Biological oxidation of arsenite in synthetic groundwater using immobilised bacteria

• Published in: Water research (Oxford) Vol. 46; no. 15; pp. 4825 - 4831
• Main Authors: Ito, Ayumi, Miura, Jun-ichi, Ishikawa, Nao, Umita, Teruyuki
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.10.2012; Elsevier
• Subjects: activated sludge; Applied sciences; arsenic; arsenites; Arsenites - metabolism; bacteria; Bacteria - classification; Bacteria - genetics; Bacteria - metabolism; Biological arsenite oxidation; bioreactors; DNA, Ribosomal - genetics; Ensifer adhaerens; Exact sciences and technology; Groundwater; Groundwater - microbiology; Hydraulic retention time; Immobilised bacteria; nitrogen; oxidation; Oxidation-Reduction; Phylogeny; Pollution; pretreatment; RNA, Ribosomal, 16S - genetics; temperature; Water treatment and pollution; Hydraulic retention time; Groundwater; Biological arsenite oxidation; Immobilised bacteria; Activated sludge; Arsenic; Nitrogen; Retention time; Arsenites; Biological purification; Trace element; Carcinogen; Bioreactor; Batchwise; Bacteria; Poison; Oxidation; Waste water purification; Ground water
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2012.06.013

Biological oxidation of arsenite (As(III)) in synthetic groundwater was examined by using arsenite oxidising bacteria (AOB) isolated from an activated sludge. The phylogenetic analysis indicated that the isolated AOB was closely related to Ensifer adhaerens. Batch experiments showed that for an As(III) oxidation with the isolated AOB the optimum ratio of nitrogen source (NH4-N) concentration to As(III) concentration was 0.5 (52 mg/L–110 mg/L) and the isolated AOB preferred pH values ranging from 6 to 8, and water temperatures greater than 20 °C. Further continuous experiments were conducted using a bioreactor with immobilised AOB. With an initial As(III) concentration of 1 mg/L at a hydraulic retention time (HRT) of 1 h, an As(III) oxidation rate was around 1 × 10−9 μg/cell/min and an As(III) oxidation efficiency of 92% was achieved. Although the maximum oxidation rate measured at an HRT of 0.5 h was 2.1 × 10−9 μg/cell/min, the oxidation efficiency decreased to 87%. These results advocate that a biological process involving immobilised AOB may be useful as an economical and environmentally friendly pre-treatment step for As removal from groundwater. [Display omitted] ► As(III) oxidising bacteria were isolated from activated sludge. ► Some optimum conditions were obtained for microbial As(III) oxidation. ► Continuous As(III) oxidation was achieved using a bioreactor at an HRT of 0.5 h.