PRD Efficacy and Site-specific Cost for PFAS Destruction in Surface Water Concentrate
Enspired Solutions evaluated our novel technology, photoactivated reductive defluorination (PRD), for PFAS destruction in surface water foamate. This work was done at the request of a state regulatory agency.
Objectives addressed in a bench-top treatability test were 1) Demonstrate PRD efficacy on PFAS in a sample of surface water foamate, and 2) Provide a site-specific cost projection for the destruction of 99.9% PFAS in 50 gallons per day of foamate.
PRD Efficacy on PFAS Concentrate
PRD effectively destroyed PFAS during the test; concentrations of PFAS decreased by up to five orders of magnitude. Results are presented in Figure 1, focused on the proposed EPA Maximum Contaminant Level (MCL) list of six PFAS (PFNA, PFOA, PFOS, PFHxS, PFBS, and HFPO-DA), and discussed in terms of applied ultra-violet light (UV) dose.
Four PFAS were detected in the untreated foamate sample (0 kWh/m3) and the combination of PFOA and PFOS accounted for 95% of total PFAS. All PFAS were degraded by 99% or more within 800 kWh/m3 applied UV dose. From 800 to 5,400 kWh/m3 cumulative UV dose, concentrations decreased by an additional 1-2 orders of magnitude. Overall, PRD reduced the total EPA MCL PFAS concentration in the foamate from 4,000,000 ng/L to 320 ng/L, or by over 99.99%.
Site-Specific Cost Projection
PRD technology efficiency is optimized by destroying two to three orders of magnitude (99-99.9%) of concentrated PFAS and re-circulating destruction effluent for ongoing separation & concentration. Further discussion of this recirculating process model and our Destruction Process Basics can be found on elsewhere on our website. This model was used to project site-specific energy use and destruction cost.
Electrical energy per order of magnitude PFAS destruction (EEO), the key parameter to determine energy usage for destruction, was estimated based on direct energy usage measured during benchtop testing. EEO was then used to calculate estimated cost (CAPEX and OPEX) for field-scale application of the PFASigator™, our commercial-scale PFAS destruction unit.
For this site, the cost for destroying 99.9% of the EPA MCL-listed PFAS in foamate at a flow rate of 50 gallons per day (GPD) into the PFASigator™ was estimated at $ $3.91/gallon (Table 1).