Light-Based Approaches to Effective and Sustainable Removal of Arsenic and Uranium from Drinking Water Sources

Project 5 Summary The Columbia University Northern Plains Superfund Research Program (CUNP-SRP) seeks to reduce exposure to arsenic (As) and uranium (U), frequently found in excess of safe limits on tribal lands in North and South Dakota and elsewhere. In these areas, drinking water is primarily derived from groundwater. This reliance often results in people using untreated or insufficiently treated water from private wells that is unfit for consumption. Community water systems (CWSs) also use groundwater and often fail to limit As and U contamination to safe levels despite treatment. Inadequate removal of As and U by conventional water treatment stems from the limited adsorption of their most abundant forms in groundwater, As(III) and U(VI), and due to the limited sorption capacity of media. Importantly, these As and U exposures are associated with cardiometabolic disease, which exerts a disproportionately high burden in Native American populations. The overall goal of Project 5 is to decrease exposure using novel point-of-use filtration and point-of-entry treatment systems that use light to create media and enhance As and U sorption by simultaneously oxidizing As and reducing U. Our technology is based on an efficient, photosynthetic microbial battery that generates reactive treatment media by cycling iron (Fe), which is ideal to remove chemical contamination from groundwater. This approach takes advantage of the aqueous composition of input water and microbial communities, which often contain reduced forms of Fe(II) and manganese (Mn(II)) and/or nitrate, in addition to metal(loid) contaminants. Specific aims will address the underlying processes to optimize this novel water treatment technology and the necessary monitoring needed to ensure system performance. In Aim 1, media will be generated by harnessing natural microbial populations from groundwater that are powered by light and the chemical energy stored within water to create Fe oxide media. In Aim 2, enhanced treatment will be obtained through heterogeneous photocatalysis that selectively and simultaneously can reduce and oxidize groundwater contaminants to less soluble forms. In Aim 3, we will develop and integrate a real-time, water quality monitor in the treatment system to ensure that the system performs to specifications and to be able to alert the user and/or water treatment company before the system fails. Each aim targets development of a commercially viable product. This project remediates As and U in groundwater, common contaminants at Superfund sites and some of the most widespread contaminants in the US, especially in rural communities. These remediation approaches will be tested and implemented in the Northern Plains in areas with As and/or U affected drinking water. Implementation will allow us to pilot the use of this novel treatment method under a wide range of water compositions and with typical use patterns. Ultimately, the novel water remediation technologies developed in this project are expected to provide a feasible and effective means to reduce potentially harmful exposures to drinking water contamination in our target communities and other at-risk populations, including communities near Superfund and other hazardous sites.