Research On The Startup, Operation And Optimization Strategy Of The ANAMMOX Simultaneous Denitrification And Desulfurization Coupling Process Based On Sulfur Autotrophic Denitrification

With the increasing of sulfur and nitrogen compounds industrial wastewater discharge,compared with the physicochemical method to remove pollutants in wastewater,the biological method of activated sludge has the advantages of mild reaction conditions,low energy consumption and low investment,which were favored by people.Therefore,this project mainly took the sulfide and nitrate containing wastewater of artificial simulation as the treatment object,and initiated sulfur-based autotrophic denitrification?SAD?process based on sequencing batch reactor?SBR?.According to the characteristics of SAD process,simultaneous nitrogen and sulfur removal and stable accumulation of nitrite were studied under different S/N technologies,so as to provide reaction substrates for subsequent anaerobic ammonia oxidation?Anammox?process and achieve deep nitrogen removal by combination process.Meanwhile,according to the characteristics of anammox bacteria,graphene oxide?GO?was used as an additive to improve the denitrification performance of anammox bacteria.?1?The autotrophic denitrification process driven by sulfide as electron donor was studied by inoculating residual activated sludge from secondary sedimentation tank in SBR reactor.The results showed that SAD reactor was successfully started at 22d.When S/N was 1.45,the removal rates of NO₃^-and S^2-were 95.8%and 100%,respectively.When the S/N decreased to 0.94,NO₂^-was found in the effluent for the first time.When S/N was 0.8,NO₂^-achieved continuous accumulation and the maximum accumulation rate was 55.3%.The results of batch experiments showed that when S/N was 0.8,the effect of NO₂^-accumulation was the best.And the accumulation of NO₂^-increased with increasing of NO₃^-concentration.In addition,the microbial community also changed after the startup of system through high-throughput analysis.The results showed that Proteobacteria?59.5%-84%?was the main phylum.Thiobacillus?3.8%-2.1%?,as the main function bacteria of SAD,could remove both sulfide and nitrate simultaneously.Meanwhile,one of the high abundant genus Arenimonas?11.4%-28.2%?was heterotrophic denitrifying bacteria and the other one was photoautotrophic genus named uncultured?f?Chromatiaceae?5.7%-27.5%?,which were also involved in the removal of pollutants in SAD system.?2?After activated SAD system and accumulated NO₂^-stably,it was combined with the same volume of ANAMMOX-SBR reactor.The effluent of SAD system was supplemented with NH₄⁺as the influent of ANAMMOX system,and the feasibility study of SAD+ANAMMOX combined process was conducted to achieve the simultaneous removal of S^2-,NO₃^-and NH₄⁺pollutants as the main purpose.The results showed that the combined process was operated for 56d.At 0-30d,the combined process ran stably,the total nitrogen removal rate was up to over 94.3%,and the S^2-removal rate was 100%.However,with the increase of substrate concentration load in SAD system,at 31-56d,ANAMMOX system was affected by the possible presence of sulfur-containing by-products in the effluent of SAD process,the activity of Anammox bacteria decreased as the total nitrogen removal rate decreased.?3?Due to the characteristics of Anammox bacteria that was difficult to be cultured and low growth rate,the flocculent Anammox sludge acclimated in the laboratory was used as the research object,and the activity of Anammox bacteria was enhanced with GO as the additive to improve the denitrification performance.Firstly,GO were prepared according to the improved Hummers method,and its structure was characterized by various characterization methods?such as FTIR,XRD,SEM,BET?.Secondly,the effects of different doses of GO on Anammox bacteria were studied through batch tests.The results showed that when the GO concentration was below 0.15g/L,the nitrogen removal performance of Anammox bacteria would increase with the increase of GO concentration.When the GO dose was 0.15g/L,the denitrification performance was the best,and the total nitrogen removal rate was 18.6%higher than the control group.However,when the GO dose reached 0.2g/L,the activity of Anammox bacteria was inhibited,and the total nitrogen removal rate was 26.0%lower than that of the control group.Through the control experiment,the effect of adding GO or without GO on the nitrogen removal performance of the Anammox reactor running continuously was studied.The results showed that the average total nitrogen removal rates of R2 reactor with GO addition at each substrate concentration stage were 85.3%,83.2%,81.1%,80.8%,respectively.The nitrogen removal performance of these groups were higher than R1 reactor without GO.The kinetics characteristics of nitrogen removal in a single cycle of the R2 reactor were evaluated.The modified Boltzmann and Gompertz model were found to be the appropriate models to describe the denitrification performance of the R2 reactor in a single cycle.Moreover,the formula to predict the total nitrogen effluent concentration and removal rate at any time in the cycle was obtained.