made as to the availability of control measures and
practices to eliminate the discharge of pollutants, taking into
account the cost of such elimination.
Consideration must also be given to:
The age of the equipment and facilities involved;
The process employed;
The engineering aspects of the application of various types
of control techniques;
Process changes;
The cost of achieving the effluent reduction resulting
from application of the technology;
Non-water quality environmental impact (including energy
requirements).
Also, Best Available Technology Economically Achievable emphasizes
in-process controls as well as control or additional treatment
techniques employed at the end of the production process.
This level of technology considers those plant processes and control
technologies which, at the pilot plant, semi-works, and other
levels, have demonstrated both technological performances and
economic viability at a level sufficient to reasonably justify
investing in such facilities. It is the highest degree of control
technology that has been achieved or has been demonstrated to be
capable of being designed for plant scale operation up to and
including "no discharge" of pollutants. Although economic factors
are considered in this development, the costs for this level of
control are intended to cover the top-of-the-line of current
technology, subject to limitations imposed by economic and
181
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engineering feasibility. However, there may be some technical risk
with respect to performance and with respect to certainty of costs.
Therefore, some industrially sponsored development work may be
needed prior to application of some of the technologies.
EFFLUENT REDUCTION ATTAINABLE THROUGH APPLICATION OF
THE BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE
Based on the information contained in Sections III through VIII of
this report, a determination has been made that the quality of
effluent attainable through the application of the Best Available
Technology Economically Achievable is as listed in Table 30. The
technology to achieve these goals is generally available, although
the advanced treatment techniques may not have yet been applied at
full scale to plants within each subcategory.
IDENTIFICATION OF THE BEST
AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE
Best available control technology economically achievable for the
textile manufacturing industry includes the preliminary screening,
primary settling (wool scouring only), coagulation (carpet mills
only), secondary biological treatment and chlorination (dry
processing only) listed under the Best Practicable Control
Technology Currently Available. In addition, it includes additional
treatment techniques such as multi-media filtration and chemical
coagulation/clarification following biological treatment.
Chlorination for all subcategories is included.
Management controls over housekeeping and water use practices will
be stricter than required for 1977. However, no additional in-plant
controls will be required to achieve the specified levels of
effluent reduction. There are several in-plant controls and
modifications that provide alternatives and trade-offs to additional
effluent treatment. For example, a scouring bowl train designed for
complete counter-current operation can significantly reduce water
usage at wool scouring facilities.
In Section IX, the maximum 30 day effluent limitations were
calculated by applying a factor of 50 percent to the pollutant
discharge quantities from the exemplary treatment systems to account
for the natural variation in effluent quality from a biological
treatment plant. The maximum daily limitations were calculated by
applying a factor of 100 percent to the maximum 30 day limitations
to account for the inherent variation in pollutant load from the
manufacturing facilities. The best available control technology
includes better in-plant waste management practices, improved
biological treatment operation, and additional treatment processes
(filtration and chemical treatment) so that the variability
associated with the biological treatment facilities should be
182
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minimal. However, the variability associated with the manufacturing
facility cannot be significantly controlled by these treatments and
controls. Thus, the factor of 50 percent is not needed to calculate
maximum 30 day limitations but the factor of 100 percent is still
required to calculate the maximum day limitations.
Multi-media filtration and chemical coagulation/clarification have
been demonstrated at a few textile mills as well as plants in other
industrial categories. Multi-media filtration has been shown to
consistently remove TSS to a level between 5-8 mg/1. A TSS level
of 10 mg/1 has been used below to calculate TSS discharge limits.
Chemical coagulation/clarification has been shown to remove over 50
percent of the COD in applications in the textile and pulp and paper
industries. A COD removal efficiency of 50 percent has been
utilized below to calculate COD effluent limitations.
BATEA effluent limitations for wool scouring plants sutcategory are
based on an optimized treatment system including a hot acid cracking
process for grease removal and a biological treatment system. The
model system is similar to that demonstrated on a pilot scale at
plant B (see Table 21). The effluent limitations for BOD5, TSS and
COD are modeled after this plant and are as follows: 2.4 kg/kkg
(lb/1000 Ib) for BOD5; 2.0 kg/kkg (lb/1000 Ib) for TSS; and 18
kg/kkg (lb/1000 Ib) for COD. Grease limitations based on this
system are 1.0 kg/kkg (lb/1000 Ib). BATEA effluent limitations for
wool finishing plants (subcategory 2) are based on BPCTCA plus
multi-media filtration and chemical coagulation/clarification. The
BODJ5 effluent limitation is based on the water usage demonstrated by
mill G, a wool finishing mill - 247 I/kg (30 gal/lb) of dry wool
fiber. This water usage figure is applied to the current water
usage of exemplary mills C and D to calculate their respective BOD
discharges. The effluent BOD limitation is the average of the
present BOD concentration values from mills C and D. A water usage
of 247 I/kg (30 gal/lb) and a concentration of 10 mg/1 of TSS has
been used to calculate the TSS limitation. The COD limitations are
based on a fifty percent reduction of the COD discharge from
exemplary plants C and D (Table 22). This reduction should be
consistently achieved through filtration and coagulation. The
effluent limitations for BOD5, TSS and COD are as follows: 4.6
kg/kkg (lb/1000 Ib) for BOD5; 2.5 kg/kkg (lb/1000 Ib) for TSS; and
27.1 kg/kkg (lb/1000 Ib) for COD.
BATEA, for dry processing operations (subcategory 3) is BPTCA plus
multi-media filtration. Limitations are substantiated by the
demonstrated results from exemplary plant I (See Table 23) and data
supplied through the American Textile Manufacturers Institute and
the Carpet and Rug Institute. The BODJ5, TSS and COD effluent
limitations are as follows:0.2 kg/kkg (lb/1000 Ib) for BOD; 0.2
kg/kkg (lb/1000 Ib) for TSS; and 0.4 kg/kkg (lb/1000 Ib) for COD.
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BATEA limitations for woven fabric finishing plants (subcategory 4)
are based on BPCTCA plus multi-media filtration and chemical
coagulation/clarification. The BOD5 effluent limitation is based
on results tabulated in Table 24. The BOD5 limitation is the
average BOD5 from the exemplary plants. The COD effluent
limitations are based on the complexity and fiber composition
factors developed in Section IX, although the factor for variability
due to the biological treatment system has been removed. The BATEA
limitations are 50 percent of these values due to the advanced
treatment. These effluent levels should be consistently achieved
through BPCTCA plus filtration and coagulation. The TSS limitation
is based on the mean water usage of 29 woven plants (149 I/kg or
18.1 gal/lb) and a concentration of 10 mg/1. Multi-media filtration
should deliver an effluent with a TSS of 5-8 mg/1. Thus, the BOD5,
TSS and COD effluent limitations are 2.2 kg/kkg (lb/100C Ib) for
BOD5, 1.5 kg/kkg (lb/1000 Ib) for TSS and 10.0 to 20.C kg/kkg
(lb/1000 Ib) for COD.
BATEA limitations for knit fabric finishing plants (subcategory 5)
are based on BPCTCA plus multi-^media filtration and chemical
coagulation/clarification. The BOD5 effluent limitation is based
on results tabulated in Table 26. The BOD5 limitation is the
average BOD5 from the exemplary plants. The COD effluent
limitations are based on the complexity and fiber composition
factors developed in Section IX, although the factor for variability
due to the biological treatment system has been removed. The BATEA
limitations are 50 percent of these values due to the advanced
treatment. These effluent levels should be consistently achieved
through BPTCA plus filtration and coagulation. The TSS limitations
are based on the mean water usage of 18 knit plants (166 I/kg or
20.2 gal/lb) and a concentration of 10 mg/1. Multi-media filtration'
should deliver an effluent with a TSS of 5-8 mg/1. Thus, the BODj>,
TSS and COD effluent limitations are 1.7 kg/kkg (lb/1000 Ib) for
BOD5, 1.7 kg/kkg (lb/1000 Ib) for TSS and 10.0 to 16.7 kg/kkg
(lb/1000 Ib) for COD.
BATEA limitations for carpet mills (subcategory 6) are based on
BPCTCA plus multi-media filtration and chemical
coagulation/clarification. The BOD5 effluent limitation is based
on results tabulated in Table 28. The BOD5 limitation is the
average BOD5 from the exemplary plants. The COD effluent
limitations are based on the manufacturing complexity factor in
Section IX, although the factor for variability due to the
biological treatment system has been removed. The BATEA limitations
are 50 percent of these values due to the advanced treatment. These
effluent levels should be consistently achieved through BPCTCA plus
filtration and coagulation. The TSS limitation are based on the
mean water usage of 38 carpet mills (62 I/kg or 7.5 gal/lb) and a
concentration of 10 mg/1. Multi-media filtration should deliver an
effluent with a TSS of 5-8 mg/1. Thus, the BOD5, TSS and COD
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effluent limitations are 2.0 kg/kkg (lb/1000 Ib) for BOD5, 1.0
kg/kkg (lb/1000 Ib) for TSS and 11.7 to 15 kg/kkg (lb/1000 Ib) for
COD.
BATEA limitations for stock and yarn dyeing and finishing plants
(subcategory 7) are based on BPCTCA plus multi-media filtration and
chemical coagulation/clarification. The BOD5 and COD effluent
limitations are based on results tabulated in Table 29. The BOD5_
limitation is the average BOD5 from the exemplary plants and the COD
limitation is 50 percent of the average COD from the exemplary
plants. These effluent levels should be consistently achieved
through BPTCA plus filtration and coagulation. The TSS limitations
are based on the mean water usage of 27 subcategory 7 plants (183
I/kg or 22.3 gal/lb) and a concentration of 10 mg/1. Multi-media
filtration should deliver an effluent with a TSS of 5-8 mg/1. Thus,
the BOD.5, TSS and COD effluent limitations are 2.3 kg/kkg (lb/1000
Ib) for BOD5, 1.9 kg/kkg (lb/1000 Ib) for TSS and 14.1 kg/kkg
(lb/1000 Ib) for COD.
BATEA limitations for commission finishers in four subcategories
(wool scouring, wool finishing, woven fabric finishing and knit
fabric finishing) are based on BPCTCA plus multi-media filtration
and chemical coagulation/clarification. As in Section IX, the
exemplary treatment plants in each of the subcategories has been
used as a basis for developing the effluent limits for commission
finishing. The BATEA limitations for each of these four
subcategories have been increased by 100 percent for commission
finishing to account for their higher water and waste loadings and
their difficulty of treatment. Thus, the BOD5, TSS and COD effluent
limitations for commission finishing in the five subcategories range
from 2.6-9.2 kg/kkg (lb/1000 Ib), 3.0-5.0 kg/kkg (lb/1000 Ib) and
20-^54.2 kg/kkg (lb/1000 Ib) respectively.
