Study On Nigtrogen Removal Efficiency And Influencing Factors Of Sulfate Reduction Anaerobic Ammonia Oxidation

In the process of economic and industrial development,industrial wastewater has become increasingly complex(containing pollutants such as ammonia nitrogen,sulfate and heavy metals).Conventional anaerobic ammonia oxidation(ANAMMOX)process has good denitrification performance.However,high sensitivity to the environment.Complex water environnent(such as:high sulfate content)can inhibit the denitrification performance of ANAMMOX process.Sulfate-reducing anaerobie ammonia oxidation(SRAO)reaction ean remove nitrogen and sulfur simultaneously,providing a new approach for complex industrial wastewater treatment.In this work,the start-up of anaerobic ammonia oxidation was investigated using sulfate as substrate under inorganic conditions and efficient treatment of pollutants at the same time.In the ANAMMOX start-up process,an anaerobic sequencing batch reactor was used.After 120 days,the process reached the stable state.The reactor with sulfate injection exhibited a good e:ffluent effect and achieved simultaneous nitrogen and sulfur removal.The commonly observed accumulation of NO3"-N in the conventional ANAMMOX reaction was alleviated.The TN removal rate reached 87.1%after the SRAO reactor was successfully started,which was higher than that of the ANAMMOX reactor.The effect of sulfate on the denitrification performance of ANAMMOX under different operating conditions was investigated.The results showed that the optimum HRT for the denitrification process of SRAO was 48 h.Increasing the N/S concentration ratio is beneficial to improving the removal capacity of the substrate,in which the TN removal rate is 85.8%and S042" removal rate is 74.2%.The microbial species distribution under different N/S concentration ratios is analyzed by high-throughput sequencing.Denitrification effect of the reaction system was best when the COD concentration in the water was 200 mg/L.Certain concentrations of NO3--N and NO2--N can improve the denitrification effect of the reaction system.The inhibition of heavy metals(e.g.,Cu2+and Zn2+)on SRAO was investigated.The results showed that certain concentrations of heavy metals(i.e.5 Cu2+<1.2 mg/L,and Zn2+?2.0 mg/L)could improve the denitrification performance.A high concentration of heavy metals inhibited sludge activity,however,the tolerance of the sludge was high.After a period of acclimation,the sludge activity gradually recovered.Through high-throughput sequencing,two characteristic bacteria {Bacillus benzoevorans and Thioplaca)were found in the SRAO reactor which could use sulfate as the substrate.B.benzoevoran is a characteristic bacterium for the SRAO reaction,accounting for 17.2%of the species.Thioplaca is a sulfur autotrophic denitrifying bacterium,accounting for 5.9%of the species.The proportion of ANAMMOX bacteria in the SRAO reactor treated with sulfate decreased by 4.6 percent compared with the ANAMMOX reactor treated without sulfate.In this study,the ANAMMOX reactor was started with sulfate as the substrate.The optimum denitrification performance of the SRAO reactor was also investigated.It not only provides a new idea for the cultivation of anaerobic sludge,but also basic data and practical experience for the start-up of anaerobic ammonia oxidation reactor,and to the improvement ANAMMOX performance.