EP,
Development Document for Effluent Limitations Guidelines
and New Source Performance Standards for the
SOAP AND DETERGENT
Manufacturing
Point Source Category
APRIL 1974
U.S. ENVIRONMENTAL PROTECTION AGENCY
^\|^, < Washington, D.C. 20460
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^.
I
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DEVELOPMENT DOCUMENT
for
EFFLUENT LIMITATIONS
and
NEW SOURCE PERFORMANCE STANDARDS
SOAP AND DETERGENT MANUFACTURING
POINT SOURCE CATEGORY
Russell E. Train
Administrator
James L. Agee
Acting Assistant Administrator for Water and Hazardous Materials
Allen Cywin
Director, Effluent Guidelines Division
Richard T. Gregg
Project Officer
ApHI, 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. 20102 • Price $2.35
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ABSTRACT
This document presents the findings of an extensive study of the
soap and detergent manufacturing industry by Colin A. Houston and
Associates for the Environmental Protection Agency for the
purpose of developing effluent limitations guidelines, Federal
standards of performance, and pretreatment standards for the
industry to implement Sections 304, 306 and 307 of the Federal
Water Pollution Control Act Amendments of 1972.
Effluent limitations guidelines recommended herein set 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
application of 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 recommended herein set the degree of
effluent reduction which is achievable through application of the
best available demonstrated control technology, processes,
operating methods, or other alternatives.
The development of data and recommendations in the document
relate to the nineteen subcategories into which the industry was
divided on the basis of raw waste loads and appropriate control
and treatment technology. Separate effluent limitations are
proposed for each subcategory on the basis of raw waste load
control and end-of-pipe treatment achievable by suggested model
systems.
Supportive data and rationales for development of the proposed
effluent limitations guidelines and standards of performance are
contained in this report. Potential approaches for achieving the
limitations levels and their associated costs are discussed.
iii
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CONTENTS
Section Page
I CONCLUSIONS 1
General 1
Categorization 2
History and Source of Data 3
Integrated Plants 3
Potential Developments 4
II RECOMMENDATIONS 5
III INTRODUCTION 13
Purpose and Authority 13
Limitations Guidelines and Standards l1*
of Performance
General Description of the Industry 15
Historical 15
Companies and Markets 16
Industrial Cleaning Compounds 18
Sales and Production 19
Physical Plant 19
Trade Practices 19
Industry Problems 20
Future Trends 20
Soap Process Descriptions 20
Soap Manufacture by Batch Kettle 20
Fatty Acid Manufacture by Fat Splitting 2^
Soap From Fatty Acid Neutralization 26
Glycerine Recovery 29
Soap Flakes and Powders 31
Bar Soap 33
Liquid Soap 35
Detergent Process Descriptions 37
Oleum Sulfonation/Sulfation 38
Air-S03 Sulfation/Sulfonation 38
S03_ SoTvent and Vacuum Sul fonati on Ui
Sulfamic Acid Sulfation id
Chlorosulfonic Acid Sulfation Hi
Neutralization of Sulfuric Acid Esters U5
and Sulfonic Acids
Spray Dried Detergents U5
Liquid Detergents U7
Dry Detergent Blending U9
Drum Dried Detergents 1*9
Detergent Bars and Cakes 53
Formulations 53
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Section Page
IV INDUSTRY CATEGORIZATION 59
Introduction 59
Categorization 60
V WASTE CHARACTERIZATION 63
Introduction 63
Soap Manufacture by Batch Kettle 63
Fatty Acids by Fat Splitting 65
Soap by Fatty Acid Neutralization 66
Glycerine Recovery 66
Soap Flakes and Powders 68
Bar Soaps 68
Liquid Soaps 69
Oleum Sulfonation and Sulfation 69
Air-SOS Sulfonation and Sulfation 70
S03 SoTvent and Vacuum Sulfonation 71
SuTfamic Acid Sulfation 72
Chlorosulfonic Acid Sulfation 72
Neutralization of Sulfuric Acid Esters 73
and Sulfonic Acids
Spray Dried Detergents 7U
Liquid Detergent Manufacture 75
Detergent Manufacturing by Dry Blending 77
Drum Dried Detergents 7T
Detergent Bars and Cakes 77
VI POLLUTANT PARAMETERS 79
Introduction 79
Control Parameter Recommendations 79
Biochemical Oxygen Demand 79
Chemical Oxygen Demand 81
Suspended Solids 81
Surfactants (MBAS) 82
Oil and Grease 82
pH 83
Parameters Omitted 84
Nitrogen 84
Phosphorus and Boron 84
Scope of Parameter Measurements - 85
By Process
Soap Manufacture by Batch Kettle 85
Fatty Acids by Fat Splitting 86
Soap by Fatty Acid Neutralization 86
Glycerine Recovery 86
Soap Flakes and Powders 87
Bar Soaps 87
Liquid Soap 87
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Section Page
Oleum Sulfonation and Sulfation 88
Air-SOS Sulfation and Sulfonation 88
S03_ Solvent and Vacuum Sulfonation 88
Sulfamic Acid Sulfation 88
Neutralization of Sulfuric Acid Esters
and Sulfonic Acids 89
Spray Dried Detergents 89
Liquid Detergents 90
Dry Detergent Blending 90
Drum Dried Detergents 90
Detergent Bars and Cakes 90
Industrial Cleaners 90
VII CONTROL AND TREATMENT TECHNOLOGY 93
Introduction 93
Nature of Pollutants 94
Discussion of Treatment Techniques 95
Oil and Grease Removal 95
Coagulation and Sedimentation 98
Bioconversion Systems ^
Carbon Absorption Systems 9c
Filtration for Removal of Suspended 98
Solids
Dissolved Solids Removal 99
Other Treatment Technique Considerations 99
Special Operational Aspects of Control IOC
Technology
Solid Waste Generation Associated with 103
Treatment Technology
VIII COST, ENERGY AND NONWATER QUALITY ASPECTS 105
In-Plant Control 105
Impurities Removal 106
By-product/Degradation Product Control 107
Dilute Product from Cleanouts, Leaks 108
and Spills
End-of-Pipe Treatment l"p
Energy Requirements 113
Nonwater Quality Aspects 113
Implementation of Treatment Plans 114
IX BEST PRACTICABLE CONTROL TECHNOLOGY 117
CURRENTLY AVAILABLE
Introduction 117
Soap Manufacture by Batch Kettle 118
Fatty Acid Manufacture by Fat Splitting 123
Fatty Acid Hydrogenation 126
Soap from Fatty Acid Neutralization 126
Glycerine Recovery 127
Soap Flake and Powders 130
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Section Page
Bar Soaps 131
Liquid 133
Oleum Sulfonation and Sulfation 134
Air-S03_ Sulfation and Sulfonation 135
503 Solvent and Vacuum Sulfonation 137
SuTfamic Acid Sulfation 138
Chlorosulfonic Acid Sulfation 139
Neutralization of Sulfuric Acid Esters 140
and Sulfonic Acids
Spray Dried Detergents 142
Liquid Detergent Manufacture 146
Dry Detergent Blending 148
Drum Dried Detergents 149
Detergent Bars and Cakes 150
X BEST CONTROL TECHNOLOGY ECONOMICALLY 153
ACHIEVABLE
Introduction 153
Modified Soap Manufacture by Batch Kettle 155
Fatty Acid Manufacture by Fat Splitting 155
Glycerine Recovery and Concentration 159
Bar Soaps 162
Air-S03_ Sulfation and Sulfonation 166
S03 Solvent and Vacuum Sulfonation 166
SuTfamic Acid Sulfation 166
Chlorosulfonic Acid Sulfation 166
Spray Dried Detergents 166
Liquid Detergents 167
Detergent Bars and Cakes 167
XI NEW SOURCE PERFORMANCE STANDARDS 169
AND PRETREATMENT STANDARDS
Introduction 169
Soap Manufacture by Batch Kettle 171
Soap from Fatty Acid Neutralization 172
Bar Soap - Drying 173
Solvent Process for Soap Manufacture 173
Oleum Sulfation and Sulfonation 174
Air-S03_ Sulfation and Sulfonation 174
Pretreatment Requirements 183
Fats and Oils 183
Fats and Oils - Detergent Plants 184
Zinc 184
Industrial Cleaners 134
XII ACKNOWLEDGEMENTS 187
XIII REFERENCES 189
XIV GLOSSARY 195
Vlll
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TABLES
Page
Summary Value of Shipments at Manufacturers 17
Level Soaps and Detergents SIC 2841
2 Treatment Methods Used in Elimination of Pollutants 96
3 Relative Efficiency of Several Methods Used 97
in Removing Pollutants
4 Range of Water Use by Process 105
5 Cost and Energy Requirements Associated with 109
Various Treatment Methods
6 Cost of Sludge Conditioning and Disposal Operations 115
7-1 Best Available Technology Economically Achievable 153
Guidelines Reflecting No Change From Best Prac-
ticable Control Technology Currently Available
7-2 Best Available Technology Economically Achievable 154
Guidelines Reflecting Changes From Best Prac-
ticable Control Technology Currently Available
8 New Source Performance Standards Guidelines 170
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FIGURES
Number Title Page
1 Soap Manufacture by Batch Kettle 2?
2 Soap Making 25
3 Fatty Acid Manufacture by Fat Splitting 2?
4 Soap From Fatty Acid Neutralization 28
5 Glycerine Recovery 30
6 Soap Flakes and Powders 32
7 Bar Soaps 3^
8 Liquid Soap Processing 36
9 Oleum Sulfation and Sulfonation 39
(Batch and Continuous)
10 Air-S03^ Sulfation and Sulfonation ^0
(Batch and Continuous)
11 S03_ Solvent and Vacuum Sulfonation !»2
12 Sulfamic Acid Sulfation ^3
13 Chlorosulfonic Acid Sulfation M
14 Neutralization of Sulfuric Acid Esters H6
and Sulfonic Acids
XI
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Number Title Page
15 Spray Dried Detergents 48
16 Liquid Detergent Manufacture 50
17 Detergent Manufacture by Dry Blending 51
18 Drum Dried Detergent 52
19 Detergent Bars and Cakes 54
20 Composite Flow Sheet Waste Treatment 101
Soap and Detergent Industry
21 Sludge Solids Handling Soap and Detergent Industry 102
22 Waste Water Sources in Soap Manufacture 120
23 Fat Splitting 121
24 Fats Recovery System 125
25 Glycerine Concentration 128
26 Soap Manufacture by Batch Kettle: Modified 156
27 Modified: Fatty Acid Manufacture by Fat Splitting 157
28 Fatty Acids Manufacture: Hydrogenation Step, 158
If Carried Out
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Number Title Page
29 Glycerine Recovery 160
30 Concentration of 80% Glycerine to 99.5% 161
31 Continuous Detergent Slurry Processing Plant 176
High-Active Alkylate Sulfonation with Oleum
32 Continuous Detergent Slurry Processing Plant 177
Fatty Alcohol Sulfation with Oleum
33 Soap Manufacture by Continuous Saponification 178
34 Soap by Continuous Fatty Acid Neutralization 179
and Neat Soap Drying: For Bar Soaps
35 Combined Processes SOS Sulfonation/Sulfation- 180
Continuous and Neutralization of Sulfonic or
Alky! Sulfuric Acid Processes-Continuous
36 Fatty Alcohol Sulfation: With S03_ 181
37 Alpha-Olefin Sulfonation with S03_ 182
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SECTION I
CONCLUSIONS
General
The manufacturing of soaps and synthetic detergents represents a
minor source of water pollution. The industry uses approximately
15,160 million liters a year (or 4 billion gallons a year) as
process water. The pollutants emanating from its plants are
nontoxic and readily responsive to treatment. Some exceptions to
this statement exist in the industrial surfactant area and are
discussed in this report. More than 95 percent of plant
effluents go to municipal treatment plants with less than 5
percent classed as point sources.
Virtually all of the 5.8 billion kilograms (12.8 billion pounds)
of product estimated from these plants in 1973 is destined for
the nation's treatment plants and waterways; the intricacies of
the manufacturing processes of this industry warrant better
understand ing.
Soaps and detergents are performance products. (By dictionary
definition a detergent is a cleaning agent and includes ordinary
bar soap, which is classically based on natural fat. In popular
usage, however, the term detergent excludes soap, being
restricted to the family of cleaning compounds derived largely
from petrochemicals. This report follows popular usage.)
Literally thousands of chemical compositions can be formulated
which clean a surface. Detergents can be formulated with
entirely different organic and inorganic chemicals to exhibit the
same cleaning power or have the same biodegradability. They also
can be formulated to:
1. Maximize cleaning power
2. Maximize biodegradability
3. Minimize eutrophication potential in a specific recei-
ving water
U. Maximize cleaning power/unit cost
5. Minimize air or water pollutants and solid wastes
arising from the manufacturing processes.
Guidelines can be directed toward minimized water pollution from
manufacturing, but not to the extent of excluding consideration
of other factors. It is possible today to design formulas to
give almost zero discharge of pollutants from the manufacturing
process. However, the imposition of such low pollutant discharge
limits on water from the plants of the industry might result in
forcing radical reformulations with adverse effects in other
areas of environmental concern. For example, one formulation
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which would enable a zero discharge from a manufacturing plant
was voluntarily discarded by the industry 10 years ago because of
its poor biodegradability.
Categorization
For the purpose of establishing effluent limitation guidelines
and standards of performance, the soap and detergent industry can
be divided into 19 subcategories based on processes and products.
SOAP MANUFACTURE
PROCESS DESCRIPTION
Soap Manufacture - Batch Kettle and Continuous (101)
Fatty Acid Manufacture by Fat Splitting (102)
Soap From Fatty Acid Neutralization (103)
Glycerine Recovery (104)
Glycerine concentration (101A)
Glycerine Distillation (104B)
Soap Flakes & Powders (105)
Bar Soaps (106)
Liquid Soap (107)
DETERGENT MANUFACTURE
PROCESS DESCRIPTION
Oleum Sulfonation & Sulfation (Batch & Continuous) (201)
Air S03_ Sulfation and Sulfonation (Batch & Continu-
ous) (202)
S03 Solvent and Vacuum Sulfonation (203)
Sulfamic Acid Sulfation (20U)
Chlorosulfonic Acid Sulfation (205)
Neutralization of Sulfuric Acid Esters & Sulfonic
Acids (206)
Spray Dried Detergents (207)
Liquid Detergent Manufacture (208)
Detergent Manufacturing By Dry Blending (209)
Drum Dried Detergents (210)
Detergent Bars & Cakes (211)
The code numbers shown after the processes are used to identify
them throughout this report.
These subcategories cover the major unit operations of the soap
and synthetic detergent industry as it is established in the
Federal Standard Industrial Classification Manual, Industry Code
Number 2841. Some special processes in the production of
surfactants have been omitted, namely:
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Amine Oxides Quaternaries Isethionates
Amides Alkyl Glyceryl Ether Hydrotropes
Taurides Sulfonates
The categories covered in this report allow the permit granting
authority to identify the unit operations in a soap and detergent
plant and the important measurable effluents associated with
each. Where several units are present in the same plant, the
permit granting authority can establish a maximum permissible
effluent standard for a given plant by adding the effluent
allowable from each unit. Where a large number of units are
grouped together in a single plant it is possible to reduce the
total permissible effluent that would be arrived at simply by
adding the individual units in that site. Techniques for such
reduction are covered in the body of this report.
HIgTORY_AND SOURCE OF DATA
When the study was initiated on January 16, 1973, there were no
detailed effluent studies available on this industry. A
literature search including previous EPA and state work yielded
little useful data. The Corps of Engineers permit applications
yielded little correlatable data since information as to the
products produced and any relationship of product or processes to
effluent flows was lacking. Another problem then arose when it
was found that the soap and detergent companies possessed little
or no detailed data regarding their effluent flows. Most
effluent data from the companies turned out to be on combined
sewers (combining the effluent of three to ten process units) and
hence were of limited value. Therefore, the sample program
orginally conceived by the EPA and Contractor as a program to
verify literature and company-provided information had to be
enlarged and turned into a major research project. Though a
relatively sound data base was obtained, ideally such data should
be obtained by composite sampling over a period lasting from
thirty days to a year. Because of the great pressure to complete
this work to enable the EPA to publish guidelines October 18,
1973, as called for in the Act, Public Law 92-500, it was
impossible to run any composite program longer than one week. A
number of the sample programs initiated are being continued
voluntarily by the companies, and more sophisticated information
has begun to come in.
For publication of this report, it was necessary to foreclose use
of further data June 15, 1973. The data flow is expected to
continue and, after collation, is being turned over to the EPA as
received. A major conclusion stemming from this work is the
recognition of the necessity of arranging for a long term EPA
depository for industry effluent data so that water handling
problems can be fairly and inventively dealt with.
Integrated Plants
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An important, conclusion reached in this study was that integrated
plants having a group of several unit processes at the same plant
site have a substantial advantage in their ability to minimize
pollution by cascading water and working off the by-products from
one process into another unit process step. Although we have
indicated many places where we believe the permit writer should,
for this reason, apply more lenient standards to the small one or
two unit process plant, this is really an area needing case by
case evaluation.
Potential Developments
This report is written around soaps and synthetic detergents as
formulated in 1973. From a national treatment standpoint, and to
lessen the possible eutrophication impact of soap and detergent
formulas, it may be necessary to change the 1973 formulas
considerably. Such changes will result in different effluents
from the production units. In the soap and glycerine field,
changes in formulation are not likely to be very pronounced, but
they are in detergent bars, powders and liquids. Substantial
changes in effluents from unit processes and hence detergent
plants may be necessary to minimize ecological impact of the end
product in specific receiving watersheds. Particularly in this
industry, the guidelines need to be reviewed periodically to
adjust to improvements in formulas.
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SECTION II
RECOMMENDATIONS
As a result of the findings of this report the following
recommendations are made:
1. That the effluent limitations and standards of performance be
based on the level of waste reduction attainable as an average
for a thirty day period with the following values established for
the designated segments of the industry. (All values are given
in terms of kilograms (kg) of pollutant per kkg of the anhydrous
product produced in the numbered process given. As all values
express weight to weight ratios the units are interchangeable and
Ib can be substituted for kg. For example, 0.6 kg BOD5 per kkg
of product is an identical ratio to 0.6 Ib BOD5 per 1000 Ib of
product.)
Best Practicable Control Technology Currently Available
Suspended Oil &
Subcategory BOD5 COD Solids Surfactants Grease
Soap Manufacture 0.60 1.50 0.40 NA 0.10
Batch Kettle
Fatty Acid 1.20 3.30 2.20 NA C.30
Manufacture By
Fat Splitting
Hydrogenation 0.15 0.25 0.10 NA 0.10
Soap From Fatty 0.01 0.05 0.02 NA 0.01
Acid Neutrali-
zation
Glycerine Con- 1.50 4.50 0.20 NA 0.10
centration
Glycerine Dis- 0.50 1.50 0.20 NA 0.10
tillation
Soap Flakes 0.01 0.05 0.01 NA 0.01
and Powders
Bar Soaps 0.34 0.85 0.58 NA 0.04
Liquid Soaps 0.01 0.05 0.01 NA 0.01
Oleum Sulfona- 0.02 .09 0.03 0.03 C.07
tion & Sulfa-
tion (Batch 6
Continuous)
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Air-S03 Sulfa- 0.30 1.35 0.03 0.30 0.05
tion S Sulfona-
tion (Batch &
Continuous)
SO3 Solvent G 0.30 1.35 0.03 0.30 0.05
Vacuum Sulfona-
tion Sulfamic
Acid Sulfation 0.30 1.35 0.03 0.30 0.05
Chlorosulfonic 0.30 1.35 0.03 0.30 0.05
Acid Sulfation
Neutralization 0.01 0.05 0.03 0.02 0.01
of Sulfuric Acid
Ester 8 Sulfonic
Acids
Spray Dried 0.01 0.05 0.01 0.02 0.005
Detergents
(normal)
Spray Dried 0.08 0.35 0.10 0.15 0.03
Detergents
(air restrictions)
Spray Dried 0.02 0.09 0.02 0.03 0.005
Detergents
(fast turnaround)*
Liquid Deter- 0.20 0.60 0.005 0.13 0.005
gent Manufacture
Liquid Deter- 0.05 0.15 0.002 0.04 0.002
gent Manufacture
(fast turnaround) **
Detergent Manu- 0.01 0.07 0.01 0.01 0.005
facturing by
Dry Blending
Drum Dried 0.01 0.05 0.01 0.01 0.01
Detergents
Detergent 0.70 3.30 0.20 0.50 0.02
Bars & Cakes
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* Allowance for each turnaround in excess of six in a 30-day period.
** Allowance for each turnaround in excess of eight in a 30-day period.
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Best Available Technology Economically Achievable
Suspended Oil &
Subcategory BOD5 COD Solids Surfactants Grease
Soap Manufacture 0.40 1.05 0.40 NA 0.05
Batch Kettle
Fatty Acid Manu- 0.25 0.90 0.20 NA 0.15
facture by Fat
Splitting
Hydrogenation 0.15 0.25 0.10 NA 0.10
Soap From Fatty 0.01 0.05 0.02 NA 0.01
Acid Neutrali-
zation
Glycerine Con- 0.40 1.20 0.10 NA 0.04
centration
Glycerine Dis- 0.30 0.90 0.04 NA 0.02
tillation
Soap Flakes 0.01 0.05 0.01 NA 0.01
and Powders
Bar Soaps 0.20 0.60 0.34 NA 0.03
Liquid Soap 0.01 0.05 0.01 NA 0.01
Oleum Sul- 0.02 0.09 0.03 0.03 0.07
fonation &
Sulfation
(Batch &
Continuous)
Air-SO3 Sul- 0.19 0.55 0.02 0.18 0.04
fation and
Sulfonation
(Batch & Con-
tinuous)
S03 Solvent 0.10 0.45 0.01 0.10 0.02
and Vacuum
Sulfonation
Sulfamic Acid 0.10 0.45 0.01 0.10 0.02
Sulfation
Chlorosulfonic 0.15 0.75 0.02 0.15 0.03
Acid Sulfation
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Neutralization 0.01 0.05 0.03 0.02 0.01
of Sulfuric Acid
Esters 6 Sulfonic
Acids
Spray Dried 0.01 0.04 0.02 0.02 0.005
Detergents (normal)
Spray Dried 0.06 0.25 0.07 0.10 0.02
Detergents (air
restrictions)
Spray Dried 0.02 0.07 0.02 0.02 0.005
Detergents (fast
turnaround)
Liquid Deter- 0.05 0.22 0.005 0.05 0.005
gent Manufacture
Liquid Deter- 0.02 0.07 0.002 0.02 0.002
gent Manufacture
(fast turnaround)
Detergent Manu- 0.01 0.07 0.01 0.01 0.005
facturing by
Dry Blending
Drum Dried 0.01 0.05 0.01 0.01 0.01
Detergents
Detergent Bars 0.30 1.35 0.10 0.20 0.02
6 Cakes
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Standards of Performance for New Sources
Suspended oil &
Subcategory BOD5 COD Solids Surfactants Grease
Soap Manufacture 0.40 1.05 0.40 NA 0.05
Batch Kettle
Fatty Acid 0.25 0.90 0.20 NA 0.15
Manufacture by
Fat Splitting
Hydrogenation 0.15 0.25 0.10 NA 0.10
Soap From Fatty 0.01 0.05 0.02 NA 0.01
Acid Neutralization
Glycerine Con- O.UO 1.20 0.10 NA O.OU
centration
Glycerine Dis- 0.30 0.90 0.04 NA 0.02
tillation
Soap Flakes & 0.01 0.05 0.01 NA 0.01
Powders
Bar Soaps 0.20 0.60 0.34 NA O.C3
Liquid Soap 0.01 0.05 0.01 NA 0.01
Oleum Sulfonation 0.01 0.03 0.02 0.01 0.04
& Sulfation (Batch
& Continuous)
Air-S03 Sulfa- 0.09 0.40 0.02 0.09 0.02
tion 6 Sulfona-
tion (Batch &
Continuous)
SO3 Solvent & 0.10 0.45 0.01 0.10 0.02
Vacuum Sulfonation
Sulfamic Acid 0.10 0.45 0.01 0.10 0.02
Sulfation
Chlorosulfonic 0.15 0.75 0.02 0.15 0.03
Acid Sulfation
10
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Neutralization of 0.01 O.OU 0.03 0.02 0.01
Sulfuric Acid
Esters 6 Sulfonic
Acids
Spray Dried 0.01 0.04 0.02 0.02 0.005
Detergents (Normal)
Spray Dried 0.06 0.25 0.07 0.10 0.02
Detergents (Air
restricted)
Spray Dried 0.02 0.07 0.02 0.02 0.005
Detergents (Fast
turnaround)
Liquid Detergent 0.05 0.22 0.005 0.05 0.005
Manufacture
Liquid Detergent 0.02 0.07 0.0002 0.02 0.002
Manufacture (fast
turnaround)
Detergent Manu- 0.01 0.07 0.01 0.01 0.005
facturing by
Dry Blending
Drum Dried 0.01 0.05 0.01 0.01 0.01
Detergents
Detergent Bars 0.30 1.35 0.10 C.20 0.02
6 Cakes
The pH of final discharge(s) should be within the range of
6.0-9.0 at all times.
2. For purposes of monitoring and enforcement, periods and
values other than those for the 30-day average should be adopted.
Daily maximums 3 times and 2 times the 30-day averages are
recommended as reflecting reliability of control and treatment
for best practicable and best available control
3. A continuing effort is recommended to further study the waste
water effluent problems of the soap and detergent field,
particularly detergents. The technology is in a state of rapid
flux and merits close observation.
Basically two areas should be considered:
(a) Changes in detergent formulations and how they affect
wastes associated with manufacture and the environmental
11
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impact resulting from use by the consumer.
(b) Control and treatment practices as they affect
water pollution, air pollution, and solid waste.
12
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SECTION III
INTRODUCTION
Purpose and Authority
Section 301 (b) of the Act requires the achievement by not later
than July I/ 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 eco-
nomically 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) of 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 economically 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 soap and
detergent industry.
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 soap and detergent category,
which was included within the list published January 16, 1973.
13
-------
Limitations Guidelines and Standards of Performance
The effluent limitations guidelines and standards of performance
proposed herein were developed in the following manner. The
point source category was first categorized for the purpose of
determining whether separate limitations and standards are
appropriate for different segments within a point source
category. Such subcategorization was based upon raw material
used, product produced, manufacturing process employed, and other
factors. The raw waste characteristics for each subcategory were
then identified. This included an analysis of (1) the source and
volume of water used in the process employed and the sources of
waste and waste waters in the plant; and (2) the constituents
(including thermal) of all waste waters including toxic constitu-
ents and other constituents which result in taste, odor, and
color in water or aquatic organisms. The constituents of waste
waters which 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 was identified. This included an
identification of each distinct control and treatment technology,
including both inplant 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 (including thermal) 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 was also identified. In addition, the non-
water quality environmental impact, such as the effects of the
application of such technologies upon other pollution problems,
including air, solid waste, noise and radiation were also iden-
tified. The energy requirements of each of the control and
treatment technologies was identified as well as the cost of the
application of such technologies.
The information, as outlined above, was then evaluated in order
to determine what levels of technology constituted the "best
practicable control technology currently available," "best
available technology economically achievable" and the "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 quality
environmental impact (including energy requirements) and other
factors.
-------
The data for identification and analyses were derived from a
number of sources. These sources included EPA research
information, published literature, a voluntary industrywide
audit, an extensive industry plant effluent sampling program,
qualified technical consultation, and on-site visits and
interviews at exemplary soap and detergent processing plants
throughout the United States. All references used in developing
the guidelines for effluent limitations and standards of
performance for new sources reported herein are included in
Section XIII of this document.
General Description of the Industry
This industrial category is covered under Standard Industrial
Code 2841 and includes establishments primarily engaged in the
manufacture of soap, synthetic organic detergents, inorganic
alkaline detergents, or any combination. Crude and refined
glycerine from vegetable and animal fats and oils are also
included. Excluded from this category are establishments
primarily engaged in manufacturing shampoos or shaving products
and synthetic glycerine. Also excluded are specialty cleaners,
polishing and sanitation preparations.
Historical
The industry which produces products for cleaning of fabrics,
dishes, and hard surfaces goes back to the earliest recorded
history. Clay tablets found in ancient Mesopotamia dating back
to the third millenium B.C., gave a soap recipe calling for a
mixture of potash and oil to be used in the making of cloth.
Modern soap and synthetic detergent formulations and business
practices were shaped by a series of events which started in the
1930s. These include the introduction of synthetic surface
active ingredients in the mid 1930s. There followed the war-
induced shortage of the natural ingredients for soap making such
as tallow and coconut oils and the consequent rapid increase then
in the use of synthetics.
The discovery of polyphosphate builders followed, which made
synthetic laundry products suitable replacements for soap. The
scramble of soap and detergent companies for the housewives'
favor occurred during the 1950s and determined market shares of
companies in the household segment even today. Finally, there
began the formulation of detergent products to meet environmental
considerations.
The first environmental reformulation consisted of a voluntary
industry switchover to more biodegradable linear benzene
sulfonate surfactants to replace the original highly branched,
poorly degradable benzene sulfonates in the 1960s. Shortly
thereafter the use of phosphate builders in detergents came under
attack from environmentalists. Of the 3 nutrients, phosphorus,
nitrogen and carbon, which cause eutrophication of lakes,
phosphorus appears to be the only nutrient amenable to control.
15
-------
A series of events led to today's confusing and indeterminate
situation vis-a-vis phosphate builders. Nitrilotriacetic acid
use was begun and then stopped because of fears over
teratogenicity. Detergents built with carbonates and silicates
were introduced and then somewhat squelched because some of the
products represented alkalinity hazards and there were also
problems such as interference with flame retardancy, and
deposition of hard water reaction products on clothes. Today the
search for a safe, effective builder to replace phosphate
continues in full swing with citrates and multifunctional
compounds such as carboxy methylene oxy succinate getting much
research effort. Other detergent ingredients have also been the
subject of concern as to their safety and environmental impact.
Enzymes are an example, and sales of enzyme-containing detergents
suffered for a time as a result.
Companies and Markets
The household detergent industry is dominated by three large
companies. The largest U.S. company has about one half of the
U.S. sales and production. The next two companies in size each
have about one sixth of the U.S. market. The remaining 17
percent of the business is shared by over 300 companies. Very
few companies beyond the five largest produce and market products
across the country. The smaller companies captured an
appreciable portion of the market share of the big three with
non-phosphate detergents before bad publicity put a damper on
sales of phosphate-free laundry detergents.
Laundry detergents are the largest category of products made by
the soap and detergent industry. The number one selling brand
has held about a 25 percent share of the U.S. market for over two
decades. This brand is the industry standard for this category
of product and the market leader fights hard to maintain his
level of sales of household detergents. Other detergent
companies constantly search for improved products containing
better ingredients so they can get a bigger share of this market.
The cost of the search for new and improved products has
increased greatly because of the more sophisticated safety and
environmental approaches now needed.
In considering other household cleaning products, it will be
noted that the big three producers have a less dominant position.
Liquid hand dishwashing detergents are next to laundry detergents
in importance. Although the largest companies do dominate this
market there are many private label products sold by supermarket
chains and also quite a number of brands marketed by smaller
companies. The liquid hand dishwashing detergent market is
static in growth because of the constant shift toward home
automatic dishwashers.
Automatic dishwashing detergents are produced in sizable amounts
by medium and small sized firms as well as the larger detergent
companies. This category of product has grown very rapidly with
16
-------
TABLE 1
SUMMARY VALUE OF SHIPlENrS AT MANUFACTURERS LEVEL
SOAPS AND DETERGENTS SIC 2841
AFTER 1967 CENSUS OF MANUFACTURERS (ADJUSTED)
1963 1967 1973
(in millions) (in millions) (in millions)
Kilogratis Pounds Dollars Kilogiaiis Pounds Dollars Kilograms Pounds Dollars
All Soaps 605.1 1332.a 355.U 553711240.3 383.9540.41190.4 415.1
Glycerine
Natural 63.6 140.0 26.0 65.8 145.0 36.0 68.1 150.0 35.0
Alkali
Detergents 519.0 1143,2 200.2 670.1 1476.0 279.6 887.6 1955.0 384.5
Acid Type
Cleaners 156.1 343.8 35.2 256.1 564.0 61.7 398.6 878.0 100.7
Synthetic
Ore. Det.
Household 2098.7 4622.7 1029.4 2513.5 5536.4 1235.4 3169.9 6982.2 1565.0
Synthetic Ore.
Det. Non-
Household 287.2 632.6 115.3 357.5 787.4 141.1 443.1 976.0 167.0
Soap and Other
Det. NSK 38.6 85.0 17.6 166.2 366.0 73.2 332.3 732.0 146.4
Grand Total
Soaps and
Detergents 3768.3 8300.1 1778.7 4592.3 10115.1 2210.9 5840.1 12863.6 2813.7
-------
the proliferation of the home automatic dishwasher. With only a
third of the nation's households having automatic dishwashers
great growth can be expected to continue.
Household specialty cleaners of all types are produced by
hundreds of companies in successful competition with the big
three. This is possible because the specialties require less
capital investment than spray dried laundry detergents. Also,
specialties are amenable to smaller and localized marketing and
advertising programs.
As opposed to the production of detergents, the soap producing
segment of the industry is now concerned primarily with the
production of toilet bars. A modest amount of soap is used in
synthetic household detergent manufacture, both in heavy duty
solid formulations and in combination detergent - soap bars.
There is a possibility of a moderate increase in the marketing of
laundry soap if more local ordinances prohibiting the use of
detergents were to be passed. For a number of economic reasons,
for example, the doubling of the cost of natural fats and oils
used in soap manufacture within the last year alone, it seems
unlikely that soap sales will increase significantly from their
present levels.
The largest sales of bar soaps are again made by the three
largest companies. In general, other soap companies specialize
in private label, specialty soaps, and institutional sales.
Glycerine is an important product of the industry. It is made as
a by-product of soap production, and synthetically from
petroleum-derived propylene. Glycerine is an important cosmetic
and food intermediate and many soap and detergent companies are
also in these businesses. Synthetic glycerine competes with the
naturally derived product. Its synthesis bears no relationship
to the fat-derived product, but in composition it is essentially
identical.
Glycerine is a mature chemical whose use is presently growing at
the rate of 3 percent a year. The total 1972 estimated U.S.
production was 158 million kilograms (3U8 million Ib) with
exceptionally high exports accounting for 29 million kilograms
(64 million Ib). Synthetic glycerine (not included in SIC 2841)
is estimated to have accounted for approximately 91 million
kilograms (200 million Ib) of the total production in 1972 with
natural glycerine production accounting for 68 million kilograms
(150 million Ib). There are 3 new fat splitting plants under
construction in the U.S. which will give 3 new sources of by-
product glycerine.
Industrial Cleaning Compounds
Industrial cleaning compounds are also an important part of this
industry. Compounds are made for metal cleaning, textile
processing, food sanitation, and a host of other applications.
18
-------
Total dollar value of the non-household cleaning market was $263
million in 1967 and is estimated at $373 million for 1973. There
are a host of small companies and divisions of large companies in
this business area. Most producers, though, serve a limited
market and a limited geographical area.
Sales and Production
Table I gives an estimate of dollar values and poundage produced
for the products comprising SIC 2841. It is interesting that the
oldest product, soap, still securely retains an important market;
that is, toilet and bath bars. Automatic dishwashing detergents
are growing rapidly and these products are even more vitally
affected by the phosphate controversy than are laundry
detergents.
Physical Plant
In general, the soap and detergent industry has not integrated
backwards toward their raw materials. Basic raw materials come
from a host of supplier companies. Caustic, fats, and oils for
soap making come from chemical and agricultural processors,
although some companies do own coconut plantations. Detergent
alkylate, alcohols and non-ionic surfactants usually come from
large chemical and petrochemical companies. Some anionic
surfactant is also produced by suppliers, but in general the soap
and detergent companies do, most of their own sulfation and
sulfonation. The inorganic builders and other additives come
exclusively from supplier companies.
The three largest companies in the household market have plants
in major metropolitan areas across the country. Not only are
distribution costs important, but also the large volume of
products makes it possible for one company to build economical
sized plants in a number of locations. There are about 30 major
plants for production of heavy duty laundry detergents in the
United States.
Trade Practices
It is fairly common for the major companies to contract with
other companies for toll processing. In these arrangements the
soap and detergent company will buy synthetic detergent bases,
send them to a second company for reaction, and have the product
returned for further compounding. For example, detergent
alcohols may be bought by a soap and detergent company and then
toll ethoxylated by a petrochemical company and returned to the
soap and detergent company for further processing.
Another business arrangement is the production of packaged
detergents by private label producers which are then sold by the
major food chains under their own brand names.
19
-------
The capital requirements for a spray dried detergent bead plant
limit the number of these units. To be competitive, these
complexes produce volumes on the order of 13,620 kg per hour
(30,000 Ib per hour) and cost up to 10 million dollars. Soap
making equipment can be fairly capital intensive, especially the
newer fat splitting and fatty acid purification processes.