BPCTCA effluent limitations for phenol, total chromium and sulfide
are included in the BATEA limitations for appropriate subcategories
as described in Section IX. Fecal coliform limits of 400 per 100 ml
MPN are also included in each subcategory as BATEA effluent
limitations. pH between 6-9 is also included for all subcategoies
as BATEA. The data base for the limitation is such that the Agency
recognizes these color limits may need substantial revision prior to
the implementation of BATEA guidelines. The limits are 600 ADMI
units for wool scouring and wool finishing plants (subcategores 1
and 2) , 300 ADMI units for woven and knit fabric finishing, and
stock and yard dyeing and finishing subcategories (subcategories
4, 5, and 7) and 225 ADMI units for carpet mills (subcategory 6).
Limits vary from 600 to 1200 ADMI units for commission finishers in
the five subcategories listed above. No limits are required for dry
processing operations (subcategory 3). See Appendix A for the
analytical procedure and the calculations required to test for
color.
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Table 30
Maximum Thirty Day Average
Effluent Limitations Guidelines (1)
for July 1, 1983
Subcategory
Wool Scouring (3
Wool Finishing
Dry Processing
Woven Fabric
Finishing (4)
Knit Fabric
£ Finishing (4)
OS
Carpet Mills
Stock and Yarn
Dyeing and
Finishing (4)
BODS
,4) 2.4
(4) 4.6
0.2
2.2
1.7
2.0
2.3
TSS
2.0
2.5
0.2
l.b
1.7
1.0
1.9
COD
lb.0
27.1
0.4
10.0-
20.2
10.0-
16.7
11.7-
15.0
14.1
Total
Chromium
U.Ob
0.07
0.05
0.05
0.02
0.06
Phenol
0.05
0.07
0.05
0.05
0.02
0.06
Sulfide
0.10
0.14
0.10
0.10
0.04
0.12
Fecal
Col i form
MPN
4uO 100ml
MPN
4UO 100ml
MPN
400 lOOnil
MPM
400 100ml
MPN
40U 100ml
MPN
400 100ml
MPN
400 100ml
Color (z)
600
600
—
300
300
225
300
(1) Expressed as kg (Ib) pollutant except Wool Scouring as kg (1b) pollutant
kkg (lOOO Ib) product kkg (lOOO lb) raw grease wool
and Carpet Mills as kg (lb) pollutant
kkg (1000 Ib) primary backed carpet
(2) Color in APHA units
(3) Oil and Grease limitations for Wool Scouring is 1.0 kg (Ib)
kkg (1000 lb) raw grease wool
(4) For those plants identified as Commission Finishers, an additional allocation of 100% ot the guidelines
is to be allowed for the 30 day and maximum levels.
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RATIONALE FOR THE SELECTION OF BEST
AVAILABLE CONTROL TECHNOLOGY ECONOMICALLY ACHIEVABLE
Age and Size of Equipment and Facilities
The industry has generally modernized its plants as new methods that
are economically attractive had been introduced. No relationship
between age or size of production plant and effectiveness of its
pollution control was found.
Total Cost of Application in Relation to Effluent Reduction Benefits
Based on information in Section VIII of this report, the estimated
additional increase in final product costs required to achieve
effluent reductions through the application of the best available
technology range, for small and large plants in the eight
subcategories, from 0.7 cents per kilogram (0.3 cents per pound) of
product to 7.3 cents per kilogram (3.2 cents per pound) of product.
The average additional price increase is 2.3 cents per kilogram (1.0
cents per pound of product).
Engineering Aspects of Control Technique Application
The specified level of technology is achievable. Biological
treatment is practiced throughout the textile industry; its
effectivenss is demonstrated in Tables 21-24, 26, 28 and 29.
Chemical coagulation has been studied for textile waste treatment
for over 20 years. It has been successfully demonstrated at three
mills although its effectiveness has not been demonstrated in all
textile subcategories. The best available limits for BOD5, TSS and
COD are being met by a subcategory H plant K and the BOD5 and COD
limits are being met by plants M, Q, S, and V. An alternative to
chemical coagulation is activated carbon. Although somewhat more
expensive, the waste water benefits from activated carbon can
justify carbon at many larger textile plants. It may be especially
attractive to new textile plants. Ozonation may also be an
alternative.
Filtration is the most common form of advanced waste water treatment
because of its relatively inexpensive nature and its effectiveness
in removing suspended solids and the organics associated with the
solids. Multi-media filtration has been used effectively in various
EPA applications including Lebanon, Ohio, and Washington, D.C.
Filtration has been demonstrated with full-scale units at at least
two textile mills and another plant is currently installing
filtration equipment.
187
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Process Changes
No in-plant changes will be needed by most plants to meet the limits
specified. Some in-plant techniques are available as alternatives
to effluent treatment techniques.
Non-Water Quality Environmental Impact
The non-water quality environmental impacts will essentially be
those described in Section IX. Additional solid waste impacts may
result from the waste sludge generated from chemical~ coagulation.
However, these wastes are handled effectively in sanitary landfills.
Thus, it is concluded that no new serious impacts will be
introduced.
Factors to be Considered in Applying BATEA Guidelines
1. Limitations are based on 30 day averages. Based on
performances of biological waste treatment systems, the
maximum daily limitations for BOD5, TSS, COD and oils
and grease should not exceed' the 30 day average
limitations by more than 100 percent. The maximum 30
day and daily limitations for pH and fecal coliforms are
identical.
2. If a plant produced materials in more than one
subcategory, for instance wool and synthetics, the
effluent limitations should be set by proration on the
basis of the percentage of fiber being processed to each
product.
3. Monitoring of total chromium, phenol and sulfide should
be conducted at a frequency less than BOD5, TSS or COD.
Monitoring of fecal coliforms may not be required if
sanitary wastes are not discharged in the plant
effluent.
4. These effluent limitations apply to a textile
installation processing a fiber or fabric through a
series of processes to a specific final product or
products. As such, the limitations are theoretically
intended to apply to all the unit processes performed at
a single mill. In a number of practical cases where
the processing and finishing operations are performed on
the same fiber or fabric at multiple mills, "double
counting" shall not be permitted but the production
shall be prorated as accurately as possible to each mill
in the overall process sequence.
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SECTION XI
NEW SOURCE PERFORMANCE STANDARDS
INTRODUCTION
The effluent limitations that must be achieved by new sources are
termed performance standards. The New Source Performance Standards
apply to any source for which construction starts after the
publication of the proposed regulations for the Standards. The
Standards are determined by adding to the consideration underlying
the identification of the Best Practicable Control Technology
Currently Available, a determination of what higher levels of
pollution control are available through the use of improved
production processes and/or treatment techniques. Thus, in addition
to considering the best in-plant and end-of-process control
technology, New Source Performance Standards are based on an
analysis of the process itself. Alternative processes, operating
methods or other alternatives are considered, However, the end
result of the analysis is to identify effluent standards which
reflect levels of control achievable through the use of improved
production processes (as well as control technology), rather .than
prescribing a particular type of process or technology which must be
employed. A further determination made is whether a standard
permitting no discharge of pollutants is practicable.
Consideration must also be given to:
Operating methods;
Batch, as opposed to continuous, operations;
Use of alternative raw materials and mixes of raw materials;
Use of dry rather than wet processes (including substitution
of recoverable solvents for water) ;
Recovery of pollutants as by-products.
EFFLUENT REDUCTION ATTAINABLE FOR NEW SOURCES
The effluent limitation guidelines for new sources are based on the
Best Practical Control Technology Currently Available plus multi-
media filtration (Table 31) . This limitation is achievable in newly
constructed plants. In-plant controls and waste treatment
technology identified in Section IX are available now and applicable
to new plants.
RATIONALE FOR THE SELECTION OF NEW SOURCF PERFORMANCE STANDARDS
new source technology includes the technology identified in
Section IX: preliminary screening, primary settling (wool scouring
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only), coagulation (carpet mills only) , and biological treatment.
It also includes multi-media filtration which has been demonstrated
at a few textile mills as well as in many other industries. The TSS
limits are such that in many cases they can be achieved with a well
designed and well operated biological treatment system. In some
cases, chemical addition may be needed in the final clarifier and in
a few cases, multi-media filtration may be required. Because most
plants will be able to attain these standards without significant
additions to the best practicable control technology, the general
conclusion reached in Section IX with respect to Total Cost of
Application in Relation to Effluent Reduction Benefits, the
Engineering Aspects of Control Technique Application, Process
Changes, Non-Water Quality Environmental Impact and Factors to be
Considered in Applying BPCTCA Guidelines, apply with equal force to
those New Performance Standards.
ENGINEERING ASPECTS AND COSTS OF APPLICATION IN RELATION TO EFFLUENT REDUCTION BENEFITS
However, the cost and engineering conclusions require additional
explanation. The average final product cost increase associated
with biological treatment and multi-media filtration for both small
and large plants in the eight subcategories is projected to be 2.3
cents per kilogram product (1.0 cents per pound product). This
compares with an average cost increase associated with biological
treatment alone of 1.5 cents per kilogram (0.7 cents per pound).
The availability of multi-media filtration also requires
explanation. Filtration is the most common form of advanced waste
water treatment because of its relatively inexpensive nature and its
effectiveness in removing suspended solids and the organics
associated with the solids. Multi-media filtration has been used
effectively in various EPA applications and at least two textile
mills. Another mill is currently installing filtration. The TSS
new source standards are currently being achieved with biological
treatment plants without filtration at seven mills in five
subcategories. Thus, multi-media filtration will consistently
achieve new source TSS standards, and a well designed and operated
biological treatment system is also capable of achieving the
standards.
PRETREATMENT REQUIREMENTS
Several constituents of the waste water from plants within the
textile industry have been found which would interfere with, pass
through, or otherwise be incompatible with a well designed and
operated publicly owned activated sludge or trickling filter waste
water treatment plant. Waste water constituents include grease from
wool scouring operations, COD, total chromium, phenol and sulfide.
Adequate control methods can and should be used to keep significant
quantities of these materials out of the waste water. Dye
substitutes are available for many dyes containing heavy metals.
190
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Table 31
Maximum Thirty Day Average
Effluent Limitations Guidelines (1)
for New Sources
Subcategory
Wool Scouring(2,4)
Wool Finishing (4)
Dry Processing (3)
Woven Fabric
Finishing (4)
Knit Fabric
Finishing (4)
Carpet Mills
Stock and Yarn
Dyeing and Finishing (4) 3.4
BOD5
5.3
11.2
0.7
3.3
2.5
3.9
3.4
TSS
5.3
11.2
0.7
3.3
2.5
3.9
3.4
COD
69.0
81.5
1.4
30-
60
30-
50
35.1-
45.1
42.3
Total
Chromi urn
0.05
0.07
0.05
0.05
0.02
0.06
Phenol
0.05
0.07
0.05
0.05
0.02
0.06
Sulfide
0.10
0.14
0.10
0.10
0.04
0.12
(1) Expressed as kg Mb) pollutant except Wool Scouring as kg fib) pollutant
kkg(1000 Ib) product kkg (1000 Ib) raw grease wool
and Carpet Mills as kg Mb) pollutant
kkg(1000 Ib) primary backed carpet
(2) Oil and Grease Limitation for Wool Scouring is 3.6 kg (Ib)
kkg(1000 Ib) raw grease wool
(3) Fecal Coliform Limit for Dry Processing is 400 MPN per 100 ml.
