Biogas production from anaerobic co-digestion of sewage sludge and food waste in continuously stirred tank reactor

The purpose of current investigation was to explore the scope of integrating an anaerobic digester in a decentralized municipal wastewater treatment plant for in-situ treatment of household waste. The present work intends to identify the potential of sewage sludge and food waste for biogas generation. The study was conducted in lab scale continuous stirred tank reactor having a working volume of 6.5 L at mesophilic temperature. The paper mill sludge was used as inoculum and was stabilised using food waste substrate for initial 50 days in batch mode. Co-digestion of food waste (FW) and bio-flocculated sewage sludge (BFS) was performed using continuous feeding for maintaining OLR of 2.5 gVSL- 1D- 1at HRT of 4 days for 120 days. 2% FW and 98% BFS (by volume) was feeded in the reactor throughout the experimental duration. The highest VFA accumulation of 1902 mg L-1 were observed and maximum bio-methane yield was found to be 127.05 mLCH4 g- 1 VSadded. The pH with current feeding ratio was found stable during the reactor operation without adding external alkalinity source.