The Biotransformation Pathway Of Ammonia And Sulfate And Its Molecular Biology Analysis In ANAMMOX System

The simultaneous conversion of ammonia and sulfate in anaerobic ammonium oxidation system has long been considered as the biotransformation between ammonia and sulfate under the action of anammox bacteria.However,in the related research reports,the conversion phenomenon of ammonia and sulfate have contradictions such as large difference in N/S molar conversion ratio and unclear product with the conversion mechanism.In recent years,a new explanation has been proposed.The phenomenon of sulfate reduction and ammonia oxidation is the independent conversion of ammonia and sulfate.The ammonia is oxidized by the oxygen entering the reactor under the action of ammonia oxidizing bacteria.The sulfate undergoes heterotrophic reduction by organisms released from microbial decay under the action of sulfate reducing bacteria.The evidence for this new view is weak.It still lacks the detection data of related bacterial communities and functional microorganisms in the simultaneous transformation process and the detection data of carbon sources and products in the process of sulfate conversion.Based on the existing problems in the researches,this study use continuous flow and batch experiments to detect matrix concentration,ORP,and carbon source data during the experiment.Microbial community structure changes and Microbial abundance changes of functional genes like apsA,amoA,narG,hzsB of sludge samples with long-term stable simultaneous transformation were determined by high-throughput sequencing.Through the means and methods above,the main content of this study was three aspects:?1?general conditions of simultaneous conversion of NH₄⁺and SO₄^2-in the ANAMMOX system;?2?detection data of carbon source and products in the process of sulfate conversion;?3?detection data of bacterial community changes and functional microbial abundance during the occurrence of simultaneous transformation.Through the experimental data demonstration and literature comparison analysis,the following main conclusions were drawn:1)The conditions for the simultaneous conversion of NH₄⁺and SO₄^2-are:inoculating mixed sludge?the ratio of ANAMMOX sludge and concentrate sludge of sewage plant was 1:1?,sufficient NH₄⁺and SO₄^2-,and the ORP value within the appropriate range??150mV^?250mV?.The influencing factors of the ORP value are:the oxygen brought in by influent mode,the NH₄⁺conversion consumes dissolved oxygen,and the TOC released by the sludge decay consumes dissolved oxygen.2)Both TOC and S^2-are lower than the detection limit during the continuous conversion phenomenon.TOC accumulation has been detected in batch reactors.And SO₄^2-total conversion is 53.59 mg·L^-1,with the S^2-content in the system is 6.26 mg·L^-1.The loss of sulfur-containing components is about 88%.3)Sequencing results of microbial flora and functional genes indicated that in the CFSTR2 experiment?inoculated mixed sludge?to achieve long-term stable simultaneous transformation,the abundance of the bacterias containing amoA,apsA and narG increased noticeably,related to the reaction process.The abundance of the bacterias containing hzsB changed little before and after the reaction,the increase was less than0.04%.Because the anaerobic ammonia oxidizing bacteria is the dominant bacteria in the system,the low increase still had a higher proportion of the total number of bacteria.The increase in abundance of functional bacteria indicates that the main reactions in the system are ammonia oxidation,anaerobic ammonium oxidation,denitrification and sulfate reduction.Combining with the research experiment and analysis of the literature,the conditions for the simultaneous transformation phenomenon obtained in this paper are consistent with the experimental conditions in the relevant literature.The ammonia oxidation,anaerobic ammonium oxidation,denitrification and sulfate reduction functional bacteria detected in this paper also appeared in the detection data of relevant literature.Therefore,the experimental conditions of this paper are the general conditions for the simultaneous conversion phenomenon.The simultaneous conversion phenomena observed in this paper and related researches are independent conversion of NH₄⁺and SO₄^2-.NH₄⁺is oxygenated into the system under the action of AOB.SO₄^2-consumed is a heterotrophic reduction by organisms?TOC?released from microbial decay.