Abstract: Methods and systems of PFAS destruction in water containing nitrate. The methods and systems include filtering water containing PFAS and nitrate through a membrane selective for PFAS to obtain a membrane reject containing PFAS and nitrate and a filtrate containing nitrate, forming a treatment solution using the membrane reject including diluting the membrane reject and combining the membrane reject with a photosensitizer, a sulfite salt, and a sufficient amount of base such that the treatment solution has a pH of about 10 or more, and irradiating the treatment solution with UV light in a photoreactor to destroy a portion of the PFAS. Before dilution, a concentration of PFAS in the membrane reject may be between about 3 times and about 20 times greater than before the filtering step. Dilution of the membrane reject may include between about a 3 and about a 20 times dilution.

Abstract: Methods, systems and devices for PFAS destruction including oxidatively pretreating an aqueous foam fractionate solution including PFAS to form a pretreated solution by mixing the aqueous foam fractionate solution with a persulfate and an acid or a base to increase or decrease the pH and oxidizing the aqueous foam fractionate solution and then subjecting the pretreated solution to UV photolysis, such as by directing UV light onto the pretreated aqueous foam fractionate solution at 222 nm, 254 nm and/or 185 nm. Oxidizing the foam fraction may include subjecting the aqueous foam fractionate solution to an increased temperature and pressure for a period of time sufficient for thermal oxidation or subjecting the aqueous foam fractionate solution to ozone oxidation.

Abstract: Methods, systems, and devices for PFAS destruction including providing water containing PFAS to a reactor vessel, irradiating the water with UV light under conditions to destroy at least a portion of the PFAS, passing the treated water through a selective membrane to form permeate and membrane reject comprising PFAS, providing the membrane reject back to the reactor vessel, providing additional water containing PFAS to the reactor vessel within the reactor vessel or before being provided to the reactor vessel, and irradiating the membrane reject and the additional water containing PFAS within the reactor vessel with UV light. The steps may be repeated a plurality of times such that PFAS that is not destroyed is recycled through the reactor vessel. Sensitizers may be added and may also be recycled in the membrane reject with the PFAS.

Abstract: Methods, systems and devices for PFAS destruction including removing nitrate from water containing PFAS, combining the water with a sensitizer and a sufficient quantity of base to create a treatment solution having a pH of about 10 or more, and irradiating the treatment solution with UV light in a photoreactor to destroy a portion of the PFAS. The nitrate may be removed electrolytically such as by electrolytically reducing nitrate to nitrogen gas and/or ammonia. The nitrate may be removed by filtration through a selective membrane, such as by reverse osmosis, forward osmosis, nanofiltration, and/or ultrafiltration. The system may include electrolytic cell system including a first cell with a cathode contacting the water containing PFAS in the first cell, a second cell including an anode in an electrolytic solution, a power source, and a salt brine and/or membrane separating the first and second cells.

Abstract: Methods, systems and devices for PFAS destruction including adding a sulfite salt to an aqueous solution containing PFAS and then irradiating the aqueous solution with light at 222 nm. The method may include adding a base to the aqueous solution in an amount sufficient to raise a pH of the aqueous solution including PFAS to about 10 or more. It may also include adding a halide salt such as a bromide salt or an iodine salt, and further adding a carbonate. Greater than 90%, or greater than 99%, of the PFAS in the solution may be destroyed by irradiating the aqueous solution in this way.

Abstract: Methods, systems and devices for photo-electrolyitic PFAS destruction including a photoreactor vessel configured to receive an aqueous solution including PFAS, a UV light source configured to direct UV light onto the aqueous solution in the photoreactor vessel, a cathode within the photoreactor vessel configured to contact the aqueous solution, an anode in an electrolyte solution, an electrical power supply configured to provide a voltage difference between the anode and cathode, and a membrane or ionic bridge between the anode and cathode. The cathode may be a mesh and may have a high surface area construction with an electrochemically active surface area that is greater than the geometric surface area.