pollution prevention in textile dyeing n printing

Pollution Prevention Through Automation in Textile Dyeing and Printing Textile wet processing (i.e. preparation, dyeing, printing and chemical finishing) has always been considered one of the worst industrial sectors in terms of water consumption and pollution. In treating 1 ton of cotton fabric the composite waste stream may have 200-600 p.p.m. BOD, 1.000 to 1.600 p.p.m. of total solids and 30 to 50 p.p.m. of suspended solids contained in a volume of 50 to 160 m3. For wool the effluent load is even higher, for 1 ton of scoured wool the composite waste stream would have 430 to 1.200 p.p.m. BOD and around 6.500 p.p.m. total solids contained in a volume of 100 to 230 m3. Many textile companies invest - or plan to invest - heavily in effluent treatment, in many cases not knowing that the pollution load may be reduced by 30-50% by applying techniques of pollution prevention, such as: reduction of wastewater volume by good housekeeping, counterflow processing, reuse of process water, automation of the machinery reduction of the amount of dyes and chemicals used by good housekeeping process optimization recovery and reuse of process chemicals, automation of the machinery computerized recipe optimization When we speak about automation in textile dyeing and printing, we mean one or more (or all) of the following steps: Programmable process control (by microprocessors) of the machinery; dissolving and dispensing of the dyes, pigments and chemicals in a central colour kitchen; computer-controlled weighing of solid material with automatic stock control and the printing of recipe and process cards; colour measurement, computerized colour matching; central computer (network), computerized management system Which of the above, and in what order, should be implemented depends a great deal on what is the purpose of automation. In order to improve the quality a) and c) are the most important, to save man-power a) and b) would be recommended, while for cost reduction d) is far the most efficient. If our aim is better service to our customers: right-first-time production, quick response to the client's request and just-on-time delivery, we have to implement full automation from a) to e). When our goal is pollution prevention, every automation step helps, but the first four of the list above would bring the most immediate results. Programmable process control (by microprocessors) of the machinery Full control of the processes results in 10-30% saving in water and energy usage as well as 5-15% saving in dyes and chemicals (in addition to significant saving in labour, and improvement in quality). Dissolving and dispensing of the dyes, pigments and chemicals in a central colour kitchen. 5-10% savings in dyes, pigments and chemicals (in addition to significant saving in labour, and improvement in quality). Computer-controlled weighing of solid material with automatic stock control and the printing of recipe and process cards. 10-15% savings in dyes, pigments and chemicals (in addition to significant improvement in quality). Colour measurement, computerized colour matching Up to 30-40% savings in dyes and pigments (in addition to significant improvement in quality). Needless to say, all the dyestuffs, pigments and chemical products "saved" by any of the above mentioned methods are also saved from the effluent. The greatest attraction of pollution prevention through automation is the simultaneous result of significant cost savings both in the production and in the effluent treatment. The costs of automation are relatively low, typical Return of Investment figures are in the range of 3 months to 1 year, not calculating the quality and reliability improvements, and neither the savings achieved in investing in and running a smaller effluent treatment plant.