In-Plant
Control of
Pollution
Upgradinglextile Operations
to Reduce Pollution
^Technology Transfer Seminar Publication
-------
-------
EPA-625/3-74-004
IN-PLANT CONTROL OF POLLUTION
Upgrading Textile Operations
to Reduce Pollution
ENVIRONMENTAL PROTECTION AGENCY* Technology Transfer
October 1974
-------
ACKNOWLEDGMENTS
This seminar publication contains materials prepared for the
U.S. Environmental Protection Agency Technology Transfer Program
and presented at industrial pollution-control seminars for the textile
industry.
This publication was coordinated by the Institute of Textile
Technology, Charlottesville, Va., with the help of numerous people
in the textile industry as noted in each chapter or section.
NOTICE
The mention of trade names or commercial products in this publication is
for illustration purposes and does not constitute endorsement or recommenda-
tion for use by the U.S. Environmental Protection Agency.
-------
CONTENTS
Page
Introduction 1
Parti. Water-Pollution Abatement ...*... 3
Chapter I. The Waste Survey 5
Introduction 5
Preliminary Survey . 5
Detailed Survey . . 21
Data Evaluation 23
Continuing Monitoring 25
Chapter .II. Major Sources of Waste 27
Characteristics of Textile Waste Loads . 27
Chapter III. Flow Reduction 39
Case Histories 39
Chapter IV. Water Reuse .- . . . 41
Case Histories 43
Chapter V. Waste Segregation 45
Chapter VI. Panel Discussion on Substitution of Processes and Materials 47 •
General Considerations 47
What Can Chemical Substitution Produce in Pollution Reduction? 49
Size Substitution 59
Reduction of Wastewater Foaming by Process-Chemical Substitution 63
Chapter VII. Pretreatment of Textile Wastes 67
Introduction 67'
Sewerage-Treatment Systems 67
Potential Effect of Textile Wastes 68
Pretreatment Methods 70
References 78
Chapter VIII. Summary 81
The Waste Survey, Major Sources of Waste, and Flow Reduction 81
Water Reuse, Waste Segregation, and Substitution of Processes and Materials .... 83
Pretreatment of Textile Wastes 85
Part II. Air-Pollution Abatement 87
Chapter I. The Emissions Survey 89
References 90
m
-------
CONTENTS-Continued
Page
Part II. Air-Pollution Abatement (Continued)
Chapter II. Particulate Control 91
Source, Effect, and Analysis of the Particulate Emissions 91
Expected Effectiveness and Relative Cost of Various Methods of Abatement .... 91
Case Histories of Recently Installed Control Equipment .92
Chapter III. Solvent Processing and Recovery 95
Chapter IV. Summary 97
Survey and Analysis of Emission Problems 97
Sources 97
Abatement and Control Measures 98
Appendix A. Tables of Additional Data and Information Characterizing
Textile Process Wastes and Constituents
Appendix B. Tables Illustrating Relative Amounts Used and BOD Loadings of
Chemicals Consumed in Cotton Finishing and Comparison of Views on
Acceptable Criteria for Textile Process Water
101
113
IV
-------
INTRODUCTION'
The total process-water consumption of the textile industry in 1972 was about 125 billion
gallons per year. About 680 wet-process plants of the more than 7,000 plants in the United States
account for 95 percent of the water used. Only about 20 percent of the water was discharged un-
treated; the remainder underwent municipal or onsite secondary waste treatment. The textile
industry recognizes the necessity for close cooperation with the EPA if the national goals of water-
pollution abatement are to be realized. The need for upgrading existing wastewater treatment and
procedures to conform or to meet EPA guidelines and standards of performance applicable to the
textile industry may arise from one or more of the following reasons:
• Lack of proper plant operation and control
• Inadequate plant design
• Changes in wastewater flow or characteristics
• Changes in treatment requirements
There are many areas relating to air pollution that concern industries, including the textile
industry, but in this publication, the concern is confined to air pollution that arises from dyeing
and finishing operations. The Clean Air Act of 1963 and subsequent amendments, particularly those
of 1970, relate to the protection and enhancement of air quality in the United States. Both author-
ize and mandate the implementation of Federal programs and programs for State-Federal cooperation
designed to attain these objectives within strict time schedules.
The first part of this publication is concerned with water, and the second part is concerned
with air. The various areas under Water Pollution Abatement to be given consideration are (a) The
Waste Survey, (b) Major Sources of Waste, (c) Flow Reduction, (d) Water Reuse, (e) Waste Segrega-
tion, (f) a panel discussion on Substitution of Processes and Materials, and (g) Pretreatment of
Textile Wastes, whereas the areas to be included under Air Pollution Abatement, within the pre-
viously given limitations imposed, are (a) the Emissions Survey, (b) Particulate Control, and
(c) Solvent Recovery.
*Prepared by Jack Compton of the Institute of Textile Technology, Charlottesville, Va.
-------
-------
Part I
WATER-POLLUTION ABATEMENT
-------
-------
Chapter I
THE WASTE SURVEY'
INTRODUCTION
One of the first major steps in an industrial water pollution control program is to define the
scope of the abatement effort by determining the characteristics of the wastewater. This chapter
deals with the wastewater characterization or wastewater-survey segment of the pollution-control
program and also with a continuing survey to monitor changing characteristics and to aid in evalu-
ating production changes.
The waste-survey topic can be broken into the following four essentially chronological segments:
• Preliminary survey
• Detailed survey
• Data evaluation
• Continuing monitoring
PRELIMINARY SURVEY
The initial effort in a water-pollution-control program is typically a feasibility study that
attempts to answer the following questions:
• What will be the discharge criteria?
• What are the likely methods of treatment?
• What in-plant alternates are available for waste reduction?
The data base for this feasibility study is the information gathered from a preliminary waste survey.
The goals of this initial survey are to
• Determine the approximate volume of wastewater
• Determine the approximate wastewater characteristics
• Define the major waste sources and possible methods of in-plant waste reduction and control
• Define the approximate characteristics of the raw-water source and the receiving stream
*Prepared by T. L. Rinker of Blue Ridge-Winkler Textiles, Bangor, Pa.
-------
The purpose of the survey, therefore, is not to define the problem for the purposes of final
commitments, but only to obtain an accurate overview that will allow selection of the most likely
problem solutions from the many that are available. The duration and complexity of this work will
vary proportionally with the size and complexity of the mill and with the degree to which experi-
ence or the literature can provide direction or answers.
Any preliminary survey should consist of the following segments:
• Development of an approximate water and wastewater balance
• Wastewater sampling and analysis
• Review of manufacturing operations and raw material usage
• Flow measurement, sampling, and analysis of major waste sources
• Sampling and analysis of the raw water and receiving stream
Incoming-water information for the mill can be developed from any of the methods shown in
table 1-1. Ideally, there will be water meters installed on the major branches of the mill-distribution
system, but this is seldom the case, and an approximate breakdown of the water flow is usually
necessary. These water data should cover several 1-month periods in order to reflect various produc-
tion levels and product mixes. This water use should be broken down on a daily basis, and the
production level for each area recorded. The final result of this work will be a drawing such as that
shown in figure 1-1, which indicates the distribution system, the water usage in gallons per day, and
the water usage rate in gallons per pound of cloth.
Similarly, a detailed map should be developed showing the location of major sewer lines and
sources of wastewater. Process, sanitary, and storm water sources should be indicated, as should be
points of discharge.
Typically, most mills do not have an accurate drawing showing the locations of all sewer: lines
and waste sources, but it is important that this map be developed. Dye tracing should be used to
identify what happens to all known sources and to check for cross-connections between separate
sewer systems.
Table 1-1 .—Methods of flow measurement for incoming water and wastewater
Water
Incoming
Waste
Method
Daily water-meter readings
Monthly water bills
Records of pump running time
Estimation of capacity of water-use points
Discharge through an orifice
Discharge over a weir
Discharge through a flume
Salt injection
Dye or float timing
Timing of a container
Pump timing
Current meters
Venturi, orifice, or magnetic flow meters
Rotameter
-------
GALLONS PER DAY-GALLONS PER POUND
Minimum Average Maximum
Evaporation
Finishing room
Bleach range
Continuous range
Dye house
Chemical room
Air-pollution equipment
Sanitary
Utility cooling
Process cooling
Figure 1-1. Water-distribution system for a finishing plant.
Flow rates for sanitary and storm water sources can be estimated, but flow rates for the process
sewer or sewers should be determined by flow measurement. The method of flow measurement used
is dependent on the volume of water, the physical •restraints of the measurement point, and the accu-
racy required. Tables 1-1 and 1-2 and figure 1-2 show the various methods of measurement normally
used and the conditions under which they are appropriate.
For a preliminary study, flows should be measured onpe per hour over a 24-hour period 1 day
per week for 4 weeks. These data can then be compared with production and water-use data to
extrapolate to various production levels.
The final result of this work will be a drawing such as that shown in figure 1-3, which indicates
the sew,er system, the;flow in gallons per day from the major waste, sources, and the flow rate in gal-
lons per pound of cloth from the major waste sources.
,- , • • •:••! '• •• •••.•••;. , .- •....••. . - • ;••• •-; . / ' •.• -••' '•'•' "'•' "'•.' :'...-•
Simultaneous'with the flow measurement, sampling of the wastewater should be accomplished.
An automatic sampler station that will provide hourly samples is recommended. This equipment
should allow for either continuous or intermittent sampling so that each hour sample will be a com-
posite. Figure 1-4 shows various sampling equipment arrangements.
The test methods recommended by the EPA in.the June 29, 1973, Federal Register are sum-
marized in table 1-3. :
-------
Table \-2.-Comparison of flow-measurement techniques
Specific notes
Method
Orifice
Weir
Flume
Salt injection
Dye or float
Container
Pump
Current meters
Flow meters
Rotameter
Open end pipe
Flow range
Small
Small to large
Small to large
Small to medium
Small
Small
Small to large
Small to large
Small to large
Small to medium
Small to medium
Cost
Medium
Medium
High
Low
Low
Low
N/A
Medium
High
Medium
Low
Ease of
installation
Fair
Fair to difficult
Difficult
Fair
N/A
N/A
N/A
Fair
Difficult
Fair
Fair
Accuracy
Excellent
Good to excellent
Excellent
Good
Fair
Good
Fair
Fair
Excellent
Good
Fair
Application
Pipe and open channel
Open channel
Open channel i
Pipe and open channel
Open channel
Pipe and open channel
Pipe
Pipe and open channel
Pipe
Pipe
Open channel
General notes
Method
Note
Orifice
Weir
An orifice can be used to determine the flow from a vessel through a circular outlet by measuring
the height of water in the vessel.
A weir is used to determine flow by measuring the difference in elevation between the discharge
edge (crest) and the upstream water level.
Weirs are simple, reliable measurement devices when they are installed correctly. Accuracy is ±5
percent.
The weir crest must be sharp
Air must have access to the underside of the falling water
Leaks must be sealed
Weir must be exactly level
Weir approach must be kept clean of sediment
The head should be measured back of the crest at least five times the height
The upstream channel should be reasonably free from disturbances
A weir measurement should consist of the average of several equally timed readings
There is more head generated on a V-notch weir; therefore, these weirs are used for smaller flows
in order to maintain accuracy.
Automated level recorders (pressure or mechanical) should be used for permanent installations or
deep sewers.
A Parshall flume is a permanent installation that measures the difference in water levels caused by
a constriction in the channel cross section.
The advantages of dependable accuracy, low head loss, and large capacity range are offset by the
high installation costs. The flumes can be purchased as a complete package with flow recording
equipment.
An accuracy of ±5 percent is obtained when the equipment is installed properly.
• Standard dimensions must be used
• The downstream head should not exceed the recommended percentage of upstream head
• The upstream head is measured in a stilling well
• The flume is installed in a straight channel, and there is no close upstream turbulence
8
-------
Table I-2.-Comparison of flow-measurement techniques.—Concluded
General notes
Method
Note
Salt injection
Floats
Container
Pump
Current meters
Flow meters
Rotameters
Open-end pipe
The salt injection method depends on determining the downstream concentration of a readily
detectable chemical (e.g., lithium chloride) when a known quantity of the material is injected
upstream. The method is useful when
• The physical location of the sewer (e^g., depth) makes weir measurement impossible
• Waste is flowing under pressure
• When accurate total flow values are required, and mechanical or frequent manual weir height
measurement is not feasible
• When a simultaneous sampling program is being conducted
This method requires the measurement of water depths and velocity and should only be used for
approximations of flow.
This method requires measuring the time for a discharge to fill a vessel of known volume and is
good only for small flows.
This method requires timing the amount of time a pumping is running and determining the water
Volume from the pump characteristics. ;lt should only be used for approximations of flow.
This method requires determining the cross sectional area of a channel and measuring the water
velocity in several segments. The method is used for measuring small stream flows.
Flow meters measure water flow in pressure systems by detecting differential pressure across a
contraction (e.g., Venturi tube or orifice plate) or by detecting the electrical potential produced
by the flow. This equipment is accurate and reliable over a wide range of flows but is an expensive,
permanent installation.
These meters measure water flow by the water turning a set of gears to totalize flow or by suspend-
ing a float to indicate instantaneous float. The equipment will vary widely in cost depending on
size and accuracy requirements.
This method requires the measurement of vertical fall of a free-flowing discharge from a pipe and
should only be used when other methods are not practicable.
At the end of a 4-hour period, the hourly samples should be chemically preserved and refrig-
erated unless analyzed immediately. Table 1-4 shows the preservation procedures recommended by
the EPA. The EPA Methods of Chemical Analysis of Water and Wastes is recommended as the pro-
cedural standard. Figure 1-5 shows the results of a flow and sampling survey.
The analytical schedule for the process sewer samples is dictated by the discharge criteria and by
a knowledge of manufacturing chemicals. EPA and the States require the filing of a permit applica-
tion for obtaining a discharge permit under the 1972 amendments. This application requires infor-
mation on some 60 parameters. In order to limit the extent of the analysis program, it is recom-
mended that the schedule shown in table 1-5 be used for the preliminary survey.
The work discussed above is to develop the information necessary for final treatment of the
wastes. Of equal importance is the in-plant analysis to define major sources and possible methods of
waste reduction and/or segregation. This work is started by developing (1) a material balance for
each major production unit and (2) a history of chemical and dyestuff usage.
9
-------
C = 0.632
C = 0.966
= cA,72gH
A. ORIFICE
Q = discharge, ft3/s
c = constant
A = orifice area, ft2
V = velocity, ft/s
g = acceleration due to gravity,
ft/s2 = 32.2
H = head, ft
a = 671/2 45 22V4
c = 0.684 0.753 10.882
2.5H
2.5L
n—i
i irf ^1
L-
V
90 V Notch"
L.l-.', ' ""
Q=2.52H2.47
Rectangu far Wetr
Q - 3.33-LH1-5
Q = dischargehft3/s
H = head, ft
B. WEIRS
Q,= discharge, ft3/s
H = head/ft r ''
L = length of weir, ft
1." H <; 1/3 L' ".' . .
2. 0.5< H <;'2.0
3. "approach velocity less than 1 ft/s
C. PARSHALL FLUME
Q = 4WHn
Q = discharge ft3/s
W = thrcrat width, ft
H"='head, ft "s '
n = 1.522W0'026 '
Figure I-2. Formulas for flow measurement by various devices.
10
-------
D. FLOATS
Q = A'k (D/T)
Q = discharge, ft3/s
A' = area and welted sewer, ft2
D = distance between manholes, ft
T = average time, s
K= 0.8 for floats and 1.0 for dyes
Metering pump
Chemical drum
Sampling pump
Sample receivers
Manhole 1
Manhole 2
Q = Qt (Ct - C)
C
E. CHEMICAL TRACERS
Q = discharge, ft3/s
Qt = discharge of traces
C = concentration of tracer
in water after injection
Ct = concentration of tracer
being injected
F. END OF PIPE
Q =
1800 AX
Q = discharge, gal/min
A = area, ft2
Y = distance from water level
in pipe to water level
in stream at X, ft.
Figure I-2. Formulas for flow measurement by various devices.—Concluded
11
-------
Storm water
Cooling
Evaporation
Finishing room
Bleach range
Continuous range
Dye house
Chemical room
Air-pollution
equipment
Sanitary
GALLONS PER DAY-GALLONS PER POUND
Minimum Average Maximum
©
(e)
©
o
n
Figure 1-3. Sewer-system schematic for waste survey.
The intent of the material balance is to indicate both the fabric and chemicals going into and
out of a production unit. It is typical that the concentration of the chemicals coming from a pro-
duction unit cannot be readily determined. Therefore, at least the wastewater characteristics should
be indicated. The vendors of chemicals used in the mill can be of help in determining effluent con-
centrations of their materials. Examples of this work are shown in figures 1-6 and 1-7 and table 1-6.
The material balance analysis also serves as a check on process efficiency and may indicate potential
cost-saving changes.
The intent of the analysis of chemical and dyestuff usage is to approximate the chemical nature
of the wastewater. As in the case of the water balance, at this stage only one or two representative
months need to be examined. The form of this analysis can be as that shown in table 1-7 and will
indicate the importance of various chemicals to the treatment system. As part of the in-plant
sampling and analysis program, an analysis of the wastewater characteristics of the major chemicals
at various concentrations may be made. The data, when combined with a knowledge of the con-
centration in the effluent, will help to evaluate the treatment alternatives.
12
-------
Types of Samples !
• Grab: A single, manually collected sample
• Continuous: A single sample or a series of samples taken over a period of time by either
— A continuous small volume of flow
— An intermittent small volume of flow
— An intermittent small "Cut" of a larger volume of flow
• Composited: A single sample made up of ,
flow-proportional amounts of several
individual samples. The sample may be either
a grab or a continuous composite.
u
A. Portable, self-contained sampling unit,
variable speed, on/off flow, single composite
B. Same as "A" but with hourly compositor
UJU
C. Multiple-head, variable-speed pump with on/off flow for semipermanent installation
D. Self-contained sampling unit with refrigera-
tion unit
Figure 1-4. Seven typical methods of sampling wastes.
13
-------
n
F. Mechanical sampler with pump to obtain
a "split" or "cut" sampler
G. Permanent flow and sample station consisting of a flow recorder,
transmitter, variable-speed pump, and pump timer mounted over a
Parshall Flume
General notes:
• The sample point should be at approximately one-third of the water depth for sewers and channels
• Sampling point should not be adjacent to turbulent area, but flow should be mixed to insure repre-
sentative sampling, particularly of solids :
• Tube size and sample velocity should be considered to insure proper handling of solids
• Flow variations can normally be adequately covered with a sampling frequency of 10-15 minutes
unless the variations are very large
• For suction lifts of greater than 12 feet, submersible pumps should be used
• Sample containers should be glass or nalgene and adequately washed after being emptied
• For winter sampling, tubing should be placed in heat-traced pipes and sampler placed in a box with a
heat lamp or heat pad
Figure I-4. Seven typical methods of sampling wastes.—Concluded.
14
-------
Table 1-3.—Test methods recommended by the EPA
Measurement
Reference1
Alkalinity
Ammonia nitrogen
Arsenic ;
Boron
Cadmium
Chloride
Chromium
Conductance specific
Copper
Fluoride
Hardness
Iron
Magnesium
Manganese
Mercury
Nitrate nitrogen
Nitrogen, total Kjeldahl
Organic carbon, total
Organochlorine pesticides
Orthophosphate
Oxygen demand, biochemical
Oxygen demand, chemical
Phosphorus, total
Selenium
Silver
Solids, total
Surfactants
Suspended nonfilterable solids, total
Temperature
Zinc
C, p. 6
C, p. 134
A, p. 65, 4A (digestion) A, p. 62, method 104A (measurement)
A, p. 69
C, p. 83
B, p. 21, rnethod A
C, p. 83
B, p. 162, method B
C, p. 83
A, p. 171, rnethod 121A with p. 174, method 121C
A, p. 179, method 122A
C, p. 83
C, p. 83
C, p. 83
D
A, p. 458, method 213B
A, p. 4.69, method 216
C, p. 221
D, Appendix A, Part H
C,p. 243
A,,p. 489, rnethod 219
A, p. 495, method 220
C,p. 242
A) p. 296, method 150A
C, p. 83
A,,p. 535, method 224A
A, p. 559, method 229
A, p. 537, method 224C
A, p. 559, method 162 .
C,p. 83
1 "A" refers to Standard Methods for the Examination of Water and Wastewater, 13th edition, 1971. This publication is avail-
able from the American Public Health Association, 1015 18th St., NW., Washington, D.C. 20036.
"B" refers to the Annual Book of Standards, Part 23, Water; Atmospheric Analysis, 1972. This publication is available from the
American Society for Testing and Materials, 1916 Race St., Philadelphia, Pa. 19103. . \
"C" refers to Methods for Chemical Analysis of Water and Wastes, Environmental Protection Agency, Analytical Quality Con-
trol Laboratory', Cincinnati, Ohio. This publication is available from the Superintendent of Documents, U.S. Government Printing
Office, WashingtoVi, D.C. 20402 (Stock rto. 5501 -0067). ;
"D" refers to National Pollutant Discharge Elimination, appendix A, Federal Register, 38, No. 75, pt. II. ,
-------
Table 1-4.—-Sample preservation requirements for various parameters
Parameter
Preservative
Maximum
holding
period
Acidity-alkalinity
Biochemical oxygen demand (BOD)
Calcium
Chemical oxygen demand (COD)
Chloride
Color
Cyanide
Dissolved oxygen
Fluoride
Hardness
Metals, total
Metals, dissolved
Nitrogen, ammonia
Nitrogen, Kjeldahl
Nitrogen, nitrate-nitrite
Oil and grease
Organic carbon
PH
Phenol ics
Solids
Specific conductance
Sulfate
Sulfide
Threshold odor
Turbidity
Refrigeration at 4°C
Refrigeration at 4°C
None required
2 ml H2S04 per liter
None required
Refrigeration at 4°C
NaOH to pH 10
Determine on site
None required
None required
5 ml HNO3 per liter
Filtrate: 3 ml 1:1 HNO3 per liter
40 mg HgCI2 per liter-4°C
40 mg HgCI2 per liter—4°C
40 mg HgCI2 per liter-4°C
2 ml H2SO4 per liter-4°C
2 ml H2SO4 per liter (pH 2)
Determine on site
1.0 g CuSO4 /1 + H3 PO4 to pH 4.0 - 4°C
None available
None required
Refrigeration at 4°C
2 ml Zn acetate per liter
Refrigeration at 4°C
None available
24 hours
6 hours
7 days
7 days
7 days
24 hours
24 hours
No holding
7 days
7 days
6 months
6 months
7 days
Unstable
7 days
24 hours
7 days
No holding
24 hours
7 days
7 days
7 days
7 days
24 hours
7 days
Source: Methods for Chemical Analysis of Water and Wastes, EPA, 1971.
01
d
O
CD
I I I I
J I
Hours Hours
Figure 1-5. Typical preliminary survey results of BOD and flow measurements as a function of time.
16
-------
Table ^.—Preliminary survey analytical requirements on samples collected
First set of samples
Time of measurement
Item measured
Time-of-flow measurement
Hourly
24-hour composite
Dissolved oxygen
Temperature
BOD
COD
Suspended solids
pH
Color
Alkalinity
Dissolved solids
Various forms of nitrogen
Phosphorus
Turbidity
Various forms of sulfur
Halogens
Cyanide
Phenol
Surfactants
Aluminum
Arsenic
Cadmium
Calcium
Chlorinated hydrocarbons
Coliform bacteria
Cobalt
Chromium
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Potassium
Zinc
Second, third, and fourth set of samples
Instantaneous and hourly
24-hour composite
Same as first set
Dissolved solids
Forms of nitrogen (p>0.1)
Phosphorus
Turbidity
Forms of sulfur (p>0.1)
Halogens found (p>0.1),
Cyanide (p>0.01)
Phenol
Surfactants
Aluminum (/o>1.0)
Arsenic (p>0.01)
Cadmium (p>0.01)
17
-------
Table \-5.-Preliminary survey analytical requirements on samples collected.—Concluded
Second, third, and fourth set of samples
Time of measurement
Item measured
24-hour composite—Continued
Calcium (p>10)
Cobalt (p>0.01)
Chromium
Copper
Iron
Chlorinated hydrocarbons (p>0.01)
Coliform bacteria (p>1000)
Lead (p>0.01)
Magnesium (p>10)
Manganese (p>1)
Mercury (p>0.001)
Nickel (p>0.001)
Potassium (p>10)
Zinc
Note.-Tf
than 0.01 mg/l.
F
le shorthand
Dye mi>
Water
abric »
PH
BOD
COD
Color
Flow
(p>0.01) im
t
Dye pad
i
Dye pad
Jicates that further a
Finish
lalysis is necessary only if the first analysis indicates a value greater
en ix
— : i1" ' i
« t '
Washer
Finish pad
i i
Washer Finish pad
Frame
•
Equipment
wash
, • *., .,' . ,
',- ' • -J-C- ' -. •'
Dye formulas
.-Finish formulas
Products
Product rate
Miscellaneous chemicals
Figure 1-6. Dye-range material balance.
