强化混凝技术处理二沉池出水的正交试验研究

Orthogonal Experiment on Enhanced Coagulation Process for Advanced Treatment of Secondary Settling Tank Effluent

某城市污水处理厂二沉池出水拟采用强化混凝技术进行深度处理后用作邻近发电厂的冷却用水。为了指导生产运行,采用正交试验对强化混凝技术的主要影响因素进行了研究。结果表明:影响因素的主次顺序为助凝剂投加量>搅拌转速>接触污泥浓度>絮凝阶段pH。强化混凝技术处理该二沉池出水的最佳运行工况:PAM浓度为0.3 mg/L,接触污泥浓度为2.5 g/L,搅拌转速为80 r/min,pH为6.0。在最佳运行工况下,浊度由10.0 NTU降至0.5 NTU以下,TP浓度由1.5mg/L左右降至1.0 mg/L以下,最低可达0.2 mg/L,优于GB/T 19923—2005《城市污水再生利用工业用水水质》的相关要求。

The effluent of secondary settling tank of a wastewater treatment plant（ WWTP） were suggested to be further treated by enhanced coagulation process,and used as cooling water of a power plant. To guide this operation,the orthogonal experiment was performed to study the main factors of enhanced coagulation process. The results showed that the order of influencing factors was coagulant aid dosage rotation speed contact sludge concentration pH at the stage of flocculation. The optimum parameters of the enhanced coagulation process were 0. 3 mg/L coagulant aid（ PAM）,2. 5 g/L contact sludge,80 r/min rotation speed for flocculation and pH 6. 0.Under the optimum parameters,the turbidity of WWTP effluent was decreased from 10. 0 NTU to below 0. 5 NTU,and TP concentration was decreased from about 1. 5 mg/L to below 1. 0 mg/L（the lowest was 0. 2 mg/L）,which were better than the requirements in The Reuse of Urban Recycling Water- Water quality standard for industrial uses（GB/T 19923-2005）.