Exhausted Fungal Biomass as a Feedstock for Increasing Methane Production During the Anaerobic Digestion of Organic Wastes

Abstract

Biochemical methane potential tests of exhausted fungal biomass were assessed in batch assays at mesophilic temperature to study the feasibility of an anaerobic digestion treatment to valorize this substrate. The inocula used were collected from two different sources: the anaerobic digester of a wastewater treatment plant (WWTP) and an anaerobic reactor treating the organic fraction of municipal solid waste (OFMSW). The results showed higher methane yields when using the WWTP inocula (595 mL CH4/g VSfeed) compared with the inocula obtained from the digester treating OFMSW (281 mL CH4/g VSfeed). Further experiments evaluated biogas production of fungal biomass when β-estradiol (E2) and 17α-ethinylestradiol (EE2) were spiked onto the substrate at a concentration of 2 mg/L respectively. No differences in methane yield were detected at the end of the experiments for spiked and non-spiked biomass (367 and 307 mL CH4/g VSfeed, respectively), confirming no toxic effect of the hormones at the concentration tested. This study confirms the feasibility of anaerobic digestion treatment for the valorization of fungal substrate containing these emerging pollutants.