Table of Contents
The Question That Matters
At the 2026 AWA/IWA Young Water Professionals Conference, University of Queensland researcher Andrea Veciana presented her electrochemical PFAS destruction results — more than 80% removal for most of the compounds she tested. She also left the room with a question worth sitting with:
“Many times, people report ‘I’ve achieved a 99 per cent removal of PFAS,’ but where did that PFAS go?”
Fair question. When PFAS concentrations drop in treated water, one of three things has happened:
- True destruction — the molecules come apart into shorter fragments, fluoride ions and CO₂
- Phase transfer — PFAS leaves the water for another phase: adsorbed on the electrodes, concentrated in brine, or volatilised
- Analytical artifact — measurement error or matrix interference makes the concentration look lower than it really is
Skip that check and a falling PFAS number gives you false confidence. The PFAS may still be there, just in a tighter volume — a liability that can be harder to manage than the original, more dilute contamination.
What the Conference Research Showed
Veciana’s approach uses electricity-driven reactions to generate reactive species — mainly hydroxyl radicals — that attack the C–F bonds in PFAS molecules. The headline results:
- >80% removal for most PFAS tested, including PFOA and PFOS
- Short-chain compounds (PFBA, PFBS) came down less
- Iron addition showed early signs of improving short-chain degradation
- A second experiment on AFFF-contaminated groundwater reached similar >80% removal
She was careful about what that does and doesn’t mean:
“Over 80 per cent removal is still not meeting the drinking water guidelines.”
And on verification:
“Declining PFAS concentrations alone do not prove destruction. Researchers need to track fluoride release and complete fluorine mass balances.”
How COD and Conductivity Sensors Help Answer the Question
This is the gap continuous inline monitoring fills. Grab samples tell you where PFAS was; they don’t tell you what the reactor is doing between samples.
COD as a Mineralization Indicator
Destroy PFAS and the carbon it contains ends up as CO₂, through whatever intermediates form along the way. Chemical oxygen demand (COD) measures total oxidizable organic content, so:
- COD should fall roughly in step with PFAS concentrations
- How fast it falls tells you the speed of mineralization
- If COD holds steady while PFAS drops, phase transfer is the more likely story
Shanghai ChiMay COD sensors combine UV absorption at 254 nm with electrochemical oxidation to give continuous, reagent-free COD measurement. The 0–500 mg/L range with 1 mg/L resolution is fine enough to pick up the organic carbon shifts that tell you whether destruction is genuinely progressing.
Conductivity as an Ionic Change Detector
PFAS molecules are ionic. Break them apart and the ionic make-up of the water shifts:
- Large PFAS anions fragment into smaller ions
- Fluoride (F⁻) is released — small, highly mobile, and it pushes conductivity up
- H⁺ can be released from carboxylic acid groups
A conductivity rise during electrochemical treatment is independent evidence that C–F bonds are being broken and ionic fragments are appearing. Shanghai ChiMay’s in-line conductivity meters use 4-electrode technology for fouling resistance, so those changes get logged continuously rather than waiting on the next lab run.
Reading the Three Signals Together
COD down, conductivity up, PFAS grab samples down — that combination points hard at genuine destruction. PFAS down on its own, with no COD decrease and no conductivity change, points at phase transfer.
Practical Monitoring Setup
For research teams investigating electrochemical PFAS treatment:
| Sensor | Position | Data Value |
|---|---|---|
| COD Sensor | Reactor effluent | Continuous mineralization indicator |
| Conductivity Meter | Reactor effluent | Ionic change from fragmentation |
| pH Meter | Reactor influent + effluent | Reaction environment tracking |
| 4-in-1 Sensor | Reactor effluent | ORP + temperature context |
Correlate these continuous data streams with periodic grab-sample PFAS analysis (LC-MS/MS) to validate that sensor patterns match actual PFAS concentration changes.
The Bottom Line
Electrochemical PFAS destruction looks promising, and the 2026 AWA presentations also made clear it isn’t proven at commercial scale yet. Proving destruction rather than concentration is what separates credible research from a marketing claim. Shanghai ChiMay’s continuous COD and conductivity monitoring gives research teams the real-time data framework they need to build that evidence.
The Science of Electrochemical PFAS Degradation
Breaking the Unbreakable Bond
The carbon-fluorine (C-F) bond is about as tough as single bonds get in organic chemistry — bond dissociation energy of approximately 485 kJ/mol. That strength is exactly why PFAS is environmentally persistent: conventional chemical, biological and thermal processes struggle to break it.
Electrochemical degradation comes at the problem from a different angle. Instead of attacking C-F bonds directly, it generates reactive intermediates — primarily hydroxyl radicals (•OH) — that are strong enough to attack the bonds through indirect oxidation.