Production of light-duty liquid detergents and dry blended
products require less capital and consequently many more
producers are found. Freight is an important consideration in
shipping liquids.
Industry Problems
Foremost in difficulty is the phosphate problem. Large sums of
money have been spent both by detergent companies and by their
suppliers to find phosphate replacements. To date, no
replacement has been found which is entirely safe, effective, and
economically feasible. Generally, companies are reformulating
with lower phosphate levels, substituting nonionic for anionic
organic surfactants, and using additional amounts of alkaline
builders like sodium carbonate and sodium silicates.
New product development is not as frequent and fruitful as in the
past. It is much more difficult to produce new products which
meet environmental requirements, so development money leads to
fewer products.
An appreciable portion of the waste load encountered in soap and
detergent manufacturing is attributable to general practices
within the industry. The industry is strongly oriented to sales
promotion, with sales promotion frequently pitched to emotion or
aesthetic factors which have little or no affect on product
performance. This has led to great variety in things such as
color, scent and opacity which produce the need for frequent
cleanouts to avoid cross contamination and result in generation
of added waste loads.
Future Trends
The industry is growing at a rate of 5 percent per year. It is
secure in the knowledge that its products are vitally necessary.
The relative standing of various industry members depends upon
how successfully they solve environmentally actuated formulation
problems.
SOAP_PROCESS DESCRIPTIONS
Each of the following process descriptions are associated with a
process flow sheet. All of the expected waste water effluents
are identified in the flow sheet by name and code number for
quick reference.
SOAP MANUFACTURE BY BATCH KETTLE (101)
20
-------
Most of the soap made by this process finds its way into toilet
bar form for household usage. This use demands freedom from
offensive odors, and displeasing colors. In order to meet this
requirement, the starting fats and oils must be refined. There
is a direct relationship between quality of the fats and the
quality of the finished soap.
Fat Refining and Bleaching
There are several ways in which fats are refined. One of the
most frequently used methods employs activated clay as the ex-
traction agent. Activated clay, having a large ratio of surface
area to weight, is agitated with warm oil and filtered. Color
bodies, dirt, etc., are removed, usually through a plate and
frame press. The clay is disposed of as solid waste. A small
amount of clay remains in the refined fat.
The clay is often "activated" by being given an acid treatment
itself by the clay supplier and is a source of sulfate ion build-
up in some soap recycling streams.
Other ways in which fats are refined include caustic extraction,
steam stripping and proprietary aqueous chemicals.
When soap accounted for the major portion of the soap and
detergent market, the Solexol process of extraction found use in
refining of fats and oils. The design of this liquid propane
extraction process is based on the diminishing solubility of fats
in liquid propane with increasing temperature. The fats are
completely miscible at 48.84 C (120 F) but become almost
insoluble at 82.14 C (180 F) and most of the color bodies
precipitate.
Color bodies fall to the bottom of the treating tower while
decolorized oils dissolved in liquid propane sit on the solvent
(liquid propane) layer and are recovered from the top. This
process is not now used in the United States, but should be
reexamined since it offers a way to eliminate water use and thus
could again become economical as discharges must be reduced.
Soap Boiling
Although a very old process, kettle boiling still makes a very
satisfactory product and in several well integrated manufacturing
plants this process has a very low discharge of waste water
effluents.
Making a batch of neat soap (65 - 70 percent soap in water) can
take as long as four to six days to complete. A series of large
steel tanks are used in a counter current manner to "boil" soap.
Their capacity can be as high as 54,480 kilograms (120,000
pounds) of ingredients. Ever weakening caustic streams are met
by enriched fat so that the caustic is essentially exhausted in
the presence of fresh fat. In actual practice the fat never
21
-------
101 SOAP MANUFACTURE BY BATCH KETTLE
1011
RECEIVING
STORAGE-TRANSFER
1012 FAT REFINING
AND BLEACHING
1013 SOAP BOILING
— STEAM
/• STEAM
NaOH
STEAM-
SALT
SALT.
~1
FATTY ACIDS
LOW GRADE
SOAP SALES
«^-
-*•
— »•
SOAP
BOILING
KETTLE
^
1
1
NIGRE
PROCESSING
1
1
rn
NEAT SOAP TO
*" PROCESSING
AND SALE
GLYCERINE TO
*" RECOVERY
^ LOW GRADE SOAP
LOW GRADE
FATTY ACID
O
c
pa
WASHOUTS
101102
\
WASTEWATER I
101231 |
I
\
SOLID WASTE
101209
1
t
BAROMETRIC
CONDENSATE
101218
SEWER LYES
101319
BRINE AND ACID
WASTEWATER
101320
-------
leaves the tank in which it starts until it is converted into
neat soap. Just the aqueous caustic stream flows from tank to
tank.
A simplified process description for kettle boiling soap follows:
Step 1
weigh in
fats 6 oils
and alkali
Step 5
drain off
spent lye
and send to
recovery
Step 9
add water
and heat to
close soap
for filling
change
Step 2 Step 3
turn on add salt and
steam and saponify boil for
graining
Step 6
add water to
kettle and
boil closing
Step 10
settle and
draw off
neat soap
Step 7
add strong
alkali to
closed soap
Step 11
recycle
bottom nigre
to Step 1
Step 4
turn off
steam and
settle
Step 8
settle
and run
off lye
to Step 1
Neat Soap
Step 1 - Fats and oils are weighed in. The caustic stream from
the "extreme change" of step 7 is run in as well as the nigre
from step 11.
Step 2 - Live steam is customarily released into the kettle where
it not only heats up the materials but also performs the stirring
function. About three or four hours are consumed in this step.
StejD_3 - Graining is the act of separating the newly formed soap
from the exhausted lye solution. An operator adds salt or salt
solution until a sample withdrawn with a trowel separates
distinctly into soap and lye. About 10 - 12 percent Nad is
required.
Step 4 - About four hours are needed to completely settle the
contents into two layers.
Step 5 - The spent lye contains 7 -
sent to the glycerine recovery unit.
8 percent glycerine and is
Step 6 - "closed soap" is now made by adding fresh water to the
kettle and heating it to make a continuous creamy material,
dissolving the remaining glycerine and salt.
Step 7 - The "strong change" is carried out by adding fresh,
concentrated lye which saponifies the last remnants of fat. The
batch is brought to a boil again, water is added until the soap
23
-------
is closed, then the lye is run in. Since the soap is not soluble
in the strong alkali it becomes grainy.
Step 8 - Steam is shut off and the batch allowed to settle for
three hours. The lye is run off and added to a beginning batch
in the "extreme kill."
Step 9 - Heating is again begun and water run in until the mass
is closed and boiling is continued until the soap removed on a
trowel can be poured off in a transparent sheet.
Step 10 - Heat is turned off and the batch is allowed to settle.
Neat soap is drawn off the top and run off to be processed into
one of many forms of soap products. The lower layer is the nigre
which contains the color bodies, dark soap, etc. It contains as
much as 20 - 25 percent of the kettle contents (30 - UO percent
soap). When the nigre becomes heavily loaded with impurities it
can itself be salted out, making a low grade soap for sale.
Step._ll - Frequently the nigre is recirculated to the kettle for
the start of a new batch.
An overall schematic of the soap-making process is as follows:
The waste water from kettle boiling is essentially from the nigre
stream. The nigre is the aqueous layer which contains the color
bodies generated in the soap making process, mostly dark soaps.
They are often marketed as industrial lubricants or low grade
special purpose soaps. Where such a market can be established a
kettle boil soap process is already at the zero discharge
effluent level except for the oil refining step.
Salt_Usage
In order to maintain suitable solubility for proper processing,
salt is added to the soap making process to maintain the required
electrolytic balance. Most of the salt charged into the process
is ultimately returned to it from the glycerine concentration
step, which will be discussed later. Practically every kettle
boiling soap manufacturer concentrates his glycerine stream,
although only a few go on to the distillation of glycerine.
FATTY ACID MANUFACTURE BY FAT SPLITTING (102)
By means of fat splitting very low grade fats and oils are
upgraded to high value products by splitting the glycerides into
their two components, fatty acids and glycerine. Fat splitting
is an hydrolytic reaction which proceeds as follows:
Fat + Water —> Fatty Acid + Glycerine
Using a Twitchell catalyst (an aromatic sulfonic acid) and a long
residence time, fats can be split at nearly atmospheric
21*
-------
f
Kettle Boil
Nigre
Dark soap
to market
Spent lye
Evaporator!
Concentrated
glycerine
Salt
SOAP MAKING
FIGURE 2
-------
pressures. Today, however, most fat splitting takes place in a
high pressure, high temperature tower operated at around 34 atm
and 260°C (500 psig and 500°F).
Heated fat, 254°C (490°F) and under pressure, is fed into the
bottom of the tower and water, 204°C (400°F) and also under
pressure, is fed into the top. The two streams mix counter-
currently and hydrolysis takes place, often in the presence of a
zinc or tin catalyst. At the high temperatures employed the fat
is soluble to the extent in 12 - 25 percent of water, depending
upon which fat is used.
In about 90 minutes the splitting can be as high as 99 percent
complete. The glycerine by-product can be produced at a variety
of concentrations depending upon how complete a fat hydrolysis is
desired. More concentrated glycerine can be provided at some
expense of fatty acid yields.
The crude acids are flashed in a pressure reducer and then
distilled at 0.0026 - 0.0039 atm (2-3 mm) pressure. The
resulting product may be subjected to an additional process step
of flash hydrogenation to reduce the amount of unsaturated acids.
SOAP FROM FATTY ACID NEUTRALIZATION (103)
Soap making by fatty acid neutralization exceeds the kettle boil
process in speed and minimization of waste water effluent.
Although widely used by the large soap producers, it is- also very
popular with the smaller manufacturer.
This route from the acids is faster, simpler (no by-product
dilute glycerine stream to handle) and "cleaner" than the kettle
boil process. Distilled, partially hydrogenated acids are
usually used.
The fatty acid neutralization process has several additional
advantages over the kettle boiling process. It does not have a
large salt load to recycle, and has a free alkali concentration
in the order of 0.1 - 0.2 percent, contrasted with around 1
percent in the kettle boiling process.
The reaction that takes place is substantially:
Caustic + Fatty Acid Soap
Often, sodium carbonate is used in place of caustic with the
attendant evolution of carbon dioxide. When liquid soaps (at
room temperature) are desired, the more soluble potassium soaps
are made by starting with potassium hydroxide. The potassium
soaps are used in the familiar liquid hand soap dispensers, in
many industrial applications, and often as lubricants.
As in kettle boiling soap manufacture, the most popular mix of
acids for bar soap is in the ratio of 20:80 20/80 coconut
26
-------
102 FATTY ACID MANUFACTURE BY FAT SPLITTING
1021 RECEIVING
STORAGE-TRANSFER
1022 FAT PRETREATMENT
1023 FAT SPLITTING
1024 FATTY ACID DISTILLATION
ro
FATS AND
OILS
CLAY
CATALYST-
-1
n
n
k
CRUDE
FAT AND
OIL ,
X
x"
| >VTO FAT
1 SPLITTING
*
*J
M
WASTEWATER
W22OI
" TREATING
VESSELS
SPENT
CLAY
FOOTS
\
j RECOVERY L
I
I
SOLID WASTE
W22O9
i
i
i
REFINED FATS
AND OILS
STEAM
CATALYST —
FATTY ACIDS
- AND SOAPS
WASHINGS
102221
PRESSURE
r REDUCTION j
, REACTOR I |
<
PRESSURE I
1 — REDUCTION
1
hATTY
ACIDS
STE/
HYDROGEN
CATALYST-
M
CAUSTIC SODA
SULFURIC ACID-
fCBUDE
GLYCERINE
TO RECOVE
PROCESS CONDENSATE
1O2322
RY
STILL
1
-, BAROMETRIC
CONDENSER
FATTY ACIDS
"! .__ * 1
RESI
— i
i
*
' HYDHO-
GENATION
MULSION BREAKINC
AT SEPARATION
EUTRALIZATION
1
COOLING TOWER
SLOWDOWN
W24O4
'
=f
i
i
i
-?
;(
f
1
1
*
-STEAM
REFINED
FATTY ACIDS
FATTY ACID
h PITCH AND
RESIDUES
BAROMETRIC
CONDENSATE
102418
SPENT CATALYST
AND WATER WASHINGS
102423
-------
ro
oo
103 SOAP FROM FATTY ACID NEUTRALIZATION
1031 RECEIVING
STORAGE-TRANSFER
1032 SAPONIFICATION
1033 RECYCLE-REPROCESSING
CAUSTIC SODA — —
SODA ASH
x
'
1
LEAKS, SPILLS, STORM
RUNOFFS, WASHOUTS.
103102
MIXER
*
L>
WASTEWATER BRINES
103224
WASHOUTS I
103202
SOAP TO
•»• STORAGE •
REACTOR
1
1
1
1
i
1
1
1
1
1
1
1
U-
1
\
1
l_
•*-•
•*—
OFF QUALITY SOAP
TO LANDFILL 103325
WASHOUTS
103302
- SCRAP SOAP
— CAUSTIC SODA
1
1
1
*
SEWER LYES
103326
FIGURE
-------
oil:tallow oil derived acids. A number of distilled tall oil
soaps (tall oil is derived from the waste streams of paper
manufacture) are also made for industrial purposes.
In some cases, the soap making process is operated continuously
in tandem with a fat splitting process. The fatty acids and
caustic solution are proportionated into a reactor continuously
by pumps having a common variable speed drive. The appropriate
amount of salt is also programmed in to maintain the correct
electrolyte content.
The resulting neat soap will have about 30 percent moisture.
To clarify the soap solution, the soap stream coming out of the
reactor is sometimes filtered with clay. The spent clay creates
a certain amount of solid waste and the filter press is washed
out occasionally. Otherwise this is a "clean" process.
The neat soap is further processed into bars or liquid
formulations in the same manner as the product from kettle
boiling.
GLYCERINE RECOVERY (104)
Concentrat ion
The kettle boiling soap process generates an aqueous stream
referred to as sweet water lyes. This stream will contain 8-10
percent glycerine, a heavy salt concentration and some fatty
materials. It is processed by first adding a mineral acid (HCl)
to reduce the alkalinity. This is followed by the addition of
alum which precipitates insoluble aluminum soaps. The
precipitate carries other impurities down with it. If the stream
were not treated with alum, there would be severe foaming in the
evaporators, and the contaminant would be carried forward into
the glycerine. The cleaned up glycerine solution is sent to the
evaporators.
The evaporators (in some smaller plants there will be only one)
are heated under reduced pressure. The partial vacuum is
generated by a barometric condenser. They frequently operate at
0.13 to 0.07 atm (660 mm - 710 mm or 26 - 28" Hg of vacuum).
As the glycerine is concentrated the salt comes out of solution
and is removed from the evaporation kettle, filtered and returned
to the soap making process. In many plants this separating
function is performed continuously with a centrifuge with the
filtrate being returned to the evaporator.
The glycerine is usually concentrated to 80 percent by weight and
then either run to a still to be made into finished glycerine, or
stored and sold to glycerine refiners.
29
-------
uo
o
104 GLYCERINE RECOVERY
1041 RECEIVING
STORAGE-TRANSFER
1042 LYE TREATMENT
1043 GLYCERINE EVAPORATION
1044 GLYCERINE STILL
TREATED
.GLYCERINE
LIQUOR
RECYCLE
STEAM
STEAM
CRUDE
GLYCERINE
SALT RECYCLE
TO SOAP
MANUFACTURE
1 1 1
* 1 *
GLYCERINE
FOOTS
104428
\
I
1
1
SOLID WASTE
104409
BAROMETRIC
CONDENSATE
104418
FIGURE
COOLING TOWER
SLOWDOWN
104404
-------
The sweet water glycerine from fat splitting is flashed to
atmospheric pressure, thereby releasing a considerable amount of
water very quickly. This can provide a glycerine stream of 20
percent glycerine or more going to the evaporators. Since there
is no salt used in fat splitting there will be none in the sweet
water.
The water from the barometric condenser used in concentrating
will be slightly rich in BOD5 due to the carryover of glycerine.
Distillation
The concentrated glycerine (80 percent)is run into a still which,
under reduced pressure, yields a finished product of 98+ percent
purity. Here again a barometric condenser is used to create the
partial vacuum.
At room temperature, the still bottoms (also called glycerine
foots) are a glassy dark brown amorphous solid rather rich in
salt. Water is mixed with the still bottoms and run into the
waste water stream. This particular stream is very rich in BOD5,
and readily biodegradable. Many alternative methods of disposal,
including incineration, have been evaluated, but the general
practice is disposal in a waste water stream.
The other waste water stream, the barometric condenser water,
will also contribute to the total BOD5/COD load from the
glycerine still.
Some glycerine refining is done by passing the dilute stream over
ion exchange resin beds, both cationic and anionic, and then
evaporating it to 98+ percent glycerine content as a bottoms
product. This method is suitable where there are copious
quantities of water available and energy costs are very high.
In the backwash of the ion exchange process the organic suspended
solids are stripped from the system. The regeneration cycle of
both types of beds will add a significant dissolved solids load
to the waste water system.
There are frequently three sets, in series, of both cation and
anion exchange resins used in this process. Each step is
designed to reduce the input load by 90 percent. Seme of the fat
splitting plants are equipped with this type of unit.
SOAP FLAKES AND POWDERS (105)
Neat soap (65 - 70 percent hot soap solution) may or may not be
blended with other products before flaking or powdering. Neat
soap is sometimes filtered to remove gel particles and run into a
crutcher for mixing with builders.
31
-------
105 SOAP FLAKES AND POWDERS
105! RECEIVING
STORAGE-TRANSFER
1052 FLAKING
CRUTCHING-DRYING
1053 SPRAY DRYING
1054 PACKAGING
NEAT SOAPS
BUILDERS
ADDITIVES
-d
-D
FILTER BACKWASH
105129
LEAKS, SPILLS. STORM
RUNOFFS, WASHOUTS.
105202
WASTEWATER
1053O1
GASES
LEAKS, SPILLS, STORM
RUNOFFS, WASHOUTS.
1053O2
SCRUBBER
WASTEWATER
1054O1
PACKAGED
SOAP TO
WAREHOUSE
FIGURE
-------
After thorough mixing, the finished formulation is run into a
flaker. This unit normally consists of a two roll "mill" having
two steel rolls. The small upper one is steam-heated while the
larger lower one is chilled. The soap solidifies on the lower
one and is slit into ribbons as it sheets off the roller.
The ribbons are fed into a continuous oven heated by hot air.
The emerging flakes contain 1 percent moisture. As all of the
evaporated moisture goes to the atmosphere, there is no waste
water effluent.
In spray drying, crutched, heated soap solution is sprayed into a
spray tower, or flash-dried by heating the soap solution under
pressure and releasing the steam in the spray dryer under reduced
pressure. In either case the final soap particle has a high
ratio of surface area to unit of weight, which makes it readily
dissolvable in water.
Some operations will include a scrap soap reboil to recover
reclaimed soap. The soap reboil is salted out for soap recovery
and the salt water is recycled. After frequent recycling the
salt water becomes so contaminated that it must be discharged to
the sewer.
Occasional washdown of the crutcher may be needed. The tower is
usually cleaned down' dry. There is also some gland water which
flows over the pump shaft picking up any minor leaks. This will
contribute a very small, but finite, effluent loading.
BAR SOAP (106)
The procedure for bar soap manufacture will vary significantly
from plant to plant, depending upon the particular clientele
served. The following description typifies bar soap manufacture.
In some processes additives are mixed with the neat soap in a
crutcher before any drying takes place. Another approach is to
begin the drying process with the hot neat soap going to an
"atmospheric" flash dryer followed by a vacuum drying operation
in which the vacuum is drawn by a barometric condenser. Soap is
then double extruded into short ribbons or curls and sent to
plodders for further blending or physical processing. At this
point the soap will normally have 8 - 14 percent moisture
depending upon the previous course of processing.
Next, a milling operation affords the opportunity to blend in
additives as well as modify the physical properties of the soap.
This operation has much more significance than just achieving
uniformity in the mixing of further added ingredients. The
physical chemistry of soap is fairly complex. Unless a bar of
soap is almost predominately left in the Beta phase, as distinct
from the Omega phase, longrange solubility, warping resistance,
and lathering properties are poor. Rapid chilling of the soap
33
-------
U)
jr-
106 BAR SOAPS
1061 RECEIVING
STORAGE-TRANSFER
1062 CRUTCHING AND DRYING
1063 SOAP MILLING
1064 PACKAGING
NEAT SOAP
-HD-
ADDITIVES-»-i \
FILTER
STRAINER
FILTER BACKWASH
1 06129
WATER
TO SOAP
MILLING
WATER
SCRAP TO
-•-SOAP
RECYCLE
FINISHED SOAP
—|-»-8ARS AND CAKES
TO WAREHOUSE
FIGURE 7
-------
puts it predominantly in Omega phase but successive milling steps
bring it back into Beta phase - hence the importance of milling.
The mill consists of two polished rolls rotating at different
speeds to maximize the shearing forces. After milling, the soap
is cut into ribbons and sent to the plodder.
The plodder operates much like a sausage grinder. It thus
extrudes and cuts the soap into small chips, followed by further
mixing in which all of the individual pieces are melted together
into an homogeneous mass. The plodder is often operated under
reduced air pressure so that any occluded air is removed in the
blending process. It has a powerful screw that forces the soap
through minute holes in a perforated plate.
Plodding completed, the soap is extruded continuously in a
cylindrical form, cut to size, molded into the desired form, and
wrapped for shipment. Most of the scrap in this operation is
returned to the plodder.
At times there will be soap scrap which has become too dry to
process properly in the plodder and it must be returned to
earlier steps in the soap making process.
The amount of water used in bar soap manufacture varies greatly.
In many cases the entire bar soap processing operation is done
without generating a single waste water stream. The equipment is
all cleaned dry, without any washups. In other cases, due to
housekeeping requirements associated with the particular bar soap
process, there are one or more waste water streams from air
scrubbers.
Since we are dealing with a consumer product with very distinct
(and important to the consumer) esthetic properties, all of these
processes can claim significance and essential character in the
making of a particular bar.
Occupying a very minor position in the soap market, a bar made
from cold frame soap may be found. After the saponification
reaction, this soap is poured directly from the reactor into
molds. Upon cooling and the completion of saponification, the
molded soap is cut into bars. The en-tire operation is carried
out without the generation of any waste water.
LIQUID SOAP XI071
Neat soap (often the potassium soap of fatty acids) is blended in
a mixing tank with other ingredients such as alcohols or glycols
to produce a finished product, or with pine oil and kerosene for
a product with greater solvency and versatility. The final
blended product may be, and often is, filtered to achieve a
sparkling clarity before being drummed.
35
-------
107 LIQUID SOAP PROCESSING
7077 RECEIVING
STORAGE-TRANSFER
1072 BLENDING
7073 PACKAGING
POTASSIUM SOAPS
ADDITIVES
SOLVENTS
WASH DOWNS;
HEELS. 707272
LEAKS, SPILLS, STORM
RUNOFFS, WASHOUTS.
707702
PACKAGING
EQUIPMENT
LI QUID SOAPS
•TO WAREHOUSE
WASHOUTS
107302
FIGURE 8
-------
In making liquid soap, water is used to wash out the filter press
and other equipment. Waste water effluent is minimal.
DETERGENT PROCESS DESCRIPTIONS
The first modern detergent introduced in the United States in
1933 was an alkyl naphthalene sulfonate. The primary reason for
the success of detergents is their ability to overcome the hard
water behavior of soaps. Even though the detergents also react
with hard water minerals, the resulting compounds are themselves
soluble, or remain colloidally dispersed in the water system.
There are four main groups of detergents:
Anionics
Cationics
Amphoterics
Nonionics
Anionics comprise the most important group of detergents. They
are usually the sodium salts of an organic sulfate or sulfonate.
Sulfates are made from long chain "fatty alcohols" (of animal or
petroleum origin) . Sulfonates generally are made from alkyl aryl
precursors.
By 1957 synthetic detergents took over 70 percent of the market
for soap- like products in the United States.
Cationic detergents are known as "inverted soaps" because
long chain ion is of the opposite charge to that of a tr^c soap
when dispersed in water.
This class of detergents is made in quite small volumes. They
are relatively expensive and somewhat harsh on the skin. They
make excellent bacteriostats and fabric softeners and are used
for this purpose.
Nonionic detergents are an increasingly popular active ingredient
of automatic washing machine formulations. These products are
unaffected by hard water (they do not form ions) and are very low
foamers (minimum foam when agitated) . They are made by the
addition of ethylene oxide to an alcohol.
Amphoterics are those surface active agents which can either be
anionic or cationic, depending upon the pH of the system wherein
they work. An important class chemically, they account for only
a very small portion of the detergent market.
DETERGENT MANUFACTURING PROCESSES
37
-------
A finished, packaged detergent customarily consists of two main
components, the active ingredient (surfactant) and the builder.
The function of the surfactant is essentially that of wetting the
substrate to be cleaned. The builder performs many functions
including buffering the pH, soil dispersion, and soil anti-
redeposition. Both classes of materials are required for proper
detergent performance.
The processes described under this heading include the
manufacture of the surfactant as well as preparation of the
finished detergent. The number following the title of each
process refers to the process flow chart.
OLEUM SULFONATION/SULFATION (201)
One of the most important active ingredients of detergents is the
alcohol sulfate or alkyl benzene sulfonate - and particularly
those products made via the oleum route.
In most cases the sulfonation/sulfation is carried out
continuously in a reactor where the oleum (a solution of sulfur
trioxide in sulfuric acid) is brought into intimate contact with
the hydrocarbon or alcohol. Reaction is rapid. The stream is
then mixed with water and sent to a settler.
Prior to the addition of water the stream is an homogeneous
liquid. With the addition of water, two phases develop and
separate. The dilute sulfuric acid is drawn off and usually
returned to an oleum manufacturer for reprocessing up to the
original strength. The sulfonated/sulfated material is sent on
to be neutralized with caustic.
This process is normally operated continuously and performs
indefinitely without need of periodic clean out. Pump glands
occasionally leak. Anticipating this problem, a stream of water
is normally played over pump shafts to pick up such a leak is it
occurs, as well as to cool the pump. The flow of waste water
from this source is quite modest but continual.
AIR-S03 SULFATION/SULFONATION (202)
This process for surfactant manufacture has numerous unique
advantages and is used extensively. In the oleum sulfation of
alcohols, formation of water stops the reaction short of
completion because it reaches a state of equilibrium, resulting
in low yields.
With SO3 sulfation, no water is generated, hydrolysis cannot
occur and the reaction proceeds in one direction only.
The absence of water in the SO3 reaction is of a lesser
importance in sulfonation. What is particularly troublesome in
the use of oleum for alcohol sulfation is that water cannot be
used for oleum separation due to the potential hydrolysis that
38
-------
201 OLEUM SULFATION AND SULFONATION (BATCH AND CONTINUOUS)
2011 RECEIVING
STORAGE-TRANSFER
2012 SULFONATION
WATER CAUSTIC
2013 SPENT ACID
SEPARATION
A1 KVI RFN7FIMF
I I
OLEUM
FUME
SCRUBBER
1
I
I
1
WASTE-
WATER
201101
T
LEAKS, SPILLS, STORM
RUNOFFS, WASHOUTS.
20/702
T
COOLING -
WATER
-WATER
r
i_*
t t
„ RPAPTOR
*
i
* SCRUBBER
j,
t t
COOLING
WATER
201200
WASTE-
WATER
201201
LEAKS, SPILLS, STORM
- RUNOFFS, WASHOUTS.
20/202
WATER*
MIXER
-
i
1
1
1
1
\
WASHOUTS
201302
SETTLER
t
SPENT ACID
207305
SULFONIC ACID
ANDSULFURIC
ACID ESTER TO
NEUTRALIZATION
FIGURE
-------
202 AIR-SO, SULFATION AND SULFONATION (BATCH AND CONTINUOUS)
2027 RECEIVING
STORAGE-TRANSFER
2022 SULFUR BURNING
2023 SULFONATION-SULFATION
SULFURf
SO3 LIQUID
ALKYL BENZENE
ALCOHOLS
ETHOXYLATES
SULFONIC ACID AND
^SULFURIC ACID ESTER
TO NEUTRALIZATION
AND SALES
LEAKS, SPILLS, STORM
RUNOFFS, WASHOUTS.
202/02
SULFURIC ACID
202309
1
1
1
\
VENTG
2023O8
WASHOUTS
202302
FIGURE 10
-------
would take place. Even if this were not a worry, no phase
separation of the components takes place with the addition of
water to sulfated alcohols in oleum.
SO3. sulfonation/sulfation is also quite amenable to batch
processing and in this manner can produce products having a
minimum of sodium sulfate (all of the excess of SO^r or sulfuric
acid in the case of oleum sulfonation, will be converted into
sodium sulfate in the neutralization step with caustic) . Another
advantage of the SO3_ process is its ability to successively
sulfate and sulfonate an alcohol and a hydro-carbon respectively.
Care must be excercised in the SO3 process to control reaction
conditions - particularly temperature - to minimize char
formation and possible sulfonation of the hydrocarbon chain of
the alcohol.
Because of this reaction's particular tendency to char the
product, the reactor system must be cleaned thoroughly on a
regular basis. In addition there are usually several airborne
sulfonic acid streams which must be scrubbed, with the waste
water going to the sewer during sulfation.
can be generated at the plant by burning sulfur or sulfur
dioxide with air instead of obtaining it as a liquid. See the
accompanying flow sheet for the process. For further technical
information see Section X.
SO3 SOLVENT AND VACUUM SULFONATION ( 203)
Undiluted SO3_ and organic reactant are fed into the vacuum
reactor through a mixing nozzle (vacuum maintained at 0.06 atm
(5" Hg) . Recycle is accomplished by running the flashed product
through a heat exchanger back into the reactor. The main
advantage of the system is that under vacuum the S
-------
ro
203 - SO3 SOLVENT AND VACUUM SULFONATION
2031 RECEIVING
STORAGE - TRANSFER
2Q32 SULFONATION
2033 SULFONATION
ALKYL BENZENE —
AI rOHOL*!
ETHOXYLATES
Qr>
au2 ~
SO3 LIQUID
>
^^
J
'
n
1
\
"A \
VACUUM
REACTOR
STEAMJET e
X
X
X
^
i
s
1
~*
X
->
VAPORIZER
BLOWER I
1
i
/ x^_
X.
1
1
1
^ /J
1 i-
_ STEAM
•»• SULFONIC
ACID
FEED
STOCK
y
j—Z REFRIGERATION
S
>•
'
o
2 -> S02 TO
STORAGE
LIQUID
so2
REACTOR
' 1
| \tf *«y
t
SCRUBBER
T
^ DEGASSER
1
1
1
1
.u
fc'
^_
1
1
L>
LEAKS, SPILLS,
STORM RUNOFFS,
WASHOUTS
203102
WATER
CAUSTIC
SULFONIC
ACID
CONDENSATE
203206
CONDENSATE
203217
WASTEWATER
203301
1
WASHOUTS 203202
WASHOUTS 203302
FIGURE 11
-------
204 SULFAMIC ACID SULFATION
ALCOHOLS-
ETHOXYLATES-
SULFAMIC ACID-
2041 RECEIVING
STORAGE-TRANSFER
2042 SULFATION
LEAKS, SPILLS, STORM
RUNOFFS, WASHOUTS.
204102
SOLVENTS
"WATER
•CAUSTIC
AMMONIUM ALKYL
SULFATES
WASTEWATER
2O4201
WASHOUTS
2O42O2
FIGURE 12
-------
205 CHLOROSULFONIC ACID SULFATION
205? RECEIVING
STORAGE-TRANSFER
2052 SULFATION
CHLOROSULFONIC ACID
ALCOHOLS
ETHOXYLATES
LEAKS, SPILLS, STORM
RUNOFFS, WASHOUTS.
205?02
WATER
CAUSTIC
^ ALKYL SULFURIC ACID ESTER
TO NEUTRALIZATION
FIGURE 13
-------
water of sulfation and generates pratically no side reactions.
It is a corrosive agent and generates HC1 as a by-product.
An excess of about 5 percent chlorosulfonic acid is often used.
It will yield an inorganic salt upon neutralization which is
undesirable in some applications as it can result in salt
precipitation in liquid formulations, etc.
NEUTRALIZATION OF SULFURIC ACID_ESTERS
AND SULFONIC ACIDS "(206)
This step is essential in the manufacture of detergent active
ingredients; it converts the acidic hydrophylic portion of the
molecule to a neutral salt.
Alcohol sulfates are somewhat more difficult to neutralize than
the alkylbenzene sulfonic acids due to the sensitivity to
hydrolysis of the alcohol derivative. For this reason,
neutralization is usually carried out at a pH above 7 and as
rapidly as possible.
This is not a difficult feat for those who neutralize con-
tinuously, but it is more of a problem for the batch processor
unless he has excellent stirring.
As a result of hydrolysis occurring in the neutralization step,
there will be some free alcohol generated which would be picked
up in the oil and grease analysis. As a product this is not all
bad since the free alcohol can actually be considered a foam
stabilizer in some situations. If used in heavy duty products,
the alcohol tends to be lost in the spray tower.
SPEAY DRIED DETERGENTS (207)
This is another critical area of detergent manufacture. In this
segment of processing, the neutralized sulfonates and/or sulfates
are brought to the crutcher where they are blended with requisite
builders and additives. From here the slurry is pumped to the
top of a spray tower of about 4.5 - 6.1 m (15 - 20ft) in diameter
by 45 - 61m (150 - 200 ft) high where nozzles, around the top,
spray out detergent slurry of approximately 70 percent
concentration.
A large volume of hot air enters the bottom of the tower rising
to meet the falling detergent. For low density products, hot gas
and powder flow concurrently downward.
This step is critical in that the detergent particles' shape,
size and density are determined by all of the design preparation
made previously, and the shape and size in turn will largely
determine dusting and the solubility rate of the detergent itself
in the washing process.
45
-------
206 NEUTRALIZATION OF SULFURIC ACID ESTERS AND SULFONIC ACIDS
206; RECEIVING
STORAGE-TRANSFER
206? LIQUID NEUTRALIZATION
2063 DRY NEUTRALIZATION
ACIDS:
SULFURIC ACID ESTERS
SULFONIC ACIDS
BASES
OTHER INGREDIENTS:
WATER; SOLVENTS;
HYDROTROPES.
ADDITIVES
WATER ACIDS -
CAUSTIC
LIQUID PRODUCTS
AND SLURRIES TO
SALE, BLENDING,
OR
CRUTCHING
BASES: x
OTHER
INGREDIENTS: '
*•
»-
it
/
RIBBON
BLENDER
s
H
SCRUBBER
i
\ i
\ 1
1 1
1
1
1
WASTEWATER
206301
1
1
L>
ri
DRY PRODUCTS
TO STORAGE
WATER
WASHOUTS
206302
FIGURE 14
-------
The air coming from the tower will be carrying dust particles
which must be essentially eliminated to meet air quality
standards.
Due to product change and buildup of combustible deposits, the
spray towers are periodically shut down and cleaned. This
practice varies from two or three times a week to once in two
weeks or longer. One thing that all tower operations share is
the cleaning process. First, the easily available material
sticking to the tower walls is scraped to be recycled if at all
possible, or sent to solid waste.
Men are sent into the tower with abrading equipment to continue
the dry cleaning process. Here again, the product is usually
preserved for reuse or disposed of as a solid waste.
Finally, the tower is thoroughly washed down by spraying streams
all over the inside surface. The final step is mandatory since
the detergent manufacturers must be very careful to avoid any
mixing of any phosphate-nonphosphate formulations, white with
colored systems or anionic with nonionic formulations.
The mixing problem is compounded somewhat by the fact that some
detergent manufacturers custom process for a variety of marketers
which requires more frequent spray tower "turnaround".
Waste water streams are rather numerous (see accompanying flow
sheet for process). They include many washouts of equipment from
the crutchers to the spray tower itself. One waste water flow
which has high loadings is that of the air scrubber which cleans
and cools the hot gases exiting from this tower. This is only
one of the several units in series utilized to minimize the
particulate matter being sent into the atmosphere.
All of the plants recycle some of the waste water generated.
Some of the plants recycle all of the flows generated.
Due to increasingly stringent air quality requirements, we can
expect that fewer plants will be able to maintain a complete
recycle system of all water flows in the spray tower area. In
the case of the fast "turnaround11 tower, they, too, are unable to
utilize all of their scrubber and other wash waters.
After the powder comes from the spray tower it is further blended
and then packaged. Solid wastes from this area are usually
recycled.
LIQUID DETERGENTS (208)
Sulfonated and sulfated products, as produced in processes
described in 201 - 206 are pumped into mixing tanks where they
are blended with numerous ingredients, ranging from perfumes to
dyes. From here, the fully formulated liquid detergent is run
down to the filling line.
