The anaerobic digestion microbiome is robust toward variation in the waste activated sludge feed.

Anaerobic digestion stands out as the foremost technology for maximizing the valorization of waste activated sludge (WAS) to recover energy and recover resources. The physical/chemical and microbial makeup of WAS is susceptible to seasonal fluctuations, due to the open-air nature of wastewater treatment facilities, potentially impacting subsequent digester performance and the quality of the resulting digestate. This study delved into a comprehensive analysis of both the initial WAS and the digestate produced by 12 full-scale digesters during both a summer and winter sampling campaign. A significant influence of seasonal variations was observed on the physical/chemical and microbial composition of WAS. Interestingly, the digestate microbiome exhibited a high resilience with minimal seasonal fluctuations, but instead showed variations between different digesters. In summary, this research demonstrates that while WAS composition manifests in specific physical/chemical attributes, it does not exert a discernible influence on the microbial composition of the resulting digestate.