Enhanced Biogas Production through Anaerobic co-Digestion of OFMSW with Maize Cob Waste Pre-Treated with Hydrogen Peroxide

Abstract

The enhancement of biogas and CH4 yields through anaerobic co-digestion (co-AD) of the pre-hydrolysed Organic Fraction of Municipal Solid Waste (hOFMSW) and Maize Cob Waste (MCW) was tested in a lab- scale thermophilic anaerobic reactor. Before the co-AD, MCW was chemically pre-treated with H2O2 at room temperature in alkaline conditions (10 % MCW wMCW/ valkaline water) with 4 hours contact time, at a ratio of 0.5 wH2O2/wMCW. This pre-treatment is the last of a set of pre-treatments catalysed by H2O2 already tested by the authors. The anaerobic reactor was initially fed with hOFMSW obtained from the hydrolysis tank of an industrial AD plant. The hOFMSW was co-digested with the pre-treated MCW and then with non-pre-treated MCW. The co-AD of hOFMSW with pre-treated MCW (CASE 1) increased the biogas yield by 65 % and CH4 yield by 48 %, when compared to the results obtained with the standalone hOFMSW, while the co-digestion of hOFMSW with non-pre-treated MCW (CASE 2) increased biogas and CH4 yields by 84 % and 57 %, respectively. Despite of higher yields, the Low Heating value (LHV) and daily energy content (LHV * Volume of biogas per day) in biogas stream, obtained in CASE 2 were on average 4 % and 1% lower, respectively than in the biogas stream obtained with CASE 1. These results showed that the pre-treatment is recommended before submitting MCW to co-AD and the chemical pre-treatment of MCW with H2O2, at room temperature, is a promising low-cost way to valorise MCW through co-AD.