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'i

Industrial Pollution

Prevention Handbook

Harry M. Freeman

McGraw-Hill, Inc. New York San Francisco Washington, D.C. Auckland Bogot6

Caracas Lisbon London Madrid Mexico City Milan Montreal New Delhi San Juan Singapore

Sydney Tokyo Toronto

Other McGraw-Hill Environmental Engineering Books

American Water Works Association WATER QUALITY AND TREATMENT

Baker BIOREMEDIATION

Chopey ENVIRONMENTAL ENGINEERING FOR THE CHEMICAL PROCESS INDUSTRIES

Corbitt STANDARD HANDBOOK OF ENVIRONMENTAL ENGINEERING

Freeman HAZARDOUS WASTE MINIMIZATION

Freeman STANDARD HANDBOOK OF HAZARDOUS WASTE TREATMENT AND DISPOSAL.

Jain ENVIRONMENTAL IMPACT ASSESSMENT

Harris and Harvey

COMPLIANCE WITH SARA TITLE I11 HAZARDOUS CHEMICALS AND THE RIGHT TO KNOW: A N UPDATED GUIDE TO

Levin and Gealt BIOTREATMENT OF INDUSTRIAL AND HAZARDOUS WASTE

Kolluru ENVIRONMENTAL. STRATEGIES HANDBOOK

McKenna and Cunneo PESTICIDE REGUMTION HANDBOOK

Majumdar REGULATORY REQUIREMENTS OF HAZARDOUS MATERIALS

Seldner ENVIRONMENTAL DECISION MAKING FOR ENGINEERING AND BUSINESS MANAGERS

Waldo and Hines CHEMICAL HAZARD COMMUNICATION GUIDEBOOK

Willig ENVIRONMENTAL TQM

50 Pollution Prevention

in the Textile Industries

Lesley J. Snowden-Swan Battelle Pacific Northwest Laboratories

Richland, Washington

50.1 Industry Overview From the ancient handweaving of linen mummy cloths for Egyptian tombs and fine silk gowns in China to turning out designer blue jeans in mass quantities to the manufacture of fiber-reinforced composites for the Mars mission, the production of textile products has prevailed throughout the centuries. In today's industrial setting, the basic principles of textiles are much the same, but the practice of crafting textiles has grown to become one of the major industries in the United States and abroad. The United States textile industry, including fiber production, fabric production, and apparel workers employs 1.7 million workers, accounting for one of every 11 jobs.'

In its broadest sense, the textile industry includes fiber, fabric, and apparel production, and retail sales. Generally, production includes the following steps:

1. Generation of a usable fiber from either a natural source (Le., cotton, wool, and silk) or from a manufactured source (polyester, rayon, and nylon)

2. Production of yarn for knitted and woven fabrics 3. Construction of product through knitting, weaving, and nonwoven or other

Pollution Prevention in the Textile Industries 83 1

ing steps between key treatment steps. Consequently, large volumes of wastewater are generated with a very diverse range of contaminants that must be treated prior to disposal; much energy is consumed to heat and cool chemical baths and washwater and to dry fabrics or yarns.

Not surprisingly, the industry has faced increasing pressure regarding environmental and waste-related concerns as a result of the quantity and toxicity of generated wastewaters; this was illustrated in 1989 when the industry was listed among the top ten toxic waste generators in the United States Environmental Protection Agency TRI report6 (for 1987 releases), the majority of toxics (52%) being released to water media. The industry has since made sig- nificant reductions in waste generation through equipment changes, recycling, and non-process-related measures such as housekeeping, as well as research and development activities centered on technology for waste minimization. Specific examples of these activities are discussed in Secs. 50.4 and 50.5.

Recent developments in the industry are providing for more recycle and reuse of process water and chemicals. Furthermore, interest in media other than the traditional water-based systems, such as solvents and foams, for chemical application is increasing. Accordingly, the industry is finding that, beyond meeting regulations, the potential economic gain through reductions in treatment costs and wasted resources is enormous.

