DRAFT
DEVELOPMENT DOCUMENT FOR
EFFLUENT LIMITATIONS GUIDELINES
AND STANDARDS OF PERFORMANCE
TEXTILE INDUSTRY
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
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NOTICE
The attached document is a DRAFT REPORT. It includes techni-
cal information and recommendations prepared by the Effluent Guide-
lines Division of the United States Environmental Protection Agency
("EPA") regarding the subject industry. It is being distributed
for review and comment only. The report is not an official EPA
pulication and it has not been finally reviewed by the Agency.
The report, including the recommendations, will be undergoing
extensive review by EPA, Federal and State agencies, public interest
organizations and other interested groups and persons during the
coming weeks. The report and in particular the recommended effluent
limitations guidelines and standards of performance is subject to
change in any and all respects.
The regulations to be published by EPA under sections 304(b)
and 306 of the Federal Water Pollution Control Act, as amended,
will be based to a large extent on the report and the comments
received on it. However, pursuant to Sections 304(b) and 306 of
the Act, EPA will also consider additional pertinent technical
and economic information which is developed in the course of review
of this report by the public and within EPA. EPA is currently
performing an economic impact analysis regarding the subject industry,
which will be taken into account as part of the review of the report.
Upon completion of the review process, and prior to final promulgation
of regulations, an EPA report will be issued setting forth EPA's
conclusions concerning the subject industry and effluent limitations
guidelines and standards of performance applicable to such industry.
Judgments necessary to promulgation of regulations under Sections
301 (b) and 306 of the Act, of course, remain the responsibility
of EPA. Subject to these limitations, EPA is making this draft
report available in order to encourage the widest possible parti-
cipation of interested persons in the decision making process at
the earliest possible time.
The report shall have standing in any EPA proceeding or court
proceeding only to the extent that it represents the views of the
individuals who studied the subject industry and prepared the informa-
tion and recommendations. It cannot be cited, referenced, or represented
in any respect in any such proceedings as a statement of EPA's views
regarding the subject industry.
U. S. Environmental Protection Agency
Office of Air and Water Programs
Effluent Guidelines Division
Washington, D. C. 20460
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DRAFT
DRAFT
DEVELOPMENT DOCUMENT FOR
EFFLUENT LIMITATIONS GUIDELINES
AND STANDARDS OF PERFORMANCE
TEXTILE INDUSTRY
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
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DRAFT
ABSTRACT
The 1967 Census of Manufacturers lists approximately 7,000 plants in the
textile industry (SIC 22) for which 1972 production was estimated at 1C
billion linear meters (11 billion linear yards) of fabric. The total
process water consumption of the industry in 1972 is about 473 billion
liters (125 billion gallons) per year. However, it appears that more
than 95 percent of this water consumption was accounted for by only
some 680 plants.
In 1968, only about 28 percent of the total wastewater received secondary
treatment, with a further 27 percent going to municipal sewage plants.
Installation of new or improved waste treatment plants has proceeded
rapidly over the last few years and roughly 15 percent
of the waste effluent presently receives secondary treatment and that
another 35 percent goes to municipal plants. This treatment removes
about 70 percent of the BOD raw waste load from the effluent.
Many textile plants are 'dry' in that they have effectively no water use
and the •wet* processing plants are not adequately defined by the sub-
categories of SIC 22. For waste treatment purposes,
the water using portion of the industry has been divided into seven categories:
(1) wool scouring; (2) wool finishing; (3) greige goods mills; (4) woven
fabric finishing; (5) knit fabric finishing; (6) carpet mills; and (7)
stock and yarn dyeing and finishing.
Wool processing was kept as a separate category because of the high raw
waste loads associated with the processing of this fiber. Greige goods
mills are essentially dry plants and therefore have minimal waste loads.
Many knitting mills and yarn and thread mills which do not carry out
dyeing or finishing operations also fall into this category.
Finishing plants (categories, t, 5, and 7), together with carpet mills
(category 6), constitute the major portion of the •wet1 processing
industry.
Synthetic fibers used alone or in blends with other fibers are used in
all sections of the industry. In fact this tendency to increasing use
of fiber blends blurs the distinction between categories, but for the
present there are sufficient unique differences to maintain the seven
categories.
In all categories there are plants that show greater than
90 percent BOD removal by conventional secondary biological treatment.
This degree of treatment is the basis for Level I
effluent guidelines to be achieved by the industry in 1977.
For Level II guidelines, to be achieved by 1983
NOTICE: These arc tentative recommendations based upon information in this
report and are subject lo c':an-e based upon comments rece'vcd v.* furthpr
rev.cw by EPA.
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DRAFT
zero discharge is recommended as being technically achievable by present techno
reverse osmosis or evaporation, followed by incineration of
effluent. However, it appears to be associated with a relatively high
cost.
New source performance standards (i.e.. Level III) should be set at
the same Level II guidelines, although the technical risk associated
with installing this technology now is somewhat greater.
'; >'.:•::.;.' .:' '. imir.c-r
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DRAFT
SECTION I
Conclusions
1. The textile industry has over 7,000 plants, but many of these carry
out only dry operations and many more are connected to municipal treat-
ment systems. About 680 wet process plants account for 95 percent of
the total water used U73 billion liters per year or (125 billion gallons
per year). Only about 20 percent of this water is discharged untreated;
the rest undergoes municipal or on-site secondary waste treatment.
2. After consideration of previously proposed categorization schemes
and evaluation of waste effluent characteristics we conclude that the
industry can be conveniently divided into seven categories as follows:
(1) Wool Scouring
(2) Wool Finishing
(3) Greige Goods Mills
(4) Woven Fabric Finishing
(5) Knit Fabric Finishing
(6) Carpet Mills
(7) Stock and Yarn Dyeing and Finishing
(8) Specialized Finishing
Raw wastes from all categories show high treatability by secondary
biological treatment.
3. The performance of plants with respect to BOD removal in all seven
categories have been found. These plants remove substantially more than
90 percent of the BOD. Implementation of the proposed Level I
guidelines will require approximately 95 percent BOD removal for the
entire industry (weighted average) by July 1, 1977. With the exception
of wool scouring, which has a very high raw waste load, all categories
can achieve an average BOD of less than 25 mg/1, i.e., equivalent to or
better than acceptable municipal treatment.
Of the heavy metals chromium is the only one of general concern;
chromium using plants typically average 1 to 1U mg/1 in their waste
effluent. The technology for chemically removing chromium is well known
and should be applicable to this industry.
1. Wool scouring shows the highest raw-waste discharge concentration,
averaging 2,000-3,000 mg/1 BODS, or 100-200 kg BOD/1000 kg of product,
and after biological waste treatment, effluents have a relatively high
BOD 5. There are about 22 plants in this category; of the five largest.
NOTICE": These ::c tErts'ivc roro~!~cr:'2Vcns tarsi u?on information in Ihis
report e:'- aie su'.'jccl !o c' a-re L::3l iron comments rccc.'.cd 2-id further
teview b> CI:A.
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DRAFT
three have waste treatment and two discharge to municipal systems. The
Wool Finishing segment of the industry consists of approximately 100
plants, of which essentially all the larger ones have waste treatment
plants. One-third of the remaining plants have some waste treatment and
only about 10 percent have no treatment at present.
5. Over 75 percent of the larger cotton and synthetic finishing plants
(woven and knits) have waste treatment systems. Among the smaller ones,
we estimate 60 percent have their waste treated in municipal systems.
Greige goods mills are essentially dry plants and most are currently on
municipal systems. Of the fifty largest carpet mills, practically all
have their own waste treatment or are on a municipal system. Sixty
percent of the carpet industry is within one town which handles the
waste from all of these plants by municipal treatment.
6. Textile industry waste effluent shows such high treatability.
Treatment plants within the textile industry have extended aeration
activated sludge , often followed by a long (1 to 5 days) residence time
in a polishing lagoon. Plants located in urban areas may find it more
costly to meet guidelines set by the exemplary mills than will other
plants which have available land.
7. Further improvement in the quality of these effluents should be
directed towards the reduction of the dissolved salts. No discharge is
established for Level II guidelines and Level III standards.
8, There is essentially no difference between old and new plants in raw
waste loads per unit of product. In contrast to some other industries,
old plants continually modernize and add new equipment. Although some
sub-processes do show significant differences, for example, the use of
pressure becks versus atmospheric becks in the dyeing of synthetic yarns
-these differences are not sufficient to affect guideline values.
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DRAFT
SECTION II - Recommendations
Basis For Guidelines
The RFP defines Level I Guidelines (to be achieved by 1977) as the BEST
PRACTICABLE CONTROL TECHNOLOGY CURRENTLY AVAILABLE as exemplified by the
average of the best plants existing in the industry. Level 1 guidelines
are primarily based on removal of BOD by conventional biological
treatment as typified by activated sludge or aerated lagoons. Treatment
Technology is also available (although not always well practiced) for
removal of COD, suspended solids, heavy metals, color and control of pH
and Level I guidelines are also recommended for these parameters.
The RFP defines Level II Guidelines (to be achieved by 1983) as the BEST
AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE as exemplified by the best
existing plant, or modified if necessary by the application of
technology from other industries. This industry as yet has only a few
no discharge system or systems that have 100JE recycle. Therefore, it is
recommended that Level II guidelines be based on the application of
desalinization techniques.
New source performance standards (Level III) should be based on the
application of Level II technology with the maximum possible reduction
of process water use through the utilization of in-process controls and
water reuse.
LEVEL I GUIDELINES
Guidelines for each category of the textile industry are summarized in
Table II-l, which gives the average effluent limits that are not to be
exceeded on a monthly average and daily composite basis.
The recommended guidelines for BOD, COD and suspended solids are shown.
For all industry categories, guidelines are recommended for chromium,
phenol, color and pH, recognizing that effluents from some categories do
not contain all of these pollutants.
LEVEL II GUIDELINES AND LEVEL III PERFORMANCE STANDARDS
As a first step, reductions (in most cases by a factor of two) in stan-
dard water usage is foreseen.
The removal of BOD, COD and suspended solids by physical, chemical and
biological processes provides the pretreatment necessary for
-.I i.i ii;is
u'-on cor.wcr.u tccc-.voj and lurthet
tev.ew by [PA.
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DRAFT
desalinization techniques for removal of dissolved solids and water
reuse.
.; -::j:t!ter
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TABLE II-1
SUMMARY OF LEVEL I POLLUTANT GUIDELINES - (a)
Maximum 20 Working Day Averages,
kg/1000 kg (lb/1000 Ib)
1.
2.
3.
4.
5.
6.
7.
Category
Wool Scouring
Wool Finishing
Greige Goods
Woven Fabric Finishing
Knit Fabric Finishing
Carpets
Stock and Yarn Dyeing
BOD
2.85
5.1
0.15
3.3
3.6
2.1
4.0
COD Suspended Solids PH^u;
28
51
1.17
45
45
21
52
2.0
7.6
0.22
5.0
6.1
2.4
6.1
6-3.5
6-8.5
6-S.5
6-8.5
6-3.5
6-8.5
6-8.5
(a) In addition to the guidelines shown, the following apply to all categories
Coliform organisms 200/ml MPN,
Total chromium-not to exceed 0.25 mg/1
Phenols-not to exceed 0.25 mg/1
Col or-not exceed 200 ADMI units
(b) Values are the maximum permitted range.
Note: Daily maximum may not exceed twice the maximum 20 working day average.
O
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DRAFT
SECTION III
Introduction
Purpose and Authority
Section 301(b) of the Act requires the achievement, by not later than
July 1, 1977, of effluent limitations for point sources, other than
publicly owned treatment works, which are based on the application of
the best practicable control technology currently available as defined
by the Administrator pusuant to Section 30H(b) of the Act. Section
301 (b) also requires the achievement, by not later than July 1, 1983, of
effluent limitations for point sources, other than publicly owned
treatment works, which are based on the application of the best
available technology economically achievable which will result in
reasonable further progress toward the national goal of eliminating the
discharge of all pollutants, as determined in accordance with
regulations issued by the Administrator pursuant to Section 305(b) to
the Act. Section 306 of the Act requires the achievement by new sources
of a Federal standard of performance providing for the control of the
discharge of pollutants which reflects the greatest degree of effluent
reduction which the Administrator determines to be achievable through
the application of the best available demonstrated control technology,
processes, operating methods, or other alternatives, including, where
practicable, a standard permitting no discharge of pollutants.
Section 30U(b) of the Act requires the Administrator to publish within
one year of enactment of the Act, regulations providing guidelines for
effluent limitations setting forth the degree of effluent reduction
attainable through the application of the best practicable control
technology currently available and the degree of effluent reduction
attainable through the application of the best control measures and
practices achievable including treatment techniques, process and proce-
dure innovations, operation methods and other alternatives. The regu-
lations proposed herein set forth effluent limitations guidelines
pursuant to Section 30*»(b) of the Act for the textile manufacturing
source category.
Section 306 of the Act requires the Administrator, within one year after
a category of sources is included in a list published pursuant to Sec-
tion 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. 162U), a list of 27 source categories.
Publication of the list constituted announcement of the Administrator's
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DRAFT
intention of establishing, under Section 306, standards of performance
applicable to new sources within the textile manufacturing source
category, which was included within the list published January 16, 1973.
Methodology
The effluent limitations guidelines and standards of performance pro-
posed herein were developed in the following manner. The textile
industry was first categorized for the purpose of determining whether
separate limitations and standards are appropriate for its different
segments. Considerations in the industry categorization process
included raw materials, the products, manufacturing process, and raw
waste characteristics.
The raw waste characteristics for each category were identified through
analyses of: (1) the sources and volumes of water and waste waters and
(2) the constituents (including thermal) of all waste waters including
toxic or hazardous constituents and other constituents which result in
taste, odor, color, or aquatic organisms. The constituents of waste
waters that should be subject to effluent limitations guidelines and
standards of performance were identified.
The full range of control and treatment technologies existing within
each category was identified. This included an identification of each
distinct control and treatment technology, including both in-plant and
end-of-process technologies, which are existent or capable of being
designed for each subcategory. It also included an identification, in
terms of the amount of constituents (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 were also identified. The non-water quality environmental impact
were also identified, e.g., the effects of the application of such
technologies upon other pollution problems, including air, solid waste,
noise, and radiation. The energy requirements of each of the control
and treatment technologies were identified as well as the cost of the
application of such technologies.
The information, as outlined above, was then evaluated to determine what
levels of technology constituted the "best practicable control technolo-
gy currently available,11 "best available technology economically
achievable" and "best available demonstrated control technology,
processes, operating methods, or other alternatives." In identifying
such technologies, various factors were considered. These included the
total cost of application of technology in relation to the effluent
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DRAFT
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), the treatability of the wastes, and water use
practices.
The data for the identification and analyses were derived from a number
of sources. These sources included EPA research information, published
literature, previous EPA technical guidance for textile manufacture,
various industry associations, qualified technical consultation, and on-
site visits and interviews at exemplary textile manufacturing plants in
the United States. All references used in developing the guidelines for
effluent limitations and standards of performance for new sources
reported herein are listed in chapter XIV.
General Description of the Industry
Since 1638, when the first commercial mill was erected at Raleigh,
Massachusetts, the U.S. textile industry has burgeoned to a point where
there are nearly 7100 plants in 47 states, employing about one million
people, and in 1972 selling goods valued at just under $28 billion.
These plants range from highly integrated manufacturing complexes that
process basic raw materials into finished products, to small non-
integrated contract plants that process goods owned by other producers.
According to the 1967 Census of Manufacturers, the textile industry, SIC
Code 22, contains ten major SIC classifications. In recent decades, the
industry has been concentrating in the Southeast--notably in the
Carolinas, Georgia and Alabama—and this trend is continuing. Today 38
percent of the textile plants are in the Southeast and 92 percent are on
the eastern seaboard. The rest, as shown by Table III-l and
8
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DRAFT
III-2 are scattered thinly throughout the country. Knitting mills, with
almost 2,700 plants listed, constitute the largest group but there are
also about 1,000 weaving mills of various types and over 1,000 plants
which process miscellaneous textile goods. Most of the textile industry
is contained within EPA Regions 1, 2, 3 and 4, with Region 4 accounting
for a major proportion of the industry.
Table III-1
Region Number of Mills ft .Tof.ri Total
South 2656 38
Mid-Atlantic 2821 40
New England 978 14
North Central 321 4
West 304 _4
7080 100
Source: 1967 census of Manufacturers
The industry's basic raw materials are wool, cotton, and man-made
fibers. Of the roughly 5.0 billion kilograms (11 billion pounds) of raw
materials consumed by the industry in 1972, wool accounted for about
0.09 billion kilograms (0.2 billion pounds), cotton for 4.0 billion
kilograms (4 billion pounds) and man-made fibers for 3.2 billion
kilograms (7 billion pounds).
Among the man-made fibers, the most important are rayon, acetate, nylon,
acrylic, polyester, polypropylene, and glass fiber.
The natural fibers are supplied in staple form, (staple being short
fibers). The man-made fibers are supplied as either staple or
continuous filament. In either case the fiber is spun into yarn, which
is simply a number of filaments twisted together. The yarn is woven of
knit into a fabric, and the fabric then dyed and treated to impart such
characteristics as shrink resistance, crease resistance, etc. The
finished fabric is delivered—directly or through convertors, jobbers,
and wholesalers-to the manufacturer of textile products.
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o
Table III-2
Number of Textile Plants by Geographic Areas:
1967
NORTHEAST REGION
New England Div.
Maine
New Hampshire
Vermont
Massachusetts
Rhode Island
Connecticut
Mid. Atlantic Div.
New York
New Jersey
Pennsylvania
NO. CENTRAL REGION
E. No. Central Div.
Ohio
Indiana
Illinois
Michigan
Wisconsin
W. No. Central Div.
Minnesota
Iowa
Missouri
Textile
Mills
Products
22
7,080
3,799
978
56
79
14
400
293
136
, 2,821
1,521
558
742
>,' 321
/. 251
74
13
76
30
58
/. 70
24
7
34
Weaving
Mills
Cotton
221
393
78
21
4
1
-
_
4
4
57
17
25
15
-
_
-
-
-
-
-
_
-
-
-
Weaving
Mills
Synthetic
222
396
196
64
7
9
-
19
23
6
132
33
37
62
7
_
-
-
-
-
-
3
-
-
2
Weaving &
Finishing
Mills-Wool
223
310
216
127
18
16
7
41
36
9
89
39
10
40
22
12
5
-
3
-
2
10
6
-
3
Narrow
Fabric
Mills
224
384
258
121
-
15
-
37
51
15
137
50
31
56
14
9
3
-
3
-
-
5
-
-
-
Knitting
Mills
225
2,698
1,616
113
3
15
-
49
15
28
1,503
964
192
347
76
61
19
i
14
2
25
15
8
-
5
Textile
Finishing
Exc. Wool
226
641
423
98
-
4
-
45
31
18
325
144
131
50
29
24
7
-
13
1
3
_
-
-
-
Floor
Covering
Mills
227
385
83
35
3
-
-
19
10
1
48
16
3
29
13
12
-
2
-
-
3
_
-
-
-
Yarn &
Thread
Mills
228
768
304
128
11
11
-
53
34
16
176
70
28
78
15
15
5
-
4
-
5
_
-
-
-
Misc.
Textile
Goods
229
1,105
625
271
7
6
-
129
89
39
354
138
101
05
141
111
28
10
35
21
17
3D
8
—
IB
Tl
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Table 111-2 (Con't)
Textile Weaving Weaving Weaving & Narrow Textile Floor Yarn & Misc,
Mills Mills Mills Finishing Fabric Knitting Finishing Covering Thread Textile
Products Cotton Synthetic Mills-Wool Mills Mills Exc. Wool Mills Mills Goods
221
22
SOUTH REGION
So Atlantic Div.
Delaware
Maryland
Virginia
West Virginia
North Carolina
South Carolina
Georgia
Florida
L. Sc. Centra]. Div.
Kentucky
Tennessee
Alabama
Mississippi
W. So. Central Div
Arkansas
Louisiana
Oklahoma
Texas
WEST REGION
Mountain Division
Utah
Pacific Division
Washington
Oregon
California
222
223
224
225
226
227
228
229
2,656
2,214
13
30
109
5
1,260
359
407
31
34':
27
149
141
27
98
16
10
6
66
304
18
5
286
20
20
245
307
254
_
-
6
-
67
112
67
-
34
-
4
29
1
19
3
-
-
15
-
«
-
-
_
_
190
178
-
-
22
-
77
57
21
_
10
-
3
6
-
2
-
-
_
2
-
_
-
_
-
-
-
52
43
-
3
10
1
6
11
11
-
7
-
2
2
-
2
-
-
-
2
20
_
-
18
1
8
^\
101
83
-
6
9
1
40
19
6
-
18
-
6
7
2
_
-
-
_
-
11
_
-
11
-
-
10
910
770
8
5
30
3
630
38
44
12
130
10
76
29
15
10
5
-
-
4
96
5
2
91
6
5
80
170
145
2
5
9
-
77
31
16
-
19
-
11
6
-
6
1
-
1
-
19
-
-
17
-
-
16
231
199
-
-
3
-
35
19
142
-
24
-
13
7
1
8
3
_
1
-
58
-
-
57
-
-
56
443
387
-
5
8
-
262
41
70
1
51
2
13
35
-
_
-
-
_
-
6
-
-
5
-
- -
5
252
155
3
-
12
-
66
31
30
-
^ ~^
A
21
20
6
46
i
9
-
31
87
-
-
81
-
-
6
O
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DRAFT
The many woven fabrics are produced by variations in -the weaving
pattern. Plain, or tafeta, weaves give such fabrics as broadcloth,
calico, cheesecloth, muslin, seersucker, flannel and tweed. Twill
weaves are represented by serge, herringbone, jersey, gabardine, and
ticking. Because of their superior strength, twill fabrics are used for
work clothes and men's suits. Satin weaves are smooth but weak; the
best known are crepe satin, sateen, and damask. Dobby and Jacquard
weaves are used to produce patterned fabrics. Dobby weaves are used in
men's shirting and women's dress fabrics. Jacquard weaves are used
extensively for upholstery and drapery materials. Finally, there are
the pile weaves, which include velvets, plushes, corduroys and turkish
toweling.
In transforming a fiber into one of these woven fabrics, two types of
processes are used: wet and dry. The SIC code breakdown is not particu-
larly useful for evaluating the waste effluent problems of the textile
industry. These codes are gouped primarily by the process used—e.g.,
weaving or knitting—whereas the waste effluent problems stem from all
the wet processes which are used to desize, wash, dye and finish the
textile fabric. The wet processes of interest include: scouring, de-
sizing, mercerizing, bleaching, bonding and laminating. Dry processes
include: spinning, weaving and knitting. Although SIC Code 226
identifies textile finishing, code 221 identifies weaving mills which
may also be integrated mills that have a finishing operation or may be
greige goods mills that have only dry processing. Knitting mills fall
into a similar category; many of the mills identified as knitting mills,
in fact, process dyed yarns and, therefore, essentially carry out dry
operations.
There is no exact figure for the number of wet processing plants or the
total water use by the industry, but the Census of Manufacturers gave
for 1968 under Textile Mill Products a total of 684 wet plants which
consume 412 billion liters (109 billion gallons) of process water per
year. (This includes sanitary and cooling water, etc.) A more recent
estimate, by the American Textile Manufacturers' Institute in 1970,
found 346 plants using 394 billion liters (104 billion gallons) per
year, estimated to be 83 percent of the total industry use.
Table III-3 gives details of the process water used and discharged
divided as far as possible according to the ADL categories. The largest
water users are undoubtedly the finishing plants, with a total of 269
billion liters (71 billion gallons) per year, averaging 2800 cubic
meters per day (0.73 million gallons per day). The next highest
category is the wool finishing operations, with 47.3 billion liters
(12.5 billion gallons) per year averaging 27000 cubic meters per day
12
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DRAFT
(0.7 million gallons per day) but consisting of a much smaller segment
of the textile industry.
A summary of this data is presented in Table III-1, which shows that 110
billion liters (29 billion gallons) per year or 26.6 percent of the
water was discharged to municipal sewers and 73.2 percent or 303 billion
liters (80 billion gallons) per year to surface water. The 73.2 percent
also divides into 2H.2 percent that received no treatment, 21 percent
that received primary treatment and 28.2 percent that received secondary
treatment before discharge. Since 1968 many more treatment plants have
been built and from a consideration of RAPP data and the recent survey
by the ATMI, we estimate that about 35 percent of the water used is now
discharged to municipal sewers, 15 percent receives no treatment, 5
percent receives primary treatment and U5 percent receives secondary
treatment. Undoubtedly, the smaller mills or those using the least
amounts of water have found it more economical to use municipal
treatment instead of constructing their own facilities.
13
-------
Table III-3 Water Use by the. Textile Industry
Average
Value of No. of Process Water Water Discharged
Shipments Plants Water Used use/plant Sewer Surface
Treated Before Discharge
Total Ponds
SIC
Code
22
2297
2231
-2233
2211
-2221
-2241
226
225
227
228
-2283)
ADL
Category
Total |
i
1
2
4 1
!
5
j
6
7
(Million 106 cu m/yr
dollars) (BG/yr)
413.
9,235.5 684 (109.0)
2.6
49.5 9 (0.7)
47.3
758. 2 67 (12.5)
I 269.
; 4,787.3 348 (71.1)
32.
1,119.7 100 (8.4)
30.
! 1,067.6 50 (7.8)
21.
660.3 60 (5.6)
cu n/d 106
(MGD)
2100.
(0.56)
1100.
(0.28)
2600
(0.68)
2800
(0.73)
1100.
(0.30)
2100.
(0.56)
1200.
(0.33)
cu m/yr
(BG/yr)
192.
(50.6)
.38
(0.1)
15.
(3.9)
99.5
(26.3)
28.
(7.4)
23.
(6.1)
16.
(4.2)
10° cu ra/yr
(BG/yr)
306.
(80.9)
3.4
(0.9)
42.4
(11.2)
213.
(56.4)
11.
(2.9)
11.
(2.8)
16.
(4.3)
106 cu ra/yr
(BG/yr)
203
(53.7)
2.3
(0.6)
26.
(6.9)
137.
(36.3)
8 . ~
(2.3)
11..
(2.3)
15.
(3.9!
10° cu m/yr
(BG/yr)
117.
(30.8)
_
(-)
15.
(3.9)
74.9
(19.8)
2.3
(0.6)
6.4
(1.7)
14.
U'8>
Source: Department or Coimnerce — 1967 Census of Manufacturers
-------
Table III-4 Water Discharged by the Textile Industry
1968
1972
To Municipal Sower
To Surface Water:
1. No Treatment
2. Primary Treatment
3. Secondary Treatment
TOTAL PROCESS WATER
Amount
106 cu m/yr
BG/yr
110.
(29.)
99.5
(26.3)
86.7
(22.9)
116.
(30.8)
413.
(109.)
Percent
of
Total
26.6
24.2
21.0
28.2
100.0
Amount
10° cu m/yr
BG/yr
166.
(44.)
71.
(19.)
24.
(6.)
213.
(56.)
473.
(125.)
Percent
of
Total
35.
15.
5.
45.
100.0
Q
Sources: Department of Commerce 1967 Census of Manufacturers
Refuse Act Permit Program Data
American Textile Manufacturers Institute
Arthur D. Little, Inc. Estimates
-------
DRAFT
SECTION IV - Indus-try Categorization
PREVIOUS APPROACHES
In deriving this industry categorization system, existing
categorizations and other previous attempts at categorization have been
considered. The principal systems investigated were:
a. SIC codes. These codes do not lend themselves to a classi-
fication of the industry with respect to characterization
of the pollution loads generated. For example. Category
3, Greige Goods, includes 10 SIC categories.
b. The method advanced by the report, "A Simplification of Textile
Waste Survey and Treatment" by Masselli, Masselli and Burford.
This approach consists of synthesizing the raw waste load from
a textile mill by additive contributions of the chemicals used.
Tables of BOD values for many chemicals are given in the report.
This method was judged too difficult to be implemented by persons
not versed in Textile Chemistry and not knowledgeable about the
chemicals used.
c. The previous Arthur D. Little Report prepared for the EPA.
This approach employed unit processes to synthesize the raw waste
loads. This method was also judged too difficult to implement
by the EPA.
d. The preliminary system developed by the EPA in the "Denver"
guidelines study.
e. The system developed by the Institute of Textile Technology
and Hydrosciences in the recent study for American Textile
Manufacturer's Institute, Inc., and carpet and Rug Institute.
Based on knowledge of the various pollution problems, loads generated
by the different unit operations in the textile industry, actual and
potential waste treatment practices and current manufacturing and
processing practices, these five approaches were combined and
simplified.
The last two methods (d and e) and the present one have in common a
categorization according to the products produced by a mill that in turn
relates to type of wastes; the differences are in matters of judgment as
to the balance between simplicity and how well a given category
16
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DRAFT
accurately describes the wastes generated. The objective is to arrive
at useful, realistic guides to field EPA personnel,
A comparison of the EPA and the ATMI/CBI categorizations with those used
in this study is given in Table IV-1. The SIC codes, in relation to the
ADL categories, are shown in Table IV-2. This latter table also
indicates the number of plants in each category.
17
-------
TABLE IV-1
INDUSTRY CATEGORIZATION
o
XJ
".T
ADL
1. Wool Scouring
2. Wool Finishing
3. Greige Goods Mill
4. Woven Fabric Finishing
5. Knit Fabric Finishing
Carpet Mill
Stock & Yarn, Dyeing
and Finishing
EPA
1. Wool Scour and Finish Mill (Integrated) 1.
2. Wool Finish Mill 2.
3. Greige Goods Mill - Woven and Knitted Goods 3.
4. Finishing Mill - Woven Products of 4.
Cotton, Synthetics, and Blends
5. Finishing Mill - Knitted Products of
Cotton, Synthetics, and Blends
6. Integrated Woven Goods Mill (Includes
Manufacture of Greige Goods)
7. Carpet Mill - Dyeing and Finishing
(Excluding Carpet Backing)
8. Integrated Carpet Mill
9. Yarn Dyeing Plants - All Yarns
ATMI
Wool Scouring
Wool Finishing
Greige Mi.ll
Woven Fabric Finishing
5. Knit Fabric Finishing
Greige Mill + Finishing
Fabric
Carpet Backing & Foam
8. Integrated Carpet Mill
9. Stock & Yarn Dyeing
& Finishing
10. Greige Mill -I- Finishing
& Fabrics
11. Combined Materials
Finishing - Stock, Yarn
Wovens, Knits
12. Multiple Operation,
Commission House
Specialized Finishing
13. Specialized Finishing
-------
DRAFT
NUMBER OF TEXTILE PLANTS BY SIC CODE - Table IV-2
SIC No. of ADL
Code Plants Description Category
WEAVING MILLS
2211 393 Broad Woven Fabric, Cotton 364
2221 396 Broad Woven Fabric, Synthetic 364
2231 310 Broad Woven Fabric, Wools 2
2241 384 Narrow Fabrics 364
1483 Sub Total
KNITTING MILLS
2251 355 Womens Hosiery 5 (3)
2252 448 Hosiery (except Womans) 5 (3)
2253 1179 Knit Outerwear 3
2254 113 Knit Underwear 3
2256 541 Knit Fabric 5 (3)
2259 62 Knitting Mills, N.E.C. 3
2698 Sub Total
DYEING 8 FINISHING
(except Wool & Knits)
2261 216 Broad Woven Fabrics, Cotton 4
2262 233 Broad Woven Fabrics, Synthetic 4
2269 192 Finishers, N.E.C. 4&7
641 Sub Total
CARPET MILLS
2271 61 Woven Carpets 366
2272 244 Tufted Carpets 366
2279 80 Carpets, N.E.C. 366
385 Sub Total
YARN 6 THREAD MILLS
2281 377 Yarn Spinning, Cotton 6 Synthetics 3
2282 181 Yarn Twisting, etc. Cotton 6 Syn. 367
2283 135 Yarn, Wool including Carpet 2
18
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DRAFT
2284 75 Thread Mills 367
Sub Total
19
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DRAFT
MISCELLANEOUS TEXTILES
2291 40 Felt Goods (except wool) 8
2292 1U2 Lace Goods 3S4
2293 151 Padding and Upholstery 3
229U 1U1 Processed Waste 3
2295 178 Coated Fabrics (excepty Rubberized) 8
2296 20 Tire Cord 8
2297 68 Wool Scouring 1
2298 169 Cordage and Twine
2299 196 Textile Goods, N.E.C. 3SU
1105 Sub Total
20
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DRAFT
PROPOSED CATEGORIZATION
The system derived efficiently characterizes mills in the textile
industry, according to their waste effluent problems. The system
provides eight categories and takes account of different fiber types in
addition to the pollution effects of different types of unit operation.
Categories 1 and 2 essentially separate the wool processing section of
the textile industry because of its particular effluent problems.
Categories 3, H, 5 and 7 cover the various types of processing for
cotton and synthetic fibers. Category 6 covers the carpet industry and
Category 8 is limited to specialized types of processing. These
categories are described in detail in the following section, but will be
summarized here.
Category 1 - Wool Scouring
Wool scouring and topmaking is conveniently separated as a category
because a significant number of plants perform this function alone. The
initial washing and cleaning of wool generates a wide variety of organic
and inorganic products in the waste effluent. The raw wool contains
suint, dirt, and grease along with oils such as lanolin which are not
readily biodegradable. These extraneous materials account for 25-75
percent of the original weight. In addition, the preparation and
cleaning of wool require a heavy use of detergents. Recovery of wool
grease has some economic incentive in that it has market value.
However, even with grease recovery, wool scouring wastes present a
difficult waste to treat biologically
Category 2 - Wool Finishing
Wool finishing involves the use of specialized dyes peculiar to this
fiber which often result in the presence of chromium in the waste
effluent. In addition, phenols occur from dyeing polyester blends. Only
a small amount of pure wool is now processed. The bulk of the
operations involves wool-polyester blends which give high BOD loads from
the dye carrier which is used. The resulting wastes are similar to
those in Category 5, Knit Fabric Finishing.
Several major mills have integrated wool scouring and top making with
wool finishing. Such mills can be accomodated by a combination of
Categories 1 and 2.
Category 3 - Greige Mills
21
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DRAFT
Although there are many greige goods mills, they carry out mainly dry
operations (with the exception of sizing) and hence contribute little to
the overall waste problems of the textile industry. In many plants the
sanitary BOD load is comparable to the process BOD load. This category
applies equally well to woven or knitted greige goods.
Greige goods manufacturing includes spinning and texturizing of yarns
which require a lubricating oil, similar to mineral oil. This oil is
applied to the fibers or yarns and stays with them, to be removed prior
to dyeing in the dye house. However, some oil finds its way into the
drains because of clean-ups and spills.
Prior to being woven, the yarns are coated with a sizing material to
give the yarn both lubrication and strength that will permit it to
withstand the severe mechanical demands of weaving. Cottons generally
are coated with starch and synthetics with polyvinyl alcohol. Wool and
wool blends are seldom sized, unless the yarns are quite fine. Since
most wool yarns are blends, both starch and PVA may be used. The
slasher, where the sizing is applied, is washed down about once a week
and thus contributes to the liquid wastes. Generally the waste flow
from the slashing operation represents less than 3% of the total.
Category ft .r- Woven Fabric Finishing
This category is one of the most important, because such plants consti-
tute much of the waste water effluent load in the textile industry.
Integrated woven fabric finishing mills are also included in this
category rather than in Category 3 because the greige goods section of
these mills contributes only a small amount to the overall effluent
load. The size used in preparing woven fabrics is a major contribution
to the BOD loan from the plant.
Two sizing compounds are commonly employed; starch and polyvinyl alcohol
(PVA). PVA tends to be less biodegradable than starch and therefore
presents a lower BOD level but contributes a high COD level. In
addition to high BOD, the wastes generally have high total dissolved
solids, color, and a variety of dispersing agents. They also may be
very alkaline from the use of caustic soda in mercerizing cottons.
The dyes and associated additives used in woven fabric finishing
represent the most complicated problem, since the BOD load and color can
vary considerably with the type of dye fabric being processed and the
color effects to be achieved. Subcategories of cotton and cotton-
polyester blends were suggested for this category at the start of this
study, because of the difference in size used on cottons and on
22
-------
DRAFT
synrthe-tics as well as the types of dyes and the dye assists used.
However, variations in unit operations from mill to mill have a greater
effect on the raw waste load than that observed between the proposed
subcategories. Consequently, such subcategory items were dropped. (The
same situation occurred in Categories 5, Knit Fabric Finishing, and 7,
Stock and Yarn, Dyeing and Finishing. A detailed discussion of this may
be found in Guidelines Section IX under Category 7.)
Processing steps in this category include cleaning the greige goods,
bleaching, mercerizing of cotton (treating with caustic) , dyeing,
washing and rinsing, followed by application of finishes such as soil
repellants, anti-statics, etc.
Category 5 - Knit Fabric Finishing
The main difference between woven and knit fabric finishing is that the
sizing/desizing and mercerizing operations are not required for knits;
therefore, BOD levels are lower. Otherwise, the problems from finishing
of the different fibers (cotton, polyester, and other synthetics) are
similar to those from woven fabric finishing. It was first thought to
be necessary to provide three adjustments in this category according to
the type of fiber being processed, i.e., cotton, polyester, and other
synthetics. As mentioned under Category 4, however, variations in unit
operations obscure the benefits from such subcategorization.
Category 6 - CarpetMills
Carpet mills form a distinct part of the industry although their
effluents are similar in many ways to those of Category 5, Knit Fabric
Finishing. Carpets use mostly synthetic fibers (nylon, acrylics and
polyesters) but some wool is still processed. As in Category 2, Wool
Finishing, such wool carpet mills produce synthetics as well. As a
result, no subcategory for wool carpets is proposed.
Carpet sometimes is backed with latex in a separate plant and represents
a particular problem for the disposal of suspended solids. The EPA and
the ATMI categorization systems allow two different categories to take
care of this problem. However, carpet is backed in separate mills
mostly in concentrated industry areas, principally Dalton, Georgia,
where shipment between mills is not a problem. Carpet mills in more
remote areas that have their own treatment plants often do latexing in-
plant with the finishing. Latex is settled in separate basins prior to
release of those segregated streams to treating; hence the additional
JLoad on integrated mills is negligible. Mills that perform latexing
only are treatable by coagulation to a level to meet recommended
23
-------
DRAFT
guidelines for this category. Therefore, no separate category or
subcategory is proposed for latex mills.
Category 7 - Stock and Yarn Dyeing and Finishing
Yarn dyeing and finishing are different from woven fabric finishing
because there is no sizing and desizing operation. They are different
from knit fabric finishing because of their mercerizing operations and
water use. The combined differences are sufficient to justify a
separate category. The waste loads from this type of plant can vary
more than those from other types of integrated textile mills or
finishing mills. Many multiple-operation, commission houses fall under
this category.
As in Categories H and 5, this category was considered as a candidate
for subcategories for different fibers but as discussed in Category 4,
variations in unit operations obscure the benefits of such division.
Category 8 - Specialized Finishing
In this category various miscellaneous processes have been examined.
The following are included in SIC 22: Coated Fabrics (except rubberized
fabrics), Polypropylene Carpet Backing, Non-Wovens, Tire Cord Fabrics,
and Felts.
-------
DRAFT
CATEGORY AND PROCESS DESCRIPTIONS
Category 1 - Wool Scouring
General Description. Wool scouring is conveniently separated from
other segments of the textile industry because of its uniqueness. Raw
wool (grease wool) must be wet processed to clean it before the fiber
may be dry processed to produce fiber, yarn or fabric for the further
wet processing steps found in a finishing plant. Neither cotton nor the
synthetic fibers require this initial wet-cleaning. Furthermore, most
wool scouring mills are geographically separate from other textile
operations. Exceptions exist where wool scouring is physically separated
from, but shares the waste treatment plant with, finishing mills.
The grease wool contains 25 to 75 percent non-wool materials, consisting
of wool grease (a recoverable material of some economic value) and other
excretions and secretions of the sheep such as urine, feces, sweat and
blood, as well as dirt consisting of both soil and vegetable matter.
Additional materils that may be present are insecticides (sheep dip),
and fugitive dyes used for identification. This variability in yield
and in the composition of impurities and grease causes a correspondingly
large variability in raw waste loads.
The wool grease constitutes a special problem in treatment since it does
not appear to be readily biodegradable unless it is well-emulsified so
tha-t bacteria can reach it. Therefore, the grease recovery step is
important to reduce pollution.
The 1962 Census indicates that this industry consists of 68 mills in SIC
2297, Scouring and Combing Mills. Category 1 scour mills include those
that scour or scour and comb, but not those that only comb, which is a
dry process. We estimate that of these 68 mills, less than half fall
into Category 1.
25
-------
DRAFT
The geographic distribution given in the 1967 census is as follows:
Number with Less
Mill than 20 Employed
Northeast Region: New England Div. 35 18
Middle Atlantic Div. 17 10
South Region: South Atlantic Div. 6 6
West South Central Div. 6 3
Not Allocated 6 _2_
Total 68 39
The 68 mills produced $89.9 million worth of goods in 1967, compared to
a value of $6.6 million for the scoured wool alone, indicating that
about 10 percent of the wool produced from both scouring and combing
mills is accounted for by Category 1 Mills, wool scouring. We estimate
that 21 mills do scouring alone, with geographic distribution as
follows:
Massachusetts - 6
Rhode Island - 3
Connecticut - 1
South Carolina - 3
Virginia - 2
Pennsylvania - 2
Illinois - 1
Texas - 3
Total IT"
Most small mills are connecting, or are connected, to municipal treating
systems. The larger mills are treating their own wastes, with the
exception of Wellman in South Carolina which is connecting to a
municipal system. Two large Burlington mills treat wastes combined from
carpet and woolen broadwoven fabric finishing plants, respectively.
As a guide to municipal/private treating systems, a report prepared by
the Wool Manufacturers Council of the Northern Textile Association is
included in the Appendix. It includes both Category 1 mills. Wool
Scouring, and Category 2 mills. Wool Finishing. Excerpts are given
below:
26
-------
DRAFT
Mills Responding 29
Municipal Systems 21
Private Systems 7
Not Sure 1
RAPP data for Region 1 indicates that 74 percent of the mills in this
category have no treatment and 26 percent have secondary treatment; and
none is tied to a municipal system. Since the time the RAPP data was
collected, many of the "nones" have added treatment systems. (Mills
discharging wastes to a municipal treatment system would not normally be
included in the RAPP data.)
Process Description. A generalized flow diagram of the wool
scouring process is shown in Figure IV-1.
