Simultaneous domestic wastewater and nitrate sewage treatment by DEnitrifying AMmonium OXidation (DEAMOX) in sequencing batch reactor

Abstract

A novel DEAMOX system was developed for nitrogen removal from domestic wastewater and nitrate (NO3−-N) sewage in sequencing batch reactor (SBR). High nitrite (NO2−-N) was produced from NO3−-N reduction in partial-denitrification process, which served as electron acceptor for anammox and was removed with ammonia (NH4+-N) in domestic wastewater simultaneously. A 500-days operation demonstrated that the efficient and stable nitrogen removal performance could be achieved by DEAMOX. The total nitrogen (TN) removal efficiency was as high as 95.8% with influent NH4+-N of 63.58 mg L−1 and NO3−-N of 69.24 mg L−1. The maximum NH4+-N removal efficiency reached up to 94.7%, corresponding to the NO3−-N removal efficiency of 97.8%. The biomass of partial-denitrification and anammox bacteria was observed to be wall-growth. The deteriorated nitrogen removal performance occurred due to excess denitrifying microbial growth in the outer layer of sludge consortium, which prevented the substrate transfer for anammox inside. However, an excellent nitrogen removal could be guaranteed by scrapping the superficial denitrifying biomass at regular intervals. Furthermore, the high-throughput sequencing analysis revealed that the Thauera genera (26.33%) was possibly responsible for the high NO2−-N accumulation in partial-denitrification and Candidatus Brocadia (1.7%) was the major anammox species.