Effect of direct enzyme addition on the anaerobic digestion of OFMSW

The organic fraction of municipal solid waste (OFMSW) has high biodegradability and is a good feedstock for anaerobic digestion (AD). However, the solubilization of OFMSW is a limiting factor for AD. In this study, enzyme treatment was investigated to increase the conversion of complex materials of OFMSW into soluble fractions. Six different concentrations (0.15, 0.3, 0.5, 1.0, 1.5 and 3.0 mg/VSadded) of the alpha amylase enzyme (obtained from Aspergillus oryzae) were directly added as a powder and automated biochemical methane potential (BMP) tests were performed under thermophilic conditions. According to BMP tests, the methane (CH4) yield increased up to 17.5 % and the lag phase decreased to 19.3 % after enzyme addition. The highest CH4 yield and shortest lag phase were obtained when 0.5 mg of enzyme/VSadded was added to the reactor. These findings suggest that direct alpha amylase enzyme application obtained from Aspergillus oryzae can be used to increase biogas production by enhancing solubilization of OFMSW for AD. [Display omitted] •The impact of direct alpha amylase enzyme addition on OFMSW was investigated.•The addition of enzyme reduced the lag phase by up to 19.3 %.•The cumulative methane yield was increased by 17.5 % via direct enzyme dose.•The optimal enzyme dose was determined to be as 0.5 mg/VSadded.