(4) For those plants identified as Commission Finishers, an additional allocation of 100%
of the guidelines is to be allowed for the 30 day maximum levels.
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SECTION XII
ACKNOWLEDGMENTS
Special thanks and appreciation are due the following manufacturing
organizations: The American Textile Manufacturers Institute; The
Northern Textile Association; The Carpet and Bug Institute; and
The American Association of Textile Chemists and Colorists.
Appreciation is expressed for the interest of several individuals
within the Environmental Protection Agency: W. H Cloward, Region IV;
Thomas Sargent, SERL, Athens, Georgia; Edmund Struzeski, NFIC, Denver,
Colorado; Charles Ris, 0 R & D; Richard Sternberg, Mark Moser, William
Hancuff, John Riley, George Webster, Ernst Hall, Allen Cywin, EGD.
Thanks are also due the many secretaries who typed and retyped this
document: Acqua Dulaney, Pearl Smith, Karen Thompson, Jane Mitchell,
and Barbara Wortman.
Special acknowledgment is made of the contributions of industry
personnel who provided information to the study. Their active response,
cooperation and assistance is greatly appreciated.
193
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SECTION XIII
REFERENCES
A review of the recent literature for references on Textile wastes and
waste treatment has produced over 200 references. Brief abstracts of
50 of these references are included as well as the full list of references.
(2) "The BOD of Textile Chemicals, Updated List - 1966"
American Dyestuff Reporter, (55) No. 18, 39-42, 1966.
(self-explanatory)
(15) "What the Mills are Doing to Control Water Pollution"
Textile Chemist and Colorist, (1) No. 6, 25-36, 1969.
This article gives a brief rundown of waste control activities at:
1. American Enka, N.C. facility, where rayon, nylon, and
polyester are produced
2. Burlington Industries (general)
3. Cannon Mills (discussed new design in detail)
4. cone Mills (general)
5. Dan River Mills (Danville plant)
6. M. Lowenstein & Sons (Lyman Printing and Finishing Co.)
(18) Molvar, A., C. Rodman, and E. Shunney
"Treating Textile Wastes with Activated Carbon"
Discusses activated carbon treatment in general, pilot plant
work, and actual operating data for a full size waste treatment
system. The mill's identity is not given (dyeing and finishing).
(21) Souther, R.H.
"Waste Treatment Studies at Cluett, Peabody & Company Finishing Plant"
American Dyestuff Reporter, (58) No. 15, 13-16, 1969.
Detailed operating data on the Arrow Co., Division at Waterford, New
York. The treatment system consists of an "extended-contact,
activated sludge step, bio-aeration process." Also includes caustic
recovery.
195
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(22) "Wastewater Treatment Recycles 80 Percent of Industrial Flow"
American Textile Reporter, (83) No. 51, 14-15, 1969.
Very brief description and general flow diagram of the waste treat-
ment system using activated carbon at Hollytex Carpet Mills (near
Philadelphia). No real operating data is given.
(25) Jones, E.L., T.A. Alspaugh, and H.B. Stokes
"Aerobic Treatment of Textile Mill Waste"
JWPCF (34) No. 5, 495-512, 1962.
Cone Mills, joint treatment of mill and municipal sewage by
contact stabilization process. (Pilot plant operating data.)
(47) poon, C.P.C.
"Biodegradability and Treatability of Combined Nylon and
Municipal Wastes"
JWPCF (42) No. 1, 100-105, 1970.
Treatability study of wastes taken from the fielding Chemical Co.
in Thomaston, Connecticut. Strictly a laboratory study.
(49) Kwie, W.W.
"Ozone Treats Wastestreams from Polymer Plant"
Water and Sewage Works, 116, 74-78, 1969.
Laboratory study on ozone treatment of wastes from polymer plant
(including SANS). The study did not produce very satisfying results.
(52) Wheatland, A.B.
"Activated Sludge Treatment of Some Organic Wastes"
Proc. 22nd Ind. Waste conf. Purdue Univ. 983-1008, 1967.
Treatability study on a simulated synthetic fiber production and
dyeing waste using a bench scale activated sludge unit.
(53) carrigue, C.S., and L.U. Jauregui
"Sodium Hydroxide Recovery in the Textile Industry"
Proc. 22nd Ind. Waste Conf. Purdue Univ., 1966.
Castelar Textile Mill, Argentina (cotton goods)
Description of NaOH recovery from the mercerizing process. NaOH
is filtered and then concentrated by evaporating. Design criteria,
operating data and capital and operating costs are given.
(56) Taylor, E.F., G.C. Gross, and R.F. Rocheleau
"Biochemical Oxidation of Wastes from the New Plant for Manufacturing
Orion at Waynesboro, Va."
Proc. 15th Ind. Waste Conf. Purdue Univ., 1961.
196
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Detailed description of Dupont's Waynesboro works. Waste facilities
consist of a catalytic oxidation unit which completely oxidizes the
organics associated with the recovery of dimethylformamide and an
activated sludge unit for treatment of dilute organic materials such
as acrylonitrile, dimethylformamide and formic acid.
(57) Sadow, R.D.
"The Treatment of Zefran Fiber Wastes" (acrylic fiber)
Dow Chemical Company's Williamsburg, Va., plant. Description of
waste treatment process which includes primary settling, chemical
coagulation, a Dowpac oxidation tower, and secondary settling.
Operating data and design criteria are given.
(61) Jones, L.L.
"Textile Waste Treatment at Canton Cotton Mills"
JWPCF (37) No. 12, 1693-1695, 1965.
Gives a rather brief description of their activated sludge unit with
design criteria, operating data (sketchy) and cost information.
(62) Smith, A.L.
"Waste Disposal by Textile Plants"
JWPCF (37) No. 11, 1607-13, 1965.
Very general article, gives some synthetic textile waste characteris-
tics and very brief descriptions of waste characteristics and treat-
ment methods at:
1. Chatham Manufacturing Co., Elkin, N.C. (multi-fiber woolen mill)
2. J.P. Stevens Co., Wallace Plant
(63) Dean, B.T.
"Nylon Waste Treatment"
JWPCF (33) No. 8, 864^70, 1961.
Operating experience of the Chemstrand Corp. Pensacola plant which
utilizes an activated sludge unit followed by a post-treatment lagoon.
(76) Suchecki, S.M.
"A Dyer's "Operation Cleanup"
Textile Industries (130) No. 6, 113, 1966.
Description of Northern Dyeing Co., Washington, N.J. treatment
facilities. Very little operating data given.
(86) Souther, G.P.
"Textile Water Pollution Woes Can be Resolved by Solvents"
American Textile Reporter (5U) No. 9, 11, 13, 1970.
197
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Describes solvent sizing and dyeing processes. This is an infor-
mative but not very detailed article.
(95) Porter, J.J.
"Concepts for Carbon Adsorption in Waste Treatment"
Textile Chemists and Colorists (4) No. 2, 29-35, 1972.
The history of carbon's entry into the waste treatment field is
presented. Interpretations of the fundamental kinetics and
thermodynamics of carbon adsoption are also given with several
specific examples cited.
(99) Podman, C.A.
"Removal of Color from Textile Dye Wastes"
Textile Chemists and Colorists (3) No. 11, 239-47, 1971.
Solutions of four types of dyestuffs were treated by several methods
that have been used practically or experimentally for color removal.
Among these were coagulation by lime and by alum; extended aeration,
activated carbon adsorption, reverse osmosis, and treatment with high
pressure oxygen and cobalt-60 radiation.
(100) Rhame, G.A.
"Aeration Treatment of Textile Finishing Wastes in South Carolina"
American Dyestuff Reporter (60) No. 11, 46, 1971.
Operating data of several unidentified plants is presented along
with general design criteria.
(103) Porter, J.J.
"Treatment of Textile Waste with Activated Carbon"
American Dyestuff Reporter (61) No. 8, 24-7, 1972.
Considerations in evaluating the potential application of carbon
adsorption to a waste stream are discussed along with procedures
for conducting laboratory studies.
(106) Stone, R.
"Carpet Mill Industrial Waste System"
JWPCF (44) No. 3, 470-478, 1972.
A description of the waste treatment system of the Walter Carpet
Mill, City of Industry, California is presented.
(108) Little, A.H.
"Use and Conservation of Water in Textile Processing"
Journal of the Society of Dyers and Colorists (87) No. 5, 137-45, 1971
Investigation of water usages in unit processes under normal pro-
198
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duction conditions. The effects of different dyeing and bleaching
processes have been studied. Possible methods of conservation of
water are discussed, including Contra-flow washing. In addition,
the effects of changes in processing, the size, type and speed of
machines and the effects of cloth weight and batch size are discussed.
(110) Masseli, J.W., N.W. Massell, and M.C. Burford
"Factors Affecting Textile Waste Treatability"
Textile Industries for October 1971, p. 84-117
General design parameters of activated sludge waste treatment are
discussed along with startup and operational considerations. Waste
contributions (in terms of % total BOD) are given for the individual
process chemicals used in a typical cotton mill, cotton/synthetic
mill, and woolen mill.
(Ill) Shunney, E.L., Perratti, A.E., and Rodman, C.A.
"Decolorization of Carpet Yarn Dye Wastewater"
American Dyestuff Reporter (60) No. 6, 32-40, 1971.
Laboratory and full-scale operation of bio-regenerated activated
carbon treatment of carpet yarn fiber dyeing are discussed. The
facility described is the C. H. Masland & Sons plant in Wakefield,
Rhode island.
(113) Rodman, C.A./ and E. L. Shunney
"A New Concept for the Biological Treatment of Textile Finishing
Wastes"
Chem. Eng. Progr. Symp. Ser. 67, 107, 451-457, 1971.
(Same subject as ref. Ill)
(115) Rodman, C.A. and E. L. Shunney
"Novel Approach Removes Color from Textile Dyeing Wastes"
Water and Waste Eng. (8) No. 9, #18-23, 1971.
(Same subject as ref. Ill)
(118) "Eio-regenerated Activated carbon Treatment of Textile Dye Wastewater"
Water Pollution Control Research Series 1209 OD WW 01/71.
(Same subject as ref. Ill)
(122) Powell, S.D.
"Biodegradation of Authraquinone Disperse Dyes"
Thesis, Georgia Inst. Tech., 9, 238, 1971,
Three authraquinone disperse dyes. Disperse violet 1 (C.I. 61100),
Disperse Blue 3 (C.I. 61505) and Disperse Blue 7 (C.I. 62500),
were partially metabolized by bacteria normally present in domestic
199
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activated sludge. Disperse Red 15 (C.I. 6071C), was left unchanged
by the sludge. The nature of the metabolites produced showed that
the dyes had not actually been degraded, but merely converted to
derivatives of the original dyes.
(123) Hood, W.S.
