Analysis on biodegradation and colour reduction of distillery effluent spent wash

The disposal of large quantities of biodegradable waste without adequate treatment results in significant environmental pollution. The distillery effluent which is also known as spent wash is discharged as a waste from distilleries. This is the major source of aquatic and soil pollution because intense brown colour which results in the blockage of photosynthesis, eutrophication and low pH acidifies soil affecting agricultural crops. It is one of the most complex and cumbersome waste having very high BOD and COD content, highly acidic pH, with other organic and inorganic toxic constituents. Anaerobic digestion of biodegradable waste results in both energy generation and reduction of greenhouse gas emissions. The main objective of this project was to treat the spent wash by anaerobic digestion using methanogenic bacteria and reduction of colour, sulphate by the bacterium. Anaerobic digestion results in 69.09 % reduction in COD and the pH changes to acceptable level. In the present study, efficient degradation of sulphate and colour reduction of raw effluent spent wash was achieved using Pseudomonas aeruginosa (MTCC 2474). The organism exhibited 72.03 % of sulphate reduction, 47.6 % colour reduction and 76.62 % of COD reduction. Further the study revealed that sulphate is converted into hydrogen sulphide during microbial treatment of distillery effluent and the presence of excess sulphate was found inhibitory for degradation of distillery effluent and bio methanogenesis.