WaTER Center Master’s student and NSF Fellow Chris Cope is studying the adsorptive capacity of iron-amended rice husk char for removing arsenic from groundwater. Arsenic is a naturally occurring contaminant in much of the groundwater used for drinking water worldwide. Although mitigation techniques exist, they often are not cost-effective for people in developing countries. Cope, under the guidance of Dr. David Sabatini, traveled to Cambodia to test the effectiveness of the medium at filtering arsenic in June of 2011 and will return this June.
As Cope explains, for most Cambodians rainwater is the preferred source of drinking water. However, few people can afford vessels that will hold enough rainwater to sustain them through the dry season. Because of this, Cambodians rely on multiple sources of drinking water throughout the year, including wells. While many wells have been drilled, making water more easily accessible, little attention has been paid to water quality. As the reliance on groundwater for drinking has increased, so have cases of arsenic poisoning, or arsenicosis.
Arsenicosis is a disease that results from consuming too much arsenic over an extended period of time. Arsenicosis can lead to a number of skin problems, cancers, and cardiovascular diseases. According to the World Health Organization, individuals who consume arsenic contaminated drinking water for more than five years are especially susceptible. Furthermore, WHO reports that malnutrition can increase the vascular damage done by arsenic. This is especially significant for developing countries where poor water quality often coincides with limited food supply.
Providing drinking water in developing countries, therefore, must include provisions for mitigating natural contaminants like arsenic. The WaTER Center has been working to achieve a cost-effective solution, and Cope's research is an extension of the Center's efforts. WaTER Center researchers initially tried to coat sand. Although there was some success with the iron-coated sand, its surface area was not large enough to cause a significant decrease in the contaminant. Iron-amended rice husk char is one of several materials being considered by WaTER Center students.
Testing the adsorption capacity of the husks is the next step in Cope's analysis and the reason for his travel this upcoming summer. Cope says it is especially important for him to test his material in Cambodia because of the specific makeup of the groundwater. In the filtration process, the arsenic ions should adhere to the coated husks. However, Cope says that there are competing ions such as phosphate and sulfate in source water that will also be attracted to the husks, limiting the capacity of the husks to remove arsenic.The degree to which this occurs will greatly affect the viability of iron-amended rice husk char as a solution.
Cope says eventually he hopes that this technique of charring and coating inexpensive materials will lead to a commercially available arsenic adsorption technique. Once an ideal substance is identified, the next phase will be to put the substance in filters and to do pilot studies in other regions, such as Bangladesh.