Bioleaching of arsenic in a drinking water treatment process

Abstract

Arsenic is found to exist within the shailow zones of groundwater in many countries and a iarge number of drinking water treatment units have been instaiied to combat this arsenic poisoning.Microbial activity can greatly affect the mobiiization of arsenic under anaerobic conditions when coupied with the oxidation of organic matter, in this study, the bioleaching of arsenic in response to organic matter inclusion in a drinicing water treatment process has been elucidated.The decomposition of organic matter due to the microbial action has led to an anaerobic condition within the accumulated sludge in the treatment unit and hence caused the bioleaching of arsenic, above l30tig/L, with the effluent water. Nevertheless, the biofilm structure, related to the oxygen penetration, had significant influence on the bioieaching of arsenic even in the circumferential aerobic condition of the biofllm. For a biofilm thickness around 400 fxm, an anaerobic bottom part was noticed and hence a clear step-up concentration of arsenic was observed in the associated bulk liquid. This study suggests that organic matter would have a sufficiently important influence on the microbiological transformation of arsenic to warrant its consideration in designing safe remediation strategies in the context of arsenic removal processes for drinking water. K M. Hassan et al. Btoleachlng of arsenic in a drinking water treatment process Journai of Water Supply: Research and Technology-AQUA | 58 6 | 2009 te M. Hassan ef al. Btoieaching of arsenic in a drinking water treatment process Journal of water Supply: Research and Tectinology-AQUA | 58,6 | 2009 K. M. Hassan et al. \ Bioleaching of arsenic in a drinking water treatment process Journal of Water Supply: Research and Technology-AQUA | 58.6 | 2009 K, M. Hassan et al. Bioleaching of arsenic in a drinking water treatment process Journal of water Supply: Research and Technology-AQUA | 58.6 | 2009 K. M. Hassan ef al. \ Bioieaching of arsenic in a drinking water treatment process

Potential of biological arsenite oxidation in sand filtration units at arsenic–iron removal plants (AIRPs) in Bangladesh

“…The observation has been linked with changing of the solid phase to the dissolved phase of arsenic. Previous report (Hasan et al 2009) described mechanism of bioleaching associated with sand filter bed that creates a biofilm in pore space and top of the surface of the bed creating an anaerobic condition that facilitates the bioleaching of arsenic in the outlet water. This mechanism may probably be responsible for the increment in D-As obtained in this study.…”

“…Thus, MAIRP is not sufficient for arsenic removal. Meanwhile, increment in concentration may be induced by the sediments in the sedimentation pond as described by Hasan et al (2009). It is therefore suggested that periodic removal of sediment will help to avoid the leaching of arsenic.…”