Pilot-scale study of ozonation, ozone-hydrogen peroxide, and UV-hydrogen peroxide for micropollutant removal from tertiary treated sewage effluent in Qatar

Treated sewage effluent (TSE) is a critical non-potable water source in arid regions such as Qatar, yet residual micropollutants pose environmental and health risks. Advanced oxidation processes (AOPs) offer promising solutions, but their performance in local wastewater matrices remains underexplored. A pilot-scale study evaluated ozonation (O-3), ozone-hydrogen peroxide (O-3-H2O2), and UV-hydrogen peroxide (UV-H2O2) for micropollutant removal from ultrafiltration-treated TSE. Influent and effluent were analysed for 243 pesticides and 56 pharmaceuticals. Removal efficiency, electrical energy per order (EEO), and cost were assessed. Nine pesticides and fifteen pharmaceuticals were detected, including fipronil (0.413 mu g/L), thiamethoxam (0.292 mu g/L), iohexol (4.06 mu g/L), and iopamidol (3.17 mu g/L). Ozonation at 3-4 mg/L achieved 80-90 % removal for most pesticides; acetamiprid remained resistant (similar to 50 %). Nearly all pharmaceuticals were reduced below reporting limits except iodinated contrast media, which UV-H2O2 removed most effectively (approximate to 79-86 %). O-3-H2O2 improved the degradation of ozone-resistant compounds. EEO was <0.3 kWh m(-3) for ozone-based AOPs for most of the compounds. A cost assessment at 200,000 m(3)/d showed unit costs of $0.019/m(3) (O-3), $0.023/m(3) (O-3-H2O2), and $0.124/m(3) (UV-H2O2), confirming the economic advantage of ozone-based options at scale. Ozonation (dose of 1.0 mg O-3/mg DOC) is recommended as the baseline AOP, followed by biologically active or granular activated carbon to address residuals and transformation products.