Scouring consists of sorting the fleece and feeding it to a hopper. The
fleece is wet with fresh water in the first bowls. The wool then is
carried through a series of scouring bowls where scour liquor flows
countercurrent to it. Detergent is added in the third or fourth bowls
to emulsify the greases and oils. The scoured wool is then dried. In
mills where the cleaned wool is converted into top wool, the wool is
combed and drawn and sometimes air washed to remove the short fibers
(used for wool yarn) from the long fibers (used for worsted yarn).
In the scouring bowls, the heavier dirt and grit settles to the cone-
shaped bottoms where it is blown down once an hour or so, and carried to
the treatment plant by scour liquor.
The scour liquor, after picking up the soluble and less heavy dirt and
grit, is piped to a separation tank where further settling of dirt and
grit occurs. This material is also blown down and carried to the
treatment plant once a day, or more often if the dirt content of the
wool is high.
From the separation tank the scour liquor is processed to break the
emulsion and recover the wool grease. Two methods are commonly used to
do this: centrifuging and acid-cracking.
In centrifuging (as shown in Figure IV-1) the top low-density stream
contains concentrated grease, which is further dewatered in additional
Centrifuges to yield the recovered, unrefined wool grease. The medium-
density stream is combined with the relatively clean bottoms from the
auxiliary centrifuges and recycled to the wool scouring train as fresh
scour liquor. The high-density-bottoms stream consists mainly of dirt
and grit, and is sent to the treatment plant.
27
-------
UL.
Source: "ChemicarPhysical and Biological Treatment ot Wool Processing Wastes," by Hatch, et a!. 28th Annual Purdue Industrial
W;:!>;e Conference, West Lafay(;tte, Indiana, 1 May 1973.
FIGURE IV--1 CATEGORY 1: WOOL SCOURING
D
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DRAFT
An alternative means to break the grease emulsion for wool grease
recovery is the acid-cracking grease recovery system, also shown in
Figure IV-1. Sulfuric acid is added to the scour liquor and the mixture
is heated to break the grease/water emulsion. The grease is separated
from the liquor in a settling tank and recovered. The liquor is then
treated with lime to neutralize the acid and subsequently passes through
the waste treatment plant. Refer to Figure IV-2 for a typical material
balance on grease.
In the centrifugal method, about 60 percent of the grease is recovered:
the remaining 10 percent is attached to the dirt and grit. Centrifuging
recovers over 90 percent of the grease from the scour liquor. In the
acid-cracking method, pilot plant performance indicates a 98 percent
recovery of grease from the degritted liquor. No data is available to
indicate the initial split of grease between the grit and the raw liquor
from the grit settling tank.
Grease yield, in total, is 8 to 15 percent by weight of the greasy wool,
and this constitutes 50 to 65 percent of the wool grease initially
present. (Ref. 141). Note that 1-3 percent of the wool grease present
in the grease wool is allowed to remain on the wool as a conditioner.
Also, alkaline scouring has been used in which soda ash is added to the
wash water. The soda ash combines with some of the wool grease to form
a natural soap, thereby requiring less detergent but also lowering
recovered wool grease yield.
Objections to recycling the scour liquor have been voiced by industry
but appear to present no significant problem.
Some "raw" wools, mostly the Australian and New Zealand wools, are pre-
scoured at the source. However, this fact does not appear to signi-
ficantly affect this analysis of U.S. raw wool scouring mills.
Note that scoured wool is often converted into "tops" at the same mill.
In this operation, the short fibers are separated mechanically from the
long ones; the long fiber "tops" are used for worsted yarn and the short
fibers are used to blend into woolen yarns. No added pollution occurs,
but the water load is increased slightly by water washing to the air
from an air washing step. The guidelines developed for Category 1 are
based on the total product fiber and include both short fibers and tops.
Category 2 - Wool Finishing
29
-------
u
RAFT
1 00 lb. Grease
On Grease Wool
>_
•
Scour
>>_
»•
3 lb. Grease On
Scoured Woof
97 lb. Grease In
Scour Liquor
Grit
Settling
>»
*
^ 58.2 lb. Grease
Recovered
33.8 lb. Grease To
Waste With Grit
FIGURE IV-2 TYPICAL MATERIAL BALANCE: WOOL GREASE
-------
DRAFT
General_Descript.ion. This industry consists of many small mills —
most of them in the North (New England, New York and New Jersey) and
most acting like commission houses — and about 25 larger mills, mostly
in the South (Virginia, the Carolinas and Georgia).
The industry contains about 310 mills in Sic 2231 according to census
figures. Of these about 100 are involved in wool dyeing and finishing,
with the remainder being greige goods mills.
Most small mills do commission dyeing, and even the larger mills that
are part of the larger corporations commonly perform commission dyeing.
Commission dyeing operations imply a wide range of fabrics and finishes
as well as fiber types.
Probably not more than five mills still do more than 50 percent wool and
wool belnds: the rest process primarily other fabrics.
The 1967 Census figures for SIC 223, wool manufacturing and finishing,
indicate 310 mills total. These were distributed geographically as
follows:
Northeast Region:
North Central Region:
Southern Region:
Western Region:
Total
The geographic distribution of finishing mills
follows:
70S
7%
n%
_6S
100%
alone is estimated as
California 2
Connecticut 1
Georgia H
Illinois 2
Maine 3
Mas sachu se tts 11
New Hampshire 1
New Jersey 7
New York 13
North Carolina 8
Ohio 1
Pennsylvania 12
Rhode Island 19
South Carolina 5
Tennessee 2
Texas 2
Vermont 1
Virginia U
Wisconsin 1
As a guide to municipal/private waste treatment, a report prepared by
The Wool Manufacturers Council of the Northern Textile Association is
included in the Appendix. It includes both Category 1 mills. Wool
31
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DRAFT
Scouring, and CAtegory 2 mills. Wool Finishing. Excerpts are given
below:
Municipal treatment 21
Private treatment 7
Not sure 1__
Total mills responding 29
RAPP data for Region 4 indicates the following:
Municipal treatment
Private, secondary treatment
No treatment
100%
Since RAPP data is for mills discharging to navagable waters, the figure
given in the "municipal" category is not necessarily valid.
Nevertheless, these figures indicate the northern mills are
predominantly on municipal systems while most southern mills have
privately-owned treatment plants.
The processes of carding and spinning wool into yarn, and subsequent
weaving or knitting into fabric are included in Category 3, Greige
Mills.
Yarns made from wool are classified into either woolen yarns or worsted
yarns. Woolen yarns are characteristically of loose construction and
composed of relatively short fibers; worsted yarns are of tight
construction with few protruding fiber ends and composed of selected
long fibers (tops). As a result, worsted yarns are stronger.
wool finishing has been differentiated from other finishing categories
because of its (1) predominant use of chrom-type dyes and (2) high water
usage per pound of product.
As previously mentioned, however, few of today's wool finishing mills
process all wool. Many of the woolen mills by name handle 20 percent or
less wool with the balance being woven and knit synthetics. Also,
32
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DRAFT
within the 20 percent or less portion, woolen/synthetic blends (most
often with polyester) usually constitute the bulk of the fabric.
The high water usage appears to be caused by the fulling operation
(peculiar to 100 percent wool fabrics) and by the fact that most wool
and wool blend fabrics are more expensive than fabrics of other fibers,
and the higher quality necessitates more washing to reduce crabbing
(rubbing off of color). In addition, in Greige goods manufacturing, 100
percent woolen yarns sometimes have size applied to the warp yarns to
reduce loose ends during weaving, but few 100 percent woolen yarns, no
worsted-woolen blends, and worstedsynthetic blends have size applied.
Because of the low percentage of wool actually processed in mills today,
and the small amount of sizing used, this category appears in most ways
similar to category 5, Knit Finishing.
Variations occur in processing, similar to other finishing categories,
in that some fabrics are woven or knit from yarns that are already dyed,
either in the fiber or yarn form. A given mill may dye and finish part
of its production while only finishing the remainder. This variation is
unpredictable and is assumed to be included in the spread of data
obtained.
Process Description. The wool finishing process is depicted in
Figure IV-3. The three distinct finishing processes are shown as stock,
yarn and fabric finishing. Because the pollution generated by the
fabric finishing operation is similar to that generated by the other
two, fabric finishing is included in this discussion. If the greige
goods are 100 percent wool, they are first cleaned of vegetable matter
(and cotton fibers) by carbonizing (soaked in strong sulfuric acid,
dried, crushed and the char separated from the cloth), and then cleaned
of spinning oils and any weaving sizes by a light scour (detergent
wash). The 100 percent woolens are then dimensionally stabilized,
principally by "fulling," or mechanical working of the wet fabric in the
presence of detergents, to produce a controlled shrinkage or "felting."
Worsteds and most wool-synthetic blends are not fulled. (Worsteds are
hard, tightly-woven and dimensionally stable as received at the
finishing plant; woolens are loosely-woven, soft and often are firmed up
by fulling.)
The fabric is then dyed in batches in vessels called becks, washed in
the same vessels, and taken to dry finishing operations. The only dry
finishing operation of concern to water pollution is mothproofing.
The wet unit processes are described below in more detail.
33
-------
/
A
i
Bleach and
Rinse
Light
Scour
\
Dye
Wash
\
Ail
I Yarn Dyeing /
I :—H. '
LW = Liquid Wastes
Mechanical
Finishing
- Shear
- Press
Special
Finishing
e.g.
Mothproofina
= Solid Wastes
' 1
FIGURE IV-3 CATEGORY 2: WOOL FINISHING
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DRAFT
Light Scour. When greige goods are to be finished in the finishing
plant, they are usually cleaned as a first step. This cleaning consists
of washing with fresh water and detergent. The waste load consists of
the ^detergent plus the oils and any sizes that were added to the
material for lubrication in spinning, and for strength in weaving. When
synthetic size i used, the BODS consists entirely of the spinning oils
and the detergent.
Although the quantity of size varies somewhat, since it is put on the
warp yarns only and the warp ratio varies, very little size is used in
this category now. Therefore, the inaccuracy that arises from ignoring
this variation is very small in view of the overall waste load of the
finishing plant.
When the fabric is knit instead of woven, sizes are not used. However,
the knitting oils and detergent used for light scouring remain as
contributors to the waste load.
Carbonizing. Carbonizing consists of soaking the fabric in strong
sulfuric acid, squeezing out the excess, and then heating the wet fabric
in an oven. The hot acid reacts chemically with vegetable matter and
any cotton fiber contaminant and oxidizes these contaminants to gases
and a solid carbon residue. The fabric is then passed between pressure
rolls where the charred material is crushed so that it may be separated
by mechanical agitation and flowing air. A solid waste is produced, and
the acid bath is dumped when it becomes too contaminated for further
use, about once every two days.
Fulling. Fulling is usually used on 100 percent woolen fabrics but
not usually on woolen/polyester blends and not on worsteds. Since this
operation stabilizes the dimensions of the wool by "felting" it, the
blends usually do not need it, nor do the worsteds, since they are a
very tight yarn and weave to begin with. Fulling is accomplished by
mechanical work performed on the greige goods while they are in a bath
of detergent and water. Detergent is added as needed but no effluent
occurs until the following washing step. This is true of both "dry" and
"wet" fulling except that in the "wet" fulling, the water bath is dumped
about once every 2 to 3 days. In "dry" fulling, just enough water is
picked up by the fabric to lubricate it so the fabric is not standing in
water between its turn in the fulling device.
The fulling is followed by extensive rinsing to prevent rancidity and
wool spoilage. This step produced over 50 percent of the hydrauli^c load
in an all-wool mill we investigated. The necessity for the
extensiveness of
35
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DRAFT
Crabbing. Crabbing is the name given to the operation used to align
the fabric rectalinearly. Since the fabric comes in wet and goes out
wet, no effluent of significance occurs.
Pre-Scour. The pre-scour step is a final cleaning of the greige
goods prior to dyeing. Often, if a light scour or fulling is performed
before dyeing, the pre-scour step is not used. On sensitive dyeings,
however, both light scour and pre-scour are sometimes used. Detergents
and wetting agents are added. This and subsequent dyeing and rinsing
steps are performed in becks, commonly with a 20 to 1 water-to-cloth
weight ratio.
Dyeing. In the dyeing process, the fabric is dyed in atmospheric
becks or pressure becks. Pure wool fabric is dyed only in atmospheric
becks, but blends (mostly with polyester) are dyed in either atmospheric
or pressure becks. Knit woolen blend fabrics also are dyed in either
atmospheric or pressure becks, but most often they are dyed in jet
becks, a variation of the pressure beck that is supposed to reduce
physical damage to the knits.
In conventional becks the fabric is sewn into a long tube that
alternately soaks in a tube and then is pulled up and over a large
diameter slatted wheel, in a jet beck, the fabric is pulled up and put
back in the tub by the action of the dye liquor being pumped through a
venturi and carrying the fabric with it. Pressurizing of becks is
desirable for dyeing the polyester portion of the fabric, since little
or no carrier need be used. At atmospheric pressures large quantitities
of carriers are required to swell the polyester fiber and enable the dye
molecules to penetrate.
In the dyehouse becks, the operation usually consists of filling the
beck with water and a detergent for scouring (pre-scour, described
above). The scour water is dumped and the beck is refilled with water
and a wetting agent. After the fabric is wet-out, and the temperatures
raised somewhat, the dyestuffs are added and the beck brought up to
temperature (212°F in atmospheric becks, higher in pressure becks).
After 2 to H hours, 90 percent or more of the dye is exhausted, and the
dye bath is discharged to the sewer. This dye step is followed by a
clear water rinse. Since the dyes are very expensive, effort is made to
assure as high an exhaustion level as possible.
Blends are sometimes dyed in a single bath, sometimes in two separate
baths. Therefore, the hydraulic load can increase by 50 percent in the
case of two baths (including a rinse step after all dyeing is
completed).
36
-------
DRAFT
The more commonly used dyes for wool (or the wool in wool blends) are
metallized dyes and top and bottom chrome dyes. Others used include
reactive dyes, mill dyes, and others used for special effects. Use of
chrome dyes is diminishing since their high fastness is superfluous in
wool blends, given the lower fastness of the dyes used for synthetic
fibers. When wool and synthetic fibers are blended, therefore, non-
chrome wool dyes of fastness equivalent ot that of the synthetic fiber
dyes can be used in the interest of economy.
Rework levels appear to be 3 to 4 percent of total production. When
goods are reworked, they are either redyed to a darker shade, or
stripped with reducing chemicals, rinsed and redyed.
After it is dyed, the fabric is rinsed with clear water (up to four
rinses for some dyes).
Finishing. After it is dyed and rinsed, the fabric is removed from
the beck and, when used, soil repellants and other finishing agents are
padded onto it. Next, the fabric is dried and any subsequent dry
finishing operations — principally shearing (solid waste) and pressing
(steam condensate) — are performed.
Government fabrics of wool or wool blends must be mothproofed with
Mitten-FF. Dieldrin no longer is used because of its high toxicity.
Spillage appears to be the only way this material might find its way
into the waste waters.
Any of the finishing chemicals can appear in the waste when the padding
equipment is dumped and washed.
Category 3 - Greige Mills
General Description. Greige mills generally manufacture yarn and
unfinished fabric. Category 3 applied to woven greige goods, and greige
yarn production. However, knit grege goods production is almost always
combined with a finishing operation and therefore may be included in the
knit finishing category. The 1967 Census of Manufactures lists 1173
weaving mills (SIC 2211, 2221 and 2241) excluding wool, but some of
these are integrated weaving and finishing mills which belong in
category 4. Only 384 mills report water usage.
We estimate that there are 600 to 700 greige woven mills, 80 percent of
which are in North Carolina, South Carolina, Georgia, Alabama and
Virginia. Perhaps 20 percent of the 600 have their own waste treatment
plants, with almost all the rest disposing of wastes at municipal
37
-------
DRAFT
facilities. Less than 5 percent is believed to dispose of their wastes
in waterways without treatment.
Process Description. Weaving textile yarns into a fabric requires
application of size to the warp yarns in order to resist the abrasive
effects of the filling yarns as these are positioned by the shuttle
action of the loom. Greige mills apply the size and complete the
weaving. A many operate as completely independent facilities. Figure
IV-U shows opera
tions generally performed at a greige mill.
A typical sizing formulation is composed of a film-forming material, a
fatty or waxy component, and water. In some formulations, a water-
soluble dye may be used to give the grey cloth an identifying color, A
preservative may be used in some sizing mixtures.
The most common film forming materials are starch, polyvinyl alcohol and
carboxymethyl cellulose. Other sizes, such as polyacrylic acid and
styrene-maleic anhydride polymer, are used occasionally in weaving
special cloths.
Starch is a traditional sizing material, but in the past several years
the volume of polyvinyl alcohol used in the textile industry has
increased substantially, since starch does not adhere well to the
synthetic hydrophobic fibers. In many cases, mixtures of starch and
polyvinyl alcohol are used.
When formulations based on starch are used, the add-on of size amounts
to 10 to 15 percent by weight of the fabric, when polyvinyl alcohol is
used, lower add-on, 3 to 8 percent by weight of the fabric, is typical.
The range of add-on depends on cloth construction factors such as warp
yarn diameter, "tightness" of the fabric, etc.
The size formulation is applied to the warp yarns on a slasher. In this
machine, the yarns are drawn through the size bath, squeezed to give the
desired add-on, and then dried by passage over a series of hot drying
cans. The dry yarns are wound on a warp beam and are ready for weaving.
Weaving is a dry operation, but is normally done in buildings maintained
at high humidity. Under these conditions, the size film is flexible,
and yarn breaks on the loom are minimized. Yarns sized with polyvinyl
alcohol may be woven at a somewhat lower humidity than yarns sized with
starch. As indicated in Chapter V, cooling and humidifying water used
in a greige mill represents a substantial portion of the total water
usage.
38
-------
o
Opening and
Picking
1
SW
mm
•>
Carding and
Spinning
1
SW
X
Polyester ^
k. J
Blend
Cotton
Polyester
Woven
Fabrics
To Yarn Dyeing and
Finishing (Cat. 7)
To Woven Fabric
Finishing (Cat. 4)
To Knit Fabric
Finishing (Cat. 5)
To Woven Fabric
Finishing (Cat. 4)
To Yarn Dyeing and
Finishing (Cat. 7)
= Solid Waste
LW 1 = Liquid Waste
FIGURE IV-4 CATEGORY 3: GREIGE GOODS
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DRAFT
Category 4 - Woven Fabric Finishing
General Description. This category encompasses mills which finish
woven good (or integrated greige goods and finishing mills). Mills that
finish a variety of textile materials, including some yarn and knit
goods, and commission houses are included in category 4. 600 mills may
fall into category 4. About 20 percent treat their own waste, that
waste from about 75 percent enters municipal systems, and that 5 percent
have no waste treatment.
This category predominates in the Southeast (North and South Carolina,
Georgia, Virginia, Alabama), but there are some large operations in New
York and New England.
Process Description. Wet processes which are used in finishing
woven greige fabric may be divided into two groups: those used to remove
impurities, clean or modify the cloth; and those in which a chemical is
added to the cloth.
The first of these groups includes desizing, scouring, bleaching,
mercerizing, carbonizing and fulling. Only cotton and cotton blends are
mercerized. The last two of these processes are used only on wool and
wool blends (See category 2.)
The second group of processes includes dyeing, printing, resin
treatment, water proofing, flame proofing, soil repellency and a few
special finishes whose use represents a very small proportion of the
total.
Certain fabrics, including denims and some drapery goods, are "loom
finished." In production of these goods, the warp yarns are dyed, woven
to a fabric, and the fabric finished with a permanent size. For these
fabrics, the first group of processes listed above (cleaning and
preparing the cloth) is avoided entirely. For this reason, mills
producing this group of fabrics may be a subcategory, although we have
not treated it as such. The degree of finishing necessary to provide
fabric ready for sale depends significantly on the fiber(s) being
processed. The natural fibers (cotton and wool) contain substantial
impurities, even after they have been woven as greige goods, and require
special treatments to convert them to the completely white, uniformly
absorbent form that is essential for dyeing, resin treatment, etc.
Synthetic fibers contain only those impurities that were necessary for
manufacture of the fiber and spinning to obtain yarn.
-------
DRAFT
The different operations listed above have been described in the litera-
ture, and the contribution of each to wastes has been discussed. For
convenience, a flow sheet for woven fabric finishing is given (Figure
IV-5), and details about each process step are given below.
Desizing. The sizes (see Category 3) are removed completely from
the greige fabric. Enzyme or sulfuric acid is commonly used to aid in
dissolving the starch in water. When enzyme desizing is practiced,
sodium chloride and a surfactant are frequently added to facilitate the
process.
After the desizing agent has been applied, the goods are placed in a bin
or a steamer to provide the residence time required. Residence times in
storage bins are typically 12 hours or more. If elevated temperatures
are used (by employment of J-boxes or steamers) the residence time is
reduced to a few minutes at 210 or 212F or 30 minutes at 180F. Finally,
the goods are washed with water to remove the decomposed starches from
the fabric.
For desizing of polyvinyl alcohol and carboxymethyl cellulose, materials
which are directly soluble in water, no decomposition is required. The
goods are merely washed with water at 180F or higher on washers without
the use of steamers, J-boxes, or padders.
Scouring. Scouring is done to remove much of the natural impurities
of cotton, using 2 to 3 percent sodium hydroxide; phosphates, chelating
agents and wetting agents may be used as auxiliary chemicals. The
synthetic fibers require much less vigorous scouring; sodium carbonate
and a surfactant may suffice. In the case of cotton/synthetic blends,
Varsol may be used in conjunction with the aqueous scouring liquor.
The operation known as kier boiling is often employed to scour desized
cotton and cotton/polyester woven fabrics. The kier is a large vertical
cylindrical pressure vessel which can hold up to several tons of fabric.
The goods (in rope form) are plaited into the kier by the kier plaiter,
the cover is installed, and the scouring chemicals are recirculated
through the goods and an external heat exchanger for temperature
control. An aqueous mixture of sodium hydroxide, soap and sodium
silicate is employed at temperatures of 220 to 250F and pressures of 10
to 20 psig. The goods are scoured for 6 to 12 hours. The kier is then
cooled by recirculation of cooling water and the goods are displacement
washed. In certain instances, difficult fabrics are double-scoured.
The scouring step is designed to remove fats, waxes and pectins from the
wpven fabric.
-------
Water,
Enzymes or
H2S04
Finishing
Agent, e.g.
Starch,
Resin
I'-
LL.
QZ
Q
FIGURE IV-5 CATEGORY 4: WOVEN FABRIC FINISHING
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DRAFT
Certain heavyweight fabrics normally are not processed in rope form as
required for kier boiling since creases result in streaks in subsequent
dyeing steps. These goods are therefore processed in an open-width
boil-out machine, also known as the progressive jig. The jig is loaded
with a scouring solution and the goods are fed through continuously by
the use of 8 or 10 transfer rolls. The system is heated with steam
coils and the temperature and residence time are maintained for proper
scouring of the goods. The goods are wound onto rolls in the machine
and maintained in contact with scouring liquids for the necessary
period. Then they are unrolled through wash boxes and folded into a
cloth truck or onto a roll.
The scoured cotton may be used directly for producing dark shades or may
be bleached by padding through hydrogen peroxide solutions, and
subsequently washed, neutralized, and dried before dyeing.
Mercerizing. Mercerizing is one of the more important operations
conducted in the preparation of woven cotton and cotton/polyester
fabrics prior to dyeing, printing, and finishing.
In mercerizing the woven goods are immersed in 15 to 25 percent
solutions of sodium hydroxide and a penetrant. This treatment increases
tensile strength, increases surface luster, reduces potential shrinkage
and increases the affinity for dyestuffs.
Physically, mercerization swells the cellulose fibers as alkali is
absorbed into them, with higher concentrations, longer residence times,
and lower temperatures favoring greater swelling. The mercerization
step is conducted with the fabric either under tension or in the slack
condition, with tension mercerizing favoring increases in tensile
strength and slack mercerizing favoring increases in abrasion
resistance.
Mercerization may be done on greige goods (after desizing), on scoured
goods (after kier boiling or caustic treatment in a range) or on
bleached goods. More complete mercerization results from treatment of
bleached fabrics (in terms of fiber swelling), but mercerization of
greige goods or scoured goods results in greater tensile strengths.
Mercerization is normally conducted continuously; the operation consists
of the following steps:
(a) A scutcher and water mangle are employed to open the goods
from the rope form, and a mangle is used to dewater the
goods to a uniform moisture concentration.
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DRAFT
(b) A multiple-contact saturating operation is conducted usually
with three saturating bowls. The goods are fed through the
system continuously which provides sufficient residence time
and contact to completely saturate the fabric with caustic
soda solution.
(c) Timing cans are employed to increase the residence time
of the fabric in the sodium hydroxide solution.
(d) A tenter frame is employed to maintain the fabric under
tension as the fabric travels through the system and the
actual mercerization of the cellulose takes place.
(e) At the end of the tenter frame is a washing system that
includes water sprays, vacuum units and wash water heaters
and re-circulators to wash the fabric and reduce the caustic
content while the fabric is still under tension in the
tenter frame.
(f) The fabric is given a final wash in the recuperator, which
removes the remainder of the sodium hydroxide from the
fabric and reduces the residual pH to an acceptable level
(i.e., 8.5).
Bleaching. Cotton and cotton blends normally are bleached with
hydrogen peroxide. Other chemicals generally employed in the process
are sodium silicate, trisodium phosphate, a surfactant, and a chelating
agent. In bleaching some synthetics, chlorite may be used.
In order to improve product uniformity and increase throughput,
continuous bleaching ranges are employed for the majority of the cotton
and blended woven goods. The goods are fed in either rope or open width
form (or in combinations) and, in certain cases, the desizing and
scouring operations are placed in tandem with the continuous bleaching
range. The following process units constitute a typical, continuous
peroxide bleaching range, using J-boxes for storage:
Washing. The goods are washed, using either open width or rope
washers to ensure removal of converted starches from the desizing step.
Caustic Saturator. As the goods continuously leave the washer they
are squeezed through rolls to a minimum water content and then saturated
with sodium hydroxide solution in additional squeeze rolls. The goods
may be in either rope or open width form, but must remain in the
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DRAFT
saturator long enough to permit, them to become completely saturated with
sodium hydroxide solution.
Caustic J-Box. The goods are then fed contiuously to the caustic J-
box, whose function is to saturate the cloth for the necessary length of
time at the desired temperature (205-210F). The throughput of the J-box
is controlled to provide a residence time ranging from 40 minutes to one
hour, resulting in saponification of natural fats and waxes carried in
the cotton.
Caustic Washers. The caustic solution is then removed from the
fabric by countercurrent washing, usually with large quantities of hot
water to ensure complete removal.
Peroxide Saturator. The peroxide saturator is similar to the
caustic saturator. It contains a solution of hydrogen peroxide and
sodium silicate in sufficient concentrations to retain 1.5 percent of
the hydrogen peroxide and 1.5 to 3 percent of the sodium silicate based
on the dry weight of goods.
Peroxide J-Box. The design and operation of the peroxide J-box is
the same as for the caustic j-box. The unit is operated at about 200F,
with a residence time that varies from 40 minutes to 1 hour to bleach
the fabric.
White Washes. The bleached goods are now washed to final purity
before piling into bins or going directly to the dryer. Hot water is
preferred for washing, but cold water is employed in certain instances.
Flow meters are employed to regulate the flow of fresh water, and
countercurrent conditions are maintained.
In certain instances, two stages of bleaching are operated, sometimes
with sodium hypochlorite in the final stage.
Hypochlorite Saturator. The hypochlorite saturator is similar to
the caustic and peroxide saturators. Its purpose is to apply a solution
of sodium hypochlorite to the fabric to complete the bleaching
operation. The solution is maintained at room temperature and the
quantities are continuously monitoried in order to control the bleaching
operation.
Hypochlorite J-Box. The operation of the hypochlorite J-box is
similar to those discussed before, except that it is operated at ambient
temperatures. Residence times are similar to those employed in peroxide
.bleaching, and the same unit may be employed for hypochlorite and
peroxide bleaching at different times.
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DRAFT
Washers. Two washers are normally required to neutralize and wash
the goods after hypochlorite treatment. At least a portion of the
first washer is used to apply sodium bisulfite or sulfur dioxide
solutions to neutralize excess bleaching chemicals.
Steamers. In open width bleaching ranges, steamer units may be used
instead of J-boxes to store goods after they have been impregnated with
caustic or bleaching solutions. These are particularly useful in
processing heavyweight fabrics.
Small Open Width J-Boxes. More recent bleaching technology employs
more concentrated solutions and more drastic operating conditions and
has resulted in the development of the small open width J-box which
permits effective bleaching with residence times of only 10 to 15
minutes.
Continuous Pressure Scouring and Bleaching. The newest type of
steamer for bleaching ranges is an enclosed type with pressure locks and
seals. This enables the steamer to be operated as a pressure vessel and
the reaction time for the chemicals is reduced from 40 minutes to only
one or two minutes. The treatment of fabrics is a function of time,
temperature and concentration. The increased temperatures made possible
by pressure steamers reduce the time needed for complete chemical
reaction.
The problems associated with equipment designed for operation at 25 psig
and for continuous entry and removal of continuous webs have posed a
substantial design problem. However, several machines are now available
with satisfactory sealing devices, so they may perform well at these
pressures. Some of these units utilize rolls as a sealing mechanism and
others have developed a system involving a lip seal. In addition there
are reports of pressure steamers which may be operated at pressures up
to 45 psig and develop temperatures of 292F, resulting in residence
times only of one or two minutes.
Sodium Chlorite Bleaching. Although sodium chlorite bleaching has
had very little economic success in the bleaching of pure cotton goods
over the years, its use in kier steamers and becks is now receiving more
attention since many of the man-made fibers are sensitive to bleaching
and can be bleached successfully with sodium chlorite. It is now used
to a considerable extent either alone or in conjunction with other
bleaching agents for preparation
Dyeing. Dyeing is the most complex of all textile finishing
processes. Table IV-3 shows the dyes used in the textile industry, the
46
-------
o
Table IV-3
Types and Amounts of Dyes Used in the Textile Industry
/
Amount
*
Poly-
Poly- ester Nylon/ Used'
Acrylic Cotton Wool Acetate Rayon ester PE/cotton Nylon Cotton %
Dye Types
Acid / ,/ 10
Azoic y y 3
Aniline Black x/
Basic (Cationic)
Developed
Dyeblends
Direct \/ y^ ^ *s 17
Disperse y / ^- ^- ^ 15
Fiber-reactive v 1
/ V/ v''' v/ v^
Fluorescent ^ 1
Indigo v/ s/ _
Sulfur ' v/ v/ v/ 10
Vats V7 xX ^ 26
Natural ^
Oxidation Base
Mordant
Approximate percent of total textile use. Usage of dyes for which amounts are not shown totals
approximately 10 percent (not including dye blends).
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DRAFT
fibers they are generally used to color, and the relative amounts of
each dye used by the industry.
When textiles are dyed, an excess of the dyestuff is used, and other
chemicals are used to help deposit the dye, or to develop the color.
Dye loadings vary widely even with a particular dye class, depending on
the weight of fabrics being treated and the depth of color desired. The
range of chemicals employed in dyeing also varies widely from place to
place and operation to operation, and depends substantially upon the
dictates of the marketplace.
Table IV-4 presents a summary of chemicals used in application of dyes
to textiles. Dyed goods are generally, but not always, washed and
rinsed to remove excess dye and chemicals from the cloth. Washing
involves use of a detergent, and also may involve the use of soda ash or
a sodium phosphate.
The chemicals used in dyeing may depend significantly on the dyeing
procedure which the fabric manufacturers fins appropriate. Both batch
and continuous dyeing are practiced, and both may be employed in the
same finishing plant.
Textile goods are dyed continuously when the demand for a single shade
is sufficiently high to justify the necessary equipment. Production of
denims, in which the warp yarns are dyed continuously, is one example;
no special chemicals are required as a result of dyeing continously. In
Thermosol dyeing, which is practiced on woven cotton (or rayon)/
polyester blends, a dye blend is padded on the fabric, which is then
dried and heated, washed, rinsed and dried. Thermosol dyeing requires
addition of a gum to the dye mixture, so that the formulation will
deposit uniformly on the cloth.
Piece dyeing, on runs which are not long enough to justify continous
processing, are normally performed in an open beck, operated at boiling
temperature, or in a sealed pressure beck, operated at about 250F. In
modern units, the entire dye cycle (including washing and rinsing) is
controlled automatically. Pressure becks have been found advantageous
use of less carrier; wastes are decreased correspondingly.
Printing. Printing involves application of dyes or pigments in the
form: of a pattern on to fabric. Dyes penetrate and color the fiber;
pigments are bonded to the fabric with a resin.
In general, the formulated print paste is applied to one side of the
fabric only.
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DRAFT
Vat, direct and other dyes may be printed; vats appear to predominate.
The same chemicals used for the regular dyeing process are used in
printing, but in addition, a thickener is used to give the mixture high
viscosity. Many thickeners such as gum arabic, British gum, alginates,
methyl cellulose and others have been used. Urea, diethylene glyool and
glycerol are frequently used in the formulations.
Pigment print formulations are more complex. The pigments are blended
with a resin binder (frequently melamine-formaldehyde), a latex, an
aqueous thickener, Varsol and water.
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DRAFT
Table IV-4
Chemicals Use in Application of Dyesl
Direct
Disperse
Sulfur
Acid
Cationic
Reactive
Auxiliary Chemicals Necessary
sodium hydroxide
sodium hydrosulfite
dispersing agent
hydrogen peroxide
acetic acid
sodium perborate
sodium dichromate
acetic acid
alternative
chemicals
sodium chloride
sequestering agent
orthophenyl phenol
butyl benzoate alternative
bisphenyl carriers
chlorobenz ene
acetic acid alternative
monosodium phosphate
dispersing agent
sodium sulfide
sodium carbonate
sodium dichronate
acetic acid alternatives
hydrogen peroxide
acetic acid
acetic acid
ammonium sulfate of
ammonium acetate
sodium chloride
acetic acid or
formic acid
sodium sulfate
sodium chloride
urea
sodium carbonate
50
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DRAFT
sodium hydroxide
Table IV-U (Continued)
Chemicals Used in Application of Dyesl
Dye^Type Auxiliary Chemicals Necessary
Developed developer
sodium chloride
sodium nitrite
sulfuric acid
sodium carbonate
[1ln addition to the chemicals listed, all of the dye types will
usually use a small amount of surfactant. After the dyeing has
been completed, the dyed goods are washed and then rinsed. Washing
will involve use of a detergent as well as soda ash and a phosphate. ]
Vat dye prints must be oxidized, with sodium dichrornate or other
oxidant, to develop the color. Steaming and brief aging aid in the
process. Pigment prints do not require chemical after treatment, but
must be dried and heated to insolubilize the resin-pigment mixture.
Printing a fabric that contains polyester may require a carrier in the
formulation.
Following complete application of the print mixture, the fabric is
washed thoroughly to remove excess color and chemical.
Special _Finishes {resin treatment, water proof ing ff flame proofing,
soi 1.. m release). Each of these finishes endows fabric with a particular
property desired by consumers. The property is indicated by the name,
except for resin treatment, which designates finishes that provide
wrinkle resistance. Several of the treatments may be applied from a
single bath.
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DRAFT
As would be expected for processes that provide such diverse effects,
the range of chemicals used is very broad. For resin treatment, a urea-
formal dehyde-glyoxa 1 compound ("DMDHEU"), a fatty softener, and a
catalyst (zinc nitrate, magnesium chloride) are used together. Water
repellents include silicones, fluorochemicals, and fatty materials, each
generally applied with a catalyst. Soil release treatments include
special acrylic polymers and fluorochemicals.
These finishes are generally applied by impregnation of the fabric
followed by squeezing to the desired add-on. The moist material is
dried and then cured by additional heat. The cured fabric is frequently
packed for shipment without rinsing. Most resin-treated goods are
subsequently cured in a garment factor and must not be rinsed, since the
catalyst would be removed.
Category 5 - Knit Fabric Finishing
General Description. The knitting industry is characterized by a
large number of plants and a structure organized along specialized
product segments. The major segments are knit fabric piece goods,
hosiery, outerwear, and underwear. The geographical distribution of
knit mills, SIC code 225, according to 1967 census data is as follows:
No.Plants
Northeast Region 1616
North Central Region 76
South Region 910
West Region 96
Total 2698
While the industry has shown substantial growth in value of shipments,
we estimate that through consolidation and other factors the current
number of plants in this industry is about 2500. Of this number, we
estimate that about 1100 plants have only dry operations. These are
plants such as sweater mills in the outerwear segment, which knit goods
from purchased or commission dyed yarns, or mills which have finished
goods dyed on a commission basis and therfore have no process water
requirements. Most of the sweater mills are located in the Northeast.
In those isolated instances where sweater or similar mills dye their own
yarn, these mills should be subject to category 7 guidelines.
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DRAFT
Of the 1400 plants believed to have wet process operations, we estimate
that 85 percent discharge to municipal treatment systems. The great
bulk of these are hosiery plants (700-800) located primarily in North
Carolina, Tennessee, an Pennsylvania. Census data on process water use
and discharge indicates that in 1968, 90 percent of the hosiery plants
discharged to municipal systems. The small number of isolated plants
which may not be tied to municipal systems should be subject to category
5 guidelines. Of the remaining wet process plants, we estimate 100 have
private waste treatment facilities and 90 have no waste treatment.
The knit fabric segment of the industry has about 540 plants. These
plants are the source of finished knit piece or yard goods for the
apparel, industrial, and household goods trades, and also serve to
augment supplies of fabric to underwear and outerwear manufacturers.
These plants are the main subject of category 5. The large knit fabric
plants are located mainly in North and South Carolina and Georgia, but
substantial numbers are also located in New York, and Pennsylvania.
The production of knit fabrics for women*s and men's wear has been the
fastest growing sector of the textile industry over the past decade.
Synthetic fibers are the predominant types used in knit goods except for
cotton goods produced for underwear and sleepwear. In the latter case,
however, polyester has been replacing increasing proportions of cotton
fiber. Plants which previously processed all-cotton are using greater
amounts of polyester and the trend is expected to continue.
Process Description. The wet processing operations performed in
knit fabric finishing are shown schematically in Figure IV-6. This
is necessarily a generalized flowsheet; the specific operations employed
in a given plant will vary from plant to plant. In general, the yarns
are purchased in the undyed state, with a knitting oil finish to provide
lubrication for the knitting operation. The amount of finish on the
yarn ranges from 1 to 7 percent depending on the type of yarn and fiber.
This is a significant difference from weaving yarns which are sized with
starch or other polymeric materials. After the yarn has been knitted
into fabric, the fabric may be processed by one or more of the
alternative routes indicated in Figure IV-6. The wet process operations
employed in a plant depend on the nature of the goods involved and the
end product requirements. Typically, knits are processed in piece goods
form. The fabric may be washed on continuous countercurrent washers
prior to loading the fabric in dye machines to remove knitting oils and
other contaminents, or washing may be the first step in the dye machine
cycle. Harm water with a small amount of added detergent is used. In
contrast, woven goods require more extensive treatment to remove starch
or polymeric sizes.
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= Liquid Wastes
Q
FIGURE IV-6 CATEGORY 5: KNIT FABRIC FINISHING
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DRAFT
The types of dyeing equipment generally employed include: atmospheric
becks, pressure becks, jet (atmospheric or pressure) becks, atmospheric
or pressure beam dyeing machines, and paddle type machines. Some plants
may also package dye a portion of their yarns.
The types of dyestuffs, auxiliaries, and conditions employed for dyeing
knit goods are essentially the same as for woven goods of comparable
fiber composition. See the discussion under category 4 for details of
the dyeing operation.
Some of the fabrics which are beam dyed are first wet batched. In the
wet batching operation, the fabric is passed through a dilute aqueous
surfactant bath at controlled temperature before being wound on a
perforated beam. Batching helps control shrink and yield, and also
enhances uniform penetration of dye liquors in the dyeing process.
There is some waste generation from the wet batching operation; a small
quantity of the dilute bath is dumped occasionally for cleanup and there
is a continual slow drain of water from the wetted fabric which contains
knitting and yarn lubricants.
In knit plant, finishing cotton fabric — e.g., for underwear and
sleepwear — wet process operations also include scouring and bleaching
in kiers or comparable equipment. Plants that process either cotton or
synthetic goods may also have fabric printing operations.(See discussion
under category H for details of these operations.)
Most knit fabrics are treated with softeners, and resin finishes, and in
some cases, with water and oil repellents. These finishes are applied
from a pad bath just prior to final drying and dry finishing operations.
These baths are discharged periodically as required for fabric lot or
formulation changes, but the total daily volume of discharges is very
small.
Category 6 - Carpets
General Description. Tufted carpets account for well over 65
percent of the plants and 86 percent of the dollar volume, and
constitute 71 percent of the employment in this industry. Therefore,
the guidelines are generated principally around this segment. About 70
percent of the industry is located in Dalton, Georgia and these mills
are connected into the municipal treating system. However, the
remaining carpet mills are of sufficient quantity to warrant effluent
guidelines.
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DRAFT
Tufted carpets consist of face yarn that is looped through a woven mat
backing (mostly polypropylene, some jute), dyed or printed^ and then
backed with either latex foam or coated with latex and a burlap-type
woven fabric backing put over the latex.
The dominant face yarn is nylon, followed by acrylic and modacrylic, and
polyester; the latter two groups in total are about equal to nylon.
Since dyeing of these fibers in carpets differs little from dyeing
fabric, the dyeing descriptions for these fibers given in other
categories applies here. Beck, continuous dyeing, and screen printing
are practiced.
The latex operational load on the waste treatment facility of an
integrated mill, after adequate pretreatment by coagulation, is
insignificant. Moreover, latex wastes are treatable by coagulation to a
level to meet recommended guidelines for this category. Therefore, all
wet processing carpet mills are covered in this category, including
latexing only, finishing only, and integrated mills.
Census data for 1967 indicates 385 carpet mills in total, and 50 of
these are wet processing. We estimate there now are 70 wet processing.
The distribution of the 385 mills is as follows:
Northeast Region 83 22%
North Central Region 13 3%
Southern Region 231 60%
Western Region 58 ^15ft
Total 385 100%
In 1970, the industry product mix looked like the following:
SIC Emp. Value of
Category. Descript.. No. Plants (thou) Ship, (mil)
2271 Woven 60 8.6 203
2272 Tufted 270 39.1 1914
2279 Other 85 5.3 98
227 All 415 53.0 2215
Since 1970, a significant number of woven carpet mills have either
closed or changed over to tufted production.
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DRAFT
In 1970, the face ,y§rri consumption was dominated by nylon, with
polyester, acrylic/modacrylic, and polypropylene of significance. The
use of wool and cotton, rayon or acetate has been shrinking rapidly with
the first mentioned group gaining. The following figures represent the
relative share of each fiber:
Material J
Nylon 44
Polyester 17
Acrylic/Modacrylic 16 Growing
Polypropylene 7
Wool 8
Cotton, Rayon Shrinking
Acetate, other 8
tSource: chase Report, op. cit.1
Since 1970, nylon has held its position. Acrylic/modacrylic has grown
but polyester, because of flammability problems, has declined.
