低负荷氧化沟系统中EPS与活性污泥沉降性能的关系

污泥膨胀是氧化沟系统中常见的运行问题,为寻求有效的针对性污泥膨胀的控制措施,需要首先明确污泥膨胀发生的机理.因此,在实验室模拟氧化沟处理系统中,采用以可溶性淀粉为碳源的模拟生活污水,探索了系统内污泥EPS的变化及其与污泥膨胀的关系.试验结果显示,在低负荷氧化沟中,污泥出现丝状膨胀,污泥中EPS含量及EPS中蛋白质含量与污泥的沉降性能(SVI)之间呈现出明显的负线性关系,但EPS中糖的含量与污泥的SVI之间无明显的线性关系.适当提高污泥负荷,污泥的EPS含量增加、沉降性能改善.研究认为,在低负荷运行的系统且缺乏细菌可快速容易降解碳源的条件下出现的污泥中EPS减少,并非是氧化沟污泥发生丝状膨胀的致因,丝状菌的优势繁殖才是根本原因.不能通过控制EPS来影响氧化沟低负荷下的污泥丝状膨胀.

Relationship between EPS and activated sludge sedimentation performance in the low-load oxidation ditch system

Sludge bulking is a common problem in operation of oxidization ditch system. To illuminate the mechanism of the sludge bulking, a lab-scale intermittent aeration and continuous flow oxidation ditch system was established and applied to study the relationship between EPS of sludge and its sedimentation performance under different operating conditions. Soluble starch was used as the sole carbon source. The results showed that filamentous bulking of the sludge in the system occurred at low load. Both content of EPS and protein amount in the EPS had a distinct negative linear relationship with SVI of the sludge, but the carbohydrate content did not. The content of EPS rose after sludge load increased along with improvement of sludge sedimentation performance. We considered that the growth of filamentous bacterium was the key factor for the sludge bulking in the system, rather than the decrease of EPS in the sludge under low load condition and the scarcity of readily biodegradable carbon source for bacterium in the sludge. It was believed that affecting the EPS content of the activated sludge could not result in the filamentous sludge bulking under low sludge load condition in the OD system.