CultiCultivating aerobic granular sludge in a lab-scale sequencing batch reactor - Removal of pharmaceutically active compounds, total phosphorus, total nitrogen and organic matter from a complex synthetic wastewater

Abstract

Pharmaceutically active compounds (PhACs) in wastewater effluents pose a threat to both the environment and humanity and, due to disadvantages associated with commonly implemented advanced treatment methods for PhAC removal, it is of interest to investigate advanced biological treatment alternatives for the removal of PhACs from wastewater. Since aerobic granular sludge (AGS) possesses several advantages in comparison to the conventional activated sludge process, it is of great interest to investigate as a new alternative for the biological treatment of PhACs. This master thesis project was a part of the start-up of a PhD project investigating the potential of AGS cultivated in a lab-scale sequencing batch reactor (SBR) to remove PhACs from wastewater. The overall aim of this master thesis project was to successfully cultivate aerobic granules in the labscale SBR, to theoretically evaluate its removal potential of nine selected PhACs and to reach a sufficient reduction of total nitrogen (TN), total phosphorus (TP) and organic matter, expressed as TOC. The performances of the lab-scale SBR were monitored for 29 days by collecting samples from the reactor during different cycle phases and effluent. The dissolved concentration of the investigated contaminants was analysed and the biomass characteristics were evaluated based on the assessment of total suspended solids (TSS), volatile suspended solids (VSS), sludge volume index (SVI), solid retention time (SRT), and sludge morphology by light microscopy. Results showed that the formation of aerobic granules was initiated, but not fully achieved during the observation time. The reactor accomplished nitrogen, phosphorus and, organic removal. High TOC (>90 %), TP (>85 %), and TN (>80 %) removals were achieved by this system. The removal potential of selected PhACs was theoretically evaluated based on relevant findings in a literature review. Overall, it could be concluded that AGS cultivated in a SBR shows potential for the removal of PhACs from wastewater due to the several unique characteristics, such as the easy adjustment of the operational parameters. However, future research is needed to fully determine the potential of using AGS cultivated in an SBR for PhAC removal.