Nitrogen Removal Performance And Microbial Community Structure Analysis Of MAB Under Nitrogen Shock Loadings

Marine anammox bacteria play an important role on marine nitrogen cycle.MAB are applied to treat nitrogen-rich saline wastewater under low-temperature conditions for its peculiarity on high salinity and low temperature tolerance.In this work,MAB were successfully enriched by inoculating intertidal sediments from Jiaozhou Bay.The nitrogen removal performance of MAB treating nitrogen-rich saline wastewater under nitrogen shock loadings was analyzed,as well as the effect of Fe???on MAB under nitrogen shock loadings.MAB were successfully enriched by inoculating intertidal sediment from Jiaozhou Bay for 149 days in an anaerobic sequencing batch reactor?ASBR?.Nitrogen removal performance showed that the whole process could be divided into bacterial lysis phase,lag phase,exponential growth phase and stationary phase.When MAB were enriched successfully,the ammonium removal efficiency?ARE?and nitrite removal efficiency?NRE?achieved 100%and 83.03%,respectively.MAB sludge was taken for high-throughput sequencing,showing that Candidatus Scalindua and Candidatus Kuenenia were existed in the reactor and accounted for 10.21%and 3.21,respectively.During the enrichment of MAB,the sludge changed from black muddy to red granule.ASBR was used to study the nitrogen remove performance of MAB treating nitrogen-rich saline wastewater under nitrogen shock loadings.Ammonium removal rate?ARR?and nitrite removal rate?NRR?were 0.527 and 0.572 kg/?m³·d?when ammonium loading rate?ALR?and nitrite loading rate?NLR?were 0.681 and 0.888 kg/?m³·d?,respectively.Candidatus Scalindua were predominant in high saline surroundings and could tolerate high nitrite concentration under nitrogen shock loadings.The relative abundance of MAB was 17.07%.Marinicella could utilize nitrate produced by MAB.The coexisting MAB and Marinicella tended to account for the efficient removal of total nitrogen.Nitrogen removal performance was affected when influent nitrite was more than224.4 mg/L,resulting in a decrease of ARR and NRR to 0.358 and 0.310 kg/?m³·d?,respectively.However,the effect resulting from nitrite on MAB was reversible by decreasing influent NH₄⁺-N and NO₂^--N and the activity of MAB was recovered.Luong model was suitable to analyze inhibitory effect resulting from nitrite on MAB,and modified Aiba model could predict NRRmax under the dual effects resulting from nitrogen shock loadings and high saline surroundings.Marine anammox bacteria?MAB?were used to treat nitrogen-rich saline wastewater and nitrogen removal characteristics were studied with Fe???addition under nitrogen shock loadings.With 5 mg/L Fe???addition,ALR and NLR gradually increased from0.03 and 0.04 to 0.68 and 0.89 kg/?m³·d?,respectively.ARR and NRR reached maximal values of 0.56 and 0.60 kg/?m³·d?when ALR and NLR were 0.68 and 0.89 kg/?m³·d?,respectively.The value of?NO₂^--N/?NH₄⁺-N was lower than theoretical ratio due to existing marine Feammox process.The growth rate of MAB was accelerated by Fe???and it dominated in the reactor?27.70%?.Besides,MAB were synergized with Marinicella and Caldithrix to achieve higher total nitrogen removal.Haldane model was proper to analyze and predict the effect resulting from nitrite on the activity of MAB with Fe???addition under nitrogen shock loadings.