Effect of chemical composition on the anaerobic co-digestion of source segregated organic fraction of municipal solid wastes

Abstract

Recently waste to energy projects gaining more attraction due to rapid waste generation due to increased urbanization. Improper municipal solid waste (MSW) treatment resulting in environmental risks such as air pollution, ground, and surface water contamination. Anaerobic digestion (AD) is the best method to treat organic solid waste. Mono-AD of organic fraction of municipal solid wastes (OFMSW) leads to lower methane yield due to the accumulation of volatile fatty acids (VFAs). Mixing of two or more substrates (Co-digestion) dilutes the toxic compounds and increases the methane yield by providing proper environment for microbes. In this study anaerobic co-digestion (AcoD) of source segregated OFMSW (particularly food waste, fruit waste, and vegetable waste) with chicken fecal matter (co-substrate), and cow dung (inoculum) was investigated by using batch studies (Duration of 30 days). AcoD carried out in three different batch reactors viz. R1 (food mix), R2 (vegetable mix), and R3 (fruit mix) feed with substrates (S1& S2) and inoculum (I) (S1: S2: I = 0.5:0.5:2). The methane percentage obtained for reactor R1 was 69.60%, which is higher compared to the other reactors (R2- 61.2%, and R3- 57.37%). R1 reactor had higher methane yield due to its higher lipids (higher VFAs), and proteins (sufficient buffer capacity). R3 reactor had lowest methane yield due to its highest carbohydrates (rapid acidification), and lower proteins (lower buffer capacity). Modified Gompertz model gave better results near to experimental studies. The present study proved that mixing OFMSW with proper co-substrate (protein-rich) increases the methane yield by providing proper buffer capacity.