Performance And Microbial Community Structure Of Step Feed A/O Process For Treating Comprehensive Wastewater From Hair Product Production Cluster Area

Due to complicated and fluctuant component in comprehensive wastewater from hair product production cluster area,it is necessary to further verify the effectiveness of the existing treatment processes to treat the comprehensive wastewater,but developing new technology is more agog so it can be guaranteed that effluent cater to emission standard.In this study,we designed and applied step feed A/O process to treat comprehensive wastewater from hair product production cluster area.Significant parameters influencing operation performance were studied,including hydraulic retention time(HRT),influent flow distribution,volume distribution ratio of anoxic zone and oxic zone(volume distribution)and sludge return ratio.Meanwhile,we also applied biotechnologies including qPCR and Illumina Mi-seq to reveal relationship among technical parameters,contaminant tremoval and microbial community structure/function.Aiming at DO carryover to anoxic zones,week elimination capacity of phosphorus and sludge bulking in step feed A/O process,we proposed solutions and verified the feasibility of these solutions.Then in order to investigate the stability and economy,pilot scale step feed A/O process was operated to deal with comprehensive wastewater from hair product production cluster area,about 36 tons every day.Main content and conclusions of this study were as follows:(1)Dealing with the comprehensive wastewater from hair product production cluster area,optimal operation parameters of the step feed A/O process were:HRT 16 h,inflow distribution 60%:25%:15%,anoxic zone and aerobic zone volume ratio 1:1,sludge return ratio 75%.At this time,COD,NH4+-N and TN reached the I-A discharge standard of GB18918-2002.(2)The step feed A/O process was suitable for dealing with COD and NH4+-N,removal efficencies reached 90%under different operating conditions.(3)The removal efficiencies of PO43--P reached the maximum,49.18%,with the inflow distribution 40%:35%:25%.The denitrification process controlled by denitrifying functional gene nosZ successfully improved with the inflow distribution 60%:25%:15%,then the process got the highest TN removal rate,41.60%.Contaminant removal rates varied with inflow distribution might be related to the variation of some main microbial community structure in genus classification level,for example,uncultured-f-Hydrogenophilacea,norank-o-Obscuribacterales,uncultured-f-Saprospiraceae,SM1AO2,Denitratisoma,unclassified-p-Bacteroidetes,Thauera,unclassified-f-Comamonadacae and Novosphingobium.(4)The removal efficiencies of PO043--P reached the maximum,77.03%,with the volume distribution 2:1.The denitrification process controlled by denitrifying functional gene napA successfully improved with the volume distribution 1:1,then the process got the highest TN removal rate,41.60%.Pollutants removal rates varied with volume distribution might be related to the variation of some main microbial community structure in genus classification level,for example,Denitratisoma unclassified-f-Comamonadaceae,norank-p-Candidate-division-WS6 and Thauera(5)The removal efficiencies of COD,PO43--P and TN increased when the sludge return ratio decreased.When sludge return ratio was 75%,the removal efficiencies of COD,PO43--P and TN were 92.08%,40.90%and 53.84%.The number of denitrification function genes narG,napA,nirS,nirK and nosZ became larger in lower sludge return ratio.Pollutants removal rates varied with sludge return ratio might be related to the variation of some main microbial community structure in genus classification level,like Sulfuritalea,unclassified-f-Comamonadaceae,uncultured-f-Anaerolineaceae,Denitratisoma,norank-p-Candidate-division-WS6,uncultured-f-Nitrosomonadaceae,Thauera and Phaeodactylibacter.(6)The measure,adding moderate PAC into effluent from step feed A/O process so that PAC mass concentration was approximately 90mg/L,assured TP mass concentration was less than 0.50mg/L in effluent at the last.(7)The step-feed A/O process was operated to SBR process temporarily,and an integrated method efficiently controlled sludge bulking tempted by unknown cause The integrated method included alternating aeration conditions;enhancing COD to 332.73±106.06mg/L;increasing DO to 7.45±0.49mg/L during aeration;adding FeCl3 into the reactor in the start of settling phase of the SBR process that FeC13 mass concentration was approximately 120mg/L.With the integrated method SVI dropped from 274mL/g to 56mL/g within 13 days(8)With optimal operation parameters,pilot scale three step feed A/O process,which was applied to deal with comprehensive wastewater from hair product production cluster area,36 tons every day,got stable water quality discharged that met the I-A discharge standard in China.The cost was 0.39 yuan dealing with each ton of comprehensive wastewater.