EO Level 1 · Decision gate: Treatability Study
Is Electrochemical Oxidation Right for Your Wastewater?
Four numbers from a lab report do most of the deciding here — BOD:COD ratio, COD concentration, chloride, and whatever limit you actually have to hit. This specific page is a filter, not a pitch: work through it and you land on one of three next steps, not a demo request, what is more we never do things we can not accomplish, what is more, electrochemical oxidation is not “jack of all trades”, so explore what can electorchemical oxidation can do, and we are gonna be honest all the time.
How to use this page
What this gate decides — and what it doesn't
This is the entry point to our whole electrochemical oxidation knowledge base, and it does one job: sort your stream into GO, NOT SURE, or NO before you spend a week comparing vendors or a cent on a pilot skid. It does not size a reactor, pick an anode, or quote a system — that work happens downstream, once the fit question is answered.
We’ve commissioned electrode stacks against pulp mill condensate, textile dye baths, landfill leachate and a handful of streams that read well on a spec sheet and failed on a bench test for reasons the spec sheet never mentioned. The thresholds below come from that record, not from a datasheet. Treat every number as a starting point for your own lab work, not a substitute for it — and if a discharge permit is involved, run the final call past whoever holds compliance sign-off at your facility, not past this page.
The hard constraints
The four numbers that decide fit
BOD:COD under roughly 0.3
Run EO where biology has already given up. A BOD:COD ratio below about 0.3 signals a refractory organic load — the fraction the hydroxyl radical was built to break. Above that line, aeration beats EO on cost per kilogram of COD removed almost every time.
COD in a workable concentration band
Most published pilot work sits in a 500–5,000 mg/L COD range. Below that band, current efficiency collapses — there isn't enough substrate at the electrode surface to justify the amperage, and you end up paying for oxygen evolution instead of pollutant destruction.
A chloride number you've actually checked
Above roughly 1,000–2,000 mg/L chloride, active-chlorine and BDD-driven pathways start pushing conversion toward chlorate and perchlorate. That's a permit risk to design around before day one, not a footnote for after a compliance letter arrives.
A named limit, not a wish
Projects that close have a number: a COD limit, an AOX limit, a colour spec, an EC50 toxicity threshold, or one flagged compound. "Cleaner water" without a target is how a pilot runs forever and a budget never gets approved.
The second-order factors that still swing the answer
- Conductivity high enough to carry current, or a supporting electrolyte you can afford to dose continuously
- Flow pattern — a steady industrial discharge sizes very differently than a batch dump twice a shift
- Site power — whether the rectifier load fits your existing supply or needs new switchgear
- Unattended run time you actually need, and who on staff can read a cell-voltage trend
- Whether an equalisation tank already exists, since EO performs far better on a levelled feed than a raw spike
None of these five disqualify a stream on their own — they change the design, not the verdict. A low-conductivity stream can still work with a modest electrolyte dose; a batch process can still run through EO with the right tankage in front of it.
What they do is move a borderline chemistry result from a clean GO to a NOT SURE, because the answer now depends on a cost trade-off specific to your site rather than on the chemistry alone. That’s exactly what the feasibility and compatibility tools further down this page are built to resolve.
Underneath this gate
The five clusters this decision routes to
Before the full checklist
Run the 90-second version yourself
- BOD:COD is under roughly 0.3, or biological treatment has already stalled on this stream
- COD sits in the 500–5,000 mg/L range, not a dilute rinse or a raw high-strength dump
- Chloride is below the level where chlorate/perchlorate becomes a permit problem — or you're prepared to manage it by electrode choice
- You have a named limit: a COD number, an AOX number, a colour spec, or a flagged compound
- Conductivity supports current flow without an electrolyte dose you can't sustain
- Someone on your team can commission and read a bench or pilot trial before capital is committed
Why fit decisions go wrong
Five mistakes that show up as a bad fit decision
Positioning, not promotion
What EO actually replaces
Here at Evoaeo, we won’t pitching eletrochemical oxidation technology as “one for all”, that is: If the answer to this gate is GO, this is what you’re actually adding to your train — not a general-purpose treatment plant.
A polishing step, not a plant
Sits after biological or physical treatment to finish what those stages can't touch — the last slice of refractory COD, colour, or a named toxic species.
Refractory organics biology won't eat
PFAS precursors, certain dyes, pharmaceutical residues and other structures that pass through activated sludge intact.
A compliance step ahead of discharge
Where a permit limit — not a general desire for cleaner water — is the actual driver of the project.
One stage in a longer train
Paired with equalisation, clarification, or membrane polishing rather than run as a solitary process.
The actual gate
Where this decision goes next
GO — the chemistry supports EO
BOD:COD is low, COD sits in a workable band, chloride is manageable, and you have a number to hit. The next step is sizing a real trial, not another comparison.
NOT SURE — a number is missing
Most streams land here on the first pass, usually because chloride, conductivity, or a target limit hasn't been pinned down. Work the full checklist before ruling anything in or out.
NO — a different technology fits better
High BOD:COD, dilute bulk flow, or municipal-scale volume usually means biological treatment, ozonation, or membrane filtration hits the same target for less money.
Straight answers
Common questions about this fit decision
Why trust this gate
Built from commissioning records, not a data sheet
The thresholds on this page came from stack commissioning work — pulp and paper condensate, textile dye baths, landfill leachate, and streams that read well on a spec sheet and failed on a bench test for reasons the spec sheet never mentioned. That’s a different starting point than a comparison chart built from published papers alone.
None of it replaces your own process engineer, and none of it should be the sole basis for a capital decision. Where a discharge permit or an environmental approval sits behind the project, get the final call signed off by whoever holds that compliance responsibility at your facility — this page gets you to the right conversation faster, not around it.