Research On The Effect Of Nitrification And Denitrification By Adding PAC In Activated Sludge

For domestic sewage,the further study of the influence of nitrification and denitrification in adding PAC in reflow sludge method,for efficient wastewater treatment,reasonable additive powder activated carbon,reduce the operation cost of sewage treatment plant,improve the nitrification and denitrification rate has important practical significance.This paper mainly used SBR process to treat domestic sewage,by adjusting additive amount of powder activated carbon and Settling timentation time,after analysis under different conditions,the research of powder activated carbon,and the effects of nitrification and denitrification of wastewater,the impact on the amount of sludge and sludge characteristics,and the influence of different initial setting time on the microbial,nitrification and denitrification of adding PAC in reflow sludge method provide certain theoretical basis.The results showed that:1.Powder activated carbon in the process of denitrification and phosphorus removal in SBR reactor effluent has optimization effect.Specific studies are as follows:(1)The change of the different amount of powder activated carbon in SBR had significant effect on the removal of COD,TN,TP.The results show that:The amount of powder activated carbon is 0.04 g/L,COD removal rate than the control group respectively was increased by 10%;TN removal rate than the control group respectively increased by 29%;TP removal rate than the control group respectively increased by 7.5%,respectively.Thus,0.04 g/L was the optimal dosing quantity of powder activated carbon.(2)The change of Settling timentation time had significant effect on the removal of COD,TN,TP,which is obvious when the time is 30min.The results showed that:Settling time is 30 min,COD removal rate than the control group respectively was increased by 3%;TN removal rate than the control group respectively increased by 3.7%;TP removal rate than the control group respectively increased by 3.2%,respectively.Thus,30 min is the best time.2.Powder activated carbon in the process of denitrification and phosphorus removal in SBR reactor effluent has optimization effect.After analysis under different conditions,the research of powder activated carbon,and the effects of nitrification and denitrification of wastewater.Specific studies are as follows:(1)The amount of sludge and sludge apparent yield with the amount of powder activated carbon and Settling timentation time is not obvious.But as the quantity of powder activated carbon changing,MLSS and apparent yield of sludge are first rise after falling.Powder activated carbon amount gradually increases,the specific yield coefficient from 0.562 to 0.582 mgMLSS/mgCODcr,then reduce to 0.567mgMLSS/mgCODcr.Therefore,the powder activated carbon additive quantity is 0.04 g/L,the increased rate of MLSS,fastest sludge apparent yield was the highest.(2)With Settling time changing,the time of 0 min,10 min,30 min,60 min,120 min of nitrification rate is 12.20 mg/(g,h),12.40 mg/(g,h),13.08 mg/(g,h),12.50 mg/(g,h),12.07 mg/(g,h).Thus,the time in 30 min,the nitrification rate is the largest.(3)With Settling time changing,the time of 0 min,10 min,30 min,60 min,120 min of nitrification rate is 6.80 mg/(g,h),6.81 mg/(g,h),7.08 mg/(g,h),6.90 mg/(g,h),6.8 mg/(g,h).Thus:the time in 30 min,the denitrification rate is the largest,much smaller than the nitrification rate,this is consistent with the water quality indicators.3.By controlling Settling timentation time,After analysis under different conditions,in running the system under different working condition untill stability,cultivating number of functional genes,to analyze the influence of nitrification and denitrification of functional genes in adding PAC in reflow sludge method.Main conclusions are the following:(1)With the different Settling time,the number of AOB genes corresponds to the control group had obvious changes.the time for 30 min,the number of genes were higher than the time of 1 h and four parallel sample averages.Thus:After the heavy nitrification effect is higher than at the beginning of the direct additive powder activated carbon,and the time of 30 min of nitrification effect is best,so early is not heavy,the longer it is nitration the better the results.(2)With the different Settling time,the number of nirK,nirS genes corresponds to the control group had obvious change.the time for 30 min,the number of genes were higher than the time of 1 h and the control group the average amount of nirK genes;The time for 30 min,averages for the number of nirS gene were higher than the time of 1 h and the control groupaverage number of nirS gene.This shows:After the heavy denitrifying effect is higher than at the beginning of the denitrification effect of directly adding the powder activated carbon,and the time of 30 min denitrifying effect is best,but the number of nirK,nirS genes gap than the disparity between the number of AOB genes,also explains the effect of nitrification and denitrification effect more apparent.