Decomposition of contaminants of emerging concern in advanced oxidation processes

This paper compares the removal degrees of selected contaminants of emerging concern in water solutions during advanced oxidation processes (AOPs), such as H₂O₂, O₃, UV, UV/TiO₂, UV/H₂O₂, and UV/O₃. The tested micropollutants belong to the following groups: pharmaceuticals, dyes, UV filters, hormones, pesticides, and food additives. The highest removal rate of pharmaceutical compounds was observed during the UV/TiO₂ process. The decomposition of hormones in this process exceeded 96% and the concentration of the UV filter dioxybenzone was reduced by 75%. The pesticide triallat and the food additive butylated hydroxytoluene were most effectively oxidized by the UV process and their removal degrees exceeded 90%. The lowest removal degree in all examined processes was observed in the case of caffeine. Toxicological analysis conducted in post-processed water samples indicated the generation of several oxidation by-products with a high toxic potential. The presence of those compounds was confirmed by the GC-MS analysis. The performance of the UV/O₃ process leads to the increase of the toxicity of post-processed water solutions, especially solutions containing degradation by-products of carbamazepine, diclofenac sodium salt, acridine, trialatte, triclosan, and β-estradiol were characterized by high toxicity.