Waste reduction efforts can involve process-related solids (primarily fiber and yarn spinning waste, fabric cutting waste, fly ash from burning of fossil fuels, sludge from wastewater treatment facilities, and packaging materials) and air pollution (i.e., volatiles such as formaldehyde and ammonia emitted during flame-retardant finishing7), as well as waste from non-process-related activities. However, the largest impact, especially with respect to water pollution, may be made in the wet-processing operations, primarily those steps taken after the construction of unfinished fabric (commonly called gray goods), because these operations are the most water- and energy-intensive and potentially the greatest waste-generating part of the textile i n d ~ s t r y . ~

The following sections describe preparation, dyeing/printing, and finishing operations; the primary wastestreams generated; feasible pollution prevention strategies that are currently available; and success stories demonstrating selected strategies.

50.2 Process Description Because there is such a diverse product and application range of textiles today, the type of processing used is highly variable and depends on site-specific manufacturing practices, as well as on the type of fiber used and the final physical and chemical properties desired. These properties include tensile strength, flexibility, uniformity, and luster. Even for a constant product type, no two textile mills use exactly the same methods of production. Figure 50-1 shows the typical sequence for the minimum wet-processing steps taken for cotton-con-

832 Chapter Fifty

knits enter here

material from weaving

Mercerize

knits

Dyeing Pad

(Continuous dyeing)'

Pre-drying

white cotton or blend fabric

Prediying & I Drying l-

Printing -+o __..)

Finished

I

- I

fabric Heatset

Figure 50-1. Typical process for pretreatment, dyeing, and finishing of cotton and cotton-blended fabrics. (Note that batch, rather than continuous dyeing, is normally used for knits.)

taining (100 percent and cotton-blended) woven fabrics, and will be the focus of the remaining discussion. Variations in this sequence are indicated in Fig. 50-1 for knits, whites, and manufactured fibers. In general, natural fibers receive more processing than manufactured ones to achieve the same product performance.

The common systems used for processes shown in Fig. 50-1 include batch, continuous, and semicontinuous equipment setups. In batch setups, a fixed amount of substrate (cloth, yarn, etc.) is placed in the machine, chemical solution is introduced, and processing proceeds. After the reaction is finished, substrate is removed and chemical solutions are discharged (or reused, if feasible), with any subsequent auxiliary processes (rinsing, washing, etc.) occurring in the same vessel. In continuous systems, chemical solution is placed in the machine and fabric is moved through it without interruption. Because batch systems inherently tend to generate more waste than continuous systems, batch systems are generally used for treating (i.e., dyeing) small quantities of a par-

Pollution Prevention in the Textile Industries 833

ticular type of product, while continuous systems are more amenable to processing large yardages of product. Further description of the three major phases of wet processing is given to provide information on the wastestreams generated.

50.2.1 Fabric Pretreatment

As shown in Fig. 50-1, the minimum aqueous processing for cotton-containing woven fabric preparation prior to dyeing includes desizing, scouring, bleaching, and mercerizing. Desizing, scouring, and bleaching can be carried out in either batch or continuous modes. In continuous operation, fabric is immersed in solution, moved to a heated reaction chamber, and washed off in a series of wash boxes after reaction completion. In batch operation, the reaction actually occurs while the fabric is immersed in the treatment bath. Typically, the vessel is drained, and neutralization and washing are carried out in the same vessel.

Fabric coming directly from the loom or knitting machine usually contains impurities. For wovens (only), the major impurity is generally a warp-sizing compound, material applied to the yarn during the slashing step to minimize yarn damage from abrasion and to maximize weaving efficiency. The sizing is a film-forming stiffening agent, such as starch, carboxymethyl cellulose (CMC), or polyvinyl alcohol (PVA). PVA is becoming increasingly popular because, unlike starch, it remains intact during desizing and can therefore be recovered and reused. However, current recovery and reuse of PVA is primarily found in large vertically integrated companies where the weaving and preparation operations are geographically collocated. In desizing, fabric is treated with a compound that is complementary to the sizing agent previously used. Typically, enzymes are used as reducing agents, and the system is run at elevated temper- atures to increase the speed of the process. The fabric is then washed com- pletely to remode the impurities.