-------
o>
207SPRAY DRIED DETERGENTS
2071 RECEIVING
STORAGE-TRANSFER
2072 CRUTCHING
2073 SPRAY DRYING
2074 BLENDING AND PACKAGING
ACTIVES:
LAS SLURRY; ALCOHOL
SULFATE SLURRY;
ETHOXYLATES
BUILDERS:
PHOSPHATES: SILICATES:
CARBONATES; SULFATES.
BORATES
ADDITIVES:
AMIDES: SOAPS; FLOOR
ESCENT WHITENESS;
PERFUMES; DYES: PER-
BORATE: CMC: ANTICAKING
AGENTS: ENZYMES
WASHOUTS
207102
FIGURE 15
-------
The filling line usually consists of a long conveyor which passes
many stations. Each station performs a given task, such as
filling, capping, checking weight, labeling, etc. Often, soap
solutions are used to lubricate the conveyor so that the bottles
flow smoothly past the various stations.
Whenever the filling line is to change to a different product,
the filling system must be thoroughly cleaned out. This is
equally true of the mixing equipment. Properties of differing
products are often so contrasting that there must be no cross
contamination; otherwise the performance and other specifications
cannot be met. To avoid this problem the mixing equipment and
all filling plumbing is thoroughly flushed with water until it
runs clear.
PRYa DETERGENT BLENDING J209J
Fully dried "active" (surfactant) materials are blended with
additives, including builders, in dry mixers. In the more
sophisticated plants mixing time is utilized to the maximum by
metering components into weighing bins prior to loading into
mixers. When properly mixed, the homogeneous dry product is
packed for shipment.
Normal operation will see many succeeding batches of detergent
mixed in the same equipment without anything but dry cleaning.
This procedure is followed until the next formulation to be
blended must not be contaminated with even an almost negligible
amount of the previously prepared product. At this time the
equipment must be completely washed down.
For this reason, a modest amount of waste water is required for
the blender to maintain specification requirements.
The products fulfill a wide variety of industrial cleaning uses
from dairy cleaning to box car washing. They are also used to
some extent in household products.
DRUM DRIED DETERGENTS (210)
Drum drying of detergents is an old process. Much of the
equipment still in use is well over thirty years old. The
process yields a fairly friable product which can become quite
dusty with any extensive handling.
There are several types of drum driers; those which have double
rotating heated drums with liquid feed coming onto the space
above and between the rolls, and a twin-drum dryer with dip or
flash feed. The dip feed is a pan in which the "bottom" of the
roll or drum picks up material to be dried.
The thin layer is removed continuously by a knife blade onto
conveyors. The powder is substantially anhydrous. The vapors
-------
208 LIQUID DETERGENT MANUFACTURE
2081 RECEIVING
STORAGE-TRANSFER
2082 BLENDING
2083 PACKAGING
ACTIVES:
LAS; SULFONIC ACID;
ETHER SULFATES;
OLEFIN SULFONATES;
ETHER SULFONATES;
AMINE OXIDES; AMIDES
BUILDERS:
PHOSPHATES; SILICATES
ADDITIVES:
HYDROTROPES;
SOLVENTS; COLOR;
PERFUME
WATER.
BULK
• DETERGENT
SALES
PACKAGING
EQUIPMENT
CASE GOODS
"TO WAREHOUSE
WASHDOWN
208212
HEELS
208213
FIGURE 16
WASHOUTS
2O8202
CONTAINER
WASHINGS
2O8310
SOLID WASTE
2083O9
LEAKS, SPILLS,
WASHOUTS
208302
-------
209 DETERGENT MANUFACTURE BY DRY BLENDING
2097
ACTIVES:
LAS SLURRY; FLAKES;
BEADS; SULFONIC ACID;
AMIDES; ETHOXYLATES
BUILDERS:
SILICATES; CARBONATES;
PHOSPHATES; BORATES
ADDITIVES:
CMC; ANTICAKING AGENTS;
COLORS; PERFUMES;
ABRASIVES; DIATOMACEOUS
EARTH; PUMICE
RECEIVING
STORAGE-TRANSFER
2092 DRY BLENDING
2093 PACKAGING
la.
OUS
X
/
•^^
•*- BULK
DETERGENT
SALES
PACKAGING
EQUIPMENT
CASE GOODS
TO WAREHOUSE
SOLID WASTE
209209
SOLID WASTE
209309
WASHOUTS
209202
WASHOUTS
209302
FIGURE 17
-------
ro
210 DRUM DRIED DETERGENT
2101 RECEIVING
STORAGE-TRANSFER
2102 DRUM DRYING
2103 PACKAGING
BUILDERS
r
SCRUBBER |*-|
CRUTCHER
1
— 1
I
1
1
1
J
» r
i
I
DRUM
DRIER
>
STOR-
AGE
1
1
BULK
DETERGENT
SALES
PACKAGING
EQUIPMENT
PACKAGED
— •- GOODS TO
WAREHOUSE
WASTEWATER
210201
WASHOUTS
210202
WASHOUTS
210302
FIGURE 18
-------
coming off are often collected and removed through a vapor head
between the drums.
The rolls of a drum dryer are often 0.6-1.8m (2 - 6 ft) in
diameter and 0.9 - 4.5 m (3 - 15 ft) long with revolution speeds
of 5 - 10 rpm. About 6-15 seconds residence time is provided
the slurry on hot metal surface which is short enough to avoid
degradation of heat-sensitive products.
As an example of the limitations of drying capacity, the capacity
of the drum varies between 4.5 and 48.8 kg of finished product
per sq meter of drying surface per hour (between 1 and 10 Ib per
sq ft per hour).
This operation should be essentially free of generation of waste
water discharge other than an occasional washdown.
DETERGENT BARS AND CAKES (2111
In answer to the need for a "bar soap" which performs satis-
factorily in hard water, the detergent industry manufactures and
markets detergent bars. They constitute about 20 percent of the
toilet bar market.
There are two types of "detergent" bars; those made of 100
percent synthetic surfactant and those blending synthetic
surfactant with soap. Most products are of the latter type.
Once the active ingredients have been manufactured they are
blended in essentially the same manner and in similar type of
equipment used for conventional soap.
Due to the sensitive nature of the surfactant portion of the
detergent bar, fairly frequent cleanups, including equipment
washdowns, are required. Otherwise thermally degraded surfactant
will contaminate the bar leading to such undesirable properties
as stickiness and off-color.
FORMULATIONS
Soaps, detergents, and cleaning agents - some of the latter
containing specific ingredients for specified cleaning purposes -
contain a wide variety of chemical compounds to carry out the
functions of the cleaning process involved. In the case of soap,
the sodium or potassium salts of a range of fatty acids, having
carbon numbers of 8 to 22, constitute the principal surfactant or
cleansing agent. In addition, there is a certain amount of salt,
NaCl, included in soap to perform the function of having an
electrolyte present, which increases diffusion and surface
orientation, by ion reactions. Glycerine, itself, is often left
in the soap, or purposely added, for its general effect in
promoting a feeling of softness and slipperiness, the latter
53
-------
217 DETERGENT BARS AND CAKES
2111 RECEIVING 2112 MIXING
STORAGE-TRANSFER WORKING-CONDITIONING
2113 STAMPING-PACKAGING
BUILDERS
ADDITIVES
REDIENTS
MIXER
>
— •*•
SCRUBBER
PLODDER
TABLET
MACHINE
I
r
r
Is
/
I
I
<)
r
i
i
- WATER
BAR
CUTTER
PACKAGINC
^
STAMPER
WRAPPER
PACKAGER
WASHOUTS
211202
WASHOUTS
211302
BAR
DETERGENTS
TO
WAREHOUSE
DETERGENT
CAKES
FIGURE 19
-------
feature being one that leads the user to thoroughly wash off soap
residue, especially in personal use.
In the case of a typical all-purpose household detergent, a
general average of approximately ten chemical components are
included in a typical formulation. All these compounds have
definite functions to produce a balanced detergent. The
principal component, of course, is the surfactant itself,
typically an alkyl-aryl sulfonate, a sulfate salt of lauryl
alcohol, and various types of sulfates or sulfonates derived from
ethoxylated alcohol or of other aromatic compound sulfonates.
The surfactant itself is largely effective in reducing
interfacial tension between the surface to be cleansed and the
soil deposit itself. Typically, detergents contain approximately
5-30 percent of such surfactant active-ingredient material.
An important ingredient in detergents, at least up to the
present, is the radical phosphate, PCW, which is included in a
variety of forms, discussed later. The function of the phosphate
is that of a disperser, a suspender, an emulsifier, and a buffer
to reduce the general alkalinity of the surfactants and produce a
detergent in the pH range of 7.0 - 9.0. The phosphate ion has
been an important multiple functioning ingredient in detergents.
If it is reduced by laws, these functions of a detergent will
have to be handled by other compounds that then need to be
included in a formulation. Another major constituent of most
detergents is an inorganic salt. Most typically, these are
either in the form of sodium sulfate and, occasionally, sodium
chloride or other added inorganic salts. In detergents they
serve the purpose of diminishing the interfacial tension, partic-
ularly that between water, carrying the detergent, and the soil
deposition to be removed. They also act for this reason as a
disperser of the soiling. Additionally, an important function is
to provide an electrolyte; i.e., an ion content which enhances
and accelerates the interchange and surface orientation of
wetting and organic solubilizing portions of a molecule. These
inorganics are usually present up to about 20 percent in the
typical formulated detergent.
Methyl cellulose, in amounts of about 1 percent, are present in
many detergent formulations to reduce redeposition of the
soiling, once it has been removed from the soiled surface.
Silica, in various forms, but usually in the form of sodium
silicate, to an extent of 5 percent or less, is included in many
formulations to minimize the corrosion of metals, particularly
those present in a drum liner or other washing container
surfaces. Fatty acids, such as are used in the soap
manufacturing process by neutralization, are added up to a range
of about 3 percent, largely to enhance foam stability and,
therefore, to prevent an over-use of the detergent in the washing
solution. The borates are also generally added, often in the
form of sodium perborate. These borate compounds are added up to
an extent of 10 percent, and serve the purpose of bleaching a
fabric and/or removing stain deposits of soiling on textile
55
-------
surfaces. In addition to these components there are often
perfumes added, as well as anti-oxidants. Dyes are often added
as brighteners, even fluorescent dyes, so that the reflectivity
of the surface is enhanced, making it look brighter. Obviously,
the perfumes are to give a more pleasing odor and aroma. The
anti-oxidants are added, particularly when there are fatty acids
in the composition, to avoid a noticeably rancid odor.
In general, cleaning compounds contain far more of the inorganic
salt compounds, which are more efficacious in cleaning duties
against surfaces such as dishware, flooring, and in the cleaning
of machine parts, after oil has been used during lathing
operations. Thus, a typical floor cleaning formulation contains
as much as 60 percent of sodium silicate, as much as 10 percent
of phosphates, in the form of tri-polyphosphate, also,
occasionally the tetravalent potassium pyro-phosphate. The
surfactant in such cases is usually an alkyl-aryl sulfonate to
make up the balance of the composition. Hand dishwashing
detergents contain active ingredients such as amine oxides and
sulfated ethoxylated lauryl alcohols. The industrial machine
dishwasher products are compounded as high as 50 percent by
weight sodium tri-polyphosphate, another 25 - 50 percent sodium
metasilicate (anhydrous) and a minor amount 2-5 percent organic
surfactant.
Sodium carbonate, present either as the normal divalent
carbonate, or as the sesqui-carbonate, in amounts ranging up to
10 percent, is commonly used. Again, a tri-polyphosphate is
included to the extent of UO percent or up to the balance of the
detergent, if it is a powder.
Of all the functions, mentioned earlier with respect to the
compound, illustrating the functions, the main purpose of a soap,
detergent or cleaning agent must be to loosen occluded soils and
to suspend it so that it does not redeposit. Accordingly, the
basic principle of the surfactant, even as soap itself, is the
lowering of the interfacial tension between the systems
consisting of the fabric or surface to be cleaned and the soiling
on that surface. Frequently the surfactant function is
accomplished by components which also reduce the interfacial
tension between the water in the system, and the air. This leads
to high foaming compositions which are not useful in actually
cleaning and removing the soiling depositions.
In the case of soap, now used mostly for personal body care, the
main function is that of interfacial separation, from the
epithelial or skin surface and the soiling, which can be produced
by the body itself, as well as from extraneous particulate
matter, oils and greases. The main components of the body's own
soiling are those of the fatty acid-esters which range in
composition from carbon numbers C5 up to C37. The compounds of
lower molecular weight are generally the fatty acid salts
themselves or the fatty acid esters of these salts. The other
-------
main soil components ar
-------
-------
SECTION IV
INDUSTRY CATEGORIZATION
Introduction
There are several ways in which the soap and detergent industry
could be categorized. While each may have its own special
rationale, the search was for the system of categorization that
would best identify potential waste water sources and controls,
provide a permit granting authority with a way to analyze a
specific plant regardless of its complexity, and permit
monitoring for compliance without undue complication or expense.
The systems examined included categorization by raw materials
used, wastes discharged, finished products manufactured,
processes employed, and plant size or age.
Systems based solely on raw materials used, wastes discharged, or
finished products manufactured are either overly complex, even if
based on generic chemical groups, or highly arbitrary if greatly
simplified. This is true in respect to both categorization and
monitoring for compliance. Furthermore, they take into
consideration only the potentials for waste generation that are
inherent in the nature of the materials (e.g., boiling point,
solubility, etc.) and ignore the potentials of other factors such
as processes employed.
The operations of the soap and detergent industry may be
considered to consist of application of processes to raw
materials for production of intermediates, which in turn are
subjected to further processing to arrive at the finished or
marketed products. There is an intimate relationship within
chains of raw materials, intermediates, processes and finished
products with the processes employed being the key to obtaining
the finished products from the raw materials. Thus, a system of
categorization based on processes reflects all variables that
affect raw waste discharges.
Plants employing specific sets of processes tend to be of the
same general age and the principal effect of age is reflected in
the processes utilized (e.g., kettle boiling of fats versus
continuous neutralization of fatty acids for production of neat
soap), not in the level of raw waste load generated by a
particular set of processes. Moreover, the determination of age
is complicated by extensive repair and replacement of process
units. For example, what is the age of a large kettle boiling
facility originally constructed 50 years ago, but in which an
average of one kettle has been reconstructed every two years for
the past thirty years? What is the age of a spray drying tower
constructed in 1930 for manufacturing soap granules, modified in
1946 for production of spray dried detergents, and subjected to
periodic replacement of working parts since modification? In
view of the foregoing, age of plants is not considered to be a
practical basis for categorization.
59
-------
Plant size as a basis for categorization is even more complex
than evaluation of age. Some independents have relatively small
plants that in complexity of processes employed equal the largest
plants of the major international companies. A relatively small
operation consisting of a single process chain (e.g., production
of bar soaps utilizing fatty acid neutralization) may equal in
size the comparable segment of the largest complex plant. Size
of plant may be the result of difference in the physical size of
individual units of equipment or the number of units of the same
physical size. Thus, categorization based on size would result
in an unmanageable welter of categories, with many representing
only one or a very few plants.
Though plant size cannot be used as a basis for orderly
categorization, and thus is not reflected in the proposed
guidelines and standards, there are factors generally associated
with size that should be considered. The complexity of a plant
(i.e., number of processes and products) is frequently associated
with size, the small plants tending to be more limited in
diversity. This may curtail the ability of a small plant to work
off a by-product or waste as a feed material for other processes.
Similarly, the limited volume of a waste produced in a small
plant may prohibit installation of by-product utilization
processes (e.g., use of nigre from kettle boiling for manufacture
of pet soaps and soap-based lubricants) on a scale that is
economically viable.
Categorization
The categorization consists of two major categories and 19
subcategories. The major categories follow the natural division
of soap manufacturing (production of alkaline metal salts of
fatty acids derived from natural fats and oils) and detergent
manufacturing (production of sulfated and sulfonated cleaning
agents from manufactured raw materials, primarily petroleum
derivatives). The subcategories are based on discrete
manufacturing units employed by the industry for conversion of
raw materials to intermediated products and conversion of
intermediate products to finished/marketed products. A
manufacturing unit may contain a single process (e.g., continuous
neutralization for production of neat soap by fatty acid
neutralization) or a number of processes (e.g., crutching,
drying, milling, plodding, stamping and packaging for production
of bar soaps from neat soap).
Several advantages result from the categorization. It accounts
for the variable effects on raw waste loads attributable to raw
materials, processes and finished product. The potential sources
and natures of waste waters are readily discernible, as are the
potential in-plant control measures. It is amenable to use in
development of permits irrespective of the complexity of a plant.
The subcategories are as follows:
60
-------
SOAP MANUFACTURE
Soap Manufacture by Batch Kettle (101)*
Fatty Acid Manufacture by Fat Splitting (102)
Soap Manufacture by Fatty Acid Neutralization (103)
Glycerine Concentration (104A)
Glycerine Distillation (104B)
Soap Flakes and Powders (105)
Bar Soaps (106)
Liquid Soap (107)
DETERGENT MANUFACTURE
Oleum Sulfonation and Sulfation (Batch and Continuous) (201)
Air-SO3_ Sulfation and Sulfonation (Batch and Continuous) (202)
SO3 Solvent and Vacuum Sulfonation (203)
Sulfamic Acid Sulfation (204)
Chlorosulfonic Acid Sulfation (205)
Neutralization of Sulfuric Acid Esters and Sulfonic Acids (206)
Spray Dried Detergent (207)
Liquid Detergent Manufacture (208)
Detergent Manufacturing by Dry Blending (209)
Drum Dried Detergents (210)
Detergent Bars and Cakes (211)
*The numbers shown after the subcategories are used
throughout the report to identify the
subcategories/processes.
Three of the subcategories have been further segmented in
recognition of the added waste generation that may result
from specific types of operations. A separate segment has
been established under fatty acid manufacture for the
hydrogenation of the fatty acids to accommodate those
facilities employing hydrogenation. Under spray dried
detergents three segments have been designated; normal
operation, air quality restricted operation and fast
turnaround operation. The latter two produce much more waste
water than the former and thus cannot effect the same degree
of recycle of waste water to process. A separate segment has
been established within the liquid detergent subcategory for
fast turnaround operation involving automated fill lines, a
phenomenon closely associated with the small producer of
liquid household detergents.
6l
-------
-------
SECTION V
WASTE CHARACTERIZATION
INTRODUCTION
Numerous organic and inorganic chemical compounds are used in the
manufacture of soaps and detergents. As the reactions are
carried out some of these materials and their derivatives enter
the waste waters from the processing steps. These materials are
then treated as contaminants and processed as waste water in
conventional waste treatment units. In discussion of the
individual unit processes that follow, the sources and nature of
waste waters are presented in some detail. The numbers associated
with the processes and waste streams are keyed to the process
flow sheets. Figures 1 through 19.
SOAP MANUFACTURE BY BATCH KETTLE — (PROCESS 101)
Introduction
Effluents of this process arise from three sources. Handling of
fats and oils results in leaks and spills (streams 101102 and
101202). These are usually collected with water and the fats
skimmed. Pretreatment of the fats or oils results in process
waste waters 101321 and 101218. Soap making results in two by-
products, 101319 and 101320, which generally are disposed of as
waste waters. These streams are discussed in detail in the
following sections.
Water and Waste Water Balance
Water for this process will usually come from municipal systems
since the plants are old and somewhat isolated. For the
barometric condenser (101218) surface water or cooling tower
water will be used. Since steam is used for heating the fat in
both pretreatment and saponification, some process water is
introduced in this manner.
Kettle boiling soap is a batch process and water use will be
intermittent. Instantaneous flows of 0.12-18.9 I/sec (2-300gpm)
will be experienced. overall water use can be limited to 623
1/kkg (75 gal/1000 Ib) of soap, but as much as 2080 1/kkg (250
gal/1000 Ib) is used.
Water reuse and recycle is not common in kettle boil soap plants
for process water. Where a barometric condenser is used for the
steaming pretreatment step, recycle through a cooling tower is
sometimes used, but even here use of surface water is more
common. Except for the barometric condenser, all water use can
be considered process water.
63
-------
With reasonable water conservation, and excluding barometric
condenser water, total waste water discharge should not exceed
2080-2500 1/kkg (250-300 gal/1000 Ib) for all steps included
within the subcategory. Inclusion of barometric condensers with
recycle through cooling towers and limited blowdown would
approximately double the volume of discharge.
Specific waste water sources and constituents are discussed
generally and specifically tabulated in the next section.
Wa s t e Water constituents
Leaks, spills and storm runoff or floor washing (streams 1C1102
and 101202) are invariably collected for recovery of fats and
oils by settling and skimming in fat traps. The waste water will
contain some emulsified fats, since the skimmers and settlers do
not operate at 100 percent efficiency.
The fat pretreatment is carried out to remove impurities which
would cause color arid odor in the finished soap. Acid and/or
caustic washing may be used. This results in sodium soaps or
sulfuric acid solutions of fatty acids (101231). Other
pretreatment steps make use of proprietary chemical formulas
which result in water containing the treatment chemicals, fatty
impurities and emulsified fats. Clay and carbon treatments give
solid wastes and do not directly result in aqueous effluents, but
steam is used for heating and the condensate must be removed.
Often a barometric condenser is used, and there is carryover of
low molecular weight fatty acids (101218).
Waste waters from the fat skimmer and from the pretreatment steps
each contribute about 1.5 kg of BOD5 per 1000 kg of soap (1.5
lb/1000 Ib) . Concentrations typically are 3600 mg/1 BOD5, 4267
mg/1 COD, 250 mg/1 of oil and grease with a pH of 5.
Saponification of the fats and oils by sodium hydroxide and
salting out of the soaps (graining) with salt does not
necessarily lead to any effluent. The nigre which comes from
washing excess salt and impurities from the neat soap with
aqueous caustic is always recycled to some extent. The organic
portion consists of low grade soap. In some plants, the nigre is
acidified to convert the soaps to fatty acids which are recovered
for sale. Although acidification removes much of the organic
contaminant, some is still discharged (101320). Some manu-
facturers' third alternative for the nigre is the sewer (101319).
The stream referred to as sewer lyes (101319) arises most often
from the reclaiming of scrap soap. The lye and salt water added
to separate the soap must be discarded because it contains paper
and other dirt.
Sewer lyes and nigre are concentrated waste waters (in mg/1)
alkalinity up to 32,000, BOD5 as high as 45,000, COD up to
-------
64,000, chlorides of 47,000 and a pH of 13.5. Volumes, however,
are small - 249 1/kkg of soap (30 gal./1000 Ib).
FATTY ACIDS BY FAT SPLITTING— JPRQCESS 102)
Introduction
In this process, fats and oils are converted to fatty acids and
glycerine by hydrolysis with water. In Section 103 conversion of
fatty acids to soap is considered and Section 104 deals with
glycerine recovery. There are two process condensates which
contain organic contaminants - (102322 and 102418). Also,
treatment of the fatty acid still bottoms results in contaminated
water (1C2423). Since streams from fat pretreatment (102221) and
leaks and spills are essentially the same as analogous streams
(101102 and 101202) in Process 101, the discussion will not be
repeated.
Fatty acids from the fat splitting frequently are given a light
hydrogenation (usually employing a nickel catalyst) to eliminate
polyunsaturation in the acids. The only waste water coming from
this step is that arising from equipment cleanouts.
Water and Waste Water Balance
In general fatty acid plants are relatively new and contain a
water recycle system. The small amount of clean water required
will come from surface water, municipal systems, or wells.
Although operation of surface condensers and barometric
condensers requires thousands of gallons per minute, blowdown
from fatty acid plants ranges from 3.2-12.6 I/sec (50-200gpm).
The other main contaminated stream is from treating still bottoms
(102423). It is smaller, but highly contaminated.
Cleanouts of hydrogenation equipment are infrequent and the total
volume of water is small. Potable water is used to preserve
cleanliness.
With adequate water conservation, including recycle of barometric
Condenser water, total discharge should not exceed 600-700
gal/1000 Ib of anhydrous product in contrast to the present range
of 400-23,000 gal/1000 Ib.
Waste Water ^constituents
See Process Section 101 for discussion of 102102, 102202, and
102402 which are waste waters from leaks, spills and storm
runoff. Also, fat pretreatment wastes 102205 and 102224 are
covered under Process 101 for the analogous streams.
-------
Process condensate 102322 from fat splitting will be contaminated
with volatile low molecular weight fatty acids as well as
entrained fatty acids and glycerine streams. The barometric
condensate 102418 will also contain volatile fatty acids. These
streams will be settled and skimmed to remove the insoluble fatty
acids which are processed for sale. The water will typically
circulate through a cooling tower and be reused. To keep
emulsified and soluble fatty material at a reasonable level, part
of the stream is purged to the sewer. This blowdown (102204,
102304, 102404) contributes about 10 kg of BODS and 18 kg of COD
per kkg (10 Ib BOD5 and 18 Ib COD/1000~lb) of fatty acids
produced plus some oil and grease.
Treatment of stream 102423 consists of acidification to break the
emulsion and skimming of insoluble fatty acid pitch. The waste
water is neutralized and sent to the sewer. This waste water
will contain salt from the neutralization, zinc and alkaline
earth metal salts from the fat splitting catalyst and emulsified
fatty acids and fatty acid polymers. One plant had about 0.6 kg
of BODJ5 and 0.9 kg of COD/kkg (0.6 Ib BOD5 and 0.9 Ib COD/1000
Ib) of fatty acids from this source.
Fatty acids and a modest amount of nickel soaps constitute the
bulk of contaminants from hydrogenation. Very small amounts of
suspended nickel may be present.
SOAP BY FATTY ACID NEUTRALIZATION — (PROCESS 103)
Introduction
This process is relatively simple and high purity raw materials
are converted to soap with essentially no by-products. Leaks,
spills, storm runoff and washouts are absent. There is only one
waste water of consequence. It is 103326, the sewer lyes from
reclaiming of scrap. Stream 103224 is generally nonexistent
since there is a net consumption of brine in the process.
Water and Waste Water Balance
Except for the small amount of water (258 1/kkg; 31 gal/1000 Ib
of soap) used for reclaiming scrap and resulting in the sewer
lyes, the process produces no other aqueous effluent. Potable
water is fed into the process.
Waste Water Constituents
The sewer lyes (103326) will contain the excess caustic soda and
the salt added to grain out the soap. Also, they will contain
some dirt and paper not removed by the strainer. Typically 3 kg
of BOD5 and 5.5 kg of COD/1000 kg (3 Ib of BOD5 and 5.5 Ib of
COD/1000 Ib) of soap will be discharged.
GLYCERINE RECOVERY — (PROCESS 104)
66
-------
introduction
The feedstock for this unit process comes from soap boiling and
fat splitting processes 101 and 102. Both crude glycerines will
contain about 90 percent water, but that from soap kettle boiling
will contain a fair amount of salt and some NaOH. Both streams
will contain soap or fatty acids which must be removed in the
pretreatment section by precipitation with alum and filtration.
There are three waste waters of consequence from this process;
two barometric condensates, from evaporation of water (104318)
and from distillation of glycerine (104418), plus the glycerine
foots or still bottoms (104428). Contaminant of the barometric
condensates is essentially glycerine with a little entrained
salt. The glycerine foots are water soluble and are removed by
dissolving in water.
Glycerine can also be purified by use of ion exchange resins to
remove the sodium chloride followed by evaporation of the water.
This process puts additional salts into the waste water but
results in less organic contamination.
Water, and Waste Water Balance
Compared with the amount of water used in the barometric
condensers, water used for other purposes is negligible.
Installations not recirculating cooling water through a cooling
tower use from 698,000-1,540,000 1 of water per kkg (84,000-
185,000 gal. of water per 1000 Ib) of glycerine produced. With a
cooling tower, blowdown consumes 9975 1/kkg (1200 gal./1000 Ib)
glycerine.
The ion exchange process is reported to use 449 1/kkg (54
gal/1000 Ib) of glycerine for both backwashing and regeneration.
The source of water for glycerine recovery is usually surface
water. Since it is used mainly for condensing steam, quality is
unimportant. Typically, a plant will withdraw water from a
river, put it through the barometric condensers, and discharge it
into the river with no treatment.
As mentioned above, water used for washout of the still, for
steam generation and the ion exchange process is relatively
small, generally less than 200 gal/1000 Ib. These water uses
require treated water, usually from municipal supplies. No water
is produced or consumed in the process. Approximately 60-70
percent of the total water used is associated with the glycerine
concentration operation.
Waste Water Constituents
The two barometric condensers streams (104318 and 104418) become
contaminated with glycerine and salt due to entrainment. stream
67
-------
104428 is a water soluble by-product which is disposed of by
washing into the sewer. It contains glycerine, glycerine
polymers, and salt. The organics will contribute to BOD5, COD
and dissolved solids. The sodium chloride will also contribute
to dissolved solids. Little or no suspended solids, oil and
grease or pH effect should be seen.
From the glycerine evaporator barometric condenser about 30 kg of
COD and 15 kg of BOD5 per kkg (30 Ib of COD and 15 Ib of BOD5 per
1000 Ib) of product will be discharged. The foots and glycerine
still contribute about equal amounts of BOD5 and COD, 2.5 kg (2.5
Ib) and 5 kg (5 Ib) respectively per kkg (1000 Ib) of glycerine
produced. Because the barometric condensers use large amounts of
water, concentrations are low. The foots are diluted only enough
to remove them from the still, and concentrations of organics and
salts are about 30,000-400,000 mg/1.
SOAP FLAKES AND POWDERS — (PROCESS 105)
Introduction
In this process the neat soaps from processes 101 or 103 are
converted to flakes or powders for packaging and sale. The unit
processes produce the dry soap in the physical form desired.
There are a number of possible effluents shown on the flow sheet
for process 105. However, survey of the industry showed that
most operating plants either recycled any waste water to
extinction, or used dry cleanup processes. Occasionally water
will be used for equipment cleanup.
In converting neat soap to flakes, powder or bars, some scrap
results. The flow sheets show scrap reclaim in processes 101 and
103. There is an aqueous effluent - sewer lyes - from this
reclaim operation (streams 101319 and 103326). All existing soap
plants both make and process soap. Therefore, the given
categorization will handle the effluent sewer lyes under process
101 or 103. Should a plant start with neat soap, the sewer lye
guidelines should be applied to 105.
BAR SOAPS —(PROCESS 106)
Introduction^
To produce soap bars, neat soap is dried and physically worked
prior to extrusion and stamping. Some plants have filter
backwash (106129), scrubber waters or condensate from a vacuum
drier (106201) and water from equipment washdown (106202 and
106302).
Waste Water Balance
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Water from drying neat soap is vented to the atmosphere. Water
use by plants producing dry soap varies from none to 6230 1/kkg
(750 gal/1000 Ib) of soap made. The largest quantity is required
when a barometric condenser is used on the drier. In those
operations employing barometric condensers, both volume of
discharge and level of contamination can be reduced materially by
installation of an atmospheric flash evaporator ahead of the
vacuum drier.
Waste Water constituents
The contaminant of all waste waters is soap which will contribute
primarily to BOD5 and COD. Concentrations of BOD5 and COD are
typically 1600 mg/1 and 2850 mg/1 respectively in the scrubber
(106201)i which is the major source of contamination. Driers
contribute from 0.3 - 0.7 kg/kkg (0.3 - 0.7 lb/1000 Ib) of soap
to waste waters. Washouts of the filter and of equipment account
for the remainder to give an average process total of 2 kg of
BOD.5. per kkg (2 lb/1000 Ib) of dry soap.
LIQUID SOAPS — (PROCESS 107)
Introduction
Production of liquid soaps consists of a simple blending
operation followed by filling of rather large containers (drums)
for sale. According to manufacturers interviewed, there is very
little aqueous effluent. Leaks and spills can be recycled or
handled dry. Washout between batches is usually unnecessary or
can be recycled to extinction.
Water Balance
Some water is used as a part of the liquid soap formula, and
small amounts (16.6 1/kkg of dry soap or 2 gal /1000 Ib) are
occasionally used for cleanup.
Waste Water Constituents
The liquid soaps will contribute to BOD5, COD, and dissolved
solids. However, amounts are very small (0.1 kg BOD.5 and 0.3 kg
COD/k kg of product) (0.1 Ib BOD5 and 0.3 Ib COD /1000 Ib) .
OLEUM SULFONATION AND SULFATION — (PROCESS 201)
Introduction
The principle raw materials for synthetic detergent manufacture
are alkylbenzenes, fatty alcohols and alcohol ethoxylates. These
are converted to surface active agents by sulfonation or
sulfation and neutralization with sodium hydroxide or other
bases. There are no process waste waters from the oleum
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sulfonation and sulfa-tion reaction, leaks, spills and washouts
result in some highly acidic wastes (streams 201102, 2C1202 and
201302). The oleum tank breathing scrubber which collects SO3
vapors during filling of the tank also contributes sulfuric acid
to the waste waters (201101). Although cooling water is used for
the sulfonation, it is indirectly used to cool Freon or brine
systems and doesn't become contaminated.
Although the amount of acids released are small, both the
sulfuric and sulfonic acids are strong acids and small amounts
can give a pH of 1 - 2; therefore, neutralization of spills is
imperative. Also, the sulfonic and sulfuric acid esters are
surface active (MBAS) and contribute to BOD^ and COD. Some oil
and grease can be expected from spills of organic raw materials.
The pH will be very low.
Water and Waste Water Balance
Usually leaks from pump packing glands will be flushed away
continuously with small streams of water. Little water is used.
Because the water use is small, 100 - 2740 1/kkg (12-330 gal/1000
Ib) of surfactant, potable water is generally used, since the
oleum tank scrubber will only be used when the tank is being
filled, little water is used here.
Since sulfonation is highly exothermic and temperatures must be
kept low to avoid charring, the cooling water for sulfonation is
a large stream. Well water or municipal water is preferred
because of their low temperatures making the refrigeration cycle
more economical. In the more efficient operations the cooling
water is recycled through a cooling tower and the discharge is
limited to blowdown.
Haste Water Constituents
Since the source of contaminants is leaks and spills, all the raw
materials and products may be present. These are fatty alcohols,
dodecylbenzene, sulfuric acid, dodecylbenzene sulfonic acid, and
the esters of sulfuric acid and alchohols. These chemicals will
contribute acidity, sulfate ion, MBAS, oil, BOD5 and COD to the
waste water stream.
Concentrations of contaminants will depend on the amount of water
used for washdown. Amounts of contaminants average 0.2kg (0.2
Ib) BOD5, 0.6 kg (0.6 Ib) COD and 0.3 kg (0.3 Ib) MBAS per 1000
kkg (1000 Ib) of sulfonated product. The pH will usually be very
low (1-2) unless the sulfonation wastes are commingled with
neutralization wastes.
AIR-S03 SULFONATION & SULFATION (PROCESS 202)
Introduction
TO
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Anhydrous SO3_ is used to sulfonate aklylbenzenes and to sulfate
alcohols and alcohol ethoxylates converting them to surface
active agents. The acids produced are neutralized with NaOH,
ammonia and other bases as described in process 206.
Because of the hazardous nature of anhydrous SO3, the systems
designed for its use are essentially leak-free. However, any
leaks and spills will end up in the waste waters. The main
source of contaminated waste waters are by-products. The
incoming air-SO3_ stream will be scrubbed with H2S04 and the spent
acid purged (202309). The effluent gas contains entrained
sulfonic acid, sulfuric acid and SO2 (202301).
Another sizable source (202302) of contamination comes from
startup and shutdown. Plants that run 7 days per week, 24 hours
per day will obviously have much less contamination from this
source than plants that shut down more frequently.
Water Balance
A considerable amount of water is used for cooling the
sulfonation reactor. This is usually a clean water stream.
Approximately 249 1/kkg (30 gal/1000 Ib) of water is used for
disposing of by-products in continuous processes. Water use in
batch operations will be several times as great for washing
reactors and filters. All of this water usually goes to the
sewer.
Waste Water Constituents
Stream 202303 which receives startup slop will contain unreacted
alcohols, alcohol ethoxylates, and alkylbenzenes. These will
show up as oil and grease as well as BOD5 and COD. The other
contaminated streams (202102, 202202, 202309~~and 202301) as well
as 202303 will contain sulfonic and sulfuric acids. These
materials affect MBAS, acidity, SO.U, dissolved solids, BOD5 and
COD.
Concentrations from the process were observed to range from 380-
520 mg/1 of BOD5 and 920-1589 mg/1 of COD. The pH ranged from 2
- 7. Source of the contamination comes from three streams; leaks
and spills - 15 percent, scrubbers - 50 percent and startup slop
- 35 percent.
S03 SOLVENT AND VACUUM SULFONATION — (PROCESS 203)
Introduction
Compared to the Air-SO3_ process, these techniques are used
infrequently. Usually they will be batch operations and
relatively small. Leaks, spills and washouts will be the main
source of contamination. No data specific to these processes was
obtained or submitted, but it is believed that effluents and
71
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contaminants will be essentially the same as for Air-SO3
sulfonation. Process 202.
