Targeting recalcitrant organic pollutants—such as pharmaceuticals, pesticides, and industrial solvents—the Ozone-Based Advanced Oxidation Process (AOP) leverages hydroxyl radicals (•OH, oxidation potential 2.8 V) to mineralize non-biodegradable compounds into CO₂ and H₂O. Ozone (O₃), generated via corona discharge (air/oxygen feed), is either used alone or combined with UV light (UV/O₃) or hydrogen peroxide (O₃/H₂O₂) to enhance radical production.
Mechanism & Components
- Ozone Generation: High-voltage electrodes split O₂ molecules into O atoms, which react with O₂ to form O₃ (yield: 10–15% by weight).
- Contactor Reactor: Bubble columns or spiral reactors maximize gas-liquid contact, with residence times of 10–30 minutes.
- Destructor: Unreacted ozone is decomposed into O₂ to meet safety standards.
Performance & Use Cases
- Rapid Degradation: Oxidizes 90% of micropollutants (e.g., bisphenol A, sulfamethoxazole) within 15–60 minutes, critical for wastewater reuse in semiconductors and healthcare.
- Zero Residues: Ozone decomposes completely, avoiding secondary pollution unlike chlorine-based methods.
- Synergistic Effects: UV/O₃ systems achieve 50% higher radical yields, reducing ozone demand by 30% in treating landfill leachate (removing ammonia and recalcitrant organics).
Challenges
- Cost Intensity: High capital (USD 1,500–2,500/m³) and operational costs (electricity 1–2 kWh/kg O₃, corrosion-resistant materials like 316L stainless steel).
- pH Sensitivity: Optimal performance at pH 7–9; acidic conditions (pH < 6) reduce radical formation.
- Safety Risks: Requires explosion-proof environments and ozone leak detection systems due to its high reactivity.
