When discharge limits drive the schedule
A Michigan industrial facility needed a practical pump-and-treat path for historic per- and polyfluoroalkyl substances (PFAS) impacts in groundwater. Perfluorooctane sulfonate (PFOS) averaged 1,650 ng/L, well above the local publicly owned treatment works (POTW) discharge limit of 28 ng/L. The team also needed to control secondary waste. Sending large volumes off-site for disposal would add cost, extend timelines and increase handling complexity.
For industrial site leaders and operators, the starting conditions will sound familiar: a high-strength PFAS water stream, a hard discharge threshold and pressure to minimize residuals that require transport and disposal. The question was not whether to treat. It was how to treat efficiently while keeping downstream logistics manageable.
Designing for removal and residual minimization
The pilot used Onterris FOAM-X™ foam fractionation as an upstream concentration step ahead of PFAS destruction. The deployed skid was sized for 2–5 gallons per minute (gpm) and designed to create a stable foamy layer called foamate. In foam fractionation, engineered air injection selectively draws PFAS into the foam phase, separating it from the bulk water and concentrating it into a small residual stream.
To reflect how a full-scale continuous system would operate, the team ran a two-stage pilot on-site. Stage 1 focused on aggressive mass capture and Stage 2 served as a polishing step to consistently meet discharge requirements. Operators evaluated key parameters that affect performance and waste volume, including chemical additives, system flow rates and air injection rates. The goal was to balance three field realities at once: meet the 28 ng/L limit, maintain steady hydraulic throughput and produce the smallest practical foamate volume for downstream destruction.
The win here was not just hitting the number. It was aligning operations so the capture step and the destruction step stayed in sync, kept residuals contained on-site and made the whole loop run predictably.
Pairing concentration with on-site destruction
Foamate generated by the FOAM-X system was routed to a co-located PFAS destruction unit using photo-activated reductive fluorination (PRF). That pairing is the core operational insight for landfill applications: foam fractionation performs best when it is treated as the front-end concentrator, reducing the volume that the destruction system must handle while keeping PFAS mass in a controlled pathway.
The destruction unit processed the concentrated foamate and returned the treated effluent back to the head of the FOAM-X system. This closed-loop configuration avoided accumulating a PFAS-laden waste stream that would require off-site disposal, turning the combined setup into a practical treatment and destruction train rather than two disconnected processes.
Results that translate to industrial site decision-making
Across the pilot, Onterris treated approximately 43,232 gallons of PFAS-impacted water and achieved PFOS bulk removal greater than 99.8% by mass. Effluent concentrations dropped below the 28 ng/L discharge limit, with Stage 2 reaching non-detect. The system also averaged an approximately 1300x concentration factor, sharply reducing the residual volume sent to destruction.
On the destruction side, the PRF unit achieved greater than 99.7% destruction of concentrated PFOS mass. With the effluent returned to the treatment headworks, the integrated approach generated no PFAS waste requiring off-site disposal during treatment.
Today, this project stands as a field-ready model for sites facing PFAS discharge constraints and limited appetite for hauling residuals. It also reinforces a scalable strategy for processed water programs: use foam fractionation to concentrate PFAS efficiently, then route a minimized residual stream into a compatible destruction technology sized for the real-world footprint and flow needs of the facility.