Waste Water Balance
No direct process water will be used, but a small stream will be
used for cleanup of leaks and spills. Cooling water will be
indirect. It is possible that operators will use barometric
condensers to maintain the vacuum and to strip solvent, which is
usually SO2.. If barometrics are used, there could be a large
volume effluent with low concentrations of MBAS, oil and sulfite.
Waste Water Constituents
Leaks and spills will consist of raw materials and products.
These will include alkylbenzenes, alcohols and ethoxylated
alcohols; sulfonic acids and sulfuric acid esters. These
constituents will contribute BOD5, COD, acidity, dissolved
solids, sulfate, sulfite oil, and MBAS to effluent waste waters.
SULFAMIC ACID SULFATION — (PROCESS 20
-------
washout will be the main source of organic contaminants. Since
HCl is a by-product it may be absorbed in water or caustic and
sent to the sewer.
Water and Waste Water Balance
The only process water used is for absorbing HCl. Cooling water
is non-contact and should remain uncontaminated.
Contaminants found in leaks and spills will be the alcohols or
alkylphenol and alcohol ethoxylates used for feedstocks. Also,
chlorosulfonic acid hydrolysis products (HCl and H21SOU) can be
expected, plus the sulfated surfactants. The same materials will
be in the other waste waters.
Since it is not necessary to clean out the reactor between
batches, raw waste loads will be similar to other sulfonation
processes; i.e., S03-Air. An average of 3 kg (3 Ib) of BOD5 and
9 kg (9 Ib) of COD per kkg (1000 Ib) of sulfated product" was
found. Sizable amounts of acidity and chloride (5 kg/kkg) (5
lb/1000 Ib) can also be expected if the HCl is sent to the sewer,
but many plants recover it and sell it as muriatic acid.
NEUTRALIZATION OF SULFURIC ACID ESTERS & SULFONIC ACIDS —
(PROCESS 2J361
Introduction
This process is used to convert the sulfated and sulfonated
alkylbenzenes and alcohols to neutral salts. Various bases are
used depending on the required characteristics of the final
surface active agent. The dry neutralization process (2063) is
infrequently used in the United States to make consumer products
falling within SIC 2841. However, some industrial products will
be made in this manner. Most salts are made by liquid
neutralization (2062). Plants making neutralized products range
from a small batch kettle of a few thousand kilograms capacity to
several million kilograms per day continuous process units.
Water and Waste Water Balance
Waste waters from these plants come almost entirely from leaks
and spills, with washouts occasionally contributing (206102 and
206202). Indirect cooling water is used since the neutralization
is exothermic, but contamination should be very rare. No process
water is involved.
Waste Water Constituents
All of the anionic surface active agents used in soaps and
detergents will be found in these waste waters. Also the
inorganic salts, such as sodium sulfate, from neutralization of
excess sulfuric acids will be found. Alkylbenzene sulfonates,
ether sulfates, alcohol sulfates, olefin sulfonates, with the
73
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ammonium, potassium, sodium, magnesium and triethanol ammonium
cations will be represented.
These constituents will contribute to BOD5 and COD, MBAS
dissolved solids, Kjeldahl ammonium nitrogen, sulfate, acidity
and alkalinity.
The total amount of contaminants contributed from this process is
quite small. The equipment used has stood the tests of time. Of
course there will always be occasional leaks and spills.
Whether a plant recycles or discharges to a sewer determines the
concentration of contaminants and water usage. When recycle is
practiced, as little as 10.4 1/kkg (1.25 gal./1000 Ib) of water
is used. Concentrations in this case were high - 6000 mg/1 of
BOD5 and 21,000 mg/1 of COD. The other extreme was 4170 1 (1100
galT) of water - a BODj> of 85 mg/1 and a COD of 245 mg/1.
Because of the variety of products made we observed quite a range
of waste loadings: BODS - 0.07 kg -0.8 kg/kkg (0.07 Ib -
0.81b/1000 Ib) of product,~COD - 0.2 kg - 2.3 kg (0.2 Ib - 2.3
Ib) ,. MBAS - 0.1 kg - 3.1 kg (0.1 Ib - 3.1 Ib) .
SPEAY DRIED DETERGENTS —(PROCESS 207)
introduction
This is probably the single largest volume unit process utilized
by the soap and detergent industry. There is great variation in
the operation of spray towers insofar as water use and reuse is
concerned. These variations result from different processing
characteristics of product formulas, influences of air quality
problems, standards and frequency of product changeovers, and
plant integration.
The principal sources of contaminated water are washdown of the
tower - 207312; scrubber waters - 207301 and 207330; and leaks
and spills - 207202 and 207302.
Water and Waste Water Balance
No cooling water is used in this process. All process water
which is added to the crutcher leaves the process as water vapor
from the spray tower (207308), Therefore, all water used is for
various types of cleanup. Some plants employ total recycle of
cleanup water and therefore have a very low rate of discharge.
Some plants discharge all waste waters to the municipal sewer.
Most plants are intermediate and specific problems must be
recognized to be able to understand water disposal practices.
To be able to maintain desirable air quality it may be necessary
to use very large quantities of water for scrubbing organics from
spray tower vent gases. This problem is still under study.
Frequent product changeovers for smaller plants make it
economically and physically impossible to collect and recycle all
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tower washouts. Highly integrated plants have more opportunities
to recycle or use detergent-laden waste waters.
Typical water usage associated with spray tower operations
include: wet scrubbing of air emissions, 30-200 gal/1000 Ib;
equipment washouts (crutchers, spray towers, packaging, etc.), 5-
55 gal/1000 Ib; and clean-up of leaks and spills, 2-20 gal/1000
Ib. Total waste water discharges encountered ranged from less
than 5 gal/1000 Ib to as much as 250 gal/100 Ib.
Waste Water Constituents
All of the streams will be contaminated with the detergent being
produced in the plant at the time. The various surfactants,
builders and additives are listed on the flow diagram entering
2071 Receiving Storage And Transfer.
These constituents will contribute to BODj>, COD, MBAS, dissolved'
and suspended solids, oil and grease and alkalinity.
Average raw waste loads for the three types of operation of spray
towers are tabulated as follows (kg/kkg dry detergent) (lb/1000
Ib) :
BOD5 COD Suspended Oil and
Solids Surfactants Grease
Few turnarounds &
no air quality
problem 0.1 0.3 0.1 0.2 nil
Air quality
problems 0.8 2.5 1.0 1.5 0.3
Fast turn-
around 0.2 0.4 0.2 0.4 0.03
LIQUID DETERGEtjT MANUFACTURE__-- (PROCESS 208)
Introduction
Manufacture of liquid light-duty hand dishwashing and heavy-duty
laundry detergents requires relatively simple equipment for
blending the various ingredients. Usually this is done batchwise
with the several surfactants being added by weight, and then
thoroughly blended.
Filling of the bottles is done on sophisticated high speed
filling lines. This is a most critical and difficult operation
because of machine complexity, speed, and cost.
From the filling line, leaks, spills and overflows are sources of
water contamination (208302). From both the blending and filling
operations, purging the lines between products produce slugs of
75
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detergent, contaminated water (208212, 208213 and 208302). Also,
filled detergent bottles are sometimes washed (208310).
Contaminants from light-duty liquid detergents are very high in
surface active agents. Heavy-duty liquid detergents, produced in
much lower volume, can result in some contamination with builders
(phosphates, carbonates).
Water and Waste Water Balance
Liquid detergents consume water as the major solvent for the
product. Little or no water is used for heating and cooling, but
large amounts of water are used for washing equipment and
packages. Because very small amounts of liquid detergents can
cause extraordinary amounts of foam, it is necessary to use very
large volumes of water; and recycle or reuse of water becomes
impracticable. Reported water usage was in the range of 625-6250
1/kkg (75-750 gal/1000 Ib) of detergent.
Waste Water Constituents
All of the effluent streams will contain the starting ingredients
of the products. These are mainly:
ammonium, potassium S sodium alkylbenzene sulfonates (LAS)
ammonium, potassium & sodium alcohol ethoxy sulfates (ASS)
ammonium, potassium & sodium alkylphenol ethoxy sulfates
ammonium, potassium & sodium olefin sulfonates (OS)
ammonium, potassium & sodium toluene and xylene sulfonates
(hydrotropes)
ammonium, potassium & sodium alcohol sulfates
Fatty acid alkanol amine condensates (amides)
Urea .(hydrotrope)
Ethanol (hydrotrope)
Polyacrylates and polystyrene (opacifiers)
Dyes & perfume
Phosphate & citrate builders
Silicate builders
These constituents will contribute to alkalinity, BOD5, COD,
nitrogen, MBAS (and undetected surfactants) and dissolved solids.
76
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Raw waste loadings vary more in concentration than total amount
between plants. The following were observed:
kg/kkq of detergent rnq/1
BOD5 0.5-1.8 65 - 3UOO
COD 1.0 - 3.1 120 - 7000
MBAS 0.4 - 1.1 60 - 2000
As much as 90 percent of the detergent can come from washout of
tanks and lines when changing products. With fewer changes waste
loads will decrease, but the lower levels in the above table
represent minimum with current practice.
DETERGENT MANUFACTURING BY DRY BLENDING — (PROCESS 209)
Introduction
Production of detergents by this process requires no water for
processing and can be operated without using water for washdown.
Dry builders and surfactants are simply mixed, or liquid
surfactants are sprayed into dry powders so that the entire mass
stays free flowing. Some water may also be sprayed onto the dry
powders to produce more stable hydrates.
DRUM DRIED DETERGENTS — (PROCESS 210)
Introduction
In this detergent drying process, the aqueous slurry of detergent
is dried on steam heated rolls and recovered as flakes. Little
or no formulated household detergent is now made by this process.
Most of the products are high active LAS products for dry
blending of industrial detergent products.
Water and Waste Water Balance
The detergent slurry contains water added in the neutralization
process No. 206. This water is removed as steam and vented to
the atmosphere or scrubbed (201201). Steam condensate is
generated also, but this should be free of contamination
(210203).
Waste Water Constituents
The only appreciable effluent will be similar to, but lower in
concentration than the scrubber water from spray drying (207301) .
Surfactants, builders, and free oils can be expected. These will
contribute to BOD.5, COD, alkalinity, MBAS, dissolved solids and
oil and grease.
DETERGENT BARS AND CAKES — (PROCESS 211)
77
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This process is similar in operation to Process 106 Bar soaps.
The significant difference arises in the more frequent washouts
required because of the heat sensitivity of the detergent active
ingredient. Wash waters will be similar in character to those of
spray dried detergents.
In some instances soap will also be found in the waste water
since it is a part of the blend comprising some toilet bar soaps.
78
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SECTION VI
POLLUTANT PARAMETERS
This section contains a discussion of the specific contaminants
which were selected for guidelines recommendations, and those
which were omitted. Rationales for the decisions are given for
each pollution parameter.
Production of soaps and detergents results in numerous waste
water streams and several types of contaminants which are of
special concern. Synthetic surface active agents not only create
a BOD5 and COD, but also cause water to foam and in high
concentrations can be toxic to fish and other organisms.
Nutrients, particularly phosphate, are of concern because of
their contribution to eutrophication of lakes. Soap production
leads to waste waters with high alkalinity, high salt, and high
oxygen demand. Spills of raw materials contribute to oil and
grease levels. Most of the suspended solids come from organics;
i.e., calcium soaps, and many are of the volatile rather than
non-volatile type. Since strong acids and strong alkalies are
used, pH can be very high or very low in waste waters.
CONTROL PARAMETER RECOMMENDATIONS
To monitor the quality of the treated waste water flows coming
from soap and detergent plants as point source discharges, the
key parameters recommended for sampling and analysis and
structure of guidelines are:
Biochemical Oxygen Demand
All of the organic active materials found in soap and detergent
formulations are biodegradable in varying degrees. Most are
totally and rapidly assimilated, and thus may adversely affect
the oxygen balance of receiving waters. Although highly
criticized for its lack of reliability, the analytical method for
BOD5 is still the only generally accepted method for grossly
measuring the potential impact on the environment.
Unfortunately, not all of the organic materials found in these
waste water flows contribute to the oxygen demand at the same
rate. Some may inhibit the microorganisms which degrade these
contaminants, and others are incorporated into the cell tissue of
the microorganisms at different rates. This leads to varying ra-
tios of BOD5 values when compared to the companion COD test.
There are a number of factors which tend to reduce reliability of
the BOD5 in actual practice. One difficulty stems from the
frequent need for long term acclimation of the biota to the
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special unique organic substrates encountered in the waste
streams from the manufacture of detergents. Too often biota are
employed in the BOD5 tests which are totally unacclimated, or at
best only partially acclimated. When data derived from such
testing are viewed in isolation they tend to indicate that a
large quantity of such organics are resistant to biodegradation
or are only slowly degraded. However, detailed studies carried
out with thoroughly acclimated microbial systems do not support
this casual observation. In fact, the vast bulk of the materials
now employed as synthetic detergents are subject to rapid and
complete assimilation by acclimated saprophytic microorganisms.
Industrial surfactants production does lead to a higher
refractory component than the household surfactants.
The use of the BOD5 test is recommended. However, it is es-*
sential that acclimated biota be maintained, especially where the
concerned effluent originates from a plant producing industrial
cleaners.
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 (DO) 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 DO concentrations that make them less competitive and
able to sustain their species within the aquatic environment.
For example, reduced DO 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 reduced maximum sustained
swimming speed. Fish food organisms are likewise affected
adversely in conditions with suppressed DO. 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
80
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algae blooms due to the uptake of degraded materials that form
the foodstuffs of the algal populations.
Chemical Oxygen Demand
Chemical oxygen demand (COD) is another measure of oxygen
consuming pollutants in water. COD differs from BOD, however, in
that COD is a measure of the total oxidizable carbon in the waste
and relates to the chemically-bound sources of oxygen in the
water (i.e., nitrate which is chemically expressed as NO3.) as
opposed to the dissolved oxygen. Materials exerting COD are not
readily biodegraded (as is the case, for example, with the
complex chemicals, i.e., long chain fatty acids, from soap and
detergent manufacturing) and as a result chemical balances in
streams are altered. Since COD is usually encountered coincident
with BOD, the combined effect is highly deleterious. Because of
the difficulty discussed in the preceding section concerning the
reliability of BOD5, it is recommended that the COD be used as a
primary parameter for characterizing effluents from this
industry. Special attention must be given to insure the complete
oxidation of these materials.
Total Suspended JSolids
Although the waste water sources of the soap and detergent
industry are not notably heavy in suspended solids, suspended
solids should be monitored to insure that stream clarity is not
unduly affected or sludge deposits formed on the stream bed,
particularly by some upset in the processing train.
Suspended solids include both organic and inorganic materials.
The inorganic components include sand, silt, and clay. The
organic fraction includes 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 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.
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
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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.
Surfactants (MBAS)
Because of their possible contribution to foaming in streams and
biological upset through surface effects or toxicity, measurement
and control of the organic active ingredient in effluents is
necessary. Not all organic active materials are measured by the
MBAS procedure, soaps are not detected, nor are non-ionics.
However, both of the latter are measured by the EOD5 and COD
methods.
Oil and Grease
These materials which contribute to visual and olfactory esthetic
problems, exert oxygen demand, and interfere with normal oxygen
transfer from air to water need to be controlled. The analytical
method picks up not only the fatty oils and grease used in the
soap making process, but any hydrocarbon bodies which are
generated from the synthetic detergent portion of the plant
processes. The test method does not distinguish between the two
sources, therefore, the results must be interpreted with
discretion.
Oil and grease exhibit an oxygen demand. Oil emulsions may
adhere to the gills of fish or coat and destroy algae or other
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plankton. Deposition of oil in the bottom sediments can serve to
exhibit 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 a water can 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.
pH, Acidity and Alkalinity
This is a pollutant characteristic important for control since
there are occasional upsets in those portions of the processes
which could potentially lead to highly acidic or alkaline spills
and upset the normal regimen of the receiving waters.
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, 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
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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.
Parameters Omitted
Among the parameters omitted is dissolved solids. While there
will be times of high concentrations of salts in some of the
waste water flows within the plant, by the time they are
commingled with the total plant effluent they will be quite
dilute. In addition, the salts themselves are not in a toxicity
range of concern. If the contamination of the waters by
dissolved solids could be damaging, the permit granting authority
should then issue specific guidelines covering that particular
situation.
Nitrogen
Nitrogen, although important in the general concern in regard to
the quality of the receiving waters, is omitted since there is at
this time very little use of products derived from nitrogen.
Spot checks of industrial effluents and contractor's analysis of
Corps of Engineers permit applications confirmed this
observation.
Phosphorus and,Boron
Phosphate and boron levels found in the raw wastes and treated
effluents from plants manufacturing soaps and detergents are
comparable to those encountered in the influents and effluents of
well operated municipal treatment plants. Moreover, measures to
control the selected parameters will effectively control
phosphate and boron levels. While the importance of phosphorus
as a nutrient (and a potential cause on nuisance aquatic growths)
is well recognized, it is questionable that complete elimination
of all phosphates from point source discharges in this industry
would have a detectable affect on phosphorus levels in any but
the most exceptional receiving waters.
During the past 30 years, a formidable case has developed for the
belief that increasing standing crops of aquatic plant growths,
which often interfere with water uses and are nuisances to man,
frequently are caused by increasing supplies of phosphorus. Such
phenomena are associated with a condition of accelerated
eutrophication or aging of waters. It is generally recognized
that phosphorus is not the sole cause of eutrophication, but
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there is evidence to substantiate that it is frequently the key
element in all of the elements required by fresh water plants and
is generally present in the least amount relative to need.
Therefore, an increase in phosphorus allows use of other, already
present, nutrients for plant growths. Phosphorus is usually
described, for this reasons, as a "limiting factor."
When a plant population is stimulated in production and attains a
nuisance status, a large number of associated liabilities are
immediately apparent. Dense populations of pond weeds make
swimming dangerous. Boating and water skiing and sometimes
fishing may be eliminated because of the mass of vegetation that
serves as an physical impediment to such activities. Plant
populations have been associated with stunted fish populations
and with poor fishing. Plant nuisances emit vile stenches,
impart tastes and odors to water supplies, reduce the efficiency
of industrial and municipal water treatment, impair aesthetic
beauty, reduce or restrict resort trade, lower waterfront
property values, cause skin rashes to man during water contact,
and serve as a desired substrate and breeding ground for flies.
Phosphorus in the elemental form is particularly toxic, and
subject to bioaccumulation in much the same way as mercury.
Colloidal elemental phosphorus will poison marine fish (causing
skin tissue breakdown and discoloration). Also, phosphorus is
capable of being concentrated and will accumulate in organs and
soft tissues. Experiments have shown that marine fish will
concentrate phosphorus from water containing as little as 1 ug/1.
Scope of Parameter Measurements - By Processes
Each of the individual processes of the soap and detergent
industry are reviewed in the following paragraphs in order to
relate the significance of the parameters chosen for guidelines
to the measurement of the contaminants contained in waste water
flows originating in each unit process.
The ways in which effluent discharge can be monitored are
suggested.
SOAP MANUFACTURE BY BATCH KETTLE M 01)
' ' r T ~~ x - \ "
Significant contaminants from this process are the fats and oils
used as raw material; unrecovered sodium chloride, sodium sulfate
and sodium hydroxide; soaps that are spilled or lost and dark
colored by-product soaps. Limits are proposed for BODf> and COD,
suspended solids, oil and grease and a range of 6 - 9 for pH.
The soaps, fats and oils will be controlled by the first four
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tests. A pH in the 6-9 range will insure against discharge of
sodium hydroxide or strong acids.
Since soap plant wastes can cause depletion of dissolved oxygen,
limitation is necessary. Oils and suspended solids cause esthetic
problems. A very high or very low pH is detrimental to almost
all organisms.
No recommendation has been made for specific limitations of the
two inorganic salts, NaCl and Na.2SO.jl. These are relatively non-
toxic (Nad 10,000-20,000 mg/1 MLD;Na SO. 11,000-17,600 mg/1
MLD) , and most receiving waters are below the limits of dissolved
salts set by the United States Public Health Service.
FATTY ACIDS BY FAT SPLITTING (102)
The organic compounds from this process are primarily fatty acids
although some unreacted fat and glycerine from spills and leaks
will also be found. The total of the inorganics will be low
compared to the organics. Sodium hydroxide and sodium sulfate
from fat pretreatment and from treatment of still bottoms are
expected.
Total organics should be controlled by setting BOD5 and COD
limits. Free fatty acids and fats should be controlled by
setting oil and grease and suspended solids limits. The pH
should be controlled.
Contaminants not limited are the generally innocuous sodium
sulfate plus small amounts of zinc and alkaline earth metals used
as the fat splitting catalyst and nickel used as a hydrogenation
catalyst. These metals ions are below harmful concentration in
commingled plant wastes and are further reduced in biological
treatment processes which must be used on the organic
contaminants.
SOAP BY FATTY ACID NEUTRALIZATION (103)
Except for fats and oils the contaminants from this process will
be the same as from the kettle boil soap process. Concentrations
and loadings are much lower, however.
Control of discharge is established by setting limits on BOD5,
COD, pH, suspended solids and oil and grease.
The small amount of sodium chloride relative to the production of
soap should not require regulation unless the receiving stream is
at a critical chloride level.
GLYCERINE RECOVERY (101\
Contaminants in waste waters from this process are water soluble
organics and two inorganic salts. The organics are glycerine and
glycerine polymers. The salts are NaCl and
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Organics discharge is controlled by setting BODfj and COD limits.
Although pollutants affecting pH, suspended solids, and oil and
grease are minimal, limits have been set to guard against carry
over from previous processing steps.
Sodium chloride and sodium sulfate should not be restricted
unless the receiving stream is close to the specified limit for
chloride and sulfate ions.
SOAP FLAKES AND POWDERS (105)
Effluents from this process are minimal. Since almost pure soap
is processed, the contaminants will be primarily soap with only
small amounts of free fatty matter, alkali and salt.
BOD5 and COD are used to limit discharge of soaps, and pH is to
be kept to the 6-9 range. Suspended solids and oil and grease
should be measured to guard against unusual contamination.
Although sodium chloride is not limited, its concentration should
be negligible.
BAR SOAPS (106)
As with soap flakes and powders, waste water contaminants from
this process will be mainly soap. Small amounts of salt and
alkali which are in the soap will also be found. Some free fatty
matter and additives can be expected in the waste waters.
Assignment of BOD5 and COD limits will control the discharge of
soap. Specifying limits for pH, oil and grease, and suspended
solids will handle unusual spills.
Inorganic contaminants should be low and control should be
unnecessary.
LIQUID SOAP (107)
Liquid soaps are formulated products and will contain solvents,
builders, dyes and perfumes in addition to potassium soaps.
Almost all contamination will come from spills so the waste water
will be contaminated with all constituents of the formula.
BODS and COD limits will control overall discharge of organics.
Control of pH to the 6.0 - 9.0 level should present no problem
since the product will be in that range. The suspended solids
and oil and grease tests will be more important here than with
other soaps since the formulated soaps often contain hydrocarbon
solvents.
Inorganic salts should be negligible from this process and thus
require no control. Potassium ion will be found here but the
level should be low enough to require no limitations.
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OLEUM SULFONATION AND SITUATION (201]|
In effluents from this process, one can expect to find the oily
raw materials, sulfuric acid and surfactant sulfonic acids. All
of these contaminants need to be treated before discharge.
Raw material spills should be limited by setting specifications
for the oil and grease and suspended solids. The MBAS test can
measure surface active sulfuric acid esters and be used to limit
their concentration. Total organic contamination can be
monitored and controlled by running the oxygen demand procedures,
BOD5 and COD. Sulfuric acid and sulfonic acids are very strong
acids and must be neutralized before discharge. This can be
assured by specifying a pH of 6 - 9.
The only contaminant not limited is sulfate. Most streams can
absorb current quantities of this ion, but if necessary the
regional permit officer can restrict discharge of sulfate.
AIR SO3 SULFATION - SULFONATION (202][
This process is identical to process 201 with respect to con-
taminant composition. However, the levels of contamination are
higher.
Limitations have been set for BOD5, COD, pH. oil and grease, MBAS
and suspended solids. Sulfate need not be limited for the usual
receiving water.
see the discussion under Process 201 for the rationale.
VACUUM AND SOLVENT SULFONATION (203)
This process is identical to process 201 insofar as contamination
is concerned. One exception is the possible presence of sulfate
in the waste water. Levels should be similar to process 201.
Limits have been set for BODfi, COD, pH, oil and grease and sus-
pended solids. Sulfate should generally be exempted.
For rationale see Section 201.
SULFAMIC ACID SULFATION (204)
This reaction is rather limited in scope, but can have a high
discharge because of washdown after each batch. Contaminants
will be unsulfated ethoxy alcohols, sulfamic acid and ammonium
ether sulfates.
The MBAS test and a limitation for the process will be most
useful for control. Because the MBAS test does not pick up
nonionic surfactants. BODjj and COD are needed to control the
overall organic load. As usual, pH control will be needed since
sulfamic acid is a strong acid.
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Sulfamic acid hydrolyzes to ammonium acid sulfate in water so
that no control is needed unless the receiving water is close to
its limit for nitrogen and sulfate.
The organic contaminants from this process will be feedstock,
fatty alcohols, alcohol ethoxylates and alkyl phenol ethoxylates.
Also, the sulfated products and the final ammonium, sodium and
triethanol amine salts will be found. Inorganics will be hydro-
chloric and sulfuric acids plus ammonium and sodium ions.
Limitations have been established for total organics by
specifying BOD5 and COD values. MBAS should be measured and
controlled. Raw material spills can be controlled by specifying
suitable values for oil and grease and suspended solids. As
usual, pH needs adjustment to the 6.0 - 9.0 level.
NEUTRALIZATION OF SULFURIC ACID ESTERS AND SULFQNIC ACIDS (206}
In this process the organic acids produced by sulfation and
sulfonation are reacted with bases to produce the desired salts.
Therefore, contaminants will be the products of processes 201,202
and 203. In addition, the neutralized products and the various
cations will be present.
The MBAS test, and a limitation thereon, will be important in
controlling contamination from this process. BOD5 and COD
allowances will determine overall organic contamination. To
assure a neutral waste water, pH adjustment will be necessary.
Oil and grease and suspended solids should be minimal but
specifications are needed for unusual spills.
Control of inorganic sulfate, potassium, sodium and ammonium ions
is believed unnecessary for most receiving streams.
SPRAY DRIED DETERGENTS J207)
Effluents from this process will contain all of the many
ingredients used in dry detergent powders: LAS, amide, nonionic
and alcohol surfactants: sodium phosphate, carbonate and silicate
builders; carboxmethyl cellulose, brighteners, perborate, dyes,
fillers and perfumes.
An MBAS limit will handle anionic surfactants, but COD and BOD5
tests are needed to estimate other surfactants. Careful
attention needs to be paid to BOD5/COD ratio since the various
surfactants can inhibit or react slowly with unacclimated BOD5.
cultures. ~
The suspended solids test will serve to limit insolubles and the
oil and grease limit is needed for spill of oils from the spray
tower.
Specific limits have not been recommended for carbonate,
silicate, phosphate and sodium ions. The condition of the
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receiving stream should be determined by the permit officer
before limiting these contaminants.
LIQUID DETERGENTS (208)
These products are made by simple blending so effluents will
contain the starting ingredients. High levels of organic surface
active agents can be expected from washdown and cleanup. Heavy-
duty liquid detergents will also contain potassium phosphate,
silicate and citrate builders and solvents (ethanol).
Hydrotropes (sodium xylene sulfonate and urea) will also be
found.
To control total organics the BODjj and COD levels have been
specified. MBAS limits have been set to control the important
anionic surfactants. Limits on pH, oil and grease, and suspended
solids have been set but control measures should be unnecessary.
Except for the generally innocuous inorganic salts, levels for
all contaminants have been specified.
DRY DETERGENT BLENDING (209)
This process usually has a very low effluent level. Any
contaminants will be the same as those discussed in Section 207 -
spray dried detergents. Our rationale for limiting BOD5, COD,
pH, suspended solids, MBAS and oil and grease are the same also.
DRUM DRIED DETERGENTS (210)
Almost exclusively devoted to the manufacture of industrial
detergent powders, this process uses a wide variety of raw
materials. They find their way into waste water flows through
spills and washouts. BOD5, COD and surfactant (MBAS) limits will
govern these sources, coupled with pH.
There should be no oil and grease appearing in any waste water
from this process.
DETERGENT BARS AND CAKES (211)
Processing of detergent bars is almost identical with soap bars.
However, the wastes will contain synthetic surfactants.
Therefore, in addition to setting limits on BOD5, COD, pH,
suspended solids and oil and grease, it is necessary to specify a
limit on MBAS.
The rationale for the limits and parameters will be found under
process 106.
Industrial Cleaners
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Industrial cleaning compounds are also manufactured in plants of
the soap and detergent industry. Insufficient data was obtained
to make specific recommendations on the multitude of compounds
employed but some guidance can be given. Industrial cleaners
make up about 10 percent of the industry output. The studies of
the Organic and Inorganic Chemicals Industries are expected to
provide much useful treatment data on some of the more exotic
chemicals. The phosphates, silicates, carbonates and caustic
alkalis which are employed will create the same basic situations
as are discussed in processes 207, 208 and 209. Similar
treatment procedures and guidelines also apply.
Other material not sufficiently characterized but which might be
expected in the industrial waste waters are hydrogen fluoride,
sulfamic acid, phenols and cresol, chlorinated hydrocarbons,
complex organic and inorganic corrosion inhibitors, and exotic
surfactants. Fluorides can be easily precipitated with lime.
Sulfamic acid and cresol are readily biodegradable if
concentrations are kept low. The chlorinated hydrocarbons may
have to be removed by solvent extraction or carbon absorption.
Some corrosion inhibitors used in acids for industrial cleaning
are complex organics which will require individual study. The
exotic surfactants will include phosphoro-, fluoro- and silico-'
organo compounds which have unknown treatat>ility. Nonionic,
amphoteric, and low molecular weight wetting agents with
different treatability can also be expected. The limits on BOD{>,
COD, suspended solids, surfactants, oil and grease and pH should
effectively control industrial cleaners in the subcategories
involved in their production, but the area of industrial cleaners
merits additional study.
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SECTION VII
CONTROL AND TREATMENT TECHNOLOGY
Introduction
The key to great reductions in the pollution load from the soap
and detergent industry is lower process water usage. Those
processes using the most process water per unit mass of product
made are also the greatest contributors of pollutants.
One of the biggest improvements would be either changing the
operating techniques associated with the barometric condensers or
replacing them entirely with surface condensers. Complete
replacement would reduce many fold the use of water in most
processes and at the same time cut down greatly on the amount of
organics now being sent to sewer. These organics normally have a
market value (when further purified) which may provide a positive
payout on the improvement introduced.
Barometric condenser operation could be greatly improved by
recycling the water through a fat skimming operation (where
marketable fats and oils could be recovered) and then through
cooling towers. The only waste would be a continuous small
blowdown from the skimmer to keep soluble materials within
acceptable limits. Fat splitting operations which have
barometric condensers equipped with such cooling and skimming
equipment already meet the recommended guidelines with
considerable ease.
Another area where a large reduction in water usage could be
effected is in the manufacture of liquid detergents. This can be
attained by installation of additional water recycle piping and
tankage and by the use of air rather than water to blow out
filling lines. This latter change will also minimize the loss of
finished product.
One of the large integrated plants making both soaps and
detergents has achieved almost zero discharge of pollutants
through a painstaking, ten-year effort. One of the first tasks
which had to be undertaken, and still the biggest obstacle for
most fairly old integrated plants, was identifying and untangling
the waste water lines which now lead to the sewer. Only after
such identification, monitoring and study could the effluents be
managed better.
With few exceptions, the contaminants in waste waters from the
soap and detergent industry are really saleable products in
disguise, especially those relating to distillation equipment and
entrainment separators. Wherever a distillation is carried out,
whether on a batch basis or by multi-component continuous
fractionation, there is an entrainment of liquid droplets from
one tray of a tower to the tray above. This is essential in
order to accomplish good vapor-liquid contacting and to make the
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efficiency of the physical transfer of the highest possible
order. However, it does result in carrying droplets of liquid by
the vapor from the stage below to the stage above. The use of
one or two additional special trays in a distillation column,
whether used in concentration as in glycerine manufacture or used
for the separation of components as in fatty acid manufacture,
will not only eliminate carryover in the form of entrainment but
will lead to a more complete separation and a higher purity of
each component of a multi-component distillation feed.
NATURE OF POLLUTANTS
The soap and detergent industry produces wastewaters containing
both conservative and nonconservative pollutants which must be
treated, removed from the waste stream, and ultimately disposed
of under controlled conditions. The important nonconservative
pollutants consist of organic raw materials, fats and oils and
lost portions of finished product, soap and/or synthetic
detergent. Mineral solids, catalysts and builder materials such
as borate and phosphate also appear in the effluents in moderate
concentrations. Some of these substances reach polluting concen-
trations in plant effluents which then have to be treated. The
pollutants of primary concern, together with the concentration
ranges within which they are generally found in plant raw waste
effluents are as follows:
1. Oils and greases (0-3400 mg/1)
2. Suspended organic material other than oils and
greases (0-30,000 mg/1)
3. Dissolved or finely dispersed colloidal organic
substances which contribute to the chemical and
biochemical oxygen demands. (100-12,000 mg/1)
4. Certain organics with surfactant properties.
(0-1700 mg/1)
In addition to pollutants per se, the alkalinity or acidity of
wastes is also a primary concern and may mandate the treating of
a plant effluent.
Of secondary concern in raw wastes are the following pollutants:
1. Boron or borates (less than 1 mg/1)
2. Phosphates (25-1000 mg/1)
3. Dissolved mineral solids (0-250,000 mg/1)
4. Zinc and barium (less than 1 mg/1)
It should be noted that the higher values in the ranges listed
above are representative of small individual waste streams and would not
be representative of the total raw effluent for a plant or even a subcategory.
Since phosphate compounds are used in the manufacture of several
types of detergent, some of them inevitably find their way into
the process waste streams. The concentrations actually measured
vary widely and the data are not sufficiently complete to make
-------
absolute judgments concerning typical levels for many of the
operations carried out in the industry. However, some
generalizations can be made.
In the closely controlled, well operated, integrated
manufacturing facilities examined as a part of the present study,
where phosphoric acid type cleaners were not being produced, the
concentrations of phosphorus contained in the combined raw waste
was generally under 25 mg/1 as phosphorus. In those same
facilities the average concentrations were typically 5-10 mg/1 as
phosphorus; i.e., of the same order as is contained in domestic
sewage.
Table 2 indicates the treatment technology which can be applied
to the appropriate waste streams for removal of specific
pollutants of concern.
More specific consideration of the best practicable control
technology currently available and the best available technology
economically achievable is contained in Sections VIII, IX and X.
DISCUSSION OF TREATMENT TECHNIQUES
The treatment technologies discussed are standard and in routine
use. Operating and design techniques are well established and
have been reported upon extensively in the literature.
Therefore, only a brief discussion of such operations and
processes is included in this report. A list of the major
pollutants and treatment methods usually employed to handle them
are given in Table 2. Removal efficiencies for some of these
treatment methods are given in Table 3.
Oil and Grease Removal - This may be accomplished by the ap-
plication of any one, or a combination of three basic separation
methods - gravity separation, physical filtration, or adsorption.
The gravity separators are designed to handle loads of 20,500-
41,000 1/day/sq m (500-1,000 gpd/sq ft) of surface. The filters
are normally operated at 205-615 1 /min/sq m (5-15 gpm/sq ft).
Carbon and other related solid phase adsorption operations
require approximately 0.15-0.68 kg (1.0-1.5 Ib) of adsorbent per
O.U5 kg (1 Ib) of oil removed. Flotation operates very much the
same as the sedimentation operation in terms of over-all
efficiency. Air rates are usually maintained around O.OOU-0.011
cu m/min/cu m (C.5-1.5 cu ft/min/100 gal) of recycled flow.
Chemical doses of FeC13, alum, or lime vary from 50-150 mg/1.
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TABLE 2
Treatment Methods Used in Elimination of Pollutants
Pollutants
Free and emulsified
oils and greases
Suspended Solids
Dispersed Organics
Dissolved Solids
(Inorganic)
Unacceptable Acidity
or Alkalinity
Sludge obtained from
or produced in
process
Treatments
1. Gravity separation
2. Coagulation and sedimentation
3. Carbon adsorption
U. Mixed media filtration
5. Flotation
1. Plain sedimentation
2. Coagulation-sedimentation
3. Mixed media filtration
1. Bioconversion
2. Carbon adsorption
1. Reverse osmosis
2. Ion exchange
3. Sedimentation
U. Evaporation
1. Neutralization
1. Digestion
2. Incineration
3. Lagooning
4. Thickening
5. Centrifuging
6. Wet oxidation
7. Vacuum filtration
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Table 3
Relative Efficiency of Several Methods Used in Removing Pollutants
Pollutant and, Method Efficiency (Percentage of Pollutant Removed]_
Oil and Grease
API type separation
Up to 90 percent of free oils and greases.
