STUDIES ON POLISHING OF DISTILLERY EFFLUENT

Abstract

Distilleries are amongst one of the gross water polluting industries identified by Pollution Control Boards with about 80% of the raw material ending up as waste. Sugar cane molasses is generally the raw material used in the production of alcohol. As a general rule the waste has BOD in the range of 45,000 to 60,000 mg/1 and COD in the range of 1,00,000 mg/1 to 1,30,000 mg/l. According to IS:2490 and IS:7968 the BOD for disposal in river and Land are 30mg/1 and 100mg/1 respectively. Several studies under taken by investigators in this field have failed to suggest a method or combination in tackling this problem and to reduce the pollution load to desirable standards. The effluent of such treatment units have BOD, COD, S.S. far in excess of permissible standards. Caramel colour also poses a problem. In this study an attempt has been made to further improve the quality of treated distillery effluent, so that it may come with in permissible standards for safe. disposal. Several options were tried, to grow yeast on the residual carbonaceous matter present in the waste by adding nutrients, but it did not gave encouraging results. Physico-chemical methods were thus the only possible means left for polishing. Coagulation using various coagulants such as lime, alum, bleaching powder, lime & alum, alum with poly acrylamide were tried and results presented here in. Encouraging results by using alum with coagulant aid were obtained with reduction of COD upto 62%, BOD upto 83%, S.S. upto 86% & colour upto 94% .