Liao B Q, Allen D G, Droppo I G, Leppard G G, Liss S N
Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario, Canada M5S 3E5.
Water Res. 2001 Feb;35(2):339-50. doi: 10.1016/s0043-1354(00)00277-3.
The influence of sludge retention time (SRT) on the extracellular polymeric substances (EPS) and physicochemical properties (hydrophobicity and surface charge) of sludge was studied using laboratory-scale sequencing batch reactors (SBRs) fed a synthetic wastewater containing glucose and inorganic salts. Sludge surfaces were more hydrophobic (larger contact angle) and less negatively charged at higher SRTs (16 and 20 d) than at lower SRTs (4 and 9 d). The ratio of proteins to carbohydrates within the EPS of the sludges increased as the SRT increased from 4 to 12 d corresponding to the changes in the physicochemical properties of the sludge. The protein:carbohydrate ratio remained constant at SRTs of 16 and 20 d. A transition in sludge properties appeared to occur between the upper range of low- (9 d) and lower range of high-SRTs. The total EPS content, however, was independent of the SRT. A higher sludge volume index (SVI), an indication of poorer settleability or compression, was associated with a larger amount of total EPS but no significant correlation between SVI and the surface properties of sludge was observed. A more hydrophobic and less negatively charged surface corresponded to lower levels of ESS. These results indicate that it is the surface properties, hydrophobicity, surface charge and composition of EPS, of sludge, rather than the quantity of EPS, that govern bioflocculation. In contrast, the EPS content is more important in controlling the settleability of sludge.
利用实验室规模的序批式反应器（SBR），以含有葡萄糖和无机盐的合成废水为进水，研究了污泥停留时间（SRT）对污泥中胞外聚合物（EPS）及物理化学性质（疏水性和表面电荷）的影响。与较低的SRT（4天和9天）相比，在较高的SRT（16天和20天）下，污泥表面疏水性更强（接触角更大）且带负电荷更少。随着SRT从4天增加到12天，对应污泥物理化学性质的变化，污泥EPS中蛋白质与碳水化合物的比例增加。在SRT为16天和20天时，蛋白质与碳水化合物的比例保持恒定。在低SRT上限（9天）和高SRT下限之间似乎出现了污泥性质的转变。然而，EPS的总量与SRT无关。较高的污泥体积指数（SVI）表明沉降性能或压缩性较差，它与总EPS含量较高有关，但未观察到SVI与污泥表面性质之间存在显著相关性。疏水性更强且带负电荷更少的表面对应着较低水平的ESS。这些结果表明，决定生物絮凝的是污泥的表面性质、疏水性、表面电荷和EPS组成，而非EPS的量。相比之下，EPS含量在控制污泥沉降性能方面更为重要。