In 1968 the Tufted Textile Manufacturers Association showed that about
45 percent of its members had their mills in Dalton, Georgia, with
another 37 percent in Georgia. The remaining 18 percent is scattered
through 11 states including Massachusetts, Texas, and California.
Many of the new mills are going into other states, principally
California and other far western states. The bulk of these newer mills
appear to be connecting into municipal systems.
Process^Description. carpets are yarn dyed, piece dyed, and
printed. When yarn dyed carpets are made, the yarn is often dyed in
another mill and brought to the carpet mill. (Yarn dyeing is covered in
category 7.) The relative quantities of yarn, beck, and continuous
dyeing* and printing and latexing may vary widely. (For instance, one
exemplary mill dyes or prints only 30 percent of its production.
The yarn is tufted onto a polypropylene or jute woven backing in a dry
operation (Figure IV-7). Following this, the tufted carpet can be
either
printed or dyed. If printed, a semi-continuous screen printing
operation is performed, followed by a wash and rinse step in the same
machine. If dyed, the most common method is beck dyeing, in a manner
quite similar to that described in previous categories for yard goods.
The industry claims a higher liquor-to-fabric ratio, however, because of
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Predyed Yarn
= Solid Waste
EJL.
ot:
Q
FIGURE IV-7 CATEGORY 6: CARPET MILLS
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DRAFT
the difficulty in making the carpet sink and become thoroughly
Many small air bubbles become entrapped in the tufts.
wetted.
The continuous dyeing appears very similar to the continuous pad-stream
process used for cotton/synthetic blends broad-woven finishing. After
it is dyed the carpet is dried in a tunnel drier. The carpet is then
ready for application of either a single or a double backing.
For the single backing, a continuous applicator applies a foamed latex
layer to the carpet's underside. In double-backed carpet, a layer of
unfoamed latex is applied in the same manner, and a final fabric backing
is pressed on, being cemented in place by the latex. In either case, a
liquid latex waste is generated. Some of the latex becomes hardened, so
a mixture of solid and liquid latex results. Some of this material is
collected by shovelling it into a barrel for land-fill disposal. The
rest is washed off by hosing and is usually conducted via a separate
conduit to a latex coagulation facility before the relatively clarified
liquor is sent to join the dye wastes for treatment.
Category 7^.- Stock and Yarn Dyeing and Finishing
General Description. Category 7 includes plants which clean, dye
and finish fiber stock or yarn. The plants may or may not have yarn
spinning facilities.
products.
Sewing thread, textile and carpet yarn are typical
We estimate that 750 plants in the country fall into this category.
Most (probably 80 percent) dispose of their wastes at municipal
facilities. We believe that 5 to 10 percent treat their own waste and
the rest have no waste treatment facilities.
About 60 percent of yarn dyeing and finishing is performed in Virginia,
North Carolina, South Carolina, Georgia and Alabama, with the remainder
distributed across the eastern U.S. and the Far West.
Process Description. The raw material for the plants considered in
this category is crude yarn obtained from a spinning facility. The yarn
may be natural, synthetic, or blended. The differences between
processing the natural and synthetic fibers have been discussed under
category U and are equally applicable to category 7, yarn processing.
Wet processes used by yarn mills include scouring, bleaching,
mercerizing and dyeing (Figure IV-8). The remarks made about each of
these processes
wnder category 4 apply to yarn processing.
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Cotton or
Cotton-Blend
Yarn o
Stock
= Liquid Wastes
FIGURE IV-8 CATEGORY?: STOCK AND YARN DYEING AND FINISHING
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DRAFT
Several techniques are available for processing raw yarn into the
finished product. The most common process is probably package dyeing,
but other processes, such as space dyeing, are widely used. In the
former process, yarn wound on perforated tubes is placed in a large
vessel, which is sealed. The dye solution, at an appropriate
temperature, is circulated through the yarn. The dyed yarn is washed,
rinsed and dried. In space dyeing, yarn i knit and the fabric is piece
dyed, washed, rinsed and dried. The fabric is then unravelled and the
yarn is wound on cones.
Category 8 - Special Products
Coated _Fabrics.. Polyvinyl chloride (PVC) coated fabrics dominate
coated fabric production included under SIC code 22. Rubberized, or
rubber coated, fabrics are specifically excluded from this code and are
assigned to SIC code 3069. WE estimate that PVC coatings account for 70
percent or more of total coated fabric production. These coatings are
applied as 100 percent "active solids" systems either as plastisols
(dispersion of polymer particles in liquid plasticizer) or as melts
(flexible grade polymer plus plasticizer). The plastisols are generally
coated by knife over roll coaters and the melts are applied by
calenders. A minor portion, estimated at 10 percent or less, or coated
fabrics is coated with polymer latices (PVC or acrylic). In this case
some dilute aqueous waste is generated from equipment wash-ups. These
dilute aqueous latex wastes should be subjected to the treatment control
described under category 6 to remove latex solids. Plastisol coating
and calendering of PVC coatings do not involve process water use.
Therefore, these plants are dry operations.
Polypropylene Carpet Backing. Polypropylene carpet backing is
produced by one of three basic methods: extruded film is slit and woven
into a web; polypropylene staple fiber is formed into a nonwoven web and
needled to provide mechanical strength; or continuous filament is melt
spun, directly deposited into a nonwoven web, and bonded with heat
(spunbonded process). None of these processes generates significant
process waste water. The woven slit film and theneedled nonwoven
processes are dry operations. The spunbonded process is a special
modification of conventional synthetic fiber production and should be
considered part of the synthetic fiber industry.
Tire Cord Fabric. Tire cord fabric plants prepare the cord fabrics
used in the production of tires. These plants purchase yarns and twist
and weave the yarns into a loose fabric structure. The fabric is then
dipped in a latex based bath and dried in what is referred to as a Z-
calendering operation. This treatment serves to prime the fabric to
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DRAFT
provide adhesion to the rubber during vulcanization of the tire. The
only process waste generated in these plants originates from occassional
wash-ups of equipment. Our assessment of RAPP data from a number of
these plants indicates that waste loads are extremely small. Since the
wastes are dilute lates, threatment technology of the type recommended
in category 6 should be employed to remove latex solids.
Dry Prpeess Nonwovens. Nonwoven webs made by so-called dry processes
(carded webs, air-laid webs, etc.) comprise the largest segment of the
nonwoven industry. While the webs are formed by a dry process, binders
are usually applied in the form of latex by dip, gravure roll, or spray
application. Acrylic polymer type latices account for about 80 percent
of total binders used. The binder formulations are conserved for use on
a day-to-day basis. However, some dilute aqueous waste are generated by
equipment wash-ups.
Based on our contacts with the three major producers in this industry,
the practice is to discharge pretreated waste to municipal systems. Of
the nine plants operated by these producers, seven discharge to
municipal systems. Pretreatment consists of settling (alum coagulation
employed in one instance) . Where required, pH control is also employed.
One of the plants discharges into a waste treatment plant which also
serves a large woven goods plant. No data is available on this nonwoven
plant. The one nonwoven plant identified as having its own waste
treatment facility, does not now have adequate provision for removal of
latex solids. In view of the limited data, and the similarity in the
nature of the dilute latex wastes to those generated in carpet backing
operations, we recommend that pretreatment and treatment technology
employed for removal of latex solids from carpet plant wastes be applied
to latex wastes from nonwoven plants.
Felts. Pelts are composed of fur, hair, wool and synthetic fibers in
various combinations. Synthetics are vastly predominant today. Felt is
a nonwoven material formed by physically interlocking fibers by a
combination of mechanical work, chemical action, moisture, and heat.
After felting, the felt is rinsed. If dyeing is performed, it is done
in the fiber form before felting. Oten the felts are finished with a
resin of the resorcinol/formaldehyde or acrylic type. All six felt
manufacturers who belong to the Northern Textile Association are dis-
charging waste into municipal sewers. Therefore, guidelines are not
proposed for this segment. Adequate pretreatment is performed by
neutralization and fiber removal.
SECTION V - WASTE CHARACTERISTICS
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Category 1 - Raw Wool Scouring
The raw waste from raw wool scouring is different from the waste from
all other categories used in this study: it contains significant
quantities of oil and grease, even after in-process recovery. The wool
grease is not readily biodegradable nor easily precipitated chemically
(Ref. *1«*3). In addition, sulfur is brought in with the wool, as well
as phenolic and other organic materials derived from the sheep urine,
feces, blood, tars, branding fluids and sheep-dips used as insecticides.
These items appear randomly in the effluent.
The detergent used to emulsify the grease constitutes about 10 percent
of the total waste load to the treatment plant; i.e., on the order of
under 10 pounds of BOD5/1000 pounds source wool (Ref. #141).
One analysis of raw wool contaminants is as follows:
Clean, dry wool - 62.5% (by weight)
Regain moisture - 10.OX
Suint & associated
moisture - 10.0%
Grease - 6.OX
Dirt - 11.5%
Suint is described as potassium salts of organic acids, and is derived
principally from urine and dried sweat.
Analyses vary widely depending on the source of the wool, and as
mentioned in chapter IV, the total non-wool materials may be 25 to 75
percent of the grease wool by weight.
Category 2 - Wool Finishing
As mentioned, the metallized dyes used for wool are very fast (i.e., do
not fade or rub off readily). Hence on 100 percent wool cloth, these
dyes are often used. In the blends, however, the dyes used for
polyester and other synthetic fibers have poorer fastness, so in these
blends many woolen mills have converted to non-chrome dyes. As a
•result, an all-wool mill may be expected to have significant chrome in
its effluent, but in a wool-blend mill, the chrome will be considerably
less or even nonexistent.
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Since the wool mills investigated appear to be working mostly on blends,
principally polyester, carriers such as orthophenol, phenol, diphenyl,
or benzoic acid derivatives will be present at significant levels in
their raw wastes. Phenolics appear to be losing favor because of their
odor, but current practice includes them and they will be present in
most woolblend mill wastes.
As a result of the above, the principal component that distinguishes the
wool mill Category 2 from Category 5, Knit Finishing, is the chromium
used to dye the wool. However, since we are recommending a generalized
guidelines on chrome, this difference is of no consequence.
The Category 2 mills (see Process description) have a higher water usage
rate than any other finishing category. The heaviest contributor
appears to be the rinsing after fulling. In addition, the wool and wool
blends are more expensive fabrics and their higher quality necessitates
more washing to reduce crocking, or rubbing off of color.
Category 3 - Greige Mills
Wastes at greige mills constitute residues in size boxes at the end of a
day or a week, and water used for clean-up. The volumes of textile
wastes in a greige mill are small. Significant amounts of water used in
a greige mill (e.g., cooling water) may not enter the waste treatment
plant.
The total waste load at a greige mill is typically greater than 90
percent sanitary and the remainder is industrial.
Treatability of greige mill wastes is related to the size used. Starch
is very readily degraded biologically, and may be given a preliminary
enzyme treatment to improve biodegradability. On the other hand, poly-
vinyl alcohol is consumed by organisms relatively slowly, though recent
studies show that organisms acclimate to polyvinyl alcohol. (See
Category 4 below.)
Category U - Woven Fabric Finishing
Wastes associated with finishing woven goods are indicated by the
technology summarized for this category in Chapter IV. The wastes
result from removal of foreign material during the cleaning and
bleaching of cotton (and its blends) and from the various chemicals used
in finishing the fabric. In the description which follows, individual
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DRAFT
processes are discussed in the same order as will be found in chapter
IV, Category 4.
Enzymatic removal of starch size generates starch solids, fat or wax,
enzyme, sodium chloride and wetting agent in the effluent stream. The
waste contains dissolved solids (both organic and inorganic), suspended
solids, and some fat or wax; it has a pH of 6 to 8, is light colored,
and contains no toxic materials.
Sulfuric acid removal of starch size generates waste containing starch
solids, fat or wax and sulfuric acid. It contains organic and inorganic
dissolved solids, suspended solids, and some oil and grease. It has a
pH of 1 to 2 and is relatively light colored.
Polyvinyl alcohol and carboxymethyl cellulose are both removable with
water alone, Desizing these materials will thus contribute suspended
solids, dissolved solids and oil and grease. Since these sizes are used
at about one-half the concentration of starch, the total solids
generated in the waste stream are about one-half the level corresponding
to starch use. When mixtures of starch and polyvinyl alcohol are used,
desizing may involve the use of enzyme (to solubilize the starch) and
water; total wastes generated would be intermediate between that deve-
loped by either size used alone.
Desizing may contribute 50 percent or more of the total waste solids in
a woven goods finishing mill.
The contribution of starch to BOD of waste streams has been documented
many times. On the other hand, polyvinyl alcohol has been considered
very slowly biodegradable, and as such, a major source of COD. Recent
studies performed by producers of polyvinyl alcohol in cooperation with
textile mills, indicate that biological waste systems will develop
organisms acclimated to polyvinyl alcohol, and when this has occured,
biodegradation is relatively rapid and complete.
Scouring
The major chemical used in scouring cotton, crustic soda, appears in the
waste stream. A surfactant and a small amount of sodium phosphate are
frequently used, and these also appear in the waste stream. The wastes
will also contain cotton waxes, which amount to 3 to 4 percent of the
cotton used.
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DRAFT
Scouring liquors are strongly alkaline (pH greater than 12) , and dark
colored due to cotton impurities. They contain significant levels of
dissolved solids and oil and grease. A modest level of suspended solids
results from the presence of cotton impurities.
The natural cotton impurities removed from greige fabric by scouring
contribute BOD and are biodegraded rapidly.
Scouring of cotton/polyester greige blends generates the same waste in
proportion to the amount of cotton.
Scouring of synthetic woven goods generates a low level of dissolved
solids from surfactant, soda ash, or sodium phosphate.
Mercerization
Mercerization wastes are predominantly the alkali used in the process.
The waste stream contains high dissolved solids, and may have a pH of 12
to 13. BOD level is low, and is due to penetrant used as an auxiliary
with the caustic. Small amounts of foreign material and wax may be re-
moved from the fiber, and will appear as suspended solids, and wax in
the wastes; these materials will contribute a small BOD load.
In large mills, caustic soda is recovered and concentrated for re-use,
thus saving chemical and avoiding a sizeable waste load. Estimates have
indicated that recovery of mercerizing caustic is justified when the
caustic use is more than 5 million pounds per year (dry) , and
concentration of the alkali is not permitted to fall below 2%.
Bleaching
Bleaching with hydrogen peroxide contributes very small waste loads,
most of which is dissolved solids. The dissolved solids are both in-
organic (sodium silicate, sodium hydroxide and sodium phosphate) and
organic (a surfactant and chelating agent). The waste stream contains a
low level of suspended solids when goods containing cotton are bleached.
Dyeing
Dyeing processes contribute substantially to textile wastes. Color is
an obvious waste. Examination of Table IV-4 shows that a high level of
dissolved solids is expected. Suspended solids should be low.
Carriers, which are essential for dyeing polyester and acetic acid, have
high BOD. Sodium hydrosulfite has a high immediate oxygen demand.
Plants using
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DRAFT
sulfur dyes will contain sulfides in the raw waste, and dichromates may
be a waste when vat dyeing is practiced.
Some of the wastes from dyeing textile fabrics are related to the pro-
duction equipment and to the size of the mill. The use of pressure
becks to replace atmospheric becks, and thereby decrease the amount of
carriers employed, has already been mentioned. On long runs, where
continuous Thermosol dyeing of synthetics or synthetic blends can be
justified, carriers may be avoided; a gum will be used, and will
contribute a low BOD.
Table IV-# also shows alternative chemicals that may be used as substi-
tutes for soium dichromate. Controls are available for the reduction of
vat dyes and their re-oxidation; use of the controls will minimize
wastes.
Printing
Printing wastes are comparable in many respects to dye wastes. As
stated in chapter IV, printing requires use of gums, which will
contribute BOD. Solvents (Varsol) and glycerine are also common
constituents in printing, but pose no special waste treating problem.
Printing pigments will introduce some suspended solids into the waste.
Much of the wastes from printing comes from cleaning of make-up tanks
and process equipment. These relatively concentrated wastes may justify
segregated treatment, perhaps by incineration.
Other Treatment Wastes
Wastes from resin treatment, water-proofing, flame-proofing and soil
release are small, since the chemicals are applied by padding, followed
by drying and curing. The chemicals used are diverse and small amounts
of them will enter the wastes.
Category 5 - Knit Fabric Finishing
The unit operations of knit fabric finishing are diagrammed in Figure
IV-6. The unit operations that produce liquid wastes have been
described in the preceding section. Category 4, Woven Fabric Finishing.
The main differences between knit and woven fabric wet processing
operations are that knit yarns are treated with lubricants rather than
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DRAFT
with the starch or polymeric sizes used for woven goods yarns, and that
mercerizing operations are not employed with knit goods. Otherwise, the
character of the wastes generated from comparable unit operations
performed on different fibers—cottons, synthetics, and blends—are
similar to those found in woven fabric finishing.
Lubricating finishes applied to knitting yarns generally are based on
mineral oils, vegetable oils, synthetic ester type oils, or waxes, and
may also contain antistatic agents, antioxidants, bacteriostats, and
corrosion inhibitors. Specific formulations are proprietary with the
yarn supplier or throwster who applies the finish. The amount applied
varies with the type of yarn; general levels of add-on by weight percent
on yarn are: untexturized synthetic yarns, 1 to 2 percent; texturized
synthetic yarns, 4 to 7 percent; and cotton yarns 3 percent or less.
These knitting oils are readily emulsified or soluble in water, and are
removed by washing prior to the dyeing operation.
Category 6 - Carpet Mills
The carpet industry wastes are very similar in nature to those from
Category 5, Knit Goods. When polyester is dyed, the carriers present
the same problems as in other categories, but very little polyester is
being used or will be used until a satisfactory answer to fireproofing
is found. Therefore, the nylon, acrylic and modacrylic dyeings pre-
dominate. This means very little phenolics from carriers, and very
little chrome from wool dyeing. Spin oils from the yarns are present.
A special waste, peculiar to this industry, exists because of the use of
foamed and unfoamed latex backing. The latex is not soluble in water
but is used in a highly dispersed form; hence suspended solids and COD
could be a problem unless they are coagulated. This stream (from
equipment washdown once a day to once a week) is usually segregated,
acidified to hasten coagulation, and settled before it joins dyehouse
wastes.
Municipal treating plants require pretreatment of the carpet mill wastes
to remove fiber and latex. Any latex that enters the sewer lines tends
to form strings and can cause appreciable deposits.
The pH of carpet wastes is usually close to neutral.
With the lack of other wet processing steps in the mill, the hot dye
wastes sometimes present a problem to biological treatment systems.
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The color problem is similar to that of other finishing categories.
Where carpets are printed, the thickeners present a high BOD load, as in
fabric printing.
Category 7 - Yarn Dyeing and Finishing
Wastes generated in yarn processing plants will depend substantially on
whether natural fibers, blends, or synthetics alone are processed.
when synthetics alone are handled, only light scouring and bleaching is
required, and wastes would be low levels of detergent, soda ash, sodium
phosphate, and perhaps a low bleach level. Wastes for this step would
have low BOD, and dissolved solids. Dyeing would contribute a stronger
waste, primarily due to carrier in the case of polyester, and to some
acetic acid; wastes, of course, would contain some color.
Scouring, bleaching, and mercerizing of cotton generate BOD and color
because of the fiber impurities, and a high level of dissolved solids
because of the mercerizing. Because of the relatively low amounts
involved, it does not appear reasonable to recover caustic soda.
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SECTION VI
SELECTION OF POLLUTANT PARAMETERS
Selected Parameters
Selection of pollutant parameters was based on the EPA study which
recommended effluent levels, tentative (Denver Guidelines); the American
Textile Manufacturers Institute study which followed publication of the
EPA document; on discussions with state water pollution control
officials, concerned industry personnel, and internal ADL consultants;
and on literature data. The following list of chemical, physical and
biological pollutants was developed:
BODS pH
COD color
Suspended Solids Alkalinity
Phenols Temperature
Oils and Grease Sulfides
Ammonia and Nitrate Nitrogen Chromium
Phosphates Other Heavy Metals
Dissolved solids Coliform Bacteria
Toxic Organic Chemicals
These pollutant parameters have been identified in the industry's
wastewaters; however, no category of the industry is known to have all
of these pollutants present in its wastewaters. Pollutants used in
cooling systems for algae and corrosion inhibition are not included in
the above list although these might be encompassed in several of the
parameters. It was assumed that effluent limitation guidelines deve-
loped for steam-electric power generation would be applicable to cooling
towers. Similarly, in the case of backwash water from water treatment
plants, it was assumed that guidelines developed for water treatment
would be applicable.
Specific Pollutants
BOD 5
The organic chemicals used in the industry uses are known to have a wide
range of biological oxygen demand, varying from completely biodegradable
compounds such as starch to highly refractory compounds such as dyes-
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Concentrations of BODS in the raw wastes may vary from about 50 mg/liter
to 3000 mg/liter. The values depend on the fibers processed, the
chemicals used, and on processing methods.
Oxygen demanding portion of the wastes are treatable biologically, with
only a few exceptions. The ease and degree of removal in a given time
are quite variable.
COD
The chemical oxygen demand test is one method for determining
carbonaceous substances; the COD concentration of wastewater streams
from an industry with a significant amount of organic wastes would be
expected to be high. Although the data base for evaluation is limited,
the variability of COD appears to be high. The removal of chemical
oxygen demand to the same efficiencies as BOD in a biological system is
not at present attained. The efficiency of COD removal is specific to
individual chemicals and processes and cannot be generalized for the
industry,
Suspended Solids
Suspended solids are present in textile wastewaters as a process waste
generated from the fibrous substrate, the chemicals used, and the
biological treatment. Most of the solids may be removed in clarifiers,
in settling basins, by filtration, or by other techniques.
Chromium
Selection of chromium as a pollutant parameter is based on its wide use
as an oxidant in the form of sodium dichromate for vat and sulfur dyes
and as a component of wool dyes. Substitutes are available, and several
mills are abandoning its use, but it is still widely used.
Other Heayy Metals
Copper salts are still used in some dyeing operations of the textile
industry. Since it is toxic in biological systems, it should be con-
sidered as a pollutant. Zinc nitrate is widely used as a catalyst for
durable press goods, and small amounts will enter waste systems.
Magnesium chloride may be used in the same process. Mercury was con
sidered because of its known occurrence in raw materials such as sodium
hydroxide which is used in large amounts by the textile industry. In
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normal operation, we would not expect the concentration of these
materials in the wastewater to exceed the toxic limits.
Phenols
Phenols are widely used as carriers in dyeing polyester and blends.
Some dye compositions (naphthols) will probably analyze as phenols also.
In addition, some natural materials, such as lignin residues removed in
scouring cotton, probably analyze as phenols,
gulfides
Since sodium sulfide is used in one type of dyeing, and other sulfur
containing chemicals are used, it was presumed that sulfides should be
considered among the parameters. Small amounts of sulfides may be
generated in processing wool.
BS
The variations in pH cannot be characterized across the industry since
some processes require highly acid conditions and others highly
alkaline. Neutralization is practiced where pH control is necessary to
prevent adverse effects in biological waste treatment systems.
Color
color is a major pollutant in the textile industry. Some color is water
soluble and some is not (dispersed dyes). Biodegradability is highly
variable. Many hues are used in dyeing, and all may appear in wastes;
their combination in waste streatms frequently generates a gray or black
color. As a pollutant parameter, color is an aesthetic rather than a
toxicity problem, and there is no universally accepted monitoring
method, although several techniques are being tried.
Alkalinity
Although many mills will continue to use alkalinity to follow treatment
plant operation, we do not believe this parameter is warranted as a
guideline.
Dissolved Solids
Dissolved solids, essentially inorganic salts, are an integral part of
several textile processes. (See Chapter IV.) Some organic salts, such
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as sodium acetate, are also present. Concentrations of dissolved solids
can vary from only slightly greater than the level in the incoming water
to perhaps as great as 5,000 ppm in wastewaters in certain segments of
the industry.
Phosphates
Phosphates are widely used, particularly in scouring processes, and may
also be added as nutrients to biological treatment systems. Phosphates
form part of the total dissolved solids, but their importance in
organism growth warrants special attention as a pollutant.
Grease
Grease is a substantial pollutant in wool scouring; in other textile
categories, it is much less troublesome but may still be significant.
Ammonia & Nitrate Nitrogen
Nitrogen from textile processes as well as from the aerobic digestion of
waste biological sludges may appear in wastewater as ammonia or nitrate
nitrogen because of the many chemical forms it may enter into (the
result of biological activity) . Additions of ammonia or urea as a
nutrient to nitrogen deficient waste is a common practice in the
industry.
Cgliform_Bacteria
Sanitary sewage is a component of many textile waste treatment plants,
and is often desired for its nutrient value. Consequently, coliform
bacteria may be present in large numbers in raw wastes and in treated
wastes. Some states require chlorination to destroy coliform bacteria.
Since fecal coliform organisms are not a true textile waste, we suggest
that the guideline should be the same as for sanitary systems with
secondary treatment (Federal Register, 38, 82, April 30, 1973).
Toxic Organic chemicals
Dieldrin, a moth proofing agent used for carpets would fall into this
grouping, but this chemical is no longer used. Some carriers,
particularly chlorinated benzenes, are toxic and should not be used.
Temperature
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Raw waste from many textile mills is hot, but temperature reduction
occurs naturally in waste treatment, and temperature of the final
effluent should be very close to ambient. Therefore, effluent water
temperature does not represent a problem.
Condensed Parameter List
Many but not all of the above pollutant parameters can be observed in
wastewaters from the different segments of the industry. The extent of
industry data was highly variable.
BOD, COD, suspended solids and pH levels are minimum requirements
applicable to the entire textile industry. COD is important but the
significance of the test and its limitations are not sufficiently
understood at present. Other parameters among the list given above
should be measured in the industry categories where they have been
identified in the waste effluent as indicated in Table VI-1.
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TABLE VI-1
Pollutant Parameters to be Measured in the Textile Industry
Industry Category
Parameter
BODS
COD
Total suspended solids
Chromium
Phenol
Oil & Grease
PH
Sulfides
Color
I
X
X
X
X
X
X
X
X
II
X
X
X
X
X
X
X
X
X
III
X
X
X
X
X
X
X
IY
X
X
X
X
X
X
X
X
V
X
X
X
X
X
X
X
X
VI
X
X
X
X
X
X
X
X
VI
X
X
X
X
X
X
X
X
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SECTION VII - CONTROL AND TREATMENT TECHNOLOGY
Wastewater Treatment Technology
The technology for control and treatment of waterborne pollutants in
the textile industry can be divided into two broad categories: in-process
and end-of-pipe. In-process control of waterborne pollutants in turn
depends upon two major conditions: (1) altering the process requirements
that generate water pollutants, and (2) controlling water usage in non-
process as well as process areas. For example, pollutants can often be
kept from entering water streams through the institution of better
housekeeping procedures, containment of leaks and spills, good mainten-
ance practices, and the segregation and treatment of selected concentrated
wastewater streams.
At present, the textile industry is concerned principally with end-of-
pipe treatment of its wastewaters. However, the application of wastewater
treatment technology has often been instituted without detailed investi-
gation of the alternatives to water and wastewater management within the
process operations. This approach, of course, is a natural one to follow
since institution of in-process changes for an operating plant is fre-
quently time consuming and expensive. Furthermore, the incorporation of
in-process control of waterborne pollutants demands attention to specific
operations which are often proprietary whereas end-of-pipe wastewater
treatment technology is based on generally similar principles which are
available from consultants, equipment manufacturers and the company's own
competitors.
The textile industry relies principally upon biological treatment of its
wastewaters at the end-of-pipe. A large number of plants, especially
small ones, send wastewaters into municipal sewage systems where they
may be a minor portion of the total flow; however, in some instances the
wastewater flow to a municipal plant is predominantly wastewater from
textile plants.
Evaluation of data obtained from the plants surveyed indicate that the operatic
biological systems is extended aeration, since no plant had an average
residence time in the aeration basin of less that 17 hours. The con-
sequent operating conditions are reflected in the relatively low levels
of BOD5 per 28.32 Cu m (1000 Cu ft) of aerated basin as well as the low
power inputs per kg (Ib) BOD removed. This results in low rates of
BODS removal per unit energy input to the aerators and relatively small
amounts of excess sludge because of the high degree of oxidation of the
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biologically active substances.
Where data on correlation of mixed liquid suspended solids were available,
these were found to be within the usual range for extended aeration. The
plants ranged in size from a 3.785 Cu m/d (1000 gpd) pilot plant to a
43,906 Cu m/d (11.6 mgd) plant. Although there is little necessity for
equalization basins to ameliorate the effects of flow variability, some
operational problems are unique to the textile industry as discussed in
the following paragraphs.
Removal of fibers from the wastewater prior to their entering the aeration
basin is often necessary to prevent floating scum from building on the
surface of the basin or to prevent the aeration equipment from malfunctioning
and reducing oxidation efficiency. Usually, these fibers are removed
satisfactorily through the use of bars or screens.
The wool scouring portion of the textile industry must cope with the most
severe wastewater treatment problems within the textile industry. This
results from the high concentration of greases, salts, and other substances
that are removed from the wool during scouring. The wool scouring wastes
must be pretreated prior to putting them through the biological system. The
high concentration of greases that are strongly resistant to biological
degradation
requires physical-chemical treatment ahead of the
biological system. The greases are usually emulsified during the scouring
with soap and detergents and consequently, present a severe removal pro-
blem.
Many treatment methods have been proposed and investigated at laboratory
levels. Those which are used most frequently are based on the use of
acids (to help break the emulsion) or centrifuges. Heating, filtration,
sedimentation, etc., are employed to separate the greases; however, the
reduction of greases to very low levels was not observed in any plants.
Furthermore, discussions with industry personnel indicated that a broad
spectrum of removal methods had been tried, but with no outstanding
commercial success.
Suspended solids are removed from biologically-treated wastewater by
gravity sedimentation. The concentrated slurries are recycled to
aeration basins while the overflow from the clarifier goes to lagoons
for further polishing or discharge to the receiving stream. Because
of colloidal particulates from certain operations, chemical coagulation
is required prior to biological treatment. This operation is usually
carried out by the addition of coagulating chemicals and/or the use of
coagulant aids to improve gravity sedimentation. In general* the
clarifiers used in the textile industry are designed for overflow rates
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considerably less than those usually found in biological treatment
systems today. .The average for 16 wastewater treatment plants was
15.a Cu m/sq. m-d (378 gpd/sq. ft.) which is approximately 60 percent
of the design values usually found acceptable. Excluding one extremely
high value of suspended solids concentration, the average concentration
of suspended solids from 25 plants was 57 mg/1. This concentration in
conjunction with the aforementioned low clarifier overflow rates, indicates
that the removal of suspended solids by gravity sedimentation is difficult.
The principal parameter for measuring the performance of the textile
industry's wastewater treatment plants is the reduction in biological
oxygen demand across the system as measured by the BODS test (7.1, 7.2).
Excluding the high BODS values for wool scouring—
category 1, the average BODS concentration of the remaining plants was
21 mg/1, running from a low of 2 to a high of 83. Of this group only
approximately 20 percent exceeded a 30 mg/1 standard being recommended
for municipal sewage treatment plants (7.3).
These data show that exemplary wastewater treatment plants for six of the
seven categories are being operated to give values of BODS in the treated
effluent comparable to or better than those generally accepted for treat-
ment of municipal sewage. Of course, this performance is being achieved
under operating conditions that differ from those for sewage. In effect,
many of the wastewater treatment plants are being operated as a two-stage
biological system since polishing lagoons of various residence times
follow the aerated basin.
The long residence time in the aeration basins and polishing lagoons of
the plants surveyed implies that land availability was of no great
concern.
Chemical oxygen demand (COD) is measured less frequently than BODS since
the later is the parameter of major concern to present regulatory agencies.
As in the case of BODS, the COD of wool scouring waste is greater than
that of wastewaters from other categories, both on a concentration basis
and as units/unit of production. Exclusive of the wool scouring waste,
the industry's average COD for the plants surveyed is 222 mg/1 with a low
value of 68 mg/1 and a high of U27 mg/1. The ratio of COD to BODS
increases significantly across the wastewater treatment plants,
which indicates the refractory nature of some of the
components of the wastewaters. Although COD is probably a better measure
of the pollutant level of wastewaters, other parameters such as total
organic carbon (TOC) or total oxygen demand (TOD) might be even more
indicative (7.1-7.7). No data on the latter two were obtained.
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Although the ratio of COD
to BOD is generally recognized as an indicator of the biologically
refractory nature of wastewater pollutants, the variability in this
ratio is affected by many factors, and one of the most important is the
capabilities of a specific biological system to degrade carbonaceous
substances. For example, PVA, one of the biggest sizes used in the
textile industry, is considered to be essentially refractory in terms
of its loading on an activated sludge plant, 1 percent BOD, whereas the
theoretical oxygen demand is 36 percent. This would indicate that only
3 percent of the PVA is normally attacked in a five-day BOD test, or
loosely speaking, 97 percent of it would pass unaffected through an
activated sludge plant (7.8) . Recent data shows that this is not the
case; in some activated sludge plants where the organisms have become
acclimated to the PVA, substantial PVA reduction is achieved. For
example, Blair Mills, Belton, South Carolina, consistently shows over
90 percent reduction of PVA in its extended aeration (5 days) activated
sludge plant (7.9).
Other waste treatment plants report varying amounts of PVA removal and
some unpublished laboratory work indicates that up to 20 days residence
time in an activated sludge is required for effective removal. Obviously,
one of the big differences between waste treatment plants, with respect
to effective removal of PVA is the different types and relative propor-
tions of each microorganism that eventually evolve in the individual
activated sludge plants, because of the different types of raw waste
loads.
From the above discussion, it can be seen that the biological refractivity
of certain carbonaceous substances may be uniquely a function of the
biological system acclimated to a specific wastewater composition. Never-
theless, an indication of the COD concentration that might remain in a
biologically-treated wastewater can be obtained by assuming that the COD
test is composed of the sum of two components: (1) the biologically
degradable carbonaceous substances in the wastewaters, and (2) the non-
biodegradables. This is tantamount to the following equation:
CODmeasure = CODnon-degradable + b(BOD5)
where b is the conversion factor for BODS to COD. From this relationship
where both influent and effluent analyses for COD and BODS were available,
the values of COD non-degradable and b were calculated as well as the
estimated COD at 15 and 30 mg/1 of BODS (Table VII-1) .
This approach indicates that if all of the BODS contributors were removed
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from the wastewaters only three of the plants would achieve COD concen-
tration levels less than 100 mg/1. Whether this would indeed occur in a
biologically active system with sufficient residence times to lower the
BOD concentration to near zero is problematical since only truly non-
biodegradable substances would report as CODND. Nevertheless, this
approach is believed to indicate the carbonaceous substances that might
be expected in the effluents from wastewater treatment facilities operating
with the best practicable technology currently available.
The wastewaters from the textile industry usually contain ample phosphates
which are available as nutrients for the microorganisms of the biological
system. Indeed, there is more apt to be an excess of phosphates, due to
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Table VII-1
CalculatedValues of COD Non-degradable
COD at COD at
Category Plant Slope b CODND (mg/1) 15 mg BOD5/1 30 mg BOD5/1
I A
B
II C
D
E
IV M
L
0
S
V W
Y
VI BB
CC
VII GG
3.41
4.26
2.13
1.87
4.87
1.62
1.48
2.56
3.27
2.85
1.75
4.59
0.75
0.96
1,700
'137
82
142
19
174
182
172
70
270
398
203
439
60
1,750
500
113
169
92
198
203
210
119
312
424
271
450
74
1,800
565
145
197
165
222
226
247
168
355
450
341
461
88
the high usage of detergents, and a deficiency of the nitrogen necessary
for maintaining a viable biomass in the system, consequently, nitrogen,
in the form of nitrates or ammonia, usually must be added to the waste-
waters to maintain high removal efficiencies in the treatment plant.
Textile process operations often require high-temperature water,
however, heat reclamation is also widely practiced as a matter of
economics so the wastewaters sent to the treatment plants usually do not
present any significant thermal shock problems. Furthermore, the long
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residence time generally found in the wastewater treatment systems
serves effectively to prevent rapid changes in temperature. The most
important temperature effect is not expected to be high temperatures,
but low temperatures. In northern areas, the low wintertime
temperatures in biological treatment systems will materially reduce the
biological activity and thus the efficiency of BODS removal.
Color in the wastewaters of the textile industry is inherent in the
nature of the operations. Since color chemicals are specifically
formulated for resistance to degradation under the oxidizing conditions
of the world, it is not surprising that removal of color in aerobic
biological systems is erratic. Although color concentration normally is
reduced somewhat in the biological systems surveyed, data obtained were
in arbitrary units, most often APHA(Y) standard. Color removal
efficiency is known to be highly specific to the individual plant and
the particular processes being operated at a given time. Although a
number of research and development projects have been carried out, there
is no one generally accepted method for color removal. Use of
adsorptive technology—such as flocculation and activated carbons—and
anaerobic treatment appear to offer the best possiblity for removing
color; as noted earlier, however, the effective application depends upon
specific knowledge about individual wastewater streams. Chemical
oxidation by chlorine, ozone, etc., has been tried, as well as ion
exchange, electrodialysis, ultrafiltration, and reverse osmosis. These
treatment techniques are discussed in detail in Section VII-6.
Chromium is the most significant heavy metal of concern in the textile
industry although others are employed selectively. There is good
evidence that at low levels of chromium in the raw waste (less than 15
ppm) an activated sludge treatment plant removes a substantial portion.
Reference 7.12 states that 50 ppm of Cr+6 fed continuously lowers the
BOD removal efficiency of a waste treatment plant by only 3 percent.
Pollution experts within the textile industry have noted that chrome
removal across a waste treatment plant is proportional to the amount of
BOD removed (more specifically the excess sludge removed) and is
inversely proportional to the amount of suspended solids carried over in
the final effluent from the secondary clarifier.
The removal of chromium ions by chemical treatment methods is well known
although it was not found in the textile plants surveyed. It is
apparent that such systems will have to be applied at plants using
chromium. One of the simplest chemical system involves reducing the
Cr+6 using SO2, and precipitating the resulting Cr+3 with NaOH, which is
sent to a settling lagoon. Good practice is to carry out the chemical
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precipitation of the chrome on the segregated streams that have chrome,
and feed the effluent from this system to the activated sludge plant for
treatment for BOD.
Wastewaters from ancillary operations such as cooling towers, steam
generating facilities and water treatment plants may be significant
factors in the wastewater volumes emitted from the textile industry. In
those instances where one must handle cooling tower and boiler blowdowns
that contain corrosion inhibiting chemicals, algacide and biocides, the
technology for selective removal is usually available. Of course, the
best practicable control technology currently available for process
wastewaters will not remove soluble inorganic salts which predominate in
these blowdowns. Toxic and hazardous substances in these systems can be
controlled either by eliminating them, replacing them with less toxic
and hazardous substances or treating isolated streams to remove them.
Selection of a course of action to cope with toxic and hazardous
materials in these blowdowns is more a question of economics than a
question of technology.
Reliability, operability and consistency of operation of the wastewater
treatment processes found to be most frequently used in the textile
industry can be high if appropriate designs and operational techniques
are employed. The end-of-pipe treatment utilizing extended aeration
biological systems is a well established technology that requires
attention to a limited number of variables to insure a high degree of
reliability. Although many variables can affect the operability of a
biological system, in general the best overall performance is achieved
when the highest consistency of flow and wastewater composition occurs.
Since the textile industry is predominantly a batch type process
operation rather than continuous, such as the petroleum or petrochemical
industry, it follows that both flow rates and wastewater composition
will vary significantly. That the industry recognizes this variability
is apparent from the nature of the wastewater treatment systems, i.e.,
long residence time systems which hold sufficient volumes so that high
instantaneous flow rates or high concentrations can be rapidly equalized
to prevent "sharp loading" of the biological system. Removal of
greases, oils and fibers, and in certain instances control of pH, prior
to aeration preconditions the wastewaters for most effective operation
of the biological system.
The most important operational aspects of these extended aeration
systems are equipment reliability and attention to operating detail and
maintenance. Spare aeration equipment (usually floating surface
aerators) improves the possiblity of consistent operation; however, many
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treatment systems have an adequate overcapacity already installed as
insurance against the results of equipment failure. In general,
auxiliary power for operation of the wastewater treatment system would
not be required unless the plant was equipped with a source of auxiliary
power and could, therefore, keep operating despite failure of the
primary power source. Operability and consistency of performance could
be improved if parallel treatment systems existed, each of which was
capable of handling the total load. However, this is rarely justifiable
on either an economic or practical basis; it is more desirable to
install spare equipment at critical points, for example, sludge return
pumps. Perhaps of equal importance is a design that permits rapid and
easy maintenance of malfunctioning equipment.
Therefore, control of the biological treatment plant and the consistency
of the results obtained are largely a matter of conscientious adherence
to well-known operational and maintenance procedures. Automatic control
of biological treatment plants is far from a practical point. Although
in-line instrumentation for measurement of pH, dissolved oxygen,
temperature, turbidity and so on, can improve the effectiveness of
operation, its use is minimal in the textile industry's existing
wastewater treatment plants. Nevertheless, no practical in-line
instrumentation can replace the judicious attention to operational
details of a conscientious crew of operators.
In Process Control
Ancillary Process Control Technology. A big portion of the textile
waste loads is inherent in the methods of textile processing and
independent of the efficiency of the processing plants. For example,
size is applied to warp yarns to give them mechanical strength in the
weaving operations; all of this size must be taken off before subsequent
bleaching and dyeing. A finishing plant can use variable amounts of
water in removing this size, but the raw waste load due to size is
unchanged. The same applies to spinning finishes on synthetic fibers,
which are put on the yarn as a lubricant and to reduce static in the
high-speed spinning and textile operations. All of these "temporary"
finishes must be removed before dyeing of the yarn, so again the raw
waste load is almost independent of scouring efficiency.
Although these "base" raw waste loads are constant, a plant can reduce
the other raw waste loads—such as spills, reworks, etc.—in many ways.
These are considered below.
