Sustainable biofuels and bioplastic production from the organic fraction of municipal solid waste

Abstract

Municipal solid waste is an environmental threat worldwide; however, the organic fraction of municipal solid waste (OF-MSW) has a great potential for the generation of fuels and high-value products. In the current study, OF-MSW was utilized for the production of ethanol, hydrogen, as well as 2,3-butanediol, an octane booster, by using Enterobacter aerogenes. Furthermore, a promising alternative to non-biodegradable petrochemical-based polymers, polyhydroxyalkanoates (PHAs), was produced. The OF-MSW was first pretreated by an acetic acid catalyzed ethanol organosolv pretreatment at 120 and 160 °C followed by enzymatic hydrolysis of the residual solids. The residual unhydrolyzed solids resulting from enzymatic hydrolysis were further anaerobically digested for methane production. The enzymatic hydrolysis of the solids prepared at 120 °C for 60 min led to the production of hydrolysate with the highest glucose production yield of 498.5 g/kg dry untreated OF-MSW, which was fermented to 139.1 g 2,3-butanediol, 98.3 g ethanol, 28.6 g acetic acid, 71.4 L biohydrogen, and 40 g PHAs. Moreover, 23.1 L biomethane was produced through the anaerobic digestion of the enzymatic hydrolysis residue solids. Thus, appreciable amounts of energy (8236.9 kJ) and an eco-friendly bioplastic were produced by the valorization of carbon sources available in OF-MSW.

Keywords: 2,3-Butanediol; Biohydrogen; Enterobacter aerogenes; Ethanol; Polyhydroxyalkanoates.