Achieving simultaneous removal of carbon and nitrogen by an integrated process of anaerobic membrane bioreactor and flow-through biofilm reactor

In this study,a combined system consisting of an anaerobic membrane bioreactor(AnMBR)and flow-through biofilm reactor/CANON(FTBR/CANON)was developed to simultaneously remove carbon and nitrogen from synthetic livestock wastewater.The average removal efficiencies of total nitrogen(TN)were 64.2 and 76.4%with influent ammonium(NH4+-N)concentrations of approximately 200 and 500 mg/L,respectively.The COD removal efficiencies were higher than 98.0%during the entire operation.Mass balance analysis showed that COD and TN were mainly removed by the AnMBR and FTBR/CANON,respectively.The anammox process was the main nitrogen removal pathway in the combined system,with a contribution of over 80%.High functional bacterial activity was observed in the combined system.Particularly,an increase in the NH4+-N concentration considerably improved the anammox activity of the biofilm in the FTBR/CANON.16S rRNA high-throughput sequencing revealed that Methanosaeta,Candidatus Methanofastidiosum,and Methanobacterium were the dominant methanogens in the AnMBR granular sludge.In the CANON biofilm,Nitrosomonas and Candidatus Kuenenia were identified as aerobic and anaerobic ammonium-oxidizing bacteria,respectively.In summary,this study proposes a combined AnMBR and FTBR/CANON process targeting COD and nitrogen removal,and provides a potential alternative for treating high-strength wastewater.