Obtaining green energy from dry-thermophilic anaerobic co-digestion of municipal solid waste and biodiesel waste

This study has been conducted to optimise the dry-thermophilic anaerobic co-digestion of two different types of real waste (municipal solid waste and biodiesel waste) in a semi-continuous feeding regime, under high organic loading rates (OLRs) or low hydraulic retention times (HRTs). For this purpose, different high OLRs (from 10 to 34 g [VS] l−1 d−1) or low HRTs (from 10 to 4.4 d) were investigated in a continuously stirred tank reactor. Optimal conditions (257 ml [CH4] g−1 VS; 6.03 ± 0.43 l [CH4] l−1 d−1; 16.3 ± 2.3 × 10−12 l [CH4] cell−1 d−1) were obtained at 4.4 d HRT (OLR = 23 g [VS] l−1 d−1), in which the average values of the ratios of Eubacteria:Archaea and hydrolytic-acidogenic bacteria:acetogens were 95:5 and 87:8, respectively.