Leaching of arsenic in response to organic matter contamination in groundwater treatment practice

Abstract

A large number of drinking water treatment units have been installed in many regions adopting the technique of arsenic removal through adsorption and co-precipitation with the naturally occurring iron in groundwater and subsequent sand filtration. This study revealed the consequence of the organic matter inclusion on the arsenic treatment process for drinking water. Laboratory investigation confirmed that the organic contamination in the treatment process impeded the arsenic removal efficiency depending on the types and concentrations of the organic matters. The impact of organic matter contamination on the arsenic removal efficiency was almost immediate and the autoclaved examination showed similar results. Nevertheless, the bioleaching of arsenic, 93 μg/L, from the accumulated sludge in the filter bed was observed under the inoperative condition, for 7 days, of the treatment unit. However, in the control observation (using organic matter plus antibiotic) the effluent arsenic concentration was found to be less than 30 μg/L. The effluent iron concentration in the bioleaching process was not worth mentioning and found to be less than 0.22 mg/L. In this study, the chemical and biological consequences of the organic matter contamination on the arsenic removal practice is elucidated, which might contribute in designing safe options for drinking water.