DO对SBBR工艺同步硝化反硝化的影响研究

实验研究了序批式生物膜反应器(SBBR)同步硝化反硝化生物脱氮城市污水处理工艺。试验结果表明:DO是影响SBBR工艺实现同步硝化反硝化的一个重要因素,将DO控制在2.8～4.0mg/L的范围内,可以取得较好同步硝化反硝化效果,总氮去除率可达67%以上。通过好氧反应过程中溶解氧在生物膜内反应扩散模型以及扫描电镜对生物膜的形态结构观察,分析了SBBR工艺同步硝化反硝化机理。SBBR工艺同步硝化反硝化主要是由微环境引起的,生物膜在好氧条件下能创造缺氧微环境,DO浓度直接影响生物膜内部好氧区与缺氧区比例的大小,进而影响硝化和反硝化的效果。DO浓度升高,使氧传递能力增强,使生物膜内部原来的微环境由缺氧性转为好氧性;反之DO浓度降低,生物膜内部微环境倾向于向缺氧或厌氧发展。

Effect of DO on Simultaneous Nitrification and Denitrification in Sequencing Batch Biofilm Reactor

Sequencing batch biofilm reactor(SBBR) was tested for simultaneous nitrification and denitrification(SND) for municipal wastewater.Results showed that the dissolved oxygen(DO) present in SBBR was an important factor in achieving a higher degree of SND, with TN removal efficiency above 67% at DO of 2.8～4.0mg/L.The mechanism of SND in SBBR was analyzed on the basis of DO diffusion model within biofilm and observation of scanning electron microscopy.It was found that SND in SBBR was caused by anoxic microenvironment which existed in the biofilm under aerobic conditions.DO concentration directly affected the proportion of aerobic fraction and anoxia fraction in the biofilm, which led to an effect on efficiency of nitrification and denitrification.With increase of DO concentration, the speed transfer efficiency of oxygen was enhanced to make microenvironment convert from anoxia environment to aerobic environment.Microenvironment inclined to convert from aerobic environment to anoxia or anaerobic environment with decrease of DO concentration.