有机物特性对AAO系统污泥沉降性能的影响

研究了不同进水混合型有机物组成下AAO系统中活性污泥菌群结构演替规律以及微生物胞内、胞外聚合物的变化对污泥沉降性能的影响.结果表明,当进水中有机物全部为溶解态时,污泥沉降性能最佳,污泥体积指数(sludge volume index,SVI)为70 m L·g-1,且优于进水有机物以溶解态为主(SVI=120 m L·g-1)和以颗粒态为主(SVI=280 m L·g-1)的系统.根据菌群结构分析可知Thiothrix、Chryseolinea和Trichococcus这3种菌属对污泥沉降性能的影响至关重要.其中颗粒态有机物可促进Trichococcus的生长,而溶解态有机物可促进Thiothrix和Chryseolinea的生长.此外,菌群结构的改变也对胞内及胞外聚合物的变化有重要影响,从而加剧污泥沉降性能改善或恶化的进程.较高的溶解态有机物含量可提高胞内聚合物贮存能力,并改善污泥沉降性能.同时,污泥沉降性能也与松散附着胞外聚合物(loosely bound extracellular polymeric substances,LB-EPS)中多糖、蛋白质和Zeta电位呈显著负相关关系.

Effect of Organic Characteristics on Sludge Settleability in an AAO System

The effects of different mixed organic matter ratios on sludge settleability were examined from the succession patterns of microbial community structure, and changes of microbial intracellular and extracellular polymers in the activated sludge. The experimental results showed that when organic matter was dissolved in the influent, the sludge settleability was optimal (SVI=70 mL·g^-1), which was better than that for influent water with partially dissolved organic matter (SVI=120 mL·g^-1) and particulate organic matter (SVI=280 mL·g^-1). According to the analysis of microbial community structure, Thiothrix, Chryseolinea, and Trichococcus were important in influencing the sludge settleability. Of these, particulate organic matter promoted the growth of Trichococcus, and dissolved organic matter promoted the growth of Thiothrix and Chryseolinea. In addition, changes in the bacterial community also had an important influence on the changes of intracellular and extracellular polymers, which either enhanced or impeded settleability. The higher the content of dissolved organic matter in the influent, the higher the storage of intracellular polymeric substances and, therefore, the better the sludge settleability. The sludge settleability was significantly negatively correlated with polysaccharides, proteins, and the Zeta potential in the LB-EPS.