Intensification strategies for cytostatics degradation by ozone-based processes in aqueous phase

Over the past decade there has been an increasing concern on the presence of cytostatics (also known as anticancer drugs) in natural waterbodies. The conventional wastewater treatments seem not to be effective enough to remove them, and therefore new processes must be considered. This work investigates the performance of ozonation (O3), catalytic ozonation (O3/Fe2+) and peroxone (O3/H2O2) processes, under dark or UV radiation conditions, for the degradation of cytostatics of worldwide concern. The degradation of bicalutamide (a representative of recalcitrant cytostatics) was firstly assessed in batch and then in a tubular column reactor (continuous flow mode runs) using a wastewater treatment plant (WWTP) secondary effluent. Bicalutamide removal ranged between 66 % (O3) and 98 % (O3/H2O2/UV) in continuous flow mode runs, the peroxone process being the most effective. The performance of these processes was then assessed against a mixture of twelve cytostatics of worldwide concern spiked in the WWTP effluent (25–350 ng/L). After treatment, seven cytostatics were completely removed, whereas the five most recalcitrant ones were eliminated to an extent of 8–92 % in O3/H2O2, and 44–95 % in O3/H2O2/UV. Phytotoxicity tests revealed a noticeable reduction in the effluent toxicity, demonstrating the feasibility of these processes in realistic conditions as tertiary treatment. [Display omitted] •Different approaches are tested to increase the elimination of cytostatics with O3.•The peroxone process (O3/H2O2) yields higher bicalutamide removal than O3 and O3/Fe2+.•Runs with WWTP effluent reveal a higher efficiency for O3/H2O2 and O3/H2O2/UV.•The selected processes eliminated 44–100 % of cytostatics in realistic conditions.