18
-------
!
i
i
".r
Mercerizer
t-ao
• Cat
. WE
1
ric
istic s
rter
1
Washer
No
\
. 1
oda
'
No
\
. <
. 2
\ 1
No. 3
r \
r
No. 4
'
No
i
1 '
.5
'
No. 6
i i
Alkalinity
Fabric
Waste
Fabric production rate:
Total water use:
Total caustic use:
Concentration:
Figure I-7. Mercerizer and washer material balance.
Table I -6.—List of important items for textile in-plant surveys
Identification of print paste, grease, and solvent wastes, for segregation to separate treatment
Identification of sources of chemicals potentially toxic to activated sludge systems (such as dyes, solvents, carriers, or
finishes)
Identification of sources of shock loaSs (such as finishing bath dumps)
Identification of sources of high concentrations of refractory, nonbiodegradable wastes (such as carriers and finishes)
Identification of sources of foam-producing chemicals (such as detergents)
Evaluation of size substitutions
Optimization of countercurrent washes
Evaluation of reuse of weak rinse wastes
Evaluation of segregation of high strength (such as BOD, COD, color, or alkalinity) for separate treatment
Evaluation of processing of caustic wastes for reuse
Evaluation of segregation of dyestuffs (acid, disperse, etc.) for separate treatment
Comparison of hypochlorite and hydrogen peroxide bleaching
19
-------
Table 1-7.—Example of annual chemical usage, 1972
Rank
1
2
3
4
5
6
7
8
g
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Chemical (type)1
Carrier NT (B)
Neutrol #9 (C)
Aerotex water repellant 95 (D)
Cap LEV LSP (C)
Soap OFF 60 (A)
Acetic acid (E)
IMeoport APO (B)
Solvecrest RB (A)
Monosodium phosphate (E)
Caustic soda (E)
Dispersing agent (C)
Avitone F (C)
Calgon (F)
Fanapon X70 (A)
Neoport DPG (B)
Raycofix NY (H)
Sanopan DTC (A)
Formic acid (E)
Sodium hydrosulfite (A)
Cap Carrier BB (B)
Ammonium chloride (E)
Herriton SWD (C)
Intrawite EBF (G)
Gluconic acid (C)
Tanalube RF (C)
Usage
Pounds
331,457
200,064
136,205
132,685
126,708
124,206
117,609
110,788
92,672
89,673
84,887
72,443
69,130
58,198
51,871
48,428
47,227
46,779
45,983
38,867
38,189
36,698
30,242
27,416
24,654
Percent
12.540
7.569
5.153
5.020
4.794
4.699
4.449
4.191
3.506
3.393
3.212
2.741
2.615.
2.202
1.962
1.832
1.787
1.770
1.740
1.470
1.445
1.388
1.144
1.037
0.933
A = scour; B = carrier; C = dyeing assistant; D = finish; E = pH control chemicals; F = softener; G = fluorescent; H = fixing.
For in-plant sampling, the use of appropriately chosen grab samples is usually sufficient. These
samples should be taken during each part of the production cycle, and an estimate or measurement
of flow made. Important wastewater characteristics should be measured in each sample, but it is not
necessary to perform a full analysis of each sample.
Also, on the day that the process sewers are sampled, a single grab sample should be obtained
from the receiving stream and the raw waste for complete analysis.
It should be apparent at this point in the review of the waste survey requirements that there is a
significant analytical load to any meaningful survey and that there is a strong emphasis on in-plant
production analysis.
Considering the degree of treatment being required of the textile industry, an important key to
compliance will be a competent water-quality laboratory to provide both operating and reporting
data. If a plant does not have sufficient facilities or staff for this work, then serious thought should
be given to acquiring the capability in this early stage to assure maximum familiarity with the waste-
water problem. This decision can usually be economically justified in light of outside laboratory costs.
20
-------
Also, the importance of introducing responsible production personnel at the onset of the water -
pollution-control program cannot be understated. This becomes even more important as regulations
require consistent removal of virtually all pollutants from the discharge. Soliciting process informa-
tion and keeping the production personnel informed of the work under way is the best way to
develop a program of optimum waste reduction and recycling and to determine how the waste is
affected by the operating characteristics of the process and its susceptibility to upset, misoperation,
and change.
DETAILED SURVEY
After completion of the initial feasibility study, a decision will probably be made to evaluate,
over a period of time, the treatment processes and in-plant control measures selected as the most
likely solutions. This additional detailed process evaluation study is necessary to firmly establish the
process design parameters and should also be utilized to gather additional waste characterization and
in-plant data.
Ideally, this final survey program should last 1 year in order to observe seasonal variations and
production vagaries and to allow time to fully develop and explore alternatives. The elements of this
detailed survey are essentially the same as the initial survey, but the intensity, duration, and pre-
cision of the various aspects have increased.
The incoming water balance information should continue to be recorded. Water meters will
allow for daily measurements. These data should be reported both as gallons per day and gallons per
pound of cloth. Similarly, refinement of the sewer balance should be undertaken.
At least one permanent flow measurement station should be built to continuously record total
plant effluent volume on a daily basis. This equipment should provide a 24-hour graph of flow. If
the wastewater volume can justify the expense, multiple stations should be installed to measure flow
from each department or division. An example of station locations is shown in figure 1-8.
As part of this station, a permanent sampling station should be installed to provide a single
daily-flow composited sample. Periodically, this composite can be removed once every hour to eval-
uate variations in waste strength.
A program of daily analysis of the process sewer waste should be instituted. This program should
attempt to frequently monitor critical wastewater characteristics and to regularly measure all neces-
sary characteristics. A recommended analytical schedule is presented in table 1-8.
Both flow and contaminant data should be reviewed frequently to determine trends and to
change the direction of the work as required.
Production data should also be recorded during this period. A history of chemical and dyestuff
usage should be maintained on a monthly basis. A history of production volume by major product
lines should be maintained on a weekly or daily basis. Changes in production chemicals or processes
should be noted.
Sampling and analysis of both raw water and receiving-stream water should continue once every
2-4 weeks. Raw-water samples should be taken on days when complete sewer analyses are scheduled.
If possible, any planned segregation of sewers should be accomplished during the study to make
sure that valid data:are obtained. Frequently, paper "substations" are not duplicated in the field
because complete segregation is not always possible.
21
-------
T3
C
o
• Q.
.
CD
D.
WS
_0
75
(3
Days
.n
as
c
•s
•a
O
a.
.
CD
Q.
Percent below
Percent below
Figure 1-9 Graphical results of detailed survey.
The data collected should also be interpreted in terms of the production processes and chemi-
cals used, and separate evaluations should be made, when possible, for the various periods.
The final step in the data evaluation segment is to correlate the information on present opera-
tion with the estimated capacity of the present or future manufacturing facility. The more pro-
duction segments that can be used to compile the estimate, the better the validity of the design basis.
24
-------
CONTINUING MONITORING
In addition to providing the basis for a rational wastewater-treatment-system design, the infor-
mation collected during the detailed survey will serve as a standard in monitoring the treatment
, facility for operational purposes and in comparing alternate production methods and.chemicals.
The importance of involvement of production personnel is strongly emphasized. Each super-
visor should be aware of his department's portion of
• The pollutants in pounds per pound of product
• The flow in pounds per pound of product
• The treatment cost in pounds per pound of product
• The environmental effect of production upsets
• The environmental impact of major production chemicals
Since textile mills are users of a wide variety of chemicals and since product lines regularly
change, there is a continual change in the chemicals found in the sewer. It is imperative that in addi-
tion to production characteristics, the environmental characteristics be considered in evaluating a
new chemical. During the detailed survey, the pollution potential was determined for important
chemicals. In the continuing survey, these characteristics are recorded for all chemicals. Also in the
detailed survey, brief treatability studies on the major chemicals may have been done; this work
should be continued. An example of the data that might be collected is given in figure 1-10. This
information will serve as a standard for comparing alternate chemicals.
Any preliminary survey is incomplete without an analysis of the impact of the discharge on the
receiving stream. First, stream flow records should be obtained from the U.S. Geological Survey in
order to develop critical flow values for various periods during the year. Second, information on
quantity and location should be gathered on users of and dischargers to the receiving stream. Third,
the receiving water should be completely analyzed, with single, representative grab samples of water
above the discharge obtained when the process sewers are sampled. Finally, a single sample of
bottom deposit above the discharge should be obtained for examination for basic indicator orga-
nisms and for chemical analysis. This later work will indicate the present condition of the stream and
its tolerance to additional pollutants.
The advent of industrial discharge criteria would seem to obviate the need for consideration of
the effect on the receiving stream, but it should be remembered that many States have or are devel-
oping stream criteria that may be more stringent than the Federal guidelines. This is especially
important when the discharge is to a stream rather than a large river.
;
In addition to the upstream sampling and analysis of receiving stream water, a profile of the
receiving stream at various stages below the discharge should be examined. This profile should con-
sist of both chemical and biological analysis of the water and the sediment and will serve as a base-
line of the stream's condition against which the new charge can be compared. A single bioassay and
multiple chemical assays will be necessary for accurate results. Also, static toxicity studies using
local species of fish and expected effluent should be performed to determine maximum allowable
pollutant concentrations and to verify design discharge criteria.
Finally, the continuing survey should monitor individual processes to make sure that unneces-
sary amounts of water and chemicals are not being used. That is, environmental impact should be-
come a tangible part of the industrial engineering function of process optimization.
25
-------
COD (TOG) of 1.0 % solution:
1
a
o
o
+-»
g
Jjjj
it
LU
Concentration of chemical
COD removal by
activated sludge
atMLSSof 3,000 mg/1
COD removal by
coagulation with
400 mg/1 alum
o
g
Q
O
O
c
0>
LU
Concentration of chemical
COD removal by
carbon adsorption
with 3.0 lb/1,000 gal
Figure 1-10. Typical data for determining treatability of process chemicals.
26
-------
Chapter II
MAJOR SOURCES OF WASTE*
The major sources of waste from textile operations include process effluents, which can first be
related to the following eight categories of textile wastes chosen by the EPA:
• Wool scouring
• Wool finishing
• Greige goods mills
• Woven fabric finishing ' .
• Knit fabric finishing ;
• Carpet mills
• Stock and yarn dyeing and finishing
• Specialized finishing
Obviously, this system of classification does little to indicate specifically where the chief sources of
water pollution within the industry are located. However, this classification system does function to
isolate wool scouring as the area with the highest raw waste discharge concentrations in terms of
5-day BOD (BODS).
It should be pointed out that generalizations for characterizing wastes within the industry can
often have little specific relevance. The reason for this is that textile wastes are extremely diverse.
The great variety of dyes, chemicals, and materials removed from textile fibers result in a complex
waste mixture that varies in composition from minute to minute depending on the unit processes
and operations. Such equipment can be batch types and/or continuous types. This means that at
any one sampling, one must consider the chemicals used, the fibers processed, the fabric weight, the
processing performed, the equipment used, and the arrangement of the equipment. Furthermore,
seasonal variations occur because many plants work on materials that are ordered at certain seasons,
such as rain wear or fashion prints.
In the description of major waste loads that follows, consideration is given to the range of
compositions that might occur and that has to be interpreted with a knowledge of the conditions
at any individual plant.
CHARACTERISTICS OF TEXTILE WASTE LOADS
Masselli and Burford1 first classified textile pollution sources on the basis of predominant
fiber. They surveyed wastes from cotton, wool, and synthetic-fiber processing. Results from their
studies showed that pollution loads originated from two sources: natural fiber impurities and
*Prepared by Michael S. Bahorsky of the Institute of Textile Technology, Charlottesville, Va.
27
-------
process chemicals. Grease scouring woolen mills contributed 50 percent of the total BOD load from
natural impurities. In all other plants, natural impurities contributed less than 30 percent of the
total BOD load. It is apparent from their studies that process chemicals contribute the greatest
pollution load from textile mills.
The data in table II-l give a comparison of expected waste loads from natural impurities of
various fibers with those from process chemicals used. It is obvious that very little can be done to
improve the waste contribution from natural impurities, but the range of BOD contribution from
the process chemicals indicates that chemical substitutions might improve at least the BOD picture
significantly for someone on the upper extreme of the range.
Little2 provided an interesting example from a cotton bleachery, which gives some idea of the
magnitude of the disposal problem. About 4-7 percent of the weight of cotton fabric can be
scoured from the fiber. About 4-6 percent more comes from the warp starch size that is removed.
This gives about 10 percent of the weight of the fabric to contaminate waste liquors. A bleach works
handling 1,000 tons of fabric a year would have to deal, therefore, with 100 tons a year—2 tons a
week—of waste organic matter.
An approach used in a report series issued by the FWPCA (now EPA) in September 1967, en-
titled "The Cost of Clean Water," gives a more specific breakdown of pollution load contributions
(see tables II-2, II-3, and II-4). (It should be noted that in this report, as in various other survey
reports, much information presented is taken from the series of reports prepared by Masselli and
Burford.)
The data presented in table II-2 are based on the estimate that the average production of. wool
scouring and finishing mills is 3,000 pounds per day of finished wool cloth. The daily waste con-
tribution by process for a cotton plant producing 20,000 pounds of cloth per day is shown in table
II-3. Again, it is emphasized that a specific plant on a particular day could deviate widely from the
figures shown. Table II-4 provides ranges of quantities of pollutants produced from a plant arbi-
trarily producing 10,000 pounds per day of manmade fiber cloth.
The area of manmade fiber waste characterization is probably the most complex to provide with
a typical example, since many manmade fibers are often blended with cotton and wool. In table II-4,
Table 11-1.—!Anticipated waste load ranges from processing various fibers (pounds BOD per 1,000 pounds cloth)
Fiber
Cotton
Greasy wool
Scoured wool
Rayon
Acetate
Orion
Nylon
Dacron
"Natural"
impurities
30-50
200-300
10-20
3-7
3-7
3-7
3-7
3-7
Sizes, oils,
antistats
5-100
2-90
2-90
5-60
5-60
5-60
5-60
5-60
Scouring
5-60
1 15-1 50
1 10-1 50
5-50
5-50
5-50
5-50
5-50
Dyes,
emulsifiers,
carriers, etc.
2-80
5-100
5-100
2-50
2-50
5-100
2-50
30-600
Special
finishes,
waterproof, etc.
2-80
2-80
2-80
2-80
2-80
2-80
2-80
2-80
Total
44-370
2 21 9-720
29-440
17-247
17-247
20-297
17-247
45-787
1High value includes soap used for fulling also.
2lf grease and suint are removed by solvent extraction, this load may be reduced by approximately 200 pounds.
Source: Masselli and Burford, "Pollution Sources from Finishing of Synthetic Fibers," 1956.
28
-------
Table 11-2.—Daily waste quantities from wool processing
[3,000 pounds per day production]
Process
Scouring
Dyeing
Washing
Carbonizing
Total
BQn,,ppunds
680
31
198
6.2
915.2
Gallons
6,200
9,300
130,000
49,600
195,000
Table 11-3.—Daily waste quantities from cotton processing1
Process
Desizing
Scouring
Bleaching
Mercerizing
Dyeing
Printing
Total
Approximate
percentage of
cloth treated
! 95
, 100
100
35
50
14
Wasteload, Ib/day for plant
producing 20,000 Ib/day
BOD
1,100
1,050
150
50
600
150
3,100
SS2
570
431
100
15
250
34
1,400
TDS3
1,000
1,300
700
200
700
200
4,100
Wastewater
0.05
0.09
0.09
0.08
0.40
0.04
0.75
ll\lote that the wastewater volume contributed by the dyeing operation is 52 percent of the total wastewater volume.
2SS indicates suspended solids.
3TDS indicates total dissolved solids.
Table I \-4.—Daily waste quantities from manmade fiber processing
Process
Scour Nylon
Scour and dye
Dye
Salt bath
Final scour
Special
finishing
(optional)
Total
Fiber
Nylon
Acrylic
Polyester
Rayon
Acetate
Nylon
Acrylic
Polyester
Rayon
Acrylic
Polyester
Rayon
Acetate
Nylon
Acrylic
Polyester
Rayon
Acetate
Nylon
Acrylic
Polyester
Thousand gallons
60-80
60-80
30-50
20-40
40-60
20-40
20-40
20-40
5-15
80-100
20-40
5-15
30-50
40-60
50-70
10-30
30-70
70-1 10
120-180
210-290
80-160
BOD, pounds
300-380
450-900
100-200
480-730
410-590
70-130
20-400
230-1 ,380
0-30
120-250
150-250
20-800
20-800
20-800
20-800
20-800
140-2,400
140-2,400
140-2,400
170-2,900
420-7,800
SS, pounds
200-400
250-500
50-150
0-30
-
10-200
20-420
50-200
-
20-60
30-70
30-1,000
30-1 ,000
30-1,000
30-1,000
30-1 ,000
200-3,000
200-3,000
200-3,000
250-4,000
300-6,000
TDS, pounds
300-500
1 20-200
250-350
250-390
-
200-340
60-90
300-2,000
200-2,000
40-120
100-500
30-1,000
30-1,000
30-1,000
30-1,000
30-1,000
200-3,000
200-3,000
200-3,000
250-4,000
300-6,000
29
-------
a high BOD is indicated for polyester dyeing. This is because of the contribution from high-BOD
carrier compounds. The BOD5 of various polyester dyeing carriers is shown in table II-5.
The data in tables 11-6,11-7, and II-8 are similar to the preceding data but are somewhat more
detailed. These tables are included because they are condensations of various studies that have
appeared over the years. Wide variations from values appearing in some instances support the fact
that although the tables indicate trends, they often will not correspond with individual analyses. (To
further guide in the understanding of where major waste loads occur within the textile industry,
tables A-l to A-12 in appendix A include information taken from the literature.)
To obtain an even more precise understanding of the waste loads contributed by a process, as
well as how the same process might differ in wasteload, tables H-9 and 11-10 -are provided. The data
in table II-9 show that when starch-sized cotton goods are desized by an enzyme, everything that
goes onto the goods comes off, and more. In this case, natural impurities, as suspended solids, con-
tribute to the final BOD output.
If, instead of using starch sizing, polyvinyl alcohol is used, then BOD output is reduced 95 per-
cent (table H-10). It is most important to note in this illustration that the price paid in reducing
BOD output is reflected in increased total dissolved solids. Also, not indicated in this illustration is
an increase that can occur in effluent COD values. The point to be made in this single and relatively
simple example is that one must attempt to cautiously consider all the factors in arriving at a de-
sired result. Having mentioned COD, which is now an established parameter, it should be said that
previously very little data had been collected on COD values, making the absence of such informa-
tion conspicuous.
How the individual chemicals in a vat dyeing of 100 percent cotton fabric contribute to the
pollution load is shown in table 11-11. Note that the dyestuff exerts no BOD5. Alternative oxidizing
methods demonstrate means of circumventing toxic chromate in the effluent.
The wasteload contribution from vat and disperse dyeing of 50/50 polyester/cotton is given in
table 11-12. The large contribution of BOD output from the carrier should be noted. The range of
wasteload contributions that can be obtained from scouring and piece dyeing polyester knits is
shown in table 11-13.
Carpet-manufacturing wastes will have characteristics similar to those from an integrated tex-
tile mill. (See appendix A, table A-13.) A plant providing backing will have a special problem with
latex wastes, which are usually best segregated and treated with chemicals before biological
treatment.
Table \\-5.-BOD loadings of polyester dye carriers
~1
Orthophenylphenol (most used)
Benzoic acid
Salicylic acid
Phenylmethyl carbinol
Monochlorobenzene (toxic)
BOD
ppm
6,000
27,000
24,000
19,000
480
lb/1, 000 Ib cloth
180
810
720
570
14
Source: John J. Porter et at., "State of the Art of Textile-Waste Treatment,'
EPA Pub. No. 12090 ECS, Clemson University, Clemson, S.C., 1971.
30
-------
Table \\-6.-Pollutional loads of wool wet processes
•
Process
•Scouring
Dyeing
Washing
Neutralization
Bleaching
pH
9.0-10.4
4.8-8.0
7.3-10.3
1.9-9.0
6.0
BOD
ppm
30,000-40,000
380-2,200
4,000-11,455
28
390
lb/1 ,000
Ib cloth
104.5-221.4
9.0-34.3
31-94
1 .7-2.1
1.4
Total solids,
ppm
1,129-64,448
3,855-8,315
4,830-19,267
1,241-4,830
908
Volume,
gallons
5,500-12,000
1,900-2,680
40,000-100,000
12,500-15,700
300-2,680
Table 11-7.—Pollution effect of cotton-processing waste
Process
Slashing, sizing yarn1 .
Desizing
Kiering
Scouring
Bleaching (range) . .
Mercerizing ....
Dyeing:
Aniline black ...
Basic
Developed colors .
Direct
Naphthol
Sulfur
Vats
pH
7.0-9.5
10-13
8.5-9.6
5.5-9.5
6.0-7.5
5-10
6.5-7.6
5-10
8-10
5-10
Wastes (ppm)
BOD
620-2,500
1,700-5,200
680-2,900
50-1 10
90-1,700
45-65
40-55
100-200
75-200
220-600
15-675
11-1,800
125-1,500
Total solids
8,500-22,600
16,000-32,000
7,600-17,400
2,300-14,400
600-1,900
600-1 ,200
500-800
2,900-8,200
2,200-14,000
4,500-10,700
4,200-14,100
1,700-7,400
Gallons waste
per 1 ,000
pounds goods
60-940
300-1,100
310-1,700
2,300-5,100
300-14,900
27,900-36,950
1 5,000-23,000
18,000-36,000
8,900-25,000
1,700-6,400
2,300-16,800
2,900-25,600
1 ,000-20,000
Pounds BOD
per 1 ,000
pounds goods
0.5-5.0
14.8-16.1
1.5-17.5
1.36-3.02
5.0-14.8
10.5-13.5
5-10
15-50
15-20
1 .3-1 1 .7
2-5
2-250
12-30
Pounds
total solids
per 1 ,000
pounds goods
47-67
66-70
19-47
38-290
185-450
100-200
150-250
325-650
25-250
200-650
300-1,200
150-250
1 Cloth-weaving-mill waste (composite of all waste connected with each process).
Some effluent-generating processes in the carpet industry follow:
Yarn Manufacturing
Wool scouring
Stock dyeing
Dkein dyeing
Yarn package dyeing
Space dyeing
Carpet and Rug Manufacturing
Beck piece dyeing
Continuous piece dyeing
Kuster system for carpet
Zimmer printing
Bradford printing
Stalwart printing
Deep dye printing
Latex application
Foam application
Vinyl application
Back, top, and warp
beam sizing for
woven carpet
Some Carpet Plant Products
Yarn
Tufted carpet or rugs
Woven carpet or rugs
Knitted carpet or rugs
Needlepunch carpet
31
-------
Table \\-B.-Pollutional load of manmade wet fiber processes
Process
Scour
Scour and dye
Dye
Salt bath
Final scour
Special finishing
Fiber
Nylon
Acrylic/modacrylic
Polyester
Rayon
Acetate
Nylon
Acrylic/modacrylic
Polyester
Rayon
Aery 1 ic/modacryl ic
Polyester
Rayon
Acetate
Nylon
Acrylic/modacrylic
Polyester
pH
10.4
9.7
— -
8.5
9.3
8.4
1 .5-3.7
—
6.8
7.1
—
_
—
—
—
—
BOD
ppm
1,360
2,190
500-800
2,832
2,000
368
175-2,000
480-27,000
58
668
650
_
—
—
—
—
lb/1 ,000
Ib cloth
30-40
45-90
15-25
50-70
40-60
5-20
2-40
15-800
0-3
10-25
15-25
20
40
10
60
2-80
Total solids
ppm
1,882
1 ,874
—
3,334
1,778
641
833-1 ,968
—
4,890
1,191
—
_
—
—
—
—
lb/1 ,000
Ib cloth
30-50
12-20
25-35
25-39
—
20-34
6-9
30-200
20-200
4-12
10-50
3-100
3-100
3-100
3-100
3-100
Suspended
solids,
lb/1,000
Ib cloth
20-40
25-50
5-15
0-3
1-20
242
5-20
—
2-6
3-7
3-50
3-50
3-50
3-50
3-50
3-50
Volume in
gal/1 ,000
Ib cloth
6,000-8,000
6,000-8,000
3,000-5,000
2,000^4,000
4,000-6,000
2,000^,000
2,000-4,000
2,000-4,000
500-1 ,500
8,000-10,000
2,000-4,000
500-1 ,500
3,000-5,000
4,000-6,000
5,000-7,000
1 ,000-3,000
Source: John J. Porter et al., "State of the Art of Textile-Waste Treatment." EPA Pub. No. 12090 ECS, Clemson University,
Clemson, S.C., 1971.
