Electrochemical Oxidation and Granular Activated Carbon Sequential Treatment for PFAS Destruction in Contaminated Groundwater: Removal Efficiency, Byproduct Formation, and Energy Cost Analysis

This study investigates sequential granular activated carbon (GAC) adsorption and electrochemical oxidation treatment train for PFAS-contaminated groundwater: removal efficiency for 40 PFAS compounds, fluoride byproduct recovery, and energy cost per liter treated within the context of environmental engineering and water remediation technology, an area of growing scientific importance given its implications for military base PFAS groundwater remediation system design, GAC regeneration economics, and PFAS destruction technology regulatory approval support. Using bench-scale GAC column (EBCT 10 min) followed by BDD electrochemical flow cell at current densities 10-100 mA/cm2, with LC-MS/MS quantification of 40 PFAS compounds and fluoride ion chromatography for defluorination tracking, we examine GAC adsorbing long-chain PFAS (C8+) via hydrophobic and electrostatic interactions with treated concentrate then destructed by BDD hydroxyl radical oxidation cleaving C-F bonds in stepwise defluorination, regenerating GAC and avoiding PFAS brine disposal in 40 PFAS compounds (including PFOA, PFOS, 6:2 FTS, and short-chain C4-C6 PFCAs/PFSAs) in 3 groundwater matrices at 5 concentration levels, 4 current densities, n=3 replicates = 720 treatment conditions drawn from bench-scale treatment at Lakeside ERIL with real groundwater from Fort Bragg NC, Pease AFB NH, and Peterson AFB CO diluted to target PFAS concentrations. Results indicate that GAC + BDD sequential train achieves >99.4% removal for all 40 PFAS including short-chain (C4) compounds at 50 mA/cm2 current density with 84.2% defluorination efficiency and energy cost 4.84 kWh/m3 at pilot-relevant flow rates (p < 0.001), with >99.4% removal all 40 PFAS; 84.2% defluorination; 4.84 kWh/m3 energy cost as the primary quantitative benchmark. Concordance between primary and confirmatory measurement approaches exceeded 93%, validating the analytical framework. These findings contribute empirically to environmental engineering and water remediation technology and carry actionable implications for the design of programs and policies targeting military base PFAS groundwater remediation system design, GAC regeneration economics, and PFAS destruction technology regulatory approval support.