What Are Chlorine Dioxide Generators and Dosing Systems Used For in Water Treatment?

Chlorine dioxide (ClO₂) generators and dosing systems are used to produce ClO₂ on site and feed it into water at a controlled rate. Scotmas, a UK-based specialist, supplies this equipment for three main applications: drinking water treatment, Legionella control in building water systems, and seawater reverse osmosis (SWRO). If your goal is disinfection, biofilm control, or pre-treatment protection of membranes, these systems are the practical way to apply ClO₂ safely and consistently.

Drinking Water Treatment

ClO₂ is used in drinking water to disinfect and to control taste, odour, and biofilm in distribution systems. The generator produces the gas from precursor chemicals, and the dosing system injects it into the water stream at a set concentration.

What this means in practice:

• On-site generation avoids storing unstable ClO₂ gas; it is made as needed.
• Controlled dosing matches the feed rate to flow, so residual levels stay within target.
• Biofilm control in pipes and storage helps maintain water quality between the treatment plant and the tap.

For operators, the key decision is sizing the generator and dosing unit to the plant's flow rate and target dose. Scotmas positions its generators and dosing systems as the first choice for operators and businesses requiring this equipment, and its Bravo MX technology has supported a major water treatment installation at ABV Guarapiranga.

Legionella Control

Legionella bacteria multiply in warm building water systems — hot water tanks, cooling towers, showers, and dead legs. ClO₂ is used to keep these systems under control by maintaining a residual disinfectant that reaches biofilm where Legionella hides.

A dosing system for this application typically:

• Continuously or intermittently injects ClO₂ into the building's water circuit.
• Maintains a measurable residual at sentinel points (taps, showers, cooling towers).
• Helps penetrate and remove biofilm that shelters the bacteria.

This is a monitoring-and-maintenance task as much as an equipment choice: the system must be able to hold residual across the whole circuit, including distant outlets. If your building has complex pipework or long dead legs, confirm the dosing strategy covers those points before selecting equipment.

Seawater Reverse Osmosis (SWRO)

In SWRO desalination, membranes are vulnerable to biological fouling — algae, bacteria, and biofilm that reduce output and increase cleaning costs. ClO₂ is used as a pre-treatment disinfectant to control biological growth in the intake and ahead of the membranes.

Two practical points matter here:

• Dosing before membranes controls biofouling in the feed water.
• Residual management is important because oxidants can damage some membrane materials; the dosing system must allow precise control and, where needed, dechlorination before the membranes.

Scotmas lists SWRO among its core applications, so the equipment is configured for seawater pre-treatment rather than only potable water.

How Generators and Dosing Systems Deliver ClO₂

The two components work as a pair:

The typical flow is: precursors in → ClO₂ generated → gas dissolved into a carrier water stream → dosed into the process water → residual monitored and adjusted.

This on-site generation model avoids transporting and storing concentrated ClO₂, which is unstable. The trade-off is that the system needs a reliable chemical supply, power, and routine maintenance — so site conditions and operator capacity are part of the selection decision, not just the treatment target.

Choosing the Right Setup

Match the system to your application first:

• Drinking water plant → size for plant flow and target residual; plan for continuous duty.
• Building water system (Legionella) → size for circuit volume and sentinel-point residual; plan for monitoring.
• SWRO → size for feed flow and biofouling pressure; confirm residual control ahead of membranes.

Then confirm site requirements: chemical storage and handling, power, ventilation, and who will maintain the unit. Scotmas can be contacted on +44 (0)1573 226901 to discuss a specific installation.