In the light of what has been said concerning the variability of textile wastes, it is doubtful
if a truly representative sample can be obtained to accurately show major sources of wastes in a
textile plant. A sample taken at one time can easily be different from that taken at the same time
the next day. Samples can show the range of composition that exists, but any results must be inter-
preted with a knowledge of the changing conditions at the specific plant. In reported cases, consult-
ant engineering firms have been misled because strong discharges were disposed of at night and
escaped sampling carried out during the day. Even automatic sampling is unreliable unless it is flow
related.
It appears that a truer picture of wasteload contributions can be made by obtaining usage
figures from inventory sheets over a period of time. This procedure requires that the BOD equiva-
lents of the chemical and the BOD levels to be expected from process liquors (flow rate) be known.
Knowing these equivalents and levels and knowing the weight of material and types of fibers treated
can give a measure of the material that will be removed in processing. Cross checks by occasional
sampling of processes, when appropriate, will give confidence in the use of such a method. This
method of estimating pollution loads is perhaps the easiest and most economical way to contribute
to an overall pollution abatement program.
REFERENCES
1 J. W. Masselli, 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 A. H. Little, "Treatment of Textile Waste Liquors," J. Soc. Dyers Colour., 33(7), 268-
273, July 1967.
32
-------
Table 11-9.—Enzyme starch desizing of 100-percent cotton-woven goods (60 percent warp)
[Production basis: 1000 pounds greige goods (containing 5 percent water), starch loading 14 percent
based on warp]
Chemical throughputs
Item:
Starch
Fats and wax
Oil
Enzyme
Salt
Wetting agent
Suspended solids
Water ,
Total
Input, pounds
84.0
4.4
0.4
1.6
2.5
1.0
Output, pounds
84.0 ,
4.4
0.4
1.6
2.5
1.0
5
12,500
'Unit
BOD, lb/100
Ib output
50
80
80
2
—
—
2
—
BOD output,
pounds
42.0
3.2
0.3
—
—
—
0.1
—
45.6
Effluent:
BOD '
Total suspended solids
Total dissolved solids
pH
Color
Oil and grease :
Toxic materials
Net effluent water
45.6 pounds
89.0 pounds
5.1 pounds
6-8
4.8 pounds
1.5 gal/lb goods
Source: Industrial Waste Studies Program, Textile Mill Products, May 1971, for EPA by A. D. Little, Inc., Cambridge, Mass.,
unpublished.
33
-------
Table 11-1 Q.—Polyvinyl alcohol desizing of 100-percent cotton-woven goods (60 percent warp)
[Production basis: 1,000 pounds greige goods]
Chemical throughputs
Item:
Polyvinyl alcohol
Wax
Oil
Suspended solids
Water
Total
Input, pounds
48.0
2.4
—
—
—
Output, pounds
48.0
2.4
—
5.0
12,500
Unit
BOD, lb/100
Ib output
1
80
—
2.0
—
BOD output,
pounds
0.48
1.92
—
0.10
—
2.50
Effluent:
BOD
Total suspended solids
Total dissolved solids
pH
Color
Oil and grease
Toxic materials
Net effluent water
2.50 pounds
5.0 pounds
48.0 pounds
6-8
2.4 pounds
1.5 ga I/I b goods
Source: Industrial Waste Studies Program, Textile Mill Products, May 1971, for EPA by A. D. Little, Inc., Cambridge, Mass.,
unpublished.
34
-------
Table 11-11 .—Vat dyeing of 100-percent cotton-woven fabric
[Production basis: 1,000 pounds greige goods]
Chemical throughputs
Item:
Dye
Sodium hydroxide
Sodium hydrosulfite
Dispersant '.
Hydrogen peroxide1
Acetic acid
Sodium perborate1
Sodium dichromate1
Acetic acid
Detergent
Sodium carbonate
Rework
Water
Total
Input, pounds
40.0
50.0
35.0
10.0
2.0
1.7
10.0
10.0
5.6
10.0
10.0
—
Output, pounds
1.6
50.0
35.0
10.0
0.1
1.7
10.0
10.0
5.6
10.0
10.0
42,000
Unit
BOD, lb/100
Ib output
-
—
22
50
-
35
—
—
35
50
„
—
BOD output,
pounds
—
—
7.7
5.0
-
0.6
-
—
2.0
5.0
—
0.4
—
19.1
Effluent:
BOD
Total suspended solids
Total dissolved solids
pH
Color
Oil and grease
Toxic materials
Net effluent water:
19.1 pounds/1,000 pounds greige goods, Nat. avg.
117-127 pounds
12.5 (0.15 percent sodium hydroxide)
1.6 pounds
Chromium = 3.5 pounds
5 gal/lb goods
'Alternatives. ,
Source: Industrial Waste Studies Program, Textile Mill Products, May 1971, for EPA by A. D. Little, Inc., Cambridge, Mass.,
unpublished.
35
-------
Table 11-12.—Vat and disperse dyeing of 50/50 cotton/polyester knit fabrics
Including scouring or partial bleaching
[Production basis: 1,000 pounds goods]
Chemical throughputs
Item:
Vat dye
Disperse dye
Carrier
Monosodium phosphate
Dispersing agent
Sequestrant
Sodium hydrosulfite
Sodium perborate
Detergent
Natural impurities
Rework
Total
Input, pounds
20.0
7.5
40.0
25.0
10.0
5.0
25.0
5.0
12.5
25.0
Output, pounds
1.0
0.375
40.0
25.0
10.0
5.0
25.0
5.0
12.5
25.0
Unit
BOD, lb/100
Ib output
—
5
85
-
50
50
22
-
50
50
BOD output,
pounds
—
0.02
34.00
; —
5.00
2.50
5.50
-
6.25
12.50
2.6
68.4
Effluent:
BOD
Total suspended solids
Total dissolved solids
pH
Color
Oil and grease
Net effluent water
68.4 pounds
189
12
1.4 pounds
30 gal/lb goods
Source: Industrial Waste Studies Program, Textile Mill Products, May 1971, for EPA by A. D. Little, Inc., Cambridge, Mass.,
unpublished.
36
-------
Table I \-~\3.-Scouredand dyed polyester
[Production basis: 1,000 pounds fabric]
Chemical throughputs
Item:
Nonionic surfactant
Anionic surfactant
Carrier— o-phenyl phenol
or trichlorobenzene
or biphenyl (atmospheric beck)
or butyl benzoate (pressure beck)
Disperse dye
Sequestrant (EDTA) '
Acetic acid, 56 percent
or monosodium phosphate
or monosodium phosphate acetic acid.
56 percent (preferred)
Soda ash
Sodium hydrosulfite
Water
Input, pounds
30-35
10
60-150
60-150
60-150
15-40
5-40
2!5-5
20
20-30
5
50
10
Output^ pounds
30-35
10
60-150
60-150
60-150
15-40
.2-1.5
2.5-5
11
20-30
3
50
10
290,000
Unit
BOD, lb/100
Ib output
3
80
140
3
140
140
5
2
35
0
35
0
22
BOD output,
pounds
.1
8
84-210
2-5
84-210
21-56
.05
.1-.2
4
0
1.5
0
2.2
Effluent—calculated: ;
BOD
Total suspended solids
Total dissolved solids
pH
Color
Toxic materials
Net effluent water
100-225 pounds (atmospheric beck); 33-70 (pressure beck)
Indeterminate
80-90 pounds
6-8
Indeterminate
Orthophenyl phenol, trichlorobenzene
35 gal/lb goods (average)
NOTES: Data given above refer to disperse dyeable fiber, but are essentially the same for cationic-dyed fiber.
Data refer to polyester knits, piece dyed, using regular or textured yarn. Package dyeing will use the same chemicals, but less
water. For woven goods, size must be added—30 Ibs sodium polyacrylate; output, 30 Ibs; BOD, 0.3 Ib.
Allow additional chemical and BOD output for goods to be reworked; assume 3-5 percent of fabric is reprocessed.
BOD outputs calculated from data given in American Dyestuff Reporter, pp. 39-42, August 29,1966. A biodegradable
anionic surfactant was assumed.
Source: Industrial Waste Studies Program, Textile Mill Products, May 1971, for EPA by A. D. Little, Inc., Cambridge, Mass.,
unpublished.
37
-------
-------
Chapter III
FLOW REDUCTION*
The less water used in the production facilities, the less water that will have to be treated at the
waste-treatment plant prior to discharge. In this chapter, some of the areas in which water savings
can be obtained will be reviewed and a few examples where J. P. Stevens and Company has made
significant water-flow reductions will be given.
Water has been cheap too long and has not been rationed or figured into the cost of the prod-
ucts. We have not had time, with all the other more pressing production-cost savings, to look at the
advantages of saving and reusing water. However, as the price of treated water goes up and the price
of waste treatment increases much more to meet the current governmental demands, we now have
the conditions to encourage water conservation.
Some general areas to consider in water conservation are the following:
• Turn off water to equipment that is not being used. Use automatic shutoffs on hoses, etc.
• Supply only the needed amount of water to a machine. (Don't use 30 or 40 gallons when
20 gallons will accomplish the same job.)
• Modulate water use depending on throughput of material. Use less water for narrower width
fabric than for wider fabric.
• Reuse nonchemical treated cooling water.; Reclaim by running through a cooling tower or
reuse in processes not requiring tap-water quality.
• Chemically treat waters for reuse. Print wastewater can be clarified and returned to wash the
blankets and screens of the print machine.
• Steam condensate return.
CASE HISTORIES
Four case histories in which some of the above methods were utilized are described briefly.
Plant 1
A plant with 13-300-pound kiers on stream with no water recovery was using approximately
700,000 gpd. Water supply was limited, pressure dropped, etc.
Five 1,000-pound kiers were added, and a recovery system was activated into a new hot water
system under pressure. In addition, the plant restricted water use by placing flow reducers into
large lines. Current wastewater is approximately 400,000 gpd.
*Prepared by Samuel H. Griggs of J. P. Stevens and Co., Inc., Piedmont, S.C.
39
-------
Plant 2
Where 30-35 gallons of water were being used per pound of fabric dyed, conservation reduced
the use to 18 gallons per pound of fabric dyed. This was accomplished by examining the process
and restricting the water use.
Plant 3
In plant 3, there was a reduction of approximately 800,000 gpd going to waste treatment
effected by the addition of a cooling tower on nonchemical, treated cooling waters.
Plant 4
In plant 4, there was a savings of 288,000 gpd effected by adding a cooling tower to reclaim air
compressor cooling water. As a result, approximately $18,000 per year was saved.
40
-------
Chapter IV
WATER REUSE*
In the textile industry, there is a fertile area for research in the field of water management and
water reuse. The problem in the past has been that too few systematic approaches have been
attempted. Almost all industrial water-using operations can reduce their total consumption; textiles -
are not the exception. Most textile plants use more water than is absolutely necessary, and the use
is constantly increasing. With top management backing, large reductions in water consumption can
be made. Without this backing, the operating personnel regard suggestions as outside interference
and nothing constructive is accomplished. Even with top management backing, it is a slow process.
Water reduction and water reuse, however, are not necessarily synonymous. Water reduction is
the use of less water in production, that is, gallons per pound of product. Water reuse, however, is
something else; it is the use of the same water more than. once. An example would be to use rinse
water from one operation for makeup water in a second operation. This results in a reduction in
total production water use but does not necessarily reduce the gallons used per pound of product.
There are many questions that require answers before effective water reuse can be accomplished.
Some of these are as follows:
1. What level or levels of water quality is available within the plant?
a. What is the minimum level or levels of water quality actually required for the various
dyeing and finishing operations used? Unless the minimum level of water quality
necessary for processing is known, no effective program of reuse is practical.
b. If more than one quality is acceptable or if the minimum acceptable level is lower
than the level in general use, what are the economics for using these various levels,
including piping changes, storage cost, pumping cost, water-treatment cost, and
miscellaneous?
c. If the water used is purchased water (municipal supplier), then what effect will a
large reduction in water use have on your supplier's cost? A reduction in water
production usually increases the cost per gallon. What are the economical benefits
to you, if any? Do you have a contract Math a minimum use required, that is,
minimum monthly charge?
d. Are there processes in which relatively clean washing or rinsing waters could be avail-
able for collection and minimum retreatment for reuse at a slightly lower quality
level, if a use is found?
e. What would be the cost for treatment to restore this reusable water in (c) to a level
consistent with the minimum acceptable level? Can these costs be related to (b)?
2. What reductions in flows to the waste-treatment plant can be realized if clean rinse water is
reused? What increase in load will accompany a reduction in flows?
*Prepared by Thomas A. Alspaugh of Cone Mills Corporation, Greensboro, N.C.
41
-------
3. Can the waste-treatment plant handle this increased organic strength caused by a reduced
volume loading?
a. Are there constituents in this wastewater that can be handled in a dilute solution but
when concentrated by water reuse will be harmful in the waste disposal plant?
b. Can they be replaced in processing without materially affecting quality or produc-
tion? At what cost? How is this related to cost of treatment to remove them?
4. Are there materials in the waste that can be handled but cause treatment difficulties? Can
they be replaced?
5. Are there materials in this waste that leave residues after treatment that may be unaccept-
able in the receiving stream?
6. Are there processes in which water can be recycled in a closed loop and no discharge made
to the sewers? If so, what are the economics, taking into account water treatment and
disposal cost?
As a result of these general questions, it can be seen that there are many unknowns and there
are several ways to start, depending on how complete an answer is needed. One is to review the
processes and water-quality requirements needed and then tailor the uses to the minimum quality
requirements for each process. This can involve collecting all clean water for reuse without treatment
or with only minimum treatment and operating two water systems.
A less-involved way would be to survey effluents and determine where the clean water located
can be reused. This usually means reusing only clean cooling water for rinses. In any event, the
minimum water quality for processing needs to be determined by testing before reuse of clean water
is attempted.
The problem, then, comes down to two schemes:
1. Reuse of cleaner water without retreatment
a. Volumes found? :
b. Volumes needed for a particular process where reuse indicates some success?
c. Is this cleaner water always available? This means both processes—one producing
clean water for reuse and one using it—must operate on the same schedule. (This is
a most important consideration.) Where do you get water if reuse water is not avail-
able? Will this be a manual or automatic operation? Where will cleaner reuse water
go if, after piping changes are made, some days it is not needed? The ideal situation
is to have more reusable water than needed and waste the excess back to the drain.
2. Reuse of clean water with treatment
a. Treatment required?
b. Treated water quality needed and produced?
c. Storage and handling systems?
42
-------
In general, if reuse does require treatment, a separate water system will be necessary in
most cases. The separate systems would be a drinking and high-quality-use system plus a
lower quality service-water system. In some plants that already have a separate drinking-
water and service-water system, a third water system may be necessary. It can be noted
that this will increase the total water cost as the raw water use is reduced.
CASE HISTORIES
Cooling Water Reuse Without Treatment
Cooling water that does not come in contact, with the cloth or have excess added chemicals can
be reused directly.
• Cooling water in hydrosulfite operation reuse as indigo wash water
• In printing, cooling water reused to wash blankets or back greiges
• Cooling water as final rinse in dyeing
Treatment for Reuse
Ultrafiltration. There are several Federal grant projects under way concerning reuse of water
after Ultrafiltration. The reports to date indicate that this can be a practical approach in certain
situations. Operation of this type of equipment produces a water in quality only a little below
reverse osmosis. This water can be reused anywhere drinking-quality water is used in processing,
but the cost can be high. This could be especially appealing, however, in a single dye-shade dye-
house, then dyes and heat, as well as water, could be reused.
Chemical-Biological Treatment. Chemical treatment following biological treatment has been
the subject of several: research projects also.
• The effluent from a fiber-manufacturing biological-treatment plant was treated chemically,
then filtered for reuse in air conditioning and other cooling operations for use in fiber
manufacturing.
• The effluent from an integrated textile waste-treatment plant was treated chemically after
granular carbon was added into the biological system. This produced water that could be
reused in processing.
One of the things that will be noted in the use of chemical coagulants with textile waste is the
high consumption required. In general, only certain chemicals seem to work, usually alum and the
iron salts alone, or in combination with a high-molecular-weight polymer, alum in the range of 300-
700 mg/1 and FeCl3 from 500-800 mg/1 without a polymer. The use of a polymer will reduce
chemical consumption approximately one-third, but requirements will be high in the 3-10-mg/l
range. The cost of chemical treatment could be in the range of $80-$150 per million gallons in addi-
tion to the cost for biological treatment. In general, this means the cost will be $100-$150 per
million gallons for high-grade biological treatment, plus $80-$150 per million gallons for chemical
treatment.
The cost of storage and pumping facilities will be in addition to these costs. This reused water
would then be blended into and would replace a portion of raw water for processing, keeping in
mind that there will be an upper limit on dissolved solids that can be tolerated.
43
-------
This could be especially appealing, however, in a single dye-shade dyehouse; then dyes and
heat, as well as water, could be reused.
Reuse of water in processing can be carried out successfully from an engineering and production
standpoint; however, the main objection to date is cost, which will be two to three times the present
one. There does not seem to be any means of reducing this figure to what is considered a more
reasonable level. The approach has been to try and also to recover heat or production chemicals to
offset the higher figure.
44
-------
Chapter V
WASTE SEGREGATION*
Waste segregation has been; practiced in the textile industry for many years. The segregations
that have been generally used were those that enabled the industry to recover something of value
that was being discharged in the waste. This chapter discusses the segregation and recovery practices
that have been used at Cannon Mills Company.
Heat recovery, is an item that has been in use at Cannon Mills for over 40 years. A dual water
system was developed for the bleachery and provided a means of reuse of hot water that was dis-
charged from the steam plant.
Cannon Mills Company began its waste-treatment program in 1953. After the waste survey was
completed and evaluated, it was evident that segregation of the wastes at the bleachery would pro-
vide the most economical treatment for the waste.
The first step in this program was the .construction of three pipelines to the waste-treatment-
plant area. One pipeline collected the desizing wastes and transported them to the plant for im-
mediate treatment. The second pipeline collected the highly alkaline wastes and transported them
to a storage lagoon at the treatment plant. The third pipeline collected all of the remaining wastes
from the bleachery. These additions were completed in 1955. Operating efficiencies at the waste-
treatment plant were greatly improved, since it was possible to control the pH continuously.
A dye plant was; constructed for continuous dyeing of towels and sheets, and a system to
segregate the dye wastes was provided at that time. All of the hot waste waters were collected and
screened prior to heat recovery units. The heat recovered by these units saved the company approx-
imately $600 per day. They also delayed construction of ah additional steam plant for 5 years.
Three additional raw-water pipelines were made available to the waste program in 1965. These
pipelines provided a means for planning further segregation at the two dye plants.
\ '
Stream standards had been changed and now required a much higher degree of treatment.
Additional facilities that were designed to provide 95 percent treatment efficiencies were con-
structed from 1967 to 1972. Included in this construction were four concrete holding tanks used
for storage of wastes to improve weekend operation. *
Two tanks are used for dye-waste storage and are equipped with floating aerators to mix the
waste and also to provide oxygen to the waste. This arrangement provides 3 million gallons of
dye waste for the treatment plant when the mill is not in operation. Another tank with 2.6 million
gallons capacity is used for caustic-waste storage. This provides continuous pH control that is re-
quired for high-efficiency operation. The final tank of 2.6 million gallons capacity will be used for
the storage of spills arid overflows thai; occur in the bleachery and dye houses.
There are now seven pipelines that are available to the waste-treatment system. These pipelines
provide a means for seven different types of wastes to be blended at the waste-treatment plant. The
blender is capable of supplying five biological treatment units with any combination of wastes that
is desired.
*Prepared by John L. Brown, Jr., of Cannon Mills Company, Kannapolis, N.C.
45
-------
-------
Chapter VI
PANEL DISCUSSION ON
SUBSTITUTION OF PROCESSES AND MATERIALS
GENERAL CONSIDERATIONS*
Introduction '
This panel discussion on the in-plant control of pollution involves the substitution of processes
and materials, the results of which will reduce or prevent waste, both in quantity and quality. The
resultant overall organic load to the receiving stream will be reduced in poundage, and the hydraulic
flow will be reduced in quantity. In order to accomplish, this, there are many long-range aspects of
the problem and very few short-range quick solutions.
As has been seen earlier, there are certain prescribed steps that must be taken in a plant in order
to define the problem. These steps are:
• The waste survey
• Major sources of waste
• Flow reduction
• Reuse of water
• Waste segregation
• Substitution of processes and materials
All of these items are interrelated, but after the first five have been instituted, the last item will
continue on ad infinitum. In reference to this last item and before the textile industry is discussed,
there are examples in other industries that should be examined.
Metal-Working Industry
In the metal-working industry, certain parts have, until recently, been made into very intricate
forms and shapes by machining and/or hand shaping. This produced a part with a high metal-waste
factor accompanied by waste machine oils, coolants, and lubricants. Due primarily to the inherent
high cost of such an operation and a demand for a higher volume of such parts, metallurgists have
developed the powder metallurgy technology. The vast quantities of waste shavings of expensive
alloys have been eliminated, and the machining phase is drastically reduced or eliminated by the use
of powder metallurgy. The net result is a better product at a cheaper price, with an accompanying
high reduction of waste load.
*Prepared by William J. Day of Davis and Floyd Engineers, Inc., Greenwood, S.C.
47'
-------
Paper Mills
The manufacture of paper as we have known it over the past few decades has been accomplished
by a combination of chemical and mechanical means. For the southern pine tree, the sulfite pulping
method gave way generally to the sulfate pulping method. In both of these processes, a high degree
of chemical separation or release of the fiber has been employed. This has been accompanied with a
very high use rate for water and a high organic-waste production, principally in the form of ligriin,
terpenes, resin, and fatty acids. The paper industry is presently taking a very hard look at shifting
toward more mechanical and less chemical pulping. In addition, different means of chemical pulping
are being investigated. These methods show promise in cutting down on the amount of water re-
quired and reducing to a great degree the organic waste portion.
The two examples presented previously are broad generalizations of what can be done in other
industries to reduce waste. There are some areas where similar approaches possibly could be taken
in the textile industry.
Nonaqueous Textile Processing
A great deal has been said in recent months concerning nonaqueous textile processes. What has
been said has created a great deal of controversy. The American Association of Textile Chemists and
Colorists held a seminar in Atlanta in 1972 to review the technology currently in use in non-
aqueous textile processing. The general consensus of that seminar was that success has been
generally limited to small batch operations concentrating on specialty items. Personnel from within
the textile-manufacturing industry have seen very little promise for success in this area in which
large, continuous processes are involved. On the other hand, textile-equipment manufacturers are
somewhat more optimistic. They feel that research and development will yield processes and equip-
ment for large, continuous, nonaqueous systems that can be substituted for the various unit proc-
esses presently being used in the processing of textiles. Therefore, in the nonaqueous-textile-
processing field, it is generally conceded that we should proceed with guarded optimism. The pres-
ent situation in this field compares very closely to the situation in powder metallurgy in the late
1940's. We can see that the powdered metallurgy industry was successful in applying new technology.
There is hope here, but our optimism, as mentioned previously, must be guarded in light of reality.
Changes in the Basic Process of Handling the Fiber
Most attendees at this conference are here to learn specifically what basic process can be
changed in the many textile-unit processes that will result in savings (capital, time, waste, etc.). I do
not believe that many earth-shaking, quick answers are available. It is hoped that during the dis-
cussion period, an exchange of ideas may result in someone coming up with a new idea that may
change the basic process of handling the fiber. A whole new technology, such as the use of non-
aqueous solvents, would be required. Another area that needs some discussion is the elimination of
the mercerizing process. Can it be eliminated? This process is the source of high alkalinity in the
waste and it needs some radical thinking. Some thought should be given to a radical departure in
the types of dye being used. Some progress has been made in this area with high-temperature dye
machines, but more thought and time should be spent on this matter. Other chemical substitutions
should be looked into. For instance, there has been a gradual shift from starch sizes to the poly-
vinyl. Starch is treatable in a biological waste-treatment plant. The polyvinyl sizes are difficult to
treat. Some attention has been given to their recovery and reuse. There may be some merit in this
procedure in technology in order to get the best characteristics of starch and the polyvinyl and still
have a biodegradable or recoverable size.
48
-------
In-Plant Equipment and Flow Changes
In the dyeing and finishing processes, the amount of water used and the scheme of flow within
any one process varies widely from plant to plant and.is due primarily to the artist who is operating
the specific process in question. It is extremely difficult to change these work practices because
some of the artists insist that the old method is the only one that will work. This entire line of
thinking must be changed. For instance, if it is assumed that a textile dyeing and finishing operation
uses 5 million gallons of water per day, then it can be found that an excess of l*/2 million gallons per
day of water can be readily recycled, reused, or conserved in some manner. The savings of water is
about equally distributed between the boil out, mercerizing, bleaching, and dyeing operations. In
each instance, water recycle in selected areas accounts for the water savings. This approach has not
found favor with plant operating personnel because of apparent quality degradation in the product.