"Color Evaluation in Effluents from Textile Dyeing and Finishing
Processes"
Initial concentration and rates of degradation of dyes and chemicals
in textile effluents were studied. Field studies were made to
observe conditions .and to collect samples of water from streams in
the Coosa River Basin. The samples were analyzed for content of
specific dye auxiliaries and color. Color degradation was achieved
under simulated stream conditions, both in textile effluents and in
river samples.
(124) Soria, J.R.R.
"Eiodegradability of Some Dye Carriers"
Thesis, Georgia Inst. Tech., 9, 238, 1971.
Carriers covered in this study were resistant to degradation in
conventional activated sludge waste disposal plants. Where bacteria
were acclimated to the chemicals and treatment times were extended,
degradation did occur.
(125) Arnold, L.G.
"Forecasting Quantity of Dyestuffs and Auxiliary Chemicals Dis-
charged into Georgia Streams by the Textile Industry"
Thesis, Georgia Inst. Tech., 9, 238, 1971.
The quantity and concentration of the major textile wet-processing
chemicals in effluents are reported.
(126) Pratt, H.D., Jr.
"A Study of the Degradation of Some Azo Disperse Dyes in Waste
Disposal Systems"
Thesis, Georgia Inst. Tech., 9, 238, 1971.
Two azo disperse dyes. Disperse Orange 5 (C.I. 11100) and Disperse
Red 5 (C.I. 11215), were degraded by the bacteria in conventional
waste treatment facilities into aromatic amines. Biological de-
gradation produced identical metabolites as those formed by chemi-
cal reduction.
(127) Anderson, J.H.
"Eiodegradation of Vinyl Sulfone Reactive Dyes"
Thesis, Georgia Inst. Tech., 9 238, 1971.
Biodegradation of three vinyl sulfone reactive dyes, Reactive
200
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Blue 19, Reactive Violet 5, and Reactive Black 5, were investigated
under laboratory conditions simulating those employed in conventional
activated sludge plants. The study failed to show any evidence of
degradation. Reactive Blue 19, and Reactive Violet 5 showed evidence
of degradation under anaerobic conditions.
(141) "The Centrifugal Recovery of Wool Grease"
Wool Science Review f37, p. 23-36, 1969.
This very detailed article discussed the composition of wool scour
liquor, general principles of recovery, detailed operating charac-
teristics of centrifuges, and the economics of wool grease recovery.
(143) Harker, R.P., and B.M. Rock
"Water conservation and Effluent Disposal in the Wool Textile Industry"
J. Soc. Dyers and Colourists (87), No. 12, 481-3, 1971.
Discusses the wool textile industry in the U.K. Gives water con-
sumption for various unit processes in terms of gal/lb product.
This article also gives typical wool processing effluents and a
description of the Traflo-W process which entails chemical coagu-
lation followed by vacuum filtration. BOD is reduced by 80S.
(149) Rea, J.E.
"Treatment of Carpet Wastes for Disposal"
Proc. Industrial Waste and Pollution Conference and Advanced
Water Conference, 22nd and 3rd. Oklahoma State University,
Stillwater, Oklahoma, March 24-30, 1971.
This paper identifies design criteria and operating data for the
waste treatment facilities at Sequoyah Mills in Anadarko, Okla.
The waste treatment facilities consist of an aerated lagoon and
stabilization pond. Pilot work is included which shows the re-
lationship of BOD removal to aeration time.
(150) Paulson, P.
"Water Purification - An Alternative to Solvent Dyeing"
International Dyer & Textile Printer - June 4, 1971.
A brief description of a new waste treatment process employing
sedimentation -followed by ion exchange. Pilot plant work on
dyeing liquor showed COD removals greater than 90$.
(161) Kulkarni, H.R., S.U. Khan, and Deshpande
"Characterization of Textile Wastes and Recovery of Caustic Soda
from Kier Wastes"
Environmental Health (13) No. 2, 120-127, 1971.
A case study of "A Typical Cotton Textile Industry" is presented
in the paper with reference to economical method, of treatment of
201
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the waste waters and recovery of caustic soda during the process
of treatment. Ninety-eight percent caustic recovery has been
accomplished using dialysis.
(162) "Biodegradation of "Elvanol" - A Report from Du Pont"
The report concludes that domestic and textile mill activated
sludge microorganisms can acclimate to "Elvanol" T-25 under con-
ditions attainable in conventional waste treatment systems and
that removals of over 9058 can be achieved if the organisms are
properly acclimated.
(16U) Ryder, L.W.
"The Design and Construction of the Treatment Plant for Wool
Scouring and Dyeing Wastes at Manufacturing Plant, Glasgow, Va. "
J. Boston Soc. Civil Engrs., 37, 183-203, April 195C.
This article gives a very detailed description and design basis
for the waste treatment system consisting of equalization, acid-
flocculation, and neutralization. The plant achieves a BOD re-
moval of 60%, SS removal of 96X and a grease removal of 97%.
(168) Rodman, C.A., and E.L. Shunney
"Clean Clear Effluent"
Tex. Manufacturer (99) No. US, 53-56, 1972,
A description of the Fram Corporation bio-regenerated carbon
adsorption process is given along with laboratory and pilot plant
operating data. The pilot plant treated waste water from the
carpet yarn fibre dyeing plant of C.H. Masland & Sons, Wakefield,
Rhode Island. A COD reduction of 81X and a color reduction of
99.U% is reported.
(175) Wilroy, R.D.
"Industrial Wastes from Scouring Rug Wools and the Removal of
Dieldrin"
Proc. 18th Irid. Waste Conf., Purdue Univ., April 30, May 1-2, 1963.
The article describes design considerations and operating exper-
ience of a waste treatment system consisting of fine screens,
sedimentation basin, and an anaerobic lagoon. A BOD reduction
of between 80 and 90* and a Dieldrin reduction of 99X is claimed
for the system.
(181) Stewart, R.G.
"Pollution and the Wool Industry"
Wool Research Organization of New Zealand, Report No, 1C, 1S71.
This article is a rather general outline of the sources of wool
processing wastes and the present waste treatment technology
202
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available.
(190) Rebhun, M. , A. Weinberg, and N. Narkis
"Treatment of Wastewater from Cotton Dyeing and Finishing Works
for Reuse"
Eng. Bull. Purdue Univ., Eng. Ext. 137 (pt. 2} , 197C.
This article describes the results of pilot plant work on the
waste from a cotton dyeing and finishing mill in Israel. Alum
flocculation followed by filtration was shown to produce a 95%
color reduction and a 67X COD reduction. Activated carbon was
shown to be a poor sorbent, and greater success was achieved
using a weak base ion exchange resins.
(202) Alspaugh, T.A.
"Treating Dye Wastewaters"
45th Annual Conference of the Water Pollution Control Federation
Atlanta, Georgia, Oct. 8-13, 1972.
Alspaugh gives a very thorough evaluation of presently employed
and promising future waste treatment unit operations. Experienced
removal efficiencies and general treatment costs are also given.
A summary of current waste treatment research is given.
(213) Corning, V.
"Pollution Control in Jantzen Dyehouse"
Knitting Times (39) No. 35, 44-45^ 1970.
Brief description of Portland, Oregon plant, little detail.
(214) "Textile Water Pollution Cleanup Picks Up Speed"
Textile World, 54-66, November 1967.
Fairly general arcicle but does give some operating data and waste
treatment descriptions for several plants: '
1. J.P. Stevens & Co., Wallace, N.C. plant
2. UPD's Bluefield, Va., plant
3. Burlington's Cooleemee, N.C.
4. Lyman Printing and Finishing Co., Lyman, N.C.
5. J. P. Stevens & Co., Utica-Mohawk plant
(215) Sahlie, R.S., and C.E. Steinmetz
"Pilot Wastewater study Gives Encouraging Indications"
Modern Textiles, (50) No. 11, 20-28, 1969.
203
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Description of pilot plant work at Fiber Industries, Shelby, N.C,
plant. Article is not very detailed.
(216) "Trade Effluent Control in the Carpet Industry"
Textile Institute and Industry, (3) No. 9, 237-40, 1965.
General discussion, gives values for typical effluents.
204
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Conference, 22nd and 3rd., Oklahoma State University, Stillwater,
Okla., March 24-30, 1971.
150. Paulson, P., "Water Purification - An Alternative to Solvent Dyeing,"
International Dyer & Textile Printer, June 4, 1971.
151. Rizzo, J.L., "Granular Carbon for Wastewater Treatment," Water &
Sewage Works, (118) No. 8, 238-40, 1971.
152. "Textile Mills Perfect Remedy for Dirtiest Problem: Pollution,"
America's Textile Reporter, (84) No. 15, 18-19, 24-5, 30, 1970.
153. "Achieving Pollution Control in Textiles: A Report," America's Textile
Reporter, (84) No. 22, 20-23, 26, 27, 1970.
154. Work, R.W., "Research at the School of Textiles," North Carolina State
University, Raleigh, North Carolina, 1971.
155. Kollar, I., "Recovery of Zinc Ions from Waste Solutions in the
Processing of Viscose on Ion Exchanger," Czech Patent, (136) No. 147,
(Cl. D olc), April 15, 1970.
156. Khare, G.K., and C.A. Sastry, "Studies on Characterization and
Pollutional Effects of Viscose Rayon Wastes," Environmental Health,
Vol. 12, 99-109, 1970.
157. Garrison, A.W., "The Effect of High Pressure Radiolysis on Textile
Wastes, Including Dyes and Dieldrin," Proc. 5th International Conf.
Water Pollution Research, 1970.
158. Sinev, O.P., "Decomposition of Cellulose Xanthate and Precipitation
of Hydrocellulose During Purification of Waste Waters from Viscose
Manufacture, Fibre Chem., No. 2, 180-3, March - April, 1969.
215
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159. Sinev, O.P., "Removal of Carbon Disulphide and Sulphur Compounds
from Viscose Fibre Plant Effluent by Aeration, " Fibre Chem., No. 4,
436-8, July - August, 1969.
160. Marinich, V., et al., "Removal of Lubricants from Effluents of
Caprolectan Production," Fibre Chem., No. 4, 459-61, July - Aug. 1969.
161. Kulkarni, H.R., S.U. Khan, and W.M. Deshpande, "Characterization of
Textile Wastes and Recovery of Caustic Soda from Kier Wastes," En-
vironmental Health, (13) No. 2, 120^27, 1971.
162. "Eiodegradation of "Elvanol" Polyvinyl Alcohol," Du Pont Company,
Plastics Department, Wilmington, Delaware.
163. Brandon, C.A., "Dynamic-Membrane Hyperfiltration— Key to Reuse of
Textile Dye Waste?" ASME Publication, 71-Tex-4.
164. Ryder, L.W., "The Design and Construction of the Treatment Plant for
Wool Scouring and Dyeing Wastes at Manufacturing Plant, Glasgow,
Virginia," J. Boston Soc. Civil Engrs., 37, 183-203, April 1950.
165. Bogren, G.G., "A Plant for the Degreasing of Wool Scouring Wastes,"
J. Boston Soc. Civil Engrs, (13) No. 1, 18-23, 1926.
166. Masselli, J.W., and M.J. Buford, "Pollution Sources in Wool Scouring
and Finishing Mills and their Reduction Through Process and Process
Chemical Changes," Prepared for New England Interstate Water Pollution
Control Commission.
