Phasing Out PFAS Isn’t Just Chemistry, It’s Engineering

From reactor design to circularity and operability, the road to safer alternatives depends on the overlooked expertise of process and chemical engineers.

PFAS are everywhere. They are in our water, our food packaging, our firefighting foams. As regulations tighten and companies search for alternatives, the conversation has been dominated by chemists developing new molecules and by environmental scientists tracking contamination. These roles are vital, of course. But there’s a third, often overlooked pillar of this transition: the engineers who make it all work at scale.

I’ve been talking to many engineers who spent their career in process and chemical engineering, working at the boundary between lab discovery and industrial application. What I see, over and over, is a public discussion that underestimates how much work is required to make new materials not just viable in principle but usable in practice. Process engineering is the bridge between invention and implementation. Without it, even the most promising PFAS-free chemistry can fall apart before it ever leaves the pilot stage.

Start with synthesis. Chemists identify new structures that avoid the persistence and toxicity of PFAS. But these molecules don’t make themselves. We design the reactors, the flow paths, the separation steps, and the energy balance to actually produce them. A greener solvent may work in a small round-bottom flask. But can it perform under pressure in a continuous flow system? Will it require new materials for reactor linings? How will it interact with catalysts over long production cycles?

Catalyst performance, for example, is often studied in lab conditions that don’t reflect the chaos of real-world operations. A catalyst might function well for a few grams of material but degrade quickly under high throughput, where pressure, fouling, and temperature gradients introduce entirely new behaviors. Our role is to test, adapt, and engineer systems that maintain yield and purity over long production runs. Without this, the cost of manufacturing new alternatives can quickly become prohibitive.

In some cases, we are even rethinking where and how chemicals should be made. Instead of relying on large, centralized facilities that store and transport hazardous intermediates, we are exploring modular, distributed manufacturing. Smaller units located closer to the point of use can reduce logistical risks, respond more flexibly to demand, and avoid building massive new infrastructure for every new product.

Beyond synthesis, we confront one of the hardest challenges in phasing out PFAS: achieving the same performance in complex, multiphase systems. PFAS are not just chemically durable. They excel at managing interfaces, reducing surface tension, stabilizing emulsions, and enabling difficult processing steps. Replacing these functions is not a matter of swapping in a new ingredient. It requires a fundamental redesign of how fluids mix, how layers interact, and how surfaces are treated.

Take firefighting foams or industrial coatings. The physical behaviors of these products depend on precise control of viscosity, surface energy, and evaporation rate. To match that performance, we must design new flow regimes, reconsider order of component addition, and implement tighter process control at every stage. Small differences in mixing speed or thermal ramp rate can mean the difference between a viable foam and a useless one.

In manufacturing, many PFAS are used as processing aids. They reduce friction, improve flow, or stabilize dispersion in systems that would otherwise clog or degrade. Finding alternatives means more than changing the recipe. It may require redesigning extruders, adjusting die temperatures, or developing new surface treatments for handling equipment. These are deep, systemic interventions that extend far beyond chemistry.

Then comes the question of end-of-life. The conversation around PFAS-free design often stops once the product is made. But engineers must consider what happens when that product reaches the end of its useful life. Can it be disassembled, separated, and recycled? Can its by-products be valorized instead of discarded?

Designing for circularity is not a slogan. It means building separation processes that can isolate useful materials from complex mixtures. It means tracing contamination risks across cycles and ensuring quality control in recycled streams. And it means treating wastewater, even from PFAS-free processes, in ways that prevent the emergence of new persistent pollutants.

Safety is another layer. New chemistries bring new hazards. A compound that is benign under lab conditions might become unstable when heated, compressed, or exposed to impurities. We must assess not only intrinsic toxicity but also flammability, reactivity, and explosion potential under real manufacturing conditions. Our job is to design systems that can handle these uncertainties safely, reliably, and with clear margins of control.

And finally, supply chains. Every new chemical needs raw materials. Where do they come from? Are they available at the scale needed for industrial adoption? What new purification or quality control steps will be required? These are not footnotes. They are often make-or-break issues that determine whether a PFAS-free alternative can scale quickly enough to meet demand.

All of this illustrates a central truth. Chemists tell us what’s possible. Environmental scientists tell us what’s at stake. But engineers define what’s practical. We translate theory into application. We ask not just whether something can be done, but whether it can be done well, done safely, and done affordably.

So if we are serious about moving beyond PFAS, we need to stop treating engineering as an afterthought. It is not the final step in the process. It is the framework that determines whether the transition succeeds or stalls. Our work happens mostly out of view. But without it, the path to a PFAS-free future is just that no one can walk!