Comprehensive analysis of the microbial communities and operational parameters of two full-scale anaerobic digestion plants treating food waste in South Korea: Seasonal variation and effect of ammonia.

There are about ninety full-scale anaerobic digestion (AD) plants in South Korea that treat food waste (FW); however, the key diff ;erences in the microbial communities in different seasons and the effects of ammonia in AD remain poorly understood. In this study, the seasonal changes in microbial communities associated with operational parameters of two full-scale ADs (C and W plants) treating FW were analyzed. The organic loading rate (OLR) variability had an influence on the seasonal CH4 yield; the W plant had a lower CH4 yield with an unstable AD performance while the C plant had a higher CH4 yield with a stable AD performance. It was mainly due to the substantially different NH4+ concentration; the W plant had a NH4+ concentration nearly 1.6 times higher compared to the C plant. The high NH4+ presence in the W plant led to the dominance of class Clostridia, and methanogenesis was mostly done by hydrogenotrophs (Methanomassiliicoccus luminyensis). Additionally, the members belonging to Clostridia and Bacteroidia were found at both plants in each season (share ≥0.5%) implying their indispensable role during the anaerobic digestion of FW.