Enhanced nitrogen removal and microbial community of the mainstream deammonification treating fluctuating influent C/N wastewater by the novel functional carriers

The plug-flow fixed bed reactors with zeolite/tourmaline-modified polyurethane carriers (PFBR_ZTP) and polyurethane carriers (PFBR_PU) were operated to assess the fluctuating influent C/N impact on the system performance and the carrier effect on the enhancing the system operation. Result suggested that fluctuations in influent C/N and variations in operational temperature reduced the removal performance and system stability within PFBR_PU. The negative impact of C/N fluctuation could be effectively mitigated by effluent reflux. In contrast, PFBR_ZTP performance and operational stability of maintained at high level with a greater nitrogen removal rate (0.18 kg N·(m³·d)^-1). Redundancy analyses showed that the fluctuations in influent C/N dramatically affected the microbiome structure in PFBR_PU, and the leading influencing factor was shifted to the fluctuating amount of influent C/N, which in turn reduced the system performance and stability. ZTP carriers could maintain the balance of main functional bacterial activity and abundance and promote the partial denitrification process with a higher Thauera abundance of 0.48%.