Rapid Removal of Poly- and Perfluorinated Compounds from Investigation-Derived Waste (IDW) in a Pilot-Scale Plasma Reactor

Abstract

A pilot-scale plasma reactor installed into an 8 × 20 ft 2 mobile trailer was used to rapidly and effectively degrade poly-and perfluoroalkyl substances (PFAS) from liquid investigation-derived waste (IDW; development and purge water from monitoring wells) obtained from 13 different site investigations at Air Force installations. In the raw water, numerous PFAS were detected in a wide concentration range (∼10−10 5 ng/L; total oxidizable precursors (TOP) ∼10 2 −10 5 ng/L, total fluorine by combustion ion chromatography ∼10 2 to 5 × 10 6 ng F/L). The concentration of total PFAS (12 perfluorocarboxylic acids (PFCAs) and perfluoroalkyl sulfonates (PFSAs)) in the 13 samples ranged between 2.7 and 1440 μg/L and the concentration of perfluorooctane sulfonate (PFOS) plus perfluorooctanoic acid (PFOA) ranged between 365 and 73700 ng/L. Plasma-based water treatment resulted in rapid perfluoroalkyl acids (PFAAs) removal from 4 L individual IDW samples with faster rates for longer-chain PFCAs (C ≥ 8) and PFSAs (C ≥ 6) than for PFCAs and PFSAs of shorter chain length. In 9 of the 13 IDW samples, both PFOS and PFOA were removed to below United States Environmental Protection Agency's (USEPA's) health advisory concentration level (HAL) concentrations in <1 min, whereas longer treatment times (up to 50 min) were required for the remaining four IDW samples due to either extremely high solution electrical conductivity, which decreased the plasma−liquid contact area (one IDW sample) or high concentrations of PFAAs and their precursors; the latter was found to be converted to PFAAs during the treatment. Overall, 36−99% of the TOP concentration present in the IDWs was removed during the treatment. There was no effect of non-PFAS co-contaminants on the degradation efficiency. Overall, the results indicate that plasma-based water treatment is a viable technology for the treatment of PFAS-contaminated IDW.

Review on discharge Plasma for water treatment: mechanism, reactor geometries, active species and combined processes

“…The process was competitive with industrial habitual chemical proceedings [152]. On the other hand, this technology has shown high efficacy in the degradation of trace organic compounds such as pharmaceuticals at a pilot-scale [153], or for the degradation of wide concentration range (~10-10 5 ng/L) of poly-and perfluoroalkyl species from liquid investigation-derived waste [154]. A supplementary ozone injection in pilot scale plasma system for some organic pollutants removal has proved to be more efficient [155].…”

Combustion ion chromatography for extractable organofluorine analysis

“…A combination of high sensitivity, low cost (compared with, e.g., ICP-MS/MS), and simple operation has resulted in CIC becoming a go-to method for EOF analysis. The use of CIC for fluorine content analysis in environmental samples has become more widely used, and different in-house quality control (QC) routines have been reported ( Schultes et al., 2018 ; Singh et al., 2019 ; von Abercron et al., 2019 ). The QC samples could contain a different form of fluorine from the calibration samples ( Yeung et al., 2008 ; Yeung et al., 2009 ; Yeung and Mabury, 2016 ; von Abercron et al., 2019 ), or information regarding QC is lacking ( Singh et al., 2019 ).…”

“…The use of CIC for fluorine content analysis in environmental samples has become more widely used, and different in-house quality control (QC) routines have been reported ( Schultes et al., 2018 ; Singh et al., 2019 ; von Abercron et al., 2019 ). The QC samples could contain a different form of fluorine from the calibration samples ( Yeung et al., 2008 ; Yeung et al., 2009 ; Yeung and Mabury, 2016 ; von Abercron et al., 2019 ), or information regarding QC is lacking ( Singh et al., 2019 ). The use of IF standard solutions to calibrate the system for EOF analysis hinges on the assumed 100% combustion efficiencies of OF compounds.…”

Understanding and Managing the Potential By‐Products of PFAS Destruction

“…The alternative approaches are emerging as more mobile options using small‐scale plants, which could be applied at sites where PFAS waste concentrates are generated. Based on numerous sources, an approximate range of energy demand per volume treated for plasma, electrochemical treatment, and sonolysis is 0.01 to 0.5‐kW h per liter (kW‐h/L; 0.04 to 1.9 kW‐h per gallon [kW‐h/gal]; e.g., Gomez‐Ruiz et al ; Soriano et al ; Kempisty et al ; Nzeribe et al ; Singh et al , ). However, approximating a range of energy demand for these relevant technologies is difficult to accurately summarize due to the variety of operating conditions within the respective studies when the energy demand was determined.…”

“…Residence times associated with PFAS destruction are believed to approximately range from 30 min to 8 h (e.g., Mader et al ; Mitchell et al ; Gomez‐Ruiz et al ; Bentel et al ; Nzeribe et al ; Singh et al , ). The broad range of residence times provided represents the different applications reported in the literature and varies according to the targeted destructive mechanism, the influent PFAS concentration, the geochemistry of the treated matrix, and the targeted degree of defluorination.…”