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What an EO Pilot Test Actually Needs to Prove

A pilot that runs clean and looks good in a summary slide isn’t automatically a pilot that told you what you needed to know. This is the protocol-level detail — sampling frequency, run duration, what to log and when — that separates a usable dataset from a nice-looking one.

Protocol requirements drawn from electrochemical oxidation pilot and treatability-study practice. Methodology and review note near the bottom of this page.

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The actual job of a pilot

What this test needs to prove

Before capital moves, a pilot has to answer four specific questions about your actual stream — not a published range, and not a bench result from one early-batch sample. Everything else in a pilot report is supporting detail. These four are what actually de-risk the capital decision, and they’re the four the rest of this page is built around.

Two stages, two different jobs

Bench-scale vs. pilot-scale: what each actually validates

The minimum protocol

What a valid test protocol actually requires

  • A representative sample — a composite collected over several days or production cycles, not a single grab sample that happens to be convenient to ship
  • A current density sweep, not a single fixed setting — you need the relationship between current density and efficiency, not one point on it
  • Run duration long enough to reach the mass-transport-limited region as COD depletes — stopping at the early high-efficiency window overstates performance
  • Temperature and pH tracked throughout — both drift during a run and both affect current efficiency and byproduct formation
  • Byproduct sampling at defined intervals, not just at the end — formation rate over time matters as much as the final concentration
  • At least one replicate run — wastewater composition varies batch to batch, and a single run can't distinguish real performance from batch-to-batch noise

What to measure, and how often

The measurement schedule

  • COD or TOC — at regular intervals through the run, frequently enough to plot a real removal curve, not just start and end points
  • Cell voltage — continuously or at short fixed intervals, since a rising trend at constant current is the earliest signal of fouling or scaling
  • Current and charge passed — needed to calculate actual current efficiency against theoretical (Faradaic) removal, the number that tells you how much of your electricity is doing useful work
  • Chlorate and perchlorate — at the start, midpoint, and end of the run on any stream with meaningful chloride content, not only if something looks wrong
  • pH and temperature — logged alongside every other measurement, since both are process variables here, not just conditions to note in passing

Where pilots go wrong

Five mistakes that produce an unusable dataset

A run stopped after an hour, while COD is still high and current efficiency is at its best, produces a specific energy consumption number that will never survive contact with a full batch cycle. The number that matters is the average across the whole run, not the best moment in it.
Wastewater composition shifts with production schedule, shift changes, and cleaning cycles. A pilot run on one grab sample tells you how that one sample behaved — not necessarily how your stream behaves.
Strong COD removal and clean byproduct behaviour are two separate outcomes, not one. A run that never checked for chlorate or perchlorate hasn’t ruled out a problem — it’s simply never looked for one.
A single operating point tells you that point worked — it doesn’t tell you where efficiency starts collapsing, which is exactly the information a full-scale design needs to avoid running past that point continuously.
Fouling and scaling trends that look flat over a two-day pilot can turn upward well before a full year of continuous operation. A short pilot can flag an obvious problem, but it can’t confirm electrode service life on its own.

The output that actually supports a capital decision

What a usable dataset looks like when you're done

  • A specific energy consumption curve — kWh per kilogram of COD removed, plotted against concentration or time, not a single average number
  • A byproduct formation table — chlorate and perchlorate concentration at each sampling point, against current density and run duration
  • A cell voltage trend over the full run — flat, rising, or accelerating, with enough data points to tell which
  • A current-efficiency-vs-current-density curve — the basis for choosing a full-scale operating point that doesn't sit past the mass-transport-limited knee
  • A written recommendation on electrode material, current density range, and residence time for full-scale design, tied directly to the data above
That’s the dataset a go/no-go decision on capital should actually rest on — not a single “it worked” summary slide. Treat it as the engineering record behind the decision: final sizing and purchase specs still deserve a review from a licensed process engineer before capital gets committed.

Methodology and review

Where this protocol comes from, and who checked it

The four proof points, the six-item minimum protocol, and the measurement schedule above reflect what a process engineer actually checks in a pilot report before recommending capital release — not a generic testing checklist. Run duration, replicate requirements, and byproduct sampling intervals are set to catch the two failure modes that show up most often in vendor-run pilots: stopping the run during the early high-efficiency window, and treating COD removal as the only outcome that matters. Regulatory limits for chlorate and perchlorate are not included here because they vary by jurisdiction and discharge point — confirm the applicable number against your current permit before finalizing a sampling plan.

Methodology reviewed by [Reviewer name, P.E. — credentials/title]. Last technical review: [Month Year]. If the protocol requirements or measurement schedule are updated, this note and the review date should be updated to match.

Straight answers

Common questions

Long enough to see current efficiency decline as concentration falls, and long enough to see a real cell-voltage trend rather than a flat first few hours. That’s typically measured in weeks rather than days for a pilot, though bench-scale screening can be shorter.
It’s possible on a very well-characterised stream with strong bench data and a small, low-risk system, but it removes the step that validates cell design, flow pattern, and sustained electrode performance — for anything beyond a small system, that’s usually a risk worth avoiding.
Either can, but if a vendor runs it, ask for the raw data — the full concentration curve, voltage trend, and byproduct results — not just a summary report. The raw data is what lets you or an independent engineer verify the conclusions rather than take them on faith.
Yes, and they vary by jurisdiction and by whether the effluent goes to a POTW or a direct discharge. Pull your current permit or pretreatment agreement before the pilot starts, not after, so the byproduct sampling schedule gets checked against the number that will actually apply — not a general industry rule of thumb.
Not necessarily. Published ranges usually come from more favorable stream chemistry than yours. A worse-than-published energy number changes the economics, not automatically the go/no-go — run the actual number through the feasibility assessment before deciding it rules EO out.

More questions? Explore  more

Where does this take you next?

Choose the path that matches where you are now, get a better comprehension about electrochemical oxidation wastewater treatment.

Haven't run this yet

Running this protocol correctly — current density sweep, replicate run, byproduct sampling on a fixed schedule — takes lab equipment and QA most facilities don’t keep in-house. That’s what a commissioned treatability study is built to cover.

Start Treatability Studies

Data holds up across the full run

Current efficiency, energy consumption, and byproduct results all support moving forward. Take that dataset into the feasibility assessment to size and cost a full-scale system.

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Data argues against EO

Efficiency collapsed early, byproducts ran high, or voltage climbed steadily through the run. Worth comparing EO against the alternatives before budgeting for a second pilot.

Compare the alternatives →
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