Application of a submerged photocatalytic membrane reactor with ultrafiltration membrane for ketoprofen removal during long term process: Impact of feed matrix

The research was focused on the evaluation of a long-term performance of a submerged photocatalytic membrane reactor utilizing ultrafiltration (SPMR-UF) operated in a continuous mode for removal of ketoprofen from various synthetic aqueous feeds (brackish, surface, seawater and secondary effluent of a wastewater treatment plant). The highest initial rate of ketoprofen degradation was found for brackish water. Nonetheless, after 24 h of the SPMR-UF operation the removal rate of the drug was similar for all feed types (93-96 %). The selected process parameters (suction pressure of -0.01 MPa and backflush frequency of 1 min: 30 min) allowed to realize the process without any permeate flux decline when brackish and seawater were applied. However, fouling was observed in the case of surface water and secondary effluent, mainly due to the presence of humic acids or peptone and meat extract in the feed. Autopsy of the membrane revealed CaSO4 and CaCO3 crystals on the TiO2 layer covering the membrane surface after treatment of brackish water, seawater and secondary effluent, indicating the important role of the photocatalyst in UF membrane scaling. It was concluded that since the main process determining the efficiency of SPMR-UF is photocatalysis, its optimization is of high importance.