Next, the cotton cloth is treated with hot caustic solution in the scouring process in order to remove substances such as pectin, wax, and other impurities present in natural fiber. Other compounds necessary for removal include yarn spinning and knitting lubricants (for knits only). Impurities are removed from fabric for processing reasons and/or because they cannot be released to the retailer /consumer. For aqueous scouring, there are a variety of chemicals used, including sodium hydroxide, detergents, and occasionally solvents for treating manmade fibers. Fabric is then thoroughly washed to remove scouring solution.

After scouring, essentially all cellulosic-containing fabrics are bleached even if they will eventually be dyed or printed another color. Bleaching provides a uniform white surface for dyeing and /or printing. The majority of bleaching operations (more than 95 percent) use hydrogen peroxide (H,O,), while the rest use calcium hypochlorite. Peroxide bleaching is favored by the industry because it is cost-effective and noncorrosive to processing equipment as well as being a safe and environmentally sound alternative to other chemicals. It has

834 Chapter Fifty

also been suggested that less washing is required after peroxide bleaching for removing the reaction s ~ l u t i o n . ~

The last step of aqueous processing for cotton woven fabric preparation is mercerizing, which is always carried out in continuous mode. In this process, the fabric is held with or without tension while being saturated with caustic solution. This method results in a desirable change in the physical and chemical properties-in particular, luster, dyeability, strength, and smoothness. Like fabrics, yarns may also be mercerized before fabric construction. Again, the fabric is rinsed thoroughly under tension after mercerizing is finished.

50.2.2 DyeingPrinting

After preparation, color is applied to fabric through dyeing and/or printing. There are three primary mechanisms for applications of dyes to fiber, yarn, or fabric: (1) chemical reaction with the fiber molecules, (2) attachment to the fiber surface, or (3) absorption into the fiber with no reaction. Dye categories include acid, azoic, basic, direct, disperse, pigment, reactive, solvent, sulfur, and vat dyes. Most commonly in use today are the reactive and direct types for cotton dyeing, and disperse types for polyester dyeing. Direct and fiber reactive dyes have a fixation of 90 to 95 percent and 60 to 90 percent, respectively, while disperse dye is 80 to 90 percent. Individual dyes possess unique chemical characteristics that are suitable for a specific type of fiber, a desired color and quality of the dyed material, the type of equipment to be used, and other considerations.

For some applications, the fiber (stock dyeing) or yarn (package and skein) is dyed prior to fabric construction, or the garment is completed prior to dyeing. However, piece dyeing is most widely used because it is the simplest and least costly method. Piece dyeing also allows manufacturers to color fabrics as ordered, rather than stockpiling and having to risk changes in customer prefer- ences. Methods for piece dyeing include beam, beck, jet, and jib processing, all of which are batch processes, and pad dyeing, which can be either a batch or continuous setup. Typically, in batch (exhaust) dyeing, scouring (see Sec. 50.3) and rinsing are carried out after dyeing to remove all excess dye and chemicals from the fabric. The majority of the dyeing machines in use today are exhaust processes; however, continuous dyeing accounts for about 60 percent of the total yardage of product dyed in the industry.

Of the numerous printing techniques used for commercial production, the most common is rotary screen, but others such a s directi discharge, resist, flat screen (semicontinuous), and roller printing are often seen commercially. Sometimes washing with hot water and detergent is required for "wet printing''; however, for "pigment printing," which comprises approximately 75 to 85 percent of all printing operations, washing is not required. One method developed in the OS, transfer printing, requires no cleanup and generates little or no waste. Currently, this technology is practical for 100 percent polyester fabric only, and thus is viewed as having limited potential in the future. The


application of foam technology to printing has also been demonstrated, the main advantage again being reductions in water and energy consumption.