167. Laude, L., "Economy and Recycling of Water in the Bleaching and
Dyeing Industries," Centre Textile Controle Sci. Bulletin, No. 78,
481-99, June 1971.
168. Rodman, C.A., and E.L. Shunney, "Clean Clear Effluent," Textile
Manufacturer, (99) No. 49, 53-6, A.
169. Barker, R.P., "Effluents from the Wool Textile Industry - Problems
Associated with Treatment and Reuse," Chem. Eng. CE 8-13, Jan./Feb.
1970. (London)
170. Little, A.H., "The Treatment and Control of Bleaching and Dyeing
Wastes," Water Pollution Control, London, 68, 178-89, 1969.
171. Fathmann, D.H., "Solving the Effluent Problem in Textile Mills. I,"
Tex. (Neth.), (29) No. 12, 918-20, 1970.
172. Fathmann, D.H., "Solving the Effluent Problem in Textile Mills. II,"
Tex. (Neth.), (30) No. 1, 37-40, 1971.
216
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173. Laurie, D.T., and C.A. Willis, "Treatment Studies of Combined Textile
and Domestic Wastes."
174. Buswell, A.M., and H.F. Mueller, "Treatment of Wool Wastes," Proc.
llth Ind. Waste Conference, Purdue University, May 15-17, 1956.
175. Wilroy, R.D., "Industrial Wastes from Scouring Rug Wools and the
Removal of Dieldrin," Proc. 18th Ind. Waste Conf., Purdue University,
April 30, May 1-2, 1963.
176. Snyder, D.W., "bow Surfpac Pilot Study on Textile Waste," Proc. 18th
Ind. Waste Conference, Purdue University, April 30, May 1-2, 1963.
177. Stack, V.T., "Biological Treatment of Textile Wastes," Proc. 16th
Ind. Waste Conference, Purdue University, May 2-4, 1961.
178. Williams, S.W., and G.A. Hutto, "Treatment of Textile Mill Wastes
in Aerated Lagoons," Proc. 16th Ind. Waste Conf., Purdue University,
May 2-U, 1961.
179. Gramley, D.L., and M.S. Heath, "A Study of Water Pollution Control
in the Textile Industry of North Carolina," Water Resources Research
Institute of University of North Carolina.
180. Perera, N.A.P., "Textile Effluents and their Safe Disposal," Silk
and Rayon Industries of India, 12, 555-7U, November 1969.
181. Stewart, E.G., "Pollution and the Wool Industry," Wool Research
Organization of N.Z., Report No. 10, 1971.
182. Ganapat, S.V., "Some Observations on In-Plant Process Control for
Abatement of Pollution Load of Textile Wastes," Environmental Health,
(8) No. 3, 169-173, 1966.
183. Veldsman, D.P., "Pollution Resulting from Textile Wastes," Wool
Grower, (23) No. 5, 27, 29, 1970.
184. Judkins, J.F., R.H. Dinius, et al., "Gamma Radiation of Textile
Wastewater to Reduce Pollution," Water Resources Research Inst.,
Auborn, University, Alabama.
185. Howard, M., "Textiles: Special Problems?" Water and Wastes Engineering
March, 1973.
186. Poon, CiP.C., and E.L. Shunney, "Have a Space Problem," Water and
Wastes Engineering, March 1973.
187. "Pollutants are all burned Up," Water and Wastes Engineering,
March 1973.
217
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188. "Clemson has Wastewater Breakthrough," Southern Textile News, 12,
October 18, 1971.
189. "Waste Treatment System at Foremost Recycles Hundred Percent of Water,"
Mill Whistle, (29) No. 6, 2<*3, 6, September 21, 197C.
19C. Rebhun, M., A. Weinberg, and N. Narkis, "Treatment of Wastewater from
Cotton Dyeing and Finishing Works for Reuse."
191. Petru, I.A., "Combined Treatment of Wool Scouring Wastes," J. Inst.
Sew. Purif., Paper No. 3, 497-9, 1964.
192. Kaukare, V.S., "Water Conservation and its Reuse from Treated
Effluents," Textile Dyer and Printer (Ind.) (3) No. 1, 171-5, 1969.
193. "Treatment System Allows 100 Percent Recycling of Wastewater,"
Industrial Waste, (19) No. 2, IW/18-19, March/April, 1973.
194. Ingols, R.S., R. Roberts Jr., and E. Garper, and P. Vira, "A Study
Of Sludge Digestion with Sodium Chloride and Sulfate," PB196732,
Final Report Project No. B 338, under Res. Grant RG 17070, Fed. Water
Quality Admin., Dept. Interior, by Ga. Inst. Tech. Eng. Expt. Sta.,
Atlanta, Ga., September 1970.
195. Rayburn, J.A., "Examine Those Effluents," American Dyestuff Reporter,
(61) No. 9, 103-4, 1972.
196. Case, F.N ,. E.E. Ketchen, and T.A. Alspaugh, "Gamma-Induced Low ,
Temperature Oxidation of Textile Effluents," JAATCC, (5) No. 9, 1973.
197. Natha, Roop, "Mothproofing Without Pollution," JAATCC, (5) No. 3, 1973. «
198. Stovall, J., "The 1972 Water Pollution Control Act Amendments Ana-
lyzed," Modern Textiles, (54) No. 2, 14-16, 19, 23, 1973.
199. Little, A.H., "Measures Taken Against Water Pollution in the Textile
Industry of Great Britain," Pure and Applied Chemistry, 29, 1-3,
355-64, 1972.
200. Eaddy, J.M., "Activated Sludge Treatment of Textile Wastes to Meet
High Stream Classifications - What Standards and How to Meet Them,"
AATCC National Technical Conference, September 28-30, 1972.
201. Williams, H.E., "Treatment and Reuse of Screen Printing Dye Waste
waters," Paper presented at the 45th Annual Conference of the Water
Pollution Control Federation, October 8-13, 1972.
202. Alspaugh, T.A., "Treating Dye Wastewaters," Paper presented at the 45th
Annual Conference of the Water Pollution Control Federation, October
8-13, 1972.
218
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203. Rayburn, J.A., "Overall Problems of Tertiary Treatment of Textile
Waste for the Removal of Color, COD, TOC, Suspended Solids,
Dissolved Solids, etc.," Paper presented at AATCC National Technical
Conference, Philadelphia, Pa., September 28-3C, 1972.
204. "Color, Heavy Metal Removed by Adsorption," Chemical Processing, (35)
No. 9, 13, 1972.
205. "Water Usage in the Wet Processing of Wool Textiles," Wira Report 79.
206. Cosgrove, W.J., "Water Pollution and the Textile Industry," Canadian
Textile J., 63-6, January 1970.
207. Eguchi, Y., and Y. Uda, "Wastewater Treatment by Granular Activated
Carbon," J. Textile Machinery Soc. Japan, (24) No. 8, 555-61, 1971.
208. Jones, T.R., "Textile Industry Wastes: Effluent Treatment: Waste
Reclamation: Man-made Fibers," Effluent & Water Treatment Journal,
London, (12) No. 7, 352-355, July 1972.
209. Simon-Hartley, "Treatment of Dyeing and Finishing Effluents from a
Textile Works," Intern. Dyer, (143) No. 51, 53-4, January 2, 1970.
21C. Hutton, D.G., "Improved biological wastewater treatment," Du Pont
Innovation, (3) No. 1, 6-8, 1972. (Eng.)
211. Rhame, G.A., "Review of South Carolina Practices in Textile Finishing
wastes," Industrial Waste, 18 IW/49-53, September-October 1972.
212. "Textile Industry Wastes: Effluent Treatment: Water Reclamation:
Great Britain," Textile Res. Conference, Final Report, 73 pages.
213. corning, V., "Pollution Control in Jantzen Dyehouse," Knitting Times
(39) No. 35, 44^45, 1970.
214. "Textile Water Pollution Cleanup Picks Up Speed," Textile World,
54-66, November 1967.
215. Sahlie, R.S., and C.E. Steinmetz, "Pilot Wastewater Study Gives
Encouraging Indications," Modern Textiles, (50) No. 11, 20-28, 1969.
216. "Trade Effluent Control in the Carpet Industry," Textile Institute
and Industry, (3) No. 9, 237-40, 1965.
219
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SECTION XIV
GLOSSARY
acetate - A manufactured fiber made from cellulose acetate.
acid dye - A type of dye commonly used to color wool and nylon but
may be used on other fibers.
Acrilan - Trademark of Monsanto for acrylic fiber.
acrylic - A manufactured fiber in which the fiber-forming substance
is any long chain synthetic polymer composed of at least 85* by
weight of acrylonitrile units. Made in both filament and staple
form. (See Acrilan, Orion, Creslan.)
Arnel - Trademark (Celanese Corp.) for cellulose triacetate fiber.
Avicron - Trademark (FMC Corp.) for rayon filament yarn.
Avril - Trademark (FMC Corp.) for staple and filament rayon.
beck - A chamber in which goods may be scoured and dyed. May be
operated at atmospheric pressure or at elevated temperature and
pressure.
biochemical oxygen demand (BOD) - A method of measuring rate of
oxygen usage due to biological oxidation. A BOD5 of 1000 mg/liter
means that a sample (1 liter) used 1000 mg of oxygen in 5 days.
biphenyl (or diphenyl) - A carrier used in dyeing polyester.
bleaching - Removal of colored components from a textile, common
bleaches are hydrogen peroxide, sodium hypochlorite, and sodium
chlorite.
blend - the combination of two or more types of fibers and/or colors
in one yarn.
bottom chrome - Term used in application of certain dyes to wool.
Involves use of chromium compounds.
butyl benzoate - A carrier used in dyeing polyester.
carded - Yarn in which fibers are separated and aligned in a thin
web, then condensed into a continuous, untwisted strand called a
"sliver."
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carrier - An organic material used in dyeing polyester. (See
biphenyl, orthophenyl phenol, trichlorobenzene, butyl benzoate.)
cationic dye - The colored component of this type of dye bears a
positive charge.
caustic soda - A strong alkali used, for example, in mercerizing.
cellulose - Major component of cotton and rayon. Also used as the
base for acetate fiber.
chemical oxygen deman (COD) - The amount of oxygen required to
oxidize materials in a sample by means of a dichromate solution.
combed cotton - Cotton yarn that is cleaned after carding by wire
brushes (combs) and roller cards to remove all short fibers and
impurities.
Commission finishing - The term "commission finishing" shall mean
the finishing of textile materials, 50 percent of more of which are
owned by others, in mills that are 51 percent or more independent
(i.e. only a minority ownership by company (ies) with greige or
integrated operations); the mills must process 20 percent or more of
their commissioned production through batch, non-continuous
processing operations, with 50 percent or more of their commissioned
orders processed in 5,000-yard or smaller lots.
crease^resistant - Fabrics that have been treated to make them
resistant to wrinkling. One of the most common methods is to
incorporate a resin.
