Studies On The Removal Performance Of Natural Organic Matter And Pyrethroid In Drinking Water

Reservoirs and other surface water are sources of drinking water in most southwest mountain villages. Affected by rainfall and agricultural production activities, natural organic matter and pesticide residues are the major pollutants of these water sources. And they are the main challenges that mountain villages water plants faced with in water treatment process, the simple conventional process of these water plants can not meet the treatment requirements of such raw water.Field survey on the process and water sources of southwest village water plants found that the permanganate index of most reservoirs exceed class III of the surface water environmental quality standard, the organic content is at a high level. Pyrethroids such as permethrin, cypermethrin, deltamethrin are detected in raw water with low residual levels during the dry season, but the detection rate is high.In this paper, research program is developed based on the the characteristics of water quality in southwest mountain villages. The pollution process of natural organic matter and pyrethroids is simulated in laboratory. Select PAC, aluminum sulfate, PFS, ferric chloride as coagulants in the conventional process, the removal performance of NOM and pyrethroids is researched. PAC is screened out as the best coagulant and the optimum dosage is 20mg/L. Select potassium permanganate, hydrogen peroxide, chlorine dioxide as oxidants in pre-oxidation test. The test results confirmed that the strengthening effect is not significant in each dosage gradient of these oxidants. To some extent, the oxidants affected the coagulation effect of PAC. Finally, select diatomite, bentonite, kaolin in enhanced coagulation tests, the results confirmed that the strengthening effect of these clay minerals on coagulation is significant. And the optimal clay mineral is diatomite, the optimum dosage is 30mg/L.The pilot plant is designed depending on the characteristics of NOM and pyrethroids combined with the defect of water plants in southwest mountain village. Set a BAF in front of conventional process and set an activated carbon adsorption tank after gravity valveless filter. Research on the removal performance of NOM and pyrethroids under the combined treatment process of bio-oxidation + normal process + activated carbon adsorption. Pilot test is conducted in Shui Mo water plant of Yunyang County. The dosing conditions of PAC and diatomite are magnified, and the results are similar to the results of lab test. The combined treatment process of aeration biological oxidation + normal process + activated carbon adsorption have a better treatment effect than the traditional process when the pilot plant operate at optimum conditions, and the pollutants such as suspended solids, NOM, pyrethroids, ammonia have a higher removal rate. The BAF and activated carbon adsorption tank are the most important units in the remove process of NOM, pyrethroids, ammonia. The combined process has a large advantage compared to the conventional process in dealing with NOM, pyrethroids, ammonia and other pollutants in raw water. Recommend that use the combined processes in the improvement of water plants in southwest mountainous villages or the same type plants in other area.