Biogas generation by hybrid treatment of dairy wastewater with lipolytic whole cell preparations and anaerobic sludge

Abstract

This study aimed to assess the potential of the biochemical methane production and biodegradability of dairy wastewater employing a hybrid treatment: granular anaerobic sludge as inoculum and whole cells of Penicillium citrinum with high lipase activity. It was expected that mycelium-bound lipase from whole cells would enhance hydrolysis, contributing to the efficiency of anaerobic digestion by granular inoculum. Seven substrate and microbial combinations were prepared; five contained the inoculum and whole cells cultivated in different agroindustrial wastes and two were controls (inoculated and uninoculated). A synergistic microbial interaction was evidenced by the high cumulative methane production after 45 h of reaction, reaching 231 mL g−1 volatile solids. pH was maintained at values near neutrality in all treatments, and chemical oxygen demand removal ranged from 42 to 57 % in hybrid treatments. First-order and modified Gompertz kinetic models were fitted to experimental data, and a lag phase was not observed. The results show the potential of hybrid treatment of dairy wastewater with whole cells produced in waste-based media for biogas production.