Abstract
The health impairment caused by ingestion of the arsenic in groundwater is serious especially in Asian areas. Ferrous iron (Fe (II)) is detected in groundwater with arsenic. In order to improve the efficiency of coagulation or adsorption process for arsenic removal, arsenite (As (III)) which is a predominant form in groundwater needs to be oxidized to arsenate (As (V)) as a pretreatment. In this research, arsenite-oxidizing bacteria are enriched from activated sludge, then 16S rRNA gene analysis was conducted. Arsenite oxidization characteristics under different culture conditions (DO, pH, and temperature) were examined and the optimum conditions of pH and temperature were 7 and 30°C, respectively. For the purpose of developing an economical arsenic removal method without an aeration equipment, an oxidizer, and a flocculant, a Down-Flow Hanging Sponge (DHS) reactor with fixed arsenite-oxidizing bacteria was examined. As a result, when the inflow concentrations of As (III) and Fe(II) were 0.5 mg/L and 25 mg/L, respectively, the average arsenic removal efficiency was about 95 %. This efficiency was correspondent to the water quality standard for drinking water value of 0.01 mg/L.
