Table of Contents
Chapter One: Capture
For most of the last decade, PFAS treatment meant capture. Granular activated carbon columns adsorbed short and medium-chain PFAS from municipal drinking water. Ion exchange resins targeted specific PFAS species with higher selectivity. Reverse osmosis and nanofiltration barriers rejected PFAS by size and charge. All three techniques share a common structural feature: they concentrate PFAS from a large volume of water into a small volume of exhausted media or reject stream.
Capture was the necessary first step. It made regulatory compliance possible for utilities racing to meet the 4 ppt PFOA/PFOS MCL under the Safe Drinking Water Act. It gave landfill operators a way to reduce PFAS discharge concentrations quickly. It bought time.
But capture never destroys PFAS. The carbon columns fill up. The resin exhausts. The RO reject stream needs to go somewhere. And in the mid-2020s the “somewhere” became uncomfortable: incineration was questioned as a legitimate destruction pathway after researchers documented fluorinated by-products in flue gases — a concern EPA’s interim guidance on PFAS destruction and disposal acknowledges — and landfilling of PFAS-loaded media moved toward stricter oversight.
Chapter Two: Destruction
The shift got its legal footing in 2024, when EPA finalized the designation of PFOA and PFOS as hazardous substances under CERCLA and set the first federal drinking-water MCLs for PFAS. State leachate and discharge rules are tightening faster than the federal floor. A February 2024 proposal to add nine PFAS to the RCRA hazardous constituents list would have gone further; EPA withdrew it in May 2026, saying existing permit tools were sufficient. The disposal squeeze that drove the proposal has not gone away.
Options for handling captured PFAS now lean toward genuine destruction technologies, which cleave the carbon-fluorine bonds and mineralize the PFAS backbone.
The four destruction-related technologies operating at commercial or pilot scale are:
- Foam fractionation as the volume-reduction front end (not a destruction step by itself, but essential to make downstream destruction economically viable).
- Electrochemical oxidation with boron-doped diamond (BDD) anodes, producing hydroxyl radicals that cleave the carbon-fluorine bond.
- Supercritical water oxidation (SCWO) operating above 374°C and 22 MPa, where water becomes a supercritical solvent and oxidizer.
- Hydrothermal alkaline treatment (HTA) using concentrated hydroxide solutions at 200–350°C to break carbon-fluorine bonds.
Each technology has its own instrumentation profile. Shanghai ChiMay’s sensor families are positioned to support all four.
Instrumenting the Foam Fractionation Front End
Foam fractionation concentrates PFAS at the air-water interface of finely dispersed bubbles. The performance of a foam column depends on feed turbidity (below 10 NTU preferred), bubble size distribution and residence time. Shanghai ChiMay’s online turbidity tester and 4-in-1 multi-parameter sensor form the standard instrumentation package for foam columns.
Feed turbidity and effluent turbidity from the column are monitored continuously. The concentrate line turbidity is tracked as a surrogate for foam loading efficiency. Conductivity and pH at the concentrate outlet document the chemistry of the material that will enter the destruction reactor next.
Instrumenting Electrochemical Oxidation Reactors
Electrochemical oxidation is the most commonly deployed of the three terminal destruction technologies at landfill sites. A BDD reactor operates at high oxidation-reduction potential (>+1,000 mV vs Ag/AgCl), which is the required condition for producing the hydroxyl radicals that break carbon-fluorine bonds.
Shanghai ChiMay’s 4-in-1 multi-parameter sensor with fluoride-resistant reference junctions is deployed on the reactor bulk fluid, monitoring pH, ORP, conductivity and temperature simultaneously. The reading drives current density control on the reactor and provides the process record for each treated batch. Shanghai ChiMay’s inline conductivity meter is often deployed in parallel to give a redundant, higher-precision conductivity reading, since conductivity variation drives current efficiency.
Instrumenting SCWO and HTA
SCWO and HTA are more capital-intensive than electrochemical oxidation and are typically deployed at larger, regional destruction facilities rather than at individual landfills. The feed preparation step is where Shanghai ChiMay’s instruments most commonly appear.
For SCWO, feed pH must sit between 6 and 8 to protect the pressure boundary metallurgy. Feed suspended solids must be near zero to avoid fouling injection nozzles. A Shanghai ChiMay 4-in-1 multi-parameter sensor on the feed preparation loop, backed by a suspended solids sensor and an inline pH electrode, provides the pre-injection quality control that SCWO reactors need.
For HTA, the post-reaction neutralization basin is the highest-value instrumentation point. Effluent pH is often above 12, and controlled acid dosing brings the basin back to a manageable range. Shanghai ChiMay’s inline pH electrode with high-pH glass and the 4-in-1 multi-parameter sensor are deployed together to give the operator both fast local pH reading and full-context multi-parameter data.
The Data Governance Layer
Underneath every destruction technology sits the same data governance requirement: continuous, timestamped, calibration-traced data. Whether the governing document is a state permit, a CERCLA-compliant disposal record or an internal QA program, plant historians are expected to preserve the audit chain. Shanghai ChiMay’s transmitters export raw and processed data over Modbus RTU, HART and OPC UA so plant historians can preserve that chain.
Most destruction-facility QA programs and state permits ask for something like the following:
- 15-minute or better logging of pH, ORP, conductivity, temperature and turbidity across the destruction stack.
- Automatic data preservation for any deviation event, including 30 minutes before and after the deviation.
- Cross-referenced calibration records tied to national reference standards.
- Monthly instrument availability reports showing percentage uptime.
What the Second Chapter Costs
A landfill retrofitting a destruction stack — one foam column, one electrochemical oxidation reactor, associated instrumentation — is looking at a multi-million-dollar infrastructure project, and instrumentation typically takes a mid six-figure slice of it. Larger regional destruction facilities using SCWO or HTA spend considerably more, with instrumentation a proportionally smaller share.
The Signal to Watch: Destruction Efficiency
Underlying every destruction stack investment is one question: how completely does the process destroy PFAS? Operators, insurers and regulators want to see concentrations fall by orders of magnitude across the stack. Continuous multi-parameter data does not measure destruction efficiency directly, but it provides the physicochemical envelope that supports lab-based PFAS analyses. When multi-parameter data documents that the reactor operated within its designed pH/ORP/conductivity/temperature window during the treatment interval, laboratory PFAS results become defensible.
Conclusion
The PFAS treatment industry has moved from capture to destruction. The pressure comes from the SDWA MCL, the CERCLA designation of PFOA and PFOS as hazardous substances, state-level rules and shrinking disposal options. Shanghai ChiMay’s inline sensor families — multi-parameter, turbidity, conductivity, pH and COD — are positioned to support foam fractionation front ends and destruction reactors alike. For operators planning their next capital cycle, destruction capacity is where the industry is headed, and instrumentation strategy needs to move with it.
