Enhanced degradation of benzo[a]pyrene and toxicity reduction by microbubble ozonation

The microbubble technique has drawn great attention for efficient utilization of ozone for advance oxidation processes. Therefore, in this study, microbubble ozonation was investigated to evaluate the removal efficiency and toxicity reduction of benzo[a]pyrene. Compared with conventional macrobubble ozonation, microbubble ozonation produced higher concentrations of hydroxyl radicals and ozone in aqueous solutions, resulting in more efficient and persistent degradation of benzo[a]pyrene. Moreover, microbubble ozonation completely removed the acute toxicity of benzo[a]pyrene to Daphnia magna, whereas the toxicity reduction by macrobubble ozonation was not consistent owing possibly to toxic degradation products. These findings suggest that microbubble ozonation is a promising technique in terms of both chemical degradation and toxicity reduction of organic pollutants.