Creslan - Trademark owned by American Cyanamid Co. for acrylic
fibers.
cross-dyed - Multicolored effects produced in one dye bath from
fabrics containing fibers with different affinities to the same dye.
Dacron - Trademark owned by Du Pont for polyester filaments and
staple fibers.
denier - Unit of weight indicating size of a fiber filament based on
weight in grams of a standard strand of 9000 meters.
desize - Removal of size. Several methods may be used. (See
enzyme.)
developed dye - An azo dye whose color is developed by reaction on
cotton.
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dichromate - A chemical used widely in applying some dyes. Also
used in boiler water. A toxic material.
dieldrin ~ Chemical applied to wool to eliminate damage due to
moths. Toxic.
diphenyl - (See biphenyl).
direct dyes - Class of dyestuffs that colors cellulosic fibers in
full shades.
disperse dye - A type of dye used to color several synthetic fibers.
Applied as a fine dispersion using a carrier. On cloth, padded dye
may be baked on or "thermofixed. '•
dissolved solids - Total solids - suspended solids in a sample of
waste water.
dope-dyed - Trade slang for "solution dyed" or "spun dyed" meaning
that color is put into the chemical liquid from which synthetic
fibers are drawn. Filaments emerge colored.
double knit - Knitted fabric made on a special knitting machine that
combines a double set of needles to produce a fabric.
Durable Press - Goods that require no ironing during the normal use-
life of a garment. The term applies to apparel and other textile
products such as sheets, draperies, etc. As a rule, DP is achieved
in two ways: 1. Pre-curing fabrics with a special resin finish
then pressing made-up garment. 2. Post-curing fabric with a resin
finish then cooking made-up garments in an oven. As a rule,
polyester-cotton blends are used, but there are 100% cottons, and
, other blends also.
enzyme - An agent used to remove starch size.
felt - A mat of fiber of wool often mixed with cotton or rayon.
flock - Short fibrous particles of fibers or short hairs applied by
various processes to the surface of a fabric.
fly - Waste fibers or particles which fly out into the air during
carding, drawing, spinning, or other fiber processing.
Fortrel - Trademark owned by Fiber Industries, Inc., for polyester
fiber.
greige - Fabrics in unbleached, undyed state before finishing. In
U.S., "gray goods" or "grey goods."
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Herculon - Trademark owned by Hercules, Inc., for polypropylene
fibers.
jig—dyed - Dyed in open width on a machine called a "jig." Cloth
moves from one roll to another through the dye liquor until the
desired shade is obtained.
jute - Coarse, brown fiber from the stalk of a bast plant grown in
India. Used mainly for burlap, cordage, and as a backing for rugs
and carpets.
kier - A piece of equipment in which cotton is boiled with dilute
caustic soda to remove impurities. Also used as a verb to describe
the process.
knitting - Process of making fabric by interlocking series of loops
of one or more yarns. Types are: jersey (circular knits), tricots
(warp knits), double knits.
Kodel - Trademark owned by Eastman Chemical Products Inc. for
polyester yarn and fiber.
Lycra - Trademark (Du Pont) for polyurethane multifilament elastic
yarn. The fused multifilaments in a bundle form a monofilament yarn
that stretches and snaps back.
mercerizing - Finish used on cotton yarns and fabrics to increase
luster, improve stretch and dyeability. Treatment consists of im-
pregnating fabrics with cold concentrated sodium hydroxide solution.
Matin - Trademark owned by Geigy Co., Inc. for a moth-repellent
finish for woolens.
modacrylic - Generic name established by the Federal Trade
Commission for a "manufactured fiber in which the fiber-forming
substance is any long-chain synthetic polymer composed of less than
85* but at least 35% by weight of acrylonitrile units."
mordant - A metallic salt used for fixing dyes on fibers.
naphthol dye - A azo dye whose color is formed by coupling with a
naphthol. Used chiefly on cotton.
non-woven - A material made of fibers in a web or mat generally held
together by a bonding agent.
nylon - Generic name for "a manufactured fiber in which the fiber-
forming substance is any long-chain synthetic polyamide having
recurring amide groups as an integral part of the polymer chain."
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Orion - Trademark (Du Pont) for acrylic fiber.
ortho phenyl phenol - A carrier used in dyeing polyester.
package dye - A method for dyeing many cones of yarn at once by
pumping a dye solution through the yarn.
permanent finish - Fabric treatments of various kinds to improve
glaze, hand, or performance of fabrics. These finishes are durable
to laundering.
pH scale - A method used to describe acidity or alkalinity. pH 7 is
neutral; above 7 - alkaline; below 7 - acid. The scale extends from
0 to 14 and a change of 1 unit represents a tenfold change in
acidity or alkalinity.
pigment prints - Made with insoluble pigment mixed with a binder and
thickener to form the printing paste.
pile fabric - Fabric with cut or uncut loops which stand up densely
on the surface.
polyamide - (See nylon.)
polyester - A manufactured fiber in which the fiber-forming
substance is any long-chain synthetic polymer composed of at least
85% by weight of an ester of dihydric alcohol and terephthalic acid.
(See Dacron, Fortrel, Kodel.)
polypropylene - Basic fiber-*forming substance for an olefin fiber.
Post-cured - Technique for imparting durable press that requires
baking apparel in ovens to cure fabrics that have been impregnated
with special resins. Most common technique used with polyester and
cotton blends. (See durable press.)
precured fabric - Technique for imparting durable press by
impregnating fabrics with special resins then curing same. Does not
require oven after-treatment of apparel. (See durable press.)
printing - Process of producing designs of one or more colors on a
fabric. There are several methods, such as roller, block, screen,
etc., and several color techniques, such as direct, discharge, and
resist.
print paste - A mixture containing a dye or pigment used in
printing. Generally contain gums (thickener) and a solvent. (See
also pigment prints.)
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raschel - Warp-knit, similar to tricot, but coarser. Made in a wide
variety of patterns.
rayon - A generic name for man-made fibers, monofilaments, and con-
tinuous filaments, made from regenerated cellulose. Fibers produced
by both viscose and cuprammonium process are classified as rayon.
reactive dyes - Dyes that react chemically with the fiber.
resin - A chemical finish used to impart a property desired in a
fabric, such as water repellency or hand, etc. (See durable press.)
resist dye - Method of treating yarn or cloth so that in dyeing the
treated parts do not absorb the dyestuff.
roller prints - Machine made, using engraved copper rollers, one for
each color in the pattern.
scouring - Removal of foreign components from textiles. Normal
scouring materials are alkalies (e.g., soda ash) or trisodium phos-
phate, frequently used in the presence of a surfactant. Textile
materials are sometimes scoured by use of a solvent.
screen prints - A screen of fine silk, nylon, polyester, or metal
mesh is employed. Certain areas of the screen are treated to take
dye, others to resist dye. A paste color is forced through the
screen onto the fabric by a "squeegee" to form the pattern.
sequestrant - A chemical used to bind foreign metal ions.
Frequently used in dyeing. A common sequestrant is EDTA.
size - A material applied to warp yarns to minimize abrasion during
weaving. Common sizes are starch, polyvinyl alcohol (PVOH), and
carbonxymethyl cellulose. Sizes are applied continuously in a
slasher.
softener - A chemical used to apply a soft, pleasant hand. Fat
derivatives and polyethylene are common softeners.
solution-dyed - Synthetic fibers sometimes are dyed by adding color
to the chemical polymer before fibers are formed. Also called dope
dyed.
standard raw waste load (SRWL) - A description of the properties of
waste water before treatment.
starch - Organic polymer material used as a size; highly
biodegradable.
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sulfur dye - A class of dyes which dissolve in aqueous sodium
sulfide forming products with a marked affinity for cotton; the dyes
are regenerated by air oxidation.
suspended solids - Amount of solids separated by filtration of a
sample of waste water.
textured - Bulked yarns that have greater volume and surface
interest than conventional yarn of same fiber.
top chrome - Term used in application of certain dyes to wool.
Involves use of chromium compounds.
top-dyed - Wool which is dyed in the form of a loose rope of
parallel fibers prior to spinning fibers into yarn.
total organic content (TOC) - The total organic materials present in
a sample of waste water.
total oxygen demand (TOD) - The amount of oxygen necessary to
completely oxidize materials present in a sample of waste water.
total solids - Amount of residue obtained on evaporation of a sample
of waste water.
triacetate - Differs from regular cellulose acetate, which is a di-
acetate. The description implies the extent of acetylation and
degree of solubility in acetone.
tricot - Warp-knitted fabric. Tricots are flat knitted with fine
ribs on the face (lengthwise) and ribs on the back (widthwise).
tufted fabric - Fabric decorated with tufts of multiple ply yarns.
Usually hooked by needle into fabric structure. Used widely for
carpets.
vat dye - A type of dye applied from a liquor containing alkali and
a powerful reducing agent, generally hydrosulfite. The dye is
subsequently oxidized to the colored form. Widely used on
cellulosic fibers.
warp - Set of lenthwise yarns in a loom through which the crosswise
filling yarns (weft) are interlaced. Sometimes called "ends."
weaving - The process of manufacturing fabric by interlacing a
series of warp yarns with filling yarns at right angles.
yarn - An assemblage of fibers or filaments, either manufactured or
natural, twisted or laid together so as to form a continuous strand
227
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which can be used in weaving, knitting, or otherwise made into a
textile material.
yarn-dyed - Fabrics in which the yarn is dyed before weaving or
knitting.
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A-l
APPENDIX A
PROCEDURE FOR DETERMINING ADKt COLOR VALUE
I. Principle
The color of a sample is considered to be the color of the light transmitted by
the solution after removing the suspended material, Including the pseudo-colloidal
particles. It is recognized that the color characteristics of some samples are
affected by the light reflection from the suspended material present. However,
until a suitable method is available for making solution reflectance determinations,
the color measurements will be limited to the characteristics of light transmitted
by clarified samples. Suspended materials are removed by filtration through a
standard filter aid medium.
This method is based on the premise that the Adams Nickerson Chromatic Value
formula for calculating single number color difference values from C.I.E. tri-
stimulus values adequately transforms C.I.E. color space into a visually uniform
color space so that if two colors, A and B, are visually judged to differ from
colorless to the same degree, the vector in the transformed color space from
colorless to color A will be the same length as the vector from colorless to
color B, the length of these vectors being the single number uniform color
difference.
Thus a blue solution which would be visually judged to differ from colorless to
the same degree that the APHA 100 platinum-cobalt color standard (yellow) differ*
from colorless would have a vector in Adams Nickerson Chromatic Value COAOI. space
from colorless to the point for the blue solution which is equal in length to the
vector from colorless to the point for the APHA 100 platinum-cobalt standard, and
thus the two colored solutions would have similar single number color difference
values. The scaling coefficient has been defined so that the values so calculated
are of the same magnitude as the values assigned to the APHA platinum-cobalt
standards, that is the ADMI Value for the blue solution would be 100.
