Removal of Organic Micropollutants from Wastewater in Biofilm Systems

Abstract: The presence of organic hazardous substances in the aquatic environment, such as pharmaceutically active compounds and personal care products, has become a worldwide issue of increasing environmental concern. Present at concentration of nano- to milligram per liter, they are defined as organic micropollutants (OMPs).  Wastewater treatment plants (WWTPs) have been recognized as the main route of emission of OMPs into the environment and as hotspot for antibiotic resistance. Not being designed for the elimination of micropollutants, the removal is often incomplete, resulting in continuous discharge. Therefore, research currently focuses on the enhancement of conventional WWTPs via physical-chemical and biological treatment processes. Among biological processes, biofilm-based treatment technologies have been found more efficient in the biotransformation of OMPs than conventional activated sludge treatment processes. Aerobic granular sludge (AGS) is a form of free-floating biofilm technique for simultaneous removal of organic carbon, nitrogen, and phosphorus in a single process step. The longer solid retention time, the higher concentration and microbial diversity and the presence of micro-niches of different redox conditions are features of AGS that make this system very attractive for the removal of OMPs. An in-depth understanding of the fate of OMPs in such systems under different operational conditions is still required. The present work investigates the degradation mechanisms of OMPs in biomass from both full-scale treatment plants and laboratory reactors. Specifically, it focuses on the impact of different conformations of AGS on the sorption of selected pharmaceuticals and the potential of different biofilm systems at the full scale WWTP to eliminate OMPs.