Partial nitrification coupled with anammox in a biofilter reactor (BR) of large height-to-diameter ratio for treatment of wastewater with low C/N

Abstract

A biofilter reactor (BR) with large height-to-diameter ratio was developed for the continuous treatment of wastewater with high ammonia nitrogen and low carbon in this study. The BR integrated carbon oxidation, partial nitrification, and anammox process in a single-stage reactor and acquired an average removal rates of 91.9 % for NH4+-N and 82.5 % for TN when the nitrogen loading rate (NLR) reached 2.0 kg/(m3·d)) with the ammonia nitrogen of 800.0 ± 2.0 mg/L in the influent. The results revealed that nearly half of NH4+-N was stably converted into NO2−-N at the zone height of 0–40 cm in the reactor, which provided suitable conditions for the subsequent anammox process at the height of 80–160 cm. Meanwhile, high-throughput sequencing results further revealed that aerobic autotrophic bacteria were the main kind of bacteria at the zone height of 0–40 cm, whereas Candidatus_Brocadia were the main bacteria at the height of 80–160 cm. Thus, a BR with a large height-to-diameter ratio can combine the partial nitrification and anammox (PN/A) process in a single reactor, providing an effective technology for the treatment of high-ammonia-nitrogen wastewater.