污水处理生物絮体絮凝沉淀机理分析的综述

通过介绍胞外聚合物(EPS)架桥、DLVO理论和疏水作用力3种最具代表性的理论体系,阐述了生物絮体絮凝沉淀过程、影响因素以及有待解决的问题.分析结果表明:生物絮体分泌的EPS所含蛋白质含量越少,其絮体沉淀效果越好;而疏水作用力却随EPS中蛋白质增加而加强,疏水作用力较大生物絮体絮凝能力较好,疏水作用力同时受到表面电荷的影响.此外,DLVO理论解决了EPS架桥无法解释的抗絮凝反应问题,离子强度在一定范围内越大,则絮体絮凝能力越好.

Review of Mechanism of Bioflocculation and Settleability of Activated Sludge Bioflocs

Bioflocculation of activated sludge is crucial to overall performance and efficiency of the treatment process as well as the settleability. The bindings between flocs are due to the intermolecular interactions, which can be mainly categorized into 3 interdependent and interactional types including bridging of extracellular polymeric substance (EPS), DLVO type interactions and hydrophobic interactions. Flocs and EPS carry negative charges and zeta potentials that not only produce the electrostatic interactions but create bridges among cells by means of divalent and trivalent cations. EPS contains more protein and carbohydrate than any other substances, the low concentration of which is believed to correlate with good settleability but poorly hydrophobic interactions. Moreover, low hydrophobicity which is also affected by surface charge, is associated with poor flocculation. Also high ionic strength contributes to good performance of bioflocculation. The goal of this study is to gain a comprehensive insight into sludge floc characteristics and to identify the key factors which determine the solid liquid separation properties of activated sludge.