The Study On Short-cut Nitrification Startup In The Intermittently Aerated Membrane Bioreactor And It's Nitrogen-removal Performance

In recent years, eutrophication is the main environmental problem in South China and it is getting worse. The exceeded N, P emission is the main factor that causes the eutrophication. In addition, a number of strict constraints are introduced in recent years on the N, P emission. But the conventional wastewater treatment process at this stage can not be a better solution with low C / N removal, so for the low C / N wastewater nitrogen removal in southern town of China, this paper attempts to combined shortcut nitrification with IAMBR to find a suitable operating conditions to enable stable and efficient nitrogen removal under the low C / N condition.The experimental part includes: The fluent analysis of the main reactor; Shortcut nitrification system startup process studies and IAMBR operation parameters adjustment and working-mode analysis. The conclusions are these:(1) The following conclusion are obtained by the tracer test analysis: when the reactor were stirred at low aeration strength and a separate auxiliary stirring volume of the reactor under the conditions of utilization was 94.33% and 91.33%, so the reactor can be considered as an ideal completely mixed reactor in both working conditions.(2) In the shortcut nitrification start-up process, through the system environmental factors (DO, pH, FA, temperature) adjustment it could be conclude that in shortcut nitrification system start-up stage, the descending order of the influence to the nitrate accumulation is temperature, pH (FA) and DO, and the Pearson correlation coefficient between these factors and the nitrate accumulation are 0.835,0.758,0.649 respectively.(3) In the stable nitrosation stage, through the analysis the effect of oxygen, pH, alkalinity on system stability and nitrosation rate , the follows could be concluded : when oxygen ascends from 60L/h ascending to 100L/h, the system nitrosation rate rose from 7.39×10^-4mgNH3-N/mgMLSS·h to 2.29×10^-3mgNH3-N /mgMLSS·h; When water alkalinity rise to 1438mg/L, the system nitrosation rate dropped to 6.84×10^-4mgNH₃^-N / mgMLSS·h; pH impact on the system is not obvious, and when water pH = 8 or so, the system has the largest nitrosation rate.(4) Through adjusting the IAMBR process parameters (A/O=1h/3h, 2h/2h and 2h/1h, aeration strength = 100L/h, 140L/h and 160L/h) after the shortcut nitrification and denitrification system startup, the system get the largest TN removal(61%) on the condition of that A/O = 2h/1h and aeration strength is 100L/h, the COD and NH3-N removal rate are 79% and 83% respectively, when the aeration rate were increased to 140L / h and 160L / h, the average removal rates of COD, NH₃-N, TN were 81% and 85%; 86% and 93%,60% and 55%. By establishing NH3 - N degradation model of IAMBR cycle, the result shows that A/O rate has some influence on NH3-N degration constant k.(5) The continuous flow experiment in IAMBR indicated that denitrifying bacteria activity will gradually adapt to the environment, and the NO₂^--N accumulation in the effluent gradually reduce (from 80% dropped to about 40 %).