孟加拉国大型水厂加氯加药系统设计实例

Design Case of Chlorination and Dosing System in a Large-Scale WTP in Bangladesh

孟加拉国PADMA供水工程设计规模为4.5×10^(5)m^(3)/d,原水取自Padma河,采用高效澄清池+V型滤池的核心工艺。针对原水水质雨季浑浊度高(最高为541NTU)、含砂量大(最大为2.43kg/m^(3))、浑浊度变化大的特点,在高效澄清池前投加混凝剂硫酸铝(平均投加量为30mg/L)絮凝剂阴离子型聚丙烯酰胺(平均投加量为0.2mg/L),在进水前端投加石灰乳调节进水pH来提高絮凝效果,为强化混凝效果增设后混凝投加点。水厂实际运行效果表明,高效澄清池的出水浑浊度小于0.5NTU,出厂水浑浊度小于0.2NTU。文章对水厂液氯投加系统、加药系统的设计进行了系统介绍,以期为海外类似供水工程提供设计经验。

The design scale of PADMA water project in Bangladesh is 4.5x105 m/d,the raw water is taken from Padma River,and the core process of high-efficiency clarifier+V filter is adopted.In view of the characteristics of high turbidity(maximum is 541 NTU),high sand content(maximum is 2.43 kg/m),and wide variation of turbidity,coagulant aluminum sulfate(average dosage is 30 mg/L)and flocculant anionic polyacrylamide(average dosage is O.2 mg/L)are added at the front of high-efficiency clarifier,lime milk is added at the front of the influent to adjust the pH of the influent,and some adding points in post coagulation was set to strengthen the coagulation effect.The actual operation effect of the water treatment plant(WTP)indicated that,the turbidity of the outflow of the high-efficiency clarifier is less than 0.5 NTU,and the turbidity of the finished water is less than 0.2 NTU.This article systematically introduces the design of the liquid chlorine dosing system and the agent dosing system in the WTP,in order to provide design experience for similar overseas water supply projects.