Variable on emulsified oil.
Carbon adsorption
Up to 95 percent of both free and
emulsified oils.
Flotation
Without the addition of solid
phase, alum or iron, 70-80 percent of
both free and emulsified oil.
With the addition of chemicals,
90 percent
Mixed media filtration
Up to 95 percent of free oils.
ciency in removing emulsified
oils unknown.
Effi-
Coagulation-sedimentation
with iron, alum or solid
phase (bentonite, etc.)
Suspended Solids
Mixed media filtration
Coagulation-sedimentation
Up to 95 percent of free oil.
90 percent of emulsified oil.
70-80 percent
50-80 percent
Up to
Chemical Oxygen Demand
Bioconversions (with final
clarifier)
60-95 percent or more
Up to 90 percent
Carbon adsorption
Residual Suspended Solids
Sand or mixed media filtration 50-95 percent
Dissolved Solids
Ion exchange or reverse osmosis Up to 99 percent
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Coagulation and Sedimentation - These units are designed to
provide between 30 and 60 minutes of coagulation time and are
normally designed for surface loading rates of 16,400-61,500
I/day sq m (400-<1500 gpd/sq ft) depending upon the nature of the
waste.
Bioccnyersign Systems - Bioconversion is a biological method of
removing pollutants from waste water. Its use involves one or
more of the following:
1. Aerated lagoons
2. Extended aeration
3. Activated sludge
4. Contact stabilization
5. Trickling filters
While both aerobic and anaerobic sludge digestion are
bioconversion processes, they are not used to remove pollutants
directly from the waste stream but rather to further treat
materials already removed or currently being generated as a part
of the treatment operation. Bioconversion units based on the use
of activated sludge or one of the basic modifications thereof are
designed on the basis of 90-363 mg (0.2-0.8 Ib) of COD per 0.45
kg (1 Ib) of dry biomass. Depending upon the nature of the
organics, this loading will provide average removals in excess of
80-90 percent with daily maximum discharges not exceeding three
times the average discharge. Trickling filter systems are
designed in a more empirical fashion using one of the many
formulae in the literature relating efficiency to a real loading
depth, recycle rate and hydraulic load.
Carbon Adsorption Systems - These are of two general types; those
which use a more or less fixed carbon bed, and those which use
powdered carbon and recover the spent carbon in an accompanying
clarifier. The carbon is usually loaded at rates of 45-227 g
(0.1-0.5 Ib) of pollutant per 0.45 kg (1 Ib) of carbon. At
conventional surface loadings, spent powdered carbon is easily
recovered in a clarifier after coagulation with inorganic salts
or organic polyelectrolytes.
Carbon regeneration is a comparatively new art. While some
regenerative type systems do exist, they are neither common nor
completely satisfactory, In carbon regeneration, there are a
number of technological questions still to be answered. For
example, movement of the carbon to the furnace, attrition rates,
control of oxygen to prevent explosion. All of these questions
should be carefully examined prior to entering upon a major
program utilizing the carbon adsorption waste treatment process.
However, if the nature of the wastes to be treated clearly
indicate the desirability of using the process, the above
considerations should not be viewed as absolute deterrents.
Filtration for Removal of Suspended Solids _ See discussion of
oil"removal.
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Dissolved Solids Removal - The design of systems for this purpose
varies widely with the manufacturer. They are evaluated on the
basis of efficiency, water recovery, and the tendency to foul in
the presence of suspended material. Most systems require the
removal of most of the suspended solids prior to treatment. Some
require virtually complete removal of both suspended solids and
dissolved organic solids. Over-all water recovery tends to vary
from 65-90 percent depending upon the particular system employed
and the nature of the waste.
Other Treatment Technique Considerations - In a good part of the
soap and detergent industry, the conversion of raw materials and
the recovery of reaction by-products is carried out on a batch
rather than a continuous basis. This results in effluent streams
which flow sporadically and vary greatly in content and volume.
Because of this, most soap and detergent plants have devised ways
of offsetting such irregular performance and obtaining effluent
streams of a more constant nature, usually by providing some
system capacitance, frequently in the form of an equalization
basin.
while it is not recommended that provision be made specifically
for the control of phosphorus, it is recognized that a certain
amount of phosphorus is normally degraded in the normal course of
waste treatment. The following discussion is presented to
indicate how this occurs.
When in the coagulation and sedimentation waste treatment process
lime, alum, or a combination of iron salts is used as the primary
coagulant for the removal of suspended or colloidal material, the
removal of phosphorus may be carried out concomitantly by making
minor adjustments in the mode of operation and the handling of
the sludge. In many cases, a high degree of removal will be
obtained with no change in the standard operating practices. It
depends upon the pH levels employed in lime coagulation and the
level of aluminum or iron salts employed in polyelectrolyte
coagulation. In general, this procedure will produce phosphorus
levels well under 1 mg/1 and under 0.5 mg/1 where an extremely
high level of sedimentation performance is obtained.
In the above mentioned waste treatment process, some phosphorus
is removed as the phosphate salt of the metal cation employed in
the coagulation step. In the case of lime precipitation, pH
values in excess of 9.5 are generally required for a high level
of removal. The actual value depends on the background calcium
in the waste stream and the level of removal required. In the
case of ferric or aluminum phosphate precipitation, 1-3 times the
stochiometric quantity will be required for a high degree of
removal. As can be seen, these quantities of material do not
represent a major addition to the chemical requirements and
indeed a high level of phosphate removal may be incidental to
suspended and colloidal solids removal. Where phosphorus removal
is practiced as a part of an over-all waste treatment operation
which includes bioconversion, a sufficient level of phosphorus
99
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must remain in the stream flowing to the biological system to
support microbial action. On a weight basis, this is generally
of the order of 200 units of COD for each unit of phosphorus.
To facilitate an understanding of the relationship between the
various unit processes involved in the over-all waste treatment
process, the former have been arranged in the approximate order
in which they might occur in a composite waste treatment flow
chart in Figure 20. A similar chart for sludge solids handling
is presented in Figure 21.
SPECIAL OPERATIONAL ASPECTS OF CONTROL TECHNOLOGY
The nature of the treatment scheme proposed herein, coupled with
certain basic characteristics of the industry itself, calls for
special design and operating techniques in order to achieve
satisfactory waste control. The factors involved are discussed
briefly in the following paragraphs.
The industry employs many batch operations which tend to produce
waste of variable character and quantity. As a consequence,
there is often a need for some way of obtaining a more uniform
waste stream from the standpoints of both composition and flow.
Traditionally this has been done by installing mixed equalization
tanks through which the wastes pass prior to being subjected to
the principal treatment. However, these units often present
operating problems of their own. For example:
1. If the waste is not at biostatic concentrations when it
reaches the treatment plant, some bacterial growth will occur in
the equalization unit producing solids and tending to reduce the
oxidation potential of the system to ineffective levels with
accompanying odors and nuisance status.
2. It is necessary to provide a minimum of 0.8 kw/cum (40
hp/1000 gal) to be sure that the wastes in the equalization tank
are completely mixed and that sedimentation will not occur.
On the other hand, if an equalization unit is not provided, unit
operations and processes which are regulated by flow and
concentration will be adversely affected. In minimizing or
eliminating the adverse effects of influent surges, the following
should be considered:
1. Installation of clarification units which can be kept
uniformly over 4 m (12 feet) side water depth. Deep units are
much less subject to upsets by variations in surface loading than
are shallower units of 3 m (10 ft) or less.
2. If a completely mixed first stage activated sludge
bioconversion system is to be employed it should be understood
that the effluent quality will vary with the influent strength
surges. Effluent quality variations can be handled either by
equalization, or by providing a second activated sludge stage of
TOO
-------
COMPOSITE FLOWSHEET
WASTE TREATMENT
SOAP & DETERGENT INDUSTRY
TO REGENERATION
BRINE
RAW
WASTE'
COAGULATION
SEDIMENTATION
BYCONVERSION
SLUDGE-RECYCLE
GREASE & OIL RECOVERY
SLUDGE CONDITIONING
AND
DISPOSAL
SAND OR
MIXED MEDIA
FILTRATION
FIGURE 20
-------
SLUDGE SOLIDS HANDLING
SOAP & DETERGENT INDUSTRY
SLUDGE FROM OILY
WATER TREATER
SLUDGE FROM
COAGULATION & SEDIMENTATION
OVERFLOW TO
PROCESS
OVERFLOW TO
PROCESS
WASTE SLUDGE
FROM BIOCONVERSION
SYSTEM
THICKENING
THICKENING
\r
DEWATERING
VACUUM FILTER
OR CENTRIFUGE
T
TO LAGOON
OVERFLOW TO
PROCESS
HEAT
TREATMENT
LAGOON
DISPOSAL
CAKE TO INCINERATION
OR GROUND DISPOSAL
GROUND
1
DISPOSAL
ASH TO LANDFILL
OR GROUND DISPOSAL
INCINERATION
102
FIGURE 21
-------
the plug flow type. Since the energy per unit/volume
requirements for either option are roughly comparable, the latter
procedure is generally the most cost effective means of dealing
with this problem.
If carbon adsorption is to be employed instead of bioconversion,
an equalized feed stream will be necessary. Regardless of other
considerations, an upstream system capacitance must be provided
if maximum efficiency is to be obtained from the treatment.
Whenever the waste entering a coagulation and sedimentation unit
tends to be highly biodegradable, troubles with gasification in
high solids systems may be anticipated if neutral pH values are
employed for coagulation. Therefore, it is necessary to evaluate
the residence or holdup of solids that can be employed, prior to
deciding upon a treatment system. Plant shutdown for turnaround
or under emergency conditions, particularly if operations cease
for more than two to three days, can result in a diminution in
the effectiveness of bioconversion systems on startup. Under
such circumstances, the advantages of having an equalization unit
of substantial size ahead of the bioconversion unit become
apparent. During turnaround, the equalization unit may be
drained and cleaned, thereby providing the food materials
necessary to sustain the resident biota in the bioconversion
portion of the system. If this is not possible, provision should
be made for the discharge of stored concentrated waste to the
biocenversion unit during plant shutdown.
The equipment associated with the treatment steps proposed herein
does not have extraordinary maintenance requirements. Normal
once per year examination, along with routine maintenance, is the
standard requirement, consideration should be given to providing
unit by-passes or the utilization of design concepts which will
permit routine maintenance without taking the unit out of
service. It should be generally possible to by-pass each
individual unit without taking the plant off the line or markedly
changing the over-all operational efficiency.
Waste treatment works must be well managed to avoid their
becoming public nuisances. If not handled properly, lagoons, the
incineration of sludge, or the regeneration of carbon may
generate objectionable odors. This problem may be eliminated or
controlled by proper location of the units and the use of gas
emission control equipment. In the case of lagoons, proper
operation of the preceding waste treatment units is essential.
Solid Waste Generation Associated with Treatment Technology
Depending on the precise nature of the over-all waste stream,
solid waste may orginate at any one of several points in the
waste treatment process. Please refer to the composite waste
treatment flow sheet. The principal sources of solid waste are :
103
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1. Sludge from the under flow of a gravity type oily water
treater. This sludge would normally be combined with other waste
solids from the process.
2. Sludge withdrawn from the coagulation and sedimentation unit
and combined with other waste sludges or processed separately.
3. Waste sludge which is normally generated in a bioconversion
facility although the units can be designed to approach virtual
steady state between new sludge production and the loss of
resident sludge over the weir and through endogenous respiration.
Process sludges are treated by one or more of the methods
outlined in Figure 21. In rough chronological order, steps
leading to the ultimate disposal or sludge include the following:
1. As a first step, the sludge is thickened in a gravity
thickener or a centrifugal device. In either case, effluent
solid concentrations varying from 3 percent to 10 percent may be
anticipated.. The difference arises from the substantial
differences in the characteristics of the sludges.
2. After thickening, biological sludges may be treated to reduce
moisture content of the ultimate cake. The sludge is then
subjected to heat and pressure to reduce the size and complexity
of the protein and carbohydrate cellular material. This, in
turn, releases bound water. In some cases the sludge is
discharged to a lagoon after this step.
3. In the next step, the sludges are dewatered, either on a
vacuum filter or in a solid bowl centrifuge. In some instances
sludges will have to be conditioned with either organic polymers
or inorganic polyelectrolytes prior to dewatering.
4. Following the dewatering step the sludge may be disposed of
directly or incinerated for the removal of virtually all of the
residual organic matter.
5. Following incineration the ash, which constitutes from 5
percent to 10 percent of the initial mass, is disposed of as land
fill.
104
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SECTION VIII
COST, ENERGY AND NON-WATER QUALITY ASPECTS
There are fewer than a dozen plants associated with the soap and
detergent manufacturing industry which are point source dis-
chargers into navigable waters. Of these plants, only one has a
complete primary-secondary treatment plant comparable to those
found in a good municipal sewage treatment system. There are
several aerated and non-aerated lagoons which experience varying
degrees of success in their ability to reduce the incoming load
to acceptable levels.
Because of the highly variable nature of the wastes which makes
individual treatment prohibitively expensive, most small and
medium-size plants will continue their current practice of
sending their wastes to municipal or regional systems. For this
reason emphasis in this section has been placed on in-plant
controls rather then end-of-pipe treatment.
IN-PLANT CONTROL
There are essentially three sources of in-plant contaminants of
the waste water effluent streams. They are:
1. Impurities removed from raw materials
2. By-products or degradation products made
in the process
3. Very dilute product (in aqueous solution)
resulting from leaks and spills and the
clean out of equipment.
These are discussed in the succeeding paragraphs.
TABLE 4
Range of Water Use by Process
(gal/1000 Ib Product Produced)
(liters/119kg Product Produced)
Batch Kettle Soap 25 - 2345
Fat Splitting 203 - 23,200
Soap Via Fatty Acid Neutralization 31 - 1750
Glycerine Concentration 80 - 120,000
Glycerine Distillation 40 - 65,000
Bar Soap 9 - 2300
105
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Oleum Sulfonation 12 - 90
Air/303 Sulfonation 1 - 240
Chlorosulfonic Acid Sulfonation 184 - 330
Neutralization 2 - 1100
Spray Dried Detergents 14 - 228
Liquid Detergents 75 - 185
Drum Dried Detergents 265 - 400
Detergent Bars & cakes circa 25
Impurities Removal
There are two main sources of impurities which concern the
manufacturers of soaps and detergents. They are the light ends
and color bodies in the fats and oils used in the manufacture of
soap, and the light ends (usually low molecular weight fatty
acids) removed in the flashing and/or distillation of fatty acid
produced from the fat splitting process. In both cases the
processes having high effluent loadings employ barometric
condensers. Replacement of barcmetrics by surface condensers
would appreciably reduce the amount of contamination (approxi-
mately 80 percent) and, of course, all but eliminate the entire
hydraulic loading. The capital cost of this replacement would
amount to approximately $2,00-$3,00/1000 Ib annual capacity of
fatty acid in a plant capable of making 100 million pounds per
year having other capital cost about $60-$70/1000 Ib of annual
capacity. This, however, is not the only way in which the
effluent problem could be minimized. An alternative is to
install an extractive step ahead of the barometric leg where the
light ends are picked up in an oil film to be later distilled for
the recovery of the valuable low molecular weight acids. An
installation of this type has been proven successful
commercially. It has a two year payout. An initial capital
investment of approximately $7-9/1000 Ib annual capacity of fatty
acid produced would be required for a 20 million Ib per year
plant. A reduction in raw waste loadings of approximately 85
percent would be attained.
Still another method of handling the problem is the installation
of a cooling tower with recirculation of condenser water, and
employing a fat skimmer. A periodic blowdown of the skimmer to
sewer would dispose of accumulated solubles, and the fat
recovered would assist in the payout. The cost for such an
installation would be approximately $10-12/1000 Ib of annual
capacity for a 40 million Ib per year plant. Reduction of raw
waste loadings of approximately 75 percent would be anticipated.
Improved performance (approximately 90S removal of both floating
106
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and emulsified oil and grease) of skimmers can be attained at
modes costs by providing chemically assisted flotation. While
this will not improve removal of emulsified coconut oils, it
should be borne in mind that coconut oils constitute 20% or less
of the feedstocks.
Although not strictly an impurity, glycerine is carried overhead
into the barometric condenser water in the process of
concentrating and subsequently distilling the product out of
dilute feeds. It is estimated that the cost of replacing the
barometric legs with surface condensers and appropriate vacuum
equipment would amount to about $21/1000 Ib annual capacity of
glycerine and would reduce raw waste loads by about 90 percent.
This compares with a total cost of around $40/1000 Ib annual
capacity for installation of concentrators utilizing barometric
condensers. The payout for the surface condenser installation
(based on the additional product recovered) is around 10+ years.
These estimates apply to a plant having a 10 million Ib per year
glycerine capacity.
Unfortunately, installation of a recirculating cooling water
system would have no effect upon the effluent loadings in this
case since glycerine is soluble in water in all proportions and
recirculation would only result in higher concentrations in lower
volumes of water. This could be offset by operating the cooling
tower as a biological tower to reduce organics. Further, the
reduced hydraulic load can be treated at lower costs and with
greater efficiency in the typical end-of-pipe biological
treatment systems.
By-product/Degradation Product Control
The dark colored soap (nigre) recovered from batch kettle soap
making can in some instances, constitute a disposal problem. In
the larger, more integrated plants there is usually a market for
the material (e.g. pet soap and industrial lubricants) so that
the disposal of the material is not a total liability. where
this is not the case a modest investment would need to be made
for an accumulator tank where these materials could be acidulated
to break the soap, the fats being recovered and sold and the
balance of the aqueous layer being sent to disposal. An
investment of about $2 - $4/1000 Ib annual capacity of soap would
be needed for this operation. This is not an inconsiderable
amount when related to an already fully amortized older plant,
but it would result in about 75 - 80 percent reduction in raw
waste load. If the fat is recovered, an ultimate payout could be
realized.
Degradation of product occurs most abundantly in the sulfonation
processes, particularly in the start up of an air-sulfur trioxide
unit. In large integrated plants this causes only minor problems
since they can often work off the relatively small amount by
blending it into a large volume material. The small scale custom
sulfonator is the one of concern. He has no economic alternative
107
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but disposal to sewer. Use of a batch countercurrent process
with improved agitation can give improved heat transfer as well
as increased contact of reactants. This can be achieved with an
almost undiscernible cost. In this case, the added capital cost
would amount to about $2.20/million kg ($l/million Ib) of annual
capacity. Utilities consumption would increase less than 10
percent from utilization of a recycling loop for the neutralized
sulfonic acid product stream.
Dilute Product From Cleanouts, Leaks & Spills
Liquid detergent manufacture at present accounts for one of the
higher waste water effluent loadings in the industry. This is
related to the need to clean out the mixing tanks and filling
lines thoroughly when making a product change in the filling
operation. If steam or air (rather than water) were used to blow
the lines clean, the product could be directly reused, or in the
case of steam the more concentrated solutions could be stored and
either reused or disposed of more easily. The cost to the larger
highly integrated plants (50 million Ib per year with a capital
cost of $25-30/1000 Ib of annual capacity) would amount to about
$2 - $3/1000 Ib annual capacity of anhydrous product produced.
Resulting raw waste loads reduction on the order of 50 percent or
greater should be realized.
Additional major sources of dilute product streams are detergent
spray towers' air scrubbers and tower clean outs. A suggested
way in which this could be reduced involves incorporating
concentrated and dilute scrubbing streams in series to chill and
scrub the exit gases from the tower. The concentrated first
stage scrubber stream would be recycled to the crutcher and the
dilute second stage scrubber stream used for the first stage.
The capital cost would amount to about $1.00/1000 Ib annual
capacity for spray towers capable of producing 100 million Ib per
year. This includes cooling facilities to keep the scrubber
water down to an effective chilling temperature. Raw waste
reduction should be approximately 65 percent.
END OF PIPE TREATMENT
Waste water streams from soap and detergent processes are readily
biodegradable, but they do not have uniform flows nor are their
concentrations constant. In most cases there are significant
surges having varying strengths of contaminants. This set of
conditions is very detrimental to the successful operation of a
treatment system. For this reason, small scale operators having
intermittant streams of 10,000 - 50,000 gallons per day of waste
water are almost without alternative to utilization of municipal
sewer systems.
Packaged, off the shelf units, at a cost approximating $600/1000
gal/day, could indeed handle the load for a small plant if it
were consistent in quality, concentration, and flow. None of
these conditions, however, describe the waste waters associated
-------
Table 5
Cost and Energy Requirements Associated
With Various Treatment Methods
o
to
Treatment Procedure
Costs
Power Requirements
Capital
Operational
Oil & Grease
Removal
Hand skimmed
tanks $26-79/1000 1
($100-300/1000 gal.)
Mechanically
cleaned tanks $13-18/1000 1
($50-70/1000 gal.)
Mixed media
filtration $21-66/1000 1
($80-250/1000 gal.)
Flotation
Carbon
adsorption
$11-37/1000 1
($49-140/1000 gal.)
$26-210/1000 1
($100-800/1000 gal.)
$5.00/day
None
$0.008-0.026/1000 1 0.19-0.57 kw/1000 cu m/day
($0.03-0.10/1000 gal.) 1-3 hp mgd
$0.032-0.105/1000 1 1.52-2.85 kw/1000 cu m/day
(0.12-0.25/1000 gal.) 8-15 hp/mgd
$0.03-0.11/1000 1 1.14-2.85 kw/1000 cu m/day
($0.12-0.40/1000 gal.) 6-15 hp/mgd
$0.22-0.66/kg oil
($0.10-0.30/lb oil)
0.95-1.9 kw/1000 cu m/day
5-10 hp/mgd
-------
Table 5
(cont'd)
Treatment Procedure
Costs
Power Requirements
Capital
Operational
Carbon Adsorption
System
Fixed carbon
in column $26-79/1000 1
($100-300/1000 gal.)
Powdered car-
bon fed prior
to coagulation
& sedimentation
void
$6-26/1000 1
($25-100/1000 gal.)
Final
Clarification $13-40/1000 1
($50-150/1000 gal.)
Effluent
Filtration
$21-69/1000 1
($80-260/1000 gal.)
Reverse Osmosis
Systems£79-158/1000 1
($300-600/1000 gal.)
$0
($0
,04-0.132/1000 1
15-0.50/1000 gal.)
0.95-1.9 kw/1000 cu in/day
5-10 hp/mgd
$0.
($0,
$0,
($0,
$0.
($0.
$0,
($0,
04-0.132/1000 1
15-0.50/1000 gal.)
008-0.019/1000 1
03-0.07/1000 gal.)
013-0.040/1000 1
05-0.15/1000 gal.)
079-0.269/1000 1
30-1.00/1000 gal.)
0.95-2.85 kw/1000 cu m/day
5-15 hp/mgd
0.19-0.57 kw/1000 cu m/day
1-3 hp/mgd
0.95-1.9 kw/1000 cu m/day
5-10hp/mgd
190 kw/1000 cu m/day
1000 hp/mgd
-------
Table 5 (cont'd)
Treatment Procedure Costs Power Requirements
Capital Operational
Suspended Solids
Removal
Coagulation &
sedimentation $13-40/1000 1 $0.013-0.024/1000 1 0.19-0.57 kw/cu m/day
($50-150/1000 gal.) ($0.05-0.09/1000;gal.) 1-3 hp/mgd
Chemical
addition $0.003-0.013/1000 1
($0.01-0.05/1000 gal.) Fractional mgd
Mixed Media
Filtration & Flotation - See Oil & Grease Removal
Bioconvers ion
Systems
Activated
sludge $29-73/1000 1 $0.013-0.039/1000 1 19-95 kw/1000 cu m/day
($110-275/1000 gal.) ($0.05-0.15/1000 gal.) 100-500 hp/mgd
Aerated Lagoons
$28-53/1000 1 $0,016-0.029/1000 1 19-95 kw/1000 cu m/day
($70-2000/1000 gal.) ($0.04-0.12/1000 gal.) 100-500 hp/mgd
Extended
aeration $21-79/1000 1 $0.013-0.053/1000 1 19-95 kw/1000 cu m/day
($80-300/1000 gal.) ($0.05-0.20/1000 gal.) 100-500 hp/mgd
-------
Table 5 (cont'd)
-Power cost taken at $0.01 KWH
-Attendance @ $5.00/hour
-Manufacturer data used for power requirements
-Plant sizes are generally across 0.01-0.19 kw/1000 cu m/day (0.1-1.0 MGD) to show
cost variation and economy of scale.
-------
with operations of the conventional small or large plant. An
alternative could be the installation of a large equalization
basin, but it would be prohibitively expensive for a small
operation. Further, the typical plant is usually located in a
metropolitan area where the availability of enough land poses an
insurmountable problem.
In plants having daily flows of about 500,000 gallons, the
capital cost for end of the pipe treatment can be expected to run
around $2,000,000 with an operating cost approaching $900/million
gallons. Best practicable control treatment currently available
would most likely include chemical precipitation and equalization
followed by an activated sludge unit and final clarification. A
viable alternative for small plants is an aerated lagoon. Such
lagoons should have 40-50 hp aeration per million gallons
capacity and some provision for clarification of the final
effluent with return of the sludge to the lagoon.
Best available technology economically achievable would
incorporate a final polishing operation, such as mixed media
filtration or carbon absorption, or a second stage activated
sludge unit with plug flow operation. Incorporation of such
polishing steps should result in at least 50-75% reduction of
pollutants contained in the effluent from the biological
treatment and reduce variability in the quality of discharge.
ENERGY REQUIREMENTS
With the introduction of surface condensers to replace the
barometrics, utility costs (including power) will increase.
Generally, in those processes requiring capital modification
because of guideline recommendations, the utility costs will rise
an average 222/1000 Ib of product manufactured. About It of this
is due to direct power needs, the rest being for steam, cooling
water, etc.
As might be expected, the processes impacted the most are
glycerine concentration and distillation which amounts to about
$7,80/1000 Ib.
NON-WATER QUALITY ASPECTS
There is very little non-waterborne waste generated in the
production of soaps and detergents. Almost all (99+ percent) of
the raw materials entering the soap and detergent processes end
up as packaged products for sale to the household or industrial
consumer. Modest amounts of solid wastes end up in sanitary
landfill operations.
In the operation of dry filling lines there are infrequent
problems with the mechanical equipment that result in damaged
cartons. This same problem applies with many of the operations,
including warehousing. Wherever possible, the product is
recycled back into the manufacturing process unless it becomes
-------
excessively contaminated. At most, one would expect several
hundred pounds per day of solid wastes being sent to a sanitary
landfill for disposal from a large plant.
During spray drying tower cleanouts, there often will be caked,
charred material unsuitable for recycle. This would amount to
about 1000 Ib per week from a very large plant; again, this
material would be sent to a sanitary landfill.
Sludge from waste water treatment will also be an input into
sanitary landfill operations. One system in operation pumps the
sludge from the biotreater into the chemical treater where it
precipitates with the addition of lime. The settled precipitate
is pumped to a settling basin where the sludge builds up to a
depth worthy of disposal, whereupon the "solids" are then taken
to the landfill.
Conversion of air contamination problems into waste water
problems is on the increase in the soap and detergent industry.
Soap dust from bar soap manufacture, and fines in exit air from
the detergent spray tower are being dissolved in scrubber water
to be ultimately treated in sewage systems. This is an ideal way
to maximize the disposal alternatives. The products are
biodegradable and readily handled in already existent standard
treatment facilities.
IMPLEMENTATION OF TREATMENT PLANS
The equipment required for implementing the waste treatments
discussed in the preceding sections of this report are available
as off-the-shelf items or they may be found in manufacturers'
catalogs. In the present economy the construction manpower is
generally available, although short term local variations in
availability are to be expected. However, virtually all of the
work required would be carried out by the general contractor
normally involved in the construction of sewage and industrial
waste treatment works.
Depending upon the waste treatment employed and the precise unit
process under consideration, the land requirements will vary from
as little as one-half acre to as much as three or four acres. It
is likely that, for the industry as a whole, a good mean land
requirement would be of the order of 0.4 to 0.8 ha (one to two
acres).
The basic costs and relative efficiencies of the waste treatment
processes outlined in the composite waste treatment flow chart
have been summarized in Table 5. The capital and operating costs
were derived from actual plants which have been constructed
within the past few years. The higher range costs and capital
are applicable to waste water flows of 50,000 - 100,000 gallons
per day. The lower end of the range is applicable to volumes of
2-3 million gallons per day. The data in the table were
adjusted upward and expressed in terms of 1972 dollars.
-------
Regarding operational costs, the figures cited are direct costs
only. They do not include any administrative, overhead, fringe
benefits or directly charged laboratory support. If these costs
were to be included, the total would be roughly double.
Sludge conditioning and disposal costs are highly variable,
depending upon the nature of the sludge and the procedures
followed. The cost brackets for the sequences outlined in Figure
20 are shown in Table 6. It is assumed that land is availabl
for lagoon and landfill disposal of sludge and ash.
115
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Table 6
Cost of Sludge Conditioning and Disposal Operations
Procedure
Costs
Power Requirements
1. Thickening-
influent at
5000 mg
2. Lagooning
3. Heat Treatment
Capital
Operational
$1800-6400/metric ton
($2000-7000/ton)
$1.60-6.40/metric ton Fractional/tpd
($1.80-7.00/ton)
Depends upon land cost entirely
$13,640-45,400/metric
($15,000-50,000/ton)
ton $4.50-13.60/metric ton
($5-15/ton)
181-454 hp/tntpd
200-500 hp/tpd
Dewatering
4.
Vacuum Filtration $103-297/m2
(95-275/sq ft)
5. Centrifugation
6. Incineration
$455-909/mtpd
($500-1000/tpd)
$136,400-681,800/mtpd
($150,000-750,000/tpd)
$7.30-31.80/metric ton
($8-35/ton)
$4.55-22.70/metric ton
($5-25/toh)
$4,55r22.70/metric ton
($15-50/ton)
22.7-68.2 hp/mtpd
22-75 hp/tpd
45.5-90.9 hp/mtpd
50-100 hp/tpd
182-273 hp/mtpd
200-300 hp/tpd
17.2-68.9 1 of
fuel oil/metric
ton (5-20 gal.
fuel oil/ton)
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SECTION IX
BEST PRACTICABLE CONTROL TECHNOLOGY
CURRENTLY AVAILABLE
Introduction
One of the first steps in the development of guidelines was the
determination of raw waste loadings in the waste water flows for
each subcategory in terms of kg/kkg (Ib of pollutant/1000 Ib) of
anhydrous product produced in that subcategory. The raw waste
loading to be expected from the best practicable technology was
established and the guidelines values defined as appropriate
reduction of the raw waste load, e.g., reasonable expectancy of
any treatment plant having a biological secondary treatment
process to attain 90 percent reduction of BOD5.
Wherever appropriate, attention was given to in-plant controls to
minimize the raw waste load. Thus, best practicable control
technology may be defined as good current in-plant control
followed by an end-of-pipe system consisting of adequate
equalization, efficient biological treatment (e.g., extended
aeration) and final clarification.
For several soap and detergent processes a negligible discharge
has been achieved by most manufacturing plants. Best practicable
control technology currently available guidelines give each of
these processes a very small but finite effluent allowance
because of one or more of the following reasons:
1. The product in the effluent stream is so degraded it would
be unsuitable for incorporation in the final product and must
thus be disposed of.
2, The waste water source is so dilute as to require undue amounts
of heat energy to recover the dissolved solids content.
3. The material in the waste water is quite biodegradable; there-
fore, it is readily handled by the receiving treatment plant.
In those categories where the guidelines have been set
particularly low, the permit writer should be alert to the
occasional need to make spot increases in these limits. Upsets
and mechanical problems requiring cleanouts may crop up, rare
though they may be. This will be particularly critical for small
plants (under $500,000 in gross proceeds). The larger integrated
plants have sufficient flexibility in their ability to recycle
the contents of waste streams to minimize their need for spot
increases.
In a few processes there are some relatively heavy discharges of
salt and sodium sulfate. No limit has been established for these
very low toxicity materials since (1) they will be highly diluted
by other process effluents before becoming a point discharge and
(2) the permit writer will undoubtedly want to evaluate the
117
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background levels in the receiving
levels, if any, should be established.
waters and determine what
No maximum delta temperature was established since the dif-
ferential between inlet and outlet process water temperatures is
quite modest, at most around 17°C (30°F), and much of the heat
would be dissipated in the waste treatment process.
The interrelationship of air and water pollution problems became
quite apparent in this study. Increasingly stringent air
emission standards have set performance requirements beyond the
ability of dry recovery systems available on detergent spray
towers. Wet scrubbers have been employed which now allow the air
effluent to meet those standards, but result in a substantial
water flow and a correspondingly higher water pollutant loading.
In every instance in the following guidelines, the pH of the
point source discharge is required to be between 6.0 and 9.0.
With but few exceptions this requirement will be met by the
mingling of individual raw waste streams in the treatment
facilities and will not require special pH adjustment.
SOAP MANUFACTURING
101 - SOAP MANUFACTURE BY KETTLE BOILING
General
This ancient art has been carefully scrutinized by all of its
practitioners to minimize cost and the avoidable loss of
marketable products where the installed capital permits. Even in
the area of very high quality soaps there still appears to be a
preference for this well established process.
There are essentially two main streams carrying away waste from
this source (in actual practice there may be more subsidiary
sources). They are typified by the blocks indicated in the
simplified flow diagram given below:
r => Neat Soap
Fats &
Oils
->--
Solid
Waste
Pre
Treatment
— 1 ^,
Liquid
Waste
->-
Kettle
Boil
J, L
Spent
Lye
•I
*— ^Rec)
v
rcle 1
[Nigre U_
Glycerine
Recovery
Refining [,.
>
t
Dark Soaps
to Market
Soap Scrap
Recycle
Liquid Waste
WASTEWATER SOURCES IN SOAP MANUFACTURE
FIGURE 22
118
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The liquid waste from fat pretreatment will normally be a fat in
water emulsion of modest BOD5_, with perhaps some clay and other
organics. However, the stream from nigre processing, often just
a purge, will be very rich in BOD5 and contain some sodium
chloride and sodium sulfate. Some soap manufacturers do not, at
present, completely process their nigre but run it directly to
sewer. This is a point, for some, to improve in effluent
control.
Raw Waste Loading
The following are the expected thirty day average raw waste
loadings which would be entering a waste treatment plant:
BOD5 - 6 kg /kkg (6 lb/1000 Ib) anhydrous soap
COD - 10 kg /kkg (10 lb/10001b) anhydrous soap
Suspended Solids - 4 kg /kkg (U lb/1000 Ib) anhydrous
soap
Oil and Grease - 0.9 kg /kkg (0.9 lb/1000 Ib)
anhydrous soap
Best^Practicable Control Technology Currently Available Guidelines
On a thirty day average basis the following parameter values are
recommended:
BOD.5 - 0.60 kg/kkg (0.60 lb/1000 Ib) anhydrous soap
COD - 1.50 kg/kkg (1.50 lb/1000 Ib) anhydrous soap
Suspended Solids - O.40 kg/kkg (O.UO lb/1000 Ib)
anhydrous soap
Oil and Grease - 0.10 kg/kkg (0,10 lb/1000 Ib)
anhydrous soap
pH 6.0 - 9.0
In the event of upset in either process or treatment, startup or
shutdown procedure, a value of three times that indicated above
should be considered, provided that over any given thirty day
period the recommended average is maintained.
Best^Practicable Control Technology Currently Available
In many soap plants there are no access points in the floor to
the sewer. This makes good housekeeping unavoidable. All leaks
and spills are promptly attended to and recycled within the
process.
119
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The guidelines limitations can be attained by the production (and
marketing) of low grade soap from the nigre, recovery of fats
from acidulated sewer lyes and nigre, and secondary (biological)
treatment of the resulting waste.
Rationale and Assumptions
Fat saponification is carried out counter-currently where the
aqueous caustic stream is exhausted in a final reaction with
fresh fat. At the other end of the process the nearly fully
saponified fat is completely reacted by coming into contact with
fresh caustic. Salt recycle becomes automatic in that energy
required to concentrate the glycerine stream automatically
concentrates the salt. Filtration of the evaporator product
provides the recycle salt. There is still a substantial amount
of salt that goes to the sewer via the bleed of the nigre.
Phase relationships of electrolyte, soap and caustic content
largely govern their concentration and use to maintain proper
soap solubility. Within these constraints good manufacturing
management will minimize the total constituents going to sewer.
At present, this process can be brought close to no discharge
only at the expense of the smaller soap manufacturers who do not
exhaust their nigre. The recommended settling and acidulation
tank will go a long way toward attaining this goal.
Most kettle boil soap making equipment is several decades old and
represents fully amortized capital. The soap market is not noted
for its dynamic expansion.
102 - FATTY ACID MANUFACTURE BY FAT SPLITTING
General
The waste water effluents for disposal come from essentially
three sources; pretreatment of the fat, light ends emitted from
the fat splitter and the fat still, and the water solubles left
in the acidulated still bottoms after the recycleable fats are
removed and recovered.
