Novel filtration devices for iAs reduction

ABSTRACT: PROJECT 4 Approximately 15% of the United States population, and 25% of North Carolinians, rely on private wells as their drinking water source. Private wells are not regulated under the Safe Drinking Water Act and therefore their use as drinking water sources carries increased risk of exposure to waterborne contaminants such as inorganic arsenic (iAs). Long-term exposure to iAs has been linked to adverse health outcomes such as cancer, diabetes, and cognitive deficits in children. To limit adverse health outcomes, the US Environmental Protection Agency (EPA) established a drinking water maximum contaminant level (MCL) of 10 g/L and a maximum contaminant level goal (MCLG) of zero. However, approximately 2.1 million people in the US drink water from private wells contaminated with iAs above the MCL, with concentrations as high as 800 µg/L in NC. The US EPA and NC Department of Health and Human Services (DHHS) recommend pressure-driven reverse osmosis (RO) membrane filtration to remove iAs from well water because RO requires the fewest chemicals and steps to remove iAs and is easy to implement. However, application of RO for iAs removal has two primary challenges: (i) RO inadequately removes As(III) (i.e., the most hazardous iAs species) despite removing As(V) effectively, and (ii) RO suffers of low water productivity (e.g. under-the-sink RO systems purify only ~15% of the input water). The goal of Project 4 is to develop a novel membrane technology that addresses these two fundamental challenges in current membranes for iAs removal. We hypothesize that novel (patent pending) pressure- driven membranes endowed with electrically conductive properties will enable the simultaneous increase of water productivity and iAs removal, particularly of As(III), without chemical pretreatment. Our hypothesis is supported by initial findings showing that we can use our platform method for fabrication of electrically conductive membranes (ECMs) to develop ECMs with a broad range of performance that can simultaneously oxidize As(III) into As(V) and remove iAs. We will accomplish our goals via three specific aims: (1) Develop scalable ECMs with greater iAs removal and water productivity than currently available commercial RO membranes; (2) Elucidate iAs transport mechanisms in ECMs; and (3) Compare ECM performance to that of a benchmark RO membrane using a range of NC private well water samples and prolonged operation at pilot scale. Project 4 addresses the theme of the UNC-SRP "Protecting vulnerable populations from arsenic-induced metabolic dysfunction with a vision for exposure reduction and disease prevention" and is responsive to Mandates 3 and 4 of the NIEHS SRP as it focuses on advanced methodologies to detect hazardous substances in the environment and methods that reduce the amount and toxicity of toxic substances in the environment. The proposed work is significant and innovative, as it will develop novel membrane technology to reduce exposure to iAs and elucidate fundamental understanding of transport in ECMs to enable continued ECM optimization.