Study On Sequencing Batch Reactor Nitros Ation Start-up And Control Factor Of Urban Domestic Wastewater

As one of the main factors causing eutrophication, the effect of nitrogen on the environmentalpollution has been paid more and more attention. In recent decades, on the basis of the traditional biologicaldenitrification, domestic and foreign researchers has developed new economical，efficient and energysavingtechnologies. However, as the key step of these new technologies, the nitrosation process is hard to realize,and therefore it’s difficult to maintain a steady process under normal conditions.In this research, the SBR reactor was studied at the temperature around30℃with the pH range7.6～7.9, and started successfully in the conditions of low level of DO and continuous aeration. After thesuccessful start of the nitrosated reactor, the effect of nitrosation in different temperatures were investigated,and the kinetic equation of degradation rate of ammonia nitrogen was established. The results in this studywere as follows:1)The removal rate of ammonia nitrogen and nitrite nitrogen were at least80%and90%, respectivelyafter32cycles of continuous operation, at the temperature around30℃with the pH around7.6and DOabout0.3mg/L. Therefore, the nitrosation start-up process of municipal domestic waste water in lowammonia nitrogen concentration was achieved.2)The jump of the DO and the turning point of the ORP and pH, which could be used as the end-pointcontrolling indicators to judge the nitrosation reaction，were obtained after the monitoring of the typicalcycle of DO, ORP and pH. It was found that the accumulation of the nitrite nitrogen could achievemaximum degree when the aeration time was controlled within30minutes after the ends of the nitrosation.3) The steady nitrosation process could be obtained through lowering the DO and C/N, whileincreasing the pH. The average removal rate of the ammonia nitrogen was around87%, while theaccumulation rate of the nitrite was around92%.4) It was found that the temperature was one of the main factors that affected nitrosation. In theappropriate temperature range, the nitrosation rate was faster and the nitrite accumulation was more significant with a higher temperature of the system. And as the temperature got lower, the removal rate ofammonia nitrogen and the accumulation rate of the nitrite decreased significantly. It was concluded that theaccumulation of the nitrite could be easy to achieve in a higher temperature.5) The kinetic process of the nitrosation was analyzed on the steady nitrosation experiment basis, andthe degradation kinetic equation of the nitrosation of the ammonia nitrogen was obtained and verified withexperimental data. The results showed that the kinetic parameters of the high concentration conformed toreality better than those of the lower. Based on the data of the experiment, the kinetic parameters and theregression coefficients of the nitrosation were obtained in the differential method and the least squaremethod of linear regression. The relevant parameters were as follows: Ks=0.69mg/L,vmax=0.024h^-1, R²=0.904。...