The light ends mentioned above are found in the condensate from
the barometric condenser and include short chain fatty acids and
unsaponifiables. One of the minor contaminants in the stream
coming from the still bottoms is the catalyst. It can be the
sulfate salt of zinc, or other alkaline earth metals.
A simplified schematic is given for the process to indicate the
approximate location of waste water streams.
120
-------
Fatal \
Light
Ends
Fat
Splitter
•^
Glycerine
to
Recovery
t—^—t
-distill
?— '
\
— •)
iBottomsl j
f
Fatty Acid
to Market
Acidulation
& Settling
»
a-
To
Strea
/
ving
m
V
Hater Solubles
& Metals Salts
[Fats Recovery]
FAT SPLITTING
FIGURE 23
121
-------
The following raw waste loading can be expected:
BOD5 - 12 kg /kkg (12 lb/1000 Ib) anhydrous acid
COD - 22 kg /kkg (22 lb/1000 Ib) anhydrous acid
Suspended Solids - 22 kg /kkg (22 lb/1000 Ib) anhydrous
acid
Oil and Grease - 2.5 kg /kkg (22 lb/1000 Ib) anhydrous
acid
Included in this loading are waste water flows from: fats
treatment, fats splitting, fatty acid distillation and still
bottoms disposal.
Best Practicable Control Technology Currently Available Guidelines
On a thirty day average, the following parameter levels are
recommended:
BOD5 - 1.20 kg/kkg (1.20 lb/1000 Ib) anhydrous acid
COD - 3.30 kg/kkg (3.30 lb/1000 Ib) anhydrous acid
Suspended Solids - 2.20 kg / kkg (2.20 lb/1000 Ib)
anhydrous acid
Oil and Grease - 0.30 kg/1000 Ig (0.30 lb/1000 Ib) anhydrous
acid
pH 6.0 - 9.0
No additional provision need be made for startup, shutdown or
upsets. Allowance should be made for a threefold increase to
account for variability of treatment over a 24 hour period,
providing that during a thirty day period, which includes this
day of high loading, the recommended average is maintained.
Best Practicable control Technology Currently Available
Essential to the proper performance of the plant is the
incorporation of appropriate fat traps. Indicative of the
technology involved is the flow chart'of a condenser/recovery
unit which could handle the load. Note that the only effluent is
blowdown of the fat settler which handles cooling tower waters.
Due to the high temperatures maintained in the fat splitter, fat
solubility and reaction rate are high so that 99 percent hydro-
lysis can be expected. This makes separation of the condensates
a relatively simple problem, well within the engineering
capabilities of the industry. As noted in the above discussion.
122
-------
it is reasonable to expect that the only materials to be disposed
of are light ends and bottoms.
Rationale and Assumptions
A fats recovery unit for treating fatty acid still bottoms will
help minimize loadings of effluent. This equipment plus
biological secondary treatment will bring the loadings down to
the guidelines level.
102 - FATTY ACID HYDROGENATION
General
As an example of the depth to which some technological studies
have been conducted, the details of fatty acid hydrogenation
processing are presented. Due to the advanced state of the art,
guidelines recommended are to cover all levels.
Technology for AllrLevels
Hydrogenation of fatty acids intended for soap manufacture is
regarded as an additive effluent loading to the fat splitting
operation.
The principal raw materials for the manufacture of fatty acids
used in soap making are coco and tallow fats. These are
generally used in the ratio of about 80 percent tallow fatty
acids to 20 percent coco fatty acids in soap making.
This blend contains in the order of 15 percent of the mono-
unsaturated oleic acid and around 3-4 percent of the doubly
unsaturated linoleic acid. There is very little of the triply
unsaturated linolenic acid. Twenty percent unsaturated fatty
acids in soap is often excessive, consequently the tallow portion
of the fatty acids going into soap manufacture are partially
hydrogenated. This is particularly necessary since tallow
contains up to 50 percent oleic acid esters and as much as 3
percent linoleic esters.
The usual process of making fatty acids and the hydrogenation of
them is given in the schematic flow diagram for the fatty acid
manufacture subcategory. The hydrogenation process is usually
carried out batch wise, particularly for fatty acids destined for
soap making.
The hydrogen source for this process depends upon plant location.
When near a petroleum refinery the hydrogen is often available
from cracking operations and subsequently requires purification.
Hydrogen is also available from electrolytic cells dedicated to
electrolysis of salt for production of sodium and chlorine.
Another common source of hydrogen is that from the de-
hydrogenation of isopropyl alcohol to make acetone. Whatever the
123
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source of hydrogen there will usually be some alkane impurities
that will build up in the recycle use of hydrogen; consequently,
a bleed is necessary and is usually disposed of by burning. This
disposition carries no water effluent and consequently is
disregarded in the guidelines.
The hydrogenation process requires a catalyst. There are two
well-known catalyst systems. One involves the deposition of
nickel as nickel formate onto a pumice or kiesselguhr or a
synthetic product such as Celite. The other commonly used
catalyst is Raney-nickel. Both catalysts are usually suspended
in the liquid to be hydrogenated and subsequently filtered out.
When Raney-nickel is used, the spent catalyst is often recovered
and returned to the manufacturer for reprocessing.
Complete saturation of the fatty acids is not desirable since a
modest amount of cross linking by oxidation helps to make a firm
soap and gives the bar good feel or hand. Though not strictly
true, the hydrogenation of coco and tallow fatty acids is
described as if the same in nature.
Hydrogenation is usually carried out with the catalyst suspended
in the liquid fatty acids in a batch process heated to a
temperature of approximately 175 - 200 C (347 - 392 F) as the
hydrogen passes through the reactor. When the degree of
saturation desired is achieved (as measured by iodine number) the
reaction is terminated. Recovered hydrogen is removed and sent
back to storage via a booster system.
During the hydrogenation process a number of side reactions
occur, some of which cause significant waste water effluent
contamination. Isomerization of the double bond along the chain
does not cause any difficulty. However, occasional chain
scission occurs, resulting in the formation of short chain length
olefins and short chain fatty acids not desirable in the soap
making process. As a result of the fatty acid pre-heating prior
to hydrogenation there is a tendency for some oxidative cross
linking to occur, resulting in a modest amount of polymerized
fatty acids. Storage of the fatty acids at high temperatures
also accelerates this polymerization reaction. some of these
undesirable reactions result in added waste water contamination.
The same raw waste loadings can be expected for all levels of
technology.
Raw Waste Loadings - All Levels
The following raw waste loadings are expected:
BOD5 - 1.5 kg/kkg (1.5 lb/1000 Ib) anhydrous acid
COD - 2.5 kg/kkg (2.5 lb/1000 Ib) anhydrous acid
Suspended Solids - 1.0 kg/kkg (1.0 lb/1000 Ib)
124
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Fatty Acid
Vapors
(Light Ends)
Barometric
Condenser
Slowdown to
Stream
FATS RECOVERY SYSTEM
FIGURE 24
125
-------
anhydrous acid
Oil and Grease- 1.0 kg/kkg (1.0 lb/1000 Ib)
anhydrous acid
On a thirty day average basis, the following guidelines are
recommended:
BOD5 - 0.15 kg/kkg (0.15 lb/1000 Ib) anhydrous acid
COD - 0.25 kg/kkg (0.37 lb/1000 Ib) anhydrous acid
Suspended Solids - 0.10 kg/kkg (0.10 lb/1000 Ib)
anhydrous acid
Oil and Grease - 0.10 kg/kkg (0.10 lb/1000 Ib)
anhydrous acid
pH - 6.0 - 9.0
There is little or no need for an upset allowance in addition to that +-•:
account for variability of treatment.
Rationale and Assumptions
It may be noted that hydrogenation steps in the manufacture of
fatty acids from fats is considered as a supplemental allowance
in view of the occasional use of this process in the general
manufacturing system for soap manufacture. The levels of
effluents suggested and their nature have been outlined above,
based upon a reasonable allowance by careful practice of the art
of hydrogenation and by a careful control and maximum recovery of
effluent streams. There is no particular discernible addition in
the way of capital requirements or utility and power requirements
that would be more than marginal for these effluent limitations
guidelines requirements.
FATTY ACID NEUTRALIZATION
General
This method of neat soap manufacture is a clean process. The
major starting material, fatty acid, has already been subjected
to a severe refining step. During the oil splitting process the
volatile acids and color bodies have been removed.
Neutralization is frequently carried out with soda ash, which
results in the evolution of carbon dioxide. In large
installations, the neutralization may be a continuous process.
Batch operations utilizing stoichiometric amounts of fatty acids
and alkalis may be employed.
126
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Raw Waste Loading
The following raw waste loading can be expected:
BOD5 - 0.1 kg /kkg (0.1 lb/1000 Ib) anhydrous soap
COD - 0.25 kg /kkg (0.25 lb/1000 Ib) anhydrous soap
Suspended Solids - 0.2 kg /kkg (0.2 lb/1000 Ib)
anhydrous soap
Oil and Grease - 0.05 kg /kkg (0.05 lb/1000 Ib)
anhydrous soap
B£§£ Practicable Control Technology Currently Available
Guidelines
On a thirty day average basis the following parameter limits are
recommended:
BOD5 - 0.01 kg /kkg (0.01 lb/1000 Ib) anhydrous soap
COD - 0.05 kg/kkg (0.05 lb/1000 Ib) anhydrous soap
Suspended Solids - 0.02 kg /kkg (0.02 lgs/1000 Ib)
anhydrous soap
Oil and Grease - 0.01 kg / kkg (0.01 lb/1000 Ib)
anhydrous soap
pH 6.0 - 9.0
There is little or no need for an additional upset allowance.
Best Practicable control Technology currently Available
Secondary biological treatment will very adequately handle the
effluent from this process.
Rationale, and Assumptions
This process is carried out using stoichiometric quantities of
all reactants so that the entire content of the reactor is sent
in total to the next processing step; bar soap, soap
flakes/chips, or liquid soap. The product is neat soap at
approximately 70 percent concentration.
Leaks from pump and other packing glands should be gathered and
returned to the process.
104 - GLYCERINE RECOVERY
127
-------
General
The character of the waste water streams from glycerine recovery
will be determined by the source of the dilute streams which are
concentrated. There are two sources of dilute glycerine; one
from the processing of sweet water lyes of kettle boiling soap
and the other from fat splitting.
In the case of the soap making source, a stream which contains 8
- 15 percent glycerine, salt and miscellaneous organic matter is
run to a batch evaporator and concentrated to 60 - 80 percent.
In glycerine concentration the 80 percent product is removed as a
bottoms product and therefore contains all of the original
impurities (less a lot of the original salt), but in a much more
concentrated form. At this point the stream is either sold to a
glycerine refiner or again batch handled in a glycerine still
where the product is taken overhead.
The dilute glycerine stream from fat splitting can be varied
significantly in concentration. It all depends upon how the fat
splitter is operated. Glycerine is a bottoms product from the
splitter. A fairly concentrated glycerine can be obtained if the
yield of fatty acid is sacrificed or the production rate is
diminished.
As the glycerine stream comes from the fat splitter, it is
normally flashed to atmospheric pressure, thereby gaining an
immediately increased concentration of product.
A simplified flow chart of
process is as follows:
the concentrating and distillation
ICondensate to Waste
^
Concentrated
Glycerine
60 - 807.
Glycerine
f.
Salt filtered
or centrifuged
To Soap
Manufacture
GLYCERINE CONCENTRATION
FIGURE 25
Raw Waste Loading
The glycerine concentration and glycerine distillation should be
handled separately. Quite often the glycerine which is
128
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concentrated to 60 or 80 percent is sold to another firm for
further distillation to an assay of 98+ percent glycerine.
Raw waste characteristics are expected to average as follows:
Glycerine Concentration
BOD5 - 15 kg /kkg (15 lb/1000 Ib) anhydrous glycerine
COD - 30 kg /kkg (30 lb/1000 Ib) anhydrous glycerine
Suspended Solids - 2 kg /kkg (2 lb/1000 Ib) anhydrous
glycerine
Oil and Grease - 1 kg/kkg (1 lb/1000 Ib) anhydrous
glycerine
Glycerine Distillation
BODji - 5 kg /kkg (5 lb/1000 Ib) anhydrous glycerine
COD - 10 kg /kkg (10 lb/1000 Ib) anhydrous glycerine
Suspended Solids - 2 kg /kkg (2 lb/1000 Ib)
anhydrous glycerine
Oil and Grease - 1 kg/kkg (1 lb/1000 Ib) anhydrous glycerine
Best Practicable Control Technology Currently Available Guidelines
Separate guidelines should be established for the waste water
effluents for the glycerine concentration step and the final
glycerine distillation since, in many cases, these two operations
are not carried out at the same geographical location nor by the
same manufacturer. In the event both concentration and
distillation are conducted at the same location, the parameter
values of each operation should be combined for a final effluent
allowance.
On a thirty day average basis, the following effluent guidelines
are recommended:
Glycerine concentration
BOD5 - 1.50 kg /kkg (1.50 lb/1000 Ib) anhydrous glycerine
COD - 4.50 kg/1000 Ig (4.50 lb/1000 Ib) anhydrous glycerine
Suspended Solids - 0.20 kg/kkg (0.20 lb/1000 Ib)
anhydrous glycerine
Oil and Grease - 0.10 kg /kkg (0.10 lb/1000 Ib) anhydrous
glycerine
129
-------
pH 6.0-9.0
Glycerine Distillation
BOD5 - 0.50 kg /kkg (0.50 lb/1000 Ib) anhydrous glycerine
COD - 1.50 kg /kkg (1.50 lb/1000 Ib) anhydrous glycerine
Suspended Solids - 0.20 kg / kkg (0.20 lb/1000 Ib)
anhydrous glycerine
Oil and Grease - 0.10 kg /kkg (0.10 lb/1000 Ib) anhydrous
glycerine
pH 6.0 - 9.0
Little or no upset allowance is justifiable and it should not
affect the thirty day average for either glycerine concentration
or distillation. Therefore, the allowance for variability of
treatment is sufficient to cover these subcategories.
Best Practicable control Technology Currently Available
Much of the glycerine concentrating equipment in soap plants is
fairly old. It is operated in a batch manner and apparently the
vapors carry a fair amount of entrainment, as is evidenced by the
amount of salt carryover in the condensate. The long residence
time in the concentrators helps to build up glycerine polymers
and degrades other heavy ends leading to high BOD5 loadings in
the resulting waste water stream.
Where the barometric condenser is continued in use, the in-
stallation of a biological cooling tower with the attendant
recycle of barometric water can materially reduce the raw waste
load.
Rationale and Assumption
In almost all cases observed there has been a significant BOD5_
loading in the barometric condenser water, which is due to the
glycerine escaping the condensing system. Apparently this is not
now regarded as a worrisome economic loss; it does constitute a
high biochemical loading. The employment of more efficient
condensers, eliminating the barometric leg, is one way in which
effluent loadings can be reduced. Another method is the
employment of column reflux in the glycerine evaporators to
reduce glycerine loss.
105 - SOAP FLAKES AND POWDERS
General
130
-------
Nea-t soap is either chill roll, air or spray dried. In either
case, the waste water loading is minimal. There are occasional
washdowns and cleanups required, though rare.
Raw Waste Loading
The leaks, spills and pump gland cooling water will contribute
the following loadings:
BOD5 - 0.1 kg /kkg (0.1 lb/1000 Ib) anhydrous soap
COD - 0.3 kg /kkg (0.3 lb/1000 Ib) anhydrous soap
Suspended Solids - 0.1 kg /kkg (0.1 lb/1000 Ib)
anhydrous soap
Oil and Grease - 0.1 kg /kkg (0.1 lb/1000 Ib)
anhydrous soap
Best Practicable Control Technology Currently Available
Guidelines
On a thirty day average basis, the parameter levels are rec-
ommended to be:
BOD5 - 0.01 kg /kkg (0.01 lb/1000 Ib) anhydrous soap
COD - 0.05 kg /kkg (0.05 lb/1000 Ib) anhydrous soap
Suspended Solids - 0.01 kg /kkg (0.01 lb/1000 Ib) anhydrous soap
Oil and Grease - 0.01 kg /kkg (0.01 lb/1000 Ib) anhydrous soap
pH 6.0 - 9.0
The permit authority may find an occasional situation meriting a
spot increase above these values for unforeseen equipment
washouts in addition to the allowance for treatment variation.
Best Practicable Control Technology Currently Available
Manufacture of flakes and powders has been optimized well to
minimize losses. The systems are maintained dry in normal
practice, thereby no continuous waste water is generated. Only
where there is associated soap reboil (to recover scrap soap) is
there any appreciable amount of effluent generated.
Incineration of scrap soap is one way in which effluents could be
reduced, where applicable and economically feasible. In any
event, biological secondary treatment will appropriately reduce
the waste loadings to acceptable levels.
106 - BAR SOAPS
131
-------
General
Starting with neat soap (approximately 70 percent soap solution
in water) the processes for making bar soaps are quite varied.
The major differences occur in the drying technique. Soaps in
bar form will have a final moisture content varying from 8
percent to over 15 percent, depending upon the particular
properites desired.
Depending upon the particular products made and processes
employed, situations encountered range from those with no waste
water effluents of any kind generated to those having several
scrubber water effluents. Washouts may be a minor source of
pollution, both in terms of effluent volume and pollutant
loadings.
Raw Waste Loading
The following waste water effluent concentrations are regarded as
an average expectation:
BOD5 - 3.4 kg /kkg (3.4 lb/1000 Ib) anhydrous soap
COD - 5.7 kg /kkg (5.7 lb/1000 Ib) anhydrous soap
Suspended Solids - 5.8 kg/kkg (5.8 lb/1000 Ib) anhydrous soap
Oil and Grease - 0.4 kg/kkg (o.4 lb/1000 Ib) anhydrous
soap.
Best Practicable Control Technology Currently Available Guidelines
On a thirty day average basis the following parameter values are
recommended:
BOD5 - 0.34 kg/kkg (0.34 lb/1000 Ib) anhydrous soap
COD - 0.85 kg/kkg (0.85 lb/1000 Ib) anhydrous soap
Suspended Solids - C.58 kg/kkg (0.58 lb/1000 Ib)
anhydrous soap
Oil and Grease - 0.04 kg/kkg (0.04 lb/1000 Ib) anhydrous soap
pH 6.0-9.0
Little or no allowance for upset is required.
Best Practicable Control Technology Currently Available
132
-------
There is concerted effort within the industry to minimize water
use in this particular operation. One of the unresolved
questions is whether air quality restrictions will force other
"dry" operators to incorporate scrubber systems for picking up
elusive soap dust.
The levels specified in the guidelines are readily achievable by
the collection and recycle of soap dust (via dust collectors or
scrubbers) or by secondary biological treatment.
Ratjgnale^and Assumptions
Without much more detailed analysis of the bar soap making
operation it is very difficult to discern just how close to zero
discharge all processes could come without seriously jeopardizing
the product performance, hence the relatively broad allowances.
107 - LIQUID SOAP
general
Neat soap (approximately 70 percent soap and 30 percent water) is
run into a mixing tank to be blended with other ingredients,
filtered if required, and drummed. There may be need for an
occasional equipment washout and a frequent filter cleanout.
Constituents going into these blends are quite varied since their
functions range widely. This kind of business is close to custom
blending due to the high performance nature of many of their
products.
Raw Waste Loading
On the basis of a thirty day average the following raw waste
loadings can be expected:
BOD5 - 0.1 kg/kkg (0.1 lb/1000 Ib) anhydrous soap
COD - 0.3 kg/kkg (0.3 lb/1000 Ib) anhydrous soap
Suspended Solids - 0.1 kg/kkg (0.1 lb/1000 Ib) anhydrous soap
Oil and Grease - 0.1 kg/kkg (0.1 lb/1000 Ib) anhydrous soap
§£ Practicable Control Technology Currently Available
Guidelines "~
As a thirty day average the following effluent parameter values
are recommended:
BOD5 - 0.01 kg/kkg (0.01 lb/1000 Ib) anhydrous soap
COD - 0.05 kg/kkg (0.05 ;bs/1000 Ib) anhydrous soap
133
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Suspended Solids - 0.01 kg/kkg (0.01 lb/1000 Ib) anhydrous soap
Oil and Grease - 0.01 kg/kkg (0.01 lb/1000 Ib) anhydrous soap
pH 6.0-9.0
There may be an occasional need on the part of some manufacturers
to exceed these limits due to a highly varied product mix
requiring washouts more frequently than allowed above.
Best Practicable Control^Technology Currently Available
Secondary biological treatment is adequate to meet the levels
proposed.
Rationale and Assumptions
This processing step is essentially clean, requiring only rare
washouts to prevent cross contamination of widely varied
performance products. Many of these same processors blend dry
detergents requiring comparable frequency of washouts. A
biological secondary treatment is expected to be adequate to
handle the effluents.
201 - OLEUM SULFONATION/SULFATION
General
This chemical process has been optimized in that it is close to a
"push button" operation. It is practically troublefree and
requires washdowns only when there is to be maintenance of the
operating equipment. The leaking pump glands are a problem
typical of this kind of equipment, but modest in nature.
Normally an operator can quickly observe a significant leak and
repair it promptly.
Raw Waste Loading
An average expected raw waste loading is:
BOD5 - 0.2 kg/kkg (0.2 lb/1000 Ib) anhydrous product
COD - 0.6 kg/kkg (0.6 lb/1000 Ib) anhydrous product
Suspended Solids - 0.3 kg/kkg (0.3 lb/1000 Ib) anhydrous
product
Oil and Grease - 0.3 kg/kkg (0.3 lb/1000 Ib) anhydrous product
Surfactant - 0.7 kg/kkg (0.7 lb/1000 Ib) anhydrous product
Best Practicable control Technology Currently Available
Guidelines
134
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The following thirty day average recommendations for effluent
loadings are made with the understanding that there may be some
firms on some occasions requiring additional loadings for
washouts of equipment. Further, during any 24 hour period the
limits could be allowed to slightly exceed 3 times the average as
long as the thirty day average meets the guidelines. This will
account for both variability of operation and treatment.
BOD5 - 0.02 kg/kkg (0.02 lb/1000 Ib) anhydrous product
COD - 0.09 kg/kkg (0.09 lb/10CO Ib) anhydrous product
Suspended Solids - 0.03 kg/kkg (0.03 lb/1000 Ib) anhydrous
product
Oil and Grease - 0.03 kg/kkg (0.03 lb/1000 Ib) anhydrous product
Surfactant - 0.07 kg/kkg (0.07 lb/1000 Ib) anhydrous product
pH 6.0 - 9.0
Some small scale batch operated plants may have great difficulty
in reaching these levels. Consideration should be given by the
permit writing authority for modest relaxation of these levels
where circumstances clearly warrant them.
Best Practicable Control Technology Currently Available
As indicated in the general discussion this process can be
operated continuously in essentially a trouble-free manner.
There is little room for improvement.
Other than the gland leakage and very occasional washouts this
process has no effluent. Gland leakage around pump shafts is a
universal problem wherever liquids are handled, particularly
corrosive liquids. Because of the corrosive nature of the oleum,
thorough washouts are mandatory prior to maintenance work being
carried out on the equipment.
Integrated plants will have little difficulty meeting the levels
of the guidelines. The washwater can be recycled and the leaks
and spills run to the neutralization unit.
Biological secondary treatment will handle the residual wastes
when they occur.
202 - AIR-S03 SULFATION/SULFONATION
General
This process is in as widespread use as the oleum sulfonation
(201), particularly for the sulfation of alcohols and ethoxy-
lates. Although continuous and automatic, the Air - S03 process
135
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is much more inclined to cause product degradation than the oleum
unit.
Whenever the process is started up some material must be
discarded due to low sulfonation making the material below
specification. Promptly upon shutdown a thorough washdown is
required to keep char formation to a minimum. There are mist
knockdown scrubbers which will also contribute to waste water
loadings.
Raw Waste Loading
Average expected raw waste loadings are:
BOD5 - 3 kg/kkg (3 lb/1000 Ib) anhydrous product
COD - 9 kg/kkg (9 lb/1000 Ib) anhydrous product
Suspended Solids - 0.3 kg/kkg (0.3 lb/1000 Ib)
anhydrous product
Surfactant - 3 kg/kkg (3 lb/1000 Ib) anhydrous
product
Oil and Grease - 0.5 kg/kkg (0.5 lb/1000 Ib)
anhydrous product
Practicable Cgntrpl Technology Currently
Guidelines
Thirty day average recommendations are made on a similar basis as
those for Subcategory 201 - Oleum Sulfonation. Because of
product changes or mechanical failures some plants may, at times,
have to exceed established effluent limits. Such cases have not
been provided for in suggested guidelines. Therefore, regulatory
agencies may wish to extend special consideration in such cases
and write appropriate limitations into any permits they issue.
BOD5 - 0.30 kg/kkg (0.30 lb/1000 Ib) anhydrous product
COD - 1.35 kg/kkg (1.35 lb/1000 Ib) anhydrous product
Suspended Solids - 0.03 kg/kkg (0.03 lb/1000 Ib)
anhydrous product
Surfactant - 0.30 kg/kkg (0.30 lb/1000 Ib) anhydrous
product
Oil and Grease - 0.05 kg/kkg (0.05 lb/1000 Ib) anhydrous
product
pH 6.0 - 9.0
136
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Best Practicable control Technology Current.lv Available
This process -too has received much research and development
attention leaving little to be expected in the short term in the
form of process improvement.
In-plant practices can significantly aid in reducing raw waste
loads by handling much of the cleanup dry, or blending off the
material into industrial cleaners, provided the firm is
sufficiently integrated.
Rationale and Assumptions
In small plants particularly, there must be accommodation made
for the disposal of these rather minimal wastes, in that the off
specification product could seriously impact the product quality
if incorporated in that stream.
The raw waste loading has been structured higher than that for
oleum sulfonation to acknowledge the product degradation which
takes place when sulfonated material remains in the reaction
area, requiring thorough washouts.
203 - SQ3 SOLVENT ANP_yA.CUUM.SULFONATION
General
Other than an occasional washout, this process is essentially
free of waste water generation.
Raw Waste Loading
The following raw waste loading is expected:
BOD5 - 3 kg/kkg (3 lb/1000 Ib) anhydrous product
COD - 9 kg/kkg (9 lb/1000 Ib) anhydrous product
Suspended Solids - 0.3 kg/kkg (0.30 lb/1000 Ib)
anhydrous product
Surfactant - 3 kg/kkg (3 lb/1000 Ib) anhydrous
product
Oil and Grease - 0.5 kg/kkg (0.5 lb/1000 Ib) anhydrous
product
Best^ Practicable Control._Technology Currently Available Guidelines
On a thirty day average basis, the following parameter levels are
recommended:
BOD5 - 0.30 kg/kkg (0.30 lb/1000 Ib) anhydrous product
137
-------
COD - 1.35 kg/kkg (1.35 lb/1000 Ib) anhydrous product
Suspended Solids - 0.03 kg/kkg (0.03 lb/1000 Ib)
anhydrous product
Surfactant - 0.30 kg/kkg (0.30 lbs/1000 Ibs) anhydrous
product
Oil and Grease - 0.05 kg/kkg (0.05 lb/1000 Ib) anhydrous
product
pH 6.0 - 9.0
No additional allowance above that for variability of treatment need be
made for startup, shutdown
or upset conditions.
Best^Practicable Control Technology Currently Available
Secondary biological treatment will adequately handle the
wastes from this process.
Rationale
As in other categories, there will be some occasions when
washouts will be required.
20t - SULFAMIC^ACID SULFATION
General
Washouts are the only waste water effluents from this pro-
cess.
Raw Waste Loading
The following raw waste loading is expected:
BOD5 - 3 kg/kkg (3 lb/1000 Ib) anhydrous product
COD - 9 kg/kkg (9 lb/1000 Ib) anhydrous product
Suspended Solids - 0.3 kg/kkg (0.3 lb/1000 Ib)
anhydrous product
Surfactant - 3 kg/kkg (3 lb/1000 Ib) anhydrous
product
Oil and Grease - 0.5 kg/kkg (0.5 lb/1000 Ib) anhy-
drous product
138
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Best Practicable Control Technology Currently Available
Guidelines "
On a thirty day average basis, the following parameter levels are
recommended:
BOD5 - 0.3 kg/kkg (0.3 lb/1000 Ib) anhydrous pro-
~~ duct
COD - 1.35 kg/kkg (1.35 lb/1000 Ib) anhydrous product
Suspended Solids - 0.03 kg/kkg (0.03 lb/1000 ib)
anhydrous product
Surfactant - 0.3 kg/kkg (0.3 lb/1000 Ib) anhydrous
product
Oil and Grease - 0.05 kg/kkg (0.05 lb/1000 Ib) anhy-
drous product
pH 6.0-9.0
No startup, shutdown or upset allowance is recommended.
Best Practicable Control Technology Currently Available
In order to comply with these guidelines the operator would be
obliged to recycle the most wash water rather than sewer it.
Rationale
This reaction is normally carried out in batches. Reasonable
housekeeping would permit the recycle via a holding tank for most
of the washwater. As in other processes, this one can either
accumulate unusable amounts of dilute washwater or occasionally
have off-specification material to be disposed of. Unlike a
large integrated plant, the.firm using this process is unlikely
to have any alternative other than disposal.
205 - CHLOROSULFONIC ACID SULFATION
General
This specialized process is another route to a high quality
surfactant produced uniquely under mild reaction conditions. The
by-product HCl is a significant distinction from other
sulfcnation processes. It is usually scrubbed out in a caustic
solution with the formation of salt or dissolved in water for
sale as muriatic acid.
Raw Waste Loading
The following values can be expected on a thirty day basis:
139
-------
BOD5 - 3 kg/kkg (3 lb/1000 Ib) anhydrous product
COD - 9 kg/kkg (9 lb/1000 Ib) anhydrous product
Suspended Solids - 0.3 kg/kkg (0.3 lb/1000 Ib)
anhydrous product
Surfactant - 3 kg/kkg (3 lb/1000 Ib) anhydrous pro-
duct
Oil and Grease - 0.5 kg/kkg (0.5 lb/1000 Ib) anhydrous
product
Best Practicable Control Technology Currently Available Guidelines
As a thirty day average the following parameter levels are
recommended:
BOD5 - 0.3 kg/kkg (0.3 lb/1000 Ib) anhydrous product
COD - 1.35 kg/kkg (1.35 lb/1000 Ib) anhydrous product
Suspended Solids - 0.03 kg/kkg (0.03 lb/1000 Ib)
anhydrous product
Surfactant - 0.30 kg/kkg (0.30 lb/1000 Ib) anhydrous
product
Oil and Grease - 0.05 kg/kkg (0.05 lb/1000 Ib) anhy-
drous product
pH 6.0 - 9.0
No upsets, startup or shutdown allowances are recommended.
Best mPracticable Control TechnologY^Currently Available
This important, moderately used process is optimized to the
extent reasonably expected.
The effluent washouts are minimal and the required loadings
reasonable in relationship to the other processes. Recycling
washouts can materially aid in meeting these guidelines.
Biological secondary treatment is adequate to handle the expected
raw waste load.
206 - NEUTRALIZATION OF SULFURIC ACID ESTERS AND SULFQNIC ACIDS
General
Neutralization is the essential step which converts the sulfonic
acids or sulfuric acid esters into neutral surfactants. It is a
140
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potential source of some oil and grease generation due to the
possible hydrolysis of the sulfates. Occasional leaks and spills
around the pump, valves, etc., are the only expected source of
waste water contamination.
Raw Waste Loading
The following loadings can be expected:
BOD§ - 0.10 kg/kkg (0.10 lb/1000 lb) anhydrous product
COD - 0.3 kg/kkg (0.3 lb/1000 lb) anhydrous product
Suspended Solids - 0.3 kg/kkg (0.3 lb/1000 lb) anhy-
drous product
Surfactant - 0.2 kg/kkg (0.2 lb/1000 lb) anhydrous
product
Oil and Grease - 0.1 kg/kkg (0.1 lb/1000 lb) anhydrous
product
Best_Practicable Control Technology Currently Available Guidelines
On a thirty day average basis the following parameter values are
recommended:
BOD5 - 0.01 kg/kkg (0.01 lb/1000 lb) anhydrous product
COD - 0.05 kg/kkg (0.05 lb/1000 lb) anhydrous product
Suspended Solids - 0.03 kg/kkg (0.03 lb/1000 lb) anhy-
drous product
Surfactant - 0.02 kg/kkg (0.02 lb/1000 lb) anhydrous
product
Oil and Grease - 0.01 kg/kkg (0.01 lb/1000 lb) anhydrous
product
pH 6.0 - 9.0
No startup, shutdown or upset allowances are recommended.
Best Practicable Control Technology Currently Available
This process step is quite simple and usually continuous when in
tandem with a continuous sulfonator. The biotreater in secondary
treatment processing can accommodate the load. Recycle is
probably the best way to eliminate waste loads.
Rationale
141
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In a large volume operation of this type there will be occasional
inadvertent leaks of valve and pump packing, spills due to
maintenance disruption of piping, and occasional cleanup to
repair the equipment, all necessitating the generation of dilute
waste water streams. These streams are usually too dilute for
recycle back into the process, but by use of small amounts of
water, recyle is practical. By storage and recycle some of this
washout water could diminish the problem and lead to product
recovery later in the finishing process.
207 — SPRAY DRIED DETERGENTS
General
This unit operation is one of the most critical - and the largest
- as well as the most important of the detergent industry. Here,
the final detergent particles are formed which must have the
appropriate physical characteristics for solubility, packaging
and storage.
Tower cleanliness is essential so that degradation products or
material significantly different made in an earlier run do not
contaminate the currently processed product. In such a case, the
spray tower is put through a multi-stage, thorough cleaning
process.
After the large dry "chunks" of adhering detergent are knocked
down by hand, the tower walls are abraded. Finally, water is
played over the surface to finish the cleaning process. The
frequency of tower "turnaround" varies considerably in practice.
Some towers operate for many weeks before shutdown and washing.
Others may have a tower changeover sixteen times in a given
month. In many cases there are product changeovers made on-the-
fly requiring neither stoppage of spray tower operation nor
cleanout.
Among many of the towers which have extended runs on one product,
there is minimal discharge as waste water effluent. All of the
dry product is recycled or sent to solid waste disposal. The
washwater and scrubber water is all sent back into the process
and recycled to extinction.
There are numerous possible sources of water containing
contaminants originating in this process. They encompass
crutcher cleanouts, packaging equipment cleanouts, storage area
washouts, vent scrubbers, etc.
Characteristics of the exit air coming out of the spray tower are
largely determined by the composition of the detergent
formulation being dried. The increasing use of alcohol sulfates
and ethoxylated alcohols as active ingredients has increased
plume generation in this air stream which is not effectively
eliminated by mechanical and electrostatic methods, thus
142
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resulting in a significant volume of scrubber water being
employed.
The total volume of scrubber water and washouts becomes too great
to te recycled to extinction in some spray tower operations when
they have to meet source air standards. Consequently, some waste
water is expected to be sent to the sewer under these conditions.
A similar problem is faced by those who operate spray towers on a
fast turnaround basis. They end up with much more washout waste
water than they can handle via recycle.
In both cases cited above, the other immediately apparent al-
ternative is to reuse all of the water, forcing the solids
concentration of the tower slurry from around 70 percent to some
lower value. This is not a suitable alternative, particularly
from an environmental viewpoint, since excessive energy
consumption would be required to drive off the additional water.
Raw Haste Loading
Under normal spray tower operation, a thirty day average raw
waste loading can be expected to reach:
BOD5 - 0.1 kg/kkg (0.1 lb/1000 Ib) anhydrous product
COD - 0.3 kg/kkg (0.3 lb/1000 Ib) anhydrous product
Suspended Solids - 0.1 kg/kkg (0.1 lb/1000 Ib) anhy-
drous product
Surfactant - 0.2 kg/kkg (0.2 lb/1000 Ib) anhydrous product
In towers facing particularly stringent air quality problems, the
following waste water loadings can be expected:
BOD5. - 0.8 kg/kkg (0.8 lb/1000 Ib) anhydrous product
COD~- 2.5 kg/kkg (2.5 lb/1000 Ib) anhydrous product
Suspended solids - 1.0 kg/kkg (1.0 lb/1000 Ib) anhy-
drous product
Surfactant - 1.5 kg/kkg (1.5 lb/1000 Ib) anhydrous
product
Oil and Grease - 0.3 kg/kkg (0.3 lb/1000 Ib) anhydrous
product
In spray towers having fast turnarounds (more than 6 per month),
for each added turnaround, the following additional waste water
loadings can be expected:
BOD5 - 2.0 kg/kkg (2.0 lb/1000 Ib) anhydrous product
143
-------
COD - 6.0 kg/kkg (6.0 lb/1000 Ib) anhydrous product
Suspended Solids - 2.0 kg/kkg (2.0 lb/1000 Ib) anhydrous
product
Surfactant - 4.0 kg/kkg (1.0 lb/1000 Ib) anhydrous
product
Oil and Grease - 0.3 kg/kkg (0.3 lb/1000 Ib) anhydrous
product
Best_Practicable Control Technology Currently Available Guidelines
For normal spray tower operation the following thirty day average
parameter values are recommended:
BOD5 - 0.01 kg/kkg (0.01 lb/1000 Ib) anhydrous product
COD - 0.05 kg/kkg (0.05 lb/1000 Ib) anhydrous product
Suspended Solids - 0.01 kg/kkg (0.01 lb/1000 Ib) anhy-
drous product
Surfactant - 0.02 kg/kkg (0.02 lb/1000 Ib) anhydrous
product
pH - 6.0 - 9.0
No special startup, shutdown or upset allowances are recommended.
