Technical note

Can Electrochemical Treatment Replace Biocide?

Suppression is not sterilisation. Confirm the boundary by system type, temperature and Legionella rules, and keep a verifiable biocide measure.

“With the electrochemical unit installed, can I stop the biocide?” You can reduce it — but whether to stop entirely depends on system type, water temperature and Legionella risk. Stating the limits is more responsible than a flat “yes”.

1. Electrochemistry suppresses micro-organisms; it does not sterilise

Oxidants generated at the anode (mainly free chlorine) suppress planktonic bacteria and damage part of the biofilm; the alkaline environment and calcium/magnesium deposition at the cathode also change attachment conditions. But chlorine output is limited by current and water chemistry, far below the concentration of a shock biocide dose. It is suited to routine suppression, not to replacing periodic shock treatment.

2. Three preconditions to confirm first

First, system type: open cooling towers and closed loops tolerate oxidants differently. Second, temperature and process: systems running hot with high organic load (food, pharmaceutical) carry higher biofilm risk and cannot rely on low-level free chlorine alone. Third, regulations and hygiene requirements: for hospitals, hotels and large public buildings, Legionella control is explicitly regulated, so verifiable biocide measures and test records must be retained.

3. The safer pattern: electrochemical as the base, verifiable biocide retained

Use electrochemical treatment for continuous suppression and keep shock biocide dosing as a periodic measure, deciding whether to dose from three data sets: heterotrophic plate count, biofilm coupons and free chlorine. Total chemical consumption falls without losing emergency capability. If a site truly wants to stop chemicals entirely, run a comparison period first: HPC, slime volume, exchanger temperature difference and corrosion rate must all stay stable before it can be confirmed.

4. More free chlorine is not better

Free chlorine attacks carbon steel and copper, and copper systems need tighter limits. Operating parameters of the electrochemical unit — current, duty cycle, polarity-reversal interval — should be derived backwards from the free chlorine target, not run at full power. This is why we recommend on-line free chlorine and pH monitoring interlocked with the equipment.

5. In short

Electrochemical treatment can substantially cut biocide consumption and usually provides routine suppression in industrial circulating water. But “stop all biocide” must be assessed per system type and regulation, with monitoring evidence retained. Keeping these three things separate prevents a “zero chemical” slogan from becoming a costly mistake.