Performance comparison of microalgae-based and activated sludge with membrane filtration (AS-MBR) for emerging contaminant removal and wastewater reuse

Abstract

The removal efficiency of microalgae cultures was compared to that of an activated sludge system with ultrafiltration. Three systems were assessed: an outdoor algae pond, a lab-scale setup simulating open-air conditions, and a full-scale activated sludge facility. High removal rates (>80 %) were observed for hydrophobic, biodegradable or volatile compounds across all systems, despite differences in treatment nature. In microalgae systems, bioadsorption and photodegradation were key pathways, with enhanced removal of UV-sensitive compounds in the outdoor pond. In the activated sludge membrane-assisted system, biosorption and volatilization led to very low pollutant concentrations in the effluent. The membrane bioreactor outperformed conventional activated sludge systems due to higher aeration, sludge age and the elevated solids concentration. The three tested systems produce final effluents that met European standards for reclaimed water, in terms of biological contamination, and the limits proposed for emerging contaminant removal.