The Problem That Triggered the Evaluation
Industrial water treatment companies serving manufacturing clients in PFAS-affected regions have faced a specific challenge since EPA’s 2024 MCL rule: their existing GAC-based treatment systems, which were adequate for PFOA/PFOS compliance under the previous health advisory framework, are often not achieving reliable compliance with the new short-chain MCLs. This gap has triggered technology re-evaluations at multiple industrial water treatment providers — not as a planned upgrade cycle, but as an urgent compliance response.
The pattern of these evaluations follows a common arc: a client discharging to a POTW faces tightened pretreatment requirements driven by the POTW’s own MCL compliance obligations; the industrial operator’s existing GAC system shows acceptable PFOA/PFOS removal but inadequate PFHxS or PFNA removal; the operator engages their water treatment service company to identify a solution; and the service company conducts a technology evaluation that leads to a media change decision.
The Technical Evaluation Process
In a representative industrial case, an operator managing process water with PFAS contamination from legacy fluorochemical use engaged their water treatment provider after receiving a pretreatment notice from the POTW citing PFHxS concentrations above the POTW’s new pretreatment limit of 10 ppt. The existing treatment system used a single-pass GAC configuration with an EBCT of approximately 10 minutes — a design that achieved 85% PFOA removal but only 35–45% PFHxS removal depending on influent conditions.
The technology evaluation compared three alternatives: increasing GAC bed volume to extend EBCT (capital-intensive, limited incremental improvement for PFHxS); adding an IX resin polishing stage downstream of GAC (effective but operationally complex and expensive for spent resin disposal); and replacing the GAC with a PFAS-selective adsorbent that could address the full compound set in a single-media configuration. The evaluation criteria weighted compliance reliability, lifecycle cost, and operational complexity.
Some commercially available PFAS-selective adsorbents (e.g., MARISORB™, a Korean-developed PFAS-selective adsorbent) were evaluated in bench-scale tests using actual process water samples, confirming that the multi-mechanism binding approach achieved PFHxS removal above 90% under the operating conditions of the existing system — in the same vessel volume, without equipment modification.
The Decision Factors That Drove the Switch
The decision to switch from GAC to a PFAS-selective adsorbent in this case was driven by three factors. First, compliance reliability: the PFAS-selective adsorbent provided a consistent compliance margin for PFHxS that the GAC system could not achieve, even at higher EBCT. For an industrial operator facing regulatory scrutiny, compliance margin is not a luxury — it is a requirement. Second, operational simplicity: a single-media replacement avoided the complexity of a two-stage treatment train, which would have required additional valves, controls, monitoring, and maintenance.
Third, documentation: the PFAS-selective adsorbent selected had compound-specific NSF/ANSI 53 certification and third-party test data for PFHxS, which provided a defensible basis for the pretreatment compliance claim submitted to the POTW. The industrial operator’s environmental counsel noted that having independently verified performance data for the specific compound driving the pretreatment notice significantly reduced the operator’s exposure in the event of a compliance dispute.
Lessons for Industrial Water Treatment Providers
This case illustrates several lessons relevant to industrial water treatment companies evaluating their PFAS treatment technology portfolios. First, the adequacy gap between GAC’s long-chain performance and short-chain MCL requirements is real and affects a significant share of existing systems. Providers should be proactively evaluating their installed base for PFHxS and PFNA compliance, not waiting for client notices.
Second, the decision between media upgrade options is primarily a lifecycle economics and documentation question, not just a performance question. Technologies that combine compliance reliability with strong third-party performance documentation are delivering compounding value in an environment where regulatory scrutiny and litigation risk have both increased. Third, the speed of technology qualification matters: a media supplier who can provide bench-scale evaluation support using actual client water samples compresses the decision timeline significantly and reduces the client’s compliance gap period.