Disinfection and oxidation technology selection has long-term consequences for compliance, operating requirement, and residual management. This guide compares the principal options across key engineering criteria.
Generated on-site by corona discharge, ozone is dissolved into the water and oxidises micropollutants, disinfects pathogens (CT ~0.5–2 mg·min/L for Giardia), and removes colour. Reactive towards unsaturated organic bonds. Half-life in water 10–30 minutes. Must be catalytically destroyed in off-gas. Bromate formation risk when bromide >50 µg/L. See our ozone generators and ozonation systems.
Low-pressure (254 nm) or medium-pressure UV lamps deliver photons that directly damage microbial DNA, preventing replication. CT values: 40 mJ/cm² for 4-log Cryptosporidium; 40 mJ/cm² for 4-log Giardia. No chemical residual generated. No disinfection by-product (DBP) formation. Does not oxidise dissolved organic compounds. See our UV disinfection systems and UV equipment.
Generate hydroxyl radicals (·OH, E° = 2.80 V) — the most powerful oxidant available in water treatment — by combining UV + H&sub2;O&sub2;, O&sub3; + H&sub2;O&sub2;, Fenton reagent, or photo-Fenton. Non-selective: destroys virtually all organic micropollutants including pharmaceuticals, PFAS precursors, and refractory industrial chemicals. See our AOP overview, UV/H&sub2;O&sub2;, Fenton, and photo-Fenton pages.
Ozone provides disinfection plus colour and odour removal. UV is chemical-free and effective against chlorine-resistant pathogens. AOP destroys micropollutants and pharmaceutical residues. We select based on your target contaminants, water matrix, and downstream use.
| Parameter | Ozone | UV | AOP (UV/H&sub2;O&sub2;) |
|---|---|---|---|
| Primary mechanism | Direct oxidation (O&sub3; + ·OH) | DNA photodamage | Hydroxyl radical (·OH) |
| Disinfection efficacy | Excellent (4–6 log) | Excellent (4–6 log) | Excellent |
| Cryptosporidium / Giardia | Effective (CT 0.5–2) | Most effective (40 mJ/cm²) | Effective |
| Virus inactivation | Excellent | Excellent (low CT) | Excellent |
Low-pressure UV is the lowest-cost, DBP-free disinfection option for clear treated water (UVT >85%). Standard for municipal water treatment final disinfection and industrial water reuse where UVT is adequate.
Ozone at 0.5–1.0 mg O&sub3;/mg DOC destroys endocrine disruptors, pharmaceuticals, and pesticides. Widely deployed in EU drinking water plants to meet the EU Drinking Water Directive recast (2021/2115). Often combined with BAC filtration.
When biological treatment fails to achieve consent limits due to refractory compounds (azo dyes, pharmaceuticals, industrial solvents), UV/H&sub2;O&sub2; or Fenton AOP is the engineering solution. See example applications.
UV is the preferred tertiary disinfection step for treated municipal effluent reused for irrigation, toilet flushing, or industrial cooling, due to absence of DBPs and chemical storage requirements.
Ozone combined with UV provides taste/odour control and disinfection in aquatic facilities. In aquaculture recirculating systems, ozone-UV controls pathogens while avoiding chlorine toxicity to fish.
Persistent azo dyes and tannin colour that resist biological treatment are destroyed by Fenton or photo-Fenton AOP to levels that meet discharge consent. See textile colour removal.
On-site ozone generation, dissolution, and contact systems for water and wastewater.
View OzonationLow and medium-pressure UV systems, dose calculators, and validation protocols.
View UV SystemsUV/H&sub2;O&sub2;, Fenton, photo-Fenton, and ozone/H&sub2;O&sub2; AOP systems.
View AOPCalculate UV dose, lamp power, and reactor volume for your application and flow.
Use CalculatorOur process engineers will evaluate your application and recommend the optimal solution for your flowrate, quality targets, and budget.
Our expertise spans multiple industries with sector-specific water treatment solutions.