Removal of emerging organic micropollutants from real hospital wastewater by modified ultrafiltration membranes

Membrane biofouling, characterized by the adherence and growth of microorganisms on the surface of a membrane, poses a significant challenge to the effectiveness of membrane bioreactor (MBR) technology. Enhancing anti-biofouling characteristics, particularly the prevention of bacterial adhesion to the membrane, is crucial for the sustained operation of MBR over the long term. One of the most popular methods for enhancing these characteristics is surface modification. In this study, two distinct concentrations of 150 µM and 300 µM of BisBAL −a chelate derived from bismuth with strong antibacterial action on a variety of microorganisms- were added to polymeric membrane solutions. Using these solutions, flat sheet (FS) and hollow fiber (HF) membranes were produced via the phase inversion method to examine their removal capabilities for micropollutants in a real hospital wastewater. Caffeine (CAF), Paracetamol (APAP) and Ciprofloxacin (CPFX) were observed as target micropollutants during a pilot-scale MBR operation. The chemical modification of the membranes enhanced the characteristics of the membrane material. Pure water flux values increased while contact angles were decreased in modified membranes When compared to bare membranes, BisBAL-added modified membranes were observed to reject CAF, APAP and CPFX more effectively. When 150 and 300 µM BisBAL is added to FS and HF membranes, the rejection efficiencies of CAF and APAP reached their maximums, exceeding 80 %. Remarkably, CPFX rejection in the case of FS membranes added with 300 µM reached about 30 %, whereas it surpasses 80 % in the case of HF membranes added with the same concentration. The mechanism behind the rejection of micropollutants by the membranes was determined to be adsorption. In addition to their enhanced resistance to biofouling, the new potential of these modified membranes was also demonstrated. The results suggested that membranes modified with 300 µM BisBAL were particularly optimal for the pilot-scale MBR operations in the future, with HF membranes generally outperforming FS membranes.