SUMMARY
Recently, more decentralized wastewater treatments are of great interest for rural regions. In this work, a novel ANF-WDSRBC system combined with an anoxic filter (ANF) and a four-stage water-dropping-self-rotating biological contactor (WDSRBC) was designed as a post-treatment option. With a total hydraulic retention time (HRT) of 8.8 h and reflux ratio of 1:1, the ANF-WDSRBC system was operated 160 days. The results showed the ANF-WDSRBC system had better performance without mechanical aeration devices, the removal efficiencies of chemical oxygen demand (COD), ammonia (NH4+–N) and total nitrogen (TN) were 61.4% ± 4.3%, 86.1% ± 3.7%, and 54.5% ± 3.9%, respectively. By means of high-throughput MiSeq sequencing, the results suggested that Proteobacteria, Bacteroidetes, Firmicutes, and Chloroflexi were the predominant phyla in the system. In the WDSRBC units, Nitrosomonas, Nitrosospira, Bacillus, and Nitrospira were the main genera to take part in nitrification. Longilinea, Bellilinea, Thiobacillus, and Thauera in the ANF unit were the main genera to participate in denitrification and organic matters degradation. The novel ANF-WDSRBC system had great potential in the post-treatment of decentralized domestic wastewater.