The best way to prove that quality will not be affected adversely is to isolate one complete line,
modify it, and challenge them to solve the water-conservation problem. They generally find that
they can make it work and in so doing, become the authors of changes on the remaining lines.
The new high-temperature dyeing machines offer some areas for water conservation, providing
the cycles of operation are controlled very precisely and the excesses of water are cut back. It can
generally be found that the recommended wash cycle can be cut back appreciably, and about a 25-
percent overall water savings can be realized.
Once the water use has been reduced to the minimum, then other problems can be attacked.
In many dyes and dyeing operations, heavy metals, such as chromium, zinc, and copper, are en-
countered. These metals end up ultimately in the effluent stream. In order to remove them, the
streams containing them should be isolated and chemically treated. This treatment is the old stand-
ard "redox" reaction between hexavalent chromium and sulfur dioxide, followed by a metal
participation at pH 8.5.
Chemical Substitution •
Of particular interest today is the removal of heavy metals from the effluent stream. One major
source of heavy metals may be from the' chromate oxidizer used in certain dyeing processes and
operations. The elimination of the chromium problem has been addressed in many ways. Some
manufacturers have switched to hydrogen peroxide or the iodates. Both of these process modifica-
tions eliminate the chromium, but they may result in product degradation.
WHAT CAN CHEMICAL SUBSTITUTION PRODUCE IN POLLUTION REDUCTION?*
Substitution of Materials
Masselli1 stated that his data demonstrated the possibilities of substantial pollution reduction
through the substitution method were very bright indeed. He expected that the textile industry, as
a whole, could quickly reduce its pollution load by 40-70 percent through methods suggested by
him in 1956. He felt that with additional research and experience, reductions of 70-90 percent
could be obtained. Since 1956, however, additional pollution parameters, such as COD, ultimate
BOD, color, and stubborn or refractory chemicals (produced as a result of consumer demands), have
probably modified considerably the direction of potential gains achievable from substitution.
*Prepared by Michael S. Bahorsky of the Institute of Textile Technology, Charlottesville, Va.
49
-------
Substitution should ideally assume the direction of easily treatable or reusable materials in
terms of waste-treatment technology, recoverability, or reuse. Conventional biological systems may
at times require low-BOD chemicals to be substituted. Physical-chemical methods will also work
more efficiently on certain materials than others. Recovery of carboxymethyl chloride (CMC) size
material has been demonstrated over starch and polyvinyl alcohol. Reuse of waters high in certain
salts may be tolerated in certain processes at relatively high concentrations before quality is affected.
Masselli2 pointed out in 1959 that in certain mills, it was the practice to establish scouring and
finishing formulations to take care of extreme conditions that may actually occur only 5 percent of
the time. Some of these formulations could exceed the required concentrations by safety factors
up to 60 percent. Other mills might practice switching similar chemicals based on current price
trends. Since it is indicated that process chemicals contribute to the bulk of the textile industries'
total waste load, it is suggested that a stable inventory base would be an integral first step as part of
an approach to a successful waste control program. Obviously, cutting down excessive use of chem-
icals will help the pollution problem and costs without affecting the final product in most cases
(supervised study is recommended with suitable record keeping).
A useful listing of the BOD characteristics of textile chemicals is published in the August 29,
1966, issue of the American Dyestuff Reporter. Examples of chemical consumption and BOD load-
ings in cotton finishing are given in table B-I of appendix B.
Recovery of CMC Warp Size. Dr. Carl E. Bryan (North Carolina State University) has found
that recovering CMC by precipitation with aluminum sulfate (alum) allows reuse of the CMC for
four cycles of sizing, desizing, and recovery. Bryan's work shows that it takes about 1 pound of
alum ($0.03/lb) to recover 1 pound of CMC. Work on recovery of starch and polyvinyl alcohol has
not demonstrated an attractive procedure.
Low-BOD Polyester Dye Carrier. Masselli1 suggests the use of monochlorobenzene in place of
other carriers for dyeing Dacron.
Dye Carrier Reuse or Recovery. Masselli1 suggests that reuse or solvent recovery of dye carriers
should be investigated.
Substitute for Acetic Acid in Dye Bath. Substitution of formic acid for acetic acid in dyeing
gives a substantial reduction in BOD and, because of its lower equivalent weight, can give a cut in
costs.3
Chemical
Acetic acid
Formic acid
BOD equivalent (Ib/lb)
0.64
0.12
Oil and Lubricant Substitute. Carding oils and antistat lubricants should be replaced by mineral
oils with nonionic emulsifiers and other low-BOD substitutes according to Masselli.1
Dyeing Wool—Replace Acetic Acid. Masselli4 demonstrated that dyeing procedures using acetic
acid can have 85 percent of the BODS contributed by the acid. If ammonium sulfate is used in
place of acetic acid, the BOD can be reduced the full 85 percent. Furthermore, the ammonium con-
tent will serve as a nutrient in the activated-sludge process. Of course, the salt content of the waste
will be increased.
50
-------
Wool Fulling. Soap used in fulling can contribute high-BOD levels.1'3 If detergents or sul-
furic acid are used, the table below shows the BOD equivalent of a "hard" detergent (Lissapol N)
and that of a "soft" detergent (Empilan KL10).
Chemical
Soap (textile flakes)
Lissapol N
Empilan KL10
Sulfuric acid
BOD equivalent (Ib/lb)
1.06
0.06
0.72
0
The Surfactant and Foam Problem. Many surfactants, such as the alkylphenol ethoxylate and
ethoxysulfate types; are resistant to attack by bacteria found in treatment systems and streams.
Consequently, such surfactants continue to foam and pollute natural waters and retard the efficiency
of treatment systems. The River Die-Away Test, shown in figure VI-1, indicates what happens using
low-bacterial populations as found in natural rivers under laboratory conditions. The Tergitol S
series (linear alcohol ethoxylates and derivatives) of nonionics degrade more rapidly than the other
surfactants compared. Such a test, coupled with foaming tests and performance application tests
(wetting ability, leveling, scouring assistance, bleaching assistance, etc.), will indicate the optimal
product for a specific application.
An interesting finding appeared in the February 1972 American Dyestuff Reporter. EPA in-
vestigators from Athens, Ga., found an eightyfold increase in p-nonylphenol between a carpet yarn
mill's treatment influent and effluent. Their explanation was that the phenol increase was likely due
to biological degradation of the surfactant.
In-Plant Textile Changes at Burlington. In-plant studies to reduce volume and pollution load
of wastes within Burlington are summarized below.5
Water use was reduced by returning pump cooling water to a reservoir and by better control of
the pressure water filter backwash. A program was put in effect to reduce the volume of water used
in the various processes. This program evolved slowly because of the reluctance to change or to
reduce any component of the operation, such as the elimination or reduction of various washing
operations or the reuse of these wash waters in other processes. Reuse of certain wash waters in
dyeing has shown promise, but these methods of reuse were not studied further.
The pH of the waste was reduced by the installation of a caustic recovery unit. This unit has
resulted in a significant reduction in the pH and hydroxyl alkalinity, making the waste more sus-
ceptible to biological action. The caustic recovery not only reduced the pollutants discharged to the
stream, but also was expected to be a good investment by returning reusable caustic soda to the
process.
One of the major sources of BOD load was starch used in the warp sizing operation. Because of
this, CMC was evaluated as a replacement for the starch, and after nearly 15 months of studies and
trials, methods were developed that permitted the substitution in the mill operation. While substitu-
tion of CMC for starch sizes resulted in an overall BOD reduction of about 50 percent for the entire
mill operation, it was found to be somewhat more expensive than starch, and additional studies were
made with combinations of CMC and low-BOD starches in order to achieve the same BOD reduction
at a lesser cost of sizing materials. This was successful.
Further studies of chemicals in the plant brought about the substitution of detergents for soaps,
reducing the BOD of many individual samples by 70-80 percent. Some finishes were found to have
less BOD than others, and although the overall waste volume of finishes was relatively low, substitu-
tions of finishes were made whenever practicable. Certain dyestuffs were given consideration because
51
-------
ioo
DAYS
(a) Such as, "Igepal" CA-63O (General Aniline & Film);
"Polytergent"G-300(Olin); "Triton" X-100 (Rohm and Haas):
(b) Such as, "Igepal" LO-630 (General Aniline & Film); "Sterox"
MJB (Monsanto) ^
(c) Such as, "Alipal" LO-436 (General Aniline & Film)
NOTE: Nonylphenol derivatives; such as, "Polytergent" B-300
, (Olin); "Igepal" CO-630 (General Aniline & Film); "Triton"
N-100 (Rohm and Haas); and TERGITOL Nonionic NPX,
are similar to the octylphenols in biodegradability.
Figure VI-1. Measurement of biodegradation by the River Die-Away Test. (Anionics by
methylene blue; nonionics by cobalt thiocyanate; 20 mg/l initial concentration.)
Table VI-1. Data reflecting in-plant chemical effects of substitutions
Item
5-day BOD, ppm
pH
Total alkalinity, ppm
Hydroxyl alkalinity, ppm
Carbonate alkalinity, ppm
Before
changes
410
11.5-12.0
1,600
-
-
After
changes
210
10.0-10.5
560
180
380
Reduction
190
2.0
1,040
-
-
of low pollutional load, but studies were not carried to completion. Table VI-1 shows some effects
after chemical substitutions.
52
-------
Process Changes
Washing Focus for Water Economy. The greatest potential for improved water economy in the
textile industry stems from the use of better washing methods. It is suggested that washing machines
have not been conventionally designed with water economy as a high priority. In this' event, it is
likely that more efficient washers can be developed.4 Rodney-Hunt, manufacturers of the Tensitrol
washer, compared their washer with two tight strand washers and suggested'that up to 85 percent
less water use may be achievable.
Why Use Large Quantities of Water? A British survey6 asked Me question ot Why l'ar^e"aQiiStmts
of water were used in certain mills. Two major reasons were identified. First, it was considered
necessary to some for technical reasons. Others felt quality suffered if copious amounts of water
were not used. Natural reluctance to change might also be added. Perhaps the best way to overcome
such opposition is to run carefully supervised trials.
Yarn-Dyeing Plant Cuts Water Use. A yarn-dyeing plant was reported7 to cut water require-
ments from 75 to 35 gal/lb by discovering and eliminating waste areas.
Use More Lots of Less Water. A British survey6 of the processes involved in scouring wool re-
vealed that considerable savings could be made—in one case a reduction from 24 gal/lb wool to
3.3 gal/lb was made by using four or five lots of water at a short liquor/cloth ratio.
Water-Consumption Rule. As a rule of thumb, the shorter the wet-processing sequence, the
lower will be the water consumption; the longer the sequence, the greater the consumption.8 Valid
parameters in optimizing a wet process for minimal water consumption include temperature, flow
rates, fabric speed, water level, and tank size.
i
Counterf low Wash Boxes Save Water. Dixit8 stated that the countercurrent system of washing
is readily adaptable in J-box bleaching, since it is possible to do away with storage tanks. A system
of pumps with filters and suitable pumps are required.
Bleach-Range Considerations. It has been suggested that if a cotton mill with continuous
bleaching, using a caustic saturator-J-box-washer-peroxide saturator-J-box-washer sequence, reused
water from the peroxide washer in the caustic washer, up to 33 percent savings in water might be
accomplished. Systems using two washers after the caustic and peroxide steps might save up to
60 percent.9
Reuse Scour Rinse to Desize. Masselli4 suggested reusing caustic scouring rinses in cotton mills
for desizing. Storing these wastes in tanks can equalize them and allow the high-BOD load to be
released evenly to treatment. Such a combined waste could contain 60-90 percent of the BOD in
3 percent of the water volume.
Heat Reclamation Recommended. Masselli4 suggested that heat exchangers should be used,
particularly since reduction in water use usually means an increase in effluent temperature. It has
53
-------
been observed by the EPA that the textile industry widely practices heat reclamation, so the waste-
waters sent to treatment plants usually do not present any significant thermal-shock problems.1 °
By simply installing copper piping in the waste lines, some mills have preheated water used in
the dyehouse. Meyer1 x suggested that a finishing plant with a wastewater flow of 1,000 gpm and a
temperature of 140° F may expect savings in recovered heat from this water that would be equal to
30,000 pounds of steam an hour. He envisioned a plant saving $90,000 a year in 1963. Brown12
cautioned that screens should be used in cotton-processing plants before heat exchangers.
Reuse Cooling Water. Cooling waters may represent a large volume of relatively pure water that
might be collected and reused. Williams5 reported a plant that returned pump cooling water to a
reservoir. Better control of pressure-filter backwashes was established and water use was reduced
significantly.
Mercerizing Caustic Recovery. It has been suggested13 that if there is as much as 400 tons of
sodium hydroxide available annually, at a minimum strength of 2 percent, its recovery by evapora-
tion for reuse may be economically feasible. Dialysis, another way to recover caustic, provides a
purer solution for reuse but requires more sophisticated control and attention. Souther14 reported
that caustic recovery from a plant reduced the pollution load significantly, increased treatment
efficiency, and resulted in treatment facility construction cost savings.
Scouring of Raw Wool and Cloth. The treatment of textile effluents, containing large quantities
of grease, presents special problems because wool grease and many of the traditional processing
lubricants are not readily biodegraded. Even when recovery of wool grease is practiced, by centri-
fuging or acid cracking, residual grease present in treated liquor may be as high as 10,000 mg/1 and
is unlikely to be less than 1,000 mg/1. Additional treatment is still required, therefore, before the
effluent can be discharged to a river.
Methods examined in detail at the Wool Industry Research Association for the treatment of
effluents such as these have included electrophoresis, dialysis, reverse osmosis, and distillation.
These studies have resulted in the development of the Traflo-W process (figure VI-2). The process
Holding tank
Filter cloth
\
Ferrous
sulphate
Cake
Rotary vacuum
filter
Filtrate
Figure VI-2. Outline of mill-based pilot-scale plant for treatment
of piece-scouring effluent.
54
-------
essentially entails chemical coagulation of impurities, followed by vacuum filtration. At its opti-
mum, it is capable of removing 100 percent of the suspended solids and grease and of reducing the
BOD by at least 80 percent. Manufacture of this treatment plant is covered by a license agreement
between Wira and Petrie and McNaught Ltd.6
Wool-Solvent Extraction. Masselli1 stated that "if grease and suint are removed by solvent
extraction, this load [as shown below] may be reduced by approximately 200 Ibs." The use of
methylisopropyl alcohol was suggested. It should also be pointed out here that suint is not readily
soluble in most common nonaqueous solvents, that is, it is primarily water soluble. Furthermore,
wool industry sources15 indicate that only one known company has survived with a solvent-
scouring system, apparently because of high economic factors. Since water systems follow solvent
systems, actual pollution savings must be evaluated.
Fiber
Greasy wool
Total pounds BOD/100 Ib cloth
219-720
Riggs-Lombard Solvent System. John Stewart (Northern Textile Association) described the
potential application of a new Riggs-Lombard solvent system for reducing pollution load (in terms
of lb/1,000 Ib goods), total water consumption, chemicals used (detergents, etc.), labor costs (people
required), and time spent (faster than aqueous methods). The 1,1,1-trichloroethane solvent is said
to have less than 10 gallons per day loss from a 1,200-gallon-capacity unit. Lost material is not dis-
charged to the atmosphere in this completely sealed system. Used on a wool-nylon-cotton blend
fabric, this solvent process of finishing has cut water consumption from 150,000 to 10,000 gpd. A
92-percent BOD reduction in terms of lb/1,000 Ib of goods has resulted, although in concentration
terms (mg/1), higher values occur. :
Solvent Processing. The "State of the Art in Solvent Processing" is documented in the pro-
ceedings from the January 1973 AATCC Symposium held in Atlanta, Ga. Perchlorethylene emerges
as the solvent of choice. Only solvent scouring and finishing of synthetic knit fabrics is widely
practiced and growing. Solvent scouring is practiced in wool finishing to remove spinning, oils, sizes,
and tints.4 Solvent dyeing awaits suitable dyestuffs and equipment. General application of solvent
sizing, desizing, scouring, bleaching, and finish chemicals and equipment offer little advantages over
aqueous methods. However, developmental work is progressing rapidly enough to clearly envision
use of solvent processing in the future.
Automation. Well-designed and properly applied controls, especially in dyeing operations, can
bring about reductions in water use, chemicals, and dye use. Gelders16 reported water use reduced
by one-third using punchcard, programed-type, dye-cycle controllers. Instruments that measure
percent pickup indicate when cloth is clean, assist with uniform application of chemicals, and pro-
vide temperature and pH control are all candidates for consideration in a plant's pollution control
program.
Pressure Methods Reduce Carrier Use. In view of the toxic nature and high-BOD potential of
dye carriers used in dyeing, it is relevant to point out the pollution advantage gained 'by the use of
pressure-dyeing techniques.
Ammonia May Help. Ammonia for use in desizing, scouring, bleaching, mercerizing, and dye-
ing of cotton is receiving considerable attention. There appears to be some justification on the sur- =
face for the use of liquid ammonia, but lack of information concerning product quality, equipment,
corrosion, toxicity, and so on, puts the justification for use of ammonia techniques in the early
developmental stage.
55
-------
unit being a scaled-up version of the laboratory unit represented in figure VI-4. One unit contained
mixed liquors seeded with 10 percent by volume of mixed liquors, taken by Blair Mills waste-
treatment plant, which was activated to biodegrade PVA. The feed to each unit comprised Cone
Mills' textiles waste containing starch to which 160 mg/1 of PVA was added. Operating conditions
for the tests are shown in table VI-6. These results confirm those for the lab-scale domestic
activated-sludge systems. (The unit seeded with mixed liquors acclimated to PVA showed excellent
removal [greater than 90 percent] of PVA within a few days.) This is represented by the line A-B
in figure VI-6. This high level of removal was maintained even after a 7-day interruption of the PVA
feed, indicating that treatment systems with long solids retention times in the aeration tanks will
remain acclimated during weekend and short holiday shutdowns.
In contrast, the removal of PVA in the nonseeded unit was much lower during the first 20 days
represented by line E-F in figure VI-6.
The conclusion to be drawn from this and other work is that PVA is apparently biodegradable.
If activated-sludge micro-organisms can be allowed to acclimate to PVA, it can be done under con-
ditions attainable in conventional waste-treatment systems, and over 90 percent of the PVA can be
removed.
Table VI-6.—Operating conditions for Cone Mills pilot-scale modified activated-sludge waste-
treatment units
Feed
BOD5 400-600
COD 700-1, 100
PVA 160 mg/l
pH 8-1 1
mg/l
mg/l
100
90
80
70
5 60
£
•S 50
| 40
30
20
IO
0
100
90
feo
I 60
4O
*n
Mixed liquors
MLSS 5,800 mg/l
DO 3-6 ppm
Liquid retention time 33 hours
Effluent
BOD5 4-8 mg/l
pH 8.2-8.5
Suspended solids 10-40 mg/l
:
-
o .. v v X .. „ .«X XV*C DX X v
B»^-x x " * x" K/ ""*
r . . /
/
•/.
* " * s*
x
f / * X Seeded unit
J . • • Non seeded unit
/A /E
:
X y X-XX S . VX
,r7-""-x*x^
- t ^f''~~~r*' '
-
x x
x x.
x
.
I X Seeded unit
• Non seeded unit
i i i i i i i i
0
2001
4OOJj
600
4O 5O
Time Dayi
60
80
C-O PVA feed interrupted.
Figure VI-6. Removal of PVA and COD in Cone Mills' pilot activated-sludge units.
62
-------
REDUCTION OF WASTEWATER FOAMING BY PROCESS-CHEMICAL SUBSTITUTION*
Introduction
One of the most commonly occurring problems associated with the treatment of textile dyeing
and finishing wastewaters is excessive foaming. In addition to being unsightly, foam generated during
treatment is usually a nuisance to plant operators and may be a frequent cause of complaints from
neighbors if blown about by strong winds. Furthermore, excessive foaming may seriously affect the
efficiency of wastewater treatment when biological processes, such as activated sludge, that require
a large amount of agitation and aeration are used. Interferences with treatment by foam may be
particularly critical during startup of a new facility. Presented here is the case history of a waste-
treatment situation in which excessive foaming problems had to be solved by in-plant process-chemical
change before reliable operation and treatment could be accomplished.
The situation occurred at the United Piece Dye Works plant located at Edenton, North Carolina.
The Edenton plant discharges about 1 million gallons of wastewater per day from the dyeing and
finishing of synthetic fibers. The wastewater is ultimately discharged to the Chowan River, a large
estuary.
The Facilities
In an attempt to provide treatment in compliance with pollution-control regulations, an
extended-aeration activated-sludge system was designed and installed. The system consists of a large
aeration lagoon with a capacity of 3.25 million gallons, followed by a sedimentation basin equipped
with sludge return facilities. The circular aeration lagoon has a 220-foot bottom diameter, a liquid-
depth of 10 feet, and sides with a 1 to 1.5 slope. It is equipped with floating, mechanical aerators,
and the bottom is sealed with an impermeable, rubberized material. The aeration horsepower ratio
in the lagoon at the present time is 135 horsepower per million gallons.
The Problem
When first put into operation, the system had an aeration horsepower ratio of only 44 horse-
power per million gallons,- much too low to keep significant concentrations of biological solids in
suspension. As a result, it was not possible to maintain a lagoon MLSS concentration of more than
350 mg/1, much lower than the 1,500 to 2,000 mg/1 needed for proper operation of an activated-
sludge system. Consequently, the system performed like an aerated lagoon with a short detention
time and a small amount of effluent recycle. In the detention time provided, the low solids con-
centration was able to achieve a BODS removal efficiency of only 55-65 percent, considerably short
of the 85-percent removal required by the State regulatory agency.
As soon as it was recognized that the poor treatment efficiency resulted from the inability of
the system to maintain high concentrations of biological solids in suspension, four 75-horsepower
aerators were added to the lagoon, bringing the horsepower ratio up to the present level. Unfor-
tunately, the large increase in stirring and agitation greatly multiplied the quantity of foam gen-
erated during treatment. The lagoon was soon covered with a layer of highly stable, viscous foam
several feet thick. At first, it was thought that the large quantity of foam was just a temporary
annoyance that would steadily diminish as the biological solids in suspension increased toward the
desired level of 2,000 mg/1. When the average MLSS concentration jumped from a little more than
300 mg/1 to more than 600 mg/1 the first month, it seemed certain that the foaming problem would
be short lived. However, 2 months later, the data showed that the MLSS had not only failed to in-
crease further, it had decreased to an average of slightly more than 400 mg/1.
*Prepared by Clifford W. Randall of Virginia Polytechnic Institute, Blacksburg, Va.
63
-------
Table VI-9.—Economic comparison
Chemical
Original chemicals:
Tar remover SW
Tanavol
TSPP
Total
Substitute chemicals:
Tanaclean HFP
Carolid A.L.
Soda ash
Total
Unit
cost,
cents/I b
25.5
42.0
11.0
27.5
36.0
4.0
Applied
dosage
3.3 cc/l
1.0cc/l
1.0gm/l
1 .0 cc/l
1.0 cc/l
0.3 gm/l
Quantity
per batch
20.0 I
6.0 I
6.5 Ib
6.0 I
6.0 I
2.0 Ib
Cost per
batch
$5.10
2.54
0.715
8.355
1.67
2.18
0.08
3.93
improved quality control or the improved wastewater treatment would have justified an increase in
chemical costs, but in this case, the change*was advantageous from all standpoints.
66
-------
Chapter VII
PRETREATMENT OF TEXTILE WASTES*
INTRODUCTION
Pretreatment
Pretreatment is defined as operations performed on a waste stream to make it suitable for in-
troduction into another waste system for further treatment. In most instances, the receiving system
is a publicly owned municipal or regional sewage-treatment system, but it also may be a private
system owned and operated by a mill or group of mills.
The major reasons for pretreatment follow:
• Protection of the treatment process to insure maximum efficiency
» Protection of the receiving system, its structures, and components from damage
• Protection of the health of the public and particularly of the sewage-system personnel
« Satisfaction of legal requirements listed in the local sewer ordinance, State laws, or Federal
laws
9 Reduction of treatment costs due to industrial-user surcharges
The first three reasons for pretreatment are for protection of the process, the system, and the
public. Usually the legal requirements in the local, State, and Federal laws are designed to insure
such protection. Consequently the degree of treatment and pretreatment necessary will usually be
indicated in the laws.
