Removal of pharmaceutical compounds from the liquid phase of anaerobic sludge in a pilot-scale high-rate algae-bacteria pond

This study evaluates the effectiveness of a pilot-scale high-rate algae-bacteria pond (HRAP) to remove pharmaceutical compounds (PhACs) from municipal centrate. The studied PhACs belonged to different classes of synthetic active compounds: antihypertensives, antiepileptics, antidepressants, neuroprotectors, and anti-inflammatory drugs. The HRAP, growing a mixed microalgal consortium made of Chlorella spp. and Scenedesmus spp., was operated in continuous mode (6 days hydraulic retention time) from May to November 2021. Removal efficiencies were high (>85 %) for Sulfamethoxazole and Lamotrigine, promising (65-70 %) for Metoprolol, Fluoