[Pilot scale study on emergent treatment for As (III) pollution in water source]

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 microg/L. The arsenic concentration in treated water can not be effectively controlled below 10 microg/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 pre-chlorination. 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).