A new water-treatment process is said to be the first to comprehensively destroy per- and polyfluoroalkyl substances (PFAS) while also eliminating perchlorates. The PFASER technology, developed by WSP Global (Montreal, Que., Canada; www.wsp.com) is an advanced electro-oxidation (EO) treatment system that incorporates patented boron-doped diamond (BDD) electrodes developed by pro aqua Diamantelektroden Produktion GmbH (Niklasdorf, Austria; www.proaqua.at). “EO technology can effectively degrade PFAS onsite, at ambient conditions. The primary limitation is the formation of toxic byproducts, particularly perchlorate, which can occur when chloride ions in the water matrix are oxidized. The PFASER system integrates a proprietary and patent-pending perchlorate removal system that includes precise pH adjustment and hydrogen-peroxide dosing to prevent the formation of these toxic byproducts,” explains Valérie Léveillé, water treatment engineer at WSP Canada.
Like PFAS, perchlorates are persistent and hazardous, so Léveillé emphasizes that the PFASER system ensures that remediation efforts do not trade one contaminant for another: “Economically, the concurrent destruction of perchlorates and PFAS lowers operational costs and regulatory risk. By eliminating the need for additional treatment steps to address perchlorate formation, which is a common byproduct of standard EO, PFASER reduces the expenses and downtime associated with managing hazardous residuals, offsite disposal or further remediation.”
PFASER Unit (Source: wsp)
The PFASER system begins with pre-filtration, followed by the EO stage and a final granular-activated carbon polishing step to capture any trace contaminants. This blend of technologies has demonstrated over 99.999% perchlorate removal. The durable BDD electrodes utilized in the EO step enable the destruction of PFAS, along with other contaminants like ethanol, phenol, acetone, methanol and formaldehye. “The PFASER system also includes a self-cleaning feature to ensure consistent performance and efficiency of the BDD electrodes,” adds Léveillé.
WSP has demonstrated PFASER technology at the bench and pilot scales using groundwater, industrial wastewater, potable water and leachate, with a notable field application treating groundwater at a chemical manufacturing plant in the U.S. “During a two-month pilot, the system processed 9.6 m³ of contaminated groundwater per day, successfully treating both PFAS and perchlorate to achieve non-detectable levels, in compliance with regulatory requirements. These results were consistent across several batches, providing strong evidence of technical efficacy,” says Léveillé.
Two full-scale PFASER projects are currently pending: a 4-m³/day unit for treating airport groundwater, and a 30-m³/day unit at a semiconductor production facility.