What Does Ozone Do in Water Treatment? Uses, Limits and Safety

Every ozone system has the same four blocks:

The scale logic: the generator is sized for the ozone demand of your water (measured, not guessed) plus the disinfection residual target, at your peak flow. Like every stage in this knowledge base, the sizing input is the water test — organic content and iron/manganese consume ozone before it reaches the microbiology, and that demand must be in the calculation.

Four duties where ozone outperforms alternatives:

1. Bottled and packaged water — a controlled ozone residual can disinfect water and help sanitize bottle and filling-line surfaces, then decays to oxygen without leaving a persistent taste. This makes ozone common in bottled-water plants, where hygienic control at filling is critical. The business context is in our water refilling station guide.
2. Taste, odor, and color — as an oxidant, ozone can break down many odor compounds, including geosmin and 2-methylisoborneol (MIB), that resist conventional filtration; see the sulfur-smell guide, where ozone is one oxidation option.
3. Iron and manganese oxidation — rapid oxidation ahead of filtration without adding a persistent disinfectant; the iron and manganese guide compares ozone with aeration and other oxidants.
4. Cooling towers and process water — biofilm control with lower chemical residuals in suitable waters.

The two technologies answer different questions. Our UV vs ozone water-treatment guide provides the full side-by-side comparison:

The pattern that falls out: UV for the final barrier on potable systems; ozone where oxidizing power or a line residual is required. Many plants run both — ozone upstream for oxidation and line protection, UV as the final barrier — including in food and beverage plants.

When the source water contains bromide, ozone converts some of it to bromate — a regulated drinking-water contaminant (WHO and major national standards set a low microgram-per-liter limit; verify the current figure for your jurisdiction during design). This is not a reason to avoid ozone; it is a reason to test bromide and state the control strategy on the quotation:

• Bromide level from the water analysis
• Ozone dose and residual strategy (lower dose/contact combinations reduce bromate formation)
• Alternative approaches where bromide is high and limits are strict (membrane removal of bromide, or non-ozone disinfection for that stream)

A supplier who does not mention bromide on a bromide-containing water has not finished the engineering. Verify the applicable limit and control references at design time — the numbers belong to your regulator, not to a supplier's brochure.

The system-level specification checklist covers what the complete stage must do:

1. Application and target: disinfection (which organisms/standard), oxidation (which metals/compounds), or bottled-water residual — the duty changes the CT design
2. Water analysis including bromide, organics proxies, iron/manganese (they consume ozone first)
3. Contact and residual design: contact time, target residual, quench/off-gas destruct
4. Materials: ozone is aggressive — compatible piping, tanks, and seals throughout the skid
5. Safety: ambient ozone monitoring for plant rooms, interlocks, destruct on vents
6. Verification: commissioning test of residual at design flow, and the monitoring regime

Generator-level requirements — output basis at a stated concentration, feed gas, cooling, turndown, and the priced service schedule — are itemized separately. Generator selection — output classes, feed-gas choice, and cost trade-offs — has its own guide: ozone generators for water treatment.

KONCHE has manufactured commercial water-treatment systems since 1997, with packaged plant capacities from 0.25 to 50 m³/h. In an ozone project, the relevant supply scope is the complete stage — generation, gas preparation, injection, contact, monitoring, and off-gas control — rather than the generator alone.