Local Sewer Ordinance
To qualify for Federal funds, municipalities must have a local sewer ordinance. Most duplicate
the model ordinance suggested by the Water Pollution Control Federation in the Manual of Practice
No. 3.1 Many municipal ordinances specify limits for pH, BOD, grease, total solids, and other
parameters that textile wastes may exceed, especially after reduction in water use. However,
Article V, Section 10, of the WPCF Manual of Practice No. 3 allows special agreements for the dis-
charge of such wastes. Industry should make certain that this section or its equivalent is part of
such ordinances when they are enacted.
SEWERAGE-TREATMENT SYSTEMS
The basic component parts of a sewerage-treatment system involve (1) a conveyance system to
transport the waste to the treatment system and (2) the treatment system itself. The treatment
*Prepared by Joseph W. Masselli, Nicholas W. Masselli, and M. G. Burford of the Industrial Wastes Laboratory,
Wesleyan University, Middletown, Conn.
67
-------
system is usually composed of a primary portion, which prepares the sewage for biological treatment
in the secondary portion of the plant. The component parts of each portion of the system may con-
sist of the following:
• Conveyance system: Pipelines, manholes, wet wells, pumping stations
• Primary-treatment portion: Bar screen, comminutor, grit chamber, preaeration tank,
primary settling tank with scum removal device and bottom sludge pumps
• Secondary-treatment system: Aeration tank (or trickling filter), secondary settling tank with
sludge-return pumps, chlorination detention tank
• Sludge-handling system: Thickening tanks, anaerobic digestion tanks, aerobic digestion
tanks, elutriation tank, filter or centrifuge, incinerator. (The raw sludge, the digested sludge,
and the activated (or trickling-filter humus) sludge may be handled separately or mixed
together.)
In recent history, the activated-sludge process has become the method of choice for waste
treatment. Discussions in this chapter are limited to this method unless otherwise indicated.
Occasionally the trickling filter may be used for treatment, but its reduced efficiency during cold
weather may cause trouble in meeting future effluent requirements.
POTENTIAL EFFECT OF TEXTILE WASTES
Some of the potential troublemaking sources in textile wastes are listed below:
• Lint, rags, fibers, strings
• Scum
• Foam
• pH
• Alkalinity
• Acidity
• Oxidizing agents
• Reducing agents
• Excessive flow
• Excessive BOD
« "Hidden" BOD's
• Hydrocarbon solvents
e Metals
• High temperature
68
-------
• Nutrients
• Nitrates
• Spurious biomass (MLSS)
• Dump discharges
Lint, rags, fibers, and strings will clog pipelines, pumps, and moving machinery. In addition,
short fibers will pass through the secondary system and occasionally rise to form scum in the
secondary settling basin. They also may be collected in foam and cause sticky, odorous deposits
along the sides of the aeration tank and the effluent channels.
Scum may cause unsightly stains, odorous conditions, may reduce oxygen transfer and may be
difficult to incinerate. It may be formed from soaps, greases, oils, solvents, and resin finishes.
Foam may be produced by both nonbiodegradable and biodegradable detergents. Some foams
are unstable and will be readily reduced by water> sprays, but others may require special defoaming
agents. If not reduced, foam may cause unsightly stains and odorous deposits, and may be blown
by the wind to nearby equipment, buildings, and homes.
Acidic pH's below 5.5 should never be allowed in sewage systems, since the cement, concrete,
mortar, and metals in the pipelines, manholes, wet wells, pumping stations, pumps, and treatment-
plant structures may be corroded. In addition, acidic pH's may deemulsify soaps, fats, and greases
to produce sticky gums, which may cause pipe blockage or scum formation. Bicarbonate alkalinity,
which usually buffers the pH in the 6.5-8.0 range, will be destroyed, and hydrogen sulfide odors may
be intensified if sulfide is present. The pH may be readily adjusted to the 6.5-8.5 range by the
addition of lime, caustic soda, soda ash, or ammonia.
Effluents from cotton- and wool-finishing mills are traditionally highly alkaline in the pH 10-
14 range because of the use of caustic soda in cotton scouring and mercerizing and soda ash in wool
scouring and fulling. The activated-sludge process can satisfactorily treat alkaline wastes, since this
process oxidizes the organic carbon in the waste to carbon dioxide. The carbon dioxide reacts with
water to produce the acidic carbonic acid; this neutralizes the alkalinity in the waste. Regulation of
the waste pH to 6.5-8.5 thus becomes automatic and is being continuously demonstrated by the
results from many activated-sludge plants treating textile wastes throughout the country. Probably
the only time neutralization may be necessary is when no attempt is made at caustic recovery in
mills mercerizing a great percentage of their cloth. It is believed that only 1 mill in 100 may need
pretreatment for alkalinity. In some instances, the oxidizing and reducing agents in textile wastes
may mutually destroy each other.
Excessive hydraulic flows will cause low detention times in treatment and will cause sludge
drag out into the aeration tank and into the final effluent.
Excessive BOD loads will produce zero dissolved oxygen in the aeration tank, and bulking sludge,
anaerobic odors, and high-effluent BOD's will result. These "shock" BOD loads may come from
dump discharges of high-BOD baths at the end of a run, a shift, a week, or before vacation. Occa-
sionally, processing changes, such as the use of xylene or Varsol in scouring, may cause excessive
increases.
Many chemical compounds are apparently nonbiodegradable or slightly biodegradable in the
BOD 5 test, but are readily biodegraded by the acclimatized bacteria that develop in the activated
sludge after continuous contact with these compounds. In many instances, the actual oxygen
demand exerted in the aeration tank will be 10-100 times greater than the demand estimated from
69
-------
the BOD5 test. If appreciable amounts of such chemicals with "hidden" BOD's are present, the
oxygen demand may exceed the aeration capacity of the system. Some of the compounds with
hidden BOD's are cellulose, polyacrylic acids, polyvinyl alcohol, naphthalene, and alkyl benzene
sulfonate detergents.
Hydrocarbon solvents are composed of carbon and hydrogen solely and represent a concen-
trated source of BOD. Their BODS 's are usually 20-100 percent of their own weight, but their
theoretical-oxygen demand of 300 percent may be exerted when acclimatized bacteria are present.
A 50-gallon drum of such a compound may weigh 400 pounds and exert an oxygen demand of
1,200 pounds in the aeration tank. This contrasts sharply with the average demand of 2-3 pounds
per 1,000 gallons for textile wastes. The use of these solvents should be reduced to the lowest
amount possible.
Toxic metals (copper, zinc, chromium) are normally used at low levels in textile processing.
These are concentrated in the activated sludge at 20-100 times the influent concentrations. Acidic
pH's may cause some bacterial kills, since dissolved metallic ions are more toxic than the insoluble
metallic hydroxides and carbonates normally present.
High temperatures above 95° F are reported to produce dispersed growths and lower BOD
efficiencies.2 The likelihood of such temperatures will be increased when water use is reduced, and
heat reclamation by heat exchangers should be used.
Nitrogen (N) and phosphorus (P) are nutrients required for proper bacterial growths, and
BOD:N:P ratios of 100:5:1 are usually recommended. Sufficient phosphate is usually present in
most textile wastes, but occasionally ammonia nitrate or another nitrogen source may have to be
added.
Nitrates above 22 mg/1 in the effluent may be reduced to nitrogen gas and cause rising sludge
and scum in the secondary settling tank.3
The concentration of activated sludge in the aeration tank is usually maintained at 1,000-3,000
mg/1 and is measured by the suspended-solids test. It is normally composed of bacterial bodies
(biomass) with 85-95 percent volatile matter and 7 percent nitrogen on a dry basis. Fine sand,
metallic hydroxides, paper, textile fibers, and other insoluble organic and inorganic matter will also
be measured by this test. If they are present in adequate amounts, they may produce spurious
biomass values. Insoluble fibers, paper, and organic compounds will produce spurious volatile
matter values, and wool fibers, which have a nitrogen content of 16 percent, will produce spurious
nitrogen values. Such sludges will have minimum purifying values, and an inexperienced operator
using only the suspended-solids test will not be aware of this.
In spite of the great list of potential troublemaking sources, textile wastes will be efficiently
treated by the activated-sludge process when proper design and loading is observed and BOD reduc-
tions in the 85-90 percent range can be readily obtained.
PRETREATMENT METHODS
Following is a description of the unit processes having application in pretreatment of textile
wastewaters.
Screening
The primary reason for screening is prevention of clogging of the pipes and pumps and also of
the comminutors, degritting, skimming, and scraping mechanisms in the system. The major causes
70
-------
of such clogging are rags, strings, or ropes, but individual fibers of 1-2 inches may gather together to
form balls or mats, which also clog pipes.
A secondary reason for screening is to remove the bulk of short fibers, since these will pass
through primary settling and the aeration tank. In some instances, these small fibers may rise to. the
surface in the secondary settling basin to form mats or scum, or they may pass through into the final
effluent to produce increased suspended-solids concentrations. They also may adhere to the side of
the tanks or clog the aerators.
In many mills, screening may not be necessary if ordinary care is tanken to prevent discharge of
the rags, ropes, and strings. The few pieces that escape may travel without trouble to the treatment
plant and will be removed by the bar screen, which is normally a part of all treatment plants.
If trouble occurs, a bar screen may be installed at the mill. One bar screen with 1- to 2-inch
openings is usually satisfactory.
If a considerable amount of fibers are present, screening with finer mesh screens will be neces-
sary. In most instances, 40-80 mesh openings will be satisfactory. The screens may be woven wire
or perforated plates and may be stationary, rotary, or vibrating. Mechanical brushes may be used
for fiber removal. j
pH Regulation
Pretreatment for pH neutralization of acidic ^wastes (pH's lower tnan 5.5) will usually be re-
quired, primarily to prevent corrosion. This may be readily done by the addition of lime, sodium
hydroxide (caustic soda), ammonia, sodium carbonate, sodium bicarbonate, or trisodium phosphate.
Generally, additions of only 0.25-1.0 pound per 1,000 gallons of effluent (30-120 mg/1) will be
needed to raise the pH to the 6.5-8.5 range. If nitrogen addition is required for nutrient value,
ammonia should be used, as it will provide both alkalinity and nitrogen. If phosphorus is requked,
trisodium phosphate should be used.
Increased use of alkaline chemicals in the processes will also regulate the pH. When possible,
it should be done to maximize use of the chemical as described.
Acidic effluents were rarely encountered in textile finishing until the advent of polyester knits.
When large proportions of knits are being dyed, the acetic acid used in dyeing may produce final
effluents in the pH 5.0-6.0 range. Mills with acidic pH's should consider doing some cotton finish-
ing, since the use of sodium hydroxide in scouring and mercerizing will supply the necessary
alkalinity.
The simplest means of increasing alkalinity is to pump a concentrated alkaline solution into a
drain as far from the effluent end as possible. Controlled dribbling, by means of a constricted valve
or pinched rubber tubing, may also be used. A 50-percent caustic-soda solution contains 762,700
mg/1 sodium hydroxide (952,000 mg/1 CaCO3). Only 63 gallons will be needed to add 60 mg/1
CaCO3 alkalinity to 1 million gallons of effluent. The concentrated ammonia solution (57.6 percent
NH4OH) contains 251,400 mg/1 ammonia (740,000 mg/1 CaCO3). Only 81 gallons will be needed
to add 60 mg/1 alkalinity (and 17 mg/1 ammonia nitrogen) to each million gallons.
Dry lime is the cheapest source of alkalinity, but it must be carefully handled, since the fine
powder may be blown all over the premises. Addition of 280 pounds per million gallons will add
60 mg/1 alkalinity.
If desired, special neutralization facilities may be constructed. This usually involves a tank or
flume allowing a 5- to 30-minute detention with a pH meter controlling the alkali addition. The same
controls may be used at an equalizing basin or a primary settling basin if they are part of the system.
71
mill processes. On Saturday and Sunday, all of the BOD would be from the desize process.
The flow from the mill would be 2.5 mgd on Monday through Friday, but only 35,700 gpd on
Saturday and Sunday. If necessary, some effluent may be pumped back to the head end of the
plant to preserve hydraulic flows.
In some instances, the mill may wish to build its own activated-sludge treatment plant to treat
the concentrated waste and discharge its effluent into the municipal sewer. With concentrated
wastes, higher BOD loads of 200 lb/1,000 ft3 /day may be treated, and a much smaller plant may be
used. For the 150,000 gallons and 30,000 pounds of BOD produced per week, a plant designed for
21,400 gallons and 4,285 pounds of BOD per day must be constructed. At a loading of 200 lb/1,000
ft3/day, an aeration tank of 21,400 ft3 (160,000 gallons) would also provide a detention time of
7.5 days. Such a plant should reduce the BOD by 90 percent; the remaining 10 percent (428.5
pounds) would be discharged to the municipal sewer. With this plan, the new mill effluent would
be 2.5 mgd with 4,429 pounds of BOD on Monday through Friday and 21,400 gpd and 429 pounds
of BOD on Saturday and Sunday. The design-BOD load has thus been reduced 56 percent and the
aeration-tank volume and the aeration equipment of the municipal-treatment plant may be reduced
accordingly. In addition, capital cost charges and operating charges will be reduced to provide a net
savings.
Other means of disposing of the concentrated wasteis should also be considered, as should the
economics involved. Some of the possible methods are as follows:
• Incineration at municipal incinerator or company boiler
-------
Equalization
Equalization—the process whereby the volume or the analytical content of the waste may be
discharged evenly throughout the day—may be necessary when batch discharges, intermittent rinsing,
or intermittent operation produce wide variations in flow or analytical content. All treatment plants
will operate more efficiently if the hydraulic, BOD, and other loads are constant throughout the
week.
Optimum equalization may be achieved by discharging all wastes into a pond, lagoon, or tank
whose volume is equal to the mill's daily flow. In this manner, a 24-hour detention will be provided,
and the analytical contents will be leveled out. If there are wide flow variations, a flow-equalizing
method must be devised to prorate the discharge rate. This may be done by means of pumps,
siphons, valves, or combinations of these. In most mills, tanks providing only 3- to 8-hour detention
times will provide sufficient equalization. In many mills, continuous-processing methods are being
used, and equalization will not be necessary. ;
The major reason for equalization is usually to level the BOD loads. In addition, if the major
part of the BOD is being contributed by only one or two washes, only these need be segregated at
the source of discharge and stored in much smaller equalizing tanks for discharge over 24 hours and
7 days. This is practicable for the desize and scour wastes in cotton mills, the scour and wash after
fulling hi woolen mills, and the knitting-oil scour in polyester-knit mills. Usually, segregating a
volume equal to only 1-3 percent of the total mill flow will provide equalization of 50-90 percent of
the total BOD. Specific methods of equalizing are indicated below under "BOD Reduction."
Equalizing lagoons with detention times greater than 1 day are likely to develop odor problems
through anaerobic conditions and the resultant evolution of hydrogen sulfide. This has been known
to occur even when the effluent pH is in the 11-12 range. Deep pockets, which collect sludge, will
• Evaporation followed by incineration
• Reuse in processing
• Reuse as another product
• Treatment by chemical coagulation
• Treatment by chemical oxidation with chlorine, peroxide, permanganate, or ozone
• Treatment at high temperatures and pressures
• Treatment by ion exchange
• Treatment by reverse osmosis
• Anaerobic digestion
Some mills may be situated near regional incinerators that are large enough to handle the con-
centrated waste after it is sprayed evenly on the solid waste.
In order to reduce transportation costs, evaporation should always be considered to further re-
duce the volume. The 30,000 gallons of concentrated desize waste may be evaporated down to
7,500 gallons. Therefore, only one trailer tank truck will be needed instead of four to remove the
waste from the mill.
Evaporation followed by incineration should also be considered, especially when the waste con-
tains more than 6,000 mg/1 BOD. Each 1,000 gallons contains 50 pounds of BOD.
Occasionally a concentrated waste may be reused within the mill for the same process or another
process. All supervisors should be notified of the waste and its exact contents and asked to look into
rinse possibilities.
Other industries may also be able to use the waste and all possibilities should be continuously
reviewed. The high starch-sugar content of the desize waste makes its use for animal foods or alcohol
fermentation highly likely. Wool grease may possibly be used for lanolin production or rust-
prevention products. The waste and its analysis should be submitted to all likely users.
In some instances, chemical coagulation of the concentrated waste may provide adequate BOD
reductions. It may not be used with the desize waste, since sugar is soluble and will not be pre-
cipitated. Wool grease and soap may be precipitated by calcium chloride, especially when treated
to 140°-180° F, to produce BOD reductions of 70-90 percent.4 The knitting and coning oils in the
polyester-knit scour waste are present in colloidal emulsion, but these may be precipitated by the
common coagulants. The disposal of the sludge from these treatments would be a problem.
Treatment by chemical oxidation or at high temperatures and pressures have been successful for
some wastes.
Treatment of organic wastes by ion exchange is seldom done and would not be useful with
these wastes. Reverse osmosis may be useful, but the brackish water left as a waste would be
difficult to dispose of.
Anaerobic digestion could be used with these wastes if a large municipal digester is available.
Normally, the digester may be loaded at 100 Ib BOD/1,000 ft3 /day if properly stirred. For the
-------
desize waste above, a tank with 60,000 ft3 (450,000 gallons) would be required, providing a deten-
tion time of 15 days. The waste would produce approximately 50,000 ft3 /day of methane gas,
which may be used to maintain the tank at 90° F for proper digestion. The moderate amounts of
sludge produced could be disposed on agricultural lands or in landfills.
COD
It should be noted that COD, total oxygen demand, and TOG are rapid analytical measures of
organic matter and are used in conjunction with the slower BOD determination. Consequently, the
same procedures indicated above for BOD removal are used for COD removal.
In some instances, there may be adequate BOD removal but inadequate COD removal, indi-
cating that soluble or colloidal nonbiodegradable organic matter is present in the waste. If further
COD removal is required, all efforts to identify the nature of the compounds contributing the COD
should be made, and biodegradable process chemicals should be substituted for the nonbiodegrad-
able compounds. If this is not possible, treatment by chemical coagulation or activated carbon will
have to be used, and costs will be doubled or tripled.
Chromium Removal
Chromium is usually used for oxidation in cotton and synthetic dyeing and for chemical fixa-
tion in wool dyeing. Usually, sodium dichromate, the hexavalent or oxidized form of chromium, is
used, and a small percentage of chromic (trivalent) chromium is produced on reduction. The
hexavalent form is yellow and soluble at all pH's, ivhile the trivalent form is greenish and insoluble
at pH's above 6.5.
In cotton and synthetic dyeing, other oxidants (peroxide, air, stream) may be used in place of
the dichromate, and complete chromium removal may be obtained.
In wool dyeing, excessive chrome add-ons are often used. A considerable reduction in effluent
chromium concentrations may be obtained by reducing the add-ons.
When removal is desired, the soluble hexavalent chromium must be reduced to the insoluble
chromic chromium. This may be done with sodium metabisulfite at pH's below 4.0 or with
copperas (ferrous sulfate) at any pH. When concentrations are below 50 mg/1, copperas is preferred.
Treatment directly at the source is preferable, sinqe the concentration in the effluent of most mills is
very low, usually below 2.0 mg/1. The sludge may; be removed by chemical flotation or by sedimenta-
tion in a tank providing 1-2 hours' detention. When copperas is used, a final pH of at least 8.5 is re-
quired, since the ferrous iron is soluble at pH's below that. With bisulfite reductions, a pH of 6.5-9.0
is satisfactory.
Phenolics
Phenolics indicate chemical compounds containing the phenol structure. Low concentrations
in the parts-per-billion range may cause off-tastes in drinking water after chlorination or in fish.
Many process chemicals, including some detergents, have this structure as part of the molecule, but
the major source is probably the phenol used in the phenol-formaldehyde resin used for final
finishing. The only discharge from the final finishing process is the excess solution left in the pad
or impregnating trough. This should never be dumped to waste. It may be sprayed on the waste-
paper or wood collected in the mill and incinerated.
75
-------
Activated sludge will oxidize most of the phenolics if the associated chemical structure is not
too complicated, but the rigorous treated-effluent guideline concentrations may still be exceeded.
When this happens, a process-chemical survey may reveal the probable source, and treatment or
process-chemical substitution should involve the point of origin. Chemical coagulation or oxidation
with potassium permanganate may be useful in removing these compounds.
Sulfide
Sulfide usage in textile processing is very low, and sulfide is never present in most mill wastes.
If present, the pH should be kept in the alkaline region of 9-10 to prevent the volatilization of the
very odorous hydrogen sulfide. The activated-sludge process will readily oxidize sulfide to sulfate.
Generally, the presence of sulfide will be no problem. The major source of trouble will be produc-
tion of sulfide odors in the lateral lines to the sewage plant if acidic pH's are produced by other
wastes in the system.- If desired, sulfide may be oxidized by hydrogen peroxide, chlorine, hypo-
chlorite, or potassium permanganate.
O i I, G rease, and Soap
Oil, grease, and soap are usually emulsified and readily treatable in the activated-sludge process.
In some instances the emulsion may be broken, and scum and sticky deposits may form. Soap and
vegetable oils are readily biodegradable, but the coning and knitting oils used for wool and poly-
ester knits may on occasion be nonbiodegradable mineral oils. The latter may possibly reduce oxygen
transfer in aeration and contribute high COD's in the final effluent.
If pretreatment is to be done, it probably should be done at the source. This will usually in-
volve the wool scour and the first portion of the wash after fulling in woolen mills, and the first
scour in polyester-knit mills.
The segregated concentrated wastes may be evaporated and incinerated or they may be treated
by chemical coagulation with calcium chloride at 120°-140° F or with the common coagulants.
Chemical flotation for sludge recovery may prove more satisfactory than sedimentation. The waste
sludge should be incinerated.
It is believed that pretreatment for these substances will not be required unless floating oil or
grease is obviously present in the waste.
Detergents (MBAS, ABS, LAS)
Detergents are usually measured by the methylene-blue test as methylene-blue active substances
(MBAS) and may be composed of alkyl benzene sulfonates (ABS), normally considered as nonbio-
degradable, and linear alkyl sulfonates (LAS), normally considered as biodegradable. The nondegrad-
able ABS compounds are no longer manufactured for general detergent use, but they may be used
in some textile operations in which a considerable portion may pass through the activated-sludge
treatment process. When reductions are required, the most practical way is to trace the source
(e.g., through a process-chemical inventory survey) and eliminate its use by substituting a biodegrad-
able LAS detergent or even soap.
Chemical coagulation with the common coagulants may be useful, but costly, and should be
tried if necessary. When possible, only the major source of the detergent may have to be treated to
provide adequate reductions.
76
-------
Color
: If required, color removal will probably be the greatest problem in textile-waste treatment,
since it can be attained only at great cost in most instances. Unfortunately, determination of color
i in textile wastes is a complicated analytical process, and information on color is seldom included in
textile-waste surveys.
A fairly simple test to estimate the approximate color content of a waste is to'determine the
dilution with tap water (or stream water) necessary to reduce the color to extinction. If a dilution
'• of 50 times were necessary, the sample was considered to have a dilution to extinction (DTE) of
1 SOX. If there were 20,000 gallons of the waste, the total color units produced by the waste would
be considered to be 20,000 X 50, or 1 million color units. In this manner, the relative number of
1 color units from the various sources could be estimated, and the major sources of color could be
; identified. In one commission house, the fugitive colors in the desize waste (25,000 gal/day) pro-
duced a DTE of 600X and a total color of 15 million color units. The mill also dropped 100,000
; gallons of exhausted concentrated dye baths with a DTE of 150X and a total color of 15 million
: units. The major source of color, however, was caused by the batch dumping of the waste print
! pastes from the color shop. These pastes had a very high, color content with DTE's of 30,OOOX-
600,OOOX (average 80,OOOX). The mill dumped 400 gallons per day, producing 32 million color
units. The print pastes thus contributed 52 percent of the total color, and the dye baths and the
' desize waste each produced 24 percent each. Subsequent investigations have indicated that many
printing mills waste as much as 1,000-2,000 gallons of print pastes per day, and color contribution
by the batch-dumped pastes may amount to 60-80 percent of the total color. It is obvious that the
I waste-print pastes should never be dumped into the effluent. Segregation and separate disposal of
! only 400-2,000 gallons per day will produce an immediate color reduction of 50-80 percent. In the
: mill, the pastes are sprayed on the solid wastes at the local incinerator.
I When color removal is required, all means of reducing the color in the waste must be used.
1 This may involve the following:
• Segregate all waste-print pastes, if any, and dispose separately in landfill, ocean, or incinerator.
• Reduce losses in the color shop by careful hand cleaning of all brushes, troughs, doctor
; blades, cans, tanks, and screens.
i • Attempt to get weaving mills to reduce the use of fugitive tints in weaving.
; • Try to exhaust the dyes more thoroughly in the dye process.
• Use dye processes that cause less color loss, for example, solvent, pad-and-steam, microfoam,
i methanol, and ammonia dyeing.
