BACKGROUND: The persistence of microcontaminants through conventional wastewater treatments is a matter of concern and it suggests the implementation of advanced treatment steps. Although there is evidence that reverse osmosis (RO) is the most efficient treatment for the the removal of these compounds, it has the drawback of producing significant amounts of highly polluted brine. In this work, chemical analyses and toxicity bioassays were combined to evaluate the removal of different pharmaceuticals and of dioxin-like compounds from RO brine through oxidative processes such as ozone, UV and UV/H2O2. RESULTS: The removal of the selected pharmaceuticals required a relatively high oxidative capacity, either by ozonation or by the combination of UV radiation and H2O2. Bioassays showed a significant dioxin-like activity in brine samples, whereas antibacterial or estrogenic activities were negligible. UV by itself was the least efficient in removing this dioxin-like activity. Ozonation appeared as the most competent treatment. CONCLUSIONS: The results of this work indicate the usefulness of advanced oxidation methods, especially ozonation, to remove biologically active micropollutants from brine samples. They also show that only the combination of chemical analyses and bioassays allows complete characterization of the efficiency of advanced water treatment processes to remove recalcitrant pollutants. (C) 2014 Society of Chemical Industry