Advanced oxidation of tertiary wastewater micropollutants with nearly-zero contact time

Ozone is a powerful oxidant capable of degrading a wide range of contaminants, but its low mass transfer with conventional devices poses challenges for effective application in advanced oxidation processes and highly reactive matrices such as wastewater. This study evaluates the performance of MITO 3 X ® technology, a system designed to enhance ozone mass transfer and radical yields therefore optimizing the reactivity between pollutants and oxidative species with almost instantaneous contact time (<1 s). This research investigates MITO 3 X ® efficacy in degrading seven pollutants including Methylene blue (MB), 4-chlorobenzoic acid (pCBA), Caffeine (Caf), Acetaminophen (APAP), Ciprofloxacin (Cipro), Carbamazepine (CBZ), and Sulfamethoxazole (SMZ) as a function of water quality (high, medium, and low). Here, ‘high’ denotes dechlorinated, GAC-filtered water without added scavengers; ‘medium’ includes 5 mg. L⁻¹ nitrite (NaNO₂); and ‘low’ includes both 5 mg. L⁻¹ nitrite and 10 mg. L⁻¹ TOC (as methanol) thereby reflecting progressively stronger radical/ozone-scavenging matrices. Results indicate that ozonation efficiency, measured as (C₀-C)/C₀*100, reached up to 85 ± 5 % under high water quality, and approximately 65 % in medium quality, and 45 % in low quality, highlighting the impact of scavengers on advanced oxidation performance. A multivariate analysis examined the effects of MITO 3 X ® operational parameters, including impeller speed, water flow rate, and ozone capacity, on pollutant removal. The mass of ozone injected (e.g., controlled via adjustment of ozone capacity of the ozone generator) was dominant, with mixing and water quality also contributing through their interactions. The results defined operating conditions that maximize removal under nearly zero (e.g., < 1 s) contact time and highlighted the potential of MITO₃X® as a compact, efficient ozonation option for tertiary wastewater treatment and micropollutant control. • Enhanced ozone reaction efficiency driven by pressure and mixing. • Evaluated ozonation efficiency across three water matrices. • Design of experiment is a powerful tool for system optimization. • ANOVA revealed inter-dependency between mixing and water quality.