Treatment performance and mechanism of source-separated blackwater using an earthworm-based reactor for rural applications.

-N. Microbial community analysis revealed significant enrichment of genera such as Ferruginibacter, Lysobacter, the JG30-KF-CM45 group, members of family Isosphaeraceae and Chitinophagaceae in ER. These genera exhibited positive correlations with COD and nitrogen removal, suggesting their potential roles in carbon and nitrogen transformation. The enrichment of autotrophic and heterotrophic nitrifying bacteria in the ER was associated with enhanced nitrogen transformation, and FAPROTAX predictions supported increased denitrification potential. Collectively, these correlative data suggest that Eisenia fetida may enhance carbohydrate and nitrogen metabolism. However, this system did not significantly improve phosphorus removal; therefore, the effluent requires appropriate treatment based on its intended application. This study provides a theoretical basis for earthworm-based reactors in treating rural blackwater.