Optimisation for Enriching Ammonium Oxidizing Bacteria in Membrane Partial Nitrification Reactor: Mathematical Simulation

Wei-Kang Qi, Shi-Long He, Yan-Long Zhang, Jie Xu, X. Jin Yang, Yu-You Li



Partial nitrification is thought to be a more economical process for the removal of high ammonia concentration from wastewater. In order to promote nitrite accumulation, the key step is to take measures to enrich ammonia oxidizing bacteria (AOB) and suppress nitrite oxidizing bacteria (NOB) in a membrane biological reactor (MBR). Using a mathematical model, the effects of different operational parameters, such as dissolved oxygen (DO), sludge retention time (SRT) and temperature et al., have been evaluated in terms of the nitrification process. The results indicated that DO could be used as an independent control factor to achieve partial nitrification. High temperature and low SRT were shown to bead vantageous for AOB accumulation, and a low SRT was shown to decrease the sensitivity of partial nitrification to variations in DO concentration. The successful start-up partial nitrification process is more stable with a combination of various parameters, such as DO and influent concentration. Low temperature causes ammonia accumulation due to the decreased metabolic activity of AOB. By increasing DO concentration, it is possible to maintain a stable system despite seasonal temperature changes. It was clarified that a suitable combination of DO and other parameters is crucial achieving a partial nitrification process.