A snapshot of microbial community structures in 20 different field-scale anaerobic bioreactors treating food waste

Abstract

This study aimed to identify significant factors shaping the microbial populations in biogas plants treating food waste (FW). Twenty full-scale anaerobic acidogenic/methanogenic bioreactors, located at 11 FW treatment facilities, were compared to find patterns in their microbial community structures and potential interactions with the process parameters. Temperature, hydraulic retention time, and organic loading rate were design parameters that systematically influenced the microbial communities. The latter two clearly separated the acidogenic and methanogenic bioreactors. Lactobacillus was the dominant (69.7 +/- 19.8%) bacteria in the acidogenic reactors, while hydrogen-utilizing methanogens, such as Methanoculleus (65.1 +/- 33.5%), were the dominant archaea in most methanogenic digesters. Defluiviitoga was the dominant (82.7 +/- 1.4%) bacteria in the thermophilic digesters, but was also the most abundant (33.1-33.6%) bacteria in dry mesophilic digesters. The two bioreactor categories had lower bacterial diversities, and also higher propionate concentrations (> 5 g/L in 4 out of 5 cases), which may impose potential risks for the management of such digesters. The current 'snapshot' of the microbial communities suggests several bacterial and archaeal taxa as potential indicators of bioreactor categories and/or process variables.