Effluent Quality Improvement And Efficient Operation By Chemical Enhanced Biological Aerated Filter

Water pollution has become more and more serious with the development of economy inour country. Particularly in recent years, the phenomenon of eutrophication in our countrybecomes more and more serious. Excessive amounts of nitrogen and phosphorus in the wateris the direct cause of eutrophication of water bodies. For controlling eutrophication from rootcauses, effulunt nitrogen and phosphorus should be treated to standard in sewage plant.Withthe quick pace of urban development, land resources shortage has become more and moreserious. Therefore, Sewage factory is severely restricted when it occupys too much land.However, Biological Aerated Filters for wastewater treatment has better treatment effect andsmall footprint. Therefore, BAF is widely used in recent years. The biggest deficiency ofBiological aerated filter process is that the phosphorus removal effect is bad. With theimprovement of wastewater discharge standard, most domestic BAF sewage treatment plantneed to be reconstructed. Technology research is rarely studied which uses chemicalreinforcement and process optimization to improve the water quality in situ modification.Biological aerated filter process of Shaying sewage plant is representative. Therefore,this test chooses Shengli oil field Shaying sewage plant front denitrifying two-stage BAFprocess as the research object. The study is based on the optimization of front chemicallyenhanced coagulant, the characteristics of the process parameters and research of filtermicrobial activity. Which conclusioned that the suitable method for sand camp sewagetreatment plant was upgrade in-place modification technology. This study provides referencefor the renovation of the BAF sewage treatment process.Coagulant optimization showed that PAC was chosed as the chemically enhancedcoagulant by sewage plant since it was technically feasible and economically optimal.Because, TP removal effect are closely associated with coagulant dosing, TP removal effect inBAF is poor, TP concentration was chosed as the control parameters for dosing. Studies haveshown that coagulant dosing position is sedimentation tank inlet.PAC compound with PAMdosing was studied. PAC compound with PAM on COD, TP and turbidity removal effect isimproved. But by adding PAC dosing quantity can achieve removal effect equal to compoundwith PAM, and the former is more economic and reasonable. The study about COD concentration and temperature to the effect of TP removal shows that TP removal efficiencyreduced with the increase of COD concentration, temperature have little influence on removaleffect of TP.The removal rate of COD in chemically enhanced front denitrifying two-stage BAFprocess is more than85%. NH3-N removal rate is around95%. TP removal rate is75%. Theeffluent COD and NH3-N meet the level of A standard. The effluent TP meet the level of Bstandard.CN filter dissolved oxygen have little effect on COD and TP removal efficiency, but theinfluence of NH3-N is big, the optimal values of dissolved oxygen is6.5mg/L. Reflux ratiohave little influence on COD and TP removal efficiency, NH3-N and TN removal efficiencyincreased with the increase of reflux ratio increased, the optimal values of reflux ratio is2.0.COD and NH3-N removal rate increased with the increase of temperature, temperature havelittle influence on TP removal efficiency.Backwash cycle studies have shown that the change of COD in denitrification DN filtercould be chosed as backwash reference index. The summer backwash cycle is96h. Winterbackwash cycle is72h. CN filter backwash indicator is change of NH3-N. The summerbackwash cycle is108h.winter backwash cycle is90h.To study the aerobic rate of filter material biofilm and back flush sludge of CN filter.Aerobic rate of CN filter ceramsite and surface biofilm is0.46mg O2/(g ceramsite h). Aerobicrate of CN filter filter material surface volatile solid biofilm is75.32mg O2/(g MLVSS, h).Aerobic rate of CN filter volatile solid back flush sludge is78.19mg O2/(g MLVSS, h). Theresearch of CN filter backwashing sludge nitrification rate showed that: On the basis of addedcarbon source, nitration reaction rate of CN filter back flush sludge is1.48mg of NH3-N/(gMLSS, h). The study of DN filter back flush sludge denitrification rate showed that, backflush sludge denitrification reaction has three obvious stages. The first stage time is about0-90min, denitrification rate is15.84mg/(g MLVSS, h).The second stage time is about90-240min, denitrification rate is4.09mg/(g MLVSS, h). The third stage time is about240-360min, denitrification rate is0.90mg/(g MLVSS, h). The comparative study beweenfilter microbial activity with dosing-coagulant and no-dosing coagulant showed that it had noeffect on biological activity in denitrification filter/BAF process by front dosing PAC. Front dosing chemical strengthen coagulants on subsequent BAF process has littleinfluence on microbial activity. Microscopy and scanning electron microscopy (SEM) showedthat biofacies in BAF were abundant and the populations were various.