Microwave Irradiation-enabled Household On-site Regeneration of Activated Carbon for Sustainable Point-of-Use Removal of PFAS in Drinking Water

Millions of the U.S. people across this country rely on household water treatment (HWT), accomplished by deploying point-of-use (POU) or point-of-entry (POE) devices, for drinking water. However, per- and polyfluoroalkyl substances (PFAS) broadly found in the U.S. drinking water are challenging established HWT technologies. Some of them (e.g., ceramic filters) poorly alleviate PFAS, while others (e.g., RO filtration and granular activated carbon (GAC)), though effective, remained challenged due to inherent technical and economical restrictions. Particularly, they cannot destruct toxic PFAS to provide an ultimate solution to PFAS pollution. Challenges for POU removals of PFAS in drinking water include: 1) trace concentrations; 2) low lifetime health advisory or maximum contaminant levels; 3) persistence; 4) prevalence; and 5) fewer technology options available for the POU scenario. Therefore, development of innovative POU treatment methods for PFAS in water is urgently needed. This project aims to validate, optimize, and demonstrate microwave (MW) irradiation-enabled thermal destruction of PFAS sorbed on activated carbon, thereby enabling a design capable of demonstrating long-term performance for cost-effective POU removal of PFAS in drinking water. Although GAC-based POU filters have proven for effective removal of PFAS, this option is unsustainable due to the lack of on-site adsorbent regeneration. Here, a household microwave oven will be applied to treat PFAS-spent GAC, for thermal destruction of PFAS (detoxification); and recovery of GAC adsorption (regeneration), to achieve a cyclic POU treatment approach. Novelty of this project is embodied in five interrelated domains, including: a) Treatment quality (MW thermal regeneration permits recurring GAC adsorption of PFAS, while chemically destructing toxic PFAS). b) Environmental friendliness (low energy footprint due to rapid MW regeneration; less GAC wastes; and minimal leaching from GAC). c) User experience (household MW ovens makes the operation easy). d) Economic viability (no financial needs for additional equipment except MW ovens (a common kitchen appliance); repeated use of GAC; and lower expenses for less waste disposal). And e) Social acceptance. The above-stated merits foster public acceptance and market adoption. The problem-driven research will have profound, long-term, and multiple benefits to the U.S, such as reduction of POU costs, protection of environmental and human health, and decrease of the POU treatment residuals.