II. Pretreatment of Samples
1. Apparatus (see Footnote A)
A filtration system, consisting of the following (see Figure 30, Section 206A (2)
of Standard Methods):
a. Filtration flasks, 250-ml, with side tubes.
b. Walter crucible holder.
c. Micrometallic filter crucible, average pore size 40 microns.
d. Calcined filter aid.*
e. Vacuum system.
*Celite No 505 (Johns-Manville Corporation) or equivalent.
The procedure given Is taken from 13th Edition of Standard Methods. However,
it is considered to be Inconvenient and requires attention to produce a clear
filtrate. A more convenient procedure is to use the precoat technique on a
circle of glass-fiber filter paper (5.5 cm Reeve Angel Glass Fiber Filter Papei
Grade 934AH) supported on a Buchner funnel.
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A-2
2. Procedure
a. Preparation of sample: Bring two 100 ml samples to room temperature.
Use one sample at the original pH value (record pH value), adjust the pH value of
the other to 7.6 by using cone H2S^A or NaOH as required. A standard pH is
necessary because of the variation of color with pH. Remove excessive quantities
of suspended materials by centrifuging. Treat each sample separately, as follows:
Thoroughly mix 0.1 g filter aid in a 10-ml portion of centrifuged sample and filter
the slurry to form a precoat in the filter crucible. Direct the filtrate to the
waste flask as indicated in Figure 30 (Section 206A (2) of Standard Methods). Mix
80 mg filter aid in a 80-ml portion of the centrifuged sample. While the vacuum
is still in effect, filter through the precoat and pass the filtrate to the waste
flask until clear; then direct the clear filtrate flow to the clean flask by means
of the three-way stopcock and collect 70 ml for the transmittance determination.
III. Spectrophotometry
1. Apparatus
a. General
Procedures are given for a wide variety of color measuring instruments. As
already pointed out, it is important, however, that the instrument be calibrated
as described in Section V and the calibration data for one instrument not be
applied to another instrument, particularly a different type instrument or an
instrument employing a different cell path length.
b. Cells
Clean, matched cells with a cell path of 5.0 cm are recommended where color values
are less than 250. Cell paths of 1.0 cm should be used where samples have higher
color values; however, calibration must be carried out using appropriate higher
APHA platinum-cobalt color standards.*
c. Reference Liquid
In all cases the reference is a cell of the same nominal path length filled with
distilled water. For all double beam instruments a "100% line" is measured (both
cells filled with distilled water) and these measurements used to generate the
X , Y and Z (tristimulus values for "colorless") used in subsequent calculations.
For single-beam instruments, the reference cell is used to set "100% T" prior to
each measurement of the colored solution. In this instance fixed values for
X , Y , and Z given in Section III are used.
c c c
*When a spectrophotometer is used for the color measurement, alternatively samples
may be diluted prior to measurement in a 5.0 cm cell and the calculated value
multiplied by the dilution factor. This alternative is not recommended when the
instrument is a filter colorimeter. In this case a shorter cell path and the
appropriate calibration should be employed.
230
-------
A-3
2. Measurement Procedure
a. Double-beam spectrophotometers equipped with a tristimulus integrator
or digital computer giving tristimulus value read-out: Record a "100% line" (both
cells filled with distilled water) from 400 nm to 700 nm with control parameters
set so that the read-out will be the values for X, Y, Z (as percentage) for C.I.E.
Source C. Designate these values as X , Y , Z . Rinse the sample cell twice and
then fill with clarified sample (Section II above) and record the absorption
spectrum of the sample in the same manner. Designate the tristimulus values of
the sample as X , Y , Z .
Q O 9
b. Double-beam ratio-recording spectrophotoraeters - Record a "100% line"
(both cells filled with distilled water) from 400 nm to 700 nm with the instrument
controls set to record percent transmittance. Rinse the sample cell twice and then
fill it with clarified sample (Section II above) and record the spectrum of the
sample in the same manner.
The plotted curves are used to calculate C.I.E. tristimulus values using either
the Weighted Ordinate Method, the Ten Selected Ordinates Method or the Thirty
Selected Ordinates Method. The tristimulus values for the "100% line" are
designated X , Y , Z , the values for the sample X , Y , Z .
C C C S S S
c. Abridged Spectrophotometers (Color-Eye)
(1) Using Four Tristimulus Filters - Follow the manufacturer's
instructions for transmittance measurements and calculation of the C.I.E.
Tristimulus Values. Use a cell filled with distilled water to generate the
tristimulus values for "colorless" and designate these values X , Y , Z . Use
the same cell filled with clarified sample (Section II above) to generate the
sample tristimulus values and designate these X , Y , Z .
S S S
(2) Using Wavelength Isolation Interference Filters - Follow the
manufacturer's instructions for transmittance measurements and calculation of
C.I.E. Tristimulus Values (Source C).
Use a cell filled with distilled water to generate the transmittance data for
"colorless" and from the values calculate the tristimulus values (Source C)
designated X , Y , Z . Use the same cell filled with clarified -sample solution
(Section II above) to generate the "sample" transmittance data and from these
data calculate the tristimulus values (Source C) designated X , Y , Z .
S S S
d. Single Beam Manual Spectrophotometers (Beckman DU-2) - Fill the
reference cell with distilled water and fill the matched sample cell with
clarified sample. At each required wavelength, set the transmittance scale to
100%. With the reference cell in the light beam balance the instrument as
detailed in the manufacturer's instructions, then move the sample cell into the
light beam, bring the instrument to balance by adjusting the transmittance knob,
then read and record the percent transmittance at that wavelength. Replace the
reference cell in the light beam, adjust the wavelength scale to the next required
wavelength and repeat.
231
-------
A-4
The wavelengths at which transraittance measurements must be made depend on which
method of calculating C.I.E. Tristimulus Values is employed, the Weighted
Ordinate Method, the Ten Selected Ordinates Method or the Thirty Selected
Ordinates Method. Convenient work sheets for calculation of the tristimulus
values X , Y , Z are given. In this instance only the tristimulus values for
"colorlets" Ire fixed as follows:
X - 98.06
YC - 100-.00
ZC - 118.14
IV. Conversion of C.I.E. Tristimulus Values to Munsell Values and Calculation of
ADMI Color Value
1. Convert the six C.I.E. tristimulus values X , Y , Z and X , Y , Z to
c c c ss s
the corresponding values for V , V , and V by the use of tables giving the
interdependence of X and V , Y and V , Z and V (the most convenient tables are
in J. Soc. Dyers and Colorists, J56_, No 8, 354 (1970); Tables 6.4(A), 6.4(B), and
6.4(C) of Color Science by Wyszecki and Stiles, Wiley, N. Y., 1967; or Tables A, B
and C in the Appendix of "Color in Business, Science and Industry," 2nd Edition,
by Judd and Wyszecki, Wiley, N. Y. (1963).*
2. Calculate the intermediate value DE from the following equation:*
DE - [(0.23AV )2 + (A(V - V ))2 + (0.4A(V -V))2]1/2
y x y y z
3. Calculate the ADMI value by interpolation on a plot of DE versus ADMI
value or by one of the other alternatives given in Section V-3.
V. Calibration of Color Measuring Instrument
1. Preparation of Standards
a. Dissolve 1.246 g potassium chloroplatinate, KjPtCl, (equivalent to
500 mg metallic platinum) and 1.00 g crystallized cobaltous chloride, CoCl • 6H 0
(equivalent to about 250 mg metallic cobalt) in distilled water with 100 ml cone
HC1 and dilute to 1,000 ml with distilled water. This stock standard has a color
of 500 units.
b. If potassium chloroplatinate is not available, dissolve 500 mg pure
metallic platinum in aqua regia with the aid of heat; remove nitric acid by
repeated evaporation with fresh porticr«= of cone HC1. Dissolve this product,
together with 1.00 g crystallized cobaltous chloride, as directed above.
*A work sheet convenient for carrying out the tabulation and calculations
required is given.
232
-------
A-5
c. Prepare standards having colors of 25, 50, 100, 150, 200 and 250
by diluting 5.0, 10.0, 20.0, 30.0, 40.0, and 50.0 ml stock color standard with
distilled water to 100 ml in volumetric flasks. Protect these standards against
evaporation and contamination.
2. Spectrophotometry of Standards
a. Carry each standard through the spectrophotometry procedure
appropriate for that instrument being used as described in Section III above.
b. Calculate for each color standard values for X , Y , Z . If the
spectrophotometry was all carried out at the same time a single 8100i? line"
recording will suffice to generate values for X , Y , Z .
c c c
3. Calculation of Calibration Factor (F)
a. From the values of X , Y , and Z for each color standard and the
values for X , Y , and Z , calculate for each color standard the intermediate
value DE as described in Section IV above.
A plot of (DE) on the X axis and ADMI value on the Y axis should be prepared.
Then when a sample is carried through the procedure and the intermediate value
DE has been calculated, this plot can be used to determine the ADMI value.
Figure 4 illustrates such a plot for one recording spectrophotometer equipped
with a tristimulus integrator.
b. As an alternative to the use of a calibration graph as described
in a. above, an empirical equation relating DE and ADMI (APHA) value may be
developed. The data from spectrophotometers have been found'to give a good fit
to a hyperbolic equation of the form:
ADMI Value DE
a + (b x DE)
The "least squares" evaluation of the coefficients a and b is described in
"Precision Measurement and Calibration," Vol 1, Statistical Concepts and Procedures,
SP300, National Bureau of Standards, p 234. For one recording spectrophotometer
a was 3.503 x 10 and b was -2.689 x 10~ .
c. Calculate for each color standard the calibration factor (F)
by the following equation:
(APHA) (b)
(F). -
'n (DE)n
where (APHA) - APHA Color Value for Standard n.
n
(DE) - Intermediate value calculated as above for Standard n.
n
b - Cell path used in spectrophotometry, cm.
233
-------
A-6
For undemanding work the values for (F) may be averaged to give a mean value
of F to use in the calculation of ADMI values of samples as shown in Step 8
of the work sheet*,
Then ADMI Value -
Calculation of the C.I.E. tristimulus values is described and illustrated and
a work sheet for calculation of ADMI values from Munsell values is also included.
Alternatively, tristimulus values may be calculated by the 10 or the 30 selected
ordinate methods as described in Section 206A of the 13th Edition of Standard
Methods for the Examination of Water and Waste Treatment .
*This value should be approximately 1.4 x 10 for the meau v,f APHA 50, APHA 100,
and APHA 150 standards as measured on a recording spectrophotometer equipped
with a tristimulus integrator.
234
-------
A-7
CALCULATION OF C.I.E. TRISTIMULUS VALUES
BY THE WEIGHTED ORDINATE METHOD
This method requires trans mi ttance data at equal 10 nm intervals from
400 nm to 700 ntn, a total of 31 data points. Each transmi ttance value is multi-
plied 1'V a weighting factor for X, another weighting factor for Y and a third
weighting factor for Z. There are thus three weighting factors for each of the
31 wavelengths. The products for each of the three C.I.E. primaries are then
summed to give the three C.I.E. Tristimulus Values:
X - < Vl ' f*X-l> + + -
Z - (Vl ' fzA-l> + + - «TX-31 ' f2X-31>
this method requires 85 multiplications and 3 additions, 2 of 31 terms
each, and one of 23 terms, it is not too cumbersome using a desk calculator.