The principal axiom in reducing the waterborne pollutant loads through
control external to the process is to prevent pollutants from entering
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the water streams. Although this seems obvious, its successful applica-
tion requires continual attention by operating personnel. In fact, it
is synonomous with creation of an effective work safety program. In the
textile industry, with its large number of batch operations, one of the
most important aspects of reducing waterborne pollutants is to institute
an effective water management program—including expanded use of liquid-
level-controls, flow indicators and flow meters, adequate capacity for
generating hot water for wash operations, etc.—in conjunction with a
good maintenance program which will insure that leaks from valves,
pipes, pumps, etc., are promptly repaired so as to prevent process
fluids from entering floor drains, etc. Except for category 1 the
concentration levels of pollutants at the inlet to the wastewater
treatment plants are not excessively high for industrial wastewaters (an
average BODS of 347 for 25 plants). Consequently, a significant
reduction in hydraulic capacity should normally effectively lower the
total emitted pollutants from a given wastewater treatment plant even if
the concentration level in the effluent rose moderately. Obviously, if
process operations can be changed to reduce the pollutant load to the
waste water treatment plant simultaneously with a reduction in hydraulic
flow the emitted pollutants will be reduced even more.
The textile industry is not a large volume handler of liquid chemicals
that would be water pollutants if storage tanks failed catastrophically
or if spills or leaks occurred during loading and unloading operations.
Consequently, the need for curbing and diking to prevent entry of
spilled or leaked liquids into waterstreams is not as great as in other
industries. However, where significant quantities of liquid chemicals
are stored and handled, provisions should be made for containment in the
case of accidents. Alternatively, provisions could be made for draining
to catch basins or, if appropriate, to the wastewater treatment plant.
Procedures and methods for preventing spills and leaks should be the
pramount consideration, but passive systems for containment or pre-
venting their entry into water courses should be part of any control
plan. Only through assessment of the potential for pollutants to enter
water streams from accidential occurences and the development of action
plans is it possible to develop a high degree of assurance that spilled
liquids will be prevented from polluting water courses.
In summary, strict attention to housekeeping procedures and process
operation, can minimize abnormal waste loads.
Conventional Processing With Better Water Economy The greatest potential
for improved water economy in the textile industry stems from the use of
better washing methods. About 80 percent of all the water used in
textile wet processing is used for removing foreign material—either
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that carried on the raw fiber, or materials resulting from treating
operations such as sizing, scouring, dyeing and finishing. Furthermore,
most applications of treating materials are already carried out at low
liquor ratio for the sake of material and time economy. It follows that
important water economies in conventional processing can be made only by
reducing the amount of wash water.
It is clear that in some segments the opportunities for water economies
in washing should be considerable. For example, a typical cotton
bleaching sequence calls for washing the fabric six times (following
desize, scour, bleach, mercerize, dye and finish steps). Although
washing requirements differ from step to step, we shall assume that at
each of these steps the fabric must be washed 99 percent free from the
last treating solution. At one extreme, simple dilution would require
45. 4 kg (100 pounds) of water for each .454 kg (pound) of contaminant to
be removed or 272 kg (600 pounds) of water per .454 kg (pound) of fabric
through the 6-step process. This amounts to some 265 1 (70 gallons) of
water per .454 kg (pound) of fabric. On the other hand, a 20-stage
extraction could reduce contaminants by 99 percent by the use of only
about .91 kg (2 pounds) of water per state of 5.4 kg (12 pounds), say
5.7 1 (1.5 gallons), per .454 kg (pound) of fabric through six stages.
It is to be emphasized that no washing machine in actual use or
conceptualized in mechanical design at this time can approach 20-stage
performance. Existing methods frequently use about 9.1 kg (20 pounds)
of water or more per stage, or about 54.5 kg (120 pounds) , 57 1 (15
gallons), per .454 kg (pound) of fabric through six stages.
It is relatively easy to conceive of fabric washing devices that achieve
some of the theoretical water savings. The problem is to make machines
that are reasonable in cost; not damaging to the relatively fragile
fabric surface; easy to thread up, capable of accommodating a range of
fabric widths, weights and types; and durable enough for continuous high
speed operation. In the past generation a good deal of progress was
made in washer design. The Tensitrol machine and the Williams-type high
turbulence open-width machine are examples. Driving force for these
improvements in performance was, in general, need for improved washing
effectiveness per machine (with resulting saving in floor space and
capital expense) and need for machines which minimized adverse effects
on the fabric, especially effects due to excessive tension and abrasion.
Water economy was not a high priority in the design, since textile mills
were usually located near abundant water supplies.
Water usage can be improved substantially as design engineers take water
economy into more active consideration. For example, so-called "double
laced11 box washers have recently been introduced, with claimed savings
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of up to 40 percent in number of machines (7.14). Significant water
savings are claimed, but detailed quantitative data are not available.
More complex open-width washing machines designed to induce greater
turbulence, have been offered without great success. Since the physical
aim to be accomplished is clear, i.e., breaking down an effective thick
diffusion film in the fabric interstices, it is likely that more
efficient open-width machines can be developed. The problem is to
provide suitable incentives for the development, testing and use of such
machines.
Rope washers generally are more effective than open-width washers, but
may be suspectible to further improvement if back-mixing can be
controlled in a practical manner.
In addition to better washer design, there are opportunities for water
economy in more counter-current flow. A finishing plant operator
prefers to use fresh water at every machine, for ease of control and
adjustment, and for freedom from danger of cross-contamination.
However, some opportunities for counter-flow are neither unduly
difficult nor hazardous to quality. For example, it is almost always
acceptable (but not always practiced) to counter-flow water from machine
to machine where several machines are used in series at the same point
in the process. For example, it is common to use 5 or 6 or more open-
width box washers in series after scouring or mercerizing operations, or
two Tensitrol-type rope washers after scouring operations. It is best
for water economy to counter-flow the water through the series. This is
frequently but not universally practiced today. Furthermore, it is
almost certainly practical to counter-flow water from some later stages
to some earlier stages. For example, white washer effluent can almost
certainly be used as feed water for caustic washers. Additional
opportunities for backflow of water also exist. However, there are
limitations; wash water from dyeing operations, for example, always
contains color, and is generally unsuitable for re-use without cleanup.
Caustic scour and desizing walsh waters are heavily laden with dissolved
and suspended solids and unsuitable for re-use.
In principle, water cleanup could be used around particular machines or
groups of machines, thus extending water economy still further. Pre-
liminary consideration of investment and operating costs indicates that
this is generally less conomical than pooling effluents and operations
of one large treating plant. Closing of water cycles around individual
operations or groups of operations will probably be limited to very
special circumstances.
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In summary, it is reasonable to suppose that further water economies can
be achieved by machine improvements and by wider use of counter-flow.
New Process Technology
Solvent Processing
Serious study of textile processing in organic solvents dates back at
least 15 years, although batch applications of special finishing, such
as water repellants has been practiced for more than a generation. In
the late 1950's, Imperial Chemical Industries pioneered a solvent system
for continuous scouring of cotton piece goods. Several large machines
of this type have been operated in the United States at various times
since 1960. During the 1960»s, a number of continuous solvent scouring
and finishing ranges were devised and tested in Europe. In most of
these cases the development work has been carried out by solvent
suppliers or equipment manufacturers.
In the course of this work it has become clear that chlorinated solvents
such as perchloroethylene and trichloroethylene are the most
advantageous materials now available. It has also become clear that
suitable machines can be manufactured and operated so as to control air
pollutions in the work space. Solvent loss remains an economic problem.
Extremely tight control is needed to keep solvent loss per operation
below 5 percent of fabric weight. To date, there has been no
appreciable commercial use of solvent finishing for woven goods.
However, solvent processing has established a firm if specialized
position in knit fabric finishing, especially in the finishing of
synthetic knits.
Solvent processing has found commercial use only where superior fabric
properties have been achieved. For example, solvent applications of
stain repellent finish to upholstery and drapery materials are widely
practiced. In this case, aqueous treatment is not always possible,
because the fabric is sensitive to water. Similarly, solvent scouring
and finishing of synthetic knit fabrics is widely practiced because it
is, in these cases, advantageous to quality to avoid wetting with water.
Some finishes, furthermore, are not available in water soluble or dis-
persible form and can be used only in solvents.
On the other hand, very substantial research and development efforts in
the last decade or so have not led to replacement of aqueous processing
to any appreciable extent. Some of the important problems are
summarized below.
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It is obviously an immense task to introduce solvent processing (or any
other completely new processing means) throughout a whole, complex
textile scouring, bleaching and finishing process. Aside from invest-
ment considerations, whole families of solvent-compatible reagents*
dyes, and finishing materials are needed. At present, these are
generally not available.
Given the above situation, it is natural to consider piecemeal
introduction of solvent processing, starting with the most advantageous
or easiest uses. Because the useful solvents are expensive, about
$1500.00 per 3.785 cu m (thousand gallons), and toxic, they must be
carefully contained during processing, and recovered as completely as
possible. Also, residues from scouring operations or from spent
reagents must be removed from the solvent (usually by distillation)
collected, and dealt with. These solid or semi-solid residues can be
difficult. For example, they usually contain some chlorinated solvent
residue which complicates disposal by either incinerator or land fill
routes.
Adoption of a complete solvent processing scheme avoids the problem of
dealing with both aqueous and solvent wastes. As noted above, however,
a complete line of textile processing and finishing compounds would
first be required. Some thousands of different dyestuffs and chemicals
are now used in commercial textile processing. Only a limited number
can be directly transferred to solvent use.
On the grounds noted above, it is becoming clear that solvent processing
generally will be introduced only as superior results are demonstrated.
In general, this implies better properties in the finished fabric,
although processing advantages may lead the way in a few cases. The
prospects for solvent processing are outlined below for each of several
important finishing steps.
SolventDesizing. Solvent sizing and desizing are discussed in a later
section.
Solvent Scouring
Woven Fabric. Despite intense effort (7.15, 7.16) solvent scouring of
woven fabrics has not established a firm place. The properties of
solvent scoured fabrics are not generally superior. The wastes
generated are the same with respect to organic content, but, of course,
free from the alkali generally used for aqueous scouring.
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Knit Fabric. Solvent scouring of some synthetic knit fabrics is well
established and growing. Commercial use is based on superior results,
fast drying (compared with water) and easy extension to specialized sol-
vent finishing. Contribution to water pollution abatement is modest
because scouring of knits does not contribute very heavily to textile
pollution loads.
Bleaching. It is possible to bleach from solvent syterns and large scale
demonstrations have been carried out (7.15). However, the process used
generates both aqueous and solvent wastes. No advantages have been
demonstrated with respect to fabric properties.
Dyeing. A very large effort has been devoted to solvent dyeing. Some
fibers are commercially dyed from solvent systems, notably nylon sports-
wear and carpets by the STX beam dyeing process (7.16). The advantages
and limittations of solvent dyeing, both practical and theoretical, were
discussed at length in a January 1973 AATCC Symposium. Collected
papers, available from the American Association of Textile Chemists and
Colorists Research Triangle Park, North Carolina, 27709, should be
consulted for details. Although many important textile fibers can be
dyed from solvent systems, practical applications will apparently be
limited to special cases.
There are not grounds for broad reliance on solvent processing to solve
current liquid effluent problems arising from dyeing operations.
Finishing
WovenGoods. It has been shown that many functional finishes can be
applied from solvents (7.17, 7.18). Some advantageous properties have
been demonstrated, but no practical use has been achieved. It is
believed that advantages shown so far have been insufficient to justify
a changeover from the familiar aqueous systems. In any event, chemical
finishing is but a modest contributor to textile effluents, since the
aim is to capture a very high fraction of the active agent on the cloth.
In special cases, i.e., water-sensitive fabrics, solvent finishing has
become fairly standard practice. Application of stain and soil resist
finishes to upholstery fabrics is a typical example.
Knit Fabric Finishing. Synthetic knit fabrics lend themselves admirably
to combination scouring and finishing from solvents. Some modern
finishes such as silicone polymers for single-knits, can be applied only
from solvent. Iri other cases, solvent processing recommends itself
because of ease and speed of drying, or because of superior properties
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developed by solvent finishing. Although much of this development
started with batch operations in dry cleaning machinery, high developed
continuous processing machines are now available from several
manufacturers, both domestic and foreign. It is clear that solvent
processing of knit fabrics is established and growing.
In summary, solvent processing is clearly finding a place in modern
textile processing. There are, however, no grounds for supposing that
aqueous processing will be totally displaced by solvent processing.
Recovery and Re-use of Warp size
Most woven goods require the use of warp size during manufacture. The
sizing, traditionally starch, coats the warp yarns and binds the indi-
vidual fibers together. This action is necessary to preserve the warps
from excessive abrasion damage during weaving. The sizing is generally
removed as the first operation in the fabric finishing sequence. Warp
size constitutes, on the average, about 5 percent of the weight of the
fabric, and it all ends up in the effluent waters. Accordingly, it is a
very substantial contributor to the total BOD and COD in textile mill
effluents. Sizing waste accounts for about half the total BOD and COD
load from textile operations.
Since the advent of synthetic fibers, newer sizing agents have been
developed. A solubilized cellulose derivative, and polyvinyl alcohol
have been widely used. At this time, PVA, alone or in blends with
starch, is the most popular size for the important cotton/polyester
blend fabrics.
Adaption of PVA has led to complications in regard to effluent
standards. PVA reports very low values in the conventional BODS test.
However, it has a higher COD than the starch it replaces. Recent work
indicates (7.19) that, despite the BODS test results, PVA is degraded
extensively in biological treatment plants. Both its alleged
treatability and its alleged resistance to attack have been cited as
advantages. These questions will presumably be resolved in the near
future.
Solvent methods offer one possible route to allocation of the heavy
pollution load from warp sizes. The concept is to apply a solvent-
soluble polymer, then remove it by solvent washing following weaving
and, finally, to recover the polymer for re-use. There is every reason
to suppose that suitable polymers can be found. At least two companies
(ICI and Dow Chemical) are actively working in this direction (7.20) .
Early indications are that solvent-applied warp size can be effective.
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The future potential of the process depends upon successful recovery and
re-use of the size. The most important problem to be expected is in
clean-up of the recovered size for re-use. As a practical matter» most
woven goods contain natural fiber (principally wool or cotton) and these
fibers contain solvent-extractable material.
Since the size is to be used repeatedly, some means to purge impurities
is mandatory. While this is a difficult problem, the potential advan-
tages of solvent size and desize are substantial. We believe that
solvent size/desize will eventually find practical application. It is
unlikely that such use will be based primarily on pollution control,
since, as noted above, conventional sizing agents are more or less
readily amenable to conventional biological treatment. EPA regulations
will, in all probability, lead to universal adoption of secondary treat-
ment of textile wastes and hence more or less complete solution of the
size waste problem before solvent size-desize is ready for large-scale
use. Consequently, it is likely that adoption of new sizing technology
will be based on demonstrated advantages over conventional methods
rather than on pollution control considerations alone.
Specifi c^Prgce s s^Categori es
Category 1-Wool Scouring. One of the problems in defining wool scour
wastes and in controlling the process for optimum performance is that
detergent is added on a fixed flow basis, and the' demand for it varies
widely with the natural variations in the fleece as received. Future
effort may profitably be spent in developing a method to measure the
detergent demand and control its addition accordingly; less detergent
will be used, BOD load reduced and perhaps a more easily separated
emulsion will yield higher grease recoveries.
In addition, in the centrifuge recovery system described, rewashing of
the grit for recovery of up to *»0 percent more grease than is presently
being recovered, appears possible with developmental efforts.
Furthermore, the value of centrifuge-recovered wool grease is higher
than that of acid-cracked grease (20* per pound in 1973).
Anaerobic treatment of wool grease as a substitute degreasing process
has been investigated and found to be promising. However, 68 percent
digestion was noted. The apparent success of aerobic methods operating
at over 90 percent digestion indicates that further anaerobic develop-
ment is probably not worth pursuing.
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Re-use of the waste treatment plant effluent as make-up water to the
scouring train may be feasible. One of the obvious problems is that
dissolved salts will build up.
With the resulting more concentrated solutions, incineration and recon-
densing the water may be economically reasonable. The grease problem
precludes present forms of reverse osmosis and other separation
techniques.
Solvent scouring has been used to remove the wool grease from the wool.
Jet fuel, benzene, carbon tetrachloride, ethyl alcohol, methyl alcohol
and isopropyl alcohol have been tried. The problems of flammability and
explosive hazards, and of efficiency of solvent recovery have prevented
its use in the United States.
Solvent scouring requires subsequent detergent washing to remove the
dirt. More efficient methods of grease recovery using the water
scouring process appear capable of achieving grease recovery levels
comparable to that with solvent methods, and hence would probably offer
the better choice for further reducing pollution load in the future.
Category, 2 _ - Wool Finishing. Further effort should be extended to
segregating waste streams within the mill. In particular, many of the
rinse waters appear satisfactory for reuse both for subsequent initial
rinses and for pre-scouring steps and perhaps for fulling rinses. These
approaches require careful evaluation because of the tendency for wool
fiber to "sour" if soaps and other materials are left on them for many
hours. Substantial investments in repiping and in storage facilities
are needed to accomplish this water reuse.
Solvent scouring is practiced in several mills in place of initial
detergent scouring, to remove spin oils, sizes, and fugitive tints. The
savings in detergent costs appear to justify these systems resulting in
a lower BOD load and somewhat lower water use.
.^ - Greige Mills . Aqueous wastes generated in sizing yarns
amount now to machine clean-up and incidental wastes. In one exemplary
plant, aqueous wastes were less than 0.8 I/kg (0.1 gal/lb) greige cloth
produced. Reduction of wastes at these mills is therefore
insignificant.
Category _ ft ^ Woven Fabric Finishing. The possibilities for reducing
water consumption in finishing woven fabric were discussed earlier. In
this section we will emphasize pollutants other than water.
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Scouring, mercerizing and bleaching generate substantial wastes, parti-
cularly in textiles containing cotton. Large textile users already
recover spent caustic soda and this should be extended to other users.
Better control and automation of dyeing processes could bring about
reductions in dye and chemical usage as well as in water.
There is no simple way to reduce the amounts of auxiliary chemicals
essential for dyeing, e.g., salts, sodium hydrosulfite and a few others.
Some mills are abandoning the use of chromates, and substitutes are
generally as effective. The use of pressure becks for dying polyester
is increasing, and reducing carrier usage significantly. Printing pro-
cesses frequently use solvents (Varsol) which can be recovered by flo-
tation and distillation.
Category 5 - Knits. The general comments concerning dyeing and
finishing made under category U apply.
Category 6 - Carpets. Continuous dyeing has been stated to use 20 to 25
percent of the amount of water used in beck dyeing. Stock dyeing and
printing rinse also are similar lower level uses. However, a mill can
use a continuous process only if the volume of a given shade is suffi-
ciently high.
If polyester regains as a major face-yarn material, there will be a
major increase in raw waste per kg (pound), which can be abated to some
extent by the use of pressure dye becks, as in categories 4 and 5, that
permit a reduction in the use of carriers and their attendant heavy BOD
load.
Complete recycling of water, since water use is centered on dyeing and
rinsing in this industry, depends on the same technology developments
for removal of dyes and salts that all other finishing categories depend
upon.
Category 7 -Stock and Yarn Dyeing and Finishing. Mills in this
category scour, mercerize, bleach and dye cotton, or scour and dye
synthetic fibers. Possible future developments that might apply to
these mills are discussed in this section under category 4.
ADVANCED WASTE TREATMENT TECHNOLOGY
In all categories of textile plants, we assume good secondary treatment,
i.e., that activated sludge will be combined with preliminary and possi-
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DRAFT
bly post screening and filtration. The definition of advanced treatment
systems is therefore confined to tertiary treatment of the secondary ef-
fluents, dewatering and incineration of sludges, and possibly to pre-
conditioning of some specialized waste streams to render them compatible
with the activated sludge process.
The polluting species that such advanced waste treatment systems must
contend with are typified by those commonly experienced in the effluents
of category 4 textile plants using modern secondary treatment:
flow a,000 - 30,000 cu m/day (1-8 mgd)
BODS 4-30 mg/1
COD 500 mg/1
TSS 300 mg/1
Cr 0-4 mg/1
Phenol 500 mg/1
color moderate
pH 7-11
alkalinity 800-1300 mg/1 (CaCO3)
phosphorous 2-4 mg/1
Source: A. D. Little, Inc., data
The chemical species which make up the BOD, COD, and suspended solids
fractions are not well characterized; even less quantified are such
other unacceptable characteristics of the effluent as color, foam,
nutrients, salts, bioactive agents, and other refractory organics.
In some cases, advanced treatment systems have been tried out on textile
wastes and their effectiveness in dealing with these various pollutant
parameters has been assessed. In other cases it is necessary to predict
their usefulness to the textile industry from experience with other
similar waste streams or by an understanding of the physico-chemical
principles involved. In most cases, pilot plant work must be done be-
fore the effectiveness or cost of advanced treatment processes can be
predicted with any confidence for a specific waste stream.
In the past, many advanced processes have been rejected for use in the
textile and other industries after some experimentation. However, as
pressure increases to achieve maximum pollution control of waste
streams, some of the criteria previously used to evaluate methods may no
longer apply.
We have grouped the processes under consideration according to the
overall chemical or physical mechanism of their operation:
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1. phase change
2. membrane separations
3. sorption
4. chemical precipitation
This section describes their general nature, experience with their
application to waste water treatment in general, and to textile waste
water in particular (if any). (Cost factors are discussed in Chapter
VIII.)
Figure VII-1 shows the general schematic for a textile waste treatment
process
utilizing advanced treatment. Chemical clarifaction removes suspended
solids, much of the residual COD, some residual BOOS, and certain
elements of color—particularly dispersed dyes. Sand filtration
polishes the clarifier supernatant liquor prior to activated carbon
absorption which removes more COD, BOD5, other color elements of the
waste stream and certain refractory organics such as phenol. At this
stage, the waste stream should contain acceptable levels of all
components except dissolved solids; ion exchange removes these.
Disinfection with chlorine may be required as a final step.
Other advanced treatment methods may replace one or more of the process
steps described. Reverse osmosis removes trace organics—BODS and COD—
, color, and dissolved solids and may replace activated carbon treatment
and ion exchange. Distillation or freezing may replace all tertiary
treatment steps except possibly for chemical clarification for certain
waste streams. Electrodialysis is a substitute for ion exchange.
Distillation Multistage Flash. The multistage flash (MSF
process consists essentially of pumping hot salt, brackish, or
contaminated water through suitable nozzles into a chamber in which the
temperature and pressure are lower than that of the water itself. Part
of the water flashes off instantly as steam which passes through
demisters to remove entrained droplets of impurities and condenses on
tubing cooled by entering feed water. The distilled water drops off the
tubes into a trough and is collected as the product water.
In order to improve the efficiency of the process and recover most of
the heat energy a multi-stage system is preferred in which the latent
heat from the condensation of the steam produced in the evaporation
chamber is used to preheat the cooler feed water flowing in the conden-
ser tubes counter current to the brine in the flash chambers. Thus, the
chief thermal energy requirement is that needed to raise the feed water
96
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c-
o-
PROCESS
REMOVES:
ALTERNATE
PROCESSES:
PRIMARY TREATMENT
Sludge
Suspended Solids
SECONDARY TREATMENT
TERTIARY TREATMENT
Gaseous
Products
4
Activated f narifipr l_jj Chemical Sand Activated fc Ion _ rhiorinarinn
•* Sludge *[ Clarifier hM Clarification * Filtration * Carbon * Exchange * Chlor.nation
Y
Sludge
1. BODS
2. Some Color
3. Some COD
Sludge Sludge Brine
1. Suspended Solids 1. COD 1. Dissolved 1. Disinfection
2. COD 2. Some BODS Solids
3. Some BOD5 3. Some Color
4. Some Color 4. Organics Such as
Phenol
Reverse
Osmosis
Distillation
or Freezing
_
FIGURE VII-1 TEXTILE WASTE TREATMENT
USING ADVANCED TREATMENT
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DRAFT
from ambient temperatures to the temperature of the outgoing brine.
Figure VII-2 shows a simplified flow diagram of two major types
of MSF plants: once-through and recirculation. In a single-purpose
plant the steam needed to heat the brine is supplied by a separate
boiler designed particularly for the water plant. In dual purpose
units, the steam for heating the brine is obtained from the lowpressure
side of an electric power plant steam turbine which operates in
conjunction with the water plant. This permits certain fuel cost econo-
mies but requires coordinated operation of the two plants.
Recirculation of the brine improves thermal efficiency considerably and
all modern MSF plants are of this design.
In a cross-tube plant, the condenser tubes are placed at right angles to
the flow of brine in the flash chambers; consequently, the individual
tubes are shorter than in a plant where the condensing tubes are
installed through the flash stages in the direction of brine flow. In
recent years, however, the long-tube plant has become more popular and
condenser tubes as long as 105 feet have been employed. Plant designs
using tubes up to 360 feet have been proposed but the difficulties in
transportation or fabrication at the site have discouraged their use.
Two types of feed water treatment are generally employed to reduce scale
formation. Frequently a proprietary material is used, containing a
polyphosphate or polyelectrolyte as the active ingredient. These com-
pounds do not prevent scale from forming but rather modify its character
so that it may be easily washed out or dissolved by weak acids periodi-
cally. Often acid treatment is used, with sulfuric acid generally pre-
ferred. The acid is added continuously to the feed water in small a-
mounts to reduce the pH below 7 and decompose the carbonate compounds
that cause hard scaling in the tubes and flash chambers. In many of the
units using acid, the carbon dioxide released by the acid is removed in
a separate decarbonator placed in the feed water circuit after the
reject stages. Otherwise the carbon dioxide is removed with the other
dissolved gases by the steam jet deaerator. In modern units steam jet
deaerators are used to dearate the flash chambers and to produce a
vacuum.
Vertical tube distillation. The vertical tube evaporator
(VTE), a long-tube vertical distillation type of desalting plant, is
second only to MSF type plants in the total volume of water produced
worldwide. The Desalting Plants Inventory Report No. 2 published by OSW
lists 96 VTE plants with a combined capacity of 206,000 cu m/day (54.4
mgd) as compared with 229 MSF plants which produced 554,000 cu m/day
(146.3 mgd) .
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DRAFT
Steam
Brine
Heater
Condenute
To Atmoiphere
Air Ejector
Steam
Stage
Cooling
Seawaicr
Intake
Bfinc
Discharge
A. Croc Tube — Once Through - Plant
Steam
Brine
Hciter
To Atmosphere
1 Air Fjoclor
I pT"l—' St
Coolin
Compensate
Out
Acid and/or Sole
Prevention Treatment
B. Long Tube • Re«irrul,itioii - Acid Treatment - Plant
FIGURE VII-2 SIMPLIFIED FLOW DIAGRAM
OF TOO TYPES OF SINGLE EFFECT MULTI-
STAGE FLASH DISTILLATION PLANTS
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DRAFT
In the climbing-film vertical evaporator, -the most common design, the
brine is maintained at a predetermined level insidetthe vertical tubes,
which are heated externally by the incoming steam in the first effect or
by the hot product vapors in subsequent effects. (See Figure VII-3.)
This
is in direct contrast to a submerged tube type of unit where the steam
is inside and the boiling brine is outside the tubes. The vapors from
the boiling brine rise in the vertical tubes into a vapor chamber and
are led from there into the vertical tube heat exchanger in the next
effect where the heat is given up to the brine circulating in these
tubes.
The resulting fresh water condensed on the outside of the tubes is re-
moved and combined with product from the subsequent effects. The com-
bined product is cooled in a final condenser with feed water. The in-
coming feed water is fed into the first effect and the concentrated
brine flows in the same direction as the vapors. The brine in each
effect circulates either by natural temperature differences or by forced
circulation.
In another modification, known as the thermal recompression evaporator,
part of the vapors from the last effect are entrained and compressed by
expanded live steam from the boiler. The resulting mixture becomes the
heating medium for the first effect. This scheme is particularly
advantageous where high-pressure steam is available as a source of heat
and it can be used in conjunction with a single or multiple effect
vertical-tube evaporator.
Relevance of distillation^ processed to,textile waste treatment
The wastewaters from the textile industry may have a moderately high
concentration of organic chemicals in comparison with the concentrations
in brackish or saline waters. Because organic chemicals may have
appreciable vapor pressures at the temperatures of evaporation, vapor -
liquid equilibrium relationships will determine whether these organic
pollutants can be removed successfully by evaporation. The more
volatile species could easily appear in the condensate where only a
small fraction of the total water has been evaporated. In addition,
wastewater { could be distilled to produce a highly concentrated stream
containing the pollutants. Therefore, removing a large fraction of the
total water will accentuate the steam distillation effect and remove
more organic chemicals, since the amount obtained in the vapor phase is
a function of the concentration in the liquid phase. Consequently, the
application of distillation (evaporation) to wastewaters demands a
thorough knowledge of the physical chemistry of these wastewaters,
especially vapor-liquid equilibria, and the subsequent determination of
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DRAFT
StIMITI 111
Coo liny
Water In
Feed In
W;itci Out
Hrc'.h W.iter
lit \i\K to W.r.tO
FIGURE VII-3 SIMPLIFIED PROCESS FLOW
DIAGRAM, CLIMBING FILM, VERTICAL TUBE
EVAPORATOR
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DRAFT
the quality of the condensate acceptable for reuse since the condensate
presumably would not be disposed of to receiving waters.
In some instances, it might be necessary to treat wastewater
biologically by activated carbon adsorption to insure adequate removal
of organic species. Therefore, a thorough consideration of the entire
process chemistry will be required before one can determine whether
evaporation can be successfully applied to wastewaters containing
biologically active carbonaceous substances. If the wastewater streams
contain very low concentration of organics and high concentrations of
dissolved inorganic salts, the applicability of evaporation is more
readily predicted, being essentially an evaluation of economics.
Evaporation equipment is available; whether it will operate
satisfactorily on wastewater streams that contain high levels of
carbonaceous substances is a moot point. For example, the deposition of
carbonaceous substances on heat transfer surfaces or the occurrence of
foaming could be severe deterrents to the applicability of evaporation.
Carryover of mists, in addition to the steam distillation effects
discussed earlier, could reduce significantly the quality of the water
produced. In many instances, it would be necessary to limit the
fraction of the total wastewater stream evaporated so that concentration
levels in the evaporation system will insure operability.
As with most tertiary treatment methods, there would remain the problem
of final disposition of the concentrated contaminated waste stream.
Freezing Technigues
Description. It has long been recognized that individual ice
crystals formed in chilled impure water are composed of pure water.
Much effort has therefore gone toward the development of practical
processes to take advantage of this phenomenon for the desalination or
purification of water. Attention is presently centered on two types of
equipment. (5.2)
The vacuum freeze vapor compression (VFVC) system has the longest his-
tory. In this type of device, feed water is chilled and exposed to a
slight vacuum. Some of the water vaporizes and the resulting loss of
heat of vaporization causes ice crystals to form in the system. In
other words, the feed water boils and freezes simultaneously.
The ice crystals are separated mechanically from the brine by means of
sieyes and scrapers and transferred to melting chambers. At the same
time the water vapor formed during the boiling-freezing stage is com-
102
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DRAFT
pressed and introduced also to the melting chamber, where it condenses
on the ice crystals. In practice the system is more complicated, with
particular care being required to wash the ice crystals free from feed
water and to maintain the correct temperatures and pressures throughout.
The second type of design employs as the vaporizing constituent a secon-
dary refrigerant which is insoluble in water. Usually, liquid butane
under pressure is bubbled through the feed water, vaporizing, expanding
and causing ice crystals to form. As in the vacuum freeze system, the
crystals are then separated mechanically and washed by liquid butane.
The secondary refrigerant system has the advantage that the equipment
operates at higher pressures and smaller volumes of gas (butane), re-
sulting in less expensive and more reliable pumps and compressors.
Experiences outside the textile industry. A few small VFVC
plants have been erected in this country and abroad for desalination of
seawater, but have not had enough service to develop useful histories.
Their principal advantage appears to be that they are relatively
insensitive to the nature of the chemicals in the feed water and,
because they operate at low temperatures, resist the scaling and
corrosion problems which plague most other types of plants. None has
been used for waste water treatment. The secondary refrigerant system
is still in the pilot plant stage of development.
Experiences within the textileindustry. Neither type of
freezing plant has been used in the textile industry for waste water
treatment.
Applicability. Waste water treatment by freezing might be
attractive to the textile industry because of its tolerance of high
levels of salts, organics, suspended solids and other materials in the
feed water. It can be operated at brine-to-product ratios as low as
about 0.02, and brine concentrations as high as 60,000 mg/1 TDS. This,
of course, considerably reduces the cost of ultimate brine evaporation
or disposal. Unfortunately, there is insufficient service data to
permit firm calculation of maintenance costs and reliability.
Membrane Processes
Introduction. Within the past 5 to 10 years, a number of
synthetic semi-permeable membranes with controlled permeation properties
to salts and macromolecules have become available in quantity. These
have made possible a number of novel waste treatment processes which
were previously laboratory curiosities. In this section we discusstthe
103
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DRAFT
application of three membrane processes to waste treatment and to
textile wastes in particular: electrodialysis, reverse osmosis, and
ultrafiltration.
Electrodialysis relies upon membranes which are permeable to either
cations or anions, and impermeable to the oppositely charged ions.
Salts are removed from solution under the action of an electric field.
Reverse osmosis, conversely, relies upon membranes which are permeable
only to water, and impermeable to salts. Water travels through the
membrane under the action of a hydraulic pressure gradient, rejecting
salt. Ultrafiltration differs from these two processes, in that the
membrane is permeable to both salt and water, but not to macromolecules
or suspended solids. Salt and water pass through the ultrafiltration
membrane under a pressure driving force, while macromolecules and
colloids are held back.
Despite the differences in the basic principles, these three membrane
processes have one important trait in common: at the completion of the
process the original waste stream is split into two components, a high-
volume purified stream, and a low-volume waste stream containing high
concentrations of the original contaminants. At some point, this con-
centrate must be removed from the membrane process, evaporated and dis-
posed of. The exact concentration factor at which the concentrate
stream is removed depends upon the balance between the further cost of
the membrane process and the cost of evaporating this small volume.
This tradeoff must ultimately be considered in the final evaluation of
the cost of the membrane processes for treatment of textil wastes.
The following sub-sections discuss each of these membrane processes in
some technical detail, and their applicability to textile plant wastes.
In most cases, very little direct data on the treatment of such wastes
by membrane processes is available. Their applicability must be extra-
polated from their use in related processes.
General Description. Reverse osmosis for desalinization of sea
water and brackish water has been under extensive investigation since
the discovery in the early 1960fs of high flux membranes capable of re-
jecting salts (VII5.3). Much of the research and development work was
funded by the Office of Saline Water, with a view toward recovering
potable water from sea water. Although this aim still has not been
fully attained at prices competitive with other processes such as flash
distillation, improved technology arising from these programs and
increased commercial interest has resulted in some successful
utilization of reverse osmosis for removal of dissolved salts from
industrial waste streams.
101
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DRAFT
The process of reverse osmosis (Figure VII-a) relies upon the ability of
certain specialized polymeric membranes (usually cellulose acetate or
nylon) to pass pure water at fairly high rates and to reject salts when
saline feed streams are passed at high pressures over the surfaces of
the membranes. The applied hydraulic pressures must be high enough to
overcome the osmotic pressure of the saline feed stream, and to provide
a pressure driving force for water to flow from the saline compartment,
through the membrane, into the fresh water compartment. The cost of
recovering clean water increases with increasing salinity of the feed
stream. (This principle must be explicitly considered when the
economics of salt removal from waste streams is calculated: at some
point the stream will become sufficiently concentrated to make it
cheaper to evaporate the residual brine than to continue reverse
osmosis.)
Figure VII-5 shows a schematic flow diagram of a typical reverse osmosis
system. Feedwater is pumped through a pretreatment section which re-
moves suspended solids (by screening and cartridge filters) and, if
necessary ions such as iron and magnesium which may foul the system.
The feedwater is then pressurized and sent through the reverse osmosis
modules. Fresh water permeates through the membrane under the pressure
driving force, emerging at atmospheric pressure. The pressure of the
concentrated brine discharge stream is reduced by a power recovery tur-
bine, which helps drive the high pressure pump, and then is discharged.
The design of the modules containing the reverse osmosis membranes is
crucial to the efficient operation of the process. As salt is rejected
by the membranes, it concentrates at the membrane surface and results in
a situation known as "concentration polarization," where the salinity at
the membrane surface is many times higher than in the bulk feed
solution. Since the driving force for water transport decreases with
increasing osmotic pressure at the membrane surfacs, concentration
polarization can have a very deleterious effect on water flux.
Concentration polarization can be minimized by high fluid shear at the
membrane surface to aid the back-transport of polarized salt into the
bulk of the process stream. This is accomplished by flowing the feed
stream at high velocities in thin channels (laminar shear) or in wide
channels to produce turbulence (VII 5.7).
Three types of reverse osmosis configurations are currently popular (VII
5.8). The first, known as the "spiral wound" configuration, uses flat-
sheet cellulose acetate membranes wound in a spiral to produce a multi-
tude of thin channels through which the feed water flows under high
laminar shear. This configuration is inexpensive, produces high water
105
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DRAFT
Soutt*. Saiiiloitl f\tvmt\. I
FIGURE VI1-4 PRINCIPLE OF REVERSE
OSMOSIS
106
-------
DRAFT
I L
i±=
_^ Pi ttU-i
FIGURE VII-5 SCHEMATIC DIAGRAM OF
THE REVERSE OSMOSIS PROCESS
107
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DRAFT
fluxes, and consequently efficient use of membrane area. Its major
difficulty is that the resulting thin channels become easily fouled and
plugged, so a process stream must have a very low level of suspended
solids.
The second configuration uses tubular cellulose acetate membranes to
bring about turbulent flow and overcome concentration polarization. The
membrane is formed into a tube—with an inside diameter of about 1 inch,
and the "active" (salt rejecting) face of the membrane on the inside of
the tube—through which the feed stream is recirculated at high
turbulent speeds. Membrane utilization is not as efficient as in the
spiral wound configuration, but there is less trouble with flow
distribution, fouling and plugging. This system can handle highly
contaminated wastes with high concentrations of suspended solids.
Finally, a reverse osmosis system using a multitude of hollow nylon
fibers has shown considerable utility on commercial waste streams. A
bundle of fibers, with the "active" side of the nylon membranes on the
exterior of the fibers, is encased in a module. Feed water is passed at
high velocities between the fibers, and fresh product water permeates
into the interior lumens of the fibers from where it is collected. This
configuration results in rather low utilization of membrane area, but
since the cost per unit area of the membranes is considerably lower than
the cost of the cellulose acetate membranes, the ultimate cost of water
recovery is competitive for low salinity feed streams. This
configuration, like the spiral wound one, is highly susceptible to
fouling by suspended solids, and requires thorough pre-treatment of the
feed stream.
Application to Textile Wastes. The major application of re-
verse osmosis to textile wastes would appear to be in removal of salt
from secondary sewage plant effluent. The technology appears adequate
to reduce the effluent salts to potable levels (less than 200 mg/1).
The process should also result in excellent color removal, and
substantial removal of residual BOD and COD. The major limitation
appears to be cost: for large plants, 19,000 cu m/day (5 mgd) or
greater, costs are 13 to 190/1000 liters (50 to 75
-------
DRAFT
Grease and oil in the feed may also retard fluxes to some degree,
although this effect reportedly is not as great in the tubular
configurations. Additional constraints are imposed by the
susceptibility of the membranes to chemical attack. The cellulose
acetate membranes used in the spiral wound and tubular configurations
can be used only between pH 5 and 9. Thus alkaline streams will need to
be neutralized. Nylon hollow fibers have been used on streams with pH
between U and 11, making these membranes more acceptable for non-neutral
wastes. In addition to treatment of secondary sewage effluent, reverse
osmosis has been considered for a number of other applications in
textile wastes. An experimental hollow-fiber reverse-osmosis pilot
plant operates on the total waste stream from a textile plant (VII 5.9).
This system, which requires extensive prefiltration of the feed stream,
has allowed 80% recovery of the product water, with good color removal.
Data on flux rates, cost, or longevity is inadequate to extrapolate to
the ultimate utility of the process. It is expected that flux decline,
because of suspended solids, may be a problem, and COD may not be
removed adequately.
Another potential application of reverse osmosis is recovery of sizing
materials. Carboxymethylcellulose (CMC) and polyvinylalcohol (PVA) will
both be retained at great efficiency by reverse osmosis, allowing these
sizing materials to be concentrated for reuse. The savings from reuse
of these sizing streams may offset the costs of the smaller plants re-
quired to process just the sizing waste streams.
yitrafiltration.
General description. Ultrafiltration is similar to reverse
osmosis in that it relies on the permeation of water through a semi-
permeable membrane under a hydraulic driving pressure. The distinction
between reverse osmosis and Ultrafiltration lies primarily in the reten-
tion properties of the membranes: reverse osmosis membranes retain all
solutes, including salts, while Ultrafiltration membranes retain only
macromolecules and suspended solids. Thus salts, solvents, and low
molecular weight organic solutes pass through Ultrafiltration membranes
with the permeant water. Since salts are not retained by the membrane,
the osmotic pressure differences across Ultrafiltration membranes are
negligible. Flux rates through the membranes usually are fairly high,
and hence lower pressures can be used than are practical in reverse
osmosis. Typical pressure driving forces for Ultrafiltration are 20 to
100 psi.
nitrafiltration processes face problems of concentration polarization
similar to those encountered in reverse osmosis. However, instead of
109
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DRAFT
salts concentrating at the membranes surface, causing high osmotic
pressures, the concentrating species are usually macromolecules or
colloidal suspended solids which cause a "filter cake*1 to form atop the
ultrafiltration membrane, with a subsequent decline in product water
flux rates. As with reverse osmosis, concentration polarization is
minimized by high fluid shear rates or turbulent flow. Membrane module
designs to minimize concentration polarization include thin channels
tubular designs for turbulent flow, and hollow fiber designs. The
latter have the "active" side of the membrane on the inside of the
fibers, with permeant water collected from inter-fiber spaces.
Membranes may be made from cellulose acetate, polyelectrolyte complexes,
nylon, or a variety of inert polymers. Hence, highly acidic or caustic
streams may be processed, and the process is not usually limited by
chemical attack of the membranes. (VII 5.10)
Applications of Ultrafiltration. Because of costs, ultra-
filtration has been used only when: (1) product water must be of ex-
tremely high quality, completely sterile and colloid-free; or (2) the
waste stream contains a contaminant of value which may be recovered by
ultrafiltration. Illustrative current uses include:
(1) Production of colloid7free water forpharmaceutical use. Ultra-
filtration is used to remove colloids and suspended matter from tap
water. (The water is also subjected to ion exchange to remove
salts.) Costs for ultrafiltration are estimated to be 14*/1000
liters for a 190 cu m/day plant (54*/1000 gallons for a 50,000-
gallon/day plant.)
(2) Recoyery of e1ectrodeposition paint from wa ste str eams. This is
one of the two or three major industrial applications of
ultrafiltration. Electrodeposition plants produce a dilute waste
that contains a significant quantity of colloidal electrodeposition
paints and associated salts. Ultrafiltration concentrates the paint
for reuse, while the permeant water can be reused as rinse water.
