Western Kentucky University
Arsenic Remediation of Drinking Water Using Limestone: Contaminant Interference and Surface Morphology
Institution
Western Kentucky University
Faculty Advisor/ Mentor
Cathleen Webb
Abstract
The Environmental Protection Agency has proposed lowering the Maximum Contaminant Level (MCL) for arsenic, currently set at 50 ppb or less. Current remediation technologies are expensive. This will result in increased economic pressure on rural communities with high levels of arsenic in their drinking water. The proposed lower MCL for arsenic has spurred the development of a novel remediation technology that has shown the ability to reduce arsenic in drinking water at the source, with the added benefit of low-cost disposal of a stable and benign waste product in ordinary landfills. Arsenic, at pH 8.0 and above, is known to be readily soluble and transports easily through ground water. Previous work indicates that arsenic has significant retention in contact with calcium and magnesium carbonates. This could be a result of adsorption on the limestone and dolomite mineral surfaces or precipitation. Adsorption batch tests with crushed limestone have been shown to reduce arsenic from 100 ppb to less than 5 ppb. Various common drinking water contaminants such as chloride, nitrate, iron, and sulfate were studied to determine the impact on the removal efficiency of arsenic. Typically, little interference was found. The temperature dependence of the removal surface morphology of the limestone base and the waste product was also studied. Surface exchange was done to observe whether magnesium has a better capacity to removal efficiency of arsenic.
Arsenic Remediation of Drinking Water Using Limestone: Contaminant Interference and Surface Morphology
The Environmental Protection Agency has proposed lowering the Maximum Contaminant Level (MCL) for arsenic, currently set at 50 ppb or less. Current remediation technologies are expensive. This will result in increased economic pressure on rural communities with high levels of arsenic in their drinking water. The proposed lower MCL for arsenic has spurred the development of a novel remediation technology that has shown the ability to reduce arsenic in drinking water at the source, with the added benefit of low-cost disposal of a stable and benign waste product in ordinary landfills. Arsenic, at pH 8.0 and above, is known to be readily soluble and transports easily through ground water. Previous work indicates that arsenic has significant retention in contact with calcium and magnesium carbonates. This could be a result of adsorption on the limestone and dolomite mineral surfaces or precipitation. Adsorption batch tests with crushed limestone have been shown to reduce arsenic from 100 ppb to less than 5 ppb. Various common drinking water contaminants such as chloride, nitrate, iron, and sulfate were studied to determine the impact on the removal efficiency of arsenic. Typically, little interference was found. The temperature dependence of the removal surface morphology of the limestone base and the waste product was also studied. Surface exchange was done to observe whether magnesium has a better capacity to removal efficiency of arsenic.