影响亚硝化过程和硝化过程因素的动力学模型分析

Mathematical kinetics model evaluation of factors effect on nitritification and nitrafication process

用数学模型模拟了1L初始氨氮浓度60mg·L-1且无其它氮源的污水完全混合批式硝化过程,并分别计算了溶解氧、温度、微生物群落对硝化过程的影响.模拟结果表明,DO浓度降低时各物质转化速度也降低,DO=0.5mg·L-1和氨氧化细菌占优势时NO2--N的转化率可高于50%,因而低浓度溶解氧有利于NO2--N积累;不同温度的氨氧化细菌和亚硝酸氧化细菌代谢速度不同,温度升高对氨氧化细菌的促进作用更大,亚硝酸盐氮浓度最大值随温度升高而增大,温度高于30℃有利于NO2--N的积累;此外硝化动力学方程对底物最大比氧化速率的灵敏度要高于亲和常数的灵敏度,但二者均低于微生物构成对模拟结果的影响,溶解氧和温度对硝化过程的影响也均不如微生物构成显著,因此要确保亚硝化过程的实现,必须保持系统中氨氧化细菌占优势.

The effects of dissolved oxygen （DO） , temperature, microbial community on nitritification process were evaluated by mathematical models in a 1 liter well mixed batch nitrification system with the initial ammonia nitrogen of 60 mg·L^-1 and no any other nitrogen source. Based on the evaluation results, the transformation rates of the involved substance decrease with decrease of DO concentration. When ammonia oxidizing bacteria are dominant in the microorganism community, the conversion rate of ammonia to nitrite can excess 50% at DO = 0.5 mg·L^-1 , which implies that lower DO concentration is favorable for the nitritfication process. Temperature influences the metabolism rate of ammonia - oxidizing bacteria and nitrite - oxidizing bacteria to different degree. The maximum concentration of nitrite increases with higher temperature due to the more improvement of temperature to nitritefication than to nitratification. Temperature above 30℃ will be suitable for nitrite accumulation. The affinity constant is less sensitive impact than the maximum specific substrate oxidation rate on the nitrification kinetic model analysis, whereas evaluation results is more likely affected by the composition of microbial community than model parameters. Similarly, comparing dissolved oxygen and temperature with microbial community, the same conclusion can be drawn. This means that ammonia - oxidizing bacteria should be kept dominant to assure nitritification process.