Enhanced biological nitrogen removal from sediment by graphene derivative-mediated community assembly.

Understanding the underlying mechanism that drives the microbial community mediated by graphene derivative is crucial for achieving the enhancement of biological nitrogen removal by external stimulation. The main objectives of this study were to identify the bacterial community assembly mechanism via null model test and molecular ecological network analysis in the sediment culture system. Results showed graphene derivative increased biological nitrogen removal efficiency by 125%. The high electron transfer efficiency and denitrifying enzyme activities were achieved. Deterministic assembly is dominate (>90%) in all the community assembly while the stochastic assembly process only existed in graphene derivative system (6.67%). The nitrogen removal was enhanced due to the intensification of the interaction on the microbial community between stochastic assembly and deterministic assembly. Keystone taxa in the graphene derivative systems, including Sulfuricella, Rhodobacter, and Comamonadaceae, drove the alteration of community structure relating to the nitrogen removal.