Comparison of ozonation removal for PPCPs in secondary treated sewage by microbubble generator and ejector

This study analyzed residues of PPCPs in secondary treated sewage water, and their amount eliminated by ozonation processes. A microbubble nozzle and ejector were used to dissolve ozone. To consider a low concentration of PPCPs, a SPE method was performed on samples prior to the analysis. The concentration of dissolved ozone was 4.00 mg/L in the microbubble and 2.49 mg/L in the ejector. To examine elimination trends, the experiment was also performed at a low concentration of ozone, 1/10 of its original concentration. The maximum elimination rate on average was 93.0% in the ejector, higher than that in the microbubble (90.1%), but 16 PPCPs were found to show a relatively high elimination rate in the microbubble, higher than the ejector. Elimination trends with respect to time were distinguished based on inflection point, and 11 PPCPs were concentrated on the latter half of the microbubble after the inflection point at the low concentration of ozone, which was compared to other cases. In the source water, concentrations of 2 PPCPs were higher than the reference toxic concentration based on the QSAR model, but after treatment, only bezafibrate was over the value when the ejector with low ozone injection concentration was applied.