As(Ⅲ)污染水源应急处理技术的中试研究

Pilot Scale Study on Emergent Treatment for As(Ⅲ) Pollution in Water Source

以我国目前广泛采用的常规净水工艺为基础，开展了水源突发性As（Ⅲ）污染的应急处理工艺中试研究，考察了不同的氧化剂种类、投加量、投加点和不同污染物浓度水平对应急处理工艺效果的影响以及As（Ⅲ）的去除机制．结果表明，当原水As（Ⅲ）为150μg／L，常规处理工艺对As（Ⅲ）的去除率仅为71．85％，其中溶解态的砷和总砷在快速混合、一级絮凝、二絮凝、沉淀、过滤各单元去除率分别为36．00％、5．42％、9．30％、14．95％、7．88％以及9．10％、-3．62％、2．74％、55．12％、8．51％，无法将出水中的As控制在10μg／L以下．预氯化-强化混凝工艺能够将初始浓度为100～600μg／L的As（Ⅲ）控制在10μg／L以下．但在低有效氯投加量时，氨氮浓度以及预氯化点的选择会对处理效果产生影响．KMnO4预氧化一强化混凝工艺能够将初始浓度为100～600μg／L的As（Ⅲ）控制在10μg／L以下，且其处理效果明显优于预氯化，预氧化点的选择不会对处理效果产生明显影响．建议有条件的水厂优先选用KMnO4作为As（Ⅲ）的氧化剂．

Based on the conventional water treatment processes widely used in China, a pilot scale study was performed to investigate emergent treatment for arsenite pollution in water source. The results show that As removal efficiency can only reach to 71.85% by conventional water treatment process. The removal efficiencies of dissolved arsenic and total arsenic by mixing, first flocculation, second flocculation, sedimentation, filtration units were 36.00% , 5.42% , 9. 30% , 14. 95% , 7.88% and 9.10% , - 3.62% , 2.74% , 55.12% , 8.51% respectively,when the concentration of As（Ⅲ ） in raw water was 150 μg/L. The arsenic concentration in treated water can not be effectively controlled below 10 μg/L. Hence, the pre-oxidation is necessary. The pre-chlorination-enhanced coagulation process can effectively deal with the sudden As（ Ⅲ ） pollution. But for lower chlorine dosage, both ammonia concentration and different pre-chlorination sites have significant effects on arsenic removal, which should be taken into account. Potassium permanganate pre-oxidation-enhanced coagulation process can be more effectively deal with the sudden As（ Ⅲ ） pollution than prechlorination. Moreover the different pre-oxidation sites have no obvious effect on arsenic removal. As a result, potassium permanganate is recommended as an oxidant for As（Ⅲ ）.