Ratio Optimization for Biogas Production from Agricultural Waste Co-Digested with Sewage Sludge

Samyuktha S , Latha K, Sivanesan S

Abstract

This paper describes the anaerobic biochemical methane potential (BMP) of  agricultural waste, co-digested with sewage treatment plant (STP) sludge  as  an alternative renewable energy source coupled with an efficient waste management solutions.  The anaerobic co-digestion mixing ratio of agricultural waste, with STP sludge and anaerobic seed sudge was optimized to maximize the biogas and methane yield and to minimize the ammonia toxicity in methanogenesis process. The ratios (agricultural waste, STP sludge and seed sludge) used were 1:2:1, 2:1:1, 3:1:1 and 1:3:1. The optimization of different ratios and the impact of Chemical Oxygen Demand (COD), Volatile Fatty Acids (VFA), Ammonia and Alkalinity on biogas production were monitored using BMP bottling method. The ratio 1:2:1 was found to have good biogas production with maximum of 489 ml/day with subsequent changes in process monitoring parameters. This will help to design the large scale plant with respect to the waste handled in the anaerobic digestion process.