Project Summary (2020-2025)

Study Objectives: The goal of this project is to develop and test a portable, low-maintenance, and self-cleaning water purification technology for both point-of-use and point-of-entry water treatment. A novel electro-Fenton (EF)-like Electrochemical Advanced Oxidation Process (EAOP) is being coupled with sorption using practical, cost-effective, environmentally friendly carbon-based porous cathodes. Two approaches are being implemented: (1) removal of organic mixtures from the water via adsorption by carbon-based electrodes, then regeneration of the adsorbent via application of the EAOP on the carbon-based porous cathode surfaces to locally generate reactive oxygen species (ROS); and (2) simultaneous application of adsorption and EAOP. The motivation for this work is the need to provide clean water to communities near Superfund sites in Puerto Rico that lack access to clean water after the devastation of Hurricane Maria in 2017, as well as the need for a water treatment technology that can be used in rural areas.

Study Approach: Laboratory studies are being conducted using water collected from the study area in Puerto Rico. Target chemicals include chlorinated solvents, phthalates, pesticides, and polycyclic aromatic hydrocarbons (PAHs). Mechanistic studies are investigating continuous generation of ROS without addition of traditional catalysts (Pd, Fe) that are expensive, waste-producing, or potentially toxic. Instead, the researchers are using three types of benign carbon-based cathodes: Granular Activated Carbon (GAC), Activated Carbon Fiber (ACF), and Granular Biochar (GB). Enhancement techniques that include polarity reversal and floating cathodes are being tested, and conditions that maximize continuous generation of ROS are being identified. Sorption characteristics of the three carbon-based cathodes are being measured, and EAOP's ability to regenerate the sorption capacity of the cathodes and simultaneously oxidize aqueous contaminants are being tested. To improve understanding of transformation pathways and mechanisms, the researchers are measuring changes in concentration of target organics and analyzing newly formed by-products. For these laboratory tests, water collected from Puerto Rico is being mixed with model contaminants and used for testing. The variations in toxicity levels and mechanistic profiles during the course of the electrochemically induced degradation is disclosing potential causal agents and their links to the degradation pathways. Scaling of operational parameters and performance, geochemical and hydraulic parameters during operation, toxicity evolution, and potential adverse effects are being investigated. The researchers are also assessing the risk reduction efficacy of the process using a novel toxicogenomics-based toxicity assessment.

Expected Results: Based on this technology, a portable water, self-cleaning treatment system will be designed and tested on water samples from Puerto Rico. The system will be engineered for inclusion into both point-of-use and point-of-entry water treatment systems and can also be implemented in rural areas in the U.S. mainland that are not connected to public water systems.