Pollution is reduced considerably, and the saving in paints adds up
to 30 per cent, allowing the cost of the ultrafiltration system to
be completely amortized (VII 5.11).
(3) Recovery of whey protein and ^lactose. Whey from cheese fac-
tories has been a major pollutant of streams in cheese producing
areas. Cheese whey contains an extremely high level of dissolved
inorganics (up to 10,000 mg/1 salts) and a very high BOD (U per cent
lactose sugar, 0.5 per cent protein, typically.) With present
legislation, it is no longer possible to dispose of untreated whey
by dumping into rivers, and the quantity and high BOD of the streams
110
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DRAFT
place a considerable load on municipal sewage systems.
Ultrafiltration has been used to concentrate and remove the sugars
and salts from the protein in whey streams, resulting in a valuable
by-product (VII 5.12). The lactose can then be crystallized out,
and reverse osmosis used to desalt the remaining water. This
process has now moved from a pilot plant operation (funded by the
EPA and USDA) to successful commercial operation in several dairies
(VII 5.9) .
Application of Ultrafiltration to Textile Waste Streams. Since
Ultrafiltration does not remove salts and low molecular weight organic
compounds such as dissolved dyes, its utility in textile waste treatment
would appear to be limited.
Concentration and recovery of disperse dyes by Ultrafiltration may be
feasible, but this will by practical only where a single color is in the
waste stream, so that the dye may be reused. Concentration of polymeric
cotton sizing materials (PVA and CMC) is technically feasible since the
UF membranes will retain the polymers and pass the polymerfree water at
reasonable fluxes (VII 5.9). An experimental system at the J, P.
Stevens plant is being used to test the feasibility of PVA concentration
by Ultrafiltration, with the ultimate aim of re-using the sizing
polymer. The membrane in this system is a new experimental "dynamically
formed" membrane based on deposition of organic surfactants on porous
carbon, but the process should be feasible on more conventional UF
membranes at a cost of 13* to 260 per 1000 liters (50* to $1.00 per
thousand gallons) of water removed.
El.ectr.Qdialv.sis
Description. The production of potable water from brackish
waters by electrodialysis is a mature desalting process. Economically,
the process is usually limited to feed waters having total dissolved
solids up to 10,000 mg/1 and more commonly it treats waters with 1000 to
2000 mg/1 solids. It is not practical to reduce the total solids in the
produce water to a few mg/1 as is done in distillation plants; about 200
mg/1 is the highest purity attainable in a practical plant.
The general principles of electrodialysis are as follows. The process
involves the separation of a given flow of water containing dissolved
and ionized solutes into two streams, one more concentrated and one more
dilute than the original, by specially synthesized semi-permeable mem-
branes. Some ion exchange membranes are permeable only to cations;
thus, only positive ions will migrate through them under the influence
111
-------
DRAFT
of an electric field. Other ion exchange membranes, permeable only to
anions, will permit migration of negative ions only.
In electrodialysis, water is fed, usually in parallel, into the compart-
ments formed by the spaces between alternating cation permeable and
anion permeable membranes held in a stack. At each end of the stack is
an electrode having the same area as the membranes. A d-c potential
applied across the stack causes the positive and negative ions to
migrate in opposite directions. Because of the properties of the
membranes, a given ion will either migrate to the adjacent compartment
or be confined to its original compartment, depending on whether or not
the first membrane it encounters is permeable to it. As a result, salts
are concentrated or diluted in alternate compartments. The process is
shown diagrammatically in Figure VII-6 (VII 5.1).
112
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DRAFT
To achieve high throughput, the electrodialysis cells in practice are
made very thin and assembled in stacks of cells in series. Each stack
consists of more than 100 cells. Feed water is first filtered to remove
suspended particulate matter which could clog the system or foul the
membrane and, if required, is given an ion exchange treatment to remove
oxidizing materials such as ferrous or manganous ions which would damage
the membranes. Very high organic levels may also lead to membrane
fouling. The catholyte stream is commonly acidified to offset the in-
crease in pH which would normally occur within the cell, and an anti-
scaling additive may be required as well. An operating plant usually
contains many recirculation, feedback and control loops and pumps to
optimize the concentrations and pH's at different points and thus
maximize the overall efficiency. A typical electrodialysis flow sheet
is shown in Figure VI1-7.
Experience Outside the Textile Industry. Electrodialysis has
been used successfully for more than a decade to convert brackish (2000-
5000 mg/1 TDS) water to potable water ( 500 mg/1 TDS). While this does
not represent a waste water treatment application per se, it can provide
useful reliability and cost data from the some 150 plants which have
been built.
Electrodialysis has also been used successfully to demineralize milk
products (whey) for a number of years and has been employed in a few
cases by the chemical process industry where it is necessary to remove
ionized mineral constituents from process streams (VII 5.13). It has
not been used for treatment of any conventional secondary effluent.
Experience Within the Textile Industry. Electrodialysis has
not been used to treat textile plant wastes. Some efforts have been
made by Ionics, Inc., to investigate its use in dye removal. Unfor-
tunately, because of their large molecular size, dye materials do not
traverse the membranes readily. There may be some possibility of using
electrodialysis to remove dissolved salts from dye solutions, but this
has not yet been demonstrated.
Applicability. The mechanism of the electrodialysis process
limits it to the removal of relatively small, mobile, ionized consti-
tuents from the waste stream. Sodium, potassium, chlorides and sulfates
readily pass through the membranes. Larger ions, and those doubly
charged, such as phosphate, calcium or barium, have limited mobility in
the membranes and tend to remain in the feed stream. There may be some
incidental transport of small dissolved organic species through the
membranes but it is not significant.
113
-------
Cathode
Q
Feed Water
CP
AP
V
cr/
©
CP
V
V
Dilute
Stream
(Product)
Concentrate
Stream
("Waste)
FIGURE VII-6 DIAGRAMMATIC
REPRESENTATION OF ELECTRODIAL YSIS
Anode
CP - Cation Permeable Membrane
AP - Anion Permeable Membrane
All cations in the feed water show
the same behavior as sodium (Na+),
and all anions the same behavior as
chloride (C1-).
-------
S3IHHS NI S5IDVIS N HUM INVld
SISA
Feed
Purr.p
Dilute Bypass
+v
Dilute Booster
Brine
booster
_>_ _. _
X^-^ O ' .- I. e D .
[ Kl_e_--t r-jd'-- ".-!s :
Cathode Hi c- Iroivtt-
Krir.-? HC'-i ri ulation
|Anti-Scale
'Additive
Anti-scale
Dilute
A< id
o
Produc
PUIDD
Product
U'a t e r
,G
Stai-k
.'/ n
Dep.as-
sifier
Sumps
Tl
-------
DRAFT
Suspended solids in the feed stream are undesirable. They may erode the
membranes, plug the small tortuous pathways through which the feed
flows, and foul the membrane surfaces. High levels of organic materials
must be avoided as they may attack the membranes (frequently polystyrene
based) or lead to surface fouling. Thus feed water to the plant should
have a low BOD and COD and these will not be substantially changed by
the process.
If strongly alkaline, the feed stream must be neutralized or rendered
slightly acidic to prevent degradation of the anion membrane, which
usually contains quaternary ammonium groups. Iron and manganese in the
feed water must be removed if their total concentration in the feed
water is greater than about 0.3 mg/1.
Calcium sulfate scale can also accumulate if the calcium concentration
in the brine goes above about 400 mg/1. Addition of a sequestering
agent to the feed permits operation to a higher concentration, but not
above about 900 mg/1. For this reason, the brine rarely constitutes
less than 10 to 15 percent of the feed water volume (VII 5.6).
As the purity of the product water increases, its electrolytic
conductivity decreases. This higher resistance makes it increasingly
less efficient to remove the remaining salt. In addition each stack of
cells in series reduces the salt concentrations by a more or less fixed
percentage. Thus the equipment necessary to remove 250 mg/1 salt from a
500 mg/1 stream is comparable to that required to remove 2500 mg/1 from
a 5000 mg/1 stream. For these reasons, most plants today do not produce
produce water at less than 500 mg/1 and very few operate as low as 200
mg/1.
sorption systems
Introduction. This group of advanced waste treatment processes
is concerned with methods in which the waste water is contacted with a
material which sorbs components of the water. The material is usually
regenerated and the sorbed material ejected into a gaseous or more
concentrated liquid waste stream (Figure VII-8) . The concentrated
liquid waste stream is normally converted to a solid waste by
evaporation. Such processes include adsorption on activated carbon and
ion exchange.
Treatment by Activated Carbon
Physical Principles. Activated carbon is a commercially
available and particularly versatile absorbent (VII 5.14) primarily
116
-------
Waste
Water
generated
rbent
Make
up
Sorbent
Water Sorbent
Contactor
Sorbent
Regeneration
Regeneration 1 [_Heatfo
Reagent Stream i ' Regener
Purified
Waste
Water
Spent
Sorbent
Gaseous Waste
^ ,-x"^
Concentrated _ .
Waste Stream " Trc°tment D.sposable ^
of Waste Stream Waste Product
(Usually Solid
r
ation
Sorbent
Purge or
Losses
VII-8 SCHEMATIC OF SORPTION PROCESS
FOR WASTE TREATMENT
-------
DRAFT
because of its relatively low cost (22 to 110*/kg or 10 to 50*/lb) and
large surface area (about 112 lectares per kilogram or 126 acres per
pound) which relates directly to its capacity for adsorbed material (0.7
to 0.9 kilograms of adsorbed material per kilogram of carbon).
The most popular form of activated carbon is the granular, which is
easily handled, deposits the minimum of fines into the water stream, and
may be regenerated by heat (or in specialized applications by chemical
streams) with less than 10% loss per cycle (VII 5.15). However,
attempts are being made to develop techniques for the use of powdered
carbon (VII 5.16), which is considerably less expensive (about 22*/kg or
100/lb) than granular carbon (66*/kg or 30*/lb) but which is difficult
to separate efficiently from the waste water and regenerate.
Activated carbon, while acting largely as a general absorbent, shows
some selectivity (VII 5.17) :
Strongly Absorbed Weakly absorbed
weak electrolytes strong electrolytes
sparingly soluble materials very soluble materials
high molecular wt. compounds low molecular wt. compounds
The amount of a given material absorbed is a function of its chemical
nature, the amount in solution, the pH and the temperature. To a first
approximation, adsorption follows a characteristic Freundlic type iso-
therm.
x/M = kCl/n
where: x is the amount of material adsorbed
M is the weight of adsorbent
C is the remaining concentration of desorbed material
k and n are constants that depend on the adsorbent, pH and
temperature
Typical adsorption capacities of activated carbon at different residual
COD levels are illustrated in Figure VII-9.
Process Design. Several types of water carbon contactors have
been proposed and utilized. These are summarized schematically in
Figure VII-10. Usually one or more fixed bed columns are linked in
parallel Carbon capacity is utilized more efficiently by placing several
fixed bed columns in series, the spent upstream column being replaced
118
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DRAFT
with a regenerated column at the downstream side as appropriate. A
recent, more efficient development is the use of moving bed systems.
The carbon is usually regenerated in multiple hearth furnaces; in some
cases, such as in the adsorption of phenol, partial regeneration may be
achieved by chemical treatment (VII 5.18). A schematic of a treatment
process including thermal regeneration is illustrated in Figure VTI-11.
The detailed design of actual plants is discussed in the next section.
Use of Carbon Absorption in General Applications. The En-
vironmental Protection Agency has undertaken detailed studies of the use
of activated carbon for the tertiary treatment of municipal wastes -
primarily at Pomona, California and Lebanon, Ohio (VLL 5.19). The
Pomona plant has been run for over four years and deserves detailed
description (VII 5.20).
The plant has a capacity of 1100 cu m/day (0.3 mgd) and is a four-stage,
fixed-bed, granular activated carbon plant. The general design is
illustrated in Figure VII.12. The carbon is periodically backwashed to
remove entrapped suspended solids (the secondary effluent then need not
be pretreated) and regenerated when necessary (after a steadystate
adsorption capacity of about 0.4 to 0.5 kilograms of COD per kilogram of
carbon has been reached) in a vertical six-hearth furnace. Carbon
losses averaged 8 1/2 percent per cycle. One complete cycle of the
12,200 kilograms (26,800 pounds) of carbon in the plant is achieved each
year of operation.
The effectiveness of the plant in improving water quality is illustrated
in Table VTI-2.
119
-------
DRAFT
1-0
•Dj
t)
•Ol
" .
P
U|E
dt
E|
x-x
xlZ
0-1
0-01
0-1
1-0 10-0
(C) Residual COD cone, (ppm)
100-0
FIGURE VII-9 COD ISOTHERMS USING
VIRGIN CARBON AND DIFFERENT SECONDARY
SEWAGE EFFLUENTS
(after Masse, 1967).
-------
DRAFT
a) Columns in Parallel
b) Columns in Series
Carbon
Influent
Influent Effluent
d) Gravity Carbon/Sand Filter
Carbon
c) Moving Bed Column
FIGURE VII-10 SCHEMATIC OF ACTIVATED
CARBON WATER CONTACTING SYSTEMS
tJ-t
-------
DRAFT
Regenerated
Carbon
Influent
•*—3
Carbon
Columns
Effluent
5
Regenerated
Carbon Storage
Regenerated Carbon
FIGURE VII-11 SCHEMATIC OF AN ACTIVATED
CARBON SYSTEM INCLUDING THERMAL
REGENERATION
-------
DRAFT
CHLORINATION
(OPTIONAL)
SECONDARY
EFFLUENT
STORAGE
TO
PlilMARY
CLARirif.RS
^1=3,, .,
f ! 1:
;k f\
-------
DRAFT
Table VII-2 Carbon Adsorption Pilot Plant;
Average Water Quality Characteristics
(June 1965 to July 1969)
Parameter
Suspended solids mg/1
COD mg/1
Dissolved COD mg/1
TOC mg/1
Nitrate as N mg/1
Turbidity (Jtu)
Color (Platinum-Cobalt)
Odor
CCE mg/1
BOD mg/1
Source: Reference VII 5.20.
Influent
9
43
30
12
8.1
8.2
28
12
—
3
Effluent
0.
10
8
3
6.
1.
3
1
0.
1
6
6
2
026
124
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DRAFT
About 75% of the influent COD is removed, and the values of most other
parameters such as suspended solids, turbidity, color, odor, and BOD are
reduced to insignificant levels. The effluent water had an average dis-
solved COD of 8 mg/1.
Another activated carbon plant studied by the EPA is part of the
advanced waste treatment facility at the District of Columbia's advanced
waste treatment facility (VII 5.21). Following lime precipitation,
filtration and water stabilization, the secondary effluent is passed
through five pressurized activated carbon columns in series at a rate of
190 cu m/day (50,000 gallons per day). When the preceding clarification
was operating efficiently, up to 75 percent of the TOC was removed by
the carbon adsorption system. Problems developed because the carbon
entrapped grease and bacterial activity produced stemies on the carbon.
(In other work, this was prevented by addition of biocides). Anaerobic
conditions developed leading to hydrogen sulfide production. In
addition, blinding, plugging, and channeling accompanied by severe
pressure drops were experienced. The carbon had to be replaced before
saturation, at a loading of only 0.133 kilograms TOC/kilogram carbon.
Two more specialized applications of activated carbon treatment of waste
waters are worthy of mention. The first, moving-bed, single-stage
carbone adsorption unit, was used to recondition brines used in olive
processing in the central Valley of California (VII 5.22). The unit had
a capacity of 6.8 to 47.7 cu m/day (1,800 to 12,600 gallons per day).
Its effectiveness is illustrated in Table Vli-3.
Table VII-3. Brine Reconditioning
Influent Effluent
pH U.O-U.3 U.2-8.8
Acidity 0.3 0.02-0.39
Color 75-100 70/5
NaCl 5.5 5.2-5.5
SS 200-286 16U-220
COD 18,000 5,000-16,500
125
-------
DRAFT
178
280
70
115
-
_
81.1
49. 0
81.7
47.8
99.4
99.5
In the second exploratory studies (VII 5.18) in Conway, North Carolina,
the feasibility of using activated carbon treatment to reduce phenol
levels and coloration of a waste stream to insignificant levels was
demonstrated. The influent was dark red and contained 2,500 mg/1 of
Table VII-4
Dyehouse Treatment
Wastewater Plant Reduction
Influent Effluent
COD - mg/1 at 8.5 gpm ft2 945
at 15.6 gpm/ft2 550
TOC - mg/1 at 8.5 gpm/ft2 378
at 15.6 gpm/ft2 220
colour - at 8.5 gpm/ft2
at 15.6 gpm/ft2
phenol. The carbon was regenerated by washing with sodium hydroxide
solution. Activated carbon treatment was also used successfully at Lake
Tahoe to produce drinkable water from secondary effluent (VII 5.23). A
28,000 cu m/day (7.5 million gpd) unit operated at a cost of 6*/1000
liters (230 per 1000 gallons).
Experience with the Use of Activated Carbon on Textile Wastes.
The use of activated carbon to treat textile wastes was pioneered at the
Stephen-Leedorn Carpet Mill, Southampton, Pennsylvania (formerly
Hollytex Carpet Mills) in association with Calgon Corporation (VII
5.2ft). Of the raw waste from the dyeing and rinsing plant, 80 percent
was treated and reused. The remaining 20 percent, which contained high
dye concentrations, could not be treated economically, however. A
schematic of this plant is given in Figure VII-13. Capacity of the
system was 1900 cu m/day (500,000 gallons per day) and it utilized
22,700 kilograms (50,000 pounds) of Filtrasorb 400 granular activated
carbon. The carbon was regenerated by heating it in a furnace.
The Fram corporation, supported in part by the EPA, has done
considerable work in pioneering its unique activated carbon system in
which regeneration is accomplished by backwashing the absorbed organic
126
-------
DRAFT
material into an aerobic biological treatment unit (vii 5.24-5.28), as
shown schematically in Figure
127
-------
DRAFT
After encouraging results in a laboratory unit operating on synthetic
textile waste water, a pilot system was installed at C. H. Masland and
Sons carpet yarn fibre dyeing plant in Wakefield, Rhode Island. The
flow diagram of the pilot system, which has a capacity of 190 cu m/day
(50,000 gpd) , is shown in Figure VII-15.
Three basic problems were encountered:
1. The waste was not equalized so sugrges of dye concentration
sometimes overload the carbon beds.
2. Batch adsorption required acceptance of the full hydraulic load
of the dye-house discharge, shortening adsorption times.
3. The biological culture was subject to er atic feeding. These
difficulties forced the systems to be redesigned, as shown in Figure
VII-16.
Cone Mills Corporation of Greensboro, N.C., has been conducting a range
of studies on the treatment of dye waste waters (VII 5.26). The company
encountered only partial success in the use of carbon for effluent
polishing following biological treatment. Anthracite-based media proved
unreliable in removing all types of color contamination; bone char
proved successful but cost about $2.20 per kilogram ($1.00 per pound)
compared to 660 per kilogram (30t per pound) for the former materials.
Hecknoth reported a 50 percent reduction of organics in certain dye
wastes using activated carbon.
Our field work yielded several further instances of the use of activated
carbon adsorption for the treatment of textile wastes, particularly in
regard to color renewal. Milo Industries, Bloomsbury, Pa., operates a
closed dye cycle using alum, dicetomaceous earth, and carbon to yield a
color of less than 50 units. A series of trials carried out to evaluate
activated carbon adsorption for color removal (VII 5.30) gave somewhat
erratic results; despite early hope only a small amount of color was
removed. This has been confirmed generally throughout the industry.
The consensus (VII 5.32) appears to be that while color can be removed
by activated carbon, some elements (particularly the dispersed dyes) are
not adsorbed. Chemical coagulation perhaps supplemented by activated
carbon adsorption remains the best method.for the dispersed dyes, while
carbon adsorption alone may be adequate for dissolved dyes.
To summarize, activated carbon treatment is a common technique in indus-
trial processes, has been evaluated in some detail and has been success-
ful in treating secondary effluent following biological treatment of
-------
RECLAIMLC)
RECLtlMEO
'WATER
/
\COOur.'G
TO-.VER
RECLAIMED
VMUft
/TO f'l.Af
MOVING OtO
REACTIVATED GRANULAff CARSON
no1, urirx C'inpci MILI
PLANT
r
PLANT >?ASTf w.ui;
FROM ovtii.'G c. CASING
00% TO PATCH ;;; CLA..-,'.II'.'.V
SYSTL'.1.
!0 OSiAIN
-«3-
SLURRY
PUMP "
->••
FUKMACE
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QUfNCH
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SI'KMT
ACTIVATf.O CAIMCN
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EUUCTOa
FURNACE
\VAirj ;
(500,000 GALLON PER DAY)
HOLl.YTCX CAfJJ'CT I/.ILLS
fi, Po.
o
TO
FIGURE VII - 13
-------
DRAFT
—i
FIGURE VII - 14 SORPTION
REGENERATION
130
-------
QL.
Q
FIGURE VII-15 SCHEMATIC FLOW DIAGRAM
-------
ADSORPTION COLUMN'S -SYSTEM I
FROM
DYCKOUt!:
EQUALIZATION
YANK
ADSORPTION COLUM!vS-r>YS~rK 2
Q
FIGURE VII-16 SECOND GENERATION
SYSTEM
-------
DRAFT
municipal waste water. Some successful experience also has been accu-
mulated in the treatment of textile wastes. Only the advanced process
is suitable for reducing low-level organic contamination, but it affects
the levels of dissolved ionic solids very little. Its chief difficulty
concerns the removal of color; some dispersed dyes are not absorbed to
any great extent. The process needs to be evaluated for any given
process stream.
Ion Exchange
General Description. Ion exchangers are solid materials, in-
soluble in electrolyte solution, which are capable of exchanging soluble
anions or cations with electrolyte solutions. For example, a cation ex-
changer in the sodium form, when contacted with a solution of calcium
chloride, will scavenge the calcium ions from the solution and replace
them with sodium ions. This provides a convenient method for removing
the "hardness" from waters.
Ion exchange can also be used for total salt removal from waste streams,
by employing a series of beds of exchangers followed by anion cation ex-
changers. The cation exchanger is used in its "acid" form, exchanging
hydrogen ions for the cations in the stream. The anion- exchanger is
used in its "base" form, exchanging hydroxyl ions for the waste stream
anions. The hydroxyl and hydrogen ions thus liberated from the ion
exchanger recombine to form water, and thus replace the salts in the
stream by pure water.
An example is a stream that contains sodium chloride. The reactions may
be presented as follows, where RA is the solid anion exchanger, and RC
is the cation exchanger:
RA-OH + NaCl
RC-H + NaOh
RA -Cl
NaOH
RC-NA + HOH
The exchange of ions on ion exchangers is stoichiometric and usually re-
versible. Thus, after the ion exchanger becomes saturated with the con-
taminant ion, it can usually be "regenerated" by flushing with a concen-
trated solution of its original ion. Therefore, in the example quoted
above, the cation exchanger would be regenerated with a concentrated
caustic solution (resulting in a waste regenerate stream of concentrated
Na2SOi|) . The waste regenerate streams are usually quite concentrated
and can be disposed of economically by simple evaporation.
133
-------
DRAFT
Many natural and synthetic materials can act as ion exchangers (VII
5.33). Various alumosilicate minerals with cation exchange properties
are known. Clays and glauconites carry exchangeable counter ions, and
certain natural and modified coals have been used as ion exchangers.
The most important class of ion exchangers, though, is the organic ion-
exchange resins made from cross-linked polyelectrolytes. The exchanger
exchanges the counter ions to the fixed charges on the polyelectrolyte.
These resins are insoluble but swell to a limited degree, allowing ions
from solution to penetrate into the gel matrix formed by the swollen
polyelectrolyte.
They are conventionally used in particulate form in packed beds. The
ion exchange behavior of the resins depneds on the nature of the fixed
ionic groups, with the exchanger preferring those ions which strongly
associate with the fixed (bound) ions.
One of the major advantages of the synthetic resins is the wide ranges
of ion exchange properties which can be built into them, allowing con-
siderable latitude in the designing of processes. These exchangers have
the additional advantage of being capable of absorbing non-ionic organic
solutes from solution (VII 5.33). This sorption is reversible in that
the constituent can be removed by flushing with strong caustic.
disposal of this organic-laden caustic stream then presents an addition-
al problem which may prohibit its use.
General Applicability. In general, ion exchange processes are
limited by the selectivity of the exchanger for the contaminant ion over
its own counter ion. Divalent ions such as calcium and magnesium in
general have high affinities for the ion exchange resins, and can there-
fore be removed with extremely high efficiencies. In general, also, ion
exchange is less efficient than electrodialysis or reverse osmosis for
high concentration streams. An upper limit frequently given for effi-
cient removal of ions by ion exchange is 200-500 ing/1 (VII 5.34), but
others quote efficient cleansing of 2500 mg/1 streams at costs less than
that for electrodialysis or reverse osmosis (VII 5.35).
Recently, a new form of organic ion exchange resin has been developed
which may allow economical de-ionization of waste streams at dissolved
salt levels of 1000 to 3000 mg/1. This "Desal" process is based upon
the discovery that certain weakly basic anion exchange structures can
form the bicarbonate salt with solutions of carbon dioxide, and also
have a favorable chloride-bicarbonate selectivity coefficient (VII
5.31). The process relies on a series of three ion exchange beds.
-------
DRAFT
The first, which is the alkalization unit, consists of a weakly basic
exchanger in the bicarbonate form. When it contacts an electrolyte such
as Nad, the following reaction occurs:
I (R-NH)HC03 + NaCl (R-NH) Cl + NaHC03.
The second bed, containing a weak acid cation exchange resin, acts as
the "dealkylization" unit:
II R-COOH + N3HC03 R-COONa * C02 + H20.
The third unit, which is the carbonate unit, contains a weakly basic
anion exchanger, similar to the exchanger in the first unit, but in
the free base form, and acts as the carbonic acid absorber, resulting
in an effluent free salt:
III R-N + H20 + C02 (R~NH)HC03.
Upon completion of the above cleansing cycle, the alkylization unit
(Unit I) is regenerated to the free base form with ammonia, caustic or
lime. The dealkylization unit (II) is converted back to the hydrogen
form by regeneration with inexpensive mineral acids. Since the car-
bonation unit is already in the bicarbonate form, the flow pattern is
reversed for the next cycle, and the process repeated. A flow sheet
illustrating the process is shown in Figure VII-17.
Typical experimental data from such a process are shown in Tables VII-5
to VII-8 for a number of different waste streams. This process has also
been operated successfully at the polot plant scale on brackish water of
100 mg/1; the concentration was reduced to a final effluent of 20 to 30
mg/1, at an operating cost estimated to be equivalent to a cost of a
3785 cw m/day (1-mgd) plant of 5.3*/1000 liters (20£/ 1000 gallon)
(1970) and a total capital investment for a 3785 cu m/day (1-mgd) plant
of about $250,000 (again in 1970). A commercial plant achieving similar
results was operating in the United STates for several years.
The major problem with this process appears to be the irreversible
degradation of the weak base resins, which may limit their long-term
stability and the ultimate economics of the process.
135
-------
DRAFT
H,SO.-
NH,
Inhutnt •
-H-
•H-
1BA-M
o
-M- -H
X N
0
OHmtMc
ttQUMCl I
CHtUlCAl KIACIION IN UNIT NO
-M-
0
the chemical Symbols r
l»l 10 t
I MCO.-.0 H-.N. 011 ...HCO, 1 ' ' V."«,'
J CI-.OH Nl-. H MCO, «occu".na""~
3 OH-»HCO, H-»NJ MCO,-»CI
FIGURE VI1-17 THREE-UNIT DESIGN
-------
DRAFT
Table VI-5 Composition of Untreated and
Desal Ion-Exchange Treated Acid Mine Water
Constituent Concentration (mg/1 as CaCO3)
Untreated Treated
pH 3.1 8.5
Ca 961 290
Mg 480 10
Fe 895 0.1
Al 556 0.1
Mn 91 0.1
SO4= 3,104 100
HCO3- 200
Source: Reference VII 5.34.
137
-------
DRAFT
Table VII-6 Modified Desal Process for Renovation
of Steel Mill Pickle Rinse Wastes
Constituent
Wastewater
resist., ohm. cm.
Source: Reference VII 5.34.
Modified DESAL
treated waste
mg/1 as CaCO3
Na
K
ca
Mg
Fe
Al
Mn
Acidity (H2S04)
pH
Electrical
42
4
73
35
122
1
2
1,160
1.6
175
35
4
11
22
0.1
1
0.1
None
8.0
4,000
139
-------
DRAFT
Table VII-7 Modified Desal Process for
Renovation of Tin Plating Rinse Water
Treated Water
After After
Constituent Wastewater Amberlite IRA-68 Amberlite IRO84
(mg/1 as CaCO3J
TDS 2,350 875 50
Na 893 872 50
K 1 1 0
Ca 7 2 0
Mg 3 0
Fe 15 <1 <0.1
Al 6 <1 <0.1
Mn <1 <1 <0.1
Sn 1,180 <1 <0.1
Cu <1 <1 <0.1
HC03 0 875 50
pH 3 8.5 6.5
Source: Reference VII 5.3U.
140
-------
DRAFT
Table VI1-8
Typical Results Achieved with counter
Current Ion Exchange
Water analysis, mg/1
Calcium, mg/1 as CaCC^S 92
Magnesium mg/1 as CaCOjJ 10
Sodium, mg/1 as CaCO3 146
Bicarbonate, mg/1 as CaCO3 191
Chloride, mg/1 as CaCO3 ~ 55
Sulfate, mg/1 as CaCO3 2
Si02, mg/1 as SiO2 " US
Deionization Results
Resin
Regenerant
Regenerant dosage
Service flow rate
Effluent TDS
Effluent SiO2
Operating capacity
Cation Exchanger Anion Exchanger
Duolite C-20
H2SOU
36.4~kg/m3
(2.25 Ib/cu ft)
19 l/sec/m«
(28 gpm/sq ft)
11.0 kgr/cu ft
(as CaCO3)
Duolite A-104
NaOH (amb3 temp.)
36.a kg/in'
(2.25 Ib/cu ft)
19 l/sec/m«
(28 gpm/sq ft)
0.2 mg/1
5 mg/1
11.5 kg/cu ft
(as CaCO3)
Source: Reference VII 5.35.
More conventional ion exchange resins have been used for the
desalination of brackish water. A polot plant operation at Pomona,
California has reduced the salinity of tertiary sewage from 1500 to 250
mg/1 with an estimated cost (based on a 37850 cu m/day or 10-mgd plant)
reported to be 2.6 to 6.10/1000 liters (10-230/1000 gallons). (The
former figure is probably unrealistically low, since the cost of
regeneration chemicals alone, based on 100 percent efficiency of
utilization of ammonia and sulfuric acid is over 4*/1000 liters or
15^/1000 gallons) .
-------
DRAFT
The National Cannera Association ran another pilot plant study for the
EPA on reducing the salinity of food processing waste water by ion
exchange (VII 5.36). It was found possible to reduce the salinity of
process streams from 600-6000 mg/1 NaCl to an ultimate salinity of 100-
200 mg/1 for a cost estimated to be (260/1000 gallons) (1970). The
resins were regenerated with calcium hydroxide. It was estimated that
the waste regenerate solution could be made at least 1000 times more
concentrated than the feed solution.
Recently, countercurrent ion exchange (in which regenerate flow is in
the opposite direction from feed water flow, see Figure VII-18) has
begun to make an impact on American ion exchange technology (VII 5.35).
This
process allows more efficient use of regeneration chemicals, and there-
fore significantly reduces cost and pollution by regeneration waste
streams. Apparently, European manufacturers of ion exchange equipment
have recognized the savings for some years and have incorporated the new
technology into their systems. It has been predicted that this
technology whose success relies upon novel methods of preventing
fluidization of the ion exchange resin particles during back flow, will
soon become dominant in U.S. markets also, and will lower the cost of
ion exchange use. Typical operating data on such a system are shown in
Table 4. It is predicted that the cost of reducing the salinity of
waste water containing 1000 mg/1 NaCl to 250 mg/1 will be 10 to 120/1000
liters (UO-U50/1000 gallons), including amortization of equipment, labor
costs, chemicals, etc.
Applicability to Textile Wastes. Direct data on the applica-
bility of ion exchange to textile wastes is scarce. Extrapolation of
data from other waste streams is therefore necessary. It would appear
that the major application of ion exchange to textile waste treatment
would be to reduce the dissolved solids level of the affluent from the
secondary treatment plants or the effluent from other operations such as
electrodialysis or reverse osmosis. (Synthetic organic ion exchange
resins have also been used as absorbers for non-ionic dyes, but the
process is inefficient, and the cost $5/1000 liters over ($20/1000
gallons) impractically high). The dissolved solids levels of the secon-
dary sewage effluents (ca. 1000 mg/1) would appear to be in the proper
range for effective use of ion exchange. Costs for a 500 percent
reduction of this salinity, assuming no other complications, would be
expected to be about 120/1000 liters (150/1000 gallons) of product
water, not including the cost of evaporating the concentrated regenerate
waste stream. This latter is estimated to be of the order of 3 to 5
liters of concentrated waste saline per 1000 liters of feed water.
142
-------
DRAFT
CO-CURRENT COUNTERCURRENT
WATFR W/VTfR
V/ATCR
SERVICE
nEGENERANT
SERVICE
REGf.NCKANT
REGENERATION
ntCLKi RANT
REGENERATION
FIGURE VII-18 CO-CURRENT AND COUNTER-
CURRENT OPERATION IMPLIES SERVICE IN
ONE DIRECTION AND REGENERATION IN THE
OPPOSITE DIRECTION. SERVICE CAN BE
DOWNFLOW AS IN (A) OR UPFLOW AS IN
(B).
-------
DRAFT
One additional advantage of ion exchange is applicable to highly
alkaline textile waste streams: neutralization combined with ion
removal. For example, if the effluent is sodium hydroxide instead of
the sodium chloride effluent quoted in the original example in this
article, the cation exchanger alone may be used, resulting in the
process:
RC - H + NaOH RC - Na + H20
Thus it may be advantageous, where possible, to leave the alkalinity in
the hydroxide form (rather than carbonating it), and removing it by ion
exchange.
Several unknowns complicate the application of ion exchange to textile
waste streams. A major limitation is that ion exchange is effective
only in the removal of dissolved ions from the solution. Thus, many
other waste treatment procedures (such as reverse osmosis) may remove
the ions in the process of removing other materials such as suspended
solids, rendering ion exchange necessary.
The quality of the waste stream necessary to make ion exchange feasible
is also a major factor in its usefulness. The level of suspended solids
in the waste stream can have a considerable deleterious effect on the
long-term operation of the ion exchange columns. It will therefore
probably be necessary to pre-filter suspended solids down to a level of
20-50 mg/1 before allowing the water to enter the ion exchange columns.
Any oxidizing agents in the waste stream (e.g., hydrogen sulfide) will
have an adverse effect on the life of the cation exchangers, while
organic constituents may shorten the life of the anion exchange resins.
It appears, however, that the projected costs of ion exchange for tex-
tile waste clean-up are sufficiently low to justify a study of the
parameters to determine long-term applicability.
ghemical clarification
Suspended solids are a significant element of raw textile mill waste
water. The larger components such as lint are readily removed by
screens prior to entering a waste water treatment process. Residence in
a clarifier permits other smaller yet macroscopic particles to settle as
a sludge. Following activated sludge treatment and sludge removal in a
further clarifier, the waste water still contains a variety of
microscopic suspended solids. These may be removed by chemical
clarification methods, which, in addition, have been found to be effec-
-------
DRAFT
tive for color removal. Chemical clarification is rarely used prior to
activated sludge treatment.
Physical Principles. Textile wastes typically contain a
complex mixture of suspended solids, mostly of organic composition, with
particles ranging from 0.01 m up to filterable sizes. They include
color bodies, proteins soaps, fibers, mineral fines, oil and grease.
These suspended solids have deleterious effects on the other advanced
waste treatment processes used in tertiary treatment of waste streams;
they load secondary treatment plants, blind sorbent beds and deposit on
membrane surfaces. In themselves, they contribute undesirable
properties to the waste water — suspended COD, turbidity, color, etc.
The smaller particles are virtually ulfilterable except by expensive and
complex procedures and cannot be settled. (A 1-micron particle takes
one hour to fall 1 mm in solution; a 0.01-micron particles takes more
than one year.)
In addition to the obvious difficulty of removing small particles, the
suspensions are stabilized by two effects: hydration and electrostatic
charge. Most such particles adopt a negative charge and are prevented
from coalescing to the larger, more easily removed particles by elec-
trostatic repulsion. Neutralization of these charges destabilizes the
system and leads -to coagulation and precipitation or easier filtration.
This process is the basis for chemical clarification.
Neutralization and electrostatic charge are generally accomplished by
adding coagulants that contain multivalent cations. These include:
aluminum sulfate
ferric chloride
copperas (a mixture of ferric chloride and ferric sulfate
prepared by chlorinating ferrous sulfate)
ferrous sulfate
ferric sulfate
sodium aluminate
The multivalent cations A1+++, Fe+++ and Fe++ are strongly hydrated and
hydrolyzed, forming acidic solutions that contain hydroxylated positive
ionic pieces. Sodium aluminate, on the other hand, forms a strongly
alkaline solution and is sometimes used in combination with aluminum
sulfate to improve the resulting floe.
A subsidiary mechanism which operates during flocculation in waste water
may also remove certain polluting species: the formation and settling
of the precipitate may absorb and sweep out other water components
115
-------
DRAFT
responsible for color, CODr -turbidity, BOD, etc. In addition to the
reagents listed abobe, lime has been used for this purpose.
Addition of these coagulants to the suspended solids and colloidal
substances produces a floe which is allowed to settle in a clarifier
using gentle agitation. It is important to dissipate the coagulant
throughout the waste water as fast as possible; flash mixing at point of
entry to the clarifier is normally used.
The correct coagulant dose for a specific waste water and particularly
the precise pH for maximum effectiveness must be determined
experimentaly for a given waste water. Unfortunately, the optimum
values of these parameters may not be the same for different components
of the waste water; thus turbidity removal mayddemand an operating pH
different from that needed for color removal.
A second step in chemical clarification may be needed to satisfactorily
separate the suspended floe from the clear supernatant liquor. This
involves the addition of coagulant aids which act to create larger,
tougher floes that are more amenable to sedimentation or filtration.
Activated silica has been used for many years; more recently, water
soluble polymers, usually polyelectrolytes, have been used successfully
for this purpose. They are available in anionic, cationic, or neutral
form to treat floes of differing electrostatic charac eristics.
Experience in General Waste Water Treatment. Coagulation and
flocculation is a widely used technique in waste water treatment and in
the preparation of potable water. Costs typically range from 1-5*/ 1000
liters (5 to 20^/1000 gallons).
Experiencerinjthe Textile Industry. Chemical clarification has
frequently been used in the treatment of textile waste (VII 5.32, VII
5.38-5.42). Apart from its use to remove suspended solids, it has found
particular promise in the removal of troublesome disperse dye particles
which are generally not absorbed by activated carbon. A description of
some typical experience in the textile industry will illustrate the
usefulness of the process.
In 1949, a two-stage flocculation process using ferric sulfate as a
coagulant was used to treat the combined wastes of a wool scouring and
dyeing plant in Glasgow, Virginia (VII 5.13). A total of 950 cu m/day
(250,000 gpd) was treated at a capital cost of $380 (1949 dollars) per
1000 liters ($1,450 (1949 dollars) per 1000 gallons). No operating
costs are given. BOD of the combined wastes was reduced by 60 percent
and suspended solids by over 90 percent.
146
-------
DRAFT
Coagulation was also used successfully in waste water treatment at a Dow
Chemical Company acrylic fiber plant in Williamsburg, Virginia (VII
5.44). The capacity of the plant was 1840 cw m/day (486,000 gpd) .
After primary clarification, the waste is treated with copperas coagu-
lant with pH adjustment. (The wastes contained zinc, which was pre-
cipitated as hydroxide at these high pH levels.) Zinc removal was
consistently above 99 percent so effluent levels were below 1 mg/1.
In Israel, experimental results showed (VII 5.48) that flocculation with
alum and filtration would reduce color by 95% and turbidity by 97% in a
highly colored simulated waste water. Performance was shown to be a
strong function of pH and alum dosage; maximum reduction of color levels
and turbidity did not necessarily occur at the same pH value. The
dependence of color removal on pH is shown in Figure VII-19. Cationic
poly
electrolytes were found to be effective coagulant aids, but only at very
high doses (about 30 mg/1).
The treatment of wool processing effluent using coagulants has been dis-
cussed by Stewart (VTI 5.49). Calcium chloride coagulation was used in
a plant of patens and Baldwins Ltd, Darlington, England. Addition of
2,000 mg/1 of calcium chloride followed by filtration reduced a BOD of
15,000 to 30,000 mg/1 to 2,700 to 3,800 mg/1, suspended solids of 20,000
to 32,000 mg/1 to 1,000 mg/1 and grease levels of 17,000 to 20,000 mg/1
to 50 mg/1. But the cost was over $1.30 per 1000 liters ($5 per 1,000
gallons) in 1964.
The Wool Industries Research Association in Leeds, England, developed
evidence that copperas coagulation could be used in combination with
lime followed by filtration to achieve almost as good results as calcium
chloride coagulation. A 1971 estimate of the cost of this process
yields a value of over $1.80 per 1000 liters ($7 per 1000 gallons) in-
cluding plant, chemical and operating factors.
The cost of ferric chloride used as a coagulant has been estimated as
0.8^/1000 liters (3*/l,000 gallons) (VII 5.24) to reduce COD by 70 to
90% and to remove 99.9 percent of bacteria and 70 percent of the tur-
bidity.
In a review of treatment methods for dye waste waters (VII 5.26), it was
reported that the most successful coagulation technique for color
removal consisted of the use of alum or a combination of alum and a
147
-------
DRAFT
FIGURE VI1-19 REMOVAL OF COLOR FROM
AERATED WASTES AS A FUNCTION OF pH
AFTER FLOCCULATION
-------
DRAFT
cationic polyelectrolyte. Treatment of wastes before and after activa-
ted sludge treatment was studied; in general, less chemical requirement
was found prior to biological treatment. Mixed liquor treated with 150
to 250 mg/1 alum, 10 mg/1 lime and 20 mg/1 cationic polymer produced an
effluent color g 15 (pt/Co scale) wwith zero suspended solids, but the
chemical cost alone was 2.1 to 2.6^/1000 liters (8 to 10^/1000 gallons).
If chemical clarification must follow biological treatment, 200 to 400
mg/1 alum and no coagulant aid may be used. Color removals of about 95
percent can be expected.
The use of a polyelectrolyte has been found to be a useful aid to alum
dewatering in other work (VII 5.50).
