| A2N denitrifying phosphorus process has solved the competition between phosphorus and nitrogen removal due to the characteristics of the double using of carbon,and the process has great potential on nitrogen and phosphorus removal under the shortage of carbon.As known,mathematical model of a water treatment process can assist the research,design,and control of the process.So it is of practical and theoretical significance to establish the whole A2N process mathematic model.In this study,a series of reduce order dynamic model of the A2N main reaction process was developed,which is based on simplified mechianism model and basic dynamic models for the nitrogen and phosphorus bio-removal.On the basis of those reduced order dynamic models,the model of whole A2N process(a typical denitrifying phosphrorus removal process)is constructed.The whole A2N process model could used to simulate the pollutants concentration of each unit of the process.As the same time,the experimental data of the process operating was obtained under different working conditions in the real urban sewage.Then the whole A2N process model was verified by experimental data.The simulation results show that the model has more accurate prediction.The research results of this project mainly include the following aspects:The reduced order dynamic models of the A2N system were precondition of the whole A2N process model.All dynamic parameters and stoichiometric parameters were estimated through static test data.In this paper,the dynamical parameters should be consisted of kCOD-y,KCOD-N,KNO-N,bN,YO-N,KPHB-q,klim-q,kPHB-H,kPP-H,kCOD-H,kNO-H,bzr-H,YO-H,and the stoichiometric parameters are include v(P.COD)-y,v(P,PHB)-y,v(PHB,PP)-q,v(PHB,NO)-q,v(PHB,PP)-H.It was important that all estimated parameters are the basis of the whole A2N process model applicated.(1)The main model parameters of denitrification and phosphorus removal process were obtained through static experiment.The dynamic and stoichiometric parameters were estimated by the material balance equation under steady state conditions.Under different temperature conditions,the simplified kinetic model parameters were estimated by Arrhenius model,and the stoichiometric parameters were estimated by the test data of phosphorus release and phosphorus removal.(2)The unidimensional settling model was built based on law of conservation of mass and the Takacs sinking model,and which could be applied to calculate he sludge concentration at the bottom of sedimentation tank.By using MATLAB ode45 command,the variation rule of sludge concentration in sedimentation tank could be well fitted through the established mathematical model of sedimentation tank.(3)In order to obtain the basic data of model parameter estimation and model validation,the A2N test device was constructed and operated continuously.The results showed that the best operating conditions were HRT of anaerobic,nitrification,anoxic and re-aeration reaction units was 3h,6.5h,4.5h and 1.5h respectively,Reflux ratio R1,R2 all is 28%?32%,temperature was 19?22? in the steady state stage of the A2N process system.Under this condition,the removal efficiency of denitrifying phosphorus removal was simulated with the test results of A2N process operating.It was shown that the whole A2N process model could be applied to simulate the concentration of measurable coponents of each unit and had a better predictive.The elative error range between the simulated value and the measured value of COD,PHB,total phosphorus,ammonia nitrogen,nitrate,total nitrogen were:6.16%?11.59%?8.64%?11.30%?1.73%?13.01%?7.18%?11.21%?6.42%?16.42%?6.52%?14.06%.(4)The whole process mathematical model of A2N process is constructed by using the principle of material balance,which mainly includes the material balance equations of COD,PHB,total phosphorus,ammonia nitrogen,nitrate and total nitrogen components of each reaction unit of A2N system,based on the simplified kinetic model,metrological relationship and one-dimensional sedimentation tank model of the main reaction process of A2N system.In this study,three different influencing factors,which included HRT,reflux ratio and temperature,were taken into consideration.During the steady phase of the A2N process in continuous-flow,the experimental results were verified based on the whole A2N process model.It was confirmed that the simulation values could be consistent with measured values,and the concentration change can be simulated accurately.Under the condition that the total hydraulic residence time of A2N was 15.5h,12.3h and 10.3h,the elative error range between the simulated value and the measured value of components were that COD was 4.28%?12.64%,PHB was 6.34%?11.30%,TP was 1.73%?13.01%,ammonia nitrogen was 3.57%?11.43%,nitrate was3.91%?16.42%,TN was3.99%?14.06%.Under different reflux ratios,R1 and R2 had the same range with the average value of 20%,30%and 40%,and the elative error range between the simulated value and the measured value of components were that COD was 3.8%?11.59%,PHB was 3.99%?14.14%,TP was 1.73%?13.15%,ammonia nitrogen was 3.84%?11.21%,nitrate was 2.03%?16.42%,TN was 3.77%?14.06%.The different temperature was set to 5?,20? and 30? nd the elative error range between the simulated value and the measured value of components were that COD was 3.13%?11.59%,PHB was 4.91%?12.94%,TP was 1.73%?16.16%,ammonia nitrogen was 2.36%?11.21%,nitrate was 2.16%?16.42%,TN was 2.37%?14.06%.The error of the model,the simulation value and experiment concentration,mainly includes the model prediction error and test error.And due to the relative errors of the measured components were in a low range,the application of the whole A2N process model was more accurate and reasonable. |
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