Nearly 90% of wastewater in developing countries is currently discharged directly into water bodies causing major environmental health risks. The growing gap between urban water demand and supply, exacerbated by water pollution and severe droughts, has spurred a paradigm shift in augmenting conventional centralized urban water systems with distributed treatment and reuse of locally available water supplies, such as municipal wastewater, to increase urban water security. Although such systems could be useful in many applications, adoption of the technology requires cost-effective, reliable removal of pathogens, trace organic contaminants, and pollutant metals. Electrochemical water treatment technologies are advantageous for small-scale, distributed water treatment because they can be installed quickly without large capital investment and reactants can be generated on demand, solely though the input of electrical energy. Iron-based electrochemical technologies are promising because of their selective oxidation performance and in situ generation of high surface area sorbents. For example, a small DC voltage applied to a zero valent iron anode readily produces Fe(II) species that react with dissolved oxygen to form insoluble Fe(III) (oxyhydr)oxides, known sorbents of organic and inorganic contaminants. However, the kinetics of Fe(II) oxidation by dissolved O2 is too slow to treat the high flow rates needed for point-of-use recycling of wastewater. Therefore, this research investigates the efficacy of iron electrocoagulation when combined with a carbon-based air diffusion cathode that generates H2O2 directly from the ambient air in order to remove persistent organic contaminants (e.g., endocrine disrupting compounds, pharmaceuticals, and personal care products). Employing a carbon-based air diffusion cathode to generate H2O2 in the presence of Fe(II) promotes rapid Fe(II) oxidation and generates a high yield of oxidants through a Fenton reaction (e.g., Fe(IV) and *OH), providing removal of emerging contaminants via oxidation and adsorption. Our results elucidate the influence of matrix composition, pH, and current density on the removal of select organic contaminants by air-cathode iron electrocoagulation.

Air cathode iron-electrocoagulation for removing wastewater-derived contaminants of concern

256th National Meeting (2018)

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