Following this, only the concentrated color wastes should be segregated and treated, as this
may possibly produce enough color removal to satisfy the requirements. This will usually involve
1 the exhausted-dye baths and the color-shop wastes (cleanup, wash after printing, and blanket wash).
i These may be treated with chlorine, hydrogen, peroxide, potassium permanganate, sodium bisulfite,
• or chemical coagulation with the common coagulants (ferric, ferrous, and aluminum sulfates or
chlorides and/or lime).
: If adequate removals are not obtained, the treated effluent may be further treated by passage
through a granular activated-carbon filter. Usually, however, prior passage through a sand or mixed-
media filter is necessary to prevent clogging of the carbon.
; If the uncollected rinses contain too much color, the entire mill effluent will have to be treated.
77
-------
Phosphate
In some instances, phosphate removal may be required. If so, it may be more readily done by
substituting nonphosphate chemicals such as ethylene-diaminetetraacetic acid and others for the
phosphates normally used. If treatment is necessary, phosphate may be readily reduced to below 1
mg/1 by chemical coagulation with ferric, ferrous, and aluminum salts or with lime.5 The coagula-
tion may be done before, after, or even in the aeration tank of the activated-sludge process.
Nitrogen
Nitrogen in wastes may occur as ammonia, nitrite, nitrate, or organic nitrogen. In biological
oxidation, ammonia may be converted to organic nitrogen in the bacterial bodies and to nitrites and
nitrates. The organic nitrogen may be removed as sludge, but the unconverted ammonia, nitrite,
and nitrate are soluble and will be present in the effluent. In some cases, oxidation of the ammonia
in the stream may deplete the oxygen resources in the stream, since ammonia has a very high potential
oxygen demand of 423 percent.6 In addition, ammonia has a very high chlorine demand and may
raise chlorine use for disinfection to high levels. This may also tend to make the effluent toxic to
fish because of the chlorinated amines produced.7
Ammonia removal may be accomplished in two ways. Carbonaceous BOD such as methanol
may be added to the aeration tank to convert the excess ammonia to organic nitrogen as bacterial
bodies and removed as sludge.8 It also may be removed by raising the pH to 9-11 with lime or
sodium hydroxide and aerating the mixture to gasify the ammonia.9
Nitrites and nitrates cause problems since they may be denitrified by certain bacteria to pro-
duce nitrogen gas, which causes sludge rising in secondary settling basins. In addition, they may
cause excessive algae growths in the receiving stream. They may be removed by creating favorable
conditions for the denitrification process, described above, to occur.9
The best way to solve the nitrogen problem is to limit ammonia, nitrite, and nitrate use hi proc-
essing. If such use is fixed to produce a BOD:N ratio of 100:5, practically all of the nitrogen will
be converted to organic nitrogen and removed as sludge.
REFERENCES
1 Regulation of Sewer Use, Manual of Practice No. 3, Washington, B.C., Water Pollution Con-
trol Federation, 1968.
2 J. W. Masselli, N. W. Masselli, and M. G. Burford, "Factors Affecting Textile Waste Treat-
ability," Textile Industries, 135, 84, 1971.
3 T. W. Brandon and S. Grindley, "Effect of Nitrates on the Rising of Sludge in Sedimentation
Tanks," Sewage Works Journal, 17, 652,1945.
4J. A. McCarthy, "A Study on Treatment of Wool Scouring Liquors," Sanitalk, 3, 17, May
1955.
5 U.S. Environmental Protection Agency, "Process Design Manual for Phosphorus Removal,"
Washington, D.C., EPA Technology Transfer, Oct. 1971.
6 J. W. Masselli, N. W. Masselli, and M. G. Burford, "BOD? COD? TOD? TCC?" Textile Indus-
tries, 136, 53, 1972.
78
-------
7 Anonymous, Chemical and Engineering News, Apr. 23, 1973, p. 36.
8 "Cleaning Our Environment. The Chemical Basis for Action," American Chemical Society
Report, p. 133, Washington D. C., 1969.
9 Carl E. Adams, Jr., "Removing Nitrogen from Waste Water," Environmental Science and
Technology, 7, 696, 1973.
79
-------
-------
Chapter VI11
SUMMARY
THE WASTE SURVEY, MAJOR SOURCES OF WASTE, AND FLOW REDUCTION*
In summarizirig and discUssing'the water-pollutionsubjectSj-the»two.main,±opics.aee.,c,xm:ent.,.,
technology and treatment-plant operation, as well as those future technological advancements or
changes to operation. This summary deals with those current practices in the technology of waste-
water treatment: the waste survey, major sources of waste, and flow reduction.
The Waste Survey
The waste survey provides a characterization: of wastewater, both from the effluent waste
stream and the individual contributing waste sources in the textile plant. The preliminary waste-
water survey gives a general overview of the wastewater problem, as well as basic design criteria for
wastewater-treatment programs. The whole integrated plan for the wastewater survey generates
preliminary.information for the design of wastewater-treatment-plant construction and provides the
necessary insight into the wastewater-treatment process so that manufacturing process changes can
be adequately anticipated as they affect the effluent quality.
The preliminary waste survey deals with obtaining knowledge concerning the volume of waste-
water required and fluctuations in daily requirements. It is concerned with a determination of the
wastewater characteristics in terms of concentration or strength and the major in-plant wastewater
sources—their reduction and control.. The survey also deals with the environmental impact as the
treated waste effluent is discharged to the receiving stream.
The tools of the wastewater survey are the water/wastewater "budget," the manufacturing
operation, and a raw-materials survey. The water/wastewater budget is concerned with sources of
wastewater and collection of the effluent. Simultaneously with determination of the water-balance
quantities, sampling of the effluent sources are made. Both individual waste-source sampling and
analysis are performed, as are total effluent sampling and monitoring of discharge volume.
As a part of the waste survey, manufacturing operations and raw materials are to be included.
A materials balance can be developed for each line of the textile operation. These include the fabric
or textile products, the dyeing or finishing product, and the wastewater from each production unit.
The analytical work associated with the waste survey indicates that a substantial amount of labora-
tory analysis may be required. Depending on the quantity of effluent discharged, consideration
should be given to operating a wastewater-analysis laboratory at the textile plant. The cost can often
readily be justified by consideration of the cost of equivalent analytical work by outside, indepen-
dent laboratories.
The detailed waste survey follows the preliminary survey as a smooth transition from the basic
knowledge to the detailed data collected. The detailed survey can begin to be concluded after
approximately 1 year's collection of data. It serves to firmly establish design criteria and provide
better waste characterization. In a 1-year period, the detailed survey will show seasonal variations, as
well as production irregularities. The detailed survey should be a refinement of the preliminary
*Prepared by B. Thomas Hancher of the Institute of Textile Technology, Charlottesville, Va.
81
-------
procedures, that is to say, more precision in the water/wastewater balance. As with the preliminary
survey, the detailed survey should reflect waste parameters expressed in terms of pounds of
production.
The continuing monitoring phase of the survey serves as the firm basis for rational design of
wastewater-treatment systems. This continuing monitoring phase is the standard for operational
purposes and for purposes of comparing alternatives. Those alternates addressed here are variations
in production and in chemicals used in the textile process. When the continuing monitoring survey
permits in-plant monitoring, the results can be expressed in terms of each department, whose cost
expressed per pound of production includes pollutional load, flow, and overall treatment cost.
Major Sources of Waste ;
In a discussion of major sources of waste from textile operations, a classification or categoriza-
tion of the textile industry has been presented and described in eight general categories. In any
effort to describe the wastewater from the textile industry, only generalizations should be empha-
sized. The major wastewater characteristics have been given as a range of compositions that might
occur, and it has been impressed that pinpoint interpretations lead to errors in characterization of
the waste. Classical studies have indicated that textile production sources should be categorized
based on the predominant fiber of the three major categories: wool processing, cotton processing,
and synthetics processing. A description of both the BOD and the effluent quantity have been
given for each of these groups.
A further breakdown of the sources of wastewater gives a description of the pollutional charac-
teristics of the various processes. Included in the processes are the pollutional loading of dye carriers,
the breakdown of wool wet processes into individual operations, and a similar breakdown for cotton
and synthetic fibers. Discussions have been given of the effect of sizing different from starch and the
resultant reduction in BOD. However, looking beyond this one characterization indicated a possible
greater effluent concentration of COD. Variation in products that cause variations in the effluent
serve as one example of the need for consistent and continuous monitoring of the textile-wastewater
effluent. The variability apparent in the effluent is controlled substantially by compositing practices
in wastewater monitoring. Proper compositing produces effluent concentrations similar to that of
the actual waste stream. Without the benefit of composite waste samples, any sample concentration
may be considerably different from the actual waste stream.
Flow Reduction
Water savings is not a matter of pure academic importance but is a current practical necessity.
This need for effluent flow reduction is caused by higher costs and by the greater demand of
Federal and State agencies for wastewater-pollution control. This results in a greater incentive for
the textile plants to reduce their quantity of water flow.
Implementing a program of water conservation has been described and encompasses six ;
general actions:
• Stop the supply of water when production equipment is stopped.
• Reduce the quantity of water used to the minimum amount.
• Modulate the water supply depending on the speed of the textile products handled.
• Reuse nonchemical-treated cooling water by use of cooling towers for recycle.
82
-------
• Reuse chemical-treated water, since some textile processes do not require the high quality
of water that other units require.
• Utilize steam condensate return and reuse. Examples or case histories have been presented
showing 75-percent and 45 percent water conservation.
WATER REUSE, WASTE SEGREGATION, AND SUBSTITUTION
OF PROCESSES AND MATERIALS*
Before getting into the more sophisticated areas of control and regulation of waste output, it is
necessary that all the primary steps, discussed previously in chapter III, be taken. While on this
subject, it should be noted that before attempts are made to reduce flow, the actual magnitude of
the flow should be known with accuracy. In other words, the watermeter or meters into the plant
should be completely reliable. This may seem to be a very obvious point, but many plants seem
to have very little idea of their actual water consumption due to inadequate or faulty watermeters.
It is also .necessary that there be a knowledge of where the water use in the plant is taking place in
relation to particular areas, such as dyeing versus finishing, and whenever possible, in relation to
individual machines or ranges. This means that either flow meters or watermeters should be
installed in lines to machines or particular areas where this is feasible. Once a very accurate fix
has been obtained on exactly where the major areas of water use are, then work can be concentrated
on these areas toward a reduction in water use. Too much time is spent in trying to reduce water
consumption on machines and ranges that use quite small amounts of water. Efforts should be
concentrated where effort will be repaid. There is also the question of maximum water-use efficiency.
Different wash-box designs, of course, give different degrees of liquid interchange between bath and
fabric. Anything that can improve the balance and improve the efficiency of interchange will
enable the plant to cut back on the water usage on a particular operation.
Water Reuse
Much talk is heard today about the possibility of reusing water, and several operations are
reusing at least some of their various types of water that would otherwise be directed straight into
the effluent-treatment system. The simplest example of water reuse, and one that has been used for
quite a long time, is the counterflowing of wash boxes on a range. In a counterflow situation,
water is actually reused to a number of times equal to the number of boxes counterflowed. The
water from the last box, instead of being dumped, is reused in the previous box, and so on. This
is by far the most economical way of running a series of wash boxes, and it has no disadvantage
in washing efficiency over a range in which boxes are individually dumped. Thus, there seems to
be no reason, extending this principle, why water from "clean" processes cannot be reused in more
"dirty" processes. For example, water from bleach range wash boxes should be quite suitable
for making up desizing, scouring, or mercerizing liquors. Unfortunately, however, this type of
reasoning presupposes a fairly wide range of activities being pursued in one particular mill, and
this is not always the case. It also assumes either that output and product mix is fairly consistent,
or that an extremely flexible piping system can be1 installed.
After considering the reuse of process water in other processes, consideration should also be
given to the nonprocess water and its reuse, either in actual fabric contact processes or reuse again
as nonprocess water. Such water is, for example, condenser cooling water, water from water-cooled
bearings, heat-exchanger water, and the like. Here it can be postulated that not only water reuse
*Prepared by Dennis Balmforth of the Institute of Textile Technology, Charlottesville, Va.
83
-------
and savings will arise from this, but also the recycling of heat energy. Thus, heated cooling water
could be stored and reused in a dyehouse as process water already partially heated, reducing
dyehouse heating costs. One of the large water users in a yarn dyehouse is the water that is run
through the enclosed package drier condenser system to cool the air after it has passed through
the yarn packages, thus removing the moisture that it contains before reheating and recirculating.
There is quite a massive output of this water from a single unit. A typical figure might be IVz
million gallons per week. This could be recycled as process water.
Waste Segregation
Waste segregation is a rather complicated subject. Many people have talked about the
apparent foolishness of running more-or-less clear rinse waters together with concentrated pad bath
liquors into the same treatment facilities. The argument is why dilute a concentrated effluent and
make it more difficult to treat? But, what does one do with slightly contaminated water? It is not
feasible to set Up an entirely different waste-treatment facility for cleaner water. Here, perhaps,
there is a tie-in with the previous subject of water reuse. Water should not be discharged to the
waste facility until it is absolutely nonreusable for any purpose because of the amount of contaminant
it contains. Thus, dirty wastewater would be sent to the lagoons and more-or-less clean water
to the dirtier processes. This objective may not be within the reach of all of us, but the idea of
holding wastes of certain characteristics until such time as those characteristics are needed in the
lagoons is interesting and, given a sufficient amount of piping and a sufficient amount of tanks, would
seem to be quite feasible.
Substitution of Processes and Materials
One area that seems to hold out a great deal of hope for improvements in the waste situation
is that of substitution of processes and materials. Lists of a variety of textile chemicals with their
BOD values have been assembled. If there is a choice of two chemicals to use, the one with the
lower BOD is preferable. Similar reasoning applies to toxicity. However, in this area of substitution
of materials, it is not likely that a substitute will be found for the prime material: water. There
has been much recent talk about solvent processes, and 5 years ago it seemed that a whole new
textile technology was opening up. This early promise has not been fulfilled, except for special
processes, such as knit scouring and some finishing. There may be a future for solvents in desizing,
with the idea of recovery of solvent, soluble sizes, and reuse, although one would imagine that
this would probably mean a radical change in the greige mill so that the greige mill setup would
provide solvent desizing facilities at the mill and then reuse of the recovered size. As far as
bleaching and dyeing are concerned, it seems that solvent processing at present offers little
promise. The only dyes that readily dissolve in solvents that are suitable are disperse dyes. This,
of course, limits us to synthetic fibers and also even eliminates some of the better classes of dyes
for these fibers. Other dyes, such as water-soluble dyes for natural fibers, need to be dissolved in
mixed solvents or emulsions or complicated systems of this kind. This leads to a multitude of
problems in bath stability and solvent recovery as well as to problems relating to the constancy of
composition of the mixed bath. Another factor is that at present, dyes are sold either with
deliberately added or accidentally added diluents, most of which are insoluble in the solvents
considered for possible use in textile operations.
Thus, at least purer dyes need to be produced. Not many years ago, dye manufacturers
were promising ranges of solvent-soluble dyes, which would be applicable readily to most classes
of fibers. These ranges, needless to say, have not yet materialized. In order to be practical on
a large scale, it is necessary to advance to the stage where only one solvent for desizing, scouring,
bleaching, dyeing, and finishing is required. It would obviously be impractical in a complex
plant to have three or four different solvents being used for different operations, each with a
recovery unit.
84
-------
Thus far, the engineering problems relating to solvent processing have not been considered.
The figure often quoted as being necessary for economic feasibility is 98 percent recovery, and
many machinery manufacturers indicate that this level is possible with their equipment. However,
in the plant, the story seems to be a great deal different. Even at the 98-percent recovery level,
vast amounts of solvent will escape into the air from a large mill operation and lead to extremely
severe air-pollution problems, not particularly from the solvents themselves, perhaps, but from
-the products subsequently produced by actinic degradation. There are also the problems of
within-plant toxicity, and the Occupational Safety and Health Act (OSHA) here has restrictive
regulations. Even in a simple operation such as dry cleaning of knits with solvents, problems have
arisen due to spillage, inadequate engineering of recovery units, leaks in machinery, and the sucking
of fumes from the solvent units into the combustion zones of gas-fired tenters with resultant
production of acidic fumes and damage of fabric. Therefore, it seems that water will continue
as the prime medium for 95 percent of the textile operations for many years to come, and that
the greatest area for improvements lies in that of chemical substitution, for example, peroxides
and other per compounds being used in oxidation processes instead of metal-containing salts,
such as chromates, and polyvinyl alcohol instead of starch, along with low-foaming detergents.
PRETREATMENT OF TEXTILE WASTES*
If it can be shown that elimination of any substance that may have even the slightest ecological
significance can be economically achieved, pretreatment or elimination of its use may be ordered.
At the present time, very few mills have to pretreat their wastes to protect the treatment system or
process, although each mill will have to inspect its discharge thoroughly to make certain of this fact.
If pretreatment is necessary, it probably will involve screening for lint, fiber removal, or, less likely,
pH regulation of highly alkaline wastes from cotton mills using the mercerization process without
caustic recovery.
Many sewage-treatment-plant operators are fearful of accepting textile wastes for combined
treatment and may ask for excessive and often unnecessary pretreatment. They should be shown
the results from any of the many plants that are successfully treating these wastes without pH
adjustment or equalization throughout the country. In the next few years, the number of textile-
waste-treatment plants will increase many times, and a considerable amount of new data will be
available.
Many of the problems that may possibly be produced by textile wastes can be eliminated
through in-plant process or process-chemical substitution. This type of effluent modification
should be reviewed continuously. One of the greatest needs at the present time is an accurate
analysis of the process chemicals being used by the industry, since these chemicals produce 99
percent of the solids in all textile effluents (except;wool-scouring wastes). Each process chemical
should have the BOD, TOG, theoretical oxygen demand (ThOD), biodegradability, phenolic content,
ABS content, total solids, and metallic content on its label. In addition, the pollution potential of
each process suggested by the process-chemical manufacturer should be indicated in pounds of
BOD and ThOD per 1,000 pounds of cloth. The plant supervisor may then use the processes that
will cause less pollution and less pretreatment.
Weaving, knitting, and thread mills should provide exact information on the amount and type
of slashing sizes, lubricants, etc., on each product, and the BOD and ThOD loads that they will
produce when desized or scoured.
*Prepared by Joseph W. Masselli, Nicholas W. Masselli, and M. G. Burford of the Industrial Wastes Laboratory,
Wesleyan University, Middletown, Conn.
85
-------
The industry must thoroughly review the reason for use of each chemical and its impact on
pretreatment, treatment, ecology, and end disposal.
Methods involving the least color loss in printing and dyeing will be most important, since
color is readily noticeable and will be the cause of most future complaints by the public, in spite
of the fact that color has a minimal pollutional effect and is soon dissipated.
The use of soluble inorganic compounds that are difficult to remove (sodium chloride,
hydroxide, sulfate, bicarbonate, carbonate, etc.) should be reduced as much as possible. They
may be replaced by recoverable or disposable inorganics, such as ammonia or phosphate, or
possibly by biodegradable organic compounds. If reduced to low enough concentrations, the
possibility of recycling the activated-sludge effluent for reuse in the,mill may be greatly enhanced.
Whenever possible, discharge of concentrated wastes (above 6,000 mg/1 BOD) into water
should be avoided. Segregation and separate, disposal by reuse, new-product formation, evaporation
and incineration, anaerobic digestion, and other means should be investigated.
Waste-print pastes especially should never be dumped into water, since they not only contain a
considerable amount of BOD but they are the major color sources also.
Hydrocarbon solvent usage should be reduced to an absolute minimum, since they have very
high BOD's and only one or two barrels per day may contribute as much as 1,000-2,000 pounds of
BOD. In one mill, elimination of hydrocarbon use in print-paste makeup reduced the effluent
BOD load from 6,000 pounds to 2,000 pounds per day—a fantastic reduction through the elimination
of only one process chemical.
The simplified chemical inventory survey can be of great value in keeping track of loads and
in tracing trouble sources. It should be reviewed continuously in conjunction with production
charts. Each mill should know the approximate water use, BOD, and total solid and alkalinity
loads expected from the kind of processing they do and should make certain they are within the
usual limits. If not, they probably are using excessive add-ons or high-BOD chemicals.
It is highly probable that in-plant changes involving process or process-chemical substitution
will be used in place of pretreatment or treatment and will provide less expensive and more
satisfactory remedies when offending substances or qualities are present in the waste.
The only certainty about pretreatment is that the degree and nature of it will be changed
several times in the future when new and more specific information becomes available. Such
information will be increased tremendously in the next year or two, since all textile wastes will
now be treated and the required analytical results will become available for review. Research
projects on the compiling of such information should start immediately.
The determination of the nature, the amount, and the source of the residuals in all effluents
is of great importance and should be the object of future study. There is no doubt that industry
and society can do a much better job of protecting its stream resources than it has in the past.
86
-------
Part 11
AIR-POLLUTION ABATEMENT
-------
-------
Chapter I
THE EMISSIONS SURVEY*
One rarely embarks on an emissions survey without at least some notion of what to look for.
The usual question is not, What? but How much? Ignoring the well-known problems arising from
steam raising and waste incineration, the next most prevalent air .pollutants .that come from the-
textile industry are hydrocarbons. Finishing operations are especially culpable.
Thanks to certain pressures from the guardians of receiving waters, and to pronounced thermal
economies as well, there is a trend toward the use of hydrocarbon solvents for such steps as scouring,
dyeing, coating, and the application of fire retardahts, for example. (Pioneer issues of the Reviews
of Progress in Coloration may be consulted for examples.) Many of these solvents are, because of
their low photochemical reactivity, exempt from regulation as air pollutants. Trichloroethylene is
an exception in some jurisdictions.
A more severe problem arises from chemical reactions employed in resin finishing and bonding.
Reactions are sometimes an inadvertent, or at least inessential, result of high-speed thermal treat-
ments, such as flame laminating. There is always the urge to raise the temperature in order to process
more goods, whereupon simple softening turns toward scorching. What makes these problems severe
is the often unknown nature of the reaction products and the difficulty of predicting or even con-
trolling their rates of production. Compounding this difficulty is the special pollutant category in
which such products are placed. The language of the law refers typically to "baked, heat-cured, or
heat-polymerized" goods and, in the tradition of the celebrated Rule 66 of the Los Angeles County
Air Pollution Control District, the emissions to the air of byproducts from goods so processed are
limited to 15 pounds per day.
An intermediate case creates a special problem. Polyester knits are heat set or "tentered," for
reasons of fiber mechanics, but often as well to drive off the heavy organic carriers used in disperse
dyeing. Conditions are severe enough that low-molecular-weight fractions of the polymer are
evaporated; these, with or without dye carriers, are then emitted to the atmosphere where they con-
dense into an oily fog, the "blue haze." Such an emission is mechanically an aerosol; it is subject to
regulation as a visible emission, as a particulate. But chemically, it is a hydrocarbon, and some of
the carriers are on the list of hazardous materials recognized by OSHA. Perhaps, it can be argued
that the source of these emissions is not "heat-curing" in the spirit of Rule 66.
These, then, are the principal sources in the textile industry, again excepting steam raising
and waste incineration. !
It may not be clear why all hydrocarbons—even some that cannot be smelled and have no direct
consequences to human health—should come under regulation. And how does it happen that the
several States, responding to uniform guidelines for the preparation of implementation plans,1 should
emerge with so variable a group of regulations? ;
A close reading of the guidelines reveals that regulations affecting the emission of hydro-
carbons are almost exclusively concerned with their contribution to the problem of photochemical
oxidants, which are a direct menace to human health. The problem is occasionally so bad in Los
Angeles that school children are forbidden to go outside and play at recess time. It follows that
*Prepared by David B. Marsland of the North Carolina State University at Raleigh.
89
-------
the several States, if latitude is granted them under the law, will view the hydrocarbons problem as
severe in direct relation to their oxidants problem. Further, hydrocarbons are logically categorized
in terms of their reactivity under ultraviolet illumination in the atmosphere, as established by care-
ful (but not always unambiguous) research. According to these findings, methane is not a contrib-
utor; many regulations accordingly, deal in "nonmethane hydrocarbons." Moreover, since the
products of incomplete combustion are chemically quite similar to intermediates in the photochem-
ical reactions leading to oxidants, it is understandable why special attention is paid to flame process-
ing and heat curing. Finally, since exhaust from the internal combustion engine has long been
recognized as a major contributor of hydrocarbons, the. technology of sampling and analyzing hydro-
carbons owes its advanced state to the automobile. We look, in fact, to Federal regulations2 on the
testing of prototype automobiles for guidance.
Precisely because these emissions are ordinarily present in the air at high dilution (less than 1
ppm), there has emerged a marvelously sensitive analytical method: the hydrogen flame ionization
detector (FID). Because a large volume of air is required in this method, it has been found useful
to collect the sample in a large plastic bag. Because hydrocarbons are soluble in such plastics as
polyethylene and Saran, the preferred bags are made of polyvinyl fluoride, an expensive material.
