Study On Denitrification Performance Of Sulfate Wastewater Treatment By UASB Reactor

In modern industrial production,coal-fired power plants and other industries emit a large number of sulfate and ammonia nitrogen wastewater in the production process.In this study,two UASB reactors were operated in series,which were divided into sulfate reduction denitrification（SR-DR）unit and denitrification desulfurization（DSR）unit.The removal efficiency of carbon,nitrogen and sulfur in SR-DR and DSR units during salt tolerance and acclimation was investigated,and the effects of COD/SO₄^2-of 0.3 and 1 on the removal of carbon,nitrogen and sulfur were analyzed when the acclimation was completed.Finally,high throughput sequencing technique was used to study the diversity and dominant strains of microbial communities in SR-DR and DSR reaction units during stable operation and gradually increasing COD/SO₄^2-to 1 SR-DR and DSR reaction units.Salt-tolerant acclimation of activated sludge was carried out by increasing sulfate concentration（1g/L,2g/L,3g/L,5g/L,10g/L）and nitrate nitrogen concentration（30mg/L,100mg/L,200mg/L,300mg/L）.The dissolved oxygen of reactions is DO=0⁰.2mg/L,ORP is-375±25mv,HRT is 24 h,pH is 7.6±0.2.The results show that the removal rate of nitrate can reach over 80%under the stable operation of the SR-DR reaction unit,and most of the nitrate can be removed.The removal rates of residual nitrate in dsr reaction unit were over 85%,and the sulfate removal rates in SR-DR and DSR units were 32.3%and 45.9%,respectively.With the increase of sulfate concentration,the removal rate of sulfate in the reaction unit decreased.Influent COD/SO₄^2-is an important parameter that affects the competition between sulfate reducing bacteria and other anaerobes in the treatment of anaerobic wastewater.In order to achieve the best nitrogen removal effect,the operating condition is the same as the stable operation stage,and the COD/SO₄^2-is 0.3,0.5 and1,respectively.The results show that the removal rate of the nitrate is maintained above 95%,and most of the nitrate can be removed.The removal rate of nitrate in the reaction unit of the DSR is not stable,from 90%to about 15%,and the accumulation of nitrite is obvious.The removal rate of the sulfate is reduced,the sulfate removal rate of the highest point is increased,the removal rate of the sulfate is lower than 5%,and the removal of the sulfate is basically free.Through high-throughput sequencing,the structure of the microbial community in the reactor is obvious,and the main dominant species are distributed in different classes or genera.and the main dominant bacteria were distributed in different classes or genus.It has been detected that Alphaproteobacteria,Betaproteobacteria and Gammaproteobacteria,Bacteroidete Sphingobacteriia and Chloroflexi are the dominant strains in the process treatment of proteus.