How does electrochemical activation (ECA) work?
Electrochemical activation (ECA) is the process of passing a dilute brine solution through an electrolysis cell to convert it into a disinfectant solution dominated by hypochlorous acid. The only inputs are salt, water and electricity; the result is fresh disinfectant produced where it is needed, with no hazardous chemical transport or storage.
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.
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. The solution produced is a balanced disinfectant of near-neutral pH, dominated by hypochlorous acid. This is the most common type for water and surface disinfection.
- Diaphragm (membrane): The anode and cathode are separated by a membrane, producing two solutions: a strong oxidant (anolyte) and an alkaline reductant (catholyte). Used in special applications.
For most water and surface disinfection applications, the arrangement that produces a neutral-pH hypochlorous acid solution is preferred, because it offers both the most effective form of chlorine and an equipment-friendly pH at once.
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 our systems measure and report 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%. Undivided cells operating close to neutral pH are not a coincidence — they are a direct consequence of that curve.
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