Reducing or eliminating per- and polyfluoroalkyl substances (PFAS) in surface water can be a challenge as surface water systems are dynamic both in terms of flow and PFAS loading. Stormwater flows can be intermittent or several orders of magnitude higher than typical flow with the first flush carrying significant suspended solids that can clog filtration systems. Hence treatment systems that can adapt quickly to significant variations in flow rate, suspended solids, and PFAS loading are needed. The AquaStorm system was designed to meet these conditions in treatment applications for micronutrients and odor control using pile cloth media filters. This project will leverage the AquaStorm system along with the microsorbents that were demonstrated in ESTCP project ER19-5181 to attempt to meet the challenge of PFAS treatment in storm and surface water.

Reducing or eliminating per- and polyfluoroalkyl substances (PFAS) in surface water can be a challenge as surface water systems are dynamic both in terms of flow and PFAS loading. Stormwater flows can be intermittent or several orders of magnitude higher than typical flow with the first flush carrying significant suspended solids that can clog filtration systems. Hence treatment systems that can adapt quickly to significant variations in flow rate, suspended solids, and PFAS loading are needed. The AquaStorm system was designed to meet these conditions in treatment applications for micronutrients and odor control using pile cloth media filters. This project will leverage the AquaStorm system along with the microsorbents that were demonstrated in ESTCP project ER19-5181 to attempt to meet the challenge of PFAS treatment in storm and surface water.

The project will demonstrate the application of pile cloth media filtration (PCMF) with microsorbent addition to adsorb PFAS in surface waters and remove suspended sediments from surface water runoff. Testing will validate or determine the following:

• The technology’s ability to reduce low-concentration PFAS (< 500 ng/L) to USEPA MCLs
• The potential interaction between the polyester filter media and PFAS after prolonged exposure
• Sediment reduction capabilities achievable through filtration
• Capital and operational cost benefits as a potential alternative to current approaches
• Generation of a manageable waste stream that is amenable to approved disposal methods

Figure. Process Flow Schematic

Stormwater runoff will be conveyed through a coarse screen that removes larger debris followed by microsorbent dosing and mixing in a short-detention chamber. The small particle size of sorbents facilitates rapid kinetics keeping the dosing rate and required detention times low. The conditioned stormwater is then filtered by the PCMF system which provides three filtration zones: floatable zone where oils and grease are separated, filtration zone where solid with near-neutral buoyancy are captured by the PCMF, and bottom zone where heavy solids such as grits and large sediment particles get settled. The microsorbent is designed in a way that its specific gravity places it in the filtration zone, thus promoting further PFAS mass transfer to the microsorbent. The filter media is cleaned via automated backwashing followed by settling of solids which are taken for further thickening. The thickened solids can be managed via stabilization and disposal or destruction via DoD approved technologies. Backwash, the largest waste product, is typically 1 to 5% of the total influent, while the thickened solids are expected to fall below 1% of influent. The supernatant from solids thickening is returned back to the reactor.

Successful validation of the AquaStorm treatment system will provide a solution capable of managing variable flow, sediment, and PFAS concentration loading that creates cost and performance limitations for conventional approaches. Automated, adaptive operation will limit operational expenditures through waste segregation and volume reduction, while capital expenditures related to detention ponds could be reduced or eliminated due to operational flexibility. Results of this demonstration will enable development of design and implementation tools that will facilitate rapid deployment across a range of DoD installations. (Anticipated Project Completion - 2027)