Immediate Ozone Reaction During Micropollutant Removal at Advanced Wastewater Treatment Using Ozone-Strong Water

The EU’s 2024 Urban Wastewater Directive (UWWD) sets strict requirements for the elimination of micropollutants (MPs), creating the need for efficient, advanced treatment technologies. This study investigates the performance of the ozone strong water (OSW) system, a novel on-demand ozone injection technology, focusing on its ozone consumption dynamics in advanced wastewater treatment. OSW integrates high-efficiency mixing and immediate ozone consumption, minimizing bromate formation and operating costs. Full-scale experiments demonstrated that ozone was consumed within 2 s after injection. The immediate ozone reaction alone accounted for 63–86% of total MP removal, with 80% elimination achieved at a specific ozone dose of 0.3 go3/gDOC (dissolved organic carbon). When combined with upstream biological treatment, as outlined in the UWWD, an average MP elimination of 90% was achieved with only 0.24 go3/gDOC. This indicates that lower ozone doses may be sufficient to achieve the regulatory target of 80% MP removal. However, suspended solids and detached sludge interfered with the immediate reaction and resulted in 0.1–0.2 go3/gDOC higher ozone doses to maintain comparable eliminations. These findings emphasize the importance of effective pretreatment and final clarification to ensure consistent performance and compliance with regulatory targets.