TEXTILE WASTE TREATMENT:
COLOR REMOVAL AND SOLIDS HANDLING CHARACTERISTICS
Richard W. Statu, Graduate Student
Charles P. Boepple, Graduate Student
William R. Knocke, Assistant Professor
Department of Civil Engineering
Virginia Polytechnic Institute and State University
Blacksburg, Virginia 24061
INTRODUCTION
The textile industry produces a variety of waste streams that vary widely with respect
to parameters such as grease, biochemical oxygen demand, chemical oxygen demand, heavy
metals, surfactant content, suspended solids and color. As discharge and pretreatment standards have become increasingly more stringent, the industry has responded by upgrading
their treatment systems. Traditionally, the emphasis of treatment has been aimed at reducing
the oxygen demand and solids level of the waste prior to discharge. Wastes that exhibit
high levels of one or both of these parameters have vivid and often extreme effects upon the
receiving stream.
In recent years, textile waste discharges have been scrutinized for an additional parameter, namely color. Color has been viewed by many as an esthetic parameter that would
have little impact on the biota of a receiving stream or a sewage treatment plant. However,
concern has been expressed about the possible toxic or inhibitory effects that textile dyes
may have on aquatic systems. A research study undertaken by the American Dye Manufacturer's Institute, Inc. [ 1 ] included an assessment of the effects of dyes on fish, aerobic and
anaerobic systems, and algae. The dyes chosen for study were deemed to be representative
of those used by the textile industry. The results showed that varying degrees of toxicity
and/or process upset were noted with a significant number of the dyes investigated. Thus,
it is apparent that dyes must be considered more than an esthetic problem.
In light of the above considerations and others, the United States Environmental Protection Agency (EPA) proposed effluent limitations and pretreatment standards for the
textile industry, including regulations related to effluent color levels [21. Table I presents
the proposed color standards currently scheduled for implementation in 1983. These effluent color limitations are extremely stringent and will require extensive treatment of most
waste streams to reach such low residual color levels.
Table I. Proposed EPA Effluent Color Standards for the Various Subcategories of the Textile Industry
(Maximum Average 30-day Values for Color)3
Effluent Color Level for
Effluent Color Level for
Textile Subcategory
Existing Plants
New Plants
Wool Scouring
1500
1500
Wool Finishing
120
120
Woven Fabric Finishing
220
120
Knit Fabric Finishing
220
120
Carpet Finishing
220
120
Stock and Yarn Finishing
220
120
Nonwoven Manufacturing
220
120
Felted Fabric Processing
240
120
aAll effluent color levels expressed in ADMI color units.
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