Removal of anti-cancer drugs from real wastewater effluent by photocatalytic membrane reactor (PMR)

The presence of anti-cancer drugs, used for chemotherapeutic treatments, in surface waters raises some environmental concerns given their mutagenic and genotoxic effects. For this reason, new treatments are currently being studied for the degradation of these drugs. The aim of this study was to investigate the performances of a photocatalytic membrane reactor for the removal of three anti-cancer drugs – 5-fluorouracil, capecitabine, cyclophosphamide - from real wastewater effluent. Therefore, photocatalytic degradation experiments were performed in laboratory grade water and in secondary wastewater effluent at a TiO2 concentration of 1.5g/L identified as the optimum for the production of active radicals. A reduction of degradation rates by more than 75% was observed for all three anti-cancer drugs in secondary wastewater effluent compared to pure water. Degradation experiments in secondary wastewater effluent filtered by reverse osmosis allowed to identify four water species responsible for the reduced degradation rates: bicarbonate, chloride, sulphate and calcium ions. Finally, an economic evaluation of this process suggested that the addition of a fine membrane like reverse osmosis as pre- or post-treatment could reduce the total cost of photocatalytic membrane reactor but further investigations are required. Overall, the results obtained in this work evidenced the need to acquire a better understanding of the mechanisms that deactivate photocatalysis in real water matrix in order to develop a more economically attractive photocatalytic membrane reactor that can efficiently degrade anti-cancer drugs in real conditions.