Batch and column laboratory experiments were conducted on natural sediment and groundwater samples from a contaminated site with the aim of lowering the dissolved arsenate [As(V)] concentrations by enhancing natural attenuation. In factorial batch experiments, two levels of treatment for pH adjustment, Ca and Fe additions were studied for impact on As(V) solubility. Results showed statistical significance for the effect of pH, Ca and Fe on increased sorption capacity of sediments. Additionally, adsorption isotherm experiments at three levels of Ca showed consistent increase in adsorption capacity (26-37%) indicating that the beneficial effect of Ca is due to improving the adsorption rates on surfaces likely by increasing the surface positive charges. Column experiments were conducted by flowing contaminated groundwater with elevated pH, As, and PO<sub>4</sub> through both uncontaminated and contaminated sediments. Potential remediation scenarios were simulated by adding a chemical amendment line to the columns input injecting Fe(II) and Ca as well as simultaneous pH adjustment to the groundwater inflow. Results showed temporary and limited decrease in As(V) concentrations by Ca treatment (39-41%) and higher levels of attenuation in Fe(II) treated columns (50-91%) but given the sufficient number of pore volumes(18-20 pore volumes).

Remediation of As(V) contaminated groundwater through enhanced natural attenuation: Batch and column studies

251st National Meeting (2016)

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