酸-低热联合处理对剩余污泥脱水性能的影响

为有效降低城市污水处理厂剩余污泥含水率，通过酸-低热（温度 < 100℃）联合处理污泥，探索该方法对污泥的脱水性能.研究不同pH、反应温度、反应时间对污泥脱水性能的影响，并对污泥上清液中SCOD、蛋白质、多糖的浓度以及污泥Zeta电位和污泥形貌进行分析，初步探讨其脱水的作用机理.结果表明:①酸-低热联合处理污泥时，污泥溶解性有机质大量释放，经过40 min反应，上清液中SCOD浓度达到925.76 mg/L，表明该方法能有效破解污泥EPS（胞外聚合物），释放内部结合水.②原污泥Zeta电位为-14.10 mV，酸-低热联合处理后降至-3.49 mV，污泥颗粒之间的静电斥力显著降低.③酸-低热联合处理有利于污泥的絮凝作用，显微镜观察处理后的污泥絮凝物大且结构紧密，污泥脱水性能得到改善.④试验获得的最佳处理条件为pH 3、温度90℃、加热时间40 min，在该条件下，污泥真空脱水初始速率可达20.67 mL/min（以80 g原泥计），泥饼真空抽滤后含水率可降至63.05%.研究显示，酸-低热联合处理可有效提高剩余污泥脱水性能，并能释放较多溶解性有机质，抽滤后污泥含水率可降至接近60%，是一种可行的低能耗污泥脱水方法. 

Effect of Acid-Heat Combined Treatment on Residual Sludge Dewatering at Low Temperature

In order to effectively reduce the water content of residual sludge in the municipal wastewater treatment plants, the performance of sludge dewatering by acid-heat (temperature < 100℃) treatment processes was evaluated. The effects of pH, temperature, and heating time on sludge dewatering were studied. Meanwhile, the mechanism of sludge dewatering was tentatively elucidated based on the soluble chemical oxygen demand (SCOD), protein and polysaccharide in the sludge supernatant, zeta potential analysis, and floc morphology of the sludge. The results showed that: (1) The SCOD of sludge supernatant increased to 925.76 mg/L after the sludge was treated by acid-heat treatment for 40 min, indicating that the extracellular polymeric substances (EPS) of sludge could be effectively broken with the release of the internal bound water. (2) The zeta potential of raw sludge was -14.10 mV, it decreased to -3.49 mV after acid-low heat treatment, and the electrostatic repulsion between sludge particles decreased significantly. (3) The combined treatment process of acidification and low temperature heating was beneficial to the flocculation of sludge since large and compact flocs were formed, suggesting that the dewatering performance of sludge was improved. (4) The optimal treatment conditions were determined as follows: pH 3, temperature 90℃ and heating time 40 min. Under such conditions, the sludge dewatering rate could reach 20.67 mL/min and the moisture content of cake was reduced to 63.05%. In conclusion, the combined treatment process can effectively improve the sludge dewatering performance and release more dissolved organic matter under low temperature heating conditions. The moisture content of the sludge can be reduced to nearly 60% after filtration, which is a feasible sludge dewatering method.