Development of innovative arsenic removal apparatus from groundwater using arsenite oxidizing bacteria

地下水中砷的摄入对人体健康造成严重损害，特别是在亚洲地区。为了通过混凝或吸附去除地下水中的砷，需要将地下水中的亚砷酸盐氧化为砷酸盐。本研究从活性污泥中富集亚砷酸盐氧化菌，进行16S rRNA基因分析。结果表明，亚砷酸盐的氧化与根瘤菌有关。细菌氧化亚砷酸盐的最佳条件为pH 7和30℃。为开发一种新型的无曝气、无氧化剂、无絮凝剂的除砷装置，对固定化亚砷酸氧化菌下流式悬挂海绵反应器进行了试验研究。结果表明，当亚砷酸盐和亚铁流入浓度分别为0.5 mg/L和25 mg/L时，砷的平均去除率约为95%。该效率符合饮用水水质标准0.01 mg/L。

The health impairment caused by ingestion of the arsenic in groundwater is serious especially in Asian areas. In order to remove arsenic in groundwater by coagulation or adsorption, arsenite in groundwater needs to be oxidized to arsenate.In this research, arsenite-oxidizing bacteria are enriched from activated sludge, then 16S rRNA gene analysis was conducted. It was suggested that Rhizobium sp. is responsible for arsenite oxidation. The optimum conditions for arsenite oxidation by the bacteria were pH 7 and 30 degrees Celsius. For developing an innovative arsenic removal apparatus without aeration, oxidizer, and flocculant, a Down-Flow Hanging Sponge reactor with fixed arsenite-oxidizing bacteria was examined. As a result, when the inflow concentrations of arsenite and ferrous iron 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.