To insure that certain of the heavier hydrocarbons do not condense when the gas sample is cooled
to ambient conditions, metered quantities of dilution air may be required. (Even dilution air is
inadequate to prevent the condensation of portions of a tenter-frame exhaust.) Because methane
is not in this category, these components would, if present, have to be separated and corrected for.
In summary, take a large sample in a special plastic bag, with metered dilution air if need be, measure
TOG by FID, and correct for methane and CO.
As indicated above, tenter-frame exhaust will severely tax the survey team. It is probably best
sampled as particulate matter, using a filter or, better, an impinger, which demonstrably collects it.
In a sense, we are really fortunate that the particle size of this aerosol is nearly uniform—a conse-
quence of the mode of its formation. The collection device is likely to be either a success or a
miserable failure. A high-volume sampler, which might be used to study the ambient atmosphere,
will probably inhale too much dilution air when misused as a stack sampler; it will be entirely un-
suitable for determining the efficiency of a control device. A conventional sampling train should be
used for particulate matter by insertion into the ductwork before the exhaust can cool appreciably.
It will be necessary to wash these with a volatile solvent, so that the oil can be determined by
evaporating it. (Caution: Ether and chloroform are favorites for this step.) It might seem sufficient
to use a simpler bubbler, but this exhaust will at this point be a fine aerosol, not a gas, and the
collection efficiency of most bubblers is inadequate.
Mill management would almost certainly employ a consulting engineer to perform the kind of
sampling and analysis described above, were it not for the obligation of periodic reporting to some
of the States. A reading of the current air-pollution regulations of the several States in Region IV
suggests that mills in North Carolina, Kentucky, and Tennessee should take note.
REFERENCES
1 "Code of Federal Regulations," chapter 40, part 51, as found in the Federal Register: 36 FR
22398 of Nov. 25, 1971; 36 FR 24002 of Dec. 17,1971; 36 FR 25233 of Dec. 30,1971; 37 FR
26310 of Dec. 9,1972; and 38 FR 6279 of Mar. 8, 1973.
2 "Code of Federal Regulations," chapter 40, part 85, as found in the Federal Register: 36 FR
22448 of Nov. 25, 1972; 37 FR 669 of Jan. 15, 1972; 37 FR 18262 of Sept. 8, 1972.
90
-------
Chapter II
PARTICUL^TE CONTROL*
SOURCE, EFFECT, AND ANALYSIS OF THE PARTICULATE EMISSIONS
Polyester and other synthetic cloth may be heated before or after dyeing or printing in dryers
or tenter frames, with air temperatures in the 300°-400° F range, in order to prepare it for a subse-
quent process or to give it certain finished characteristics. At these temperatures, a portion of any
residual spinning and knitting oils, resins, or other high-boiling-point organics in the cloth will be
volatilized and eventually exhausted to the outside air. Before being emitted, or as it mixes with
outside air, the oils or other organics cool enough! to condense as an odorous, bluish-white, sub-
micron smoke. j
Depending on the amount of residual organises in the cloth, this smoke can be in violation of
the visible emission regulation (Ringelmann 1 or 20 percent opacity) by a wide margin, if uncon-
trolled. Based on limited information, it appears jthat as far as residual oils are concerned, a violation
is likely to occur when the cloth contains 0.5 perbent or more by weight. Due to the visible and
odorous nature of this emission, many justifiable 'complaints to the air-pollution-control agency
from people within 1,000 feet or so of the stack have also resulted in citations for violation of
nuisance or odor regulations. Depending on stack height, local topography, and meteorological
conditions, this distance can change significantly.' This smoke by weight is a relatively small emis-
sion and, thus, will not be in violation of a particulate-emission (by weight) regulation, which all
States now have. However, if the State has a hydrocarbon-emission regulation, the smoke plus any
organics still in the gaseous state in the exhausted air could result in a violation, because this type of
regulation is more weight restrictive. i
Before methods of abatement are explored, a determination of the types, state, and amounts
of constituents in the emissions should be made. 'The quickest and cheapest way is a chemical
analysis of the organics in the cloth, both before tod after the high-temperature heating process.
This analysis possibly could be done by a company chemist. The results and a prediction of the
effect on the organics by the heating and subsequent cooling can provide good information about
the emission constituents. The most accurate and complete information is provided by source
sampling done in the exhaust ductwork or stack from the dryer or tenter frame. However, this
requires special equipment and a team of at least jtwo people trained in its use. Source sampling is,
therefore, usually a hired service and costs on thej order of $1,000-$5,000, depending on the number
of stacks sampled and the extent of the analysis df ,the samples taken.
i
EXPECTED EFFECTIVENESS AND RELATIVE COST OF VARIOUS METHODS
OF ABATEMENT
Before considering an emission-control systejm, the possibility of a process change, which
would reduce the amount of residual organics in ijhe cloth, should be explored. The easiest and
cheapest change would be an additional or more effective scouring at some stage of processing prior
to high-temperature heating. The results of bettei: scouring are limited in many cases, but could at
least reduce the required effectiveness of a control system, Dry cleaning can remove the residual
organics so well that unless another high-boiling-p'pint organic is used in a subsequent process, no
*Prepared by Thomas M. Noel of the Rhode Island Department of Health, Providence, R.I.
-------
emission control is needed on the exhaust of an eventual heating process. Unfortunately, a con-
tinuous dry-cleaning system is expensive and has been installed primarily for productive effects
rather than pollution control. However, a mill with a visible-emissions violation should consider it
as a possible alternative to an entirely nonproductive exhaust-control system.
There are three basic approaches to exhaust-emission control that have representative equip-
ment installed in dyeing and finishing mills: incineration, scrubbing, and electrostatic precipitation.
For any control system, a working estimate is that the installation cost will equal the cost of the
control device alone. Incineration is highly effective on any organic emission. Complete oxidation
is obtained if the incinerator is operated at 1,300°-1,500° F, with a residence time of approximately
0.5 second. The only possible drawback to the effectiveness of incineration occurs if a substantial
amount of a chlorinated hydrocarbon is present as hydrochloric acid is a byproduct. Chlorinated
hydrocarbons are sometimes used as dye carriers, but it is not known whether the residual from
the dyeing process is enough to be a problem. The main disadvantage of incineration is a high
operating cost—$2/h/l,000 ft3 /min. The addition of a heat-recovery system can cut this cost in
half, but will double the equipment cost and increase the maintenance cost.
Scrubbers collect the smoke most efficiently if they are a high-energy type, that is, with a
large pressure drop between inlet and outlet. Since the residual oils are only slightly soluble in
water, absorption is not the important collection mechanism. After sufficient cooling to condense
the volatilized oils, impaction between the smoke particles and the scrubbing liquid is potentially
the primary one. For submicron particles, the latter mechanism can be efficient only if there is a
large energy input. For runs of cloth with relatively large amounts of residual oils, it appears that
the scrubber must have a 40-inch (H2O) pressure drop to comply with the 20-percent opacity limit.
Although some low-energy scrubbers (less than 10-inch pressure drop) significantly reduce the smoke,
none will provide compliance under this circumstance. An important disadvantage of the high-energy
scrubber is its relatively high operating cost due to the power requirement. Equipment costs do not
seem to vary much with scrubber type—$2.50/ft3/min is a typical price.
Electrostatic precipitators (ESP) can sufficiently collect submicron smoke to comply with the
opacity limit, if they are operating properly. In this application, the temperature prior to entry into
the ESP must be low enough to condense the volatilized oil to smoke. Any low-boiling-point
organics remaining in the gaseous state in the exhaust will not be collected, and any associated odor
could still be a problem. Fortunately, in many cases, these are not present in significant amounts,
and the disagreeable odor is mostly associated with the oil smoke. To operate properly, the collec-
tion surfaces of the ESP must be kept reasonably clean. For this reason, a prescrubber for solid
particulates, which would otherwise cake on the surfaces, or a system for automatic cleaning must
be added in some applications. The operating cost of an ESP is relatively low, mainly because of
the small amount of electrical energy required (100 W/1,000 ft3/min). The equipment cost may be
somewhat less than a scrubber.
CASE HISTORIES OF RECENTLY INSTALLED CONTROL EQUIPMENT
High-Energy Scrubber
The installation is on a 5,000 ft3 /min exhaust of a tenter frame in Coventry, R.I. It is a
venturi-type scrubber utilizing surfactant and alkaline additives and is operated at a 34-inch H2O
pressure drop. Several similar models of this scrubber have been installed at mills in North Carolina.
The one in Rhode Island was installed in the spring of last year after several years of complaints by
many neighborhood residents to the mill, the town council, and the State air-pollution-control
agency. During the period of complaints, there was an ineffective spray scrubber on the tenter-frame
exhaust. There are a considerable number of homes within a 100-1,000 feet range from the stack.
92
-------
Since the installation, there have been no complaints of smoke or odor to the mill or the air-
pollution-control agency. However, for the first several months after installation, there were com-
plaints of noise due to the 100-horsepower fan on the scrubber, which is located on the roof of the
mill. The scrubber and the motor-fan combination were enclosed in a soundproofed housing at the
time of installation, but it was not until the exhaust stack was also enclosed that the noise was re-
duced enough to bring an end to the complaints. Although there has been, in general, a large reduc-
tion in visible emissions (and odor), opacity limits are not always met. The violation (approximately
50 percent opacity) occurs on runs of cloth known to contain the largest amount of residual oils
(1 percent by weight according to the plant manager). They constitute approximately 10 percent
of the production through the tenter frame. This scrubber-fan system is capable of being operated
at 42 inches H2O. Significant reduction of the smoke from these runs would be expected if it were
so operated.
Low-Energy Scrubber
The installation is on a 10,000 ft3 /min exhaust of a tenter frame in Pawtucket, R.I. It is a
packed-bed, cross-flow, two-stage scrubber, utilizing surfactant and alkaline additives. It is operated
at a 3-inch H2 O pressure drop. Several similar models of this scrubber have been installed on tenter
frames in New Jersey. It was installed this past summer, again, after many complaints from neigh-
borhood residents, the nearest of whom is approximately 300 feet from the stack.
Since the installation, there have still been complaints of smoke and odor. Certain runs of
cloth produce smoke with approximately 50 percent opacity. Although it has not as yet been
determined, it is likely that these runs contain relatively larger amounts of residual oils than the
runs that do not cause a violation. Although this scrubber has reduced the smoke and odor con-
siderably from the uncontrolled situation, it is unlikely that it can be operated with a significant
increase in efficiency. If this proves to be the case, one solution would be to reduce the residual
oils by scouring or dry cleaning.
93
-------
-------
Chapter 11II
SOLVENT PROCESSING AND RECOVERY*
During the past several years, we have seen many and varied changes taking place in the process-
ing of textile products. One of the most dramatic of these has been the increase in popularity of
knitted fabrics. Because of the different requirements in the treatment of the supply yarns for the
knitting machine, as opposed to those of the loom (such as oil-base lubricants rather than cornstarch,
CMC, or PVA sizes), several new processing steps in the field of dyeing and finishing are being added
to those traditionally used to cope with the changing demands.
In the processing of piece-dyed fabrics, oil-base lubricants are applied on the texturizing machine
or winder. The lubricant is normally emulsified and washed from the fabric by an aqueous scouring
procedure at the beginning of the dye cycle. This practice deals with relatively small amounts of
solvents in low concentrations and makes solvent recovery impractical at present.
The processing of fancy or yarn-dyed goods makes the use of solvent-processing equipment
supported by solvent-recovery systems much more attractive and productive. Here, the lubricant
is applied to the yarn during the winding operation following yarn dyeing. After knitting, the lubri-
cant must be removed from the fabric to allow the successful application of various finishes to
provide the desired fabric characteristics. At this point, the manufacturer must choose between the
more conventional aqueous method of emulsifying the lubricant, followed by washing and rinsing,
or solvent removal through the utilization of either batch or continuous dry-cleaning machines.
Many considerations, not the least of which is the growing concern for the elimination of water
pollution and the ever-tightening regulations in this area, encourage the selection of nonaqueous
systems, or those that will minimize water requirements and thereby reduce and simplify the prob-
lems of plant-effluent treatment. The use of solvent versus aqueous systems has demonstrated re-
duction in total plant-water requirements of 20 gallons per pound to 5 gallons per pound. It must
be pointed out that this comparison is based on the performance of different plants rather than
actual reduction in one plant.
Upon making the decision to employ solvent processing in a manufacturing plant, provisions
must also be made for solvent recovery to make the process economical and to provide air-pollution
protection. Solvent-processing equipment and solvent-recovery systems are so intimately related
that the most reasonable approach for the purchase of both systems is to buy an integrated system
for solvent processing and recovery from a single supplier. This gives the plant the distinct advan-
tage of single responsibility for the successful installation and ensuing operation of the equipment.
Upon beginning the installation of solvent-processing and recovery equipment in a manufactur-
ing plant, the plant manager and his staff are faced with somewhat new and different problems, and
many familiar problems have taken on greater importance.
The solvent-processing and recovery equipment must, as nearly as possible, totally contain the
solvent used (normally perchlorethylene) to assure a safe atmosphere for employees and to provide
for maximum solvent recovery to make the process economical. OSHA regulations place limitations
on the amount of perchlorethylene in the plant atmosphere. This requirement states that the concen-
tration of perchlorethylene may not exceed 100 ppm on an 8-hour, time-weighted average, and shall
not exceed 300 ppm for more than 5 minutes during any 3 hours of an 8-hour period. Perchlorethyl-
ene detectors are considered essential to provide data necessary to assure compliance with the
*Prepared by Raymond M. Allen of Deering Milliken Service Corporation, Spartanburg, S.C.
95
_
-------
regulations and serve as a guide for the plant maintenance staff in detecting leaks and malfunctions
of the solvent-handling and recovery equipment. Perchlorethylene detection devices are available
in both permanently mounted and portable models. Additionally, the fixed units have indicating
and recording features, as well as the capability to sound alarms, actuate warning lights, etc. De-
tectors should be mounted at the entry and exit ends of processing machinery, in the area housing
the solvent-recovery equipment, and at any other point that may be susceptible to solvent leaks.
At least one portable unit is recommended to allow monitoring in areas not covered by fixed units
and to assist in detecting and locating solvent leaks.
It has been theorized that excessive perchlorethylene concentrations in the plant atmosphere
may cause additional problems. Assuming that the burners on gas-fired tenters draw in solvent
fumes with the combustion air, convert the fumes to hydrochloric acid gas, and deposit this on the
fabric, it is conceivable that at some point, solvent concentrations in the plant air could cause
browning of the cotton compound of cotton-polyester blends and degradation of dyes resulting in
off-shade goods. It has not been determined exactly what the critical concentration of perchloreth-
ylene may be, but it is generally expected to be in the 200-500 ppm range.
Actual problems experienced by a plant in the installation, startup, and operation of a solvent
dry-cleaning process with solvent recovery are summarized as follows:
• Solvent consumption: Solvent consumption during the startup phase of the equipment can
be expected to run as high as 20-30 percent. After debugging and fine tuning the equipment,
consumption can be expected to decrease to 5-8 percent. Attaining the manufacturer's
claims of 3 percent solvent consumption appears difficult, if not impossible, to attain.
• Solvent leaks: contributing factors
— Machinery vibrations
— Poorly or improperly fitted couplings and flexible hoses and kinks in hoses
— Failure of door seals on machines
— Malfunctions of recovery units
• Squeeze-rool deterioration
96
-------
Chapter IV
SUMMARY*
The presentations on air pollution have pointed out the complexity of an air-pollution-control
and abatement problem, but have also shown that practical measures are available to reduce sub-
stantially the volume and concentration of emission streams. The material discussed has included
the survey, whose purpose is to identify the nature and extent of an emission problem, a review of
the sources of emission problems and discussion of available measures for their control, and, finally,
a discussion of solvent-processing technology, by which some of the inherent problems of air and
water pollution in textile finishing may be avoided.
SURVEY AND ANALYSIS OF EMISSION PROBLEMS
To identify and evaluate the nature of a plant's emission problem generally requires fairly
sophisticated instrumentation and testing methods, beyond the normal capability of plant personnel.
While a general idea of the emission components can be obtained by having samples of the textile
product analyzed before and after each emission-generating operation, a detailed stack analysis,
which can be performed by a number of professional service organizations, will define the nature of
the emission and provide data for selection of proper control devices.
SOURCES
The sources of air-emission problems are relatively few and can be characterized in a number
of ways: unit operations, fiber content, materials used, etc.
In terms of unit operations, texturizing, atmospheric dyeing and finishing, and drying and
curing processes constitute the major sources of emissions, with drying and curing undoubtedly the
largest single source. In terms of fiber content, the greatest problem is associated with polyesters,
primarily due to the volatile carriers required in the disperse dyeing process and the oil-based proc-
essing lubricants that must be applied for efficient handling and fabric formation. Both the carriers
and the lubricants, which are added to the material for proper processing, must be removed later in
finishing. Smoke is produced when textiles coated with lubricating'oils or plasticizer are heated to
300°-400° P in tenter frames, dryers, curers, and ovens. At these temperatures, oils and waxes in
the fiber volatilize and evaporate. Upon cooling to the dew point, condensation takes place, form-
ing an aerosol of submicron oil droplets that appear as the blue-gray smoke. These particles range
from 0.01 to 1 micron (human hair diameter is 100 microns). These particle sizes scatter light per-
fectly, and even a small concentration can produce a highly visible smoke. Typical particulate
codes require stack emissions to be less than 0.02 grain/ft3 (from a 5,000 ft3 /min exhaust, 1 pint
of oil per hour exceeds the requirement). It is possible to have as little as Vz of 1 percent oil content
on the fabric and still exceed air-pollution-code requirements. In addition to being highly visible,
the smoke is also usually odorous.
Other sources include formaldehyde or other resin-finish-related material evolved in the appli-
cation and curing of functional finishes, volatilized spin finish as filament yarns are heated during ,
texturizing, and partial degradation and combustion products from flame-bonded laminating or
*Prepared by G. G. Tewkesbury of the Institute of Textile Technology, Charlottesville, Va.
97
-------
singeing processes. Because of factors such as high temperature or humidity and safety considera-
tions, most sources are usually enclosed or vented, and emission control can be readily applied to
the exhaust stream.
ABATEMENT AND CONTROL MEASURES
Measures to reduce emissions can involve both process changes and emission control. A num-
ber of possible process changes were discussed. Additional scouring and rinsing steps may be used
to remove lubricants and carriers more completely before a fabric is subjected to elevated tempera-
tures, but the benefit of doing so must be weighed against the additional wastewater-treatment
problem generated. Replacement of older atmospheric wet-finishing equipment, with enclosed or
pressurized equipment, should be considered.
Substitution of solvent processing for aqueous processing is a possibility, although presently
limited in scope, particularly in dyeing. Solvent scouring of knit polyester seems to have commer-
cial application, although fully economic operation will depend on attaining higher levels of solvent
recovery. Examples of such solvent-scouring systems are shown schematically in figures IV-1 and
IV-2. An important feature of any solvent system is containment and recovery of solvent evaporated
from the fabric. Without effective recovery, substantial volumes of solvent would be exhausted to
the atmosphere. It is estimated that if the 950 million pounds of knit polyester and nylon finished
last year had been solvent scoured, with a recovery rate of 99 percent, nearly 10 million pounds of
solvent would have been injected into the atmosphere. At present, experience indicates that 95
percent recovery is a more realistic value. More research and development efforts are needed to
make solvent processing more widely applicable. Present systems for collection and recovery of
solvent vapors are based on adsorption and desorption of solvent in activated-carbon beds. A
schematic of this mechanism is shown in figure IV-3.
In addition to process changes, emission controls can be applied to the exhaust streams. An
obvious first step to reduce control costs, however, would be to determine if existing exhaust rates
are necessary. Reduction in total cubic feet per minute should lower the specifications and costs of
any control equipment.
Practical, available technology for treatment of textile air streams seems to center on scrubbers,
which collect particles and dissolve some gaseous products in a water spray; electrostatic precipitators,
which ionize particles and collect them on charged plates; and incineration units, which oxidize
organics at temperatures up to 500° F. While commercial units of all types are available, initial
costs, effectiveness, operating and maintenance costs, and energy requirements vary widely and must
be carefully weighed against the particular stack-emission problem.
It now appears that the textile industry's air-pollution problems, in general, are more amenable
to solution than those of other industries, primarily because the sources of emission are limited to
relatively few processes that can be isolated. When they do occur, however, they generally present
a substantial problem, such as in the dyeing and drying of polyester pile carpets.
In the context of the truism that everything must go somewhere, caution must be observed in
undertaking an air- or water-pollution-control program—solution of one problem does not simply
convert an emission problem into an effluent problem, or the reverse. For example, solution of a
particulate-emission problem by application of a scrubber system to the exhaust stream in turn
creates a potential suspended-solids problem to be handled in processing the wet effluent. Likewise,
use of extra scouring and rinsing steps to remove potentially volatile materials may reduce generation
of fumes at the dryer or tenter frame, but will increase the volume of effluent to be treated. Sub-
stitution of a process-chemical material may alleviate a wash-treatment problem, but may create an
98
-------
DEWAXNG TANK
STEAM FLASH • OFF
WATER WASH TANK
/9
S/yyy^^^yx
'rt/yVYVv1^ -W
wbrRsX>&-
Figure \V-1, Typical machine arrangement for solvent scouring of fabrics.
condensation unit
to the active carbon filter
scouring compartment conveyor drver
Figure IV-2. Fabric-travel diagram of a solvent-scouring range for knit fabrics.
entirely new air-pollution problem when the same chemical is subjected to interaction with other
process chemicals and elevated temperatures in drying and curing.
As with water pollution, the cost of meeting air-quality standards becomes part of the cost of
doing business. It is a task, however, that cannot necessarily be done by the least expensive measure
or piece of equipment. As our ecology reflects the delicate balance and interaction among many
dynamic biological systems, an efficiently operated, environmentally responsive organization reflects
a critical balance and interaction among many dynamic physical, chemical, and economic systems.
Application of effective abatement programs cannot be done by purchase of hardware alone, but re-
quires careful deliberation and planning to insure that the necessary balance of all factors—product
quality, economics, environmental effects, etc.—be maintained.
99
-------
n
Carbon bed
adsorbs solvent
u'. Plant air with
solvent vapor
Adsorption cycle
•4
\
Jj
T
Y
t
v^
V
k
/
Exhaust
^- _,
Separator removes
wastewater, leaves
solvent
I
Steam
Steam removes
solvent from
carbon bed
Desorption cycle *€I
Figure IV-3. Diagrammatic sketch of collection and recovery of solvent vapors using an activated-carbon bed.
100
-------
Appendix A
TABLES OF ADDITIONAL DATA AND INFORMATION
CHARACTERIZING TEXTILE PROCESS
WASTES AND CONSTITUENTS
-------
-------
Table A-1 .-Pollution effects of cotton-processing wastes
Item
Slashing, sizing yarn
Desizing
Kiering
Scouring
Bleaching (range)
Mercerizing
Dyeing:
Aniline black
Basic
Developed colors
Direct
Naphthol
Sulfur
Vats
Wastes, ppm
. PH
7.0-9.5
10-13
8.5-9.6
5.5-9.5
6.0-7.5
5-10
6.5-7.6
5-10
8-10
5-10
BOD
620-2,500
1,700-5,200
680-2,900
50-110
90-1 ,700
45-65
40-55
100-200
75-200
220-600
15-675
11-1,800
125-1,500
Total solids
8,500-22,600
16,000-32,000
7,600-17,400
2,300-14,400
600-1,900
600-1,200
500-800
2,900-8,200
2,200-14,000
4,500-10,700
4,200-14,100
1 ,700-7,400
Table A-2.—Pollution loads of woof wet processes
Process
'Scouring
Dyeing
Washing
Neutralization
Bleaching
pH
9.0-10.4
4.8-8.0
7.3-10.3
1.0-9.0
6.0
BOD, ppm
30,000-40,000
380-2,200
4,000-11,455
28
390
Total solids.
ppm
1,129-64,448
3,855-8,315
4,830-19,267
1,241-4,830
908
Source: J. J. Porter et al., "Water Uses and Wastes in the Textile Industry," Environ.*Sci. Tech.,6C\): 36-41, 1972.
103
-------
Table A-3.-Pollution load of synthetic wet fiber processes
Process
Scour
Scour and dye
Dye
Salt bath
Final scour
Fiber
Nylon
Acrylic/modacrylic
Polyester
Rayon
Acetate
Nylon
Acryl ic/modacry 1 ic
Polyester
Rayon
Acrylic/modacrylic
Polyester
PH
10.4
9.7
8.5
9.3
8.4
1.5-3.7
6.8
7.1
BOD, ppm
1,360
2,190
500-800
2,832
2,000
368
175-2,000
480-27,000
58
668
650
Total solids,
ppm
1,882
1,974
3,334
1,778
641
833-1 ,968
4,890
1,191
Source: J. J. Porter, "Water Uses and Wastes in the Textile Industry," Environ. Sci. Tech., ff(1): 36-41,1972.