Milco Industries of Bloomsbury, Pa., report successful color removal of
a closed dye cycle water using a combination of alum treatment, diatom-
aceous earth filtration and carbon adsorption.
-------
DRAFT
REFERENCES
7.1 "Standard Methods for -the Analyses of Water and^Wastewater11
—13th Ed., Water Pollution Control Federation.
7.2 "Methods for Chemical Analysis of Water and wastewater" Environ-
mental Protection Agency Report 1602, 07/71, 1971.
7.3 Federal Register. Vol. 38, No. 82, pp. 10642-10643, Monday
April 30, 1973.
7.4 Ford, D.L., "Public Works," April 1968, pp.89-92.
7.5 Ford, D.L., "Application of Total Carbon Analyzed for
Industrial Wastewater Evaluation," 23rd Industrial Waste
water Evaluation," 23rd Industrial Waste Conference, Purdue
University, 1968.
7.6 Jones, R.H., "TOC: How Valid Is It?" Water and Waste
Engineering, April 1972, pp. 32-33.
7.7 Davis, E.M., "BOD vs COD, vs TOC, vs TOD," Water and Waste
Engineering, February 1971, pp. 32-38.
7.8 Masselli, J., Masselli, M. t and Buford, M., "BOD? COD? TOD?
TOC?" Textile Industry, September 1972, p. 53.
7.9 Baines, F.C., "The Textile Industry and the Environment,"
AATCC Symposium, Washington, D.C., May 22, 1973.
7.10 Rudolfs, W., "Review of Literature on Toxic Materials
Affecting sewage Treatment Processes, Streams, and BOD
Determinations," Sewage and Industrial Wastes, 22, No. 9,
1157-1191, 1950.
7.11 Lamb, A., and Tullefson, E.L., "Toxic Effects of Cupric,
Chromate and Chromic ion on Biological Oxidation," Water
Research, Vol. 7, pp. 599-613, 1973.
7.12 Barth, E.B., et. al., "Summary Report on the Effects of
Metals on the Biological Treatment Processes," Journal
WPCF, 37, 1, 86-96, 1965.
7.13 "Water Quality Criteria," Second Edition by McKee 6 Wolf,
1963, by the California State Water Resources Control Board.
150
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DRAFT
7.14 Textile Chemist and Colorist, 5, ff pp. 10, 1973.
7.15 Suiter, R.N., and shipman, A.J., "Market Update," AATCC
Symposium Papers, "Textile Solvent Technology—Update "73,"
American Association of Textile Chemists and colorists.
7.16 Willard, J.J., "Solvent Processing," AATCC Symposium,
"The Textile Industry and the Environment," 1973,
American Association of Textile Chemist and colorists.
7.17 Fielding, B.C., "Solvent Based Resin Finishing," Textile
Chemist and Colorist, 4, 11, 1972.
7.18 British Patent: 1,243,462, Bleacher's Association,
Limited (Stubbs and Whitlegg).
7.19 Bryan, C.E., and Harrison, P.S., "Degradation of Synthetic Warp
Sizes," Textile Chemist and Colorist, 5, 109, 1973.
7.20 Jones, W.C., "Solvent Size/Desize^" AATCC Symposium Papers,
"Textile Solvent Technology - Update "73," American
Association of Textile Chemists and colorists.
5.1 Newton, E.H., Birkett, J. D., and Ketteringham, J. M., "Survey of
Materials Behavior in Large Desalting Plants Around the World,"
Report to Office of Saline Water, U.S. Department of the
Interior, (1972).
5.2 Brun, P. L. T., "Engineering for Pure Water, Part 2: Freezing:
Mechanical Engineering, February, (1968).
5.3 Koretchko, J., Hajela, G., "Bench Scale Survey of the Vacuum
Freezing Ejector Absorption Process" Office of Saline Water
Research and Development Progress Report No. 744 (1971).
5.4 Kenneway, T., "Freeze Desalination," Chemical and Process Engin-
eering, Vol 52, No. 6 (June 1971).
5.5 Loeb, S., and S. Sourirajan, Adyan Chem Ser. 38, 117 (1963).
5.6 Prehn, W. L., Jr. and J. L. McCaugh, "Desalting Cost Calculating
Procedures", Research and Development Progress Report, no. 555
to the Office of Saline Water, (may 1970).
Eng. Chem., Fundamentals 4, 113 (1965).
151
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DRAFT
5.8 Channabasappa, K. C., Water - 1970, Chem. Eng. Symposium Series 67
(107) , 250 (1971) .
5.9 Goldsmith, R., Abcor corporation. Personal Communication 1973.
5.10 Amicon product brochure (1973), Amicon Corp., Lexington, Mass.
5.11 Schrantz, J., Industrjal Fini shing, (Hitchcock, Pub.), (1972).
5.12 Goldsmith, R. L., R. P. de Filippi. S. Hossain and R. S. Timmins,
"Industrial Ultrafiltration" Chapter 13, p. 267 in "Membrane
Processed in Industry and Biomedicine", M. Bier, Ed., Plenum
Press (1971) .
5.13 Stribley, R. C., "Practical Characteristics of Four Selective Mem-
brane Electrodialysis in Mild Products Processing," Dairy In-
dustries, September, (1971) .
5.14 "Appraisal of Granular Carbon Contacting," FWPCA, Dept, Int. AWTRL-XI,
May, 1969.
5.15 "Optimization of the Regeneration Procedure for Granular Activated
Carbon," Water Pollution Control Research Series 17020,DAO
July, 1970.
5.16 Berg, Edward L., et al, "Thermal Regeneration of Spent Powdered
Carbon Using Fluidized-Bed and Transport Reactors," Chem.
Eng. Prog, Symp. Series, No. 107, Vol. 67, 1970.
5.17 Water Pollution Disposal and Reuse,Vol. I., Marcel Dekker, Inc.,
New York, 1971, p. 357.
5.18 Gould, Matthew and James Taylor, "Makeshift Granular Carbon System
Resolves Phenol Lagoon Pollution Threat," Chem. Eng. Prog. Symp.
Series, "Water" 65 (97) 196, 1969.
5.19 "Summary Report: Advanced Waste Treatment," FWPCA, Dept. Int.,
AWTR-19 (1968) .
5.20 "Current Status of Advanced Waste Treatment Processes." July 1,
1970. FWPCA, Dept. Int., PPB 1101.
5.21 O'Farrell, Thomas P., et al, "Advanced Waste Treatment at Washington,
152
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DRAFT
D.C." Chem. Eng. Prog. Symp. Series, No. 97, Vol. 65, 1969.
ditioning Food Processing Units with Activated Carbon," Chem.
Eng. Prog. Symp. Series, No. 107, Vol. 67, 1970.
5.23 Sebastian, Frank, P., "Tahoe and Windhoek; Promise andr-Proof of
Clean Water." Chem. Eng. Prog. Symp. Series, No. 107, Vol. 67,
(1970) .
Industries, March 1971.
5.25 Rodman, C. A., and Shunney, E. L., "Clean^Clear Effluent", Tex.
Manufacturer, 99. 49, pp. 53-56, (Apr. 1972).
5.26 Alspaugh, T. A., "Treating Dye Wastewaters." 45th Annual Conference
of the Water Pollution Control Federation, (1972)
5.27 Shunney, E.L., et al., "Decolorization of Carpet Yarn Dye Waste-
water." Am. Dvestuff Reprt.60: 6 (1971).
5.28 "Zeroing in on Five Top Trouble Spots." Textile world; U5 (Oct.
1971).
5.29 Heckroth, C.W., "A Challenge: How to Treat a Staggering Pollution
Load." Water & Wastes Eng. 8: 1, A-10 (1971).
5.30 Rodman, C. A., and Shunney, E.L., "Novel Approach Removes Color
from Textile Dyeing Wastes." Water & Wastes Eng.8; 9 (1971).
5.31 Northup, H. J., "There are Some Answers to Textile Pollution."
Textile Chem. & Colorist 2: 255-261 (July 29, 1970).
5.32 AATCC Symposium, Atlanta, Ga., April 1971 (and Supplement to Sympo-
sium Proc.).
5.33 Helfferich. F., "Ion Exchange"* McGraw Hill Book Co., Inc., New
York, 1962.
5.34 Kunin, R., and D. G. Downing, Water 1970, Chem. Eng. Symposium
Series 67 (107) , 575 (1971) .
5.35 Abrams, I. M., Ind. Water Eng., Jan/Feb, (1973).
5.36 National Canners Association, "Reduction of Salt Content of Food
Processing Liquid Waste Effluent", EPA Project #12060DXL,
Water Pollution Control Research Series, (January 1971).
153
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DRAFT
5.37 Souther, R. H., and Alspaugh, T. A., "Textile Waste Treatment Studies,
Proc. Purdue Ind. Wastes Conf. 13: 662 (1958).
5.38 Souther, R. H., and Alspaugh, T. A., "Treatment of Mixtures of Tex-
tile Waste and Domestic Sewage.: Am. Dvestuff Reptr. 47:
480 (1958) .
5.39 Geyer, J. C., "Textile Waste Treatment and REcovery." The Textile
Foundation, Washington, D.C. (1936).
5.40 Lawton, E., "Textile Mill Effluent control," Textile Forum: 8
(Feb. 1965) .
5.41 Lumb, C., "Pollution by Textile Effluents in the Mersey Basin."
Shirley Inst. Pamp. No. 92, 1966.
5.42 Little, A. H., "The Treatment and Control of Bleaching and Dyeing
Wastes." Water Poll. Control 68, No. 2: 178 (1969.).
5.43 Ryder, Lincoln W., "The Design and construction of the Treatment
Plant for Wool Scouring and Dyeing Wastes at Manufacturing
Plant, Glasgow, Virginia." J. Boston Soc. Civil Engrs. 37,
183-203 (April 1950).
5.44 Sadow, Ronald, D., "The Treatment of ZefranR Fiber Wastes."
Proc. 15th Ind. Waste Conf., Purdue Univ., Ext. Ser 106, 1961.
5.45 Davis, Charles, L. Jr., "Lime Precipitation for Color Removal in
Tertiary Treatment of Kraft Mill Effluent at the Interstate
Paper Corporation, Receboro, Georgia," Chem. Eng. Prog. Symp.
Series, no. 107, Vol. 67, 1970.
5.46 "OPD's Mechanical-Chemical System Kills Foam in the Bluestron."
Textile World; 61 (Nov. 1967).
5.47 Mytelka, S. W., and Hutto, G.A., "Treatment of TExtile Mill Waste
in Aerated Lagoons," Proc. Purdue Ind. Wastes Conf. 16:
518 (1964).
5.48 Rodman, C. A., and Shunney, E. L., "New Concept for the Biological
Treatment of TExtile Finishing Wastes," Chem. Eng. Prog.
Symp. Ser. 67: 107 (1971).
5.49 Stewart, R. G., "Pollution and the Wool Industry", Wool RBsearch
154
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DRAFT
Organization of N.Z. (Inc.), No. 10, Sept., 1971.
5.50 King, P. H., and Randall, C. W. , "Chemical-Biological Treatment
of Textile Finishing Wastes," 19th So. Water Res. & Poll.
Control conf. (Duke), April 1970.
155
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DRAFT
SECTION VIII
Cost, Energy, and Nonwater Quality Aspects
BEST PRACTICABLE TREATMENT TECHNOLOGY (Level I)
This chapter summarized the costs (necessarily generalized) and
effectiveness of end-of-pipe treatment systems either currently in use
or recommended for future use in the textile industry. More detailed
analyses for industry categories have been presented in Supplement A of
this report. In order to reflect the very different treatment economics
between existing and new plants or between small and large ones, costs
have been developed in Supplement A for, typically, two plant sizes in
each industry category. The purpose of this discussion is to describe
the basic cost analyses upon which the product-specific estimates are
based.
Supplement A also includes updated inputs for EPA's Industrial Waste
Treatment Model. The estimated total volume of wastewaters discharged
for industry categories has been provided for 1972 and 1977. Also,
general estimates of the current level of treatment in different indus-
try segments have been made.
The best practicable treatment technology in this industry is considered
as the end-of-pipe treatment steps shown in Figure VIII-1.
Primary Treatment; For removal of suspended solids. Includes
equalization, screening and chemical coagulation or precipita-
tion (to remove heavy metals where required),
Secondary Treatment: Primarily for removal of BODS. Includes
aerated stabilization basins, sludge recycle and disposal, and
final clarification with a long-duration polishing lagoon.
(Land and land-fill requirements are very small.)
Information on actual treatment cost experience in the textile industry
was available in varying degrees of completeness from the exemplary
plants visited. To verify the quality of the data received and to
provide a broader basis for estimation, a costing model was developed
based on standard wastewater treatment practice. This model covers both
capital and operating costs for the equivalent of what appears to be the
best technology currently practiced by the industry: essentially
primary and secondary treatment as extended aeration with stabilization
ponds. Over a plant size range of 400-12,000 cubic meters per day (0.1
156
-------
Raw Wastewater
Primary Screening
Aeration
Stabilization
Basin
Clarifier
u
a>
QC
o>
o>
T>
J3
to
Three-Day
No n-Aerated
Lagoon
Final Discharge
FIGURE VIII-1 SCHEMATIC FLOW
DIAGRAM OF PROCESS STEPS AND COST
CENTERS FOR LEVEL I TREATMENT
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DRAFT
•to 3.0), -the cost experience data from the plants visited came within 30
percent of that predicted by the cost model, as shown by the examples in
Table VIII-1. The costs calculated from the model, therefore, are
believed to be realistic bases for estimating the (replacemfent) value
of existing facilities and the economic impact of further secondary-type
treatment requirements.
Cost curves developed from the cost model are presented in Figures VTII-
2 to VIII-10. (For very small plants (about 110 cu m/day or 30,000
15ft
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DRAFT
Table VIII-1
AccuracY^of Standardized Costing Methodology
Example Plant
Plant A (0.394 mgd)
Category 1
Aeration basin
Aeration equipment
Clarifier
3 day lagoon
yard work (15X const)
engineering
Plant Q (2.5 mm gal/day)
Category 4
Aeration
Aeration equipment
Clarifier
3 day lagoon
yard work (15X const)
engineering
Plant X (1.7 mm gal/day)
Category 5
Aeration basin
Aeration equipment
Clarifier
3 day lagoon
yard work (15X const)
engineering
ADL std
cost estimate
Company reported
cost for actual plant
Ratio
ADL
reported
refined
$ 27,000
136,900
35,600
12,500
$212,000
31,800
42,400
$286,200
$ 59,000
123,400
116,400
3.200
$330,800b
49,600
60.000
$440,400
$ 57,000
23,600
98,800
27.000
$206,400
31,000
47.000
$284,400
$210,000
1.36
$554,000
0.79
$335,400
.85
[Land cost left off these estimates in order to compare with plant reported
-------
DRAFT
cost — maximum land cost, plant Q, is $6000. ]
166
-------
DRAFT
1,000,000
o
Q
S 100,000
8
10,000
10.0
FIGURE VIII-2 AERATED STABILIZATION BASIN
CONSTRUCTION COST
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DRAFT
10,000
_ 1,000
I
UJ
100
10
100
1,000 10,000
Total Construction Cost, ($000)
100,000
FIGURE VI11-3 ENGINEERING COSTS
-------
DRAFT
I
o
Q
I
lOx
105
1x103
I 1 i i i 11
I I I I I i
ENR Index--1811.93,
Jan. 1973
i I I i 11
1.0 10.0 100.0
Flow, mgd
FIGURE VIII-4 CLARIFIER CAPITAL COST
-------
DRAFT
10x105
1.0x10
1.000
ENR Index = 1811.93, Jan. 1973
II i
10,000
BOD removal, Ib/day
100,000
FIGURE VI11-5 AERATED STABILIZATION BASIN
(Aeration Equipment Only)
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DRAFT
10,000
o
£
C
n
1 1,000
100
Operation
Maintenance
i i t i t i i i
1.0
10.0
Flow, mgd
100.0
FIGURE VIII-6 AERATED STABILIZATION BASIN
ANNUAL OPERATION AND MAINTENANCE LABOR
-------
DRAFT
10,000
o
o
8 1,000
"co
3
c
c
100
Chemicals for 'Typical" Plants
ENR = 1811.93, Jan. 1973
Material &
Supply Costs
_i I
1.0
10.0
Flow, mgd
I i
100.0
FIGURE VIII-7 AERATED STABILIZATION BASIN
1. Material and Supply Com, Annually
2. Chemical Cost*
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DRAFT
100,000
o
o
o 10,000
D
c
1,000
1,000
I I I
t I
I I I I I
10,000
BOD removal, Ib/day
100,000
FIGURE VI11-8 AERATION EQUIPMENT
ANNUAL POWER COSTS
Aerated Stabilization Basin
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DRAFT
10,000
D
o
± 1,000
3
c
100
1.0
Operation
Maintenance
Jiii
10.0
Flow, mgd
100.0
FIGURE VIII-9 CLARIFIER, ANNUAL OPERATION AND MAINTENANCE LABOR
-------
DRAFT
100.000
o
a
S 10,000
1,000
Material and Supply Costs
10.0
F low, mgd
100.0
FIGURE VIII-10 CLARIFIER
1. Material and Supply Costs, Annually
2. Major Chemical Costs
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DRAFT
an overall cost figure of $264 for 1 cu m/day or $1.00 for 1 gpd was
assumed.) Figures VIII-6 to VIII-10 present the operating and main-
tenance costs over the ranges of production found. The initial capital
cost of biological treatment systems depends mainly upon (and here is
related to) the hydraulic load, the other factors making only minor
variations in the total cost. Operating costs, on the other hand, have
been viewed as dependent on pollutant as well as hydraulic loads.
Costs for representative large plants in industry categories were
developed using these curves and assuming an aerated stabilization
basin, which is widely used by the industry when land is readily avail-
able. The following items were determined for the individual treatment
steps:
(1) Construction cost as a function of hydraulic load at a given
pollutant level;
(2) Operating and maintenance labor as a function of hydraulic
load;
(3) Chemical requirements as a function of hydraulic and pollutant
load;
(4) Power requirements as a function of hydraulic and pollutant
load;
(5) Additional material and supply cost as a function of hydraulic
load.
The cost data used were derived from varied industrial and municipal
applications. They are adjusted where possible to reflect specific
changes necessary for the textile industry. Costs have been adjusted to
a national average cost level of January 1973 using the ENR Construction
Cost Index. The estimated cost curves have been adjusted to exclude
unusual construction or site-specific requirements. The curves include
all elements of construction cost which a contract bidder would normally
encounter in completing the wastewater treatment. Included are building
materials, labor, equipment, electrical, heating and ventilation, normal
excavation and other similar items. Also included are the engineering
costs. The annual operating costs include operation and maintenance
labor, chemicals, power, material and supplies, and depreciation.
BEST AVAILABLE TREATMENT TECHNOLOGY (LEVEL II)
Zero Discharge
170
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DRAFT
From a consideration of the data on advanced treatment technology given
in Chapter VII, reverse osmosis or evaporation followed by incineration
appears to show the most promise for achieving zero discharge. The flow
diagram for a zero discharge system is shown in Figure VIII-11,
We have carried out detailed costing of this technology for two categor-
ies in the textile industry—H, Woven Fabric Finishing, and 5, Knit Fa-
bric Finishing—because these two segments contributed the major waste
loads in the industry. To compute the total costs, we have assumed
water economy and reuse within the process, and for Category 4 show some
of the ways this might be achieved.
The continuous wet processing of woven 100 percent cotton cloth is
carried out in a series of baths, saturators, and/or holding devices.
The unit operations making up the over-all process vary from plant-to-
plant and line-to-line and depend on the product and on individual
company preferences. It is, therefore, impossible to pick a standard
process that characterizes the industry, and also provides an example of
exemplary operations.
After review of the literature, field interviews and discussions amongst
consultants and industry experts, the process, as outlined in Figure
VIII-12, was decided on as the most extensive representative that may be
encountered for category U. This processing consists of taking 100
kg/1000 kg of PVA sized greige goods through water desizing, caustic
scouring, two stages of peroxide bleaching, followed by mercerizing and
dyeing.
At the given production rate, the water balance for this series of unit
operation shows 2020 gpm of water going to the sewer or a discharge of
22.3 gallons of water per pound of cloth produced.
The present state of technology, as represented by Figure VIII-12, shows
the complex nature of wet processing being practiced today. In attempt-
ing to reach a water usage for Level II application, a two-step recycle
approach is hypotehsized. The first step is represented by Figure VIII-
13. To reduce the water consumption counter-current processing was
imposed on the process as follows. The wash effluent from the second
stage peroxide bleaching is introduced as wash water to the first stage,
and effluent from this wash is used one step further back in the
scouring wash. Because of the nature of the process, this is probably
the extent to which counter-current processing can be utilized.
However, there is no apparent reason why the desizing waste stream,
which consists of PVA and/or PVA-starch blends cannot be introduced as a
171
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DRAFT
Raw Wastewater
Primary Screening
Aeration
Stabilization
Basin
Condensate
Water Returned
to Process
(Or Reverse Osmosis Unit)
Solids to
Land Fill
VIII-11 SCHEMATIC FLOW DIAGRAM OF
PROCESS STEPS AND COST CENTERS FOR
ZERO DISCHARGE TREATMENT
I7Z
-------
DRAFT
first-stage scouring wash, as shovm in Figure VIII-13. The dilution
factor in the wash stream from desizing should minimize the problems of
starch-caustic reactions in this processing step. Also, the
concentrations of caustic (20X) used in mercerizing should allow for
evaporation and reuse.
The second step is shown in Figure VIII-14. The major difference rep
173
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DRAFT
SCOUR
100 Ib/min
Cotton
Greige goods
BLEACHING
145. 3 Ib/min
Greige goods
<°> 42.9% Moisture
MERCERIZING
144.7 Ib/min
Cotton
<3> 42.8% Moisture
Stream A
\
Desize
I
Stream B
to Sewer
Stream F
I
Peroxide
Bleach
Saturator
Stream 1
t
Mercerize
1
Stream K
to Sewer
Stream C Steam Stream D
i 1 1
Caustic Recuperator
^ S-"!"'"' ,„*. MWH , ». Wash t
\
Stream E
to Sewer
Stream G Stream F Stream G
\ 1 J
1
Peroxide :
J-Box Wash B|en h ^ J-Box Wash fc
Saturator
i
I
Steam ' Steam
Stream H Stream H
to Sewer to Sewer
., „ >, DYEING
H2O Vapor
Stream J
1 J
86.9 Ib/min 90.5 Ib/min
Cotton Cotton @ 6% Moisture
@ 6% Moisture
1
Stream L
to Sewer
FIGURE VIII-12 1000% COTTON-ROPE
CONTINUOUS WET PROCESSING (present
practice)
-------
DRAFT
SCOUR
100 Ib/min
Greige goods
5% Moisture
Stream A
I
Dasize
Stream C
Scour 1
Caustic
Saturator
Steam
I
Recuperator
(190°F)
Reci
Stre
fc\e
jm
1
^— Stream B /
-•— Stream M
•»— Stream?
Wash
Stream B
to Scour Wash
Recycle
Stream N
to Sewer
1st Stage
Stream M
to Scour Wash
Recycle
2nd Stage Stream H to-J
Str
1st Stage Bleach
BLEACHING Recycle
Stream F Steam Stream H Stream F Steam Stream G
\ J 1 i , »
Peroxide
Bleach
Saturator
J-Box
Wash
Peroxide
Satuntor
J-Box
Wash
MERCERIZING DYEING
H
in ,
H2<3 Vapor
i Stream J
_t J~
^
20% NaOH
R ecycle
Mercerize
\
i >
90.5 Ib/min
Cotton @ 6% Moisture
» Stream 0 to '
Scour Wash Recycle Stream L
to Sewer
4 | Evaporators | « (Settling W
1
To Process 1
—•*• Solids to Landfill
FIGURE VIII-13 100% COTTON-ROPE
CONTINUOUS WET PROCESSING (1st pass
recycle)
-------
DRAFT
SCOUR
100 Ib/min
Greige goods
5% Moisture
BLEACHING
MERCERIZING
20%NaOr
Recycle
•^0
•{ Evaporators (•*-
> Process
Stream R
I
Deiize
Stream S
Wash Recycle
Stream F
I
Peroxide
Saturator
1st Stage
Mercerize
1 1
1
— | Settling|*-
Recycle f"" StreamS
Stream "• Stream Q
Stream C Steam •« Stream 0
I 1 _g Stream W
i T _::
Caustic Recuperator
t
Stream T
to Sewer
Steam Stream H Stream F Steam Stream G
11 I I \
1
Peroxide
J-Box ^ Wash „,„ u _ J-Box _ Wash _
Saturator
b Stream R to Desize 2"d Sta96 Stream H to "*— '
Stream Q to Scour 1st Stage Bleach
Wash
., _ .. DYEING
H2°Vapor Stream U
t 1
90.5 Ib/min
Cotton
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DRAFT
This page left intentionally blank.
177
-------
DRAFT
resented in this f-.^ure is the use of full counter-flow washing in each
process step. As a result, water consumption for the outlined process
is projected at 805 gpm or 8.9 gallons per pound of cloth produced.
Further in-process recycling of water shows diminishing returns,
therefore, the next logical step is treatment of the wash stream to
provide zero discharge of water pollutants. Although it might be
possible to treat waste streams from the individual process steps,
because of scale of operations and lack of proven technology, only the
cost of treating the final effluent can be realistically estimated.*
Two processes were evaluated as the most applicable for reaching zero
discharge: (1) multi-stage flash evaporation followed by incineration;
and (2) reverse osmosis followed by incineration. Evaporation
represents proven technology and reverse osmosis unproven technology in
this industry. Tables VIII-2 through VIII-5 show the cost calculations
as applied to these to treat the waste streams for the outlined process.
The information as summarized in Table VIII-2 shows that the cost of
evaporation varies from $0.77 to $0.9U/1000 liters ($2.90 to $3.56/1000
gallons) and for reverse osmosis from $0.91 to $1.06/1000 liters ($3.56
to $1.02/1000 gallons), as concentration increases and flow rate
decreases. With a credit of 1*/1000 liters (15*/1000 gallons) , assuming
that the water can be recycled to the process, these costs reduce to
$0.76 to $0.93/1000 liters ($2.88 to $3.51/1000 gallons) for evaporation
and $0.93 to $1.05/ 1000 liters ($3.51 to $1.00/1000 gallons) for
reverse osmosis. Economic differences between the two processes appear
to be small and within the error of estimation.
The wet processing of nylon and/or acetate knit goods normally consists
of dyeing with dispersed systems, followed by treating with resins for
shrinkage resistance, usually in a batch system. A unique feature of
178
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DRAFT
TABLE VIII-2 "ZERO" DISCHARGE COSTS 100% COTTON - ROPE
.st Pass Reccle
2nd Pass Recycle
Solids (TDS) ...
Total Cap. Employed
Annual Oper. Cost
Indirect Oper. Cost
Total costs/Year
$/day
$/1000 gallons
. . (1. 87 MG;
• •
Multi-Flash
Evaporation
$ 4,232,000
1,151,000
825,300
1,976,300
5,414
2
(figure VIII-22) (figure VIII-23)
D, 14.4 gal/lb) (1.16 MGD, 8.9 gal/lb)
N 2000 mg/1 N 4000 mg/1
Reverse
Osmosis
$3,427,000
1,759.900
668,300
2,428,200
.52 6,652.
.90 3.
Multi-Flash
Evaporation
$3,151,000
892,700
614,500
1,507,200
60 4,129.32
56 3.56
Reverse
Osmosis
$2,323,000
1,249,000
453,000
1,702,000
4,663
4
.01
.02
Secondary Treatment Cost
3 $/1000 gallons
credit for Water Saved
9 $15/1000 gallons
Net Final Cost
S/1000 liters
S/1000 gallons
Net Final Cost
0/kg of cloth
of cloth
.13
.15
.13
.15
.13
.15
.76
2.88
9.1
4.1
.93
3.54
11.2
5.1
.93
3.54
6.9
3.2
.13
.15
1.05
4.00
7.8
3.6
179
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DRAFT
TABLES VIII-3 FLOW AND SOLID CALCULATIONS
1st Pass Recycle (figure VIII-22)
Water to sewer:
Flow - 1300.1 gpm or 1.87 MGD
Solids - 34.45 Ib/min or 49608 Ib/day
34.45 Ib/min 453.6 mcr/lb 10000 mg/gm =
1300.1 gpm 3.79 liter/gal
3171 ing/liter Total Solids.
3171 mg/liter X 26.5 Ib/dissolved solids =
34.45 Ib/total solids
2434 mg/1 dissolved solids.
Therefore use 2000 mg/1.
2nd Pass Recycle(figure yyiI-23)
Water to Sewer:
Flow - 805 gpm or 1.16 MGD
Solids - 34.45 Ib/min
Concentration is 3834.2 mg/1 Dissolved Solids or
approx. 4000 mg/1
180
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DRAFT
TABLE VIII-4 MULTI-STAGE FLASH INCINERATION
1st.Pass Recycling 2nd Pass Recycling
(1.87 MGD) (1.16 MGD)
2000 Mg/1 TDS 4000 Mg/1 TDS
Capita1Employed
Multi-stage Evap. $2,850,000 $1,950,000
Crystallization 270,000 270,000
Land fill 240,000 240.000
$3,360,000 $2,460,000
Engineering 320,000 280,000
Contingency (15% of above) 552.000 411.000
Total Capital Employed $4,232,000 $3,151,000
Annual Oper. Costs
Labor Oper. $5/hr x 19500 hr 97,500 97,500
Main. $5.5/hr x 6400 hr 35,200 35,200
Fringe (25X) 33.200 33.200
Total Labor $ 165,900 $ 165,900
Electric Power 143,800 89,200
Fuel 551,500 403,100
Solids Disposal 92,500 92,500
Maintenance Mat. (4%) 169,300 126,000
Chemical & Oper. Suppl. 28,000 16.000
Total Oper. Costs $1,151,000 $ 892,700
Indirect Oper. Costs
Taxes & Ins. (9 1 1/2% cap) 63,500 47,300
Cost of Capital (9 8%) 338,600 252,400
Depreciation (9 10%) 423,300 315.400
Total Costs $1,976,300 $ 614,500
$/day 5,414.52 4,129.32
$0.77/1000 liters $0.94/1000 liters
($2.90/1000 gal) ($3.56/1000 gal)
181
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DRAFT
TABLE VTII-5
INCINERATION
REVERSE OSMOSIS, EVAPORATION
Reverse Osmosis Evaporator-Crystallizer
Capital Employes
Reverse Osmosis
Crystallizer
Land Fill
Engineering
Contingency (1555 of above)
Total Capital Employed
AnnualOper._Costs
Labor: Oper. $5/hr 12,000
Main. $5.5/hr 5,000
Fringes 25%
Total Labor
1st Pass Recycle
(1.87 MGD)
2000 Mg/1 TDS
$1,900,000
560,000
240.000
2,700,000
280,000
447.000
$3,427,000
60,000 7200
27,500 3100
21.900
$ 109,400
Electric Power 1405 kwh/dy/ 1,136,400
mgd
Fuel
Solids Disposal
Maint, Mat. & Supply (1 1/2X)
Chemical & Membranes
Total Oper.
Indirect OPer. Cost
Taxes 5 Insur.~(l 1/2X)
Cost of Capital (8X)
Deprec. (10%)
Total Costs
$/day
180,200
92,500
51,400
190.000
$1,759,900
51,400
274,200
342.700
$2,428,200
6,652.60
$0.94/1000 liters
($3.56/1000 gal)
2nd Pass Recycle
(1.10 MGD)
4000 Mg/1 TDS
$1,020,000
560,000
240.000
1,820,000
200,000
303.000
$2,323,000
36,000
17,100
13,300
$ 66,400
705,000
220,168
92,500
34,900
130.000
$1,249,000
34,900
185,800
232.300
$1,702,000
4,663.01
$1.06/1000 liters
($4.02/1000 gal)
182
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DRAFT
dispersed dye-* is thr.t they do not require the use of salts in the
dyeing The high use of soluble salts in dye plants is a principal factor
militating against extensive re-use of process water in the textile
industry. The two knit mills considered here do not utilize salt to any
great extent in their dyeing and indeed this is a fundamental reason
these are among the first types of plants to consider recycling dye
waters.
In our examination of this segment of the knit industry we focused on
two exemplary mills, one making nylon acetate lingerie and one making
nylon hosiery. The water usage for dyeing in the lingerie plant is 25-
33 I/kg (3 to H gal/lb) of cloth and in the panty hose mill (8.1 gal/lb)
68 I/kg of cloth.
Process flow sheets for the two plants are shown in Figures VIII-15 and
183
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DRAFT
VIII-16. i-nese flc^ sheets show the sources of the waste stream and the
total flow from the dye house to the sewer or treatment plant.
Figure VIII-»7 is based on a water treatment system that is in start-up
phases at Plant HH. This system is designed to treat dispersed dye
wastes and is applicable to similar wastes in considering Level II
guidelines. The process, as described, flocculates, filters, and de-
ionizes the water, removing enough impurities to allow for recycling.
The only liquid waste system from the process is the de-ionizer
regeneration stream. This amounts to 23 to 32 kilograms (50 to 70
pounds) of salts (Mg and Ca) dissolved in 10200 liters (2700 gallons) of
H20 every two days, which is currently discharged to municipal treatment
plants. For zero discharge, these salts could be disposed of via an
evaporative type process.
The estimated costs of treating the wastes, via the process outlined in
Figure VIII-26 for zero discharge are shown in Table VIII-6. Treatment
costs are approximately $0.42/1000 liters ($1.60/1000 gal) or $0.02/kg
($0.01/lb) of product, including evaporation of de-ionizer regenerative
waste. After taking credit for the recycled water the net cost comes to
$0.38/1000 liters ($1.J»5/1000 gal).
-------
DRAFT
Soap
Scour
36.000 dozen/day from knitting
(21,600lb/day)
\
Water »»
Rinsi
i
I
i
Dispersed
Dyes |»
Surfactant
Water ».
Lanolin ^
Softners
Dye
I
I
r
Rinse
i
i
,
r
Finish
\
ToDr
Paka
»_ Water
Soap
Knitting Oils
^ Water
Dye
Surfactant
Wastage
X
/ing &
ging
175.000ga./day^ JnM^r
8.1 gal/lb Treatment Plant
FIGURE VIII-15 WOMENS1 NYLON PANTY
HOISERY BATCH
-------
HjO Surfactant
50,000
Ibs/day
Batching
H2O Disperse and
Acid Dyes
Surfactant Phosphates
Urea
Finishing
T
Minor Urea to Sewer
H20
Dye Wastes
Surfactant
Vacuum Extraction
200 gal/hr to atmosphere
H2 O and Wastes to Sewer
\
\/
150 to 200,000 gal/day
(3 to 4 gal/1000 Ib of Cloth)
To Sewer or Treatment
L
C
FIGURE VIII-16
GOODS BATCH
NYLON/ACETATE KNIT
-------
Waste From Dye House
150,000-200,000 gal/day
(3.5 gal/lb of
Production)
1,000 ppm Total Solids
250 ppm Suspended
Solids
Collection
Tank
Caustic
._ Alum
i— Activated Carbon
i— Polyelectrolyte
_ Activated Carbon
Diatomaceous Earth
Sulfonic Acid
Sludge
Lines
Sludge
Thickening
T
Water Return Line
Sludge To Landspill
(50% of Solids Input)
(Approx. 725 Ib (Dry)/day)
(7975 Ib Wet)
t
Recycle to Dye House
(Approx) 180,000 gal/day
Cfe
_L
Salt Regeneration
Avg.90lb/2700galH2O
-i I Use Cases
Y I Two Days
Deionizers
J
Return
Tank
Regeneration Waste To Evaporatk
50 to 70 Ib of Various Mg + Ca
Salts in 2700 gal H,O
Air
LI
Add Fresh Water
Make-up — Approx 2500 gal/day
O
FIGURE VIII-17 NYLON/ACETATE KNIT
WATER TREATMENT PLANT DISPERSED OR
ACID DYES
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DRAFT
TABLE VIII-6
ESTIMATED COSTS OF WATER TREATMENT (ZERO
DISCHARGE) FOR NYLON/ACETATE KNIT GOODS*
Capital Employed
Treatment Plant (including Eng., etc) $ 120,000
Evaporator (De-ionizer Regeneration Wash) 25.000
$145,000
Annual Oper. Costs,
Chemical $10,000 - 15,000
Labor (includingffringe) 30,000
Maintenance & Related (5% of capital) 7,250
Steam & Power 3,300
Make up Water ($.20/1000 gal, 25,000 gpd) 1.500
Total Oper. Costs $57,050
Indirect Oper. jCosts
Taxes 5 Insurance (1 1/2X of Cap.) 2,180
Cost of Capital (8 10%) 14,500
Depreciation (3 7%) 10.150
Total Indirect costs $26,830
Total Costs $83,880
$/day 293.29
$/1000 liters 0.42
$/1000 gallons 1.60
Credit for recycled water 9 15*/1000 gal 0.15
Net water cost 1.4 5/100 CV
0.38/1000 1
*Basis: Plant described in Figure VIII-26
Ref: Plant HH and ADL Estimates
188
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DRAFT
SECTION IX - Best Practicable Control
technology Currently Available
INTRODUCTION
The best practicable control technology currently available has been
found to be comparable to the primary and secondary treatment of
municipal sewage.
Level I guidelines are based essentially on well-operated activated
sludge plants or extended aeration lagoons, along with chemical
separation of heavy metals in some of the industry categories. The not-
to-exceed guidelines that are recommended will require 93 percent or
more BOD removal in four of the six categories that have significant
pollution.
This technology has proved to be applicable regardless of the age or
size of the plant. It is capable of reducing concentrations of oxygen
demanding substances in the effluent stream to reasonable limits,
depending upon the treatability of the wastes. However, variations due
to the vagaries of the microorganisms as well as process and climatic
conditions are normal for any well-designed biological waste water
treatment plant.
An activated sludge system which is permitted to operate at a constant
F:M ratio all year round and with minimum operational changes would have
a natural variation as shown by the solid line in Figure IX-1.
A similar system with careful operational control would have a
controlled monthly average variation as shown by the points. Although
the mean value is the same, the amount of natural variation is
controlled by the operator through aeration rate control, sludge
recycling and F:M ratio adjustments. These adjustments can be made
daily so that monthly averages can be held within the desired limits.
Although a well-operated facility (properly designed) can be controlled
within +25 percent of the average on a monthly operating basis, an
allowance of SOX deviation from the average will be used to calculate
the maximum monthly effluent limitation.
The results of this work show that exemplary waste water treatment
plants are presently in operation, that their operations are compatible
with widely accepted and achievable operational guidelines for
biologically-active substances, and that the most significant factors in
establishing guidelines and limitations are the pollutants unique to the
manufacturing processes.
189
,,..,. - •. . .-0 ••;.;;j v;- rrc...:vor..a'. ens '..a.ci u/cn inlcriv.aton in this
n°port and are lubjest to efcnc* tzsed upon comments rccc.ved and further
review by EPA.
-------
*. a
40
36
32
o
8 24
O
LU
LU
20
12
4
TYPICAL SEASONAL VARIATION
FOR ACTIVATED SLUDGE
SEASONAL VARIATION
WITHOUT CONTROL
1 ?
£ -4>
D
ITROLLED OPERATION -C
IMUM OPERATIONAL CHANGE #
M A M J
MONTH
N
D
FIGURE IX-1
-------
DRAFT
EPA and the textile industry desire to simplify the approach to Federal
pollution abatement guidelines by using simple subcategories within the
industry. It should be understood that decreasing the number of
categories makes each less homogeneous and therefore more susceptible to
larger variations in waste effluent. Moreover, as discussed in Chapter
IV, no simple means of subcategorizing the industry further to take into
account varying loads have been found.
These concerns are particularly valid for categories 2 and 7, wool
finishing, and stock and yarn dyeing respectively, both of which are on
the lower end of the treatability scale (90 percent BOD removal) and
categories 1 and 4, wool scouring and broad woven finish, both of which
have high raw waste loads.
191
I'OTri- Heis ao ;er.;a..vo re:oni~onjal.cns t-.a-oJ upon information in this
report anJ are subject lo clianje based upon comments received and further
review by EPA.
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DRAFT
CONTROL TECHNOLOGY
The engineering aspects of applying best practicable technology are well
understood once the treatability of waste water streams has been
established. This treatability can be tested on a laboratory scale or
on a pilot plant scale. Scale-up of the test results by the application
of techniques widely-used throughout the waste water treatment industry
should be relatively straightforward. However, it must be recognized
that appropriate safety factors are required in designs and that short-
circuiting these factors in order to minimize capital investment may
mean the difference between a marginally-performing waste water
treatment plant and one performing at achievable efficiencies.
The availability of practicable technology for removal of biologically-
active substances means that reduction in the concentration of these
substances, as measured by BODjj tests, should be achievable within
acceptable limits. The cost of achievement and its impact will be a
function of the specific plant and its location.
Since biologically active substances in the waste waters have been shown
to be removable to degrees commensurate with well-known waste water
treatment technology, the development of industry guidelines and
limitations must focus on the specific conditions encountered at each
operating plant. As has been seen, the conditions depend upon a large
number of factors, the most important of which are the following:
1. The water usage rates at the plant. These may vary for a
number of reasons, some peculiar to the process, some dependent upon the
type and age of equipment, some dependent upon nonprocess practices or
requirements, and some upon the age and configuration of the plant.
2. The nature and amounts of pollutants generated per unit of
product. The pollutant load per unit of production for similar
processes at different locations or between different equipment will
vary because it is inherently impossible to control precisely all the
physical and chemical variables required to produce a highly-uniform
flow of waste water with relatively constant compositions.
3. Segregating and preventing pollutants from entering waste water
streams. The in-plant housekeeping practices and process designs that
prevent pollution by preventing or minimizing spills, drips and leaks
from equipment from entering the waste water system can affect both the
raw and treated waste loads.
192
NCPIC:: 7!:r : ••• '"-.••' • :-r r;- '""; '• *' -•• :l ::--'r:- •'•"c ' l!
review !)>• tl'A.
-------
DRAFT
H. The relationship between the pollutant-removal capabilities of
the end-of-prpe trea*v.nent systems and the pollutant levels applied,
especially as these may be affected by operational upsets, changes in
process operating conditions, or changes in plant production rates.
The limitations that these factors set upon establishing guidelines for
best practicable control technology are discussed below.
Biological Oxygen Demand
Using best practicable control technology currently available, industry
is capable of attaining and maintaining a BOD5 level in the effluent
within limits imposed usually by the characteristics of the biological
treatment system and not by the characteristics of the process. Since
it is necessary to consider concentration units, the effects of
unusually-high concentration of BOD5 in the influent to the waste water
treatment plant must be given due consideration.
