活性污泥与消化污泥的脱水特性及粒径分布

Dewaterability and Particle Size Distribution of Activated and Digestion Sludge

对活性污泥和消化污泥的脱水特性和粒径分布进行了研究,分析了2种污泥胞外聚合物(EPS)含量的差异以及生物相的变化特征和机理.结果表明,表征脱水性能好坏的毛细吸收时间(CST),新鲜活性污泥为9.84 s,消化污泥增加到607.5 s,消化污泥固体颗粒从悬浮液分离所需的时间变长,脱水性能变差.其原因一方面是消化过程使EPS中蛋白质和多糖降解,另一方面是大大降低了消化污泥中原生动物数量,减少了促进微生物凝聚的EPS物质向污泥中的释放.消化污泥EPS含量为123mg/g(以干污泥计,下同),比EPS含量为540 mg/g的活性污泥减少了77%.EPS的降解使较大的污泥颗粒分解成较小的污泥颗粒,活性污泥占体积最大的颗粒粒径是133μm,消化污泥下降到44.6μm,活性污泥的平均粒径是132.6μm,消化污泥仅为70.48μm,结果导致消化污泥脱水性能变差.

The dewaterability and particle size distribution of activated and digestion sludge were studied. Meanwhile, the related mechanism was explored through analyzing the extracellular polymeric substances （EPS） content and microbe characteristic of activated and digestion sludge. The dewaterability was evaluated using the capillary suction time （CST） and settling property. The CST of activated sludge and digestion sludge are 9.84 s and 607.5 s, respectively. The settling time of the solids of digestion sludge is longer than that of activated sludge. The major reason of poor dewaterability of digestion sludge is the degradation of carbohydrate and protein parts of EPS. In addition, the quantity of protozoan in digestion sludge is less than that of activated sludge, resulting in reducing the excretion of certain matters benefiting the agglomeration between microbes. The EPS content of digestion sludge is 123 mg/g, which was 77% less than that of activated sludge. The degradation of EPS during the digestion process leads to the smaller particle size of digested sludge, and then the poorer dewaterability. The particle size that occupied maximum volume in activated sludge is 133 μm, while it is 44.6 μm in digestion sludge. The mean particle size of activated sludge is 132.6 μm which is larger than that of digestion sludge （70.48 μm）.