Zero Discharge Of Effluent From Textile Industry

Abstract

Water-Pollution control is presently one of the major areas of scientific activity. In the present scenario of environmental pollution, particularly water pollution, textile industries are facing serious problems in effluent treatment. The textile industry typically uses large quantities of water, it being water intensive industry and generates large quantities of the effluent ranging from as low as 5000 liters/hr to as high as 3,00,000 liters/hr which contains various objectionable impurities such as Color, COD, BOD, TDS etc. After imparting suitable treatment with the conventional treatments, these effluents are being discharged into the receiving bodies. In recent times, Compliance of ‘Zero Discharge’ requirement, in which, the industry is not supposed to discharge any effluent outside its premises is really a very tough requirement from the techno-economic viewpoint. Various conventional technologies such as Reverse Osmosis, Incineration, Multiple-Effect Evaporation, Solar Evaporation etc are intrinsically and techno-economically unsuitable for sustained, long-term compliance of ‘Zero Discharge’ at Industrial Scale. Besides, they are far too expensive and are prone to frequent maintainance problems and resultant degradation of their efficiency. This project deals with the newer approach to ‘Zero Discharge’ which genuinely and techno-economically ensures ‘Zero Discharge’ without suffering from the deficiencies of the conventional technologies as outlined above. The two types of synthetic textile effluent of 0.1 %, 0.3%, & 0.5% w/v dye solution were used and were characterized. The ‘Zero Discharge’ system pilot plant developed at ATIRA convert the liquid into vapor which gets evaporated naturally without heat input and separates dissolved solids from the wastewater as a by-product powder that can be reused. Initially the wastewater from the storage tank is pumped into the duct wherein it gets split into water droplets of 50-100 micron size with the help of high pressure system placed into the duct. These water droplets are kept airborne for the natural evaporation to occur with the help of air provided from the bottom of the duct with the help of air blower. The Batch and Continuous study were performed wherein (i) The net water evaporated in an hour, (ii) Power unit consumed in an hour and for 1000 ltr of water evaporation as well as (iii) Operating cost for an hour and for 1000 ltr of water evaporation were estimated at varying pressure in pump. Besides this, the comparative study of batch and continuous operation was conducted. The results show that this newer approach may genuinely and techno-economically ensure ‘Zero Discharge’.