Changes in bacterial diversity of full-scale anaerobic digesters treating secondary sludge

Anaerobic digestion (AD) of secondary sludge (2S) presents challenges because of its high microbial content and complex cell wall structures. The purpose of this study was to investigate the effects of spatiotemporally-variable factors such as water temperature and dietary habits on the 2S bacterial community and its migration into digesters. Bacterial communities and functions were analyzed using high-throughput pyrosequencing. Spatiotemporal variations in bacterial populations were identified, with genera such as Zoogloea and Dechloromonas migrating into digesters and influencing organic degradation. Notably, Zoogloea was negatively correlated with VS removal, potentially due to cell floc formation, whereas Dechloromonas was positively correlated, suggesting its role in acetate metabolism anaerobically. This study emphasizes the importance of microbial migration from 2S to digesters, highlighting the need to monitor microbial communities along with conventional parameters to increase AD performance. These findings provide practical insights into optimizing sludge management and improving biogas production in AD plants.