Assessment of microbial consortiums and their metabolic patterns during the bioconversion of food waste

Anaerobic digestion (AD) of food waste (FW) is a complex process that involves a four-stage sequential bioconversion of organic matter into biogas, catalyzed by a group of microorganisms at every stage. The efficiency depends on the diversity of microbial consortiums used as inoculum. The present study aimed to understand the influence of microbial diversity and their metabolisms during the anaerobic digestion of food waste. For which, three different mixed consortiums were considered: cow dung (R-1), sewage sludge (R-2), and a mixture of cow dung and sewage sludge (R-3). It was observed that the mixed consortia (R-3) produced maximum biogas (310 mL) along with remarkable volatile fatty acids (VFA, 2445 mg/L) due to a higher soluble chemical oxygen demand (sCOD) R-3 (62%), R-2 (61%), and R-1 (54%), as well as efficient removal of sCOD in R-3 (66%), R-1 (34%), and R-2 (32%). Furthermore, different organic loads were assessed, of which 5 g TS/L and 10 g TS/L showed good biogas production along with a notable amount of VFA. Metagenomics analysis of R-3 showed better microbial diversity as compared to individual ones (R-1 and R-2), and the experimental results were corroborated with the potential metabolic mechanisms involved in the AD of FW process, which were also proposed.