超声及碱处理促进剩余污泥水解的试验研究

Ultrasonic Pretreatment and Alkaline Treatment for Promoting Hydrolysis of Excess Activated Sludge

剩余污泥水解是解决污水处理厂生物脱氮除磷的碳源不足和实现污泥资源化的重要途径。采用3个平行反应器,在35℃、厌氧条件下研究了剩余污泥以及经过超声预处理和碱处理(pH=10±0.1)的剩余污泥的水解过程。结果表明:超声预处理以及碱处理均能促进剩余污泥的水解,它们对污泥的平均比降解速率较原污泥可分别提高39.4%和93.9%,SCOD的平均溶出速率可分别提高92.9%和150.4%。另外,碱处理后水解对剩余污泥的降解比超声预处理的更快、更彻底。根据污泥比降解速率、SCOD溶出速率以及营养物释放速率大小,可认为水解过程分多阶段进行,其中污泥比降解和SCOD溶出速率在第Ⅰ阶段(0～2d)最大,磷释放速率在第Ⅱ阶段(4～6d)最大。透射电镜扫描结果表明:剩余污泥水解的次序为EPS、胞内物质、细胞壁。

The hydrolysis of excess activated sludge is an important way to solve the deficiency of carbon source during removal of nitrogen and phosphorous and to use municipal sludge as resource. Three batch reactors （without treatment, ultrasonic pretreatment, alkaline treatment with pH of 10 ±0. 1 ） were adopted under anaerobic condition at 35 % in this experiment to compare the characteristics of hydrolysis process. The results show that both ultrasonic pretreatment and alkaline treatment can improve the hydrolysis of excess activated sludge, enhancing the average specific rate of sludge degradation by 39.4% and 93.9% respectively, and increasing the average dissolution rate of SCOD by 92.9% and 150.4% respectively when compared with natural sample. The efficiency of alkaline treatment is better than that of ultrasonic pretreatment. The hydrolysis process can be divided into several phases according to the specific rate of degradation, the dissolution rate of SCOD and the releasing rate of nutrients from the sludge. Among these phases, the specific rate of degradation and the dissolution rate of SCOD are highest at the first phase （0 to 2 d）, and the phosphorous release rate is highest at the second phase （4 to 6 d）. Photos from transmission electron microscope show that the sequence of sludge hydrolysis should be extracellular polymeric substances （EPS）, intracellular substances and cell wall.