饮用水水源突发性Cr(Ⅵ)污染应急处理实验研究

Case study on the emergency treatment of accidentally polluted water-source by Cr(Ⅵ)

针对水源水突发性Cr(Ⅵ)污染进行了应急处理的实验研究。当原水中Cr(Ⅵ)质量浓度超过0.100 mg/L时,水厂现行处理工艺不能保证Cr(Ⅵ)达标去除。用硫酸亚铁还原法去除水中的Cr(Ⅵ),当原水中Cr(Ⅵ)质量浓度为0.1～2.0 mg/L,pH值在6.5～8.0时,硫酸亚铁和氯化铁的投量分别控制在3.0～16.0 mg/L和5～15 mg/L,可保证出水总铬质量浓度低于0.02 mg/L,去除率在99%以上,保障了饮用水水质安全。

The given paper intends to present an experimental study carried out by the author on the emergency treatment of water source that would be accidentally polluted by Cr（Ⅵ）. The results of our experimental research showed that when the concentration of Cr（Ⅵ） in water source was higher than 0. 100 mg/L, it would be impossible for the polluted water source to get purified if it were treated with the traditional treatment methods. It is also proved that Cr（Ⅵ） can not be directly removed by traditional water treatment processes as Cr（Ⅵ） can hardly form colloidal particles. Therefore, a method has been proposed to reduce Cr（Ⅵ） to Cr（Ⅲ） with ferrous sulfate. By this method, Cr（Ⅵ） can be reduced to Cr（Ⅲ） firstly, then Cr（Ⅲ） tends to form Cr（OH）3 precipitate, and, then, traditional process could remove the Cr（OH）3.In so doing, it would be desirable that pH be maintained from 6.5 to 8.0 and that ferrous sulfate be added in no less than in 2 min before the addition is done. However, when the concentration of Cr（Ⅵ） in the water source is 0.1 -2.0 mg/L, proper dosage of ferrous sulfate and ferric chloride should be 3.0 - 16.0 mg/L and 5 - 15 mg/L, respectively, so that the total mount of Cr in the water to be removed can be decreased to below 0.02 mg/L, in which the highest removal rate can be promoted to no less than 99 % when this method is applied. And, thus, the quality safety of the drinking water source can be guaranteed.