饮用水水源突发性Cd(Ⅱ)污染应急处理实验研究

Experimental study on emergency treatment of the water resource contaminated by Cd(Ⅱ)

首先评估了水厂现行工艺对Cd(Ⅱ)的去除能力,然后根据饮用水水源地突发性Cd(Ⅱ)污染的特点对水中Cd(Ⅱ)的去除进行实验研究。结果表明,使用聚合氯化铝铁和水玻璃作为混凝剂和助凝剂的水厂现行工艺对Cd(Ⅱ)的最高去除率为75.0%。随pH值增大,水厂工艺对Cd(Ⅱ)的去除率会相应提高,当pH值为9.0时,Cd(Ⅱ)的去除率可达到90.0%。向原水投加碳酸钠可以改变其pH值。当碳酸钠投量为20 mg/L时,原水的pH值可由原来的7.90升高到8.97,该条件下可以同时产生氢氧化镉和碳酸镉两种沉淀颗粒,较大程度上增强了Cd(Ⅱ)的去除效果。

The given paper intends to present the results of our experimental study of an improved emergency treatment of the water resource contaminated by Cd（Ⅱ）.Based on the evaluation of Cd（II） removing efficiency by traditional water treatment process,an experimental study have been done in view of the accident contamination caused by Cd（II） to the source water.The results of the experiments show that the highest removing efficiency of Cd（II） could be made as high as 75.0% under the conditions of taking PAFC as coagulant and sodium silicate as its aids.It has also been found that the removing efficiency can be made to increase with pH value going up.When the value of pH was 9.0,the removing efficiency of Cd（Ⅱ） could reach 90.0%.In addition,it was possible for the pH value of the source water to get changed by adding sodium carbonate at a dosage of sodium carbonate of about 20.0 mg/L,that is to say,the pH value could be made to rise from 7.90 to 8.97.Under such conditions,the removing effect could also be enhanced on the condition that the cadmium carbonate and cadmium hydroxide were produced simultaneously.Thus,the experimental results indicate that the removing rate of Cd（Ⅱ） was able to reach 94% with the above enhanced coagulation process,when the initial concentration of Cd（Ⅱ） in the raw water was at 0.08 mg/L,that is,15 times as high as the standard concentration limit.The residual Cd（Ⅱ） in the treated outflow water also proves not to meet the state water quality standard for most current traditional water treatment plants which used PAFC as coagulant and sodium silicate as coagulant aids,if the initial concentration of Cd（Ⅱ） in raw water exceeded 0.02 mg/L.Such a situation can be improved by raising the pH value and adding sodium carbonate to the water to be treated.