Formatted Title

Electrochemical Oxidation Field Demonstration for PFAS Destruction: What Could Possibly Go Wrong?

Background/Objectives

Separating PFAS from low concentration waters produces a waste that must be disposed of or destroyed. A treatment train that combines PFAS separation and concentration with a PFAS-focused destruction technology is an effective remediation model. Coupling PFAS concentrating technologies with DE-FLUORO™ electrochemical oxidation (EO) treatment was demonstrated in the field to determine its effectiveness for destroying PFAS in different concentrates and to optimize the design of full-scale treatments. This abstract refers to three field demonstrations—one complete and two scheduled for early 2024— of a mobile DE-FLUORO system known as “Pike.” The DE-FLUORO PFAS destruction technology has advanced from bench-scale to pilot to field demonstration with applications varying from stand-alone systems to ones specifically designed to couple with PFAS concentrating technologies. The benefit of performing multiple field demonstrations is that lessons learned from the previous studies can be used to modify and improve each system prior to the next demonstration. Given the challenges and cost to society of PFAS remediation, our objective is to optimize EO performance within a PFAS treatment train that may include separation, concentration, and, of course, destruction for a more cost-effective solution.

Approach/Activities

In each demonstration, the Pike mobile unit is mobilized to a PFAS-impacted site for coupling with a concentrating technology. We first evaluated treating secondary foamate derived from surface water and groundwater treated using an on-site surface activated foam fractionation (SAFF) system provided by EPOC and operated by AECOM. At a second site we deployed Cyclopure’s DEXSORB®--a novel sorbent--that removed PFAS from groundwater prior to onsite sorbent regeneration. EO treatment of PFAS-laden regenerant was optimized at the bench scale before deploying Pike for on-site treatment. At the third site, Pike was coupled again with the SAFF technology but this time in a closed loop system where the SAFF foamate is treated by EO and effluent is recirculated into the SAFF. In each demonstration, we evaluated the destruction efficiency by testing for targeted PFAS and total organic fluorine (TOF). In addition, we analyzed for select anions, total organic carbon, and metals. Simultaneously, we monitored operational parameters: pH, temperature, current, and voltage. Ultimately, the goal was to identify operational improvements that support future commercial operations.

Results/Lessons Learned

Limited modifications to Pike were made while onsite and enabled larger modifications between site deployments to improve the system operations. We will share EO operational performance data, and address the system improvements made to optimize destruction, including changes to temperature control, aerosol management, air emissions control, foam control, and maintenance tasks. Lessons learned will also be shared on site-specific concerns, such as having operated at ambient temperatures ranging from -10 to 90 degrees Fahrenheit, and adapting to the ethanol-based regenerant solution used by Cyclopure. The first demonstration achieved 98% reduction of TOF and up to 99% reduction of regulated PFAS. Additionally, observed operational differences in treating surface water- and groundwater-derived foamate demonstrated EO’s flexibility to achieve PFAS destruction while managing foam, filters, pH, and conductivity. The results of all three demonstrations of Pike will reflect the effectiveness of design changes as treatment optimization continues, and how that can be incorporated into a treatment train.