Chemical Oxygen Demand
Measurements of chemical oxygen demand (COD) substituents in the waste
water by COD test, or measurement of organic carbon by the TOG test,
vary widely because of differences in organic chemical species as well
as the influence of oxygen demand by inorganic species. The measurement
of COD includes not only substances subject to biological oxidation, but
many substances not biologically oxidizable as well. The measured COD
content of the treated waste will be expected to vary more widely than
the BOD since little or none of the contributing species — which vary
in type and quantity with time — may be removed. Whereas, biological
oxygen demanding substances may be expected to be removed to similar
concentration levels in the treated effluent in spite of significant
influent variations, that portion of the incoming COD which is non-
degradable by biological means will result in the same concentration in
the effluent.
Suspended Solids
Gravity sedimentation is the best practicable control technology
currently available and is typical of biological waste water treatment
processes. The separation of suspended solids by gravity methods is
dependent on a number of important operational variables, such as the
•overflow rates in the sedimentation tanks, the nature of the
microorganisms, the effects of climatic conditions on settling lagoons,
the effects of temperature variations in the waste water flows, the
•presence of colloidal particulates from the process operations, and the
effectiveness of such sedimentation aids as polyelectrolytes or
193
NOTICE: Thcss c:o 'is-1: v •:•.:.-•.,: cr'.r :.i; ':;i ?. :..;•;.,- >'.,,- :;;;cn ;„ thjs
report and ate subject '.3 ci'crr.c Jaso: u. on csrr.r.cnli icjjvrj a.ij further
review by EPA.
-------
DRAFT
adsorptivc *locs. Ccher methods for separation of suspended solids are
available, such as dissolved air flotation or in-depth media filtration.
In general the problem of suspended solids removal in this industry is
analogous to that of municipal sewage treatment plants except for a
small number of unique considerations. The limitations of best
practicable control technology currently available for removal of
suspended solids are due to the nature of the colloidal substances
produced in the process or in the waste water treatment system where
soluble substances are converted into insoluble solids. Consequently,
variability in the concentration of suspended solids from a well-
designed and operated waste water treatment plant can be attributable to
both process and waste water treatment plant operations, and not
predominantly to one or the other, as in the case of BOD and COD. The
removal of suspended solids requires conscientious and capable operation
of well-designed waste water treatment plants operating within
practicable parameters.
Heavy Metals
Except for chromium used in dyeing and as a rust inhibitor in cooling
water systems, heavy metals are not a significant problem in the textile
industry. The removal of chromium from cooling system blowdown is a
well-established technology that is currently available from other
industries, equipment suppliers, or consultants.
Phenols
Phenolics generally are present in textile waste waters in
concentrations where biological treatment is the best practical control
technology. Activated carbon absorption has been used for removal from
both high concentration and low concentration wastes. The limits that
are proposed from this study are based on industry experience with
respect to effluent phenol concentrations achieved by activated sludge
plants, rather than on specific processes for removing phenols.
Color
The technologies for color removal have been studies to great degree
both by private and EPA funded research. Many technologies are
available for color removal. However, there is some controversy over
analytical measurement techniques proposed for the industry.
f.tnTi'"'- Tl O1 * -
l\u I *«.'*-• i l'u- • *"
K;-prl £". i "'"; ' -
-------
DRAFT
Since color is an aesthetic problem and the technologies are available
for its removal, a relatively lenient requirement will be established
until sufficient data and agreement can be made on analytical technique.
195
NOTICt: These a-e •.c,:,;a;:v? :c::-:::r.e.i ;::n; In. c,' i^cn iiiferrcat'on in this
report anil arc subject lo c'..«,;ic liased u;on co.-iin:cnt: rcceivad anJ further
review by EPA.
-------
DRAFT
Category I: Wool Scouring
Table IX-1 summarizes the effluent characteristics of three mills
in this industry subcategory that have waste treatment, one of these is
a pilot plant. Plant A is a Southern mill with a waste treatment
facility a little over one year old; plant B represents the pilot plant
project sponsored by EPA at Barre Wool in Massachusetts; and plant B» is
a central Texas mill.
A number of wool scouring mills were investigated to determine a range
of water use for this subcategory. The values ranged from 0.2 to 4.0
gal/lb of raw grease wool with a median water use of 1.5 gal/lb. A
scouring bowl train designed for complete counter current operation
which is normal practice in the industry uses 0.5 gal/lb, however, there
are variations from plant to plant. Water use value per unit of
material of exemplary plant A is influenced to an unknown extent by
cooling water. Plant B could reduce its water use by about 35-40
percent if it were to employ a complete counter current operation.
Another plant contacted indicated a present water usage of 0.7 to 1.0
gal/lb with intentions of future water reduction to 0.5 gal/lb.
The water use for wool scouring should not exceed 1.5 gal/lb when normal
operating procedures are employed.
Although Plant A appears to be performing well, it has had a history of
failures. There is indication based on several months data that the
plant can operate at a much higher efficiency. Four monthly averages
for BOD5 from 1972 are 150, 100, 15 and 22 mg/1. The last value, 22
mg/1, was the value indicated on the permit application as being the
average concentration in the effluent.
Two methods are available for no discharge of pollutants. One is total
containment as exemplified by exemplary plant B1. The other is direct
incineration. The high concentration of BOD5_, COD and grease makes this
an excellent candidate for incineration. This coupled with the
difficulty of waste treatment, either chemically or biologically, makes
it even more attractive. Looking at the 1985 goal of no discharge;
incineration, where land is unavailable, should be of serious interest
for a mill considering substantial treatment plant investment at the
present. Nevertheless, a biological treatment plant can reduce BOD5 to
an effluent concentration less than 150 mg/1. Other than total
containment, present treatment of wool scouring wastes are uniformly
inadequate. Therefore, a water use of 1.5 gal/lb (normal practice)
196
icviov; !•» Ci <••.
-------
.£ S
Q
TABLE IX- 1
PERFORMANCE OF MILLS WITH TREATMENT
Category 1: Wool Scouring
Raw BOD
Treated BOD
BOD Removal
_ _ _
rng/1 kg(1b)/1000 kg(T5T mg/1 kg(1b)/1000 kg(1b) prod. Efficiency (%)
2500
2700
B'
135 100-200
90 200-300
No Discharge
(total containment)
8
8.1
90-95
90
Production
kg(1b)/d
Water Use ;=" -'
Vkg(ga1/1b)j I
19,666* 33. 4-75.4'
(40,000-65,000) (4)
29,510 170 25-29.3
(65,000) (375)* (3-3.5)
45,000 18
(100,000) (1.5)
* Pilot plant capacity 4920 1 (1300 gallons) H20/day 4920 » 170 kg (1300 = 375 lb^ equivalent
proc-jction. ?878 V3.46 '
-------
DRAFT
coupled wirh an refluent concentration of 150 mg/1 results in an
effluent limitation of 1.9 lb/1000 Ibs.
COD
Much of the COD in the effluent from treatment systems A and B is
associated with the suspended solids in the effluent. For biological
systems efficient removal of suspended solids will result in maximum
removal of COD. The pilot plant at Barre approaches 1500 mg/1 COD in
the effluent. Although suspended solids removal through the system is
not high and the efficiency could be improved, a value of 1500 mg/1 COD
in the effluent will be employed. The effluent guideline for COD is 19
lb/1000 Ibs.
Suspended solids
Data from the two treatment facilities with effluent indicate that
suspended solids can be reduced to below 100 mg/1. The guideline based
on this information is 1.3 lb/1000 Ibs.
Grease
Grease is a serious problem in the wool scouring subcategory. It has
been shown to be recoverable and treatable. Effluent levels observed at
Barre Wool indicate less than 100 mg/1 in the final effluent. The
guideline based on this information is 1.3 lb/1000 Ibs.
The guidelines for the wool scouring category are based on pounds of
grease wool as received and weighed at the plant.
198
MmCC: Thcss c-c ^.[=:-.: rearr.n-cvsr.rs ba .c • ,-:ifl •Mi:~^l ,,, lhs
report a-i a* sf.;Kt :«, c'w.-.c !K;: t.-o- co.B:rc.-;:3 ;:;e.v£j mj ,a,,ku
review ty CPA.
-------
DRAFT
Category 2: Wool Finishing
BOD Guidelines
No truely exemplary plants were found from which to draw data for
establishing Level I guidelines. Water use for normal practice in this
industry subcategory falls in the range of 10 to 40 gal/lb, the latter
figure being influenced to an unknown extent by cooling water. For
processes considered to be normal for wool finishing, a reasonable water
use is 20 gal/lb. Waste water treatment facilities treating waste
partially composed of wool finishing wastes have shown consistent
reduction of BOD5 to below 20 mg/1. Combination of these values results
in an effluent guideline of 3.U lb/1000 Ibs.
COD
Reduction of COD to values below 200 mg/1 has been demonstrated. This
coupled with reasonable flow rate results in an effluent limitation of
3* lb/1000 Ibs.
Suspended Solids
Plants attaining a high level of BODJij and COD reduction will also by
necessity attain high reduction of suspended solids. Effluent
concentration of 30 mg/1 results in an effluent guideline of 5.1 lb/1000
Ibs.
Category 3: Greige Mills
As described in Section IV, plants of this type are essentially a dry
operation. Most Greige goods mills discharge their waste to sanitary
systems. Of the mills that treat their own waste most combine their
sanitary and industrial waste loads; the respondees to the ATMI
questionnaire indicated that 70 to 90 percent of the load was sanitary.
The only current compilation of water use figures for various textile
subcategories is that presented to EPA by the American Textile
Manufacturers Institute and the Carpet and Rug Institute. Although it
has not as yet been completely verified, it appears to present the full
range of water uses to be expected for each subcategory. Water use
distribution for greige mills as shown in Figure IX-2
illustrate an extremely wide variation. This can be explained by the
overriding influences of nonprocess water such as boiler water, cooling
water and sanitary wastes which are very significant in some cases and
less significant in others.
199
NOTICE: Tftcsa are '.snb'Va rexr.r.sr. 'ctVn: I-JTC ' y.-i r:.;Crmation in this
icport aaJ sr? sirred ',". IK::'.;.C !.c:c: a. n i:-:~; (.:.'.-, r;:c''v:J ail 'utV.mr
review by CPA.
-------
10
LU
CO
D
cc
LU
x x
x x
X X
XX
XX
ATMI DISTRIBUTION OF WATER USE
FIGURE IX-2
10-2
III III I I I I I I I
2 5 10 20 30 40 50 60 70
(PERCENT)
80 90 95 98
-------
DRAFT
Because of Lhc- extr*-..ie influence of nonprocess waste water on greige
mill wastes and the difficulty of relating the true industrial waste to
production it is recommended that some flexibility be permitted.
Calculations for permit conditions may need to be based on an effluent
concentration until such time as the true industrial waste is
identified.
BOD
It has been demonstrated that BOD can be removed to a level below 20
mg/1 consistently for a greige mill waste. From the water usage
distribution presented, it can be seen that the apparent median value is
extremely sensitive to the number of samples selected. That is, if two
additional values had been included with lower than median water use,
the median water usage would drop to 0.60 gal/lb; however, if two values
had been included with higher than median water use, the median would
shift to 1.3 gal/lb. Based on interpolation between the asymptotes
approached by the extremes the median value for water use is 0.62
gal/lb. Using a median water use of 0.62 gal/lb and an effluent
concentration of 20 mg/1 the effluent limitation is 0.1 lb/1000 Ibs.
COD
A long term average ratio of COD/BOD for one greige mill effluent is
7.8. On this a guideline of 0.78 lb/1000 Ibs. is calculated.
Suspended Solids
Suspended solids are reduced to an average of 30 mg/1. Effluent
limitation guidelines for suspended solids is 0.15 lb/1000 Ibs.
201
;:S;: *«:,' ?* « «. - -- -* - ««
review by EWV.
-------
DRAFT
r_ttegory 4: Woven Fabric Finishing
Water Usage
The water use distribution for this subcategory has been compiled by
the American Textile Manufacturers Institute and the Carpet and Rug
Institute. From the graphical distribution of Figure IX-3 it is
observed that 90 percent of this subcategory uses less than 30 gal/lb,
50 percent use 13 gal/lb, and 15 percent use less than 4 gal/lb.
BOD Guidelines
Table IX-2 summarizes the BOD effluent results from 8 mills
broadwoven, cotton and cotton blend finishing considered as exemplary
for category U. As stated earlier, this category represents the biggest
wet processing mills and the biggest water users in the textile
industry, and accounts for almost half of the pollution of this
industry. These were the first to be regulated by the states relative
to instituting waste abatement procedures, and as a result there are
many more good plants to consider as exemplary.
The mills all have above 92 percent BOD efficiency. Because of their
unique product mixes (varying ratios of cotton to synthetics and varying
weights of goods), and differing processing steps involved, the raw
waste loads varied from 35 kg (lb)/1000 kg (Ib) to 145 kg (lb)/1000 kg
(Ib) and the water usage is highly varied. (For example, the highest
water usage mill, S, processes all corduroys, velvets, and velveteens.
Even so, because of the high efficiency of waste treatment, all the
mills averaged less than 30 ppm concentration of BOD.
With six major pollution-contributing process steps and the significant
difference in BOD load between cotton and synthetics, literally hundreds
of combinations of plant sequences are possible and indeed do exist.
(See Sections IV and V.) It is felt that the plants cited in Table IX-2
cover the extremes in terms of processing conditions, and because of the
high treatability of this waste, no further subcategorization is
warranted.
The average of the best gives an effluent limitation of 2.2 lb/1000 Ibs.
Inspection of the plant with the highest influent concentration reveals
that this plant can meet the requirement. Inspection of the plant with
the highest water usage (35 gal/lb) indicates that this plant can also
meet the requirement.
COD Guidelines
202
ic-pi,:'.
-------
DRAFT
Table IX-3 summarizes the correlations between COD and BOD for various
plants in category H using their monthly average results for BOD and
COD.
203
- •
J w" cuXe.t a> S W ~^ «.'«i co:r.r.x:-.!.-. rocc.voJ and further
review by EPA.
-------
O
40
30
20i
I1
UJ
V)
cc-
UJ
ATMI DISTRIBUTION OF WATER USE FOR
WOVENS AND GREIGE PLUS WOOVENS x
x
x
x x
X X
I I
J_ ^L I . I
5 10 20 30 40 50 60 70 80 90 95 98
PERCENT
FIGURE IX-3
-------
TABLE IX-2
BOD PERFORMANCE
Raw BODa
Mill
J
K
M
0
P
Q
R
S
mg/1
776
566
807
444
622
445
356
167
kg(lb)/1000
kg(lb) prod.
88
35
78
37
146
50
37
49
OF EXEMPLARY MILLS
Category 4: Broadwoven, Cotton and Cotton Synthetic Blends
Treated BOD
mg/1 kg(lb)/1000
kg(lb) prod
30
13
23.1
14
19.3
6.4
27
4.2
3.4
0.8
2.2
1.2
4.5
0.71
2.8
1.2
BOD Removal
Efficiency %
96.1
97.7
97.1
96.9
96.9
98.5
92.3
97.5
Production
kg(lb)/d
211,000
(465,000)
60 ,800
(134,000)
197,000
(434,000)
73,000
(161,000)
90,800
(200,000)
25,700
(56,600)
Water Use
Vkg(gaVlb)
113.4
(13.6)
61.7
(7.4)
96.7
(11.6)
69.2
(8.3)
230.1
(26.7)
110.9
(13.3)
104.2
(12.5)
294.3
(35.3)
(a) average.
O
-------
DRAFT
The last c^iumn in _nis table is the pooled results from five plants.
Of the four plants analyzed individually, only two have good
correlations of COD to BOD. The Plant 0 correlation is the best and for
its mix of chemicals used in operations, the intercept would suggest
that only about 10 ppm (best estimate, 7.8) of its BOD is nondegradable.
Taking the overall average ratio of 13.7:1 suggested by the composite
data would give a COD guideline of 2.2x13.7=30.1, say 30 kg (lb)/1000 kg
(Ib).
The analysis of the composite data of five plants suggest an industry
average of 150 ppm COD as nonbiodegradable. The regression equation for
the composite data is:
COD * 149.5 + 4.02 (BOD)
An average plant water use of 13.5 gal/lb and an average BOD5 effluent
concentration of 20 mg/1 gives the following COD limitations:
COD = 149.5 * 4.02 (20)
COD =230 ppm
which corresponds to 27 Ibs/1000 Ibs. This corresponds favorably with
the previous calculation, therefore, the effluent guideline for COD is
30 lb/1000 Ibs.
Suspended Solids
The best among the exemplary plants with respect to suspended solids are
summarized in Table IX-3. It can readily be seen from Table IX-4 that
design overflow rate should not exceed 300 gpd/ft2 for this waste. In
addition, it may be necessary in some cases to add polyelectrolytes to
maintain the desired effluent concentration. An effluent concentration
of 30 mg/1 gives an effluent guideline of 3.3 lb/1000 Ibs.
206
E L. :'.. ; ». s- ;.i •r.-'-ir'-.I'o.i in t!ife
..0[U: ..'.-„ ,c 4 * '- '^ '^ '.; .^..^ ;tcB«J anJ further
report and arc sul-,ca .0 k..jn0- —•« -,-•<
review by EPA.
-------
DRAFT
CATEGORY 4;
TABLE IX-3
SUMMARY OF EFFLUENT COD BOD CORRELATIONS
Months Data
BOD, ppm
COD , ppm
Correlation
COD, BOD
Correlation
coefficient
T
12
162.17
874.75
5.4
fair
Plants
M
6
25.5
214
8.4
very
poor
V
5
18.0
254.2
14.1
good
O
12
13.5
202
14.9
very
poor
Grand Avg.
Excl.K,Incl.U
31
15.48
211.84
13.7
good
.42
Prob. Correlation
above 0 92.6%
Slope COD/BOD 1.479
Intercept < * >,
ppm
634.9
.08
56%
N/A
N/A
.89
99.9%
10.9
57.2
.97
99.99*
14.39
7.8
.42
99%
4.02
149.5
(1)
Inferred COD at O BOD.
207
-------
DRAFT
TABLE IX- 4
CATEGORY U - SUSPENDED SOLIDS
Plant Average
M
O
Q
R
98
121
61.5
31
<3 mo.
only)
Std. Dev.
of Mo.Avg
50
N/A
8.0
Range of Monthly clarifier Overflow
Averages, ppm Cu m/m*/day (gal/ftz/day)
39-193
N/A
49-72
30-33
(3 mo.
only)
28.72
24.50
12.34
12.79
(705)
(600)
(303)
(314)
208
report ana <•'£ su:.
review by EPA.
°" cn l'"s
nJ lurthor
-------
DRAFT
category 5: Knit Fabric Finishing
Water Usage
From the water use information supplied to EPA by ATMI-CRI, Figure IX-U
was constructed. The range of water use does not appear to be great,
that is, 75 percent of this relatively small sample of the industry use
between 10 gal/lb and 30 gal/lb with a median use of 20 gal/lb.
BOD Guidelines
Five plants were originally considered for setting Level I guidelines;
their performance is summarized in Table IX-5.
209
NOTICE: These zrc* «e-.!.i;:"'---T.r ^'.-' :---T. ;:'T-V:"-.' in Shis
l&r.f.l! ;:•'.•.... ' • . •• • iv ' - ' :•!' f
-------
ATMI DISTRIBUTION OF WATER USE FOR KNITS
40
30
20
S 10
UJ
CO
cc
111
X X
X X
o
K
I I
I I
I
I
I
10 20 30 40 50^ 60 70 80
PERCENT
90 95
98
FIGURE IX-4
-------
TABLE IX-5
BOO PERFORMANCE OF EXEMPLARY MILLS
Category 5: Knits
Mill
W
X
Y
Z
AA
Raw BOD
rnq/1 kq(lb)/1000 kg(1b)
481 51.7
80
568
175
249
17.9
75.6
18.0
40.8
Treated BOD BOD Removal Production
prod mg/1 kg(lb)/1000 kg(lb) prod Efficiency % kg(lb)/d
37.5 3.61
2.0 .45
16.3 2.17
9.7 1.01
30.0 5.01
91.7 14,100
(31,100)
97.4 28,600
(63,000)
97.2 62,060
(136,700)
94.4 17,200
(37,884)
88.0 17,600
(38,800)
Water Use
l/kg(gal/lb)
107.5
(12.9)
224.3
(26.9)
132.6
(15.9)
102.5
(12.3)
193.4
(23.2)
;_• £ s
Q
-------
DRAFT
Plant AA was origin<-.j.ly considered -to be included among the exemplary
plants because it carried on a significant amount of fabric printing and
also had begun to use increasing amounts of flameproofing agent for
childrens1 knitwear and there were some thoughts that this may affect
the treatability of the waste (88 percent vs. 92-97 percent for the
other plants under consideration). However, further inquiry revealed
this plant operates its aerators alternately at 50 percent and at 100
percent of capacity to keep dissolved oxygen from getting too high and
also does not add nutrient to the waste load on a consistent controlled
basis. It also has relatively high overflow rates on the clarifier.
Among the remaining four plants significant differences can be seen
among the raw waste loads, 18 to 75 kg (lb)/1000 kg (Ib) of product, but
this is normal for the diversity of operations carried on among knit
mills. More specifically, the differences were not due to the product
mix of raw materials being processed, but rather to the unit operations
for the specific fibers being processed.
The average of the best results in a BOD5 limitation of 2.45 lb/1000
Ibs. The plant with the highest water" use easily meets this
requirement. The plant with the highest influent concentration also
meets the requirement.
Plant W, having the lowest efficiency of removal among these plants
(91.7 percent), in conjunction with having the second highest raw load,
52 kg (lb)/1000 kg (Ib), had the poorest effluent of the four, 37 ppm
BOD or 3.6 kg (lb)/1000 kg (Ib). This plant, as described in Chapter V
has excellent design and operating characteristics, including
equalization, nutrient addition, extended aeration, with high
concentration of biomass and one of the highest aeration power inputs in
the industry and primary and secondary clarifiers. The one failing of
this plant is the high suspended solids carryover from the secondary and
tertiary clarifier possibly because of the extensive use of dispersed
dyes in dyeing the nylon portion of this production (25 percent nylon,
65 percent nylon/acetate) and a relatively high proportion of goods dyed
to dark shades. This carryover is despite the fact that the clarifiers
are designed at 9.71 Cu m/d/m2 (239 gal/d/ft2) overflow from the
secondary clarifier and 13.0 Cu m/d/m2 (320 gal/d/ft2) from the
tertiary. The plant recognizes this problem, and this spring installed
a rapid-mix basin, flocculation basin, and metering equipment for alum
and polyelectrolyte addition prior to secondary clarifier. With this
added treatment it is achieving "50 to 75-80 ppm" suspended solids and
feels that when the system is optimized, it will achieve 25 to 50 ppm.
(Its laboratory settling tests indicate this system should average 25
ppm solids in the overflow.)
212
..„...•-.- • j •' • ••-. , Icrirs'.'on in
NOTICE: TUsc a;j -.c:':. v: re .^ .. -j • -- ^ ^ - -• ^ ^^_^ ^_
rej:cr! anJ s:o -u••0-' •'• - '"-" " -.-•••
review by tFA.
-------
DRAFT
A simple reyression Analysis was made of suspended solids on BOD for
Plant W«s effluent. Using that
relationship (which indicated 0.2 kg (Ib) BOD associated with each kg
(pound) of suspended solids carryover), the monthly average BOD was
adjusted downward to account for an average suspended solids of 25 mg/1.
This had the effect of dropping the average BOD from 3.61 to 2.45 kg
(lb)/1000 kg (Ib) product, bringing it in line with the other plants.
COD Guidelines
COD data in this industry category are very meager, only two of the
exemplary plants have such. Plant W has fairly extensive data with an
excellent correlation between monthly average COD and BODls in the
effluent;
COD kg (lb)/1000 kg (Ib) product = 2.60 + 11.21 (BOD);
This waste treatment plant removed 74 percent of the COD, the other
Plant Y, with less data indicating 69 percent COD removal. From the
Plant W data, the effluent limit is calculated to be 30.1 kg (lb)/1000
kg (Ib).
Suspended solids Guidelines
By checking the available data, high suspended solids in other plant-
treated effluents within the knit industry were confirmed, probably
because of the use of dispersed dyes (Table IX-6).
TABLE IX-6
SUSPENDED SOLIDS DATA, CATEGORY 5
Average SS 2nd Clarifier Upflow
mg/1 Cu m/d/mz (gal/d/ft«)
Plant W 101 9.74 (239)
Plant X 29 12.96 (318)
Plant Y 36 20.70 (508)
Plant Z 48 8.35 (205)
Plant AA 84 24.40 (600)
Based on the above discussion of the technology that Plant W can employ
to achieve 25 ppm suspended solids, a limit of 25 ppm seems appropriate.
This calculates to a guideline of 4.1 kg (lb)/1000 kg (Ib) product.
213
NOTICt-. TV.cso a:; 'cr'.r/vo ifo:-:r.-.cr.:.-.: c;;r. '.n H u.\n .i.li'rnv.tlon in Oils
rcpcil .nJ r.:o SJVvl '..i o';-.;.c I'J:-:.: u r;i :;•».•• f' iKf\.:.'. .1.1 SUittn
ILV.O.V !>•; U-.V
-------
DRAFT
Category 6: Carpet Mills Including Backing
Water Usage
The distribution of water use within the carpet industry is presented in
the Figure IX-5. Roughly 70 percent of the industry uses between 3
gal/lb and 12 gal/lb with a median water use of 6.5 gal/lb.
BOD Guidelines
Two mills are summarized in Table IX-7.
The average of the best results in an effluent limitation of 1.4 kg
(lb)/1000 kg (Ibs) .
COD Guidelines
A. small amount of data suggests that faculatative or anaerobic ponds in
conjunction with aerobic ponds achieve greater COD reduction than do
aerobic ponds alone. Using a COD/BOD ratio of 10:1 an effluent
limitation of 14 kg (lb)/1000 kg (Ib) is calculated.
Suspended Solids
Data on the suspended solids performance of the two" plants of Table
IX-7 are very meager and are summarized below:
211
-------
DRAFT
Clarifier Dpflow Rate
Average Cu m/m*/day (gal/ft*/day)
Plant CC 17 8.026 (197)
Plant DD 40 12.13 (305)
Through proper design of a clarifier, it will average 30 mg/1 suspended
solids, therefore, an effluent limitation of 1.6 lb/1000 Ibs.
215
-------
21
CO
cc
Ul
I
40
30
20
10
ATMI DISTRIBUTION OF WATER USE FOR CARPETS
x *
,* *
X*
X
111 I I I I I I I
2 5 10
20 30 40 50 60 70 80
(PERCENT)
90 95
98
FIGURE IX-5
-------
DRAFT
Category 7: Stock and Yarn Dyeing
Hater Usage
A fairly wide distribution of water use is observed in the stock and
yarn dyeing subcategory. From the information supplied by ATMI-CRI,
roughly 85 percent use less than 30 gal/lb. A median water use of about
20 gal/lb is observed. From Figure IX-6, it is also observed that the
water use falls off rapidly indicating that 30 percent use less than 10
gal/lb.
BOD Guidelines
Two mills were considered exemplary relative to setting Level I
guidelines, as shown by their effluent characteristics in Table IX-8.
Two parameters, raw waste load and water usage, immediately suggest that
there may be basic differences between Plant EE and Plant GG. Plant EE
processes 100 percent PE and does piece dyeing to later achieve space
dyeing effects. It processes pure synthetics, and does not bleach or
mercerize. Plant GG processes PE cotton blends.
The average of the best results in an effluent limitation of 2.75 kg
(lb)/1000 kg (Ibs). Exemplary Plant GG approaches the guideline even
though it uses more water than 94% of the stock and yarn category.
COD Guidelines
Only one of the exemplary plants had any COD data. Three month's data
averaged 13:1 ratio of COD/BOD. From this the COD will average 35 kg
(lb)/1000 kg (lb), based on 13 times the BOD guidelines.
Suspended Solids
The average suspended solids concentration may be as high as 1.5 times
the effluent BODS concentration. This results in an effluent limitation
of 1.1 Ibs/1000 Ibs.
217
NOTICl: U.tre a;c :t»ia; vj ic :;•-:: c:. .:„.:. i; fj c,. n mrori-.I'on in Mils
report a:iJ tic su'jjccl lo c;.c:i.;c l::e; u;c:i t3;:;:rcn:-; rccovoJ anj further
review by EPA.
-------
100
90
80
70
60
50
40
30
20
s
UJ
CO
cc
Ul
I
10
ATMI DISTRIBUTION OF WATER USE FOR STOCK & YARN;
•-•&
J»«*
11
t- "u
rf g
i t
«» wt
O «i
r
I
I
I
I I
10 20 30 40 50 60 70 80
(PERCENT)
FIGURE IX-6
90 95 98
-------
TABLE IX- 7 :
BOD PERFORMANCE OF EXEMPLARY MILLS ; ;
Category 6:Carpet Mills
Raw BOD Treated BOD BOD Removal Production Water Use '
Mill mg/1 kg(lb)/1000 kg (Ib) mg/1 kg(lb)/1000 (Ib)prod. Efficiency % kg(lb)/d I/kg (gal/lb) -
CC 186 16.01 12.9 1.09 93.1 86.7 '' *
(10.4) » «
DD 280 9.6 14.0 0.5 95.2 31,330 54.2 •' "]
(69,000) (6.5) •-. -J
-------
DRAFT
SUMMARY OF EFFLUENT GUIDELINES FOR LEVEL I
Table IX-9 summarizes the guidelines, giving the not-to-exceed limits
based on 30 working day average, and maximum daily average.
220
. t t • • r rKOi.iM-.oa.a; ;ns .2 c. u;cn -ntor.Ta; on m ti;li
dte subiecuo change base; u.-on co,,cn-, «^td and «ur,hW
review by EPA.
-------
TABLE IX- 9
PERFORMANCE OF EXEMPLARY MILLS
CategoryT: Stock ?> Yarn Dyeing ?< Finishing
Hill
EE
GG
Raw BOD
mg/1 kg(lb)/1000 kg (1b)
Treated BOD
mg/1 kg(lb)/1000 kg (1b)
333
115
25.6
52.9
22.8
8.0
1.75
3.73
BOD Removal
Efficiency %
93.2
92.9
Production
kg(lb)/d
19,430
(42,800)
8,720
(19,160)
Water Use
I/kg (gal/lb)
76.7
(9.2)
461.0
(55.3)
-------
TABLE IX-T
LL*
SUMMARY
OF LEVEL I
Maximum 20
~ 13
POLLUTANT GUIDELINES - (a) •* *
j
Working Day Averages,
kg/1000 kg
1.
2.
3.
4.
5.
6.
7.
Category
Wool Scouring
Wool Finishing
Greige Goods
Woven Fabric Finishing
Knit Fabric Finishing
Carpets
Stock and Yarn Oyeing
BOD
2.85
5.1
0.15
3.3
3.6
2.1
4.0
COD
28
51
1
45
45
21
52
(lb/1000 Ib)
Suspended Solids
2.0
7.6
.17 0.22
6.1
6.1
2.4
6.1
PH^*3) '.'
6-8.5 ' '•
6-8.5
6-8.5
«j
6-8. 5 , .$
\ \i
"j <
6-3.5 : fc
^ >^
-J w -°
6-8.5 - ; 3 1
H ; -
6-8.5 N
(a) In addition to the guidelines shown, the following apply to all categories
Coliform organisms 200/ml '1PN,
Total chromium-not to exceed 0.25 mg/1
Phenols-not to exceed 0.25 mg/1
Color-not to exceed 200 ADMI units
(b) Values are the maximum permitted range.
Note: Daily maximum may not exceed twice the maximum 20 working day average.
Q
-------
DRAFT
REFERENCES
IX.1 Waste water treatment Technology—Second Edition, January
73-state of Illinois, Institute of Environmental Quality.
IX.2 28th Annual Purdue Industrial Waste Conference, Lafayette,
Indiana, May, 1973, page 13.
IX.3 Industrial Wastes Studies Program, Textile Products,
Arthur D. Little Draft Report to EPA, May 1971.
222
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DRAFT
SECTION X
BEST AVAILABLE TREATMENT ECONOMICALLY ACHIEVABLE
Introduct ion
Congress has stated that* "not later than July 1, 1983, effluent
limitations for categories in classes of point sources, other than
publicly owned treatment works, which . . . shall require application of
the best available technology economically achievable for such category
or class, which will result in reasonable further progress toward the
national goal of eliminating the discharge of all pollutants". The
Environmental Protection Agency has interpreted this section of the law
as follows: "Level II technology is not based upon an average of the
best performance within an industry category, but is to be determined by
identifying the very best control and treatment technology employed by a
specific source within the industry category, or subcategory, or where
it is readily transferable from one industry to another, such technology
may be identified as Level II technology."
In qualifying statements, the EPA has stated, "it is imperative that the
effluent limitation and standards to be promulgated by the Administrator
be supported by adequate verifiable data and that there be a sound
rationale for the judgments made." Further in the same document it is
stated, "However, Level II may be characterized by some technical risk
with respect to performance and with respect to certainty of cost.
Therefore, Level II may necessitate some industrially-sponsored
development work prior to its application."
We have been swayed by the words of Congress: "which will result in
reasonable further progress toward the national goal of eliminating the
discharge of all pollutants."
223
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DRAFT
Proposed Guidelines - zero Discharge
In most case.^ a 50% reduction in water usage from the average of the
plants in each category is projected.
From the rationale described previously, it is apparent that Level II
guidelines can be achieved only by the use of technologies beyond
biological treatment.
Achieving zero discharge is a primary aim of the law. In doing this,
careful consideration was given to all the advanced treatment
alternatives described in Section VIII-5—: phase change, membrane
separation and sorption—together with the cost information described in
Section VIII. Data showing the application of these technologies to
textile waste effluents is scarce, and a wide variety of chemicals may
be used by the industry. Therefore, the most promising techniques are
(a) secondary biological treatment, followed by (b) clarification to
reduce suspended solids, and (c) three stage evaporation or reverse
osmosis (see figure X-1).
In making recommendations for Level II guidelines, it should be recalled
that guidelines may be characterized by some technical risk.
Level II guidelines of zero discharge are chiefly directed at removal of
dissolved salts so that the water is fit for recycle. For removal of
these dissolved salts we have considered electrodialysis, ion exchange,
reverse osmosis, distillation, freezing techniques and ultrafiltration.
(The last two were eliminated from further consideration because of
their limited applicability and lack of technical data.)
Electrodialysis and ion exchange are more mature technologies and
similar in that they remove only dissolved, ionized salts. With this
limitation it is less likely that the treated effluent can be
successfully recycled to the process, because of the presence of color
or other residual organics or non-ionized salts, such as phosphates.
Reverse osmosis and multiple effect evaporation should have an advantage
over the former two processes since they remove organic materials in
addition to dissolved salts.
In Section VIII we have made detailed cost estimates of these two
processes as final treatment steps to obtain zero discharge. The
examples chosen were from category U, Woven Fabric Finishing, and
category 5, Knit Fabric Finishing, which represent the major proportion
22U
• Oil"-: • i-.-j i-c e..;...; rcco;:ii-.:cn;a; ens -c cj u.:cn ,ii!or:ra:.on in this
re,,ort anJ arc sut;ect :o c.^an^c tascj upon com.rents receded and further
review by EPA.
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DRAFT
Raw Wastewater
Primary Screening
Aeration
Stabilization
Basin
Condensate
Water Returned
to Process
(Or Reverse Osmosis Unit)
Solids to
Land Fill
FIGURE X-l SCHEMATIC FLOW DIAGRAM OF
PROCESS STEPS ZERO DISCHARGE
TREATMENT
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DRAFT
of the elfluent from the textile industry. The data show that the two
techniques are comparable in cost. Although reverse osmosis may have a
somewhat higher technical potential it needs more technical development.
The costs developed indicate $0.92 to 1.06/1000 liters ($3.50 to
U.00/1000 gallons) for large plants (including credit for water recycled
to the process) .
225
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SECTION XI
NEW SOURCE PERFORMANCE STANDARDS
& PRETREATMENT STANDARDS
New Source Performance Standards
As stated earlier, it is not clear how the textile industyr can reduce
its raw waste loads except by: (a) substitution of treatment chemicals
and (b) better process control to minimize reworks, poor dye bath
exhaustion, and wastage of process chemicals in general, as discussed in
Section VII.
A new plant should practice counter current flow and multiple use of
process and wash waters. These will reduce hydraulic loads and for a
new waste treatment plant will permit reduced size or longer residence
times but will offer few opportunities to recover chemicals (and thereby
reduce waste loads).
However, with Level I guidelines, treated effluent BOD concentrations
will already be below 30 mg/1 (ppm) using standard biological treatment
plants. Functionally, there is little reason to lower this BOD load
still further.
It is recognized that in settling standards for Level II, a ten year
period is built in to collect better data on reliability and cost of the
newer abatement technologies, whereas Level III guidelines are to be
applicable essentially immediately. Even so, it is recommended that the
Level II guidelines be applied as Level ill guidelines as well.
Pretreatment Standards
Waste waters from the textile industry have been shown to be
biologically degradable under appropriate conditions. Consequently,
treatment of these waste waters in municipal sewage systems could be
expected to proceed in an analogous manner if appropriate pretreatment
and operating considerations are used. Although the BOD portion of
these waste waters has been found to be generally as treatable as
municipal sewages, the normal operating conditions for the municipal
waste water treatment plants may require modification. Furthermore, the
COD of the effluent from the combined municipal and industrial waste
water treatment plant can be expected to be higher than that normally
226
NOTICE: T1 fis s:s 'c pr'v. :.r.--—~c- -.; '.-•• 'so! ;: -p T.hrr.a'.'on in this
K;-O:( sin ?;c ;a":c:l s : ; c .vc: i •;•: <:.,•:•'• .— v^j aad further
tc-ACv. b; LI''A.
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DRAFT
associated with nr.iiicipal sewage because of the more biological
refractory substances found in the industry waste water. Obviously, the
proportion of the total flows and loads contributed by the industry
source as well as the treatability must be evaluated for each location.
If those conditions are recognized and appropriately compensated for,
the pretreatment requirements for the waste water from the textile
industry should be as follows.
1. suspended solids that will settle out in sewer lines or
accumulate on surfaces should be removed by a screening operation before
entering the system. (Short fibers are the principle contributor here.)
2. pH should be adjusted before the waste waters are discharged to
municipal sewers.
3. Heavy metals should be removed to levels established for the
industry category except appropriate allowances may be made for those
metals known to be removed in efficiently operating biological systems.
Approximately two-thirds of the chromium, the metal of most concern for
textile waste, is removed in the waste treatment plant so pretreatment
standards should be set according to the percent of the total waste that
is represented by the textile load with a maximum of, say, 2 mg/1 (ppm).
H. Toxic and hazardous substances should be precluded.
Presumably, their usage within the industry's plant will have been
restricted by the EPA*s toxic and hazardous materials, rules and
regulations.
5. Waste waters should be collected at the plant site, cooled if
required, and metered into the municipal sewage system at a rate and
schedule compatible with the diurnal characteristic of the system.
6. Removal of colloidal solids at the industrial plant to a level
commensurate with those established for the industry category. (One
principal item here is latex removal by adjusting pH and coagulating it
in carpet mills.)
7. Floating oils should be removed prior to putting the waste
waters into municipal sewer systems.
The pretreatment guidelines suggested above for textiles are compatible
with the preliminary report "Pretreatment Guidelines for the Discharge
of industrial Wastes to Municipal Treatment Works" by Roy F. Weston,
Inc. (EPA Contract No. 68-01-03*6); however, the later report should be
227
.! ....' .arlhsr
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DRAFT
consulted for the Comprehensive background and rationale to be followed
in establishing pretreatment standards for industrial plants.
228
tlOTiCf.: T'-cc; C"C '<•"•<."»•: re'.:i~r"cri.'r' :r,; V- c.' c;-.n .n::rn:a.:cn in this
r-;.!-. .in-' &:i: 'U-.W .i -' ."• : :^-'-' ""•" ::•••'•'• ""'.' ::?':- .r;J farther
rcvxv: LV Si'A.
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DRAFT
SECTION XIII
ACKNOWLEDGMENT
Field data and much other information contained in this report has been supplied by
A. D. Little, Inc., under EPA Contract No. 68-01-1515.
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DRAFT
SECTION XIV
REFERENCES
A review of the recent literature for references on Textile wastes and
waste treatment has produced over 200 references. Brief abstracts of
50 of these references are included as well as the full list of references.
This review covered the following:
SOURCE
Abstracting and Indexing Services
Applied Science and Technology Index
Chemical Abstracts
Engineering Index
Pollution Abstracts
Textile Information—Sources and References
Water Pollution Abstracts
Journals
American Dyestuff Reporter
America's Textile Reporter Bulletin
Bulletin Environmental Contamination;
Toxicology
Environment
Environmental Science & Technology
Industrial Waste
Industrial Water Engineering
COVERAGE THRO
March 1973
April 9, 1973
November 1972
March 1973
June 1972*
July 1972*
March 1973 (except Aug. 1971)*
January 1973 (except Feb. and
April 1972)**
June 1972**
November 1972***
March 1973 (except Jan. and
Feb. 1973)**
March/April 1973***
April/May 1973***
229
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DRAFT
Textile Chemists ana Colorists
(J. Am. Assoc. TCC)
J. Environmental Sciences
Modern Textiles
Pollution Engineering
Textile Industries
Textile Institute and Ind. Proc.
Textile Month****
Textile Research J.
Textile world
Water and Wastes Eng.
Water and Sewage Works
Water Pollution Control Federation J.
Water Research
April 1973
March/April 1973 (except
May/June 1972)**
March 1973
July/August 1971, Sept./Oct.
1971; January/February, March/
April, July, August, September
and November 1972***
January 1973 (except June 1971,
June and August 1972)**
October 1972*
March 1973
March 1973
April 1973
July 1972, plus January 1973,
(except November 1971, January
March, August-December 1972)**
February 1973 (except April
and September 1972)**
January 1973 (including Textile
Waste Bibliographies, June
1971 and 1972)
April 1973
*Latest in ADL Library
**Missing from ADL Library
***Only available issues in ADL Library
****Most textile journals covered only industry-related topics, so
coverage was limited.
Other journals (CIBA Review, Environmental Pollution and control. Water
230
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DRAFT
and Wastes Digest, Lnvironment Report, etc.) , were checked briefly only
to confirm that they did not cover the subject of textile waste treatment.
231
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DRAFT
Bibliographies
The bibliography contained in: "The Cost of Clean Water, Volume III
Industrial Waste Profile No. U - Textile Mill Products," Federal Water
Pollution Control Administration, September 1967.
