tailieunhanh - Membranes for Industrial Wastewater Recovery Episode 7

Tham khảo tài liệu 'membranes for industrial wastewater recovery episode 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 1 3 2 Membranes for Industrial Wastewater Recovery and Re-use The textile industry Categories of textile processing operations Textile industry processes comprise those which convert natural . cotton wool silk etc. and synthetic . viscose polyester acrylic fibres into fabrics and other products. Four key activities can be identified within this industrial sector Mattiolieta . 2002 the treatment of raw materials preparation production of textile fibres yarns the production of knitted woven fabrics the finishing of fabrics . changing some physical property of the fabric to meet the end use requirement and production of products . garments carpets etc from the fabric. In 1998 world trade in textiles was worth approximately 370 billion or about of global merchandise trade WTO 1998 . USA textile exports account for 19 billion and imports principally from Mexico and China around 77b. Around 60 of textile production takes place in Europe 29 and the Americas with most of the remaining production taking place in Asia Stengg 2001 . Within the European Union which is characterised by a large number of small-to-medium enterprises Italy accounts for 31 of all textile and clothing manufacturing activities - more than double that of the UK 15 Germany 14 or France 13 . Most of this activity is accounted for by clothing manufacture. A number of textile manufacturing processes are chemical wet processing operations necessary to properly prepare purify colour or finish the product. This results in the production of wastewater whose pollution load arises not only from the removal of impurities from the raw materials but also from the residual chemical reagents used for processing. The freshwater demand is specific to the type of textile processing operation the type of material or final product and the specific machine or technique used. However the water demand for wet processing operations is invariably high Table 9 more than 5000 m3 day-1 for a large .