Study On The Whole Process Mathematical Model Of SBR-BCO Denitrifying Phosphorus Removal Technology

The current eutrophication problem in our country is still grim.Nitrogen and phosphorus emissions of sewage treatment technology is becoming more and more strict,so a more advanced and efficient processing technology is badly in need.Double sludge denitrifying phosphorus removal technology which has solved the traditional biological denitrification process of contradiction,the carbon source competition and sludge age,has a broad application prospect.Our Research of the organic combination of SBR and contact oxidation process has developed a new type of SBR-BCO denitrifying phosphorus removal process（SBR-BCO process）,compared with the traditional biological denitrification and phosphorus removal process,which has many advantages.This paper,based on simplified biological nitrogen and phosphorus removal dynamics model,attempts to build the mathematical model of the whole process of SBR-BCO denitrifying phosphorus removal system,estimate and validate the model parameter through test.The main research contents and results are as follows:For model parameter estimation and model validation data,design SBR-BCO test device and continue operation.This paper first introduces respectively the dynamic treatment effect of the operation process under conditions of simulated domestic sewage and real sewage.In two kinds of cases,the operating condition of anaerobic period,nitration,anoxic period,re-aeration time respectively for 3 h,4 h,8 h,2 h（simulated sewage）;2 h,4 h,8 h,1 h（actual sewage）.Experimental results show that under the two kinds of condition,system has a good effect of COD,ammonia nitrogen,TN,TP removal.At simulated sewage phase,the average removal rates are 90.00%,87.98%,79.40%and 95.72%respectively,the effluent average concentration of 21.53 mg/l,3.88mg/l,9.25 mg/l,0.20 mg/l respectively;at actual sewage phase,the average removal rate of 92.19%,86.02%,73.07%,81.96%,the effluent average concentration of 10.45 mg/l,3.35 mg/l,9.0 mg/l,0.37 mg/l respectively.Based on reaction kinetics model and chemometrics relationship of SBR-BCO system in our early research,with the material balance principle,a model of the whole process with COD,TP,TN,PHB,ammonia nitrogen,NO₃^--N as variables in every reaction stage（unit）is constructed.Through the static phosphorus release and phosphate-accumulating test,estimate the anaerobic COD degradation rate constant k _COD-y,anoxic PHB rate constant K_PHB-q,anoxic phosphorus-accumulating rate constant（phosphorus deficiency）k_lim-q,re-aeration PHB consumption rate constant k _PHB-H,re-aeration phosphorus-accumulating rate constant k _PP-H（phosphorus deficiency）,re-aeration COD degradation rate constant k _COD-H,nitrification rate constantof re-aeration period k _NO-H,bacteriolysis constant b_zr-H,total yield constant Y_o-H,COD degradation rate constant of nitrification period K_COD-N,nitrification rate constant K_NO-N,bacteriolysis constant in nitrification period b _N,total yield coefficient in nitrification period Y_O-N,metrology relationship between COD consumption and release of phosphorus amountν_{（P.COD）-y}in anaerobic period,and metrology relationship between PHB synthesis amount and phosphorus release amountν_{（P,PHB）-y}in,anaerobic period,metrology relationship between anoxic period phosphorus-accumulating and PHB consumptionν_{（PHB.PP）-q},metrology relationship between nitrogen removal and PHB consumptionν_{（PHB.NO）-q},metrology relationship between consumption of PHB and aerobic phosphorus-accumulatingν_{（PHB.PP）-H}such values as model parameters,which lays the important foundation for the application of the model.The SBR-BCO continuous operation test data,respectively,in simulated sewage wastewater quality and the real sewage wastewater quality conditions,verify this model.Results show that with the consideration of the accuracy of engineering application,the model can better simulate the change rule of pollutants in every reaction order（units）.Under the condition of simulated sewage,relative error ranges of the simulation values and predicted values for COD,ammonia nitrogen,TN,TP,PHB,nitrate in effluent of each reaction stage（unit）are 6.24%-14.67%、3.30%-17.58%、5.41%-10.37%、5.75%-18.63%、6.12%-12.92%、6.06%-17.48%respectively;under the condition of real sewage,relative error ranges of the simulation values and predicted values for COD,ammonia nitrogen,TN,TP,PHB,nitrate in effluent of each reaction stage（unit）are 6.47%-16.23%、12.08%-16.28%、5.04%-12.62%、10.23%-13.17%、7.93%-13.17%、4.90%-39.06%respectively.On the whole,the relative error of predicted and the measured values for TP is higher due to the smaller base of the index.The study found that in anaerobic stage and anoxic stage the existence of ordinary denitrification may increase the prediction error of COD,nitrate and total nitrogen;In addition,neglect of the role of anaerobic ammonium oxidation leads to the prediction error increases of ammonia nitrogen concentration in effluent of anaerobic period.As a result,ordinary denitrification process and the ammonification process in anaerobic period should be focus on and included in the model as to further improve the prediction accuracy of the model.