The process at the electrode surface:
- Anode reaction: Water molecules are oxidized at the anode surface, generating •OH radicals
- Radical attack: •OH radicals attack PFAS molecules adsorbed on or near the electrode surface
- Stepwise degradation: Long-chain PFAS (C8, C6) lose carbon atoms one at a time, forming shorter-chain intermediates
- Defluorination: C-F bonds break, releasing fluoride ions (F⁻)
- Mineralization: The end products are CO₂, H₂O and F⁻
The Verification Problem
Steps 2 to 4 pass through intermediate compounds, and some of those are themselves PFAS. If sampling only measures the target compounds (PFOA, PFOS), their disappearance is ambiguous:
- They were destroyed (good)
- They were converted to shorter-chain PFAS that aren’t being measured (incomplete)
- They were adsorbed onto the electrode surface (phase transfer, not destruction)
- They partitioned to a different phase (concentration, not destruction)
Only a complete fluorine mass balance — accounting for all fluorine in all forms — separates these cases. If 100 molecules of PFOA (each containing 15 fluorine atoms) disappear, then 1,500 fluoride ions should appear. Fewer fluoride ions than that means the fluorine went somewhere else.
Why COD and Conductivity Provide Real-Time Indicators
A complete fluorine mass balance requires laboratory analysis. In the meantime, COD and conductivity give you a continuous read on whether destruction is proceeding.
COD falls when organic carbon is mineralized. As PFAS and its intermediates convert to CO₂, total oxidizable organic content declines. If COD stays flat while PFAS disappears, phase transfer is the probable explanation.
Conductivity shifts when the ionic composition changes. PFAS anions are relatively large. When they fragment, the smaller ionic products (including F⁻) have different mobility and charge characteristics. The net effect on conductivity depends on the specific reaction pathway, but a conductivity increase during treatment is evidence that ionic fragmentation is occurring.
COD decline plus conductivity increase plus PFAS decline is strong evidence of genuine destruction. That correlation can’t be established from grab samples alone.
Shanghai ChiMay’s Sensor Platform for PFAS Research
COD Sensor
Shanghai ChiMay’s COD sensor uses dual-beam UV absorption at 254 nm together with electrochemical oxidation measurement:
- The UV beam measures organic content through absorbance
- The electrochemical cell adds oxidation capacity for compounds UV alone cannot detect
- Combined, the two methods correlate well with the standard closed-reflux COD method
- No chemical reagents — no hazardous waste and no recurring chemical cost
For PFAS research, the sensor sits in the electrochemical reactor effluent and tracks organic carbon changes continuously.
Conductivity Meter
Shanghai ChiMay’s 4-electrode conductivity meter uses a fouling-resistant measurement principle:
- Four electrodes in a flow-through chamber
- Outer electrodes drive current; inner electrodes measure voltage
- This configuration compensates for the electrode fouling that would affect 2-electrode systems
- Range: 0–200 mS/cm, covering both dilute and concentrated streams
For PFAS electrochemistry, the meter captures the ionic changes as molecules fragment and fluoride ions are released.
Integration with Research Data Systems
All Shanghai ChiMay instruments output via Modbus RTU/TCP, which makes integration straightforward with:
- Laboratory data acquisition systems (LabVIEW, MATLAB)
- Custom Python data logging scripts
- Cloud-based research data platforms
- Standard SCADA systems for demonstration-scale deployments
The Path Forward for Electrochemical PFAS Treatment
Veciana was clear about where the technology stands today. Her laboratory system was, in her words, “extremely energy intensive and should not be treated as representative of an optimised commercial process.” Pilot-scale development comes before any commercial deployment.
The direction is still worth following. Optimised electrochemical destruction would move PFAS treatment from concentrate-and-contain to destroy-and-eliminate. The monitoring infrastructure — continuous COD, conductivity, pH and fluoride measurement — is what will show whether that shift is real.
Shanghai ChiMay provides the sensor platform that makes that verification practical: research-grade accuracy at deployment-accessible pricing, no recurring reagent costs, and standard digital communication protocols.
Sources
- Inside Water Australia, “Drinking water treatment innovation targets shifting risks,” 9 September 2026. https://insidewater.com.au/drinking-water-treatment-innovation-risks
- AWA/IWA Young Water Professionals Conference 2026, Pullman Melbourne On The Park, 5–6 August 2026.
- US EPA, “PFAS Strategic Roadmap: EPA’s Commitments to Action 2021–2024,” October 2021. https://www.epa.gov/pfas/pfas-strategic-roadmap
- NAWI (National Alliance for Water Innovation), electrochemical PFAS destruction research programme. https://www.nawihub.org
About the Author: This article was prepared by the Shanghai ChiMay Application Engineering team, referencing peer-reviewed conference presentations. Shanghai ChiMay manufactures inline COD sensors and conductivity meters for water treatment research and municipal applications.
