Modeling The Partial Nitrification Process In BAF By Extended ASM1-2N Model Incorporating C/N Ratio

Shortcut nitrification and denitrification as a new kind of nitrogen removal theory,which can save 25% of oxygen consumption compared to the conventional nitrification-denitrification process by controlling the nitrification process directly in nitrite and then reduced to N2.At present,it is not very rich in the design and operation of the shortcut biological nitrogen biofilter,and numerical simulation of the nitrogen removal process in biofilter can provide some practical help for the actual operation.In this paper,the biological aerated filter as the experimental object,the effect of C/N ratio on the shortcut biological nitrogen removal was studied,and a one-dimensional nitrification-diffusion model with C/N control factor was established,and the shortcut biological nitrogen removal in two kinds of aerated biofilter was simulated by using the model.Specifically,the following work has been undertaken:(1)Taking ASM1-2N two-step nitrification-denitrification model as the basic model,the ASM1-2N Standard simplification model suitable for short course nitrification process and the Monod and logistic model of adding C/N ratio were established.(2)Using AQUASIM software to analyze the sensitivity of ASM1-2N-standard and extended model,combined with experimental data,the common parameters of three model effect effluent water quality were found: activated carbon column((7?(4??(4),and ceramsite column((7???).The model was checked by parameter estimation,and the simulated value of the model is in agreement with the measured value in a larger range,which shows that the model can better respond to various reaction processes in biological aerated filter process.Through the comparison of three models,it is found that the logistic model of adding C/N ratio is optimal for the steady state simulation.(3)The 23-Day continuous Influent simulation value and experimental data were compared.It is found that the standard model has the best simulation results for cod,and the logistic model is optimal for TN.The model can well reflect the steady state operation in biological aerated filter.(4)Through the simulation of different influent flow,it is found that the concentration of COD and NH4--N along the BAF decreases with the decrease of influent flow,and the concentration of NO2--N and NO3--N increases with the decrease of influent flow.The smaller the flow rate,the slower the flow velocity in the reactor,the more obvious the shortcut nitrification effect in the reactor.