50.2.3 Finishing

The primary purpose of the finishing process is to apply chemical moieties to the fabric in order to alter properties affecting the care, comfort, durability, environmental resistance, aesthetic value, and human safety associated with the fabric. Finishes include a very large and diverse group of chemicals ranging from antistatic to shrink-resistant to flame-resistant treatments; the most common are those which ease fabric care, specifically the permanent-press, soil- release, and stain-resistant finishes. In wet-finishing, the sequence of steps typically includes chemical finish application, drying, curing, and cooling. Most finishing employs chemical application together with mechanical techniques, the advantages of the latter being improved feel, strength, and abrasion resistance and lower chemical consumption and waste. Developments in low add- on technology and other application methods are in progress.

50.3 Primary Wastestreams The principal wastestream of concern is water containing natural impurities and processing chemicals (Tables 50-2 to 50-4). Wastewater composition is highly variable due to the wide range of treatments used in batch processing. Generally, wastewater is colored, highly alkaline, high in BOD and COD, and at elevated temperature. Also of particular concern are more specific com-

Table 50-2. Waste Characteristics for Fabric Preparation Operations

Process Purpose Species in bath/washwater

Desizing of wovens

Scouring (for cotton Remove natural only) impurities and han-

dling contaminants

Remove size applied for weaving

Bleaching Decolorize natura! pigments and enhance uniformity of color adsorption

Mercerizing (for Improve fabric’s cotton only) chemical/physical

properties

Enzymes, degraded starch (high BOD), or, alternatively, PVA NaOH; chelating agent for Fe; detergents; fats; oils; pectin; wax; cotton seed, stems, and leaves; knitting lubricants; spin finish H,O, (most comm-on). sodium silicate or organic stabilizer, sodium hydroxide, surfactants, chelates, sodium car- bonate; possibly antichlor (for wool) like sodium peroxide NaOH (16-24% solution)

Disperse

pounds that are toxic to aquatic life, such as heavy metals, primarily from dyeing and finishing (and water impurities), surfactants (wetting agents), compounds used throughout the wet-processing steps, and other process chemicals. Fabric rinsing and/or washing (using detergent) is usually performed between primary process steps, resulting in large quantities of dilute wastewater in excess of spent chemical baths.

The following sections describe wastewaters from individual steps within fabric pretreatment, dyeing, and finishing.

Pollution Prevention in t he Textile Industries 837

50.3.1 Fabric Pretreatment Waste

With the numerous process steps that are potentially involved in fabric preparation, wastewaters may contain a complex mixture of chemicals. The desizing step is of particular concern, contributing up to 50 percent of the BOD load in wastewaters from wet processing.’ Presented in Table 50-2 are typical chemical characteristics of pretreatment effluents.

50.3.2 Dyeinprinting

Of the 700,000 tons of dyes produced annually worldwide, approximately 10 to 15 percent of the dye is disposed of in effluent from dyeing operations.loJ1 For one dyehouse recently characterized,I2 as much as 50 percent of the dye origi- nally present in the fresh dyebath was discharged after dyeing of synthetic fibers. Wastewater generation from a typical dyeing facility is estimated at 1 to 2 million gallons per day. Including the dyeing, postscouring, and rinsing processes, approximately 12 to 17 gallons of wastewater per pound of product are produced for disperse dyeing, while 15 to 20 gallons per pound is more typical for direct and reactive dyeing. The primary source of wastewater is spent dyebath and washwater, which contain by-products (hydrolyzed dye), some intact dye, and auxiliary chemicals. In addition to process water and chemicals, a major source of toxic pollutants in wastewater is cleaning solvents used in dyeing and printing machine cleaning, such as oxalic acid, hydrochloric acid, and carbon tetrachloride.

