TREATMENT OF TEXTILE WASTE USING FeC13 COAGULANT

Abstract

Pollution problems caused by the textile mill waste water has been one of the most crucial and common problems of environmental Engineering. The most noticeable characteristic of the effluents from such industries is colour. Colours not only casuse the aesthetically unpleasant effects but also reduce the self-purification capacity of natural streams by inhibiting photo synthetic production of oxygen and direct destruction of aquatic communities. COD and total solids are also discharged from these industries with high concentration. Phyisco-chemical treatments of such waste waters are still finding wider applications because of its better efficiency and ease in operation, although new researches are being done on biological treatment of textile mill waste waters. The present work addresses to the treatment of such wastes by coagulation process. The combined waste water from a textile mill has been studied to determine the effectiveness of ferric chloride and lime and their combinations. It was found that the use of ferric chloride and lime together produced results that were far superior to those achieved with ferric chloride alone or with lime alone as far as the cost and percentage removal of pollution parameters (colour, COD, TDS and total solids) is concerned. For the textile mill waste water, the performance of commercial ferric chloride went on improving as the pH of sample was increased. At pH 12.0, the removal of colour, COD, TDS and total solids was found to be 92.7%, 72.3% 64.7% and 67.1% respectively with a ferric chloride dose of 80 mg/1 of waste water. From economical point of view, the best Results were obtained by the coagulation of waste water with lime and 20 mg/1 of ferric chloride. The colour, COD, TDS and total solids removal was found to be maximum (95.4%, 68.3%, 67.2% and 60.9% respectively) at cost of treatment of Rs. 6300. per MLD whereas the chemical cost of waste water treatment at pH of 12.0 is Rs. 7200 per million litres of waste water. (