A review on ozonation and17a-ethinylestradiol - formation and effects in the environment of the by-products

Abstract: Today, waste water treatment plants do not remove pharmaceutical residues from the water (as there are currently no regulations for wastewater treatment in regards to pharmaceuticals residues in Sweden) resulting in a high concentration of pharmaceuticals reaching the environment. The Swedish environmental protection agency have recently concluded that there is a need for advanced treatment of pharmaceuticals in wastewater. One of the most promising techniques is ozonation however, the process can generate ecotoxic by-products. This study provides an overview of the current knowledge of by-products of 17α-ethinylestradiol (EE2), generated during the ozonation process. Special emphasis is on showing if by-products are produced in the ozonation process when removing EE2 and in what concentrations. Additionally, whether the by-products have an ecotoxicological effect on the environment and if there are any measured that can be taken to reduce the production of by-products. Method used to conduct this study was a systematic search over five databases and one search engine. This study shows that by-products of EE2 are generated during ozonation. However, the results shows that there is a huge gap in knowledge, in regards to the amount of by-products created and in what concentration also their ecotoxcity and possible risk to the environment are mostly unknown. Some by-products have estrogenic activity and have shown to have detrimental effect on fetal rats testosterone secretion. This study shows therefore possible post ozonation treatment steps that could be implemented to reduce the potential toxicity of by-products reaching the environment. The knowledges gap needs to be corrected with future studies, as ozonation is one of the most likely treatment techniques for pharmaceuticals to be implemented in the future.