Biological oxidation of arsenite in synthetic groundwater using immobilised bacteria.

Ayumi Ito, Jun-Ichi Miura, Nao Ishikawa, Teruyuki Umita

Department of Frontier Materials and Function Engineering, Iwate University, Ueda 4-3-5, Morioka 020-8551, Japan. aitou@iwate-u.ac.jp

Water research 2012 Oct 1

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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. Copyright © 2012 Elsevier Ltd. All rights reserved.

Citation

Ayumi Ito, Jun-Ichi Miura, Nao Ishikawa, Teruyuki Umita. Biological oxidation of arsenite in synthetic groundwater using immobilised bacteria. Water research. 2012 Oct 1;46(15):4825-31