Study On Deep Denitrification Of Suspended Carrier Moving Bed Biofilm-activated Sludge Integrated SBR Process

With the rapid development of our country’s social economy and steady improvement of the level of urbanization,the problem in water environment environmental pollution has become extremely severe.The survey found that urban sewage in the south of our country is showing a trend of low carbonization,which makes it difficult to improve the nitrogen removal rate.This paper is based on the research group’s previous research on the denitrification of low-carbon sewage to carry out in-depth denitrification research,to achieve the purpose of deep denitrification of sewage.In the early stage,the sewage was subjected to an anoxic/aerobic sequencing batch activated sludge process（non-traditional anoxic/aerobic,influent-anoxic-precipitation-effluent-aerobic）effluent COD,NH₄⁺-N and TN concentrations were 38.64-51.92 mg/L,9.82-11.09 mg/L and 11.28-13.67 mg/L,in-depth denitrification research was carried out for this low-concentration sewage.the subject research used sawdust and corncob as biofilm carriers,which were placed in anoxic/aerobic sequencing batch reactors to construct SMBR and CMBR moving bed biofilm systems.By modifying the operating parameters and comparing the denitrification effects of SMBR and CMBR,the carrier material with a better denitrification effect was selected.Finally,the two-stage SBR reactor was operated with actual domestic sewage to investigate the overall effect of deep denitrification of sewage.The results of starting the film formation show that the biofilm formed on the surface of CMBR is thicker,the film formation time is shorter,and the treatment effect of various pollutants in the influent water is stable.the biofilm on the surface of SMBR is thinner,the time of film formation is longer,and the biological film distribution is more dispersed.CMBR reached a stable state on the 24th day and maintained a stable pollutant removal performance,which was 12 days earlier than that of SMBR.The research demonstrates that the TN removal rates of SMBR were 94.13%and72.70%,respectively,and the average NH₄⁺-N and TN effluent concentrations were 0.61mg/L and 3.21 mg/L,respectively.The TN removal effect in CMBR was better.With the increase of HRT,the TN removal rate of two reactors increased gradually.when the HRT was 8 h,little difference in the removal effects of NH₄⁺-N and COD between the two reactors can be found,the average TN removal rate of CMBR was 77.36%,the average TN effluent concentration was 2.76 mg/L,the average TN removal rate of SMBR was68.12%,and the average TN effluent concentration was 3.88 mg/L.The TN removal effect of CMBR was significantly better than that of SMBR.with increasing in the HRT,the increase in TN removal rate is low.With the increase of dissolved oxygen concentration,the removal rate of NH₄⁺-N increased significantly.when dissolved oxygen concentration was 2.2 mg/L,the average NH₄⁺-N removal rate of the two reactors was more than 90%,the average TN removal rate of the two reactors showed a trend of increasing at first and then decreasing.The average TN removal rate of SMBR reached a maximum of 72.52%when the dissolved oxygen was 1.6 mg/L,and the average TN effluent concentration was3.20 mg/L,The average TN removal rate of CMBR reached a maximum of 79.59%when the dissolved oxygen concentration was 2.2 mg/L,and the average TN effluent concentration was 2.42 mg/L.the average TN removal rate of CMBR was always higher than that of SMBR in the whole experiment.With the increase of influent C/N,the NH₄⁺-N in the two reactors was basically removed,and the average NH₄⁺-N removal rate was more than 90%.the average COD and TN removal rates of the two reactors gradually increased.When C/N was 4.0,the average TN removal rates of SMBR and CMBR were68.89%and 76.01%,respectively,and the average TN effluent concentrations were 3.51mg/L and 2.71 mg/L,respectively,Subsequent increase of influent C/N has no obvious increase in TN removal effect,which will cause a certain waste of resources.With the increase of influent p H,the removal rates of NH₄⁺-N and TN in the two reactors both showed a trend of increasing at first and then decreasing;when p H=8.0,the average NH₄⁺-N and TN removal rates of the two reactors reached the highest at the same time,the average NH₄⁺-N and TN removal rates of SMBR were 95.12%and 73.32%,respectively,and the average NH₄⁺-N and TN effluent concentrations were 0.52 mg/L and 3.15 mg/L,respectively,the average NH₄⁺-N and TN removal rates of CMBR were respectively,the average NH₄⁺-N and TN effluent concentrations were 0.57 mg/L and 2.40 mg/L,respectively.During the test,CMBR was better than SMBR in removing pollutants.By running the two-stage SBR process（The first stage is anoxic/aerobic sequencing batch activated sludge process,and the second stage is a suspended carrier moving bed biofilm-activated sludge integrated SBR process）to treat actual domestic sewage,the good treatment effect is achieved.During the test period,the average COD,NH₄⁺-N and TN influent concentrations of the two-stage SBR were 157.72 mg/L,35.79 mg/L and 39.71mg/L,respectively.after the stable operation,the average COD,NH₄⁺-N and TN effluent concentrations of SBRⅠwere 44.76 mg/L,11.22 mg/L and 13.04 mg/L respectively.The average COD,NH₄⁺-N and TN effluent concentrations after SBRⅡwere 15.03 mg/L,0.48mg/L and 2.41 mg/L,respectively.The average COD removal rate of the two-stage SBR system was 90.38%,the average NH₄⁺-N removal rate was 98.63%,and the average TN removal rate was 93.86%.The two-stage SBR system achieved the purpose of deep denitrification of sewage.Figure[29]Table[4]References[124]...