For spray towers operating under stringent air quality problems,
the thirty day average parameter loading guideline
recommendations are:
BOD5 - 0.08 kg /kkg (0.08 lb/1000 Ib) anhydrous product
COD - 0.37 kg /kkg (0.37 lb/1000 Ib) anhydrous product
Suspended Solids - 0.10 kg /kkg (0.10 lb/1000 Ib) an-
hydrous product
Surfactant - 0.15 kg/kkg (0.15 lb/1000 Ib) anhydrous
product
Oil and Grease - 0.03 kg/kkg (0.03 lb/1000 Ib) anhy-
drous product
pH - 6.0 - 9.0
For spray tower operation with fast turnaround, the following
additional allowance should be made for each turnaround above 6
per month:
BOD5 - 0.02 kg/kkg (0.02 lb/1000 Ib) anhydrous product
144
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COD - 0.09 kg/kkg (0.09 lb/1000 Ib) anhydrous product
Suspended Solids - 0.02 kg/kkg (0.02 lb/1000 Ib) an-
hydrous product
Surfactant - 0.04 kg/kkg (O.OU lb/1000 Ib) anhydrous
product
Oil and Grease - no additional allowance
pH - 6.0 - 9.0
This is in essence an upset allowance for shutdown and startup.
No other special upset allowances are recommended for spray tower
operations in general.
Best Practicable_Control Technology Currently Available
It is expected that the levels of effluent constituents can be
met readily if the equivalent of cyclone scrubbers are used
before electrostatic precipitators in the air stream exiting from
the spray tower. Since the function of the water scrubbing is to
chill the air as well as remove particulate matter, a significant
step toward reduced effluent loading can be taken by substituting
cooled recycle water for that used on a once through basis.
With the water recycled, a sufficient concentration can be built
up in the water flow to make return to the detergent making
process possible. Foaming is avoided by maintaining the
surfactant concentration at a sufficiently high level in the
recycled scrubber water. Though only a possible option for best
practicable technology, this approach should be seriously
considered for best available technology.
Ultimately, the secondary biotreater will have no difficulty
processing the waste load from the spray tower area.
Rationale
The demands for clean air and clean water come into conflict in
spray tower operation. In order to meet the increasingly tighter
air pollution regulations while producing products which are more
environmentally compatible, tower operation problems develop.
These newer formulations contain increasing amounts of nonionic
surfactants which are prone to produce an aerosol plume that
persists in the exit tower gas.
A system of dry cyclone dust collectors followed by an
electrostatic precipitator is suitable for removing the
particulate matter present, but it does not influence the plume
since it is a vapor.
145
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By inserting a wet scrubber in between the cyclone dust collector
and the electrostatic precipitator the particulate matter is
further reduced and the organic aerosol vapors are condensed so
that they can then be removed by the electrostatic precipitator.
Introduction of this scrubber water flow now converts a potential
air contamination into a waste water problem. Since the
materials removed in the scrubber are biodegradable and
essentially the same product as that which is put into our
sanitary sewers throughout the country, this is a satisfactory
method of minimizing the environmental impact.
Additional study is needed in this area, particularly concerning
the economics of installing sufficient tankage to enable the fast
turnaround towers to approach total recycle.
208 — LIQUID DETERGENT MANUFACTURE
General
There are numerous liquid detergent products made and it is
likely that they are going to become more abundant as more
emphasis is placed upon nonphosphate products. Many products,
including heavy-duty detergents, are more amenable to convenient
use and manufacture in the liquid form than as a dry powder.
The term "liquid detergents" embraces a large variety of
formulations which fulfill an equally large spectrum of uses.
The ingredients used to formulate the products have a wide
response to such tests as BOD5. Consequently, the statement of
any single raw waste loading could cause a significant problem to
a given manufacturer.
In the process of preparing the liquid detergent, there are two
main sources of waste water effluent, mixing equipment and
distribution system washouts and filling equipment cleanup. Most
operators recycle as much diluted product as possible, but, as in
the case of spray tower operation, the total water volume cannot
be economically recycled to extinction.
Raw Waste Loading
On a thirty day average basis, the following raw waste loadings
will be experienced:
BOD5 - 2 kg/kkg (2 lb/1000 Ib) anhydrous product
COD - 4 kg/kkg (U lb/1000 Ib) anhydrous product
Surfactant - 1.3 kg/kkg (1.3 lb/1000 Ib) anhydrous product
However, when observing smaller firms, the raw waste loadings may
get to:
146
-------
BOD5 - 5 kg/kkg (5 lb/1000 Ib) anhydrous product
COD - 7 kg/kkg (7 lb/1000 Ib) anhydrous product
Surfactant - 3.3 kg/kkg (3.3 lb/1000 Ib) anhydrous
product
This latter case is associated with the high use of common
transfer lines for moving the product to filling lines, losses
resulting from breaking hose connections and relatively short
filling runs.
Best Practicable Control Technology Currently Available Guidelines
On a thirty day average basis, the following parameter levels are
recommended:
BOD5 - 0.2 kg/kkg (0.2 lb/1000 Ib) anhydrous product
COD - 0.6 kg/kkg (0.6 lb/1000 Ib) anhydrous product
Surfactant - 0.13 kg/kkg (0.13 lb/1000 Ib) anhy-
drous product
pH - 6.0 - 9.0
There should be some accommodations made for the smaller operator
where his loadings are marginally greater than those shown.
Basically, this accommodation should be in the nature of an
allowance for the number of product changes requiring complete
purging and cleaning of filling lines. Another exception which
should be noted is that the COD/BOD^ ratio may rise to 5:1 or
more due to the use of some relatively bio-hard industrial
cleaner ingredients such as orthodichlorobenzene, hydrochloric
acid, or chromic acid, such compounds can upset the biota in
BOD5 tests, as well as giving a refractory residue. No allowance
need be made for the suspended solids or oil and grease since the
products marketed are normally clear, filtered fluids, devoid of
suspended particles.
Best Practicable Control Technology Currently Available
Secondary biological treatment will adequately handle the waste
water effluents from this process if good in-plant control is
practiced to limit the amount of refractory materials.
Rationale
With an industry very much aware of market demands, there will be
a continually changing array of formulations to meet new consumer
preferences and environmental performance demands. There are
generally two different markets for liquid detergents; household
and industrial. In this latter market, many moderately sized
operators supply a wide variety of special purpose detergents to
147
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meet very specialized needs. Often fairly "exotic" materials are
used.
Relatively small operators do not have the flexibility of
operation of the large manufacturers. This, coupled with
numerous small batches of product, creates special waste water
problems, since there is no place to hold or recycle numerous,
varied spills, leaks and washouts associated with the automated
filling lines. The cut-off point in allowances becomes critical,
then, since it could have severe economic consequences for some
manufacturers. There are other special problems relating to
analytical results of effluent evaluations. Due to the wide
variety of products used in liquid formulations, fully acclimated
cultures may not be available for gaining results which reflect
the actual technical conditions.
209 - DRY DETERGENT BLENDING
General
Many different dry detergent blends are made for a multiplicity
of industrial uses. The product is usually marketed in drums.
The customary practice is for many successive batches to be made
in a given mixer before a wet washdown is required.
Raw Waste Loading
An average thirty day waste water loading would be:
BOD5 - 0.1 kg/kkg (0.1 lb/1000 Ib) anhydrous pro-
~~ duct
Suspended Solids - 0.1 kg/kkg (0.1 lb/1000 Ibs) anhydrous product
COD - 0.5 kg/kkg (0.5 lb/1000 Ib) anhydrous product
Surfactant - 0.1 kg/kkg (0.1 lb/1000 Ib) anhydrous product
Best Practicable Control^Technology Currently^Available Guidelines
Based upon a thirty day average, the recommendations of parameter
loadings are:
BOD5 - 0.01 kg/kkg (0,01 lb/1000 Ib) anhydrous pro-
duct
COD - 0.08 kg/kkg (0.08 lb/1000 Ib) anhydrous pro-
duct
Suspended Solids - 0.01 kg/kkg (0.01 lb/1000 Ib)
anhydrous product
148
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Surfactant - 0.01 kg/kkg (0.01 lb/1000 Ib) anhy-
drous product
pH - 6.0 - 9.0
No additional allowance need be made for startup, shutdown, or
upsets.
Best Practicable Control Technology Currently Available
Biological secondary treatment is adequate for the effluent
involved.
Rationale
A wide variety of materials are formulated dry. Although little
water is used, that which is required for the infrequent washings
is critical. It will be very dilute and diverse in content,
unsuitable for recycling.
210 - DRUM DRIED DETERGENTS
General
This well established process produces no effluent, but some
provision must be made for those periods of mandatory washdown
due to equipment failure or critical formulation change.
Raw Waste Loading
The average raw waste load which could be expected is:
BOD5 - 0.1 kg/kkg (0.1 lb/1000 Ib) anhydrous pro-
duct
COD - 0.3 kg/kkg (0.3 lb/1000 Ib) anhydrous pro-
duct
Suspended Solids - 0.1 kg/kkg (0.1 lb/1000 Ib) anhy-
drous product
Surfactant - 0.1 kg/kkg (0.1 lb/1000 Ib) anhy-
drous product
Oil and Grease - 0.1 kg/kkg (0.1 lb/1000 Ib) an-
hydrous product
Best Practicable Control Technology Currently Available Guidelines
On a thirty day average basis, the following parameter levels are
recommended:
BOD5 - 0.01 kg/kkg (0.01 lb/1000 Ib) anhydrous
149
-------
product
COD - 0.05 kg/kkg (0.05 lb/1000 Ib) anhydrous
product
Suspended Solids - 0.01 kg/kkg (0.01 lb/1000 Ib)
anhydrous product
Surfactant - 0.01 kg/kkg (0.01 lb/1000 Ib) anhy-
drous product
Oil and Grease - 0.01 kg/kkg (0.01 lb/1000 Ib) an-
hydrous product
pH - 6.0 - 9.0
No startup, shutdown or upset allowances are required. Due to
the low values recommended, a total of three times the average
should be allowed over any 2H hour period as long as during any
thirty day period the guidelines are maintained.
Best Practicable_Control Technology Currently Available
secondary biological treatment can adequately handle the
constituents.
Rationale
Even though the process is essentially dry, the slurry pans and
other equipment will require an infrequent but necessary and
thorough washout.
211 - DETERGENT BARS AND_CAKES
General
In the manufacture of detergent bars there is need for meticulous
cleaning of equipment to insure that any product which may have
been degraded due to adhering to hot process equipment is removed
and disposed of.
The approximately 160 million pounds of synthetic toilet bar soap
used in the U.S. is significant, yet modest when compared to the
600 million pounds of "natural" soap used in toilet bars.
Raw Waste Loading
The following raw waste load can be expected:
BOD5 - 7 kg/kkg (7 lb/1000 Ib) anhydrous product
COD - 22 kg/kkg (22 lb/1000 Ib) anhydrous product
Suspended Solids - 2 kg/kkg (2 lb/1000 Ib) anhy-
150
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drous product
Surfactant - 5 kg/kkg (5 lb/1000 Ib) anhydrous
product
Oil and Grease - 0.2 kg/kkg (0.2 lb/1000 Ib) anhy-
drous product
Best Practicable control Technology Currently Available Guidelines
On the basis of a thirty day average, the following parameter
levels are recommended:
BOD5 - 0.7 kg/kkg (0.7 lb/1000 Ib) anhydrous pro-
duct
COD - 3.3 kg/kkg (3.3 lb/1000 Ib) anhydrous product
Suspended Solids - 0.2 kg/kkg (0.2 lb/1000 Ib) an-
hydrous product
Oil and Grease - 0.02 kg/kkg (0.02 lb/1000 Ib) an-
hydrous product
pH - 6 - 9
No additional allowance is recommended for startup, shutdown or
upsets. During any thirty day period an allowance of three times
the average should be allowed over a 24 hour duration, provided
that throughout the entire thirty day period the thirty day
average is not exceeded.
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SECTION X
BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE
Introduction
Best available technology economically achievable is expected to
involve both improvement in the manufacturing process as well as
adoption of the best available treatment technology that is
within reason economically.
Not all of the processes identified in best practicable control
technology currently available are expected to discharge less
effluent by 1983. Several of these processes will have reached
an optimum raw effluent reduction in compliance with the best
practicable control technology currently available, attaining
pollution levels so low that it is not feasible to reflect minor
improvements in reduced guideline values. Only those which are
expected to attain a significantly lower effluent level are
discussed in detail in this section.
Improved end-of-pipe treatment is anticipated for further
reduction of both the level of waste discharge and the variation
of treatment efficiency from one day to the next. In recognition
of the latter, it is recommended that the maximum single day
values not be more than two times the thirty day averages. For
those plants having treatment facilities that attain discharges
consistent with the limitations applicable to the best
practicable control, addition of sand or mixed media filtration
should be considered. Plants with no treatment facilities, or
grossly inadequate facilities, should consider two stage
activated sludge, with one stage of the plug flow type, as a more
cost effective alternative to equalization and single stage
activated sludge.
TABLE 7-1
Best Available Technology Economically Achievable Guidelines Reflecting
No Change From Best Practicable Control Technology Currently Available
Note: All values are reported as thirty day averages in kg/kkg
(lb/1000 Ib) of anhydrous product made in that subcategory. The
pH for all subcategories is the range of 6.0 - 9.0.
BOD5 COD Suspended Oil &
Solids surfactant Grease
Fatty Acid by Fat
Splitting-Hydrogenation
Allowance Only 0.25 0.20 0.20 0.00 0.15
Soap From Fatty Acid
Neutralization 0.01 0.05 0.02 0.00 0.01
153
-------
Soap Flakes and
Powders 0.01 0.05 0.01 0.00 C.C1
Liquid Soaps 0.01 0.05 0.01 0.00 0.01
Oleum Sulfonation/
Sulfation 0.02 0.09 0.03 0.03 0.07
S03 Solvent and
Vacuum Sulfonation 0.10 O.U5 0.01 0.10 0.02
Neutralization of
Acids 0.01 0.05 0.03 0.02 0.01
Detergent Dry
Blending 0.01 0.08 0.01 0.01 0.005
Drum Dried
Detergents 0.01 0.05 0.01 0.01 0.01
TABLE 7-2
Best Available Technology Economically Achievable Guidelines Reflecting
Changes From Best Practicable Control Technology Currently Available
Note: All values are reported as thirty day averages in kg/kkg
(lb/1000 Ib) of anhydrous product made in that subcategory. The
pH for all subcategories is the range of 6.0 - 9.0.
Batch Kettle Soap
Fatty Acid by
Fat Splitting
Glycerine Concentration 0.40
Glycerine Distillation 0.30
Bar Soaps
Air-SO3 Sulfation/
Sulfonation
Sulfamic Acid
Sulfation
Chlorosulfonic
Acid Sulfation
BOD5
0.40
0.25
0.40
0.30
0.20
0.19
0.10
0.15
COD
1.05
0.90
1.20
0.90
0.60
0.60
O.l»5
0.75
Suspended
.Solids
0.40
0.20
0.10
0.04
0.34
0.02
0.01
0.02
Surfactant
0.0
0.0
0.0
0.0
0.0
0.18
0.10
0.15
Oil 6
Grease
0.05
0.15
0.04
0.02
0.01
0.04
0.02
0.03
154
-------
Spray Dried
Detergents
Normal 0.01 0.08 0.01 O.C2 O.C05
Air Quality
Restricted 0.08 0.35 0.10 0.15 O.C3
Fast
Turnaround 0.02 0.09 0.02 0.03 0.005
Liquid Detergents 0.05 0.23 0.005 0.05 C.OC5
Detergent Bars
and Cakes 0.30 1.35 0.10 0.20 0.02
101 - MODIFIED SOAP MANUFACTURE BY BATCH KETTLE
Best Available Technology Economically Achievable and Rationale
A significant reduction of waste water contamination volume can
be made in the fat pretreatment step of kettle boiling soap
manufacture by replacing the barometric condenser used in vacuum
bleaching by a surface condenser. Such replacement would allow
removal of volatile low molecular weight undesirables from the
effluent. These can be destroyed by burning or perhaps recovered
for sale by refining. This change is shown in Figure 26. An
alternative approach for elimination of the pollutant load
entrained in barometric condensates is use of a liquid film
extraction unit ahead of the barometric condenser as currently
practiced by one company within the industry.
Raw Waste Loading
The expected raw waste load is:
BOD5 - U kg/kkg (« lb/1000 Ib) anhydrous soap
COD - 7 kg/kkg (7 lb/1000 Ib) anhydrous soap
Suspended Solids - H kg/kkg (<* lb/1000 Ib) anhy-
drous soap
Oil and Grease - 0.5 kg/kkg (0.5 lb/1000 Ib) an-
hydrous soap
Best Available Technology Economically Achievable Guidelines
Please refer to guidelines in Table 7-2 at beginning of this Section.
102 - FATTY ACID MANUFACTURE BY FAT SPLITTING
Best Available Technology Economically Achievable and Rationale
Referring to the schematic flow diagram 102, there are two ways
of diminishing further the effluent streams from this unit. The
155
-------
SECTION X
LEVEL II TECHNOLOGY
•
101 - SOAP MANUFACTURE BY BATCH KETTLE : MODIFIED
Wll DECEIVING
STORAGE-TRANSFER
101! FAT REFINING
AND BLEACHING
1013 SOAP BOILING
NEAT SOAP TO
BUNG
AND SALE
GLYCERINE TO
RECOVERY
LOM GRADE SOAP
LOW GRADE
Arrv ACID
FIGURE 26
-------
SECTION X and SECTION XI
LEVEL II TECHNOLOGY
and
LEVEL III TECHNOLOGY
102 Modified: FATTY ACID MANUFACTURE BY FAT SPLITTING
ton RECEIVING
STOflAGE-TRANSFER
102; FATPRETREATMENT
IWASTEWATER I
102X1 I
SOLID WASTE
102209
WASHINGS
W2721
FATTY AGIOS
TO SALES.
NEUTRALIZATION
OR HYDROGENATION
FIGURE 27
-------
SECTION* and XI
LEVEL II TECHNOLOGY
and
LEVEL III TECHNOLOGY
SCHEMATIC - 102-H: FATTY ACIDS MANUFACTURE : HYDROGENATION STEP, IF CARRIED OUT.
RECYCLE -«
TO:
DISTILLATION
OF FATTY ACIDS
in
CD
FATTY ACIDS
FEED TO
HYDROGENATION
FROM:
102-M
CATALYST
BED
OR
SUSPENDED
CATALYST
WITH
TRAYS
COMPRESSOR
FROM
STORAGE
HYDROGENATED
FATTY ACIDS TO:
SALES OR
NEUTRALIZATION
HYDROGENATED
FATTY ACIDS
HYDROGEN:
FROM SUPPLIER
BLEED
IMPURITIES
TO SUPPLIER
OR VENT:
TO STACK
SPENT
CATALYST
AND
POLYMERS
-------
first of these is in-process recycle of the process condensate to
the maximum extent possible. Secondly, the barometric condenser
of the fatty acid distillation process can be replaced with a
surface condenser thereby reducing by approximately 80 percent
the amount of light ends going into the waste water stream during
acid separation and purification. These light ends can be
recovered for sale. The water stream can be then recycled back
into the fat splitting process. The overall process (including
hydrogenation) is shown in Figures 27 and 28. Use of a liquid
film extraction unit ahead of the barometric condenser is also
applicable to this subcategory.
Raw Waste Loadings
The following raw waste loadings can be expected.
BOD5 - 2.5 kg/kkg (2.5 lb/10CO Ib) anhydrous fatty acid
COD - 6.0 kg/kkg (6.0 lb/1000 Ib) anhydrous fatty acid
Suspended Solids - 2.0 kg/kkg (2.0 lb/1000 Ib) anhydrous
fatty acid
Oil and Grease - 1.5 kg/kkg (1.5 lb/1000 Ib) anhydrous
fatty acid
Best Available Technology Economically Achievable Guidelines
Please refer to guidelines in Table 7-2 at beginning of this
Section.
^- GLYCERINE RECOVERY AND CONCENTRATION
Best Available Technology Economically Achievable and Rationale
Replacement of the barometric legs in both the glycerine
concentration and distillation processes would reduce glycerine
losses and waste water loadings substantially. These changes are
shown in Figures 29 and 30.
Raw Waste Load
The following average raw waste load is expected:
Glycerine Concentration
BOD5 - 4.0 kg/kkg (4.0 lb/1000 Ib) anhydrous glycerine
COD - 8.0 kg/kkg (8.0 lb/1000 Ib) anhydrous glycerine
Suspended Solids - 1.0 kg/kkg ( 1.0 lb/1000 Ib) anhydrous
glycerine
Oil and Grease - 0.4 kg/kkg (0.4 lb/1000 Ib) anhydrous
159
-------
104 GLYCERINE RECOVERY
1041 RECEIVING 1042 LYE TREATMENT 'O43 GLYCERINE EVAPORATION TO 80% CONCENTRATION
STORAGE TRANSFER
SOAP MAKING
SOLUTION MAKE UP
80% GLYCERINE TO CONCENTRATOR
HEAVY ENDS TO FOOTS STILL
FIGURE 29
-------
1044 GLYCERINE STILL
104-B: CONCENTRATION OF 80% GLYCERINE TO 99.5%
80%GLYCERINE
from 104 A
HEAVY ENDS
from 104 A
FOOTS TO FLARE
OR WASH TO SEWER
STILL
CHARCOAL
1
1
1
1
1
1 1
• 1 i
GLYCERINE | SOLID WASTE
FOOTS - ,0440s
1O4423 '
FOOTS STILL \
\
COOLING TOWER!
R SLOWDOWN
1
99.5% G
TO SAL
1 ' 1
1st STAGE
SURFACE
CONDENSOR ,
REFINED GLYCERINE ^ Op.iona, ^ 1 ™MOSPHERE
•- CONDENSOR VACUUM
J 1 ' PUMP
Optional )
GCONDENSATE
RECEIVER
LYCERINE U C PUMr
s
Dry C,u»,,c Soda WASH j LIQUID
CAUsTtc BLEED: TO FLARE
""**" SODA
Dry Salt
SALT
1 . F
'• s
, F
HEAVY ENDS TO
FOOTS STJLL
RECYCLE SALT TO:
SOAP MAKING
RECYCLE CAUSTIC
TO: SOAP MAKING
FIGURE 30
-------
glycerine
Glycerine Distillation
BOD5 - 3.0 kg/kkg (3.0 lb/1000 Ib) anhydrous glycerine
COD - 6.0 kg/kkg (6.0 lb/1000 Ib) anhydrous glycerine
Suspended Solids - 0.4 kg/kkg (0.4 lb/1000 Ib) anhydrous
glycerine
Oil and Grease - 0.2 kg/kkg (0.2 lb/1000 Ib) anhydrous
glycerine
Best Available Technology Economically Achievable Guidelines
Please refer to guidelines in Table 7-2 at beginning of this
Section.
PROCESS 106^- BAR.SOAPS
Best Available Technology Economically Achievable and Rationale
By 1983 there is an expectancy that the current relatively high
BOD5 waste load from air scrubbing will be improved to more
closely match those operations which now are experiencing very
low discharge rates. Installation of an atmospheric flash
evaporation unit ahead of the vacuum drying unit, if such is
employed, will materially reduce both carryover and utilities
requirements.
Raw Waste Load
The following average raw waste load is expected:
BOD5 - 2.0 kg /kkg (2.0 lb/1000 Ib) anhydrous soap
COD - 4.0 kg/kkg (4.0 lb/1000 Ib) anhydrous soap
Suspended Solids - 3.4 kg/kkg (3.4 lb/1000 Ib) anhydrous
soap
Oil and Grease - 0.3 kg/kkg (0.3 lb/1000 Ib) anhydrous
Begt Available Technology Economically Achievable Guidelines
Please refer to guidelines in Table 7-2 at beginning of this
Section.
202 - AIR - SO3 SULFATION AND SULFONATION
162
-------
Best Available Technology Economically Achievable Guidelines S Rationale
When vapor phase sulfur trioxide is used in sulfonation and
sulfation processes, regardless of whether or not the vapor S03
is diluted with nitrogen or air, three distinct types of feed and
reactions for the application of sulfur trioxide need to be
considered. The three feed stocks involved are 1) alkyl
benzenes; 2) alpha or branched chain olefins; and 3) lauryl,
fatty and/or ethoxylated alcohols. Please refer to figures 35-
37.
The sulfur trioxide used in these three processes using different
reactants may be prepared in three different ways. Althouth
other methods of preparation are also possible, the following are
those used commercially. The first process for producing sulfur
trioxide is that of sulfur burning. In this process a liquid
sulfur is vaporized and burned, usually in two stages, with air
to form a sulfur trioxide-air mixture which can be fed directly
in vapor form to the sulfonation/sulfation unit.
Another source of sulfur trioxide is that derived from high
strength oleum. In this process, 65-70 percent oleum is the
purchased feed component. It is heated in a reboiler operation
to produce anhydrous vapor S03, as the concentration of the oleum
is reduced to a 20 percent or even a lower level. The SO3 vapor
is then diluted with air or nitrogen as the feed stream to the
reactor. The sulfuric acid remaining is then sold or transferred
to a sulfuric acid manufacturer for reconstitution to the higher
65-70 percent oleum level.
A third way of obtaining sulfur trioxide is by purchasing
stabilized liquid sulfur trioxide. This source of sulfur
trioxide can be brought in by tank cars or by an over- the-fence
arrangement. It is of 99 percent or higher purity and in a
stabilized form of one of its phases. It is stored over an inert
gas, usually nitrogen, in order to preserve its stability in
storage while in the liquid state.
For the purpose of costing, S03 has been assumed to be
manufactured by burning sulfur. It was further assumed that this
does not add to the water effluent waste loading, since most of
the losses from carrying out the preparation of S03 would be in
the vapor phase and therefore concerned only with problems of
waste blowing into the atmosphere, if any.
In a sense, the purchase of sulfur trioxide in its stabilized
form would lead to no different degree of air or water effluent
waste. In the case of sulfur trioxide production from high
concentrations of oleum, then a reboiler reactor, which produces
the SO3 vapor, does lead to a liquid stream of sulfuric acid.
However, as stated earlier, this is generally sent over the fence
or even shipped for reconcentration to the original strength
oleum. It thus presents no added water effluent flow except for
spills and accidental incidents.
163
-------
When an alkyl-benzene is employed as the raw material for
reaction with sulfur trioxide, as well as in the other reactants
mentioned above, there are side reactions which occur if
sufficient heat removal and close temperature control is not
attained. Therefore, generally useful, is the recycle of the
cooled intermediate state alkyl-benzene sulfonic acid or the
alkene sulfonic acid or the lauryl alcohol sulfuric acid back
into the staged reaction loop, after cooling. In this way and
with good temperature control, preferably in the range of 60-80 C
(140-176 °F), high yield of the desired products may be obtained.
In the case of alkyl-benzene as a feed stock, it is desired
principally to obtain the para-substituted product rather than
those in other positions on the benzene ring. If high
temperatures at the surface of contact are unfortunately reached,
there is a strong tendency for both disproportionation and ring
isomerization in the case of alkyl-benzene feed stock. In
addition to the desired mono-substituted alkyl-benzene sulfonic
acid, a fair amount of anhydrides of sulfonic acid are also
obtained. These are essentially the anhydride of two
alkyl-benzene sulfonic acid molecules. These anhydrides must be
hydrated with water or otherwise reacted, in order to produce
alkyl-benzene sulfonic acid of good quality. This reaction to
produce the anhydrides is the result of the affinity for sulfur
trioxide in the liquid phase to react with water, extracting it
from combined hydrogen and hydroxyl groups, to form sulfuric
acid. The sulfuric acid in the water phase cannot be reverted
but must instead be decomposed by the dilution or hydration with
added water in a separate step.
When either an alpha olefin or a branched chain olefin is to be
sulfonated, several side reactions occur which diminish the
product quality and result in by-products which must be dealt
with. The principal reaction besides that of the sulfonation of
the olefin to produce the alkene-sulfonic acid in the terminal
bond position of the olefin, is that of bond migration where the
sulfur trioxide reacts and moves along the chain, so that no
longer does one obtain a terminal sulfonic acid product but one
which is branch chained at the position of the sulfur trioxide
addition.
Another reaction forming undesirable by-products that occurs with
sulfur trioxide and an olefin is that of the formation of
sultones, which are a cyclyzed form of the thiolone. These
appear generally in three of their most stable forms, that is,
alkyl- propane sultone, alkyl-butane sultone and also
octane-alkyl sultone, all of which must first be destroyed before
'a useful product can be obtained.
The conversion of sultones is accomplished by direct reaction
with caustic soda or sodium hydroxide, which produces the sodium
hydroxy-sulfonate of the alkene product together with a sodium
alkene sulfonate in stoichiometric proportions. The normal
reaction product, alkene sulfonic acid, is simultaneously
164
-------
neutralized with caustic soda to form the desired sodium alkene
sulfonate and water.
In the case of sulfation reactions in which an alcohol, an
ethoxylated alcohol or an ethoxylated phenol is used for
sulfation with sulfur trioxide, the product formed is an organic
sulfuric acid. In this case, the same by-products can occur as
with oleum sulfation.
The reaction products from the alpha olefin or branched olefin
must first be neutralized to produce the desired sodium alkene
sulfonates before further hydration, whereas in the case of the
direct reaction of sulfur trioxide with alkyl-benzene, the
neutralization can follow hydration steps. Of course, an organic
sulfuric acid requires no hydration.
In all cases of these three reactions there is usually a holding
tank after a cyclone separation of vapor SQ3 that is unreacted,
and the liquid streams of product and sulfuric acid. For this
reason the holding tank provides not only additional residence
time for the completion of the formation of sulfonic acids or
alkyl alcohol sulfuric acid, but completes the reaction so that a
recycle stream can be returned to the sulfonator or sulfator
stage in order to get increased heat transfer and diminish the
possibility of double substitution of a sulfonic acid group.
Some of these reactions are carried out simultaneously in certain
instances because alkyl benzene sulfonate and the fatty alcohol
sulfates are both often blended for a better balanced detergent.
This blending can best be done after the reaction loop but before
the hydration and neutralization steps, and leads to superior
blended products.
The neutralization of the reaction can be carried out with any
alkaline neutralizing agent depending upon the product desired.
For example, caustic soda, as earlier described, aqua ammonia,
which will lead to the formation of an ammonium salt; potassium,
or even ethanol amines can be used. In addition, when liquid
detergents are being made, substances such as low molecular
weight alcohol, urea, toluene and/or xylene sulfonates for
hydrotropic agents can be also simultaneously made in tandem
operations and blended before hydration and neutralization.
The most feasible means of decreasing water effluent contaminants
and simultaneously of increasing the quality of the product, as
it applies either to a batch or a continuous system assumed in
BPCTCA technology, is the addition of dilution in the reaction
step, increased agitation to diminish temperature elevations as a
result of the exothermal nature of the reaction, or better
contact between the vapor sulfur trioxide and the liquid reactant
phases. Additionally, a batch counter-current process can be
installed by utilizing two or more reaction loops, in which the
fresh sulfonic acid in the form of sulfur trioxide, is introduced
into the stream to the completion stage or holding stage of the
165
-------
reaction in counter- cur rent to the feed of the alkyl- benzene,
the olefin, or a fatty acid alcohol. Such a batch
counter-current arrangement is easily feasible and should be
economically viable by the addition of one or more small reaction
loops for a second and even third stage of the process.
Raw Waste Loadings
The following average raw waste loadings can be expected:
BOD5 - 1.9 kg/kkg (1.9 lb/1000 Ib) anhydrous product
COD - 3.7 kg/kkg (3.7 lb/1000 Ib) anhydrous product
Suspended Solids - 0.2 kg/kkg (0.2 lb/1000 Ib) anhydrous product
Surfactant - 1.8 kg/kkg (1.8 Ib. 1000 Ib) anhydrous product
Oil and Grease - 0.4 kg/kkg (0.4 lb/1000 Ib) anhydrous product
Best Available Technology Economically Achievable Guidelines
Please refer to guidelines in Table 7-2 in this section.
PROCESS 203 - S03 SOLVENT AND VACUUM SULFONATION
PROCESS 204 - SULFAMIC ACID SULFATION
PROCESS 205 - CHLOROSULFONIC ACID SULFATION
Best Available Technology Economically Achievable
Improved process control should reduce the waste loading.
Raw Waste Load
The following average raw waste loads are expected (all values
given in kg/kkg, lb/1000 Ib of product produced) .
BQD5 COD Suspended Surfactant oil &
~~ Grease
203 1.0 3.0 0.1 0.1 0.2
204 1.0 3.0 0.1 0.1 0.2
205 1.5 5.0 0.2 1.5 0.3
Best Available Technology Economically Achievable Guidelines
Please see guidelines in Tables 7-1 and 7-2 at beginning of
Section.
PROCESS 207 - SPRAY DRIED DETERGENTS
166
-------
(AIR QUALITY RESTRICTION OPERATION)
Best Available Technology Economically Achievable and Rationale
As discussed in Section VII, installation of tandem chilled water
scrubbers (one with high and one with low detergent
concentration) to scrub the plume will enable meeting air
pollution restrictions while materially reducing the water
effluent load.
Raw Waste Load
The following average raw waste load is expected:
BOD5 - 0.6 kg/kkg (0.6 lb/1000 Ib) anhydrous product
COD -2.5 kg/kkg (2.5 lb/1000 Ib) anhydrous product
Suspended Solids - 0.7 kg.kkg (0.7 lb/1000 Ib) anhydrous
product
Surfactant - 1.0 kg/kkg (1.0 lb/1000 Ib) anhydrous product
Oil and Grease - 0.2 kg/kkg (0.2 lb/1000 Ib) anhydrous
product
Best Available Technology Economically Achievable Guidelines
Please refer to guidelines in Table 7-2 at beginning of this
Section.
PROCESS 208 - LIQUID DETERGENTS
PROCESS 211 - DETERGENT BARS AND CAKES
Best^Available Technology Economically,Achievable and Rationale
Guidelines recommendations for both processes were reduced on the
basis of expected greater control over product losses in washups
and general manufacturing, including employment of technology
covered under Bar soaps.
Raw Waste Load
The following raw waste loads are expected (all values given in
kg/kkg, lb/1000 Ib of anhydrous product.)
BOD5 COD Suspended Surfactant Oil.6
Solids Grease
208 0.5 1.5 0.5
211 3.0 9.0 1.0 2.0 0.2
167
-------
Best Available Technology Economicallv Achievable Guidelines
Please refer to guidelines in the Table 7-2 at the beginning of this
section.
168
-------
SECTION XI
NEW SOURCE PERFORMANCE STANDARDS
AND PRETREATMENT STANDARDS
Introduction
New source performance standards (NSPS), being that which would
be employed in a new source of manufacture, offers an opportunity
to start afresh in the design of production facilities.
Reviewing candidate processes for minimized effluents has
produced no great surprises. Soap and detergent making is a well
established art. Still, a number of relevant, substantive
concepts for improvement have emerged as well as a few fairly far
from commercial realization. Bearing in mind the necessity of
being very practical, in the discussion of all newer developments
for NSPS, particular note has been made of the degree to which
each technique has been reduced to acceptable commercial
practice. The technology, in most categories, reflects the
improvements developed in best available technology economically
achievable. The guidelines for many of these subcategories will
be the same for the two groups of technology. To simplify study
of the recommendations, the guidelines are reported in tabular
form with the processes given new limitations and special
consideration in the text noted by an asterisk. The sign a) in
the table indicates that the 1983 and new source guidelines are
identical. Please refer to the corresponding guidelines
discussion in SECTION X for extensions and exceptions recommended
for the guidelines. These exceptions are applicable to both sets
of guidelines.
Following the discussion of specific process improvements for new
source performance standards is a review of process chemistry
developments which deserve further continuing study for ultimate
improvements in low effluent level products. As with all such
"far out" developments, some of the concepts have greater
probability for success than others. They are offered for the
different perspectives they offer to this sophisticated art of
soap and detergent manufacturing and formulating.
169
-------
TABLE 8
New Source Performance Standards^Guidelines
Note: All values reported are in kg/kkg (lb/1000 Ib) of
anhydrous product made in that category. For all categories the
guidelines pH is 6 - 9.
