Performance and microbial community analysis of a novel DEAMOX based on partial-denitrification and anammox treating ammonia and nitrate wastewaters

In this study, a novel DEAMOX (DEnitrifying AMmonium OXidation) process coupling anammox with partial-denitrification generated nitrite (NO2--N) from nitrate (NO3--N) was developed for simultaneously treating ammonia (NH4+-N) and NO3--N containing wastewaters. The performance was evaluated in sequencing batch reactors (SBRs) with different carbon sources for partial-denitrification: acetate (R1) and ethanol (R2). Long-term operation (180 days) suggested that desirable nitrogen removal was achieved in both reactors. The performance maintained stably in R1 despite the seasonal decrease of temperature (29.2 degrees C-12.7 degrees C), and high nitrogen removal efficiency (NRE) of 93.6% on average was obtained with influent NO3--N to NH4+-N ratio (NO3--N/NH4+-N) of 1.0. The anammox process contributed above 95% to total nitrogen (TN) removal in R1 with the nitrate-to-nitrite transformation ratio (NTR) of 95.8% in partial-denitrification. A little lower NRE was observed in R2 with temperature dropped from 90.0% at 22.7 degrees C to 85.2% at 16.6 degrees C due to the reduced NTR (87.0%-67.0%). High-throughput sequencing analysis revealed that Thauera genera were dominant in both SBRs (accounted for 61.53% in R1 and 45.17% in R2) and possibly played a key role for partial-denitrification with high NO2--N accumulation. The Denitratisoma capable of complete denitrification (NO3--N -> N-2) was found in R2 that might lead to lower NTR. Furthermore, different anammox species was detected with Candidatus Brocadia and Candidatus Kuenerda in R1, and only Candidatus Kuenenia in R2. (C) 2016 Elsevier Ltd. All rights reserved.