Water Disinfection by salt electrolysis OSG HydrexⓇ

An effective alternative technology to chemical biocide treatment for your cooling systems.
Equipment for disinfection of cooling towers

Environmental regulations push industrial companies to review their chemical water treatment, the choice of the active substances to use and their strategies for cooling towers cleaning service and sanitization.

Based on salt electrolysis, OSG Hydrex generates a freshly produced disinfection solution in situ when and where it is needed. It offers a greener alternative to conventional oxidizing biocides with reduced handling of chemicals. 


Effective cooling systems disinfection with a smaller environmental footprint

For any industrial site, the oxidizing treatment of water in the cooling systems is essential for Health and Safety and asset protection  . But while regulations increasingly push to restrict   the use of synthetic biocides,  sodium hypochlorite (bleach) and bromine to limit environmental impact, they also impose control of the  bacterial growth and the legionella risk. 

Using only salt, soft water and electricity, OSG Hydrex (for On Site Generator) generates in situ when needed an  oxidizer disinfectant substituting to bleach and bromine products. Because the solution is freshly produced, it does not degrade over time. 

Part of Veolia’s comprehensive treatment programs for cooling systems, OSG Hydrex offers a more environmentally alternative to conventional oxidizing biocides and significantly reduce the use of non oxidizing biocides. 

OSG Hydrex is simple to implement and proposed in a full rental package for continuous performance and flexibility: 

  • Equipment including online analyzers, injection and storage devices.
  • Hydrex chemicals.
  • Comprehensive service (analytics, maintenance, support).

Available in eight models ranging from 1.44 to 60 kg/day of Free Available Chlorine (FAC) , OSG HydrexⓇ is applicable in most industrial sectors for:

  • Cooling towers. 
  • Pretreatment of raw water, drinking water. 
salt electrolysis OSG Hydrex

Features and benefits

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Reduced storage and handling of hazardous substances 

Improved Health & Safety

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Reduction of chlorination by-products 

  • Higher COC
  • Better blowdown quality

Savings on 

  • Chemicals
  • Transport, packaging costs
  • CAPEX (Hydrex rental package)
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Full compliance with regulatory standards.


Improved environmental impact (carbon / water footprint / discharge quality)

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Efficiency at free pH 

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More efficient than conventional oxidizing biocides on biofilm


Case study

Our customer is a liquefied gas production plant in France that delivers high-purity oxygen for the laser market, nitrogen-compliant with food additive regulations and argon perfectly suited to the welding markets.

The site’s cooling towers are equipped with a 225 m3 tank delivering a cooling capacity of 12,500 kW.

The customer was looking for clean and secure operation of its cooling towers with optimized yield and production availability. They must comply with stringent regulations requiring all manufacturers to have very precise control over the injection of biocides to limit the amount of pollutants in their discharge.

Veolia Water Technologies proposed an Hydrex  treatment program including the OSG HydrexⓇ an equipment which produces a oxidizing solution for the onsite disinfection of the cooling towers. 

On-site support for cooling water disinfection

Based on salt electrolysis, the On Site Generator (OSG) HYDREX offers a genuine and ecological alternative to the use of organic biocides (Sodium hypochloride, Bromine), which is increasingly restricted. 


Results for this customer

❏ No fouling identified
❏ No apparent corrosion
❏ Remarkable efficiency on cooling tower surface condition

❏ Reduction of mineral deposits by dispersant effect
❏ Elimination of biofilm-type microbial deposits

❏ Improved clarity of cooling tower circuit water
❏ No biomass creation in the circuits
❏ No Legionella detected (cultivation according to AFNOR NFT90-431)

Diagram of the OSG technology  

Fonctionnement Hydrex Disinfection by salt electrolysis