Research On The Removal Efficiency Of Ibuprofen And Microbial Diversity Of Urban Sewage Treatment By TDE-BAF

In the light of conventional wastewater treatment process,the degradation efficiency of the refractory PPCPs organic compounds represented by ibuprofen in municipal wastewater is weak,and the structure of ibuprofen is complex and the activation energy is high.According to the internal operational characteristics of BAF and TDE,we proposed the municipal sewage in typical refractory PPCPs organic matter removal by TDE-BAF hypothesis.The sorption functional media(SFM)and red mud particle electrode(RMPE)were prepared on the basis of optimal screening.Based on the stimulation effect of electric field on microbial population,TDE-BAF system was constructed to remove ibuprofen in municipal wastewater.The key control parameters of the TDE-BAF system were screened,and the quantitative relationship between the key control parameters and the efficiency of pollutant removal was established.The removal efficiency and spatial removal characteristics of TDE-BAF system were also studied.In addition,the high throughput sequencing technique was used to reveal the effects of electric field on the structure and diversity of microbial communities,thus providing a new theoretical basis and technical support for degradation of ibuprofen in municipal wastewater.The sorption functional media(SFM)could be prepared from the mixture of zeolite tailings,pore-forming material and clay by heating at 1150?C for 30 min,and the proper mass ratio of zeolite tailings,clay and pore-forming material was 14:4:3.The sorption and desorption isotherm of ammonia nitrogen on SFM could be wel l described by the Langmuir formula.Low temperature(6-11?C)showed a more significant influence on NH3-N removal and COD removal for both SFM BAF and haydite BAF.The test results proved that the SFM BAF has a stronger adaptability to low temperature for NH3-N removal compared to haydite BAF.The red mud particle electrode(RMPE)could be prepared from the mixture of industrial waste-red muds,zeolite tailings,pore-forming material-carbon and iron powder by heating at 1000 ?C for 10 min,and the proper mass ratio of red muds,zeolite tailings and iron powder was 5:3:2,the proportion of carbon 5%.RMPEs contain transition metal and rare metal oxide content as high as 40.46%.Taking SFM and RMPE as fillers,the effect stimulation of current on microbial population was investigated,and the effects of plate spacing,RMPE and SFM height ratio on degradation of ibuprofen were also investigated.The results showed th at he current promotes microbial growth,microbial diversity and microbial degrading enzyme activity in a certain electric current density range,speeds up the reflection rate and improves the removal rate of pollutants.The higher current density may inhibit the growth of some microorganisms,reduce the biological community and decrease the removal efficiency of pollutants.when the RMPEs and SFM height ratio of 1:4(the height of RMPEs is 300 mm,the height of SFMs is 1200cm)and the plate spacing is 10 cm,the removal efficiency of efficient removal of municipal wastewater is very high and the TDE-BAF reactor was constructed.Compared with the single BAF reactor,the TDE-BAF reactor has fast biofilm formation speed and high removal efficiency of COD and ammonia nitrogen during the acclimation period.Taking the municipal wastewater as the treatment object,the PPCPs typical substance-ibuprofen as the target pollutant,the dynamic experiment was carried out.The response surface method was used to screen the key control parameters in the TDE-BAF,and to establish quantitative relationship between current density(CD),hydraulic retention time(HRT),ibuprofen concentrate and the removal rates of COD,ammonia nitrogen,ibuprofen.The optimal process conditions in TDE-BAF for the simultaneous removal of COD,NH4+-N and ibuprofen are CD 12.73A/m2,HRT 3.5h and the ibuprofen concentrate 0.09mg/L.The interaction of CD,HRT and ibuprofen concentrate has obvious influence on the removal rate of COD,NH4+-N and ibuprofen.When CD 12.73A/m2 and HRT 3.5h,the average removal rate of COD,TOC,ibuprofen and NH4+-N in TDE-BAF was 86.72%,81.91%,93.48% and 85.19%,respectively,which increased by 14.57%,19.83%,61.56% and 10.49% respectively compared with single BAF.The COD and TOC removal in TDE-BAF is mainly concentrated in the area of the filter material layer thickness less than 90 cm.The removal rate of ibuprofen in the TDE region was 51.78%,which accounted for 55.40% of the total removal rate.Nitrification was concentrated in the thickness of 60cm-150cm(T3-T6)region,accounting for the total removal rate of ammonia nitrogen 53.85%.In the case of TDE-BAF stable operation,the dynamic variation of the microbial community structure and diversity in the TDE-BAF with current density,PPCPs load and backwashing was studied by using the Miseq high throughput sequencing technology and the BAF as the reference.When CD is 12.73A/m2,the microbial diversity in the upper of TDE-BAF is low,while the lower microbial diversity is high.Due to the presence of current in the upper region,the difference of microbial diversity was greater in between the upper and lower parts of the TDE-BAF as well as the same parts of the single BAF.At the genus level,the dominant bacteria genus in the upper region of TDE-BAF include Trichococcus(12.68%)?Aeromonas(12.66%)?Flavobacterium(5.97%)?Sphingopyxis(5.40%)?Candidate_division_TM7_Norank(5.12%)?Acinetobacter(5.09%)?Saprospiraceae_uncultured(4.95%)?Methylophilus(4.39%)?Rheinheimera(3.8%)?Erwinia(3.37%),while the dominant bacteria genus in the lower region is Saprospiraceae_uncultured(9.75%)?Thiobacillus(7.34%)?Aeromonas(6.35%)?Candidate_division_TM7_norank(5.18%)?Runella(4.81%)?Erwinia(4.56%)?Flavobacterium(4.38%)?Nannocystis(3.55%).CD and PPCPs load have similar effects on microbial diversity in TDE-BAF.Before and after the anti flushing,OTUs,Ace,Chao,Shannon and Simpson indices all showed that the diversity of microbial community in TDE-BAF was gradually decreased along the height of the reactor before and after the backwashing.In the upper part of TDE-BAF reactor,the diversity of the microbial community was increased after the backwashing,while the lower part was the opposite,and the similar results also existed in the BAF reactor.