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  • POLLUTION PREVENTION STUDIES IN THE TEXTILE WET PROCESSING INDUSTRY

    Submitted by: Ms. Ilse Hendrickx, Graduate Research Assistant

    and Gregory D. Boardman, Associate Professor

    Department of Civil Engineering VPI&SU

    Blacksburg, Virginia 24061

    Submitted to:

    Department of Environmental Quality Office of Pollution Prevention

    629 E. Main Street Richmond, Virginia 23240

    May 1995

  • POLLUTION PREVENTION STUDIES IN THE TEXTILE WET PROCESSING INDUSTRY

    Ilse Hendrickx and Gregory Boardman Department of Civil Engineering

    VPI&SU Blacksburg, Virginia 24061

    ABSTRACT

    The objective of this study was to investigate pollution prevention (P2) opportunities in the textile wet processing industry. This industry uses vast amounts of water, energy and chemicals. P2 audits were conducted at four textile companies. The companies were located in Virginia and included: a denim and soft wash laundry; a fiberglass yarn processing plant; a cotton fabric dyeing and printing plant; and a nylon yarn dyeing and finishing plant.

    Each company was visited several times. Information about the operations, consumption of water, energy and chemicals were obtained by interviewing personnel. Information about wastewater characteristics, permit applications, water treatment and disposal records were obtained from the plant’s records. Wastewater samples from several operations were analyzed for COD, DOC, color, TSS, pH and temperature. Lead, copper, zinc and chromium concentrations were also determined.

    The collected information was used to make recommendations to the management of each plant concerning possible implementations. Reusing non-contact cooling water at the fiberglass processing plant will reduce the water consumption by 76% and results in a savings of $99,400 per year, if an additional chilling unit is not needed. There were several possibilities to reduce the consumption of water, energy and chemicals at the cotton dyeing and printing mill. Implementing counter-current flow between bleach washers will save $ 154,000 per year due to reduced consumption of water and energy. The savings will be $ 336,000 per year if the existing washers are replaced by more efficient washers. Improving the wash schedules and communication with clients at the laundry will reduce the consumption of water and chemicals. Dyebath reuse and counter- current flow of rinse waters were recommended for the nylon yam dyeing and finishing m i l l .

  • ACKNOWLEDGEMENTS

    The authors would like to acknowledge the financial support and guidance provided by the Office of Pollution Prevention of the Virginia Department of Environmental Quality (DEQ) for this study. We would also very much like to thank the kind and considerate personnel of the textile companies that participated in this study.

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  • CHAPTER 1: INTRODUCTION

    Dyes and auxiliary chemicals used in textile mills are developed to be resistant to

    environmental influences. As a result, they are hard to remove from wastewater

    generated during the dyeing processes. The best way to reduce the impact of these dyes

    and chemicals on the environment is by reducing the amount released for treatment.

    Furthermore, conventional waste treatment often causes only a transfer of waste from one

    phase to another. Treatment usually results in the generation of solids, sometimes

    hazardous, which are buried in a landfill. Disposal of waste in a landfill can result in

    groundwater contamination, gas formation and problems with odors. In other words,

    waste treatment is not necessarily a cure. As regulations’ become more stringent,

    companies are forced toward more technologically sophisticated treatment methods. This

    results in an increased cost for waste management and sometimes forces companies to go

    out of business. More and more companies realize that reducing the waste at the source

    is necessary to reduce the cost of treatment.

    In 1990, Congress passed the Pollution Prevention Act. This act reaffirms the

    federal objective of the Emergency Planning and Community Right-To-Know Act (Title

    III of SARA of 1986).

    Pollution prevention (P2) is defined as those measures that eliminate or reduce

    pollution prior to off-site recycling or treatment. Pollution prevention does not only

    reduce water pollution, but also minimizes the release of pollutants to land and air. In

    the Pollution Prevention Act, the Congress defines a multimedia waste management

    hierarchy. Source reduction stands at the top of the waste management hierarchy and is

    followed by reuse and on-site recycling. Off-site recycling is not considered a pollution

    prevention measure. Treatment and safe disposal are listed at the bottom of the hierarchy

    (Smith, 1989a).

    Reducing the volume of waste released through P2 can be accomplished by

    conservation and more efficient use of resources. Source reduction can be achieved by

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  • the following techniques: optimization/conservation of chemicals, chemical substitution,

    process modification, equipment modification and improved maintenance and

    housekeeping.

    The objective of this research was to investigate pollution prevention opportunities

    in the textile wet processing industry. This was achieved through an extensive literature

    review and P2 audits performed at textile companies. In the literature review, the

    different textile wet processing operations are briefly discussed, and a description of

    various source reduction techniques is provided. Many articles were found that provide

    examples of source reduction measures successfully implemented at textile mills. These

    articles were used to clarify the concepts and benefits associated with P2.

    In the second part of the study, P2 audits were conducted at four textile mills.

    The companies included in this study cover a wide range of plants in the textile wet

    processing industry. The mills are all located in Virginia and include:

    1.

    2.

    3.

    A stone and soft washing laundry. This laundry washes denim products,

    cotton apparel and hats.

    A large fiberglass processing plant. The mill receives fiberglass yarn,

    weaves it into a woven fabric, and applies special finishes.

    A large cotton printing, dyeing and finishing facility. Pure cotton and

    polyester/cotton blend fabric are received from weaving mills all over

    the world.

    4. A nylon yarn dyeing and finishing facility. The processed yarn is used for

    the production of industrial carpets.

    Each plant was visited several times over the course of the P2 audit. The study

    was conducted by touring the production facility of the plant, interviewing employees,

    observing daily operations and reviewing existing information. Wastewater samples of

    several operations were analyzed to evaluate the possibility of reusing or recycling water.

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  • Most of the mills in this study use large amounts of energy for drying operations and the

    production of steam and hot water. As a result, large amounts of energy are lost through

    stacks and wastewater-s. Where possible, heat recovery opportunities were investigated.

    The information collected at the plants was used to make recommendations to

    management concerning the possible implementations of P2 measures.

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  • CHAPTER 2: LITERATURE REVIEW

    2.1 TEXTILE PROCESSING

    The textile industry includes a variety of processes ranging from the manufacture

    of synthetic fibers and fabric production to retail sales. The first step in the production

    of a textile product is the manufacture of fibers or, in the case of natural fibers, the

    manipulation of these fibers into useful fibers. Afterward, the fibers are turned into yarn

    by spinning or texturing. preparation, dyeing and finishing can be done on yarn or on

    the textile product obtained through knitting, weaving, and non-woven techniques. The

    last step is the fabrication of a finished product.

    The preparation, dyeing and finishing of textile products consume large amounts

    of energy, chemicals and water. These wet-processing operations require the use of

    several chemical baths that, often at elevated temperature, give the desired characteristics

    to the yam or fabric. This section describes the different wet-processing techniques used

    in the production of cotton fabric. The same techniques are used when other types of

    fiber are processed, but differences will occur in the amount of raw materials required.

    Cotton has been chosen for this literature review because 70% by weight of the fibers

    processed in the United States are cotton fibers. Furthermore, processing natural fibers

    requires more processing than manufactured fibers. It is important to know that

    significant differences exist between mills processing the same fabric using the same

    techniques. For example, one mill might operate its rinsing baths at a higher temperature

    than another mill thereby reducing the water consumption.

    2.1.1 Cotton

    The sequence for cotton wet processing is schematically represented in Figure 2.1

    (Snowden-Swan, 1995). These processes are usually done in batch, continuous or semi-

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  • continuous systems. In batch systems, the machine is loa