城市污水的混凝处理及混凝污泥厌氧消化研究

采用聚合氯化铝与有机高分子絮凝剂复合投加的方法,对上海市闵行污水处理厂曝气沉砂池出水进行一级强化处理,研究了其对浊度、COD的去除效果,确定最佳投药量。在确定最佳投药量后,对混凝所产生污泥进行厌氧消化的可行性研究。结果表明:(1)有机絮凝剂与聚合氯化铝复合投加的强化效果明显优于单独投加聚合氯化铝;同时,聚合氯化铝与阳离子型有机絮凝剂复合投加的效果要优于阴离子型,并且可以进一步降低聚合氯化铝的投加量;使用聚合氯化铝与两性型有机絮凝剂复合投加也取得了较为满意的效果,与使用阳离子型有机絮凝剂的效果接近。(2)综合考虑COD、浊度和药剂投加量,当聚合氯化铝投量为30mg/L、阳离子型有机絮凝剂KP1205E投加量为2mg/L时,取得比较理想的效果。(3)被处理水的水质变化对化学一级强化的处理效果有很大影响,被处理水中溶解性的有机物组分越高,处理效果相应越差。(4)采用厌氧消化对混凝污泥进行处理,在投配比为5%时,单位VSS的产气量最大,达到0.76L/g,污泥的可消化性较好。

A Research on Chemically Enhanced Primary Treatment of Sewage and Anaerobic Digestion of Coagulated Sludge

Chemically enhanced primary treatment (CEPT) was carried out to treat municipal sewage of Minhang wastewater treatment plant by joint dosage of polymeric aluminium chloride with organic polymer flocculant. The removals for turbidity and COD were investigated to find out their optimal doses. Then the feasibility of anaerobic digestion for coagulated sludge was studied. It has concluded that (a) a combination dosage of organic flocculant with polymeric aluminium chloride was more effective than an only dose of the latter; cationic organic flocculant showed superior to anionic one and meanwhile conducive to dosing further less polymeric aluminium chloride; and a combination with amphoteric organic flocculant also showed satisfactory effect similar to that of using cationic flocculant; (b) to balance the reduction in COD and turbidity as well as the dosage, a fairly satisfactory effect could be attained by dosing 30mg/L of polymeric aluminium chloride plus 2mg/L of cationic organic flocculant KP1205E; (c) the strength of sewage showed a great influence on the efficiency of CEPT, i. e., the more soluble organic contents in the sewage, the less treatment efficiency accordingly; (d) in anaerobic digestion of coagulated sludge, a 5% dose could attain the maximum gas production perunit VSS reaching 0.76L/g, and the sludge was rather well digestible.