Pollutants degradation performance and microbial response evaluation about expressway service area sewage treatment of continuous flow AO-MBBR system in the start-up period

The treatment of expressway service area sewage (ESAS) confronts great challenges owing to its unique characteristics of high ammonia nitrogen (NH4+-N) concentrations and low carbon/nitrogen (C/N) ratio. In order to address the issue, an anoxic-oxic moving bed biofilm reactor (AO-MBBR) system was continuously started up for 60 days to explore the potential influence of hydraulic retention time (HRT) on the contaminant removal for ESAS in this study. The HRT had no striking influence on organic degradation performance, the total nitrogen (TN) removal efficiency was increased by 17.73% accompanied by extending HRT. The denitrifiers Thiothrix and Trichococcus were dominant genus when HRT were 13.5h and 18h respectively. The neutral community model showed that the stochastic processes was crucial in shaping the assembly of microbial communities during the operation. Besides, a closer collaborative relationship between key genus was built as HRT increased, which ensured the stable pollutant removal efficiency of the system. Overall, this work provided a new idea and illustrated the intrinsic role of HRT for the ESAS treatment.