A full-scale trial was conducted at a GAC reactivation facility in the U.S. to evaluate the effectiveness of thermal reactivation for destroying per- and polyfluoroalkyl substances (PFAS) adsorbed onto spent granular activated carbon. The spent GAC, sourced from PFAS-impacted water treatment, contained measurable levels of targeted PFAS compounds.
The facility uses a multihearth Herreschoff furnace with a downstream emissions abatement system comprising a thermal oxidiser, spray quench cooler, dry injection scrubber, and baghouse. Samples of all inputs and outputs were analysed for targeted PFAS and fluoride (both total and hydrogen fluoride), using high-resolution mass spectrometry and fluoride ion-selective electrodes. Results showed >99.99% destruction of PFAS, with complete removal from the spent GAC. Most PFAS destruction occurred in the furnace before the thermal oxidiser. The fluoride mass balance indicated 61.4% recovery, suggesting conversion of PFAS to fluoride compounds.
Emissions from the system were significantly lower than those reported for PFAS manufacturing sites. The study confirms that thermal reactivation under standard operating conditions can effectively destroy PFAS in spent GAC, supporting continued reuse of reactivated carbon while managing PFAS risks.