CP in textile industry
Cleaner Production is a kind of a proactive philosophy and bases on the principle that prevention is better than cure. Therefore different options for CP like housekeeping, changing product, modifying process, substituting raw materials etc are developed. But why invest in CP?
- Improvements to products and processes
- Savings of raw materials and energy and according to this saving of costs
- Increased competitiveness through the use of new and improved technologies
- Reduced concerns over environmental legislation
- Reduced liability associated with the treatment, storage and disposal of hazardous wastes
- Improved health, safety and morale of employees
- Improved image of the company
1. Sources of pollution
In textile industry the largest waste stream is wastewater. In includes washwater from preparation and continuous dyeing, alkaline waste from preparation, and batch dye waste containing large amounts of salt, acid or alkali. Wet processing operations including preparation, dyeing, and finishing generate the majority of textile wastewater.
Types of wastewater include
- cleaning water
- process water
- noncontact cooling water
The amount of used water varies widely in the industry, depending on the specific operated processes, the equipment, and the prevailing management philosophy regarding water consumption. Because of the wide variety of process steps, textile wastewater typically contains a complex mixture of chemicals.
- Air Emissions
Although the textile industry is a relatively minor source of air pollutants compared with many other industries, the industry emits a wide variety of air pollutants, making sampling, analysis, treatment and prevention more complex. Textile operations involve numerous sources of air emissions. Operations that represent the greatest concern are coating, finishing, and dyeing operations. Other significant sources of air emissions in textile operations include resin finishing and drying operations, printing, dyeing, fabric preparation, and wastewater treatment plants. Textile manufacturing can furthermore produce oil and acid fumes, plasticizers, and other volatile chemicals. Acetic acid emissions may come from storage tanks, especially from vents during filling. Carbonizing processes which are often used in wool yarn manufacture, may emit sulfuric acid fumes and decating, a finishing process applied to wool fabrics to set the nap and develop luster, produces formic acid fumes.
- Other Wastes
The primary residual wastes generated from the textile industry are nonhazardous. These include fabric and yarn scrap, off-spec yarn and fabric, and packaging waste. Cutting room waste generates a high volume of fabric scrap that can be reduced by increasing fabric utilization efficiency in cutting and sewing.
2. POLLUTION PREVENTION OPPORTUNITIES
The best way to reduce pollution is to prevent it in the first place. Some companies have creatively implemented pollution prevention techniques that improve efficiency, increase profits and minimize environmental impacts. This can be done in many ways like
- Reducing material inputs
- Re-engineering processes to reuse by-products
- Improving management practices
- Employing substitution of toxic chemicals.
- 1. Quality Control for Raw Materials
Raw material quality control programs can be implemented by establishing specific and appropriate purchasing, packaging, and inventory control policies to prevent the ordering and use of untested materials. Textile companies can reduce waste by working with suppliers to come up with lesspolluting raw materials and by developing purchasing codes that commit companies to using less-polluting raw materials. Benefits of such programs can include decreased production of off-quality goods, less rework, and increased product consistency. Companies can also control raw materials quality by prescreening and testing shipments as they are received. Prescreening provides facilities with opportunities to determine chemical and mechanical alternatives, proper chemical use and training, and proper disposal and treatment methods.
- Adopt environmentally responsible purchasing policies and work with suppliers to obtain less-polluting raw materials.
- Perform tests on raw materials shortly after receipt.
- Purchase raw materials in returnable containers.
- 2. Chemical Substitution
Since textile manufacturing is a chemically intensive process, a primary focus for pollution prevention should be on substituting less-polluting chemicals for textile process chemicals. Chemical substitution can eliminate chemical waste and the need for costly pollution control equipment. Opportunities for chemical substitution vary substantially among mills because of differences in environmental conditions, process conditions, product, and raw materials.
- Replace chemicals with less-polluting ones.
- Replace chemical treatment with other treatment.
- 3. Process Modification
Process changes that optimize reactions and raw materials use can be used to prevent pollution. Modifications may include improved process controlsystems or changes in chemical application methods.
- Use low-liquor ratio dyeing machines.
- Use pad batch dyeing methods.
- Use countercurrent washing to reduce water use.
- Optimize process conditions.
- Combine processes.
- 4. Process Water Reuse and Recycle
Recovery, recycling, and reuse can be effective tools for minimizing pollutant releases to the environment. By recovering solvents and raw materials, textile mills can reduce raw materials costs and can reduce pollution with little modification of existing processes. Water is widely used in the industry for processes ranging from dyeing to preparation and finishing. Raw materials, such as unexhausted dyestuff and additives, can also be recycled. Reuse and recycling are excellent ways for facilities to save money, reduce waste, and save energy.
- Reuse dyebaths.
- Reuse rinse baths.
- 5. Equipment Modification
An additional method to reduce waste is to modify, retrofit, or replace equipment. Some facilities are switching to computer-controlled dyeing systems, which analyze the process continuously and respond more quickly and accurately than manually controlled systems. In many cases, modifying equipment can provide source reduction by reducing the ratio of water and chemicals to textile goods.
- Install automated dosing systems and dye machine controllers.
- Use continuous horizontal washers.
- Use continuous knit bleaching ranges.
- 6. Good Operating Practices
Companies can improve production efficiency and maintain low operating costs by incorporating pollution prevention codes into their management procedures. These codes can include a written commitment by senior management to ongoing waste reduction at each of the company’s facilities and to include pollution prevention objectives in research and new facility design. Establishing training and incentive programs and improving recordkeeping are other ways that companies can prevent pollution without changing industrial processes. These factors, along with better housekeeping practices, can help minimize wastes from maintenance and off-spec materials. Water use can be significantly reduced through minimizing leaks and spills, proper maintenance of production equipment, and identification of unnecessary washing of both fabric and equipment.
- Schedule dyeing operations to minimize machine cleaning.
- Optimize cleaning practices.
- Optimize housekeeping practices.
- Adopt worker training programs.
Reference: EPA Office of Compliance Sector Notebook Project: Profile of the Textile Industry; Office of Compliance and Office of Enforcement and Compliance Assurance U.S. Environmental Protection Agency; Washington DC, September 1997