Alarming data have been pointing to a fact that natural waters were facing threats due to disperse pollution with persistent organic microcontaminants. Gradually, a scientific response introduced new integral approaches of water treatment based on advanced oxidation processes. Along with this arose a tendence to also understand their fate, transformations, and long-term effects when they already occur in the environment. The study is focused on a representative family of ubiquitous and genotoxic pollutants: phenolic compounds − constituents of industrial wastewaters, namely, phenol, 2,4-dichlorophenol and pentachlorophenol. Despite being common model pollutants in environmental research, wholesome multidisciplinary studies, investigating a variety of removal technologies at once, using modern instrumental analysis along with ecotoxicological assessments are rare, but essential. As so, the motivation was to fully understand complex degradation processes of named model phenolics in different matrices from chemical and ecotoxicological point of view. A focus was placed on profound analyses of treated fractions. This allowed a comparison of four approaches for chemical degradation: ozonation, photocatalytic oxidation with immobilised nitrogen-doped TiO2 thin films, their sequence, and anodic electrooxidations, thus, covering a wide range of three advanced technologies. Additionally, their environmental behaviour was tried to be understood. Therefore, natural conditions were simulated in incubated test mixtures to investigate a role of abiotic factors alone on natural transformations. We studied influence of sunlight, pH, sediments, humic substances, copper(II) ions, and oxygen. In order to collect data on target degradation progress, dechlorination, mineralization, changes in pH, chemical transformations, and evolution of selected by-products, numerous analytical methods and procedures were applied. Such as: HPLC-DAD, pH measurements, TOC analysis, UV spectroscopy, solid-phase microextractions (SPME) or liquid-liquid extractions (LLE) followed by GC-MS or GC-MS/MS, UHPLC-MS, ion chromatography, and ecotoxicological inhibition tests on Daphnia magna water flea organisms. Concluding results point to a fact that ozonation provides by far the most suitable pattern of degradation processes. In contrast, photocatalysis was found to be slow, marked by the accumulation of aromatic products. Preozonation is shown to reinforce the processes. As far as electrooxidations are concerned, data suggest that using BDD anode rather than MMO for degradation of phenol is to be preferred. But compromises about supporting electrolyte choice (NaCl, Na2SO4, H2SO4) need to be accepted, in order to provide suitable degradation pattern and less problematic transformation products. And lastly, it should be highlighted that chosen phenols are photolabile, yet their degradation is slow, but photoinduced transformations are complex when exposed to visible light and are considerably affected by their structure, pH and the presence of abiotic active agents.
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