Removal of pharmaceuticals in water by introduction of ozonated microbubbles

Abstract

Ozonated-microbubble (O3-MB) was applied to remove 39 pharmaceuticals in 10 therapeutic classes (ant-ivirals, anti-bacterials, anti-cancer drugs, psychotropics, anti-hypertensives, analgesic-antipyretics, contrast media, bronchodilators, anti-pruritics, and herbal medicines) in water and the results were compared with those given by O3 alone and combined treatments with UV, and/or H2O2, or both. The summarized results clearly indicate that O3-MB based treatments significantly (P < 0.01) enhanced removal rates by 8–34% to O3 alone, and removal rates of >90% (>80%) were attained for 33 (37) compounds. Introduction of MB technology was indispensable to improve degradation of famciclovir (anti-viral), bicalutamide (anti-cancer), sulpiride (phychotropic) and acetaminophen glucuronide (analgesic-antipyretic) over 96.0%. Recalcitrant properties of all contrast media type compounds (iohexol, ioversol, iopromide, iomeprol and iopamidol) against both O3 and O3-MB were significantly improved by combined treatment with UV, and removal rates became 93.8–98.8% from 0% to 52.0%, indicating effectiveness of combined use of photolysis more than oxidation by hydroxyl radicals. Combination of UV and/or H2O2 with O3-MB increased the reaction rate constant by 2.9–5.5 times in average relative to O3 and O3-MB. In addition, MB treatment improved O3 consumption up to 2.8 times higher than the O3 treatments. These results indicate that the combined treatments of O3-MB with UV and/or H2O2 could minimize the environmental pollutant load of pharmaceuticals discharged into rivers. To the best of our knowledge, this is the first investigation which showed enhancement of removal rates of multiple pharmaceuticals together with combined use of UV and/or H2O2.