Coproduction of hydrogen, butanol, butanediol, ethanol, and biogas from the organic fraction of municipal solid waste using bacterial cocultivation followed by anaerobic digestion

An integrated bioprocessing approach was applied to enhance energy recovery from the biodegradable fraction of municipal solid waste (BFMSW). Clostridium acetobutylicum and Enterobacter aerogenes with complementary characteristics were cocultivated for coproduction of hydrogen, 2,3-butanediol, and acetone-butanol-ethanol (ABE). Following the fermentation process, the remaining solids were used for biomethane production. The BFMSW was first subjected to ethanolic organosolv pretreatment and then enzymatic cellulose and hemicellulose hydrolysis at 5 and 8% solid loadings. The glucose (328 g/kg _{raw BFMSW}), xylose (37.8 g/kg _{raw BFMSW}), and starch (152.1 g/kg _{raw BFMSW}) portions of the pretreated BFMSW hydrolysate with 5% solid loading were cofermented to hydrogen (162.8 L/kg _{raw BFMSW}), 2,3-butanediol (42.5 g/kg _{raw BFMSW}), butanol (121.9 g/kg _{raw BFMSW}), ethanol (38.9 g/kg _{raw BFMSW}), and acetone (45.2 g/kg _{raw BFMSW}) by the coculture, and subsequently, the residual unfermented solids were further digested to biomethane (31.7 L/kg _{raw BFMSW}). From the bioenergy perspective, 311.8 mL gasoline equivalent (10 MJ energy) was obtained from each kg of raw BFMSW, indicating the potential of the integrated fermentation-anaerobic digestion bioprocess for biofuels production from the zero-cost substrate.