D. Narasimha Reddy
Environmental Impact of Mechanised and Automated Textile Production Introduction The contribution of mechanised and automated manufacturing to various environmental impacts is enormous. Environmental impacts from manufacturing industries can be seen such areas as toxic chemicals, waste, energy, and carbon emissions. Manufacturing in developed countries is also a heavy user of water, and there have been many cases of air, water and soil contamination which have led to such actions as cleanups, class actions suits and a variety of other corporate liabilities. Environmental impact can be seen in all phases of textile production and use, from growing or making fibres to discarding a product after its useful life has ended. The physical environment is affected by these processes, including resource depletion, pollution and energy use; the biological environment, by considering what happens as a result of manufacture, and the social environment as it impinges on our psychological, physical and physiological comfort, as well as our financial well-being. In recent years, textile industry in developed countries has been facing severe problems, the most serious of which are those connected with pollution. In fact, governments have been bringing up environmental laws which strictly prohibit wastewater discharge in rivers and lakes. This situation indeed burdens the textile industries and also leads to increase in production costs. Textile Industry and Process Description The textile industry includes multiple processes and activities. The four major textile operations are: • • • • Yarn Formation: preparing and spinning raw materials (natural and synthetic); texturizing man-made filament fibers. Fabric Formation: warping and slashing yarn; performing weaving and knitting operations. Wet Processing: preparing the fabric for dyeing and finishing; dyeing, printing, and finishing operations. Product Fabrication: cutting and sewing the fabric, performing final finishing operations.
In the yarn formation process, fibers are bound using spinning operations, grouping, and twisting. Staple fibers, natural and man-made, are prepared for spinning through a combination of various processing steps such as blending, drawing, carding, opening, combing, and roving. Following drying operations, yarn may then be woven into fabric. From the spun or filament yarn, fabric is formed by knitting or weaving operations. Yarn e-mail: email@example.com
D. Narasimha Reddy
can be processed directly through knitting operations but typically requires preparation for weaving operations. Preparation for weaving includes warping and slashing (sizing). Wet processing enhances appearance, durability, and serviceability of the fabric. Chemical Pollution Textile production involves a number of wet processes that may use solvents. Emissions of volatile organic compounds (VOCs) mainly arise from textiles finishing, drying processes, and solvent use. VOC concentrations vary from 10 milligrams of carbon per cubic meter (mg/m3) for the thermosol process to 350 mg carbon/m3 for drying and condensation process. Waste water from processes is a major source of pollutants. It is typically alkaline and has high BOD5 (700 to 2,000 milligrams per liter (mg/L)) and chemical oxygen demand (COD) (approximately 2 to 5 times the biochemical oxygen demand (BOD) level), solids, oil and possibly toxic organics, including phenols (from dyeing and finishing) and halogenated organics (from processes such as bleaching). Dye effluents are frequently highly colored and may contain heavy metals such as copper and chromium. Pesticides used on natural fibers are transferred to effluents during washing and scouring operations. Pesticides are also used for moth proofing, brominated flame retardants for synthetic fabrics, and isocyanates for lamination. Effluents might include pesticides (such as DDT and PCP), and metals (such as mercury, arsenic, and...
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