104
-------
Table A-4.-Simplified survey-cotton mills, 1958
[78,000 gallons and 96 pounds BOD per 1,000 pounds of cloth]
Item
Grey goods contribution:
Starch (desize)
Natural impurities (kier)
Subtotal
Process chemicals with BOD:
Soap
Acetic acid
Sodium hydrosulfite
Urea
Rhozyme LA
Tergitol NPX
Detergent MPX
Subtotal
Process chemicals without BOD:
Caustic soda (100 percent)
Sodium bicarbonate
Sodium hypochlorite
Sodium chloride
Sulfuric acid
Sodium silicate
Sodium carbonate
Phosphoric acid
Hydrogen peroxide (30 percent)
Sodium chlorite
Subtotal
Grand total
Solids, mg/l
176
81
257
3.3
13.1
27.2
20.5 :
10.9
15.1
2.8
91.9
514 ;
63
57
35
32
16
14
11
7 ;
6
755
1,104
BOD, mg/l
104
31
135
4.6
4.2
1.5
1.8
0.2
0.3
<0.1
12.6
0
0
0
0
0
0
0
0
0
0
0
148
Percent of
total BOD
70
21
91
3.1
2.8
1.0
1.2
0.1
0.2
<0.1
9
0
0
0
0
0
0
0
0
0
0
0
100
Source: J. W. Massilli, N. W. Massilli, and M. G. Burford, "Factors Affecting Textile Waste Treatability," Textile Indust,,
135: 84,1971.
105
-------
Table A-5.-Simplified survey—cotton-synthetic mill, 1969
[25,000 gallons and 47 pounds BOD per 1,000 pounds cloth]
Item
Grey goods contribution:
Synthetic sizing
Starch (desize)
Natural impurities (kier)
Subtotal
Process chemicals with BOD:
Acetic acid
LAS detergent
Print paste solvent
EDTA
Sodium hydrosulf ite
Rhozyme
ABS detergent
Subtotal
Process chemicals without BOD:
Sodium chloride
Hydrogen peroxide (30 percent)
Sodium hydroxide
Hydrochloric acid
Sodium carbonate
Zinc su If ate
Sodium tripoly phosphate
Sodium silicate
Magnesium chloride
Sodium sulfate
Sodium nitrite
Potassium permanganate
Subtotal
Grand total
Solids, mg/l
40
200
neg.
240
26
7
100
29
38
88
7
288
752
68
25
24
21
20
18
12
8
5
5
2
960
1,488
BOD, mg/l
20
140
0
160
14
11
24
8
8
2
<1
67
0
0
0
0
0
0
0
0
0
0
0
0
0
227
Percent of
total BOD
9
62
—
71
6
5
11
3
3
1
29
0
0
0
0
0
0
0
, 0
0
0
0
0
0
100
Source: J. W. Masselli, N. W. Masselli, and M. G. Burford, "Factors Affecting Textile Waste Treatability," Textile Indust.,
135:84,1971.
106
-------
Table A-6.-Simplified survey- viscose rayon velvet mill, 1968
[30,000 gallons and 38 pounds BOD per 1,000 pounds velvet]
Item
Grey goods contribution:
Antistat lubricant
Gelatin size
Subtotal
Process chemicals with BOD:
Detergent
Lubricant— penetrant
Resin finish (waste)
Acetic acid
Subtotal
Process chemicals without BOD:
Sodium chloride
Sodium sulfate
Sodium phosphate
Sodium hydrosulfite
Hydrogen peroxide (35 percent)
Subtotal
Grand total
Solids, mg/l
16
60
76
53
34
150
19 :
256
588 ,
108
36
24
12
768
1,100
BOD, mg/l
12
40
52
46
12
28
12
98
0
0
0
0
0
0
150
Percent of
total BOD
8
27
35
31
8
19
8
65
0
0
0
0
0
0
100
Source: J. W. Masselli, N. W. Masselli, and M. G. Burford, "Factors Affecting Textile Waste Treatability," Textile Indust.,
135: 84, 1971.
107
-------
Table A-7.—Simplified survey—woolen mill, 1953
[60,000 gallons and 425 pounds BOD per 1,000 pounds finished wool]
Item
Grease wool contribution:
Grease, suint, dirt
Subtotal
Process chemicals with BOD:
Soap
Acetic acid
Pine oil
Carding oil
Spinning oil
Detergents
Subtotal
Chemicals without BOD:
Soda ash
Sodium phosphate
Sulfuric acid
Chrome mordant
Sodium sulfate
Subtotal
Grand total
Solids, mg/l
3,000
3,000
152
24
10
10
8
90
294
340
10
4
20
8
382
3,676
BOD, mg/l
500
500
236
15
11
2
1
60
325
0
0
0
0
0
0
825
Percent of
total BOD
61
61
28
2
1
1
<1
<1
39
0
0
0
0
0
0
100
Source: J. W. Masselli, N. W. Masselli, and M. G. Burford, "Factors Affecting Textile Waste Treatability," Textile Indust.,
135:84,1971.
108
-------
Table A-8.—Wool-scouring and wool-finishing wastes
Wool-scouring wastes (250 pounds BOD per 1,000 pounds cloth)
Item
Approximate analysis1
Chemical add-ons:
20-25 percent grease
7-10 percent suint
50 percent sand
1 percent Na2CO3
pH 10-12
15,000 mg/l BOD
36,000 mg/l TS2
12,000 mg/l sand
Wool-finishing wastes (200 pounds BOD per 1,000 pounds cloth)
Wash after fulling:
2-8 percent carding oil
5-10 percent soap
1 percent Na2 CO3
0.5 percent penetrant
Wash after carbonizing:
5-6 percent H2SO4
1-2 percent Na2CO3
Aluminum chloride
Stock dyeing:
5 percent acetic acid
3 percent chromate
2 percent penetrant
2 percent fatty acid leveler
Alternate:
10 percent NH4 sulfate
pH 10-12
9,000 mg/l BOD
18,000 mg/l TS
pH4.0
100 mg/l BOD
4,000 mg/l TS
3,000 mg/l sulfate
pH7.0
3,000 mg/l BOD
3,000 mg/l sodium acetate
7,000 mg/l TS
50-250 mg/l chromium
pH7.0
450 mg/l BOD
6,000 mg/l NH4 sulfate
Combined finishing waste
pH 10-11
4,000 mg/l BOD
9,700 mg/l TS
1,000 mg/l sulfate
15-90 mg/l chromium
1 It is assumed that 2,000 gallons of water is used for each 1,000 pounds of cloth in
each process.
JTS indicates total solids.
Note.—Masselli suggested (May 1973 AATCC Symposium, Washington, D.C.) that tables
A-8, A-9, A-10, and A-11 be inspected also to obtain an idea of the nature of various wastes.
109
-------
Table A-9.—Cotton finishing
[100-200 pounds BOD per 1,000 pounds cloth]
Item
Approximate analysis1
Chemical add-ons:
Desize
10 percent starch
0.5 percent enzyne
Alternate:
5 percent PVA
Caustic scour:
4-8 NaOH
1 percent waxes, pectins
0.5 penetrant
Combined desize/scour
Bleaching:
2 percent H2Oj
2 percent Na silicate
0.3 percent NaOH
Mercerizing:
2-6 percent NaOH
Dyeing:
2-4 percent dyes
1-3 percent leveling
1-3 percent emulsifying
1-3 percent softening
0.5 percent chelating
0.5-30 percent NaCI
Printing-waste pastes
Printing-wash after printing
1 percent detergent
PVA adhesive
Combined equalized effluent
pH6.8
3,000 mg/l BOD
6,000 mg/l TS2
4,300 mg/l carbohydrates
pH 7.0
300 mg/l BOD
7,000 mg/l TS
6,000 mg/l PVA
pH 13.0
1,800 mg/l BOD
8,000 mg/l TS
3,600 mg/l NaOH
pH 10-13
4,800 mg/l BOD
14,000 mg/l TS
3,600 mg/l NaOH
4,300 mg/l carbohydrates
pH 9-11
600 mg/l BOD
1,200 mg/l H2O2
1,000 rng/l Na silicate
240 mg/l NaOH
pH 11-14
780 mg/l BOD
8,000-18,000 mg/l TS
3,000-6,000 mg/l NaOH
pH 4.5-8.0
200-30,000 mg/l BOD
500-40,000 mg/l TS
100-30,000 mg/l NaCI
400-1,000 X dilution to reduce color
pH 4.0-8.0
50,000-400,000 mg/l BOD
500,000 mg/l solvent
500,000 mg/l TS
30,000-600,000 X dilution to reduce color
pH 4.5-8.0
600-1,800 mg/l BOD
1,200-3,600 mg/l TS
pH 11-13
1,200-2,400 mg/l BOD
4,000-12,000 mg/l TS
500-1,500 mg/l NaOH
1,000-4,000 mg/l NaCI
500-3,000 mg/l TOC
1,500-4,500 mg/l COD
1 It is assumed that 2,000 gallons of water is used for each 1,000 pounds of cloth in each
process.
2TS indicates total solids.
110
-------
Table A-10.—Polyester knits
[30-60 pounds BOD per 1,000 pounds cloth]
Item
Approximate analysis1
Chemical add-ons:
Scouring waste:
3-10 percent coning-knitting oils
0.5 percent detergent
Dye waste:
2-3 percent acetic acid
3-6 percent perchloroethylene
1 percent naphthalene sulfonic acid
4 percent lubricant
1 percent defoamer
0.5 percent EDTA
Alternate carriers:
3 percent trichlorobenzene
3-4 percent butylbenzoate
4-10 percent biphenyI
Combined equalized effluent
pH7.0
1,200mg/l BOD
4,000 mg/l TS2
3,000 mg/l oils
pH 3.8-4.6
1,000 mg/l BOD
1,000 mg/l acidity
2,200 mg/l perchloroethylene
1,000 mg/l acetate
pH 4.5-5.2
1,100 mg/l BOD
3,100 mg/l TS
1,500 mg/l oils
900 mg/l perch lorethylene
500 mg/l acetate
Table A-11 .-Other synthetics-rayon, acetate, nylon, Dacron, Orion
[40-100 pounds BOD per 1,000 pounds cloth]
Item
Chemical add-ons
Approximate analysis1
pH 7.0
300-1 ,800 mg/l BOD
2,000-1 0,000 mg/l TS2
1 It is assumed that 2,000 gallons of water is used for each 1,000 pounds of
cloth in each process.
2TS indicates total solids.
Ill
-------
Table A-12.—Field analysis of rug-dyeing and associated wastes
Process
Tap water
Rug beck, chemical
added with no color
dye
Rug beck liquor, be-
gin of dye cycle
Rug beck liquor, near
middle of dye cycle
Rug beck liquor, end
of dye cycle
Rug beck rinse
Boiler make-up
Boiler blowdown
Zeolite backwash
Basin effluent
Clarifier effluent
Basin effluent3
Color
Clear, colorless
Cloudy, murky
gray, with
yellowish tint
Deep green
Deep olive
green
Brown green
Clear, colorless
Clear, colorless
Murky, light
gray, white
floatables
Clear, colorless
Murky, yellow
colloidal
matter
Fairly clear.
with brown
solids
Varies with
color of dye
Odor
None
Slight
None
None
Slight
"med-
ical"
odor
None
None
None
None
None
Slightly
musty
Varies
from
none
to
slight
Tur-
bidity
(mg/l
as
silica)
<10
180 2
500
>840
>840
>840
33
14.0
400
12.3
600
300
174
PH1
8.10 at 74° F
7.70
8.85 at 80° F
8.70
9.1 Oat 83° F
8.80
8.85 at 115° F
8.60
8.20 at 11 5° F
8.10
6.60 at 78° F
7.15
8.50 at 110° F
7.65
11.25 at 126° F
11.50
8.60 at 72° F
8.60
8.40 at 85° F
8.10
8.25 at 80° F
7.65
7.1 4 at 70° F
Conduc-
tivity
at 25° C,
juratios
/cm
630
6,400
7,375
9,000
8,750
700
635
8,250
930
1,210
925
1,748
Estimated
TDS,
mg/l
409.5
4,160.0
4,793.8
5,850.0
5,687.5
455.0
412.8
5,362.5
604.5
786.5
601.3
1,136.0
Floatable
solids,
percent
0
0
0
0
0
0
Trace
Trace
0
0
Trace
Trace
to
none
Settle-
able
solids,
percent
0
0
0
0
0
<0.1
0
<0.1
0
<0.1
<0.1
0.24
1 First recorded pH value was determined within 1 hour of sampling. Second recorded value determined on 2-17-66 when all
samples were at 68° F.
'First recorded turbidity value taken on 2-16^66. Second value taken on 2-17-66. Large difference indicates some chemical
reaction occurred.
'Average characteristics of six samples taken from 9:30 a.m. to 4:30 p.m. on 3-24-66.
Source: Ralph Stone, "Carpet Mill Industrial Waste System," J. Water Poll. Con. Fed., 44(3): 474,1972.
112
-------
Appendix B
TABLES ILLUSTRATING RELATIVE AMOUNTS USED AND BOD
LOADINGS OF CHEMICALS CONSUMED IN COTTON
FINISHING AND COMPARISON OF VIEWS ON
ACCEPTABLE CRITERIA FOR TEXTILE PROCESS
WATER
-------
-------
Table &-\.—Cotton-finishing process chemicals, consumption and BOD
Chemical
B-2 gum
Wheat starch
Pearl cornstarch
Brytex gum No. 745
KD gum
Slashing starch
Total
Carboxymethyl cellulose
Hydroxyethyl cellulose
Tallow soap
Nacconal IMR
Ultrawet 35 KX
Acetic acid, 80 percent
Mixture of 18 dyes
Cream softener, 25 percent
Formaldehyde-bisulfite condensate
Glycerin
Sodium hydrosulfite
Urea
Finish total solids
Kierpine extra
Merpol B
Glucose
Gelatin
Caustic, 76 percent
Soda ash
Ammonia
Potassium carbonate
Trisodium phosphate
Sodium perborate
Sodium silicate
Liquid soda bleach
Hydrogen peroxide
Sodium chloride
Sodium dichromate
Sulfuric acid
Hydrochloric acid
Amount used,
lb/1,000
Ib goods
22
;16
14
4
4
2 96
150
,
' —
20-100
1
.—
27
37
20
14
3
11
13
8
, 5
4
—
—
118
42
7
3
2
3
6
4
5
7
6
10
6
BOD, percent1
61
55
50
61
57
—
—
3
3
3 55
4
0
52
7
39
27
64
22
9
39
61
44
71
91
(4)
(4)
(4)
(4)
(4)
(4)
(4)
(4)
(4)
(4)
(4)
(4)
(4)
BOD,
lb/1,000
Ib goods
13.4
8.8
7.0
2.4
2.3
53.0
82.9
_
—
11-55
0.04
0
14.0
2.6
7.8
3.8
1.9
2.4
1.2
3.1
3.1
1.8
—
_
(4)
(4)
(4)
(4)
(4)
(4)
(4)
(4)
(4)
(4)
(4)
(4)
(4)
1 Based on weight of chemical; for example, 1 pound of B-2 gum (61 percent BOD) would require
0.61 pound of oxygen for stabilization. '
'Calculated from analytical survey. :
3 Apparently contained high water content; dry soaps averaged 130 to 150 percent BOD.
"Negligible BOD assumed.
Source: J. W. Masselli, N. W. Masselli, and M. G. Burford, "A Simplification of Textile Waste
Survey and Treatment," New England Interstate Water Pollution Control Commission, Boston, Mass.,
1959.
115
-------
Table B-2.—Analysis of a sample of acceptable process water
Particulars of the impurities
Total dissolved solids
Suspended matter
Total alkali
Total hardness
Ferrous salts
Manganese salts
Silica
Aluminum salts
Other heavy metals
Color (platinum units)
PH
Quantity of the impurity
present, ppm
TDS
turbidity
CaCO3
CaCO3
Fe203
MnO2
SiO2
AI203
R203
200.00
1.50
100.00
15.00
0.05
0.05
10.00
0.40
0.10
5.00
7.5-8.0
Source: Colourage, Apr. 20, 1972.
Table B-3.—Upper permissible limits for dyeing source: Three different sources
Item
Color, ppm
Total hardness as CaCO3, ppm
Alkali to MeO as CaCO3 , ppm
Fe, ppm
Mn, ppm
Total dissolved solids, ppm
Suspended solids, ppm
PH
Chloride, ppm
Sulfate, ppm
Silica asSi02, ppm
Aluminum, ppm
1
2-5
10-25
35-65
0.03-0.10
0.02-0.10
65-150
Nil
7.0-7.5
0-30
0-30
Nil
Nil
2
5-20
15-30
150
Nil
0.05
100-200
5
6.5-7.5
Low as possible
80-100
0.5-120
0-0.25
3
5
10-30
75-100
0.01-0.02
0.01
200
Nil
7.0
20-40
—
—
0.30-0.40
Source: Textile J. Australia, Nov. 1970.
116
-------
Table B-4.—Average "limits" of concentration of impurities
for many textile-processing operations
Item
Turbidity, ppm as silica
Color, ppm platinum scale
Total hardness, ppm as CaCO3
Iron, ppm as Fe
Manganese, ppm as Mn • • '
Alkalinity to methyl orange, ppm as CaCOa
Total dissolved solids
ppm
0.5-3
2-5
0-25
0.02-0.1
0.02
35-64
65-150
Source: Tex. Chems. and Aux., V. J.Calise (Graver).
Table B-5.—Tolerable limits of various substances in the
textile industries
Item
Total hardness
S04
Cl1
N03
P04
TDS
Free CI2
Fe
Mn
Cu3
Al
Cotton, silk, and man-
made fibers, mg/l
70
250
250
0.5
(2)
500
6.1
0.3
0.05
0.01
0.25
Wool, mg/l
100
250
250
0.5
(2)
500
0.1
0
0
0
0.25
*SO4 and Cl must not vary; this is more important than absolute value.
2 No limit within reason.
3 Any heavy metals as Cu.
Source: J. Soc. Dyers Colorists, 481, Dec. 1971.
117
-------
Table B-6.—General textile-processing water-quality specifications
Item
Turbidity, mg/l as Si02
Color
Hardness, mg/l as CaCO3
Iron, mg/l as Fe
Manganese, mg/l as Mn
Total dissolved solids, mg/l
Aluminum, mg/l as Al
Heavy metals, mg/l
Silica, mg/l as SiOj
Alkalinity, mg/l as CaCO3
Cotton
0-25
0-50
0-50
0-0.2
0-0.1
200
0.01
10
75-100
Rayon
1.0
5.0
10.0
0.05
0.02
200.0
0.25
0.01
10.0
75.0
Source: T. A. Alspaugh, Proceedings 13th SMIWC, 1964.
Table B-7'.—Analysis of fresh water typically used by finishing plants
Item
BODS
COD
Total solids
Dissolved solids
Suspended solids
Volatile solids
PH
Alkalinity
Hardness
Phosphorus
Total nitrogen
Nitrate
Chloride
Plant A
0
5
50
45
2
g
7.5
18
3
0.1
0.6
0.3
—
Plant B
0
2
92
88
4
20
7.6
36
8
—
-
—
0.6
Plant C
0
6
60
58
2
5
7.8
10
12
—
—
—
—
Note.—All results are reported in ppm except pH and were performed according to "Stand-
ard Methods for the Examination of Water and Wastewater" (13th Edition).
Source: J. J. Porter, Am. Digest Rep., 79, Apr. 1973.
118
-------
-------
-------
METRIC CONVERSION TABLES
Recommended Units
Description
Length
Area
Volume
Mass
Time
Force
Moment or
torque
Stress
Unit
metre
kilometre
millimetre
micrometre
square metre
square kilometre
square millimetre
hectare
cubic metre
litre
kilogram
gram
milligram
tonne or
megagram
second
day
year
newton
newton metre
pascal
kilopascal
Symbol
m
km
mm
fan.
m2
km2
mm2
ha
m3
1
kg
g
mg
t •
Mg
s
d
year
N
N-m
Pa
kPa
Comments
Basic SI unit
The hectare (10 000
m2) is a recognized
multiple unit and
will remain in inter-
national use.
The litre is now
recognized as the
special name for
the cubic decimetre.
Basic SI unit
1 tonne = 1 000 kg
1 Mg = 1 000 kg
Basic SI unit
Neither the day nor
the year is an SI unit
but both are impor-
tant.
The newton is that
force that produces
an acceleration of
1 m/s2 in a mass
of 1 kg.
The metre is
measured perpendicu-
lar to the line of
action of the force
N. Not a joule.
Customary
Equivalents
39.37 in.=3.28 ft=
1.09yd
0.62 mi
0.03937 in.
3.937 X 10'3=103A
1 0.764 sq ft
= 1.196sqyd
6.384 sq mi =
247 acres
0.00155 sq in.
2.471 acres
35.314 cu ft =
1.3079cuyd
1. 057 qt = 0.264 gal
= 0.81 XlO^acre-
ft
2.205 Ib
0.035 oz = 1 5.43 gr
0.01543 gr
0.984 ton (long) =
1.1 023 ton (short)
0.22481 Ib (weight)
= 7.233 poundals
0.7375 ft-lbf
0.02089 Ibf/sq ft
0.14465 Ibf/sq in ;
Description
Velocity
linear
angular
Flow (volumetric)
Viscosity
• Pressure
Temperature
Work, energy.
quantity of heat
Power
Application of Units
Description
Precipitation,
run-off.
evaporation
River flow
Flow in pipes,
conduits, chan-
nels, over weirs.
pumping
Discharges or
abstractions.
yields
Usage of water
Density
Unit
millimetre
cubic metre
per second
cubic metre per
second
litre per second
cubic metre
per day
cubic metre
per year
litre per person
per day
kilogram per
cubic metre
Symbol
mm
m3/s
m3/s
l/s
m3/d
m3/year
I/person
day
kg/m3
Comments
For meteorological
purposes it may be
convenient to meas-
ure precipitation in
terms of mass/unit
area (kg/m3).
1 mm of rain =
1 kg/m2
Commonly called
the cumec
1 l/s = 86.4 m3/d
The density of
water under stand-
ard conditions is
1 000 kg/m3 or
1 000 g/l or
1 g/ml.
Customary
Equivalents
35.314 cfs
15.85gpm :
1.83X10-3gpm
0.264 gcpd
0.0624 Ib/cu ft '•
1
Description
Concentration
BOD loading
Hydraulic load
per unit area;
e.g. filtration
rates
Hydraulic load
per unit volume;
e.g., biological
filters, lagoons
Air supply
Pipes
diameter
length
Optical units
Recommended Units
Unit
metre per
second
millimetre
per second
kilometres
per second
radians per
second
cubic metre
per second
litre per second
pascal second
newton per
square metre
or pascal
kilometre per
square metre
or kilopascal
bar
Kelvin
degree Celsius
joule
kilojoule
watt
kilowatt
joule per second
Symbol
m/s
mm/s
km/s
rad/s
m3/s
l/s
Pa-s
N/m2
Pa
kN/m2
kPa
bar
K
C
J
kJ
W
kW
J/s
Comments
Commonly called
the cumec
Basic SI unit
The Kelvin and
Celsius degrees
are identical.
The use of the
Celsius scale is
recommended as
it is the former
centigrade scale.
1 joule = 1 N-m
where metres are
measured along
the line of
action of
force N.
1 watt = 1 J/s
Customary
Equivalents
3.28 fps
0.00328 fps
2.230 mph
1 5,850 gpm
= 2.120cfm
15.85 gpm
0.00672
poundals/sq ft
0.000145 Ib/sq in
0.145 Ib/sq in.
14.5 b/sq in.
5F
¥ ~17-77
2.778 X10'7
kwhr =
3.725 X ID'7
hp-hr = 0.73756
ft-lb = 9.48 X
10'4 Btu
2.778 kw-hr
Application of Units
Unit
milligram per
litre
kilogram per
cubic metre
per day
cubic metre
per square metre
per day
cubic metre
per cubic metre
per day
cubic metre or
litre of free air
per second
millimetre
metre
lumen per
square metre
Symbol
mg/t
kg/m3d
m3/m2d
m3/m3d
m3/s
l/s
mm
m
lumen/m2
Comments
If this is con-
verted to a
velocity, it
should be ex-
pressed in mm/s
(1 mm/s = 86.4
m3/m2 day).
Customary
Equivalents
1 ppm
0.0624 Ib/cu-ft
day
3.28 cu ft/sq ft
0.03937 in;
39.37 in. =
3.28 ft
0.092ft
candle/sq ft
-------
U.S. ENVIRONMENTAL PROTECTION AGENCY • TECHNOLOGY TRANSFER
------- |