The textile industry includes a variety of processes ranging from the manufacture of synthetic fibers and fabric production to retail sales. The wet-processing operations, namely preparation, dyeing and finishing of textile products which are used to give the desired characteristics to the yarn or fabric, require the use of several chemical baths. They consume vast amount of energy, chemicals and water. Emissions of volatile organic compounds (VOCs) mainly arise from textiles finishing, drying processes, and solvent use. VOC concentrations vary from 10 mg m -3 for the thermosol process to 350 mg carbon m-3 for drying and condensation process. Process wastewater is a major source of pollutants. It is typically alkaline and has high BOD5 (700 to 2,000 mg l -1 ) 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 wastewaters are frequently highly colored and may contain heavy metals such as copper and chromium. Wool processing may release bacteria and other pathogens. Pesticides are sometimes used for the preservation of natural fibers and these are transferred to wastewaters during washing and scouring operations. Pesticides are also used for moth proofing, brominated flame retardants for synthetic fabrics, and isocyanates for lamination wastewaters may also contain heavy metals such as mercury, arsenic, and copper. Air emissions include dust, oil mists, acid vapors, odors, and boiler exhausts. Towards the search for sustainable industrial enterprises, recent studies indicated that there are many cleaner (sustainable) production opportunities which lead to waste reduction as well as increased raw material use efficiency in textile wet processing industry. The relevant reduction/conservation strategies, process modifications, chemical substitutions and reclamation/reuse techniques which reduce the wastes (air, water and solid/hazardous) originating from preparation, dyeing, printing, finishing, and other sources in textile mills were reported. The objective of this chapter is to: (a) provide an environmental profile of the wet textile industry, (b) review cleaner (sustainable) production opportunities in textile wet processing industry, and (c) report the progress obtained in the textile demonstration project in the context of the UNIDO Eco-efficiency (cleaner production) project which has been implemented in Turkey since 2008. \textcopyright 2012 Nova Science Publishers, Inc. All rights reserved.
|State||Published - 2012|