Effect of initial pH on biodegradation of distillery wastewater by batch process using anaerobic mixed consortia

Biodegradation of distillery wastewater is dependent on initial pH. In this present research, the effect of initial pH from 5.0 to 6.5 on biodegradation of distillery wastewater using anaerobic mixed consortia by batch process was investigated. The parameters like chemical oxygen demand (COD) removal efficiency, oxidation reduction potential (ORP), final pH, total phenol content, total protein were determined to study the biodegradation of distillery wastewater. From the experimental results, maximum COD removal efficiency of 91.96 % was obtained an initial pH 6.0. Maximum phenol removal, protein removal and decolourization percentage recorded were 88.76%, 71.04% and 55.23% respectively at initial pH 6.5. It could be concluded that initial pH 6.5 are favourable for maximum biodegradation of distillery wastewater. Introduction Molasses-based distilleries generate around 8–15 L of wastewater with high chemical oxygen demand (COD) (80–160 g/L) for every litre of the alcohol produced 1 . It ranks high amongst the pollutants produced by industries and its treatment had been a challenge for a long time. It contains high concentration of biodegradable organic material, such as sugars, lignin, hemicelluloses, dextrin, resins and organic acids 2 . The high COD, nitrogen and phosphates content contribute to eutrophication of lakes and rivers 3 . The brown colour of the distillery wastewater is due to the water soluble recalcitrant colouring compound called melanoidin that are formed during Maillard reaction between a sugar and amino acid 2,4 . They are acidic, polymeric with highly dispersed colloid and are negatively charged due to the dissociation of carboxylic acids and phenolic groups. They possess antioxidant properties, which are toxic to aquatic organisms 5 . Biological (both aerobic and anaerobic treatment), activated sludge treatment, clarification, physic-chemical treatment and filtration are some of the treatment technologies being carried out. Anaerobic treatment of spent wash ensures high degree of treatment and also recovery of renewable resources, which serves as dual purpose 4 . Anaerobic digestion is more attractive for tropical countries like India, where temperatures are suitable for anaerobic digestion 6,7,4. Suitable microbes are available for biodegradation of distillery wastewater. Application of bacteria, yeast, fungi, etc used for the biodegradation of distillery effluent 1,3,8 . Besides, anaerobic mixed consortia can also be used for biodegradation which can degrade the pollutants. In this research work, the effect of initial pH on biodegradation of distillery wastewater was investigated.