Suspended Oil 6
BODJ5 COD Solids Surfactant Grease
Batch Kettle and
Continous Soapa 0.40 1.05 0.40 — 0.05
Fatty Acid By Fat
Splitting® 0.25 0.90 0.20 — 0.15
Soap From Fatty
Acid Neutrali-
zations 0.01 0.05 0.02 — O.C1
Glycerine Recovery
Concentration® 0.40 1.20 0.10 -- 0.04
Distillationa 0.30 0.90 0.04 — 0.02
Soap Flakes And
Powders® 0.01 0.05 0.01 — 0.01
Bar Soaps® 0.20 0.60 0.34 — 0,03
Liquid Soapa 0.01 0.05 0.01 — 0.01
Oleum Sulfation/
Sulfonation* 0.01 0.03 0.02 0.01 C.04
Air-SO3 Sulfa-
tion/Sulfonation* 0.09 0.40 0.09 0.09 C.02
SO3. Solvent and
Vacuum Sulfona-
tiono) 0.10 0.45 0.01 0.10 0.02
Sulfamic Acid
Sulfationa 0.10 0.45 0.01 0.10 0.02
Chlorosulfonic
Acid Sulfationa 0.15 0.75 0.02 0.15 0.03
Neutralization
Of Acidsa 0.01 0.05 O.C3 0.02 0.01
Spray Dried
Detergents
Normal® 0.01 0.08 0.01 0.02 0.005
Air Quality
Restricted® 0.08 0.35 0.10 0.15 0.03
Fast
Turnaround® 0.02 0.09 0.02 0.03 0.005
Liquid Deter-
gents® 0.05 0.23 0.005 0.05 0.005
Detergent Dry
Blendinga 0.01 0.08 0.01 O.C1 0.005
Drum Dried
Detergents® 0.01 0.05 0.01 O.C1 0.01
Detergent Bars
and Cakes® 0.30 1.35 0.10 0.20 0.02
-------
PROCESS DISCUSSION
SOAP MANUFACTURE_BY_BATCH_KETTLE
Soap Manufacture lay Continuous Counter-Current^Process
There appears to be little economic driving force for the
construction of a totally new batch soap manufacturing
installation, from fats and oils, in the United States in the
foreseeable future. There will be replacement of some pieces of
equipment as maintenance demands. Soap use is expected to hold
constant at best. Particularly in toilet bars, there is
continuing loss of soap volume to synthetic detergent bars where
the hard water problems are severe.
A totally new installation, starting with fats and oils, will
most likely be a continuous manufacturing process. Although
initial capital investment and operating costs are the lowest
attainable, use of a continuous unit entails the sacrifice of
some manufacturing flexibility. For example, changeovers are
accomplished more conveniently and/or economically with a batch
kettle when it is desired to make a number of different base
soaps, each of which requires different fatty raw materials
input.
Technically, a continuous unit possesses two major advantages.
It uses very little water, thus minimizing the problem of waste
water disposal. Secondly, as the nigre is formed entirely in a
solid state, its handling is greatly simplified. In areas where
there is little or no market for the dark soaps derived from
nigre, this is a distinct advantage. Please refer to Figure 33
for process details.
Manufacturing operations still require preliminary fat refining
and bleaching, as shown in section 1012 of the schematic diagram
for soap manufacture by batch kettle. Therefore, the waste
streams from this process can be minimized only to the extent
described in best available technology economically achievable.
The volume of waste water currently generated by the batch kettle
process can be reduced about 80 percent. Utilities are expected
to run no more than 0.4U0 to 0.660/kkg (0.20 to 0.30/1000 Ib) of
neat soap. Electricity use is somewhat increased by the
requirements of the turbo-disperser motors and those for the
centrifuge operations. This added cost would be. approximately
0.220/kkg (0.10/1000 Ib) of soap product according to best
estimates.
A significant reduction in operating cost would be expected in
the substitution of the continuous processing for a batch kettle
from reduced labor requirements. Instead of labor in the range
of eight to ten men per shift for a kettle plant of circa 9 to
13.6 M kg (20 to 30 M Ib) capacity per year or higher, it should
171
-------
be no more than two or possibly three men per shift for a
continuous unit, representing a striking reduction in labor
costs. Through labor savings alone, capital investment for a
continuous soap process should be recovered within ten years.
Realizing that improvements in the clay treatment and vacuum
bleaching of the feed oils and fats are limited to the
replacement of a barometric condenser by a two-stage surface
condenser, and that only good operating cleanliness can further
reduce the raw waste load, the best available demonstrated
control technology guidelines consider a small allowance for
wastes from fats and oils pretreatment but essentially none for
the continuous saponification process.
By the use of centrifugation, the soaps or fats can be
effectively separated from the salt and lye. Thus, all of these
materials can be reprocessed and it would appear that recommended
guideline levels that could easily be met in the continuous
saponification plant are: BODS, 0.20 kg/kkg; COD, 0.60 kg/kkg;
suspended 'solids, 0.20 kg/kkg; and oil and grease, 0.05 kg/kkg.
Raw Waste Load
The following average raw waste load can be expected:
BOD5 - 2 kg/kkg (2 lb/1000 Ib) anhydrous soap
COD - 4 kg/kkg (4 lb/1000 Ib) anhydrous soap
Suspended Solids - 2 kg/kkg (2 lb/1000 Ib) anhydrous soap
Oil and Grease - 0.5 kg/kkg (0.5 lb/1000 Ib) anhydrous soap
SOAP FROM FATTY ACID NEUTRALIZATION
General
In BADTC technology the manufacture of soap by fatty acid
neutralization is regarded as the norm for the preparation of
neat soap. It is depicted in Figure 3U. Data reported here is a
combination of field visits and contractor's engineering design
parameters. Data from two installations has been integrated with
additional information found in the literature.
BADTC Technology - Soap Manufacture
The continuous process makes use of proportioning pumps with
interlocks and main control-interlocks for absolute rate of feeds
flow, very similar to that outlined in the continuous
saponification process. In this process turbodispersers are used
which greatly enhance the contacting efficiency between the water
and fatty acid or oil phases of the reactants. The reaction time
is reduced to a matter of 10 to 15 minutes total within the
reactor and separation systems.
172
-------
The quality of product made from such a continuous operation is
equivalent to or improved over that from the batch kettle. For
example, the batch kettle process will result in an average
content of free alkali, measured as Na20, of 0.5 percent to 0.75
percent. In the case of the continuous manufacturing operation
(representing an average range of all contractors' claims) the
free alkali is reduced tenfold to approximately 0.05 percent to
0.075 percent. Similarly, the salt content is reduced from 1
percent to 0.5 percent. The neat soap produced from this
reaction needs to be dried from approximately 35 percent water
content to the desired level. The drying process is considered
separately.
Battery limit capital investment, including appropriate tankage
for the reactants, will cost approximately $500,000 for a 20
million pound per year plant. Direct operating labor will
approximate $60,000 per year using standard labor costs.
Appropriate maintenance and administration costs would equal the
direct labor costs. It is estimated that steam consumption will
amount to approximately $6,000 per year; electricity
approximately $10,000 per year, and cooling water approximately
$2,000 per year for a, 20 million pound per year installation. It
must be emphasized that this covers only the neutralization step
for production of neat soap from fatty acids.
BAR SOAP - DRYING
The drying operation is no different than that in BATEA
guidelines for solid bar soap manufacture. A surface condenser
is indicated for use in place of the normal barometric condenser
now generally utilized for soap drying, especially when vacuum
drying operations are carried out for clear soaps.
The capital cost for the above drying operation (for the
production of a bar soap extrudate) is estimated at $200,000 for
9 M kg (20 M Ib) per year of anhydrous soap capacity. Operating
steam, electric and cooling water costs are the same as those
shown for best available technology economically achievable.
SOLVENT PROCESS FOR SOAP MANUFACTURE
A process developed in the 1940's requires no water to make
anhydrous soap and dynamite glycerine.
In the Kokatnur process fats or oils dissolved in heated kerosene
(260-290C) (500-554F) are mixed under pressure with anhydrous
caustic soda. The reaction takes place in ten minutes and
produces dynamite grade glycerine. After drawing off the
glycerine, the remaining mixture is released into an expansion
chamber where evaporation of the kerosene yields anhydrous soap.
The process has the following advantages:
1. Very short reaction time.
173
-------
2. Use of kerosene prevents charring.
3. Absence of water reduces heat requirement.
U. Dynamite grade glycerine and anhydrous soap are obtained directly.
One major defect of the process is that there is no refining
stage and traces of kerosene are left in the soap, making it
impossible to market the product for toilet bar use. without
further refinement the soap is suitable only for limited
industrial uses.
201!..r_-QLEUM SyLFATION^AND_SULFONATION
Extensive contractor data indicates that, with good engineering
design of the reactor and a minimum residence time prior to
neutralization, the levels proposed for raw waste load can be
readily met by a continuous process plant.
Compared to those for batch or semi-batch reverse feed systems,
capital investments for a continuous process are estimated to be
lower by $66/kkg ($30/1000 Ib) of annual capacity. Operational
savings are possible in the form of reduced labor costs, lower
consumption of utilities, and higher conversion of feedstocks
(0.8 to 1.0 percent) to products.
The continuous process is adaptable to almost any size
installation from 90C thousand kg (2 million Ib) per year upward.
Please refer to Figure 35.
Raw Waste Loadings
The following average raw waste load can be expected:
BODJ5 - 0.1 kg/kkg (0.1 lb/1000 Ib) anhydrous product
COD - 0.2 kg/kkg (0.2 lb/1000 Ib) anhydrous product
Suspended Solids - 0.2 kg/kkg (0.2 lb/100C Ib) anhydrous
product
Surfactant - 0.1 kg/kkg (0.1 lb/1000 Ib) anhydrous product
Oil and Grease - 0.4 kg/kkg (O.U lb/10CO Ib) anhydrous
product
S02_AIR;S03 gULFATIQN_AND^SyLFONATION
BADTC guideline recommendations are based on process chains shown
in Figures 35, 36 and 37. The process chain involves the
reaction, hydration, neutralization and finishing steps for
production of alkylated aromatics.
174
-------
Neutralization
NSPS guideline recommendations are based upon technology
illustrated in Figures 35-37 related earlier, each covering a
separate feed stock, i.e., alkyl aromatics, olefins and alcohols.
The process variations reflect the particular chemical reaction
characteristics of the feed stocks.
In an integrated plant utilizing products containing derivatives
of all three feed stocks, superior blended products can be made
by combining the reaction products after the reaction loop but
prior to the hydration and neutralization steps. This procedure
is particularly applicable to the blends of alkyl benzene
sulfonate with fatty alcohol sulfates.
Performance of a new installation based upon continuous
sulfonation/sulfation is expected to be improved moderately over
already installed batch or batch counter current systems. The
form of sulfur trioxide used will not influence the effluent
water quality.
The cost depicted and guaranteed by a supplier shows utility
demands as follows; electricity 0.9 to 1.1£/kg (0.4 - 0.50/lb) of
active material from the reaction; cooling water requirements of
0.1 - 0.22/kg (0.05 - 0.100/lb) of active product. The initial
capital cost for this installation relates of course to plant
size with economy of scale favoring large plants. For plants in
the size range of 13.6M kg per year (30M Ib per year) of active
ingredient, and based upon a 92 percent stream factor, capital
amounts to $88-110/kkg ($40-50/1000 Ib) annually product
capacity.
Use of stabilized liquid sulfur trioxide is assumed. If sulfur
trioxide is produced by sulfur burning, this is considered to be
a separate unit, and the economics and the justification covered
in the water effluent.
Raw Waste Load
The following raw waste load can be expected:
BOD5 - 0.9 kg/kkg (0.9 lb/1000 Ib) anhydrous product
COD - 2.7 kg/kkg (2.7 lb/1000 Ib) anhydrous product
Suspended Solids - 0.9 kg/kkg (0.9 lb.1000 Ib) anhydrous
product
Surfactant - 0.9 kg/kkg (0.9 lb/1000 Ib) anhydrous product
Oil and Grease - 0.2 kg/kkg (0.2 lb/1000 Ib) anhydrous
product
175
-------
SECTION X and XI
LEVEL II TECHNOLOGY
and
LEVEL III TECHNOLOGY
SCHEMATIC FLOW DIAGRAM - 2O1 and 206
CONTINUOUS DETERGENT SLURRY PROCESSING PLANT
HIGH-ACTIVE ALKYLATE SULFONATION WITH OLEUM : FEED A_
LOWNa2S04 CONTENT
206-A: Neutralization
Modified 201 A: SULFONATION
NEUTRALIZED
DETERGENT
SLURRY
FIGURE
-------
SCHEMATIC FLOW DIAGRAM— 201 MODIFIED
CONTINUOUS DETERGENT SLURRY PROCESSING PLANT
FATTY ALCOHOL SULFATION WITH OLEUM : FEEDS B and C
FATTY ALCOHOL
FROM STORAGE
OLEUM
FROM
STORAGE
PROPORTIONING
PUMP
NEUTRALIZED
DETERGENT
SLURRY
ALKALI
Modified: 201-B and C : SULFATION
201-B and C : NEUTRALIZATION
FIGURE 32
-------
SECTION XI
LEVEL III TECHNOLOGY
108: SOAP MANUFACTURE BY CONTINUOUS SAPONIFICATION
toil RECEIVING
STORAGE-TRANSFER
toil FAT REFINING
AND BLEACHING
3
31 LS
ED
OILS
OILS
IDS
SIM
DFATS
k
^
1ft STAGE
KILL
1 LJ=
TURBO
DISPER
SER
t
SI
G
t
i
2nd STAGE
STRONG
CHANGE
1
TURBO
DISPER
SER
*ENT LVE AND
LVCERINE
;*-
1
>d STAGE
WEAK
CHANGE
L
TUHBO
DISPER
(SEW
_4_
1
*
I
4rt> STAGE
FITTING:
BALANCE
1 ,
-1 ,
CENTRIFUGE |
-»* T0
NEAT SOAP
FROM
REACTION
LEAKS. SPILLS. DRAINS.
CONCKNSATES. STEAM
-------
SECTION XI
LEVEL III TECHNOLOGY
103 Modified: SOAP BY CONTINUOUS FATTY ACID NEUTRALIZATION
FEU RECYCLE I
t_«4_
1 FATTY ACM* -
rvACto
r ;
&. [
n> RECCrVMG
STOHAGf TRAMWE1
INTERLOCKED
rROPORTtONING PUMPS MASTER
A t
puwr
A
-d
r
>]
J-
•|_
—
3 r
•u
b
SEQUENTIAL
-., Ofl _
/ TANDEM
VENT 0««*"0"
M STAGE
REACTION
TOWER
1
rURBO
DISPERSE R
-
PU
^ »
:
•\
!•>
Cvton
O»xid«
«A«
V*M
t
<*>,
SEM-
T^;10" sss«|-
i .1. •
Section 1062-Modified:
NEAT SOAP DRYING: FOR BAR SOAPS
TO
ATMOSPHERE
LIGHT ENDS
RECYCLE OR
FLARE
o
c:
8
u>
-------
SECTION XI
LEVEL III TECHNOLOGY
COMBINED PROCESSES
Modified 202 : SOg - SULFONATION / SULFATION PROCESSES - CONTINUOUS
AND
Modified 206 : NEUTRALIZATION OF SULFONIC OR ALKYL SULFURIC ACID PROCESSES - CONTINUOUS
TO SCRUBBERS
202A and 2O6A : SCHEMATIC FLOW DIAGRAM
Modified ALKYL BENZENE SULFONATION
Reaction: 202 A Section
HI
1-1
o
SULFONATION
DIGESTOR
DIGESTION
HYDRATOR
NEUTRALIZATION: 206 A Section
PRODUCT
-> PUMP
WATER
HYDRATION
CAUSTIC SODA
NEUTRALIZATION
-------
SECTION XI
LEVEL III TECHNOLOGY
SCHEMATIC FLOW DIAGRAM
202 C and 206 C: Modified - Combined
FATTY ALCOHOL SULFATION : WITH SO,
Reaction : 202 C Section
Neutralization : 206-C Section
no FATTY
—• ALCOHOL
S03-AIR
TO SCRUBBER
O
CO
cr>
PRODUCT
-------
SECTION XI
LEVEL III TECHNOLOGY
SCHEMATIC FLOW DIAGRAM - COMBINED 202B and 206B
ALPHA - OLEFIN SULFONATION WITH SO,
Reaction: 202 B Section
Neutralization : 206 B Section
ALPHA
OLEFIN
00
ro
O
I
•> PRODUCT
-------
PRETREATMENT REQUIREMENTS
In this section of the report those pollutants capable of dis-
rupting, or likely to disrupt, the operation of a publicly owned
waste water treatment plant are cited. It should be fully
understood that it is not the intent to provide limits or other
standards which would in effect supplant any sewer use ordinance
developed and now being enforced by a central authority. In
fact, every authority that owns a collection and treatment system
should have an up-to-date sewer use ordinance which would enable
it to regulate the types and quantity of industrial wastes
admitted to its system. The purpose of this section is to point
out possible problem areas and indicate applicable control
measures.
With the exception of dissolved mineral salts there is
essentially no pollutant in the wastes from soap and detergent
manufacturers that cannot be removed at high levels of efficiency
in a central plant.
Fats and Oils
Fats and oils from soap plants are readily degradable. whenever
excessive fats, oils or greases are discharged, or whenever a
safeguard against such a discharge is required, the waste should
be passed through a gravity type separator prior to discharge to
the central system. This type of pretreatment serves to remove
up to 90 percent of the free oils which are the primary source of
problems in both sewers and the treatment plant.
As previously discussed, the well-designed fat trap is similar to
a primary clarifier in a municipal plant. An appropriate size
for a large soap plant would be rated 2078 1/day/l sq m (600
gallons/day/square foot). Residence time should be about 1 hour.
Such a fat trap, with a radial flow to the perimeter discharge
weir and a rotating scraper arm which moves the fat layer in
front of the arm and thence into a well, will do an excellent job
and provide essentially complete removal.
The underflow from such a fat trap will have a high treatable
concentration of biodegradable organics. In one of the soap
plants observed in this study a reserve of the underflow is
retained in tanks to be used as a feed for the biological treater
when only a few units of the plant are operating.
If the pollutant is a low molecular weight mineral solvent which
has a low water solubility the same treatment mechanism can be
employed. The captured material should be burned or processed
for reuse. The non-flotables and the liquid phase should be
passed on to the central treatment plant.
The efficiency of the fat trap must be maintained and routine
inspections should be made by the proper authorities.
183
-------
Fats and Oils - Detergent Plants
Detergent plants will have oil and grease effluents more like the
hydrocarbons encountered in the organic chemical industry;
namely, they will be of fossil or petroleum origin rather than
from natural fats. These hydrocarbons are not as readily
degraded as those originating from the soap plant. The only
analytical method, as described in Standatd Methods, makes no
differentiation between the two types of hydrocarbons. Until
such a test can be devised it would be unfair to set a standard
based on the least degradable product and make the more
degradable product conform to it. Additionally, from am economic
standpoint it is most important to make a differentiation in
treatability. The problem is accentuated in that the industrial
detergents will probably contain more hydrocarbons extracted in
the hexane extractable test that are difficult to degrade than
will the household detergents.
Zinc
Concentrations of zinc which could lead to problems at the
central facility have not been found in the waste water examined
or in the data analyzed. The best information available would
indicate that zinc concentrations of between 5 and 100 mg/1 in
the biological portion of the central plant could slow the rate
of assimilation. Therefore, any concentration of not more that 5
mg/1 would appear to be a satisfactory process effluent level.
The observed values have been less than U mg/1. The relationship
of zinc to the activity of nitrifying bacteria is under study in
EPA. The results could have an effect on this standard.
Should a zinc problem arise, pretreatment employing alkaline
precipitation is the most effective means of reducing zinc levels
to satisfactory concentrations in process effluent. This should
be carried out at pH values between 8.5 and 9.5 in the
coagulation unit and at surface loadings of 1627 1 - 20377 1/sq m
(400-5000 gpd/sq ft) in the sedimentation unit. The sludge
should be dewatered and incinerated or dried prior to disposal as
a solid waste.
Industrial and Institutional Cleaners
A number of soap and detergent manufacturers studied produce
industrial cleaners which contain phosphoric and hydrofluoric
acids; and organics such as chlorinated benzenes. The
implication of the first two substances is clear and whenever
they are used, strict in-house control steps should be excercised
to control their discharge. The problem of chlorinated organic
discharge is potentially more serious. These materials used in
such applications as acid cleaners are moderately to highly toxic
to man and may have a deleterious effect on waste treatment
plants and on receiving waters. It is expected that treatability
of these compounds is being studied by the industries
184
-------
manufacturing them. It is suggested that further definition of
their impact, and discussions of in-house and pretreatment
control measures await the completion of those studies.
Many insitutional cleaners may have biocidal or biostatic
materials incorporated in their formulation, and relatively large
amounts of such materials in a discharge could interfere with
normal operation of biological treatment systems. As in the case
of industrial cleaners, strict in-house control should be
exercised to control discharge of these materials.
Should pretreatment be necessary for industrial and institution
cleaners, it would have to be in the nature of chemical-physical
treatment designed to remove the specific materials involved.
185
-------
-------
SECTION XII
ACKNOWLEDGEMENTS
The Environmental Protection Agency wishes to acknowledge the
contributions to the project by Colin A. Houston 6 Associates,
Inc., Mamaroneck, New York. Messrs. Colin A. Houston, Frederick
C. Herot, Charles H. Daniels and Ms. Susan M. Weisman, with the
able assistance of their consultants Mr. George c. Feighner, Dr.
Allen W. Fleer and Mr. Robert W. Okey, conducted the detailed
technical study and drafted the initial report on which this
document is based.
Because of the wide-ranging scope of the study, there was
occasion to call upon many individuals and organizations for
assistance in the course of bringing it to completion. Many
people, both as individuals and as members of various
organizations, responded with the utmost courtesy and generosity.
We regret that space does not permit their individual citation,
but the debt owed to each and every one of them is gratefully
acknowledged.
Throughout the country, soap, detergent and fatty acid producers,
large and small, graciously assisted in providing process
information and opening up their plants to detailed study and
sampling. Three trade associations performed valuable liaison
functions in making the project a truly cooperative one; the Soap
and Detergent Association, the Chemical Specialties Manufacturers
Association, and the International Sanitary Supply Association.
Special help was received from members of the Environmental
Protection staffs in Regions II, IV, V, VI and VIII. As an
example, Mr. William Cloward, Chief, Industrial Waste section,
Region IV, actively contributed to all stages of the project,
including participation in the in-plant sampling program. Many
of the accomplishments of the sampling program are attributable
to the assistance and analytical support received from .the
laboratory of the Division of Water Pollution Control, Louisiana
Wildlife and Fisheries Commission, Baton Rouge, Louisiana and the
following Environmental Protection Agency laboratories:
Analytical Quality Control Laboratory, Cincinnati, Ohio; Robert
S. Kerr Water Research center, Ada, Oklahoma; and the Regional
Laboratories in Athens, Georgia; Evansville, Indiana; Annapolis,
Maryland and Kansas City, Kansas.
A lasting indebtedness is acknowledged to those in the
Environmental Protection Agency who assisted in the project from
inception of the study through preparation and review of the
report. Especially deserving recognition are: Ms. Jan Beale,
John Ciancia, Ms. Patricia Dugan, Ernst Hall, Ms. Frances
Hansborough, Richard Insinga, Thomas Kopp, Ray McDevitt, Ronald
McSwinney, David Mears, John Riley, Ms. Jaye Swanson and George
Webster.
187
-------
-------
SECTION XIII
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58. Motl, C. W. Sulfonation at Low Pressures Using Undi-
luted Sulfor Trioxide. Procter & Gamble.U.S. Patent
^3,248,413.(1966)
59. Morris, R. L. Process Plant for Sulfation of Alpha
Olefins. Procter & Gamble Company. 07 S~. Patent
3,234,258. (1966)
60. National Technical Advisory Commission. Water Quality
Criteria. Secretary of the Interior, Federal Water
Pollution Control Administration, Washington, D.C.
Government Printing Office. April (1968)
61. Pattison, E. Scott. Fatty Acids and Their Industrial
Application. Marcel Dekker, Inc., New York(1968)
62. Potts, R. H. and Me Bride, G. W. Continuous Hydroly-
sis Process of Colgate - Emery Companies. Chemical
Engineering. (1950)
63. Projected Waste Water Treatment Costs in the Organic
Chemicals Industry (updated).Datagraphics, Inc.,
Pittsburgh, Pennsy1vania. July (1971)
64. Industrial Wastes; Their Disposal and Treatment.
"Rheinhold Publishing Corp., New York.
65. Sharpies Division of Pennwalt company. Sharpies
Continuous Soap Process. Brochure. Pennwalt Company,
Warminster, Pennsylvania. April (1972)
66. Smith, Curtis W. Acrolein: Derivatives of Glyceral-
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67. Tashen, Edward S. and Booman, Keith A. Biodegrada-
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Class of Nonionic Surfactants. Proceedings of the
22nd Industrial Waste Conference.pp 211.Purdue
University, Lafayette, Indiana.(1967)
193
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68. Todd, David Keith. The Water Encyclopedia. Water
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69. Texas Division, The Dow Chemical Company. Treatment
of waste Water from the Production of Polyhydric Organics.
For Office of Research and Monitoring Environmental
Protection Agency. Project no. 12020 EEQ. October
(1971)
70. Tyschbinek, G. Alcohol Esterification with Chloro-
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194
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SECTION XIV
GLOSSARY
ABS - An abbreviation applied to a family of closely related
branched side-chain benzene compounds formerly used as sur-
factants in household detergents. ABS is an acronym for al-
kyl benzene sulfonate.
Act - The Federal Water Pollution Control Act Amendments
of 1972, Public Law 92-500.
Aerobic - Growing only in air or free oxygen.
Aerobic Bacteria - Bacteria which require the presence of
free (dissolved or molecular) oxygen for their metabolic
processes. Oxygen in chemical combination will not support
aerobic organisms.
Alkalinity - A quantitative measure of the capacity of li-
quids or suspensions to neutralize strong acids or to re-
sist the establishment of acidic conditions. Alkalinity
results from the presence of bicarbonates, carbonates,
hydroxides, volatile acids, salts and occasionally borates,
terms of the concentration of calcium carbonate that would
have an equivalent capacity to neutralize strong acids.
Amalgamator - A large horizontal mixer used to blend per-
fume, dyes, fillers (titanium dioxide for whitening), and
other materials in the manufacture of soap.
Anaerobic Bacteria - Bacteria that do not require the pres-
ence of free or dissolved oxygen for metabolism. Strict
anaerobes are hindered or completely blocked by the presence
of dissolved oxygen and in some cases by the presence of
highly oxidized substances such as sodium nitrate, nitrites,
and perhaps sulfates. Facultative anaerobes can be active in
the presence of dissolved oxygen but do not require its
presence, see also aerobic bacteria.
Anaerobic Decomposition - Reduction of the net energy level
and change in chemical composition of organic matter caused
by microorganisms in an anaerobic environment.
Antioxidants - Phenolic and amino compounds which inhibit
oxidation of organic compounds.
Atmosphere - Unit of pressure. One atmosphere is normal
atmosphere pressure.
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Barometric Condenser - A system of both chilling vapors
into the liquid state from a gaseous state and reducing
flowing down a vertical pipe with considerable velocity.
Identical to the laboratory aspirator, which depends upon
the Venturi effect to create a vacuum.
Battery Limits - In considering plant construction and
costs, an arbitrary boundary between essential process
units and supporting facilities. Customarily within bat-
tery limits are reactors, stills, mixers, driers, and
fabricators. Usually outside battery limits are power
plants, cooling towers, sewage and water treatment, raw
material and product storage, laboratory and office buildings
and roads.
Best Available Demonstrated^ Control Technology (BADCTL -
Treatment required for new sources as defined by Section
306 (a) (2) of the Act. Level III.
Treatment required by July 1, 1983 for industrial discharges
to surface waters as defined by Section 301 (b) (2) (A) of
the Act. Level II.
Best Practicable Control Technology Currently Available
(BPCTCA) ~ Treatment required by July 1, 1977 for industrial
discharges to surface waters as defined by Section 301 (b)
(1) (A) of the Act.
Biological Cooling Tower - A cooling tower which is seeded
with microorganisms and fed with nutrients in which biological
degradation of organics occurs.
Biological Oxidation - The process whereby, through the
activity of living organisms in an aerobic environment,
organic matter is converted to more biologically stable
matter.
Biological Stabilization - Reduction in the net energy level
of organic matter as a result of the metabolic activity of
organisms.
Biological Treatment - Organic waste treatment in which bac-
teria and/or biochemical action is intensified under con-
trolled conditions.
Blowing^Tower - See spray tower.
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BOD5 - Biochemical oxygen demand. An indirect measure of the
concentration of biologically degradable material present in
organic wastes. It is the amount of free oxygen utilized by
aerobic organisms when allowed to attack the organic matter
in an aerobically maintained environment at a specified
temperature (20°C) for a specific time period (five days).
It is expressed in milligrams of oxygen utilized per liter
of liquid waste volume (mg/1) or in milligrams of oxygen per
kilogram of solids present (mg/kg=ppm=parts per million parts)
Builders - Inorganic salts (usually) which augment the
cleansing or dirt-suspending power of a soap or detergent;
i.e., sodium silicate, sodium carbonate, carboxy methyl
cellulose, phosphates, etc.
Capital Costs - Financial charges which are computed as the
control. The cost of capital is based upon a weighted aver-
age of the separate costs of debt and equity.
Caustic - Sodium hydroxide, caustic soda.
Changes - Those separate and identifiable steps taken in the
manufacture of kettle boiling soap.
Chemical Oxidation - Oxidation of organic substances without
benefit of livingTorganisms. Examples are by thermal combus-
tion or by oxidizing agents such as chlorine.
Clay - Alumino silicate minerals.
Closed Soap - That single phase of soap and water having a
creamy consistency while in the hot, agitated state.
COD - Chemical Oxygen Demand. An indirect measure of the
biochemical load exerted on the oxygen assets of a body of
water when organic wastes are introduced into the water.
Cold Frame soap - A type of soap produced by solidification
by cooling and slicing into bars.
Condensate - The product resulting from a vapor condensing.
Cooling Water Slowdown - Whenever cooling water is reused
and run over atmospheric contactors (in turn cooled by am-
bient air) there is a buildup of contaminants. Periodically
it is necessary to dilute them or treat the cooling water to
"blow down" or rid the system of the concentrated contaminants.
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& cylindrical vessel of 681 - 2270 kg (1500 -
5000 Ib) capacity in which soap or synthetic surfactants
are mixed with builders prior to drying. It is often steam
jacketed.
De-aerator - A piece of equipment for removing air dissolved
or suspended in a fluid.
Detergent - Technically, any cleaning agent, including ordi-
nary soap, the new "synthetic" granules and liquids, many
alkaline materials, solvent, or even sand when used for
scrubbing, whether used in the home or in industry. In
popular speech, the term "detergent" is generally applied
to packaged cleaning products based on a surface active
ingredient such as ABS or LAS. Its cleaning power is re-
tained in hard water, contrary to the performance of soap.
Dissolved Oxygen - The oxygen dissolved in sewage, water,
or other liquid, usually expressed as milligrams per liter
or as per cent of saturation.
Effluent - The outflow of a sewer; a waste waterstream from
a manufacturing process or plant.
EyaEprator - A unit in which liquids are converted to gas.
Fat - Glycerol esters of long chain fatty acids of animal
or vegetable origin.
Fat Refining - Purification of fats by treatment with clay,
caustic, etc.
Fat ^Splitting - Various processes for hydrolysis of fatty
triglycerides to fatty acids and glycerine.
Fatty Acid - Naturally occurring straight chain carboxylic
acids which usually occur as triglyceride esters (fats).
Fatty Oil - Triglycerides which are liquid at room temperature.
£it£i£2_£3;i§G2§ ~ Also called pitching or finishing change,
is the final step in soap making in which clear water is
mixed with the soap to separate the neat soap from the
nigre.
Foots - The residue of refining fats or oils which contain
color bodies, insolubles, suspended matter, etc.
Full Boil^Process - Soap making where the neat soap is com-
pleted in the kettle and the by-product glycerine drawn off.
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.Heels - The residue remaining from any processing unit
after drawing.
Killing Change - The first step in soap manufacture where
fresh fat is brought into contact with a lye solution.
The start of the saponification process.
LAS - A new surfactant in which a straight chain hydro-
carbon has been joined to the benzene ring. It has a high
rate of biodegradability.
Low Grade Fatty Acids - These are contaminated fatty acids
derived from recovery of scrap, acidification of nigre, and
contaminated fatty acid raw materials.
Mazzonj Process - A proprietary process for manufacture of
soap.
rng/l - Milligrams per liter.
Neat Soap - An intermediate, completely saponified and puri-
fied soap containing about 20 - 30 percent water, ready for final
formulation into finished product.
New Source - Any building, structure, facility or installa-
tion from which there is or may be a discharge of pollutants
and whose construction is commenced after the publication of
the guidelines.
Nigre - The bottom layer which separates out in the last wash-
ing step of kettle boiling soap which contains the impurities
leading to poor color, odor, etc. Often contains 20 - 25 percent of
the kettle contents at that stage of the soap making and
possesses a soap content of 30 - 40 percent. The nigre can be
concentrated and salted out to yield a low grade colored
soap for sale.
No Discharge of Pollutants - No net increase (or detectable
gross concentration if the situation dictates) of any para-
meter designated as a pollutant to the accuracy that can be
determined from the designated analytical methods.
Oil - Fats found in liquid form at room temperature. Gly-
cerol esters of long chain fatty acids.
Oleum - A solution of SO3_ in sulfuric acid.
Operations and Maintenance Costs - Those required to operate
and maintain pollution abatement equipment. They include
labor, material, insurance, taxes, solid waste disposal, etc.
199
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JDH - a measure of the relative acidity or alkalinity of
water. A pH of 7.0 indicates a neutral condition. A
greater pH indicates alkalinity and a lower pH indicates
acidity. A one unit change in pH indicates a tenfold change
in acidity and alkalinity.
Phenol - Class of cyclic organic derivatives with the basic
formula C6H5OH.
Pjl odder - A powerful homogenizer which resembles a sausage
grinder in design; used for the final processing of bar
soap wherein the occluded air is removed (under partial
vacuum) and the individual soap particles melded into one
continuous homogenous whole prior to being cut up into bar
stock.
Polj.ution - The presence in a body of water (or soil or air)
of substances of such character and in such quantities that
the natural quality of the body of water (or soil or air) is
degraded to a point where the water is rendered useless or
offensive to the senses of sight, taste or smell. Contami-
nation may accompany pollution. In general, a public health
hazard is created, but in some cases only economy or esthetics
are involved as when waste salt brines contaminate surface
waters or when foul odors pollute the air.
Pretreatment - Treatment provided prior to discharge to a
publicly owned treatment works.
Process Water - In the manufacture of soap and detergent,
all waters that come into direct contact with the raw mater-
ials, intermediate products, final products or contaminated
waters or air.
Refractory BOD5- Organic substances which are slowly or
incompletely degraded by microorganisms.
Saponification - The hydrolysis of an ester into its
corresponding alcohol and soap.
Secondary Treatment - Biological treatment provided beyond
primary clarification, usually aerobic activated sludge,
trickling filters or lagoon systems.
Semi-boil Process - That soap making process wherein the
exact (stoichiometric) amount of caustic is added to fat
for saponification, and the soap is then run off into frames
or further processed without the benefit of removal of by-
product glycerine.
ZUO
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Sewage - Water after it has been fouled by various uses.
From the standpoint of source it may be a combination of
the liquid or water-carried wastes from residences, office
buildings and institutions together with those from indus-
trial and agricultural establishments, and with such ground-
water, surface water and storm water as may be present.
Sewer Lyes - Waste sodium hydroxide from reclaiming of scrap
soap.
Silicates - A chemical compound containing silicon, oxygen,
and one or more metals. In soaps and detergents, sodium
silicates are added to provide alkalinity and corrosion
protection.
Soap Boiling - The process of heating a mixture of fats/oils
with caustic solution until the fatty ester is split and
the alkaline metal salt formed, glycerine being released in
the process. The step where saponification takes place.
Soda Ash - Sodium carbonate.
Spray Drying Tower - A large vessel in which solids in
solution or suspension are dried by falling through hot gas.
Stabilizgrg - An additive which gives physical and/or
chemical stability to a formulation.
Still - A distillation apparatus.
Strong Change - That step in the soap making process where
virgin, strong lye is added to the already saponified fat
to finally complete saponification of remnants of fat.
Surface Waters - Navigable waters; the waters of the U.S.
including the territorial seas.
Sweet Water - By-product aqueous glycerine from soap manu-
facture.
Synthetic Detergent - chemically tailored cleaning agents
soluble in water or other solvents. Originally developed
as soap substitutes. Because they do not form insoluble
precipitates, they are especially valuable in hard water.
They are generally combinations of surface active agents
and complex phosphates to enhance detergency.
TDS - Total dissolved solids.
201
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