Use Chemical Precipitation To Remove Excess Flouride、Hardness And Suflate From Driking Water

Safe rinking water is a necessary condition to maintain normal human metabolism and protect human health.Shanxi Province is one of the severe shortages of water resources provinces, combined with the unique climate and terrain conditions and the water resources is contaminated in recent years, so many areas the safety of drinking water has been more prominent, especially rural residents. In 《Drinking Water Standards(GB5749-2006)》 set fluoride concentration<1.0mg/L,hardnessconcentration<450mg/L,sulfate concentration<250mg/L.If drinking water is exceed the limits are exceeded water quality. Although the process of reverse osmosis membrane and ion exchange have better treatment effect of such water. But they have one-time investment of equipment, high operating costs, operational difficulties such shortcomings. More suitable for large-scale centralized water supply, not suitable for Some scattered users.In this paper, aimed to simulate five kinds of water quality common in dewater sources, such as fluoride, hardness, sulfate, fluoride and hardness, fluoride and sulfate trace exceeded.Selected chemicals precipitant used to treat these five kinds of water quality by chemical precipitation. The experimental results are as follow:1、Use CaO and CaCl2as a precipitating agent to treat the fluoride exceeded raw water, the optimum dosage is450mg/L and350mg/L, by magnetic stirrer stir1h, water fluoride concentration from1.65mg/L were reduced to0.96mg/L and0.87mg/L, after treatment water pH and total hardness did not exceed the national drinking water standards.CaCl2as precipitating agent the optimum reaction time is30min, optimum pH is7.Less the cost of treatment the same amount of water of the two precipitating agent.2. Use KH2PO4. CaO and Na2CO3as a a precipitating agent to treat the hardness exceeded raw water, the optimum dosage is1.5g/L,215mg/L and160mg/L, by magnetic stirrer stir1h, water hardness concentration from812mg/L were reduced to402mg/L、340mg/L, after treatment water pH is8.37not exceed the national drinking water standards. KH2PO4as precipitating agent the optimum reaction time is40min.Treatment the same amount of water CaO and Na2CO3is cheap than KH2PO4.3、Use BaCl2and CaCl2as a a precipitating agent to treat the sulfate exceeded raw water, the optimum dosage is650mg/L and330mg/L, by magnetic stirrer stir1h, water sulfate concentration from512mg/L were reduced to227mg/L and263g/L, after treatment water pH is7.61not exceed the national drinking water standards. BaCl2as precipitating agent the optimum reaction time is30min. Treatment the same amount of water CaCl2is cheap than BaCl2.4、Use CaO and Na2CO3as a a precipitating agent to treat the fluoride and hardness blended exceeded raw water, the optimum dosage is280mg/L and180mg/L,water fluoride concentration from1.55mg/L were reduced to0.82mg/L,and hardness concentration from683mg/L were reduced to264mg/L.After treatment water pH is8.53,not exceed the national drinking water standards. Optimum reaction time is60min.5、Use CaCl2as a precipitating agent to treat the fluoride and sulfate blended exceeded raw water, the optimum dosage is720mg/L,water fluoride concentration from1.42mg/L were reduced to0.94mg/L,and sulfate concentration from612mg/L were reduced to327mg/L.Afte treatment water pH is,not exceed the national drinking water standards. Optimum reaction time is60min.In this study, by chemical precipitation method five simulation water qualities is not the national drinking water standards index. Although there is no good the water quality of the reverse osmosis membrane and ion exchange process. However, the method is simple and easy to operate. By computing the same volume of water costs far lower than other processes. Therefore, the method can be effectively alleviate some of the centralized water supply in remote mountainous areas and decentralized user of safe drinking water.