Programmable electronic calculators make it even simpler and access to a
time-sharing digital computer terminal makes it even quicker.
An advantage of this method is that the transmittance dnta are at
unit wavelengths which are easily and quickly set on a wavelength scale or read
on the wavelength grid of a spectrophotoraetric curve.
Included is a work sheet which gives the 93 weighting factors for
C.I.E. 1931 Tristiraulus Values, Source C. A worked example is included.
235
-------
WORK SHEET FOR CALCULATION OF ADMI
VALUES FROM C.I.E. TRISTIMULUS VALUES
Si
to
C.I.E. Tristimulus
Values
V
V
Calibration Factor (F) =
Cell Path Length, cm(b)=
Step (8)
(V -V )
x
(v~vz>
Xc =
Y =
C
Z =
c
X =
s
Ys =
Zs =
Step (1)
Step (2)
Step (3)
Step (4)
Step (5)
Step (6)
Step (7'
AV =
V
0.23AV =
y
i
-------
Work Sheet for Calculation of
C.I.E. Tristimulus Values
Weighted Ordinate Method
A-8
(1) (2)
1
2
1
5 5
Durrouith» ,— •ffaj&ji
Form H5S6 But! • Form GS56 Gn
_ „ „ L
-• J- t; ic P- j c- W oc -i r>
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in
•
- -'"i
"'i
~"\
•-"-'-T
1
:u
32
:; i
3ti
37
j
..!!
.'"1
. Jl
Wavelength
nm.
400
410
420
430
440
450
460
470
480
490
500
510
520
530
540
550
560
570
580
590
600
610
620
.630
640
650
660
670
680
690
700
T
- -
-
-
- -- •
^
Factor
C
C
c
c
c
c
c
c
c
c
c
_.
.
.
•
^
—
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0
0
0
0
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.
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0363
0;052
0
0
0
1 —
8
7
15;2
~278
i ;
3
5
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r
4l2!82
588
-4
!3
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r
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2
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3,693
2
3
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3
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-
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--t -
...
23
7
1
|
( 4 ) ( 5 ) ~ t 6 > *
•5
Factor
0.0
0.0
0.0
O.'O
0.0
0.0
0.0
0.0
0.0
o.'o
0.0
0.0
' 0.0
6.0
T.JO
o.c
fie
o.c
1 1
o.c
o.c
-Ire
-••-f-1--
f,c
9ic
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. 1 .
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DDO{
003"
Di£
326
04
06
10
fe
23
34
4S
64
7:9
4
9<
5(
1"
5
0
3
6
3
9|83
-- L L .
9114
7,9,9
662
5311
4J1
31.
3|4|
(J8|
7
5
9
4
8
050
025
3
qoe
qds
- 1
Sum
• •
i
i
.
)
Y
F
1
1
I
3
*
5
I
j "
j
7
I
7
5
S
3
3
3
5
t
t
2
6
*T x Fact.
• •
-
- , •
;
L
•
• •
'•;
• 1
Z;
Factor ?4T x Fact
0.0(351^ ': 1
O.ok.570
OV2J0638 r
0.1^299
O.lk972 '
0.0^461
0.05274
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
6.0
'676
0.0
0.0
0.0
o.c
o.q
o.c
o.c
o.c
o.c
o.c
z =
2864
0712 j I
0388 i' ;
019S i| i
CTOU6 j
0039
0020 •
0016 1
i|
poio ii
0007 j!
0002 |i
0002 i! '
OOOO '' 0^00
OOOO ; OJOO
oooo b
-------
A-10
WORKED EXAMPLES OF CALCULATION OF C.I.E. TRISTIMULUS VALUES
AND CONVERSION TO ADMI COLOR VALUES
The data used in the example calculating the C.I.E. Tristimulus Values
by the Weighted Ordinate Method were taken from a transmittance curve obtained
on a Gary 14 double beam spectrophotometer using as sample an NBS 2105 glass
filter (2.93 mm). The C.I.E. Source C tristimulus values given by NBS for this
filter are as follows:
X - 51.8 + 0.4
Y - 56.1 + 0.3
Z - 75.4 + 0.7
Also included in this Appendix is a worked example of conversion of the C.I.E.
Tristimulus Values (Selected Ordinate Method) to ADMI Color Value. This
calculation assumes that the data were obtained on a solution measured in a
5 cm cell. Attention is drawn to the necessity of keeping track of the algebraic
sign of the differences calculated.
238
-------
Work Sheet for Calculation of
C.I.E. Tristimulus Values
Weighted Ordinate Method
A-ll
Wave! ength
nm.
400
410
420
430
440
450
460
470
480
490
500
510
520
530
540
550" "
560
570
580
590
600
610
620
630
64C
650
660
670
680
690
700. "
.._
%
T
23.8
40.0
48.2
54.4
60.3
65.8
70.1
71.5
70.9
68.5
66.1
62.9
59.5
57.0
57.0
60 . 5
62.3
58.8
51.4
44.9
44.9
46.4
46.6
45.8
44.8
45.0
43.4
54.3
63. 0"
72.0
79.l"
- -. r!
Factor
0.00108
0.00329
0.01238
0.02997
0.03975
- -
0.03915
0.03362
0.02272
0.01112
0.00363
0~00052
0.00089
0.00576
0.01523
0.02785
0.04282
0.05880
0.07322
0.08417
0.08984
0.08949
0.08325
0.07070
0.05309
0.03693
0.02349
0.01361
0.00708
0.00369
0.00171
0.00156
X = Sum
. . | ...
• i
1
I
X
%T x Fact. Factor
OJD257
' 0.1!316
0.5967
1.6304
2.3'969
_ 4 .
2.5761
2.3567
1.6244
0 . 7884
0 . 2486
d7oT4?
0.0560
0.3472
0.8681
1.5874
Z.5906
3.6632
1 0.00002
! 0.00009
j
j 0.00037
1 0.00122
! 0.00262
i- •-
j 0.00443
j 0.00694
| 0.01058
I 0.01618
i 0.02358
1 0.03401
!' 0.04833
j 0.06462
0.07934
' 0.09149
0 ."09832
0.09841
.
4.3053 0.09147
4.3262
4.0338
4.0181
3.8628
3.2946
2.4315
1.6545
1.0570
0.5907
0.3844
0.2325
.;.
0.1231
0.1234
= 51.96
.......
....
_V
1 L.:..
..li [__.
. '
;
-;
0.07992
0.06627
0.05316
0.04176
0.03153
0.02190
0.01443
0.00886
0.00504
; 0.00259
0.00134
:
0.00062
0.00056
Y = Su- -
. . _ . ,
!
' • •
:,
', j
239
Y
%T x Fact. Factor
0.0005
0.0036
0.0178
0.0664
0.1580
0.2915
0.4865
0.7565
1.1472
1.6152
2.2481
3.0400
3.8449
4.5223
5,2149
5.9484~,
6.1309
5.3784
4.10-79
2.9755
_l
0.00513
0.01570
0.05949
0.14628
0.19938
0.20638
0.19299
0.14972
0.09461
0.05274
0.02864
0.01520
0.00712
0.00388
0.00195
0.00086
• Q.OOOj^
0.00020
0.00016
0.00010
2.38691 0.00007
1.9377 0.00002
1.4693 0.00002
1.0030 0.00000
0.6465 1 ' 0.00000
0.3987; 0.00000
0.2187 0.00000
0.1406
0.0844
0.0446
0.0443
56.33
0.00000
0.00000
0.00000
"" 0.00000
Z = Sum: =
Z
%T x Fact.
0.1221:
0.6280'
2.8674
7.9576
12.0226
13.5798
13.5286
10.7050
6.7078
3.6127
1.8931;
0.9560
0.4236'
0.2212
0.1111
0.0520
0.0243
O.Ollb
0.0082.
0.0045
0.0031
0.0009
O.OOCs
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
75.44 ;
,
i
j
i
1
i
-------
WORK SHEET FOR CALCULATION OF ADMI
VALUES FROM C.I.E. TRISTIMULUS VALUES
-O
o
C.I.E. Tristimulus
Values
(
Xc = 98.00
YC = 100.00
ZG = 118.35
X = 51.96
Y = 56.33
s
Z = 75.44
s
Step (1)
Step (2)
Step (3)
Step (4)
Step (5)
Step (6)
Step (7)
Calibration Factor
9.900
•7.643
9.902
7.841
AV = 2.061
V
0.23AV = 0.474
9.910
8.263
-0.002
-0.198
A(v -V ) = 0.196
• ^ y
-0.008
-0.422
A(Vy-Vz) a 0.414
(0.23AV )2 .
(A(V -V ))2»
x Y
0.4A(Vy-Vz) = 0.166 (0.4A(Vy-Vz))2=
DE sy/Sum = v/ 0.290
(F) = 1.4 x 103
0.539
Sum =
0.225
0.038
0.027
0.290
Cell Path Length, cm(b):
Step (8)
5.0
ADMI Value = F - - = (1.4x10^ x ( 0.539 )
3 ^^^^™"™—^^^^*^^"^"^^™^^^^^^^^^^"^^~"™^^~*
5
= 151
-------
METRIC UNITS
CONVERSION TABLE
MULTIPLY (ENGLISH UNITS) by TO OBTAIN (METRIC UNITS)
ENGLISH UNIT ABBREVIATION CONVERSION ABBREVIATION METRIC UNIT
acre ac
acre - feet ac ft
British Thermal
Unit BTU
British Thermal
Unit/pound BTU/lb
cubic feet/minute cfm
cubic feet/second cfs
cubic feet cu ft
cubic feet cu ft
cubic inches cu in
degree Fahrenheit F°
feet ft
gallon gal
gallon/minute gpm
horsepower hp
inches in
inches of mercury in Hg
pounds lb
million gallons/day mgd
mile mi
pound/square
inch (gauge) psig
square feet sq ft
square inches sq in
tons (short) ton
yard yd
0.405
1233.5
0.252
0.555
0.028
1.7
0.028
28.32
16.39
0.555(°F-32)*
0.3048
3.785
0.0631
0.7457
2.54
0.03342
0.454
3,785
1.609
(0.06805 psig +1)*
0.0929
6.452
0.907
0.9144
ha hectares
cu m cubic meters
kg cal kilogram - calories
kg cal/kg kilogram calories/kilogram
cu tn/min cubic meters/minute
cu m/min cubic meters/minute
cu m cubic meters
1 liters
cu cm cubic centimeters
°C degree Centigrade
m meters
1 liters
I/sec liters/second
kw killowatts
cm centimeters
atm atmospheres
kg kilograms
cu m/day cubic meters/day
km kilometer
atm atmospheres (absolute)
sq m square meters
sq cm square centimeters
kkg metric tons (1000 kilograms)
m meters
* Actual conversion, not a multiplier
*U.S. GOVERNMENT PRINTING OFFICE:1974 582-412/53 1-3
241
------- |