Dynamic Simulation For The Wastewater Treatment Process Of Simultaneous Nitrogen And Phosphorus Removal Based On ASM2D

Simultaneous nitrification and denitrification phosphorus removal technology?SNDPR?is a synchronous nitrogen and phosphorus removal technology that has attracted much attention with the advantages of low energy consumption,low carbon source consumption,low sludge output,and low cost.However,even though the SNDPR technology has achieved good results in laboratory research,the colony ecology in the SNDPR system is complex,difficult to control in actual reactor,and requires high maintenance.Therefore,it is urgent to solve the overall control of the process to put it into actual production.In addition,studies have shown that large amounts of N₂O are produced during the SNDPR process.Therefore,the establishment of a model containing the N₂O prediction model for the SNDPR process has great significance to the development of the SNDPR process in the simulation technology,mathematical model of sewage treatment,the reduction of greenhouse gases emissions and,the design and operation of the actual engineering application in the future.In this study,AQUASIM 2.0 was used to build the model,and the experimental data of the laboratory A/OLA-SNDPR was used as the actual measured value to realize the parameter correction and dynamic simulation test of the extended model.The main research results are as follows:?1?This paper considered the role and reaction process of nitroxyl?NOH?in the incomplete oxidation of hydroxylamine to produce N₂O;it considered the denitrification of AOB(X_AOB),incomplete oxidation of hydroxylamine?NOH pathway?,denitrification of heterotrophic bacteria?X_H?and phosphorus accumulating bacteria(X_PAO)together and used it in the simulation prediction of carbon,nitrogen,phosphorus and greenhouse gas N₂O in A/OLA-SNDPR system.?2?This paper found that X_AOBdenitrification was the most important process of N₂O formation in the A/OLA-SNDPR process through the combination of experiments and models and another main pathway was the X_Hdenitrification pathway.The analysis of parameter sensitivity found that the parameters related to the metabolism of phosphorus accumulating bacteria in the A/OLA-SNDPR system had the highest sensitivity to N₂O,and had a negative correlation effect on N₂O output.?3?The results showed that due to the large differences in the microbial structure in the SNDPR system,the values of some parameters were different from other processes.The calibration value was 0.14 lower than the literature value 0.145.The?_NO,Hcalibration value?4?Through the analysis of phosphorus load impact experiment and model simulation results,we found that N₂O emissions can be reduced by enhancing the advantages of X_PAOover X_H,thereby enhancing the competitiveness of phosphorus accumulating bacteria against denitrifying electron acceptors;The increase of the influent phosphorus concentration would not affect the metabolic process of nitrifying bacteria.The decrease of nitrate concentration was related to the metabolism of phosphorus-accumulating bacteria and heterotrophic bacteria.And in the A/OLA-SNDPR system,the total nitrogen in the effluent was mainly nitrate nitrogen,and the low carbon to phosphorus ratio would enhance the activity of the phosphorus-accumulating bacteria,thereby reducing the effluent phosphorus concentration and nitrate concentration in the oxygen-limited reactor.