分散式饮水除砷研究

Study on Removal of Arsenic From Decentralized Drinking Water

目的研究分散式饮水除砷技术。方法采用混凝沉淀和涂铁砂粒吸附除砷。若源水中含有三价砷 ,可在混凝沉淀前将其氧化。结果在不调 pH值、人工搅拌和室温条件下 ,如果混凝后进行砂滤 ,当源水五价砷含量小于0.5mg/L和为0.5～1.0、1.0～2.0mg/L时。分别投加硫酸铁20、30、60mg/L ,均可使处理后出水砷含量小于0.05mg/L。若三价砷含量为1.0mg/L ,按有效氯计投加2.5mg/L次氯酸钠预氧化 ,在相同条件下 ,可使三价砷的去除率与五价砷相同。用涂铁砂粒吸附三价与五价砷 ,均可使出水砷含量小于0.01mg/L。结论硫酸铁、硫酸铝及其混合物是较实用的分散式饮水除砷剂 ,次氯酸钠为适宜的三价砷氧化剂。涂铁砂粒能有效地吸附三价与五价砷 。

Objective To study the technologies of the removal of arsenic from decentralized drinking water. Methoods The removal of arsenic adopted the coagulation_precipitation and adsorption by the iron oxide_coated sand (IOCS). If arsenite existed in source water, it was oxidated before coagulation_precipitation. Results After coagulants and employing sand filtration, when the original concentrations of arsenate were <0.5, 0.5～1.0 and 1.0～2.0 mg/L by using 20, 30 and 60 mg/L ferric sulfate, the residual arsenate in filtered water could meet the valid health standard of drinking water (<0.05 mg/L) in the conditions of pH value not regulated, an artificial stir and room temperature. When the original concentration of arsenite was 1.0 mg/L, after adding 2.5 mg/L sodium hypechlorite for pre_oxidation, the removal rates of arsenite reached the one of arsenate in the same conditions. Arsenite and arsenate could be adsorbed by IOCS. The remained arsenate in water supply was even less than 0.01 mg/L. Conclusions Ferric sulfate and aluminum sulfate and their mixture were feasible for removing arsenic from decentralized drinking water system. And sodium hypochlorite was an effective oxidant for arsenite. The arsenite and arsenate could be effectively adsorbed by IOCS. And the performance of IOCS was stability.