Pharmaceutical Transformation Products Formed by Ozonation-Does Degradation Occur?

The efficiency of an advanced oxidation process (AOP) using direct and indirect ozonation for the removal of pharmaceutical residues from deliberately spiked deionized water was examined. Both direct and indirect ozonation demonstrated 34% to 100% removal of the parent compounds. However, based on the products' chemical structure and toxicity, we suggest that despite using accepted and affordable ozone and radical concentrations, the six parent compounds were not fully degraded, but merely transformed into 25 new intermediate products. The transformation products (TPs) differed slightly in structure but were mostly similar to their parent compounds in their persistence, stability and toxicity; a few of the TPs were found to be even more toxic than their parent compounds. Therefore, an additional treatment is required to improve and upgrade the traditional AOP toward degradation and removal of both parent compounds and their TPs for safer release into the environment.

Automated summary

The efficiency of direct and indirect ozonation in an advanced oxidation process (AOP) was evaluated for the removal of pharmaceutical residues in intentionally spiked deionized water. Both direct and indirect ozonation achieved removal rates ranging from 34% to 100% for the parent compounds. However, the study suggests that despite using accepted and affordable concentrations of ozone and radicals, the parent compounds were not fully degraded but transformed into 25 new intermediate products. These transformation products (TPs) were structurally similar to the parent compounds and exhibited similar persistence, stability, and toxicity. Some TPs were even more toxic than their parent compounds. Therefore, additional treatment is necessary to enhance the AOP for the degradation and removal of both parent compounds and their TPs to ensure safer release into the environment.