With the abundance of individual dyes and the wide range of dyeing equipment in use today, it is difficult to summarize wastestream characteristics. In general, wastewater from batch dyeing is high in volume and pollutant load, and tends to contain heavy metals, aromatics, and halogenated hydrocarbons from the dyebath makeup. All are toxic to aquatic life.12 In addition to the dyestuff itself, many auxiliary chemicals are used to aid in dye transfer; the majority of these chemicals, including unreacted color, are discharged with the spent bath.

In the most commonly used technique, pigment printing, the main source of waste is from the cleanup, during which unused printing paste is removed from the screen. Consequently, proper planning of paste use and housekeeping are major issues in minimizing waste in printing operations.

Table 50-3 lists chemical characteristics of waste effluent from exhaust dyeing of cotton (direct and fiber reactive) and polyester (disperse) products.

5 0.3.3 Finishing

As with the dyeing operations, finishing methods are highly variable, due to the broad range of finishes available. Pollutants in wastewaters include natural and synthetic polymers, and a range of other potentially toxic substances. Table 50-4 shows a few common finishes used and serves to illustrate the wide variety of chemicals that may be present in finishing effluent.


ing, along with specific examples of each are presented in Tables 50-5 through 50-7. A more thorough description of each technique is found in the referenced documents and the list of further reading.

As shown in Table 50-5, material change strategies have focused on decreased toxicity, increased recoverability, and improved efficiency of reac- tions. When the complete textile product life cycle is considered, it is apparent that chemical suppliers (for fibers, dyes, and auxiliaries) have a tremendous influence on the environmental impact of textiles manufacturing. In fact, there is increasing pressure from the textile mills on their suppliers to improve product performance via increased exhaustion and efficiency of dyes, less toxic and fewer auxiliary chemicals needed, and low-volatile and permanent finishes.I2

Table 50-6 gives process modification strategies to aid in minimizing wastestreams. Process change methods have focused on advanced dyebath

Table 50-5. Material Change Strategies in Wet Processing

Option Example Benefit

Alternate desizing agents 1. H202 rather than enzyme for desizing of starch14

2. Enzymes that de rade starch to ethanol *$

Bleaching agent Alternate dyes 1. Copper-free for produc-

ing green shades in 100% cotton fabric15

tives such as with RemazolTM (9598% fixation w / pad / ba tch)I5 and others

3. High-temperature reactive (such as ProcionTM) for simultaneous application of disperse and reactive dyes4

1. Substitute for phosphates such as acetic acid (pH control) and EDTA (water ~onditioner)’~

2. New washing agents (such as Sandpure S K T M and others)’5

2. Improved fixation reac-

Substitute auxiliaries (all processes)

Resulting products of CO, & H,O over hydrolyzed starch using enzymes (less BOD in wastewater) Reduced BOD of spent desizing bath and opportunity to recover ethanol as fuel Increased wash efficiency (less water needed) Reduced toxicity (metal content) of spent dye bath and washwater

Less unreacted and hydrolyzed (degraded) dye in spent bath and washwater improves reuse opportunities

Energy reduction, elimination of caustic bath required after disperse dyeing

Reduction in phosp’norus load in wastewater

Increased wash efficiency, and thus decreased water consumption and improved fastness of reactives

840 Chapter Fifty

Table 50-6. Process Change Strategies in Wet Processing

Option Example Benefit

Pad-batch dyeing

Low liquor ratio dyeing

Foam technology

Spraying technology

Washing technology

Process consolidation

Transfer of dye to cotton, rayon, and blended goods through rollers (continuous method)14 Reduction in the weight of water (solution) used to dye a iven weight of

Application of dye through foam media (air dispersed in l i q ~ i d ) ~ , ' ~ or other solvents for dyeing and printing (finishing and preparation) Application of finishes using sprays4 Countercurrent washing, vibrating-reed jet washers, mechanical means for increased turbulence' Single pad-steam-wash sequence using unique com- binations of

goods f14

Reduction in water (2 gal/lb vs. 2C energy (2000 vs. 9000 BTU/lb) anc use, increased productivity

Improved dye fixation, large redut energy and water consumption in (but not necessarily in subsequent steps) Reduced water and energy consum chemical waste, and time necessary

Reduced energy and water usage, ical waste (most finish remains on Improved washing efficiency, thu: water and energy usage

Decreased water and energy usag effluent, and process times

techniques for aqueous processing, alternative application media and delivery, and improved washing efficiency. In addition, overall strategies such as com- bining individual process steps into one step offers perhaps a more systematic and holistic approach to minimizing waste.

