以模拟生活污水为原水,在室温下用一体式膜生物反应器研究了蛋白质、多糖、蛋白质与多糖含量比(P/C)及胞外聚合物(EPS)总量对活性污泥絮凝沉降性的影响,建立了各影响因素与浊度和容积指数(SVI)的二项式非线性回归方程,并分析了各组元与絮凝沉降性能的作用机理.结果表明,EPS含量增大使活性污泥的絮凝沉降性能明显变差,与浊度和SVI的非线性相关系数(R^2)分别为0.683和0.785;蛋白质和多糖含量增大导致浊度和SVI均呈增长趋势,活性污泥的絮凝沉降性能降低;P/C增大仅降低了活性污泥的絮凝性能.结合DLVO理论分析认为,EPS及其组分对活性污泥絮凝沉降的作用机理是长程范德华引力和双电层重叠时静电斥力相互叠加后最终表现为引力的结果.
The effects of concentrations of protein and polysaccharide, mass ratio of protein to polysaccharide (P/C) and total quantity of EPS on flocculation-sedimentation were studied using an integrated membrane biological reactor (IMBR) during domestic wastewater treatment at room temperature. The relationships between influential factors and turbidity as well as sludge volume index (SVI) were established by binomial nonlinear regression equations, and the corresponding flocculation-sedimentation mechanism was analyzed. The results show that increasing the concentration of EPS worsens the flocculation and sedimentation with the higher nonlinear related coefficient (R^2) being 0.683 and 0.785, respectively. With the increase of concentrations of protein and polysaccharide, both turbidity and SVI exhibit ascending tendency, demonstrating the depressed flocculation-sedimentation. The turbidity decreases while SVI displays a relative steady with increasing of P/C. And the polysaccharide has a greater effect on flocculation-sedimentation than protein. Based on the DLVO theory, the functions of EPS and its constitutes were analyzed. It is explained that the flocculation-sedimentation mechanism originates from the competitive result between long range van der Waals force and double-layer repulsion.