Biomethane recovery performance and microbial community dynamics of a high-biomass submerged AnMBR (HBSAnMBR) treating abattoir wastewater

This study investigated the treatment and biomethane recovery performance of a high-biomass submerged anaerobic membrane bioreactor (HBSAnMBR) treating abattoir wastewater in six operational phases (Phases 1 – 6) at an organic loading rate (OLR) range of 1.05 – 7 kg-COD/m3/d. The HBSAnMBR system demonstrated a biomethane recovery of 75.5 ± 2.0% and COD removal efficiency of 98.8 ± 0.71% during the most sustainable operational phase at an OLR of 4 kg-COD/m3/d. Volatile fatty acids (VFAs) such as acetic, propanoic, isobutyric, and valeric acids significantly correlated with OLR and biomethane production, while butyric and isovaleric acid concentrations were unaffected. The biomethane recovery performance of the HBSAnMBR system correlated positively with microbial community dynamics in different operational phases. The functional analysis of the microbiome indicated that Pseudomonas and Anaerolineaceae played a significant role in the hydrolysis and fermentation of complex organic matter, which led to the production of VFAs and other intermediate products. Methanothrix were observed to utilize acetate for acetoclastic methanogenesis at OLR 4 kg-COD/m3/d, producing the highest biomethane. On the contrary, the acetoclastic methanogenesis was replaced by hydrogenotrophic methanogenesis by Methanolinea and Methanospirillum at OLR above OLR 4 kg-COD/m3/d, leading to a decline in biomethane production.