低碳氮比条件对活性污泥粒径分布的影响

Effects of Low COD/N Ratios on Flocs Size Distribution of Activated Sludge

活性污泥絮体的微环境被认为是同步硝化反硝化反应（SND）发生的机理之一,而适宜的絮体尺寸有利于SND的发生。本文以人工调配的低碳氮比污水为研究对象,采用SBR反应器,研究了其对活性污泥絮体尺寸分布的影响,分析了絮体尺寸分布与SND效率之间的关系。低COD/N条件（1.05、1.98、2.95和3.94）分别通过控制进水水质组成实现。结果表明,大于10μm的絮体大小分布符合对数正态分布函数的粒度分布。整体看来,低COD/N 比进水与污泥絮体粒径分布没有显著的相关性。但是,在COD/N 1.98~3.94范围内,絮体尺寸随着COD/N增加从117.04μm升高到181.35μm；相应地,SND效率从40.84%上升至94.72%。与COD/N 比1.05 相比,絮体粒径的分布更加的稳定,有更小的标准偏差,具有更加一致的log-normal 分布函数形状。

The microenvironment of activated sludge flocs is considered to be one of the mechanisms of simultaneous nitrification and denitrification （SND）, and the appropriate size is favorable for the occurrence of SND. The aim of this paper is to investigate the effect of the influent of low COD/N ratios on flocs size distribution of activated sludge in the sequencing batch reactors. The relationship between the focs size distribution and the efficiency of the SND was analyzed. The study was performed by controlling the influent quality composition of COD/N ratios （1.05、1.98、2.95 and 3.94）. Results show that the size distribution of flocs larger than about 10 μm fitted well to log-normal distribution functions. As a whole, there was no significant correlation between the low COD/N ratios and the flocs size distribution. However, in the range of COD/N ratios 1.98~3.94, the size of the activated sludge flocs increased from 117.04μm to 181.35μm with the rising of COD/N, and the SND efficiency increased from 40.84% to 94.72%. Compared with the COD/N 1.05, the flocs size distribution is more stable and has a smaller standard deviation, which has a more uniform log-normal distribution function.