Toxicity and degradation pathways of selected micropollutants in water solutions during the O₃ and O₃/H₂O₂ process

Ozonation is one of the most effective methods of water disinfection. This process, as a single method or with the involvement of other oxidizing agents, can be also used as an advanced decomposition process for hardly or non-biodegradable compounds. Ozone-based processes do not always lead to a complete mineralization of compounds. The oxidation of parent compounds may contribute to the formation of a significant number of new micropollutants with a high toxic potential. The paper presents the removal degrees of diclofenac sodium salt (DCF) and bisphenol A after the O₃ and O₃/H₂O₂ process. The processes were carried out at various times, that is, 10, 20, 30 and 60 min. The O₃ dose was 3 mg/L and the H₂O₂ dose was equal to 9 mg/L. The GC-MS analysis indicated the formation of different decomposition by-products during both oxidation processes. The type and concentration of generated new micropollutants depends on the pH of the water solution and the process time. It has been observed that the decomposition degree of DCF decreased with the increase in the pH of the reaction medium. An inverse relationship was observed for bisphenol A, where the largest number of oxidation by-products was observed in water solution at pH 11. The conducted toxicological analysis confirmed the toxic nature of the generated decomposition products.