The bibliography contained in: "State of the Art of Textile Waste
Treatment," Water Pollution Control Research Series 12090 ECS 02/71.
The bibliography contained in: The Report for "The American Manufacturer's
Institute," by Institute of Textile Technology and Hydroscience, Inc.
January 15, 1973.
Aside from documenting design parameters and operating data for existing
conventional waste treatment plants, the literature review did not produce
a wealth of information of direct use to this case. Most of the experience
with more advanced waste treatment methods such as reverse osmosis, carbon
adsorption, ozonation, radiolysis, and ion exchange, was confined to
either laboratory or pilot plant operations. Due to the variation in the
characteristics of the waste to which these methods were applied, meaning-
ful generalizations as to their cost and effectiveness cannot be readily
made.
The review did reinforce some already known facts about textile waste
treatment in general.
1. Present biological treatment methods, while capable of reducing BOD
concentrations to low levels show relatively poor performance with
respect to COD and color.
2. While much success has been achieved with carbon adsorption on many
wastes, one cannot make a blanket statement that it will reduce COD
or color to low levels in all cases. Very often it is only partially
effective and/or economically feasible.
3. Presently employed textile waste treatment methods are largely con-
fined to conventional biological treatment such as activated sludge
or aerated lagoons.
232
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DRAFT
(2) "The BOD of Textile Chemicals, Updated List - 1966"
American Dyestuff Reporter, (55) No. 18, 39-42, 1966.
(self-explanatory)
(15) "What the Mills are Doing to Control Water Pollution"
Textile Chemist and Colorist, (1) No. 6, 25-36, 1969.
This article gives a brief rundown of waste control activities at:
1. American Enka, N.C. facility, where rayon, nylon, and
polyester are produced
2. Burlington Industries (general)
3. Cannon Mills (discussed new design in detail)
4. Cone Mills (general)
5. Dan River Mills (Danville plant)
6. M. Lowenstein S Sons (Lyman Printing and Finishing Co.)
(18) Molvar, A., C. Rodman, and E. Shunney
"Treating Textile Wastes with Activated Carbon"
Discusses activated carbon treatment in general, pilot plant
work, and actual operating data for a full size waste treatment
system. The mill's identity is not given (dyeing and finishing).
(21) Souther, R.H.
"Waste Treatment Studies at Cluett, Peabody S Company Finishing Plant"
American Dyestuff Reporter, (58) No. 15, 13-16, 1969.
Detailed operating data on the Arrow Co., Division at Waterford, New
York. The treatment system consists of an "extended-contact,
activated sludge step, bio-aeration process." Also includes caustic
recovery.
(22) "Wastewater Treatment Recycles 80 Percent of Industrial Flow"
American Textile Reporter, (83) No. 51, 14-15, 1969.
233
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DRAFT
Very brief description and general flow diagram of the waste treat-
ment system using activated carbon at Hollytex Carpet Mills (near
Philadelphia). No real operating data is given.
(25) Jones, E.L., T.A. Alspaugh, and H.B. Stokes
"Aerobic Treatment of Textile Mill Waste"
JWPCF (34) No. 5, 495-512, 1962.
Cone Mills, joint treatment of mill and municipal sewage by
contact stabilization process. (Pilot plant operating data.)
(47) Poon, C.P.C.
"Biodegradability and Treatability of Combined Nylon and
Municipal Wastes"
JWPCF (42) No. 1, 100-105, 1970.
Treatability study of wastes taken from the fielding Chemical Co.
in Thomaston, Connecticut. Strictly a laboratory study.
(49) Kwie, W.W.
"Ozone Treats Wastestreams from Polymer Plant"
Water and Sewage Works, 116, 74-78, 1969.
Laboratory study on ozone treatment of wastes from polymer plant
(including SANS). The study did not produce very satisfying results.
(52) Wheatland, A.B.
"Activated Sludge Treatment of Some Organic Wastes"
Proc. 22nd Ind. Waste Conf. Purdue Univ. 983-1008, 1967.
Treatability study on a simulated synthetic fiber production and
dyeing waste using a bench scale activated sludge unit.
(53) Carrigue, C.S., and L.U. Jauregui
"Sodium Hydroxide Recovery in the Textile Industry"
Proc. 22nd Ind. Waste conf. Purdue Univ., 1966.
Castelar Textile Mill, Argentina (cotton goods)
Description of NaOH recovery from the mercerizing process. NaOH
is filtered and then concentrated by evaporating. Design criteria,
operating data and capital and operating costs are given.
(56) Taylor, E.F., G.C. Gross, and R.F. Rocheleau
"Biochemical Oxidation of Wastes from the New Plant for Manufacturing
Orion at Waynesboro, Va."
234
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DRAFT
Proc. Ibth Ind. .vaste Conf. Purdue Univ., 1961.
Detailed description of Dupont's Waynesboro works. Waste facilities
consist or a catalytic oxidation unit which completely oxidizes the
organics associated with the recovery of dimethylformamide and an
activated sludge unit for treatment of dilute organic materials such
as aeryIonitrile, dimethylformamide and formic acid.
(57) Sadow, R.D.
"The Treatment of Zefran Fiber Wastes" (acrylic fiber)
Dow Chemical Company's Williamsburg, Va., plant. Description of
waste treatment process which includes primary settling, chemical
coagulation, a Dowpac oxidation tower, and secondary settling.
Operating data and design criteria are given.
(61) Jones, L.L.
"Textile Waste Treatment at Canton Cotton Mills"
JWPCF (37) No. 12, 1693-1695, 1965.
Gives a rather brief description of their activated sludge unit with
design criteria, operating data (sketchy) and cost information.
(62) Smith, A.L.
"Waste Disposal by Textile Plants"
JWPCF (37) NO. 11, 1607-13, 1965.
Very general article, gives some synthetic textile waste characteris-
tics and very brief descriptions of waste characteristics and treat-
ment methods at:
1. Chatham Manufacturing Co., Elkin, N.C. (multi-fiber woolen mill)
2. J.P. Stevens Co., Wallace Plant
(63) Dean, B.T.
"Nylon Waste Treatment"
JWPCF (33) NO. 8, 864-70, 1961.
Operating experience of the Chemstrand Corp. Pensacola plant which
utilizes an activated sluge unit followed by a post-treatment lagoon.
(76) Suchecki, S.M.
"A Dyer's "Operation Cleanup"
Textile Industries (130) No. 6, 113, 1966.
235
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DRAFT
Description of northern Dyeing Co., Washington, N.J. treatment
facilities. Very little operating data given.
(86) Souxher, G.P.
"Textile Water Pollution Woes Can be Resolved by Solvents11
American Textile Reporter (54) No. 9, 11, 13, 1970.
Describes solvent sizing and dyeing processes. This is an infor-
mative but not very detailed article.
(95) Porter, J.J.
"Concepts for Carbon Adsorption in Waste Treatment"
Textile Chemists and Colorists (4) No. 2, 29-35, 1972.
The history of carbon's entry into the waste treatment field is
presented. Interpretations of teh fundamental kinetics and
thermodynamics of carbon adsoption are also given with several
specific examples cited.
(99) Rodman, C.A.
"Removal of Color from Textile Dye Wastes"
Textile Chemists and Colorists (3) No. 11, 239-47, 1971.
solutions of four types of dyestuffs were treated by several methods
that have been used practically or experimentally for color removal.
Among these were coagulation by lime and by alum; extended aeration,
activated carbon adsorption, reverse osmosis, and treatment with high
pressure oxygen and cobalt-60 radiation.
(100) Rhame, G.A.
"Aeration Treatment of Textile Finishing Wastes in South Carolina"
American Dyestuff Reporter (60) No. 11, 46, 1971.
Operating data of several unidentified plants is presented along
with general design criteria.
(103) Porter, J.J.
"Treatment of Textile Waste with Activated Carbon"
American Dyestuff Reporter (61) No. 8, 24-7, 1972.
Considerations in evaluating the potential application of carbon
adsorption to a waste stream are discussed along with procedures
for conducting laboratory studies.
(106) Stone, R.
236
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DRAFT
"Carpet Mill Incastrial Waste System"
JWPCF (44) No. 3, 1*70-478, 1972.
A description of the waste treatment system of the Halter Carpet
Mill, City of Industry, California is presented.
(108) Little, A.H.
"Use and Conservation of Water in Textile Processing"
Journal of the Society of Dyers and Colorists (87) No. 5, 137-15, 1971,
Investigation of water usages in unit processes under normal pro-
duction conditions. The effects of different dyeing and bleaching
processes have been studied. Possible methods of conservation of
water are discussed, including contra-flow washing. In addition,
the effects of changes in processing, the size, type and speed of
machines and the effects of cloth weight and batch size are discussed.
(110) Masseli, J.W., N.W. Massell, and M.C. Burford
"Factors Affecting Textile Waste Treatability"
Textile Industries for October 1971, p. 84-117
General design parameters of activated sludge waste treatment are
discussed along with startup and operational considerations. Waste
contributions (in terms of % total BOD) are given for the individual
process chemicals used in a typical cotton mill, cotton/synthetic
mill, and woolen mill.
(Ill) Shunney, E.L., Perratti, A.E., and Rodman, C.A.
"Decolorization of Carpet Yarn Dye Wastewater"
American Dyestuff Reporter (60) No. 6, 32-40, 1971.
Laboratory and full-scale operation of bio-regenerated activated
carbon treatment of carpet yarn fiber dyeing are discussed. The
facility described is the C. H. Masland S Sons plant in Wakefield,
Rhode Island.
(113) Rodman, C.A., and E. L. Shunney
"A New Concept for the Biological Treatment of Textile Finishing
Wastes"
Chem. Eng. Progr. Symp. Ser. 67, 107, 451-457, 1971.
(Same subject as ref. Ill)
(115) Rodman, C.A. and E. L. Shunney
"Novel Approach Removes Color from Textile Dyeing Wastes"
237
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DRAFT
Water and Waste 2ng. (8) No. 9, §18-23, 1971.
(Same subject as ref. Ill)
(118) "Bio-regenerated Activated Carbon Treatment of Textile Dye Wastewater"
Water Pollution Control Research Series 1209 OD WW 01/71.
(Same subject as ref. Ill)
(122) Powell, s.D.
"Biodegradation of Authraquinone Disperse Dyes"
Thesis, Georgia Inst. Tech., 9, 238, 1971.
Three authraquinone disperse dyes. Disperse Violet 1 (C.I. 61100),
Disperse Blue 3 (e.I. 61505), and Disperse Blue 7 (C.I. 62500),
were partially metabolized by bacteria normally present in domestic
activated sludge. Disperse Red 15 (C.I. 60710), was left unchanged
by the sludge. The nature of the metabolites produced showed that
the dyes had not actually been degraded, but merely converted to
derivatives of the original dyes.
(123) Hood, W.S.
"Color Evaluation in Effluents from Textile Dyeing and Finishing
Processes"
Initial concentration and rates of degradation of dyes and chemicals
in textile effluents were studied. Field studies were made to
observe conditions and to collect samples of water from streams in
the Coosa River Basin. The samples were analyzed for content of
specific dye auxiliaries and color. Color degradation was achieved
under simulated stream conditions, both in textile effluents and in
river samples.
(12U) Soria, J.R.R.
"Biodegradability of Some Dye carriers'1
Thesis, Georgia Inst. Tech., 9, 238, 1971.
Carriers covered in this study were resistant to degradation in
conventional activated sludge waste disposal plants. Where bacteria
were acclimated to the chemicals and treatment times were extended,
degradation did occur.
(125) Arnold, L.G.
"Forecasting Quantity of Dyestuffs and Auxiliary Chemicals Dis-
charged into Georgia Streams by the Textile Industry"
238
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DRAFT
Thesis- Georgia Inst. Tech., 9, 238, 1971.
The quantity and concentration of the major textile wet-processing
chemicalb in effluents are reported.
(126) Pratt, H.D., Jr.
"A Study of the Degradation of Some Azo Disperse Dyes in Waste
Disposal Systems"
Thesis, Georgia Inst. Tech., 9, 238, 1971.
Two azo disperse dyes. Disperse Orange 5 (C.I. 11100) and Disperse
Red 5 (C.I. 11215), were degraded by the bacteria in conventional
waste treatment facilities into aromatic amines. Biological de-
gradation produced identical metabolites as those formed by chemi-
cal reduction.
(127) Anderson, J.H.
"Biodegradation of Vinyl Sulfone Reactive Dyes"
Thesis, Georgia Inst. Tech., 9 238, 1971.
Biodegradation of three vinyl sulfone reactive dyes. Reactive
Blue 19, Reactive Violet 5, and Reactive Black 5, were investigated
under laboratory conditions simulating those employed in conventional
activated sludge plants. The study failed to show any evidence of
degradation. Reactive Blue 19, and Reactive Violet 5 showed evidence
of degradation under anaerobic conditions.
(141) "The Centrifugal Recovery of Wool Grease"
Wool science Review t37, p. 23-36, 1969.
This very detailed article discussed the composition of wool scour
liquor, general principles of recovery, detailed operating charac-
teristics of centrifuges, and the economics of wool grease recovery.
(143) Barker, R.P., and B.M. Rock
"Water Conservation and Effluent Disposal in the Wool Textile Industry"
J. Soc. Dyers and colourists (87), No. 12, 181-3, 1971.
Discusses the wool textile industry in the U.K. Gives water con-
sumption for various unit processes in terms of gal/lb product.
This article also gives typical wool processing effluents and a
description of the Traflo-W process which entails chemical coagu-
lation followed by vacuum filtration. BOD is reduced by 80*.
(149) Rea, J.E.
239
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"Treatment of Carpet Wastes for Disposal"
Proc. Industrial Waste and Pollution Conference and Advanced
Water Conference, ?2nd and 3rd. Oklahoma State University,
Stillwater, Oklahoma, March 21-30, 1971.
This paper identifies design criteria and operating data for the
waste treatment facilities at Sequoyah Mills in Anadarko, Okla.
The waste treatment facilities consist of an aerated lagoon and
stabilization pond. Pilot work is included which shows the re-
lationship of BOD removal to aeration time.
(150) Paulson, Per
"Water Purification - An Alternative to Solvent Dyeing"
International Dyer & Textile Printer - June 4, 1971.
A brief description of a new waste treatment process employing
sedimentation followed by ion exchange. Pilot plant work on
dyeing liquor showed COD removals greater than 90$.
(161) Kulkarni, H.R., S.U. Khan, and Deshpande
"Characterization of Textile Wastes and Recovery of Caustic Soda
from Kier Wastes"
Environmental Health (13) No. 2, 120-127, 1971.
A case study of "A Typical Cotton Textile Industry" is presented
in the paper with reference to economical method of treatment of
the waste waters and recovery of caustic soda during the process
of treatment. Ninety-eight percent caustic recovery has been
accomplished using dialysis.
(162) "Bi©degradation of "Elvanol" - A Report from Du Pont"
The report concludes that domestic and textile mill activated
sludge microorganisms can acclimate to "Elvanol" T-25 under con-
ditions attainable in conventional waste treatment systems and
that removals of over 90% can be achieved if the organisms are
properly acclimated.
(161) Ryder, L.W.
"The Design and Construction of the Treatment Plant for Wool
Scouring and Dyeing Wastes at Manufacturing Plant, Glasgow, Va."
J. Boston Soc. Civil Engrs., 37, 183-203, April 1950.
This article gives a very detailed description and design basis
for the waste treatment system consisting of equalization, acid-
240
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DRAFT
floccui?.-tion, ana neutralization. The plant achieves a BOD re-
moval of 60%, SS removal of 96% and a grease removal of 97%.
(168) Rodman, C.A., and E.L. Shunney
"Clean Clear Effluent"
Tex. Manufacturer (99) No. 49, 53-56, 1972.
A description of the Fram Corporation bio-regenerated carbon
adsorption process is given along with laboratory and pilot plant
operating data. The pilot plant treated waste water from the
carpet yarn fibre dyeing plant of C.H. Masland 6 Sons, Wakefield,
Rhode Island. A COD reduction of 81% and a color reduction of
99.4% is reported.
(175) Wilroy, R.D.
"Industrial Wastes from Scouring Rug Wools and the Removal of
Dieldrin"
Proc. 18th Ind. Waste Conf., Purdue Univ., April 30, May 1-2, 1963,
The article describes design considerations and operating exper-
ience of a waste treatment system consisting of fine screens,
sedimentation basin, and an anaerobic lagoon. A BOD reduction
of between 80 and 90% and a Dieldrin reduction of 99X is claimed
for the system.
(181) Stewart, R.G.
"Pollution and the Wool Industry"
Wool Research Organization of New Zealand, Report No. 10, 1971.
This article is a rather general outline of the sources of wool
processing wastes and the present waste treatment technology
available.
(190) Rebhun, M., A. Weinberg, and N. Narkis
"Treatment of Wastewater from cotton Dyeing and Finishing Works
for Reuse"
Eng. Bull. Purdue Univ., Eng. Ext. 137 (pt. 2), 1970.
This article describes the results of pilot plant work on the
waste from a cotton dyeing and finishing mill in Israel. Alum
flocculation followed by filtration was shown to produce a 95%
color reduction and a 67% COD reduction. Activated carbon was
shown to be a poor sorbent, and greater success was achieved
using a weak base ion exchange resins.
241
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(202) Alsps'ugh, T.A.
"Treating Dye Wastewaters"
45th Annual Conference of the Water Pollution Control Federation
Atlanta, Georgia, Oct. 8-13, 1972.
Alspaugh gives a very thorough evaluation of presently employed
and promising future waste treatment unit operations. Experienced
removal efficiencies and general treatment costs are also given.
A summary of current waste treatment research is given.
(213) Corning, V.
"Pollution Control in Jantzen Dyehouse"
Knitting Times (39) No. 35, 44-45, 1970.
Brief description of Portland, Oregon plant, little detail.
(214) "Textile Water Pollution Cleanup Picks Op Speed"
Textile World, 54-66, November 1967.
Fairly general arcicle but does give some operating data and waste
treatment descriptions for several plants:
1. J.P. Stevens 6 Co., Wallace, N.C. plant
2. OPD's Bluefield, Va.r plant
3. Burlington's Cooleemee, N.C.
4. Lyman Printing and Finishing Co., Lyman, N.C.
5. J. P. Stevens & Co., Utica-Mohawk plant
(215) Sahlie, R.S., and C.E. Steinmetz
"Pilot Wastewater Study Gives Encouraging Indications"
Modern Textiles, (50) No. 11, 20-28, 1969.
Description of pilot plant work at Fiber Industries, Shelby, N.C.
plant. Article is not very detailed.
(216) "Trade Effluent control in the Carpet Industry"
Textile Institute and Industry, (3) No. 9, 237-40, 1965.
General discussion, gives values for typical effluents.
242
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BIBLIOGRAPHY
1. Masselli, J.W., N.W. Masselli, and M.G. Burford, "A Simplification
of Textile Waste Survey and Treatment," New England Interstate Water
Pollution Control Commission, June 1967.
2. "The BOD of Textile Chemicals Updated List-1966," American Dyestuff
Reporter, (55) No. 18, August 1966.
3. Porter, J.J., A.R. Abernathy, J.M. Ford, and D.W. Lyons, "The State
of The Art of Textile Waste Treatment." Clemson University (FWPCA
Project 12090 ECS), August 1970.
U. "The cost of clean Water—Volume III, Industrial Waste Profile No. U
Textile Mill Products," FWPCA Publication No. I.W.P.-4, Sept. 1967.
5. "Water Pollution Control in the Textile Industry," Textile Chemist
and Colorist, 1, No. 7, 23-4H, March 1969.
6. "FWPCA Methods for Chemical Analysis of Water and Wastes," U.S.
Department Interior, TWPCA, Analytical Quality Control Lab.,
Cincinnati, Ohio, November 1969.
7. Davis, E.M., "BOD vs COD vs TOC vs TOD," Water and Wastes Engineering
(8) No. 2, pp 32-38, 1971.
8. "Standard Methods for the Examination of Water and Wastewater," 12th
Edition, American Public Health Association, New York 1965.
9. Eckenfelder, W.W. Jr., "Industrial Water Pollution Control," McGraw-
Hill Book Company. New York, 1967.
10. Shindala, A., and M.J. callinane, "Pilot Plant studies of Mixtures of
Domestic and Dyehouse Wastes," American Dyestuff Reporter, (59) No. 8,
15-19, August 1970.
11. Merrill, W.H. Jr., "How to Determine a Plant's Waste Load," Water
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12. Leatherland, L.C., "Treatment of Textile Wastes," Water and Sewage
Works, (116) R-210-21U, November 1969.
13. Eckenfelder, W.W. Jr., "Water Quality Engineering for Practicing
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243
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1ft. "Stretch knitter cuts pollution, triples dyehouse production,"
Textile World, (120) No. 2, 112-116, 1970.
15. "What The Mills Are Doing to Control Water Pollution," Textile
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16. Biggs, A.I., "Biological Treatment of Textile Effluents,14 Chemistry
and Industry, 1536-8, September 16, 1967.
17. Northup, H.J., "There are Some Answers to Textile Pollution," Journal
of the American Association of Textile Chemists and colorists, (2)
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18. Movar, A.E., C.A. Rodman and E.L. Shunney, "Treating Textile Wastes
With Activated Carbon," Textile Chemist Colorist, (2) No. 15, 35-39,
August, 1970.
19. Porter, J.J., "The Changing Nature of Textile Processing and Waste
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20. "Activated Carbon Reclaims Textile industry's Waste Waters," Environ-
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21. Souther, R.H., "Waste Treatment Studies at Cluett, Peabody and Company
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22. "Waste Water Treatment Recycles 80 Per Cent of Industrial Flow,"
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25. Jones, E.L., T.A. Alspaugh, and H.B. Stokes, "Aerobic Treatment of
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26. Jones, L.L. Jr., "Textile Waste Treatment at Canton Cotton Mills,"
2ftft
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DRAFT
American Dyestu_£ Reporter, (54) No. 22, 61-62, October 1965.
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29. Kwie, W.W., "Ozone Treats Wastestreams From Polymer Plant," Water
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40. Environmental Protection Agency—Contract 12090 DWM, Masland and Sons—
245
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"Demonstration .2 a New Process for the Treatment of Textile Dyeing
and Finishing Wastes."
41 Ibid—COL tract C ±2090 ESG, American Enka "Hydroxide Precipitation
and Recovery of certain Metallic Ions from Waste Waters.11
42. Ibid—Contract C 12090 GOX, Fiber Industries, "Reuse of Chemical Fiber
Plant Wastewater and Cooling Water Slowdown."
43. Ibid—contract 12090 EGW, Holliston Mills, "Treatment of Cotton Textile
Wastes by Enzymes and Unique High Rate Trickling Filter System."
44. Ibid—contract 12090 EQO, "Palisades Industries," Demonstration of a
New Process for the Treatment of High Concentration Textile Dyeing
and Finishing Wastes."
45. Ibid—Contract 12090 FWD, American Association of Textile Chemists
and Colorists, "The use of oxygen and ionizing radiation to decolorize
dye wastes."
46. Ibid—contract 12090 EOE, North Carolina State University, "The
Feasibility of Precipitation Removal of Synthetic Sizing Materials
from Textile Wastewaters."
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246
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247
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DRAFT
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248
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DRAFT
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249
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DRAFT
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103. Porter, J.J., "Treatment of Textile Waste with Activated Carbon,"
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250
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107. Aurich, C., C.A. Brandon, J.S. Johnson Jr., R.E. Minturn et al.,
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114. Nosek, J., "Complex Alkali Management During Purification of Cotton
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251
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119. Riggs, J.L., Adsorption/Filtration: A New Unit Process for the Treatme
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122. Powell, S.D., "Biodegradation of Anthraquinone Disperse Dyes,"
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124. Soria, J.R.R., "Biodegradability of Some Dye Carriers," Master's
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125. Arnold, L.G., "Forecasting Quantity of Dyestuffs and Auxiliary
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252
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254
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170. Little, A.H., "The Treatment and control of Bleaching and Dyeing
Wastes," Water Pollution Control, London, 68, 178-89, 1969.
171. Fathmann, D.H., "Solving the Effluent Problem in Textile Mills. I,"
Tex. (Neth.), (29) No. 12. 918-20, 1970.
172. Fathmann, D.H., "Solving the Effluent Problem in Textile Mills. II,"
Tex. (Neth.), (30) No. 1, 37-40, 1971.
173. Laurie, D.T., and C.A. Willis, "Treatment Studies of combined Textile
and Domestic Wastes."
174. Buswell, A.M., and H.F. Mueller, "Treatment of Wool Wastes," Proc.
llth Ind. Waste conference, Purdue University, May 15-17, 1956.
175. Wilroy, R.D., "Industrial Wastes from Scouring Rug Wools and the
Removal of Dieldrin," Proc. 18th Ind. Waste Conf., Purdue University,
April 30, May 1-2, 1963.
176. Snyder, D.W., "Dow Surfpac Pilot Study on Textile Waste," Proc. 18th
Ind. Waste Conference, Purdue University, April 30, May 1-2, 1963.
177. Stack, V.T., "Biological Treatment of Textile Wastes," Proc. 16th
Ind. Waste Conference, Purdue University, May 2-4, 1961.
178. Williams, S.W., and G.A. Hutto, "Treatment of Textile Mill Wastes
in Aerated Lagoons," Proc. 16th Ind. Waste Conf., Purdue University,
May 2-4, 1961.
179. Gramley, D.L., and M.S. Heath, "A Study of Water Pollution Control
in the Textile Industry of North Carolina," Water Resources Research
Institute of University of North Carolina.
180. Perera, N.A.P., "Textile Effluents and their Safe Disposal," Silk
and Rayon Industries of India, 12, 555-74, November 1969.
181. Stewart, R.G., "Pollution and the Wool Industry," Wool Research
Organization of N.Z., Report No. 10, 1971.
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182. Gcnapat, S. \t., "Some Observations on In-Plant Process Control for
Abatement of Pollution Load of Textile Wastes," Environmental Health,
(8) No. 3. 169-17?, 1966.
183. Veldsman, D.P., "Pollution Resulting from Textile Wastes," Wool
Grower, (23) No. 5, 27, 29, 1970.
184. Judkins, J.F., R.H. Dinius, et al., "Gamma Radiation of Textile
Wastewater to Reduce Pollution," Water Resources Research Inst.,
Auborn, University, Alabama.
185. Howard, M., "Textiles: Special Problems?" Water and Wastes Engineerin
March, 1973.
186. Poon, C.P.C., and E.L. Shunney, "Have a Space Problem,11 Water and
Wastes Engineering, March 1973.
187. "Pollutants are all burned Up," Water and Wastes Engineering,
March 1973.
188. "Clemson has Wastewater Breakthrough," Southern Textile News, 12,
October 18, 1971.
189. "Waste Treatment System at Foremost Recycles Hundred Percent of Water,
Mill Whistle, (29) No. 6, 2-3, 6, September 21, 1970.
190. Rebhun, M., A. Weinberg, and N. Narkis, "Treatment of Wastewater from
cotton Dyeing and Finishing Works for Reuse."
191. Petru, I.A., "Combined Treatment of Wool Scouring Wastes," J. Inst.
Sew. Purif., Paper No. 3, 497-9, 1964.
192. Kaukare, V.S., "Water conservation and its Reuse from Treated
Effluents," Textile Dyer and Printer (Ind.) (3) No. 1, 171-5, 1969.
193. "Treatment System Allows 100 Percent Recycling of Wastewater,11
Industrial Waste, (19) No. 2, IW/18-19, March/April, 1973.
194. Ingols, R.S., R. Roberts Jr., and E. Garper, and P. Vira, "A Study
Of Sludge Digestion with Sodium Chloride and Sulfate," PB196732,
Final Report Project No. B 338, under Res. Grant RG 17070, Fed. Water
Quality Admin., Dept. Interior, by Ga. Inst. Tech. Eng. Expt. Sta.,
Atlanta, Ga., September 1970.
195. Rayburn, J.A., "Examine Those Effluents," American Dyestuff Reporter,
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(61) Nc. 9, 103-4, 1972.
196. Cas°.r F.N., ^.E. Ketchen, and T.A. Alspaugh, MGamma-Induced Low
Temperature Oxidation of Textile Effluents," JAATCC, (5) No. 9, 1973.
197. Roop, N. , "Mothproofing Without Pollution," JAATCC, (5) No. 3, 1973.
198. Stovall, J., "The 1972 Water Pollution Control Act Amendments Ana-
lyzed," Modern Textiles, (54) No. 2, 14-16, 19, 23, 1973.
199. Little, A.H., "Measures Taken Against Water Pollution in the Textile
Industry of Great Britain," Pure and Applied Chemistry, 29, 1-3,
355-64, 1972.
200. Baddy, J.M., "Activated Sludge Treatment of Textile Wastes to Meet
High Stream Classifications - What standards and How to Meet Them,"
AATCC National Technical Conference, September 28-30, 1972.
201. Williams, H.E., "Treatment and Reuse of Screen Printing Dye Waste
waters," Paper presented at the 45th Annual Conference of the Water
Pollution Control Federation, October 8-13, 1972.
202. Alspaugh, T.A., "Treating Dye Wastewaters," Paper presented at the 45t
Annual Conference of the Water Pollution Control Federation, October
8-13, 1972.
203. Rayburn, J.A., "Overall Problems of Tertiary Treatment of Textile
Waste for the Removal of Color, COD, TOC, Suspended Solids,
Dissolved Solids, etc.," Paper presented at AATCC National Technical
Conference, Philadelphia, Pa., September 28-30, 1972.
204. "Color, Heavy Metal Removed by Adsorption," Chemical Processing, (35)
No. 9, 13, 1972.
205. "Water Usage in the Wet Processing of Wool Textiles," Wira Report 79.
206. Cosgrove, W.J., "Water Pollution and the Textile Industry," Canadian
Textile J., 63-6, January 1970.
207. Eguchi, Y., and Y. Uda, "Wastewater Treatment by Granular Activated
Carbon," J. Textile Machinery Soc. Japan, (24) No. 8, 555-61, 1971.
208. Jones, T.R., "Textile Industry Wastes: Effluent Treatment: Waste
Reclamation: Man-made Fibers," Effluent 6 Water Treatment Journal,
London, (12) No. 7, 352-355, July 1972.
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209. Simon-Hartley, "Treatment of Dyeing and Finishing Effluents from a
Textile Works," Intern. Dyer, (143) No. 51. 53-4, January 2, 1970.
210. Button, D.G., "Improved biological wastewater treatment," Du Pont
Innovation, (3) No. 1, 6-8, 1972. (Eng.)
211. Rhame, G.A., "Review of South Carolina Practices in Textile Finishing
Wastes," Industrial Waste, 18 Iw/49-53, September-October 1972.
212. "Textile Industry Wastes: Effluent Treatment: Water Reclamation:
Great Britain," Textile Res. Conference, Final Report, 73 pages.
213. corning, V., "Pollution Control in Jantzen Dyehouse," Knitting Times
(39) No. 35, 44-45, 1970.
214. "Textile Water Pollution Cleanup Picks Up Speed," Textile World,
54-66, November 1967.
215. Sahlie, R.S., and c.E. Steinmetz, "Pilot Wastewater Study Gives
Encouraging Indications," Modern Textiles, (50) No. 11, 20-28, 1969.
216. "Trade Effluent Control in the Carpet Industry," Textile Institute
and Industry, (3) No. 9, 237-40, 1965.
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SECTION XIV
GLOSSARY
acetate - A manufactured fiber made from cellulose acetate.
acid dye - A type of dye commonly used to color wool and nylon but may
be used on other fibers.
Acrilan - Trademark of Monsanto for acrylic fiber.
acrylic - A manufactured fiber in which the fiber-forming substance is
any long chain synthetic polymer composed of at least 85% by weight of
acrylonitrile units. Made in both filament and staple form. (See
Acrilan, Orion, Creslan.)
Arnel - Trademark (Celanese Corp.) for cellulose triacetate fiber.
Avicron - Trademark (FMC Corp.) for rayon filament yarn.
Avril - Trademark (FMC Corp.) for staple and filament rayon.
beck - A chamber in which goods may be scoured and dyed. May be operated
at atmospheric pressure or at elevated temperature and pressure.
biphenyl (or diphenyl) - A carrier used in dyeing polyester.
biochemical oxygen demand (BOD) - A method of measuring rate of oxygen
usage due to biological oxidation. A BOD5 of 1000 mg/liter means that
a sample (1 liter) used 1000 mg of oxygen in 5 days.
bleaching - Removal of colored components from a textile. Common bleaches
are hydrogen peroxide, sodium hypochlorite, and sodium chlorite.
blend - the combination of two or more types of fibers and/or colors in
one yarn.
bottom chrome - Term used in application of certain dyes to wool.
Involves use of chromium compounds.
butyl benzoate - A carrier used in dyeing polyester.
carded - Yarn in which fibers are separated and aligned in a thin web,
then condensed into a continuous, untwisted strand called a "sliver."
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carrier - An organic material used in dyeing polyester. (See biphenyl,
orthophenyl phenol, trichlorobenzene, butyl benzoate.)
cationic dye - The colored component of this type of dye bears a
positive charge.
caustic soda - A strong alkali used, for example, in mercerizing.
cellulose - Major component of cotton and rayon. Also used as the base
for acetate fiber.
chemical oxygen deman (COD) - The amount of oxygen required to oxidize
materials in a sample by means of a dichromate solution.
combed cotton - Cotton yarn that is cleaned after carding by wire
brushes (combs) and roller cards to remove all short fibers and
impurities.
crease-resistant - Fabrics that have been treated to make them resistant
to wrinkling. One of the most common methods is to incorporate a resin.
Creslan - Trademark owned by American Cyanamid Co. for acrylic fibers.
cross-dyed - Multicolored effects produced in one dye bath from fabrics
containing fibers with different affinities to the same dye.
Dacron - Trademark owned by Du Pont for polyester filaments and staple
fibers.
denier - Unit of weight indicating size of a fiber filament based on
weight in grams of a standard strand of 9000 meters.
desize - Removal of size. Several methods may be used. (See enzyme.)
developed dye - An azo dye whose color is developed by reaction on
cotton.
dichromate - A chemical used widely in applying some dyes. Also used
in boiler water. A toxic material.
fieldrin - Chemical applied to wool to eliminate damage due to moths.
Toxic.
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diphenyl - (See bir.jenyl).
direct dyes - Class o^ dyestuffs that colors cellulosic fibers in full
shades.
disperse dye - A type of dye used to color several synthetic fibers.
Applied as a fine dispersion using a carrier. On cloth, padded dye
may be baked on or "thermofixed."
dissolved solids - Total solids - suspended solids in a sample of
waste water.
dope-dyed - Trade slang for "solution dyed" or "spun dyed" meaning that
color is put into the chemical liquid from which synthetic fibers are
drawn. Filaments emerge colored.
double knit - Knitted fabric made on a special knitting machine that
combines a double set of needles to produce a fabric.
Durable Press - Goods that require no ironing during the normal use-
life of a garment. The term applies to apparel and other textile
products such as sheets, draperies, etc. A a rule, DP is achieved
in two ways: 1. Pre-curing fabrics with a special resin finish then
pressing made-up garment. 2. Post-curing fabric with a resin finish
then cooking made-up garments in an oven. As a rule, polyester-cotton
blends are used, but there are IOCS cottons, and other blends also.
enzyme - An agent used to remove starch size.
felt - A mat of fiber of wool often mixed with cotton or rayon.
flock - Short fibrous particles of fibers or short hairs applied by
various processes to the surface of a fabric.
fly - Waste fibers or particles which fly out into the air during
carding, drawing, spinning, or other fiber processing.
Fortrel - Trademark owned by Fiber Industries, Inc., for polyester
fiber.
greige - Fabrics in unbleached, undyed state before finishing. In
U.S., "gray goods" or "grey goods."
Herculon - Trademark owned by Hercules, Inc., for polypropylene fibers.
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jig-dyed - Dyed in open width on a machine called a "jig." Cloth moves
from one roll to another through the dye liquor until the desired
shade is obtained.
jute - Coarse, brown fiber from the stalk of a bast plant grown in
India. Used mainly for burlap, cordage, and as a backing for rugs
and carpets.
kier - A piece of equipment in which cotton is boiled with dilute
caustic soda to remove impurities. Also used as a verb to describe
the process.
knitting - Process of making fabric by interlocking series of loops
of one or more yarns. Types are: jersey (circular knits), tricots
(warp knits)t double knits.
Kodel - Trademark owned by Eastman Chemical Products Inc. for polyester
yarn and fiber.
Lycra - Trademark (Du Pont) for polyurethane multifilament elastic
yarn. The fused multifilaments in a bundle form a monofilament yarn
that stretches and snaps back.
mercerizing - Finish used on cotton yarns and fabrics to increase
luster, improve stretch and dyeability. Treatment consists of im-
pregnating fabrics with cold concentrated sodium hydroxide solution.
Mitin - Trademark owned by Geigy Co., Inc. for a moth-repellent finish
for woolens.
modacrylic - Generic name established by the Federal Trade Commission
for a "manufactured fiber in which the fiber-forming substance is any
long-chain synthetic polymer composed of less than 85% but at least
35% by weight of acrylonitrile units."
mordant - A metallic salt used for fixing dyes on fibers.
naphthol dye - A azo dye whose color is formed by coupling with a
naphthol. Used chiefly on cotton.
non-woven - A material made of fibers in a web or mat generally held
together by a bonding agent.
nylon - Generic name for "a manufactured fiber in which the fiber-
forming substance is any long-chain synthetic polyamide having recurring
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amide groups as an _ntegral part of the polymer chain."
Orion - Trademark (Du Pont) for acrylic fiber.
ortho phenyl phenol - A carrier used in dyeing polyester.
package dye - A method for dyeing many cones of yarn at once by
pumping a dye solution through the yarn.
permanent finish - Fabric treatments of various kinds to improve
glaze, hand, or performance of fabrics. These finishes are durable
to laundering.
pH scale - A method used to describe acidity or alkalinity. pH 7
is neutral; above 7 - alkaline; below 7 - acid. The scale extends
from 0 to 14 and a change of 1 unit represents a tenfold change in
acidity or alkalinity.
pigment prints - Made with insoluble pigment mixed with a binder and
thickener to form the printing paste.
pile fabric - Fabric with cut or uncut loops which stand up densely on
the surface.
polyamide - (See nylon.)
polyester - A manufactured fiber in which the fiber-forming substance
is any long-chain synthetic polymer composed of at least 85% by weight
of an ester of dihydric alcohol and terephthalic acid. (See Dacron,
Fortrel, Kodel.)
polypropylene - Basic fiber-forming substance for an olefin fiber.
precured fabric - Technique for imparting durable press by impregnating
fabrics with special resins then curing same. Does not require oven
after-treatment of apparel. (See durable press.)
Post-cured - Technique for imparting durable press that requires baking
apparel in ovens to cure fabrics that have been impregnated with special
resins. Most common technique used with polyester and cotton blends.
(See durable press.)
printing - Process of producing designs of one or more colors on a
fabric. There are several methods, such as roller, block* screen, etc.,
and several color techniques, such as direct, discharge, and resist.
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print paste - A mixture containing a dye or pigment used in printing.
Generally contain gums (thickener) and a solvent. (See also pigment
prints.)
raschel - Warp-knit, similar to tricot, but coarser. Made in a wide
variety of patterns.
rayon - A generic name for man-made fibers, monofilaments, and con-
tinuous filaments, made from regenerated cellulose. Fibers produced
by both viscose and cuprammonium process are classified as rayon.
reactive dyes - Dyes that react chemically with the fiber.
resin - A chemical finish used to impart a property desired in a fabric,
such as water repellency or hand, etc. (See durable press.)
resist dye - Method of treating yarn or cloth so that in dyeing the
treated parts do not absorb the dyestuff.
roller prints - Machine made, using engraved copper rollers, one for
each color in the pattern.
scouring - Removal of foreign components from textiles. Normal
scouring materials are alkalies (e.g., soda ash) or trisodium phos-
phate, frequently used in the presence of a surfactant. Textile
materials are sometimes scoured by use of a solvent.
screen prints - A screen of fine silk, nylon, polyester, or metal mesh
is employed. Certain areas of the screen are treated to take dye,
others to resist dye. A paste color is forced through the screen onto
the fabric by a "squeegee" to form the pattern.
sequestrant - A chemical used to bind foreign metal ions. Frequently
used in dyeing. A common sequestrant is EDTA.
size - A material applied to warp yarns to minimize abrasion during
weaving. Common sizes are starch, polyvinyl alcohol (PVOH), and
carbonxymethyl cellulose. Sizes are applied continuously in a slasher.
softener - A chemical used to apply a soft, pleasant hand. Fat
derivatives and polyethylene are common softeners.
solution-dyed - Synthetic fibers sometimes are dyed by adding color
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to the chc-nical polymer before fibers are formed. Also called dope
dyed.
standard raw waste load (SRWL) - A description of the properties of
waste water before treatment.
starch - Organic polymer material used as a size; highly biodegradeable.
sulfur dye - A class of dyes which dissolve in aqueous sodium sulfide
forming products with a marked affinity for cotton; the dyes are
regenerated by air oxidation.
suspended solids - Amount of solids separated by filtration of a
sample of waste water.
textured - Bulked yarns that have greater volume and surface interest
than conventional yarn of same fiber.
top chrome - Term used in application of certain dyes to wool. Involves
use of chromium compounds.
top-dyed - Wool which is dyed in the form of a loose rope of parallel
fibers prior to spinning fibers into yarn.
total organic content (TOC) - The total organic materials present in
a sample of waste water.
total oxygen demand (TOD) - The amount of oxygen necessary to completely
oxidize materials present in a sample of waste water.
total solids - Amount of residue obtained on evaporation of a sample
of waste water.
triacetate - Differs from regular cellulose acetate, which is a di-
acetate. The description implies the extent of acetylation and
degree of solubility in acetone.
tricot - Warp-knitted fabric. Tricots are flat knitted with fine ribs
on the face (lengthwise) and ribs on the back (widthwise).
tufted fabric - Fabric decorated with tufts of multiple ply yarns.
Usually hooked by needle into fabric structure. Used widely for carpets.
vat dye - A type of dye applied from a liquor containing alkali and a
powerful reducing agent, generally hydrosulfite. The dye is subsequently
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oxidized to the colored form. Widely used on cellulosic fibers.
warp - Set of lenthwise yarns in a loom through which the crosswise
filling yarns (weft) are interlaced. Sometimes called "ends."
weaving - The process of manufacturing fabric by interlacing a series
of warp yarns with filling yarns at right angles.
yarn - An assemblage of fibers or filaments, either manufactured or
natural, twisted or laid together so as to form a continuous strand
which can be used in weaving, knitting, or otherwise made into a
textile material.
yarn-dyed - Fabrics in which the yarn is dyed before weaving or
knitting.
VII 5.2H-5.28),;lines from 4000 to 5000
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