Bacterial community composition in a two-stage anaerobic membrane bioreactor for co-digestion of food waste and food court wastewater

[Display omitted] •The particle mean size was one of the factors influencing the HR performance.•Predominant genera were Lactobacillus in the HR and Methanobacterium in the UASB.•Anaerobic co-digestion favored hydrogenotrophic over acetoclastic methanogenesis.•The UASB showed better metabolism pathway diversity and dispersion than the HR. This study investigated the microbial community of a two-stage anaerobic membrane bioreactor (2S-AnMBR) co-digesting food waste and food court wastewater. The hydrolysis reactor (HR) was dominated by Bacteroidetes and Firmicutes phylum, with genus Lactobacillus enriched due to food waste fermentation. The up-flow anaerobic sludge blanket (UASB) was dominated by genus such as Methanobacterium and Methanosaeta. The presence of Methanobacterium (91 %) and Methanosaeta (7.5 %) suggested that methane production pathways inevitably undergo both hydrogenotrophic and acetoclastic methanogenesis. Hydrogen generated during hydrolysis fermentation in the HR contributed to methane production in the UASB via hydrogenotrophic pathways. However, the low abundance of Methanosaeta in the UASB can be attributed to the limited inffluent of volatile fatty acids (VFA) and the competitive presence of acetate-consuming bacteria Acinetobacter. The UASB exhibited more excellent dispersion and diversity of metabolic pathways compared to the HR, indicating efficient methane production.