Table 50-7 gives specific strategies feasible for reclamation of process water and chemicals. Inherent in water conservation is the added benefit of reduced consumption of secondary resources such as electricity for drying and pumping, fossil fuels used for steam generation, and cooling water. Furthermore, water that has been treated and recovered is generally more valuable than freshwater (less impurities), providiilg even more economic incentive io recycle options. Recent advances in membrane technology and other treatment schemes have focused on nondestructive treatment to allow recovery, providing improved alternatives to common wastewater treatment methods used in the past (chemical precipitation, trickling filtration, and biological treatment and aeration), which have not necessarily enabled resource recovery.

Along with the specific reuse opportunities listed in Table 50-7, accurate and automated chemical analysis of spent bath and wastewaters is considered

Pollution Prevention in the Textile Industries 84 1

Table 50-7. Recovery and Reuse Strategies for Wet Processing

Option Description Benefit

Size" recovery Separation/concentration (after desizing) of PVA size by ultrafiltra-

tion (or reverse osmosis) for r e u ~ e ~ ~ J ~ J ' With low hydrolysis of dye molecules, dyebaths may be recharged with bath chemicals and reused repeatedly14 Recycling of NaOH mercerizing solution up to 98%14

Dyebath reuset

Caustic recovery

Metal reuse Treatment of exhausted dyebath w/biological, chemical coagulation, membrane separation technology to remove and recover metals and water

Reduced BOD load in effluent, and freshwater and chemical consumption

Decreased pollutant load in effluent, freshwater, and chemical consumption

Reduced alkalinity of wastewater from pretreatment and chemical consumption Reduced freshwater and metals consumption, and toxicity of effluent

*Also involves material substitution (e.g., PVA or similar agent) in the sizing process to enable

tDyebath analysis tends to be difficult with reactive type dyes due to the difficulty of differenti- subsequent recovery.

ating unhydrolyzed and intact colorant using spectrophotometry.ls

essential for providing more opportunities for implementation of pollution prevention measures. For example, the feasibility and effectiveness of dyebath reuse increases dramatically if an accurate and timely analysis of used dyebath composition is available for calculating the amounts of makeup chemicals needed to refresh and reuse the bath.

50.4.2 Future Strategies

Until the last year or two, research and development (R&D) efforts addressing environmental matters have been minimal. It is now evident, however, that advanced technology will be essential to the future of the textiles industry. Examples of research and development efforts underway are:

Sizes able to be removed in cold water for later reuse and sizes that are permanent (no removal necessary, function as dyesitesP Gaseous reactants for bleaching, including 0,, singlet oxygen, or vapor phase reaction^,^ resulting in reduced aqueous waste and energy and water consumption

842 Chapter Fifty

Ultrasonic waves in dyebath to increase dye uptake by threefold Electrostatic application of powdered chemicals for printing and finis he^,^,'^ resulting in water and energy conservation and reduced effluent volume

Application of overlapped colors of powdered pigments and binders to fabric, using a process similar to color xerographic methods,l2 resulting in reduced water consumption and effluent volume

m The application of ink-jet printing, a noncontact method of propelling very small droplets of ink onto a surface, to textile products19 Fiber modification through surface-photografted (and other grafting methods) synthetic fibersz0 resulting in enhanced dye absorption and less wasted dyestuff

More overall changes in the production infrastructure may be likely as well. For example, integrating automation into every aspect of production, including everything from dyebath chemical analysis and reuse to garment fabrication, is a major topic of interest and effort within the industry. An essential aspect of automation is demand activnted manufacturing (quick response), which will hold high importance in the future. An example is the coloring of preassembled items to order rather than carrying a large inventory."

Increased vertical integration of individual functions is also desired, as closely coupled manufacturing processes tend to maximize control and energy and water efficiency, chemical recovery, and production rate. In the future, synergistic relationships will be identified between different industries, and facilities will be built in close geographical location to strive for complete closed-loop systems.

In its efforts to improve operations, the industry has recently reached out into other sectors of the research community. Just recently formed is the American Textiles (AMTEX) Initiative, a cooperative research agreement between the United States Department of Energy (national research labs) and numerous organizations from the textiIe industry and academic sectors. This agreement has facilitated collaborative research in many aspects of textile manufacturing that are important to enhancing the global competitiveness of United States textiles, incorporating pollution prevention and waste minimization technology.

Case Studies

Chemical Substitution of Sulfides2' One textile facility that uses sulfur dyes has investigated possible substitutes for sodium sulfide, which is used to convert water-insoluble dyes to the solu- ble (lueco) form for application to materials. After several attempts at substitutes, the facility found that they could replace 100 parts sodium sulfide with


65 parts alkaline solution containing 50 percent reducing sugars plus 25 parts caustic soda. As a result, sulfide levels in the effluent from this process have dropped substantially (below 2 ppm).

Recovery and Reuse of Rinse Baths22 Through the implementation of recycle schemes for process water used to remove mercerizing solution, a yarn finishing company has drastically reduced pollution load in wastewater, and soda (Na,CO,) and caustic consumption. The new process involves reusing the rinse bath three times over rather than using three separate volumes of rinsewater in series. The spent rinsewater is then processed in an evaporator and concentrated caustic is reused in mercerizing. The result of the process changes was an 80 percent reduction in suspended solids, 55 percent reduction in COD, and 70 percent reduction in neutralizing soda in the wastewater. Corresponding reductions in hydrochloric acid used to neutralize the effluent were experienced as well. The investment in new equipment resulted in an annual savings of $189,000, with a payback of under one year.

Reuse of Nonprocess and Process Water and Automated Chemical Addition for Dyeing23 In efforts to reuse both noncontact cooling water and contact production water used in the dyeing process, an acrylic yarn producer has realized tremendous savings of water, energy, chemicals, and reduced waste generation. The facility has reduced its water consumption from 320,000 gallons per day to 102,000 gallons per day and simultaneously increased production from 12 to 20 batches per day. Additionally, energy consumption for heating dyebath has decreased substantially. The investment has resulted in a savings of approximately $13,000 a month and paid for itself in 30 days after implementation.

In addition to water reuse, the company has implemented computer technology to automate dyebath flow and temperature in a new facility. With the computer program, addition of auxiliary chemicals (retarders and leveling agents) is precisely controlled, resulting in a clean exhausted dyebath; this eliminates the need for postrinsing and thus reduces amounts of water and chemicals consumed and wasted.

References 1 .

2.

3.

People in the U.S. Textile industry, employment statistics for 1990, prepared by the American Textile Manufacturers Institute, Washington, D.C. Norma Hollen, Jane Saddler, Anna L. Langford, and Sara J. Kadolph, Textiles, 6th ed., Macmillan, New York, 1988. Peyton B. Hudson, Anne C. Clapp, and Darlene Kness, Joseph's Introductory Textile Science, Harcourt Brace Jovanovich, Fort Worth, 1993.

844 Chapter Fifty

4. Joseph S. Badin and Howard E. Lowitt, The US. Textile Industry: An Energy Perspective, DOE/RL/01830/T-56, prepared by Energetics, Inc. for Pacific Northwest Laboratory, Richland, Wash., 1988.

5 . Energy Conservation in the Textile Industry Phase I t3 II,ORO-5099-T1 /T2, prepared by the Georgia Institute of Technology, 1977/78.

6. “Textiles Ranks Sixth in Toxic Waste,“ Textile World News, August 1989, pp. 23-25. 7. David Gent, “A Novel Approach to Practical Problems,” Journal of The Society of

Dyers and Colourists, 108:306-307 (1992). 8. Fred C. Cook, “AATCC Invades Boston with Environmental Ammo,“ Textile World,

September 1990, pp. 67-70. 9. W. B. Achwal, “Environmental Aspects of Textile Chemical Processing (Part I),”

Colourage, October 1990, pp. 4042. 10. Jack T. Spadaro, Michael H. Gold, and V. Renganathan, ”Degradation of Azo Dyes

by the Lignin-Degrading Fungus,” Applied and Environmental Microbiology,

11. H. Zollinger, Color Chemistry-Syntheses, Properties and Applications of Organic Dyes and Pigments, VCH Publishers, New York, 1987.

12. Mervyn C. Goronszy, and H. Tomas, ”Characterization and Biological Treatability of a Textile Dyehouse Wastewater,” 47th Purdue Industrial Waste Conference Proceedings, Lewis Publishers, Inc., Chelsea, Mich., 1992.

58(8):2397-2401 (1992).

13. Facility Pollution Prevention Guide, EPA/600/R-92/088, May 1992. 14. Brent Smith, A Workbook for Pollution Prevention by Source Reduction in Textile Wet

Processing, available from the Pollution Prevention Pays Program, North Carolina Department of Environment, Health, and Natural Resources, Raleigh, N.C., 1988.

15. Fred C. Cook, ”Environmentally Friendly: More than a Slogan for Dyes,” Textile World, May 1991, pp. 84-89.

16. Fred C. Cook, ”Fabric Processes Beholden to Energy, Environment,” Textile World, November 1990, pp. 49-54.

17. J. D. Nirmal, V. P. Pandya, N. V. Desai, and R. Rangarajan, “Cellulose Triacetate Membrane for Applications in Plating, Fertilizer, and Textile Dye Industry Wastes,” Separation Science and Technology 27(15):2083-2098 (1992).

18. Fred C. Cook, ”QR, Environmental Pressure Will Drive Dyeing, Printing,” Textile World, December 1990, pp. 83-85.

19. Brent Smith and Elizabeth Simonson, ”Ink Jet Printing for Textiles,” Textile Chemist and Colorist, 19(8):23-29, August 1987.

20. Zhenguo Feng, Magdalena Icherenska, and Bengt Ranby, “Photoinitiated Surface Grafting of Synthetic Fibers, IV: Applications of Textile Dyes onto Surface- Photografted Synthetic Fibers,” Die Angezuandte Madromolekulare Chemie, 199:33-44 (1992).

21. Case Study for Century Textiles and Industries Limited (Bombay, India), available from Waste Reduction Resource Center, Raleigh, N.C..

22. Michael R. Overcash, Techniques for Industrial Pollution Prevention, Lewis Publishers, Chelsea, Mich., 1986, p. 168.

I /

Pollution Prevention in the Textile Industries 845 I

I

~

23. Case Study for Amital Spinning Corporation, available from Waste Reduction Resource Center, Raleigh, N.C.

Further Reading Badin, Joseph S., and Howard E. Lowitt, The U.S. Textile Industry: An Energy Perspective,

DOE/RL/01830-T56, prepared by Energetics, Inc. for Pacific Northwest Laboratory, Richland, Wash., 1988.

Smith, Brent, Identification and Reduction of Pollution Sources in Textile Wet Processing, available from the North Carolina Pollution Prevention Pays Program, Department of Environment, Health, and Natural Resources, Raleigh, N.C., 1986.

Smith, Brent, A Workbook for Pollution Prevention by Source Reduction in Wet Textile Processing, available from the North Carolina Pollution Prevention Pays Program, Department of Environment, Health, and Natural Resources, Raleigh, N.C., October 1988.

Acknowledgments

This work was supported by the U.S. Department of Energy under Contract DE-AC06-76RLO 1830. Dr. Brent Smith of the College of Textiles at North Carolina State University provided a technical review and contributed much useful information to this section.

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