How does electrochemical activation (ECA) work?

Electrochemical activation is a technology that looks complex but has extremely simple inputs: salt, water and electricity. A powerful disinfectant is produced from these three inputs, and no other chemical is required.

The basic principle: electrolysis

At the heart of the system is an electrolysis cell. A dilute salt (sodium chloride) solution is passed through this cell. When electricity is applied to the electrodes inside the cell, the water and salt molecules enter electrochemical reactions.

The chloride ions in the solution are oxidised at the anode and react with water to form hypochlorous acid (HOCl). The result is a solution with a low salt concentration but a high disinfecting power. At the cathode, water is reduced to hydrogen and hydroxide ions; together with the sodium ions in the solution, this forms sodium hydroxide (NaOH).

Diaphragm and non-diaphragm cells

ECA cells can be of two main types:

• Non-diaphragm (single cell): The anode and cathode are in the same chamber, so the products of both electrodes mix into a single solution.
• Diaphragm: The anode and cathode chambers are separated by a diaphragm, producing two distinct solutions: a hypochlorous acid-dominant oxidant (anolyte) on the anode side and a sodium hydroxide solution (catholyte) on the cathode side.

The Aquamirus E.C.A. system uses a diaphragm cell. Keeping the two products apart means the anolyte is not pushed toward the weaker hypochlorite form by hydroxide from the cathode, and the facility gains a second output: caustic that can be used on site for alkaline cleaning, CIP or pH correction, rather than being treated as waste.

Production to demand

The most important operating feature of ECA systems is that they can run to demand. The system starts and stops production automatically based on the free-chlorine measurement on the dosed line. As a result:

• Overproduction and over-dosing are prevented.
• The solution is always used fresh, with no shelf-life problem.
• Dosing is matched to the facility’s real-time need.

Why on-site generation?

In the traditional method, disinfectant (for example sodium hypochlorite) is bought in drums, transported and stored. This chain brings several problems: hazardous-goods transport and storage requirements, loss of efficacy over time, and continual supply dependency.

On-site generation removes this chain. The facility produces its own disinfectant, keeping only salt as an input alongside electricity. This makes a clear difference to both safety and operating cost.

Where is it used?

ECA technology is used today across a broad range — from drinking-water networks to swimming pools, food-processing plants to healthcare facilities, agricultural irrigation to livestock. The common thread is always the same: the need for safe, effective and continuous disinfection.

What actually governs efficacy: redox potential

The strength of an ECA solution is usually described with a single number — free chlorine concentration. Measurements show the picture is more complicated.

Kim, Hung and Brackett separated the variables behind electrolyzed oxidizing water’s efficacy: pH, oxidation–reduction potential (ORP) and residual chlorine. By comparing against chemically modified solutions engineered to share properties with EO water, they assessed each variable’s contribution to inactivation independently. ORP emerged as the governing variable.1

For an operator that means redox potential is not a derived indicator of free chlorine but a process parameter to be monitored in its own right. It is why the Aquamirus E.C.A. system measures and reports ORP independently.

Why pH matters this much

How much of the chlorine generated at the anode remains in the active hypochlorous acid form is set by the water’s pH. The dissociation constant describing that equilibrium was measured in 1948: pKa ≈ 7.5.3

The practical consequence: at pH 6 roughly 97% of free chlorine is in the active form; at pH 8 that falls to 26%, and at pH 9 to 3%. This is why cell design matters: in a diaphragm cell the hydroxide formed at the cathode stays out of the anolyte, so the anode-side solution remains in the range where hypochlorous acid dominates.

Measured effect on viruses

The efficacy of electrolyzed water is not limited to bacteria. Tamaki and colleagues tested neutral electrolyzed water against avian influenza viruses.

The finding: with the solution at 43 ppm free available chlorine or above, the titre of highly pathogenic H5N1 and low-pathogenic H9N2 fell by more than 5 log within 1 minute, irreversibly. At free chlorine below 17 ppm the effect was absent; the minimum threshold for a virucidal effect was estimated at about 40 ppm.4

A notable detail from the same study: no viral gene fragments could be amplified from virus inactivated by the neutral solution — the effect is structural disintegration, not a superficial loss of activity.

The method’s standing in industry

Industrial use of electrolyzed water has been reviewed in the peer-reviewed literature. A review focused on the food industry records that the method’s only chemical input is salt, that generation can take place at the point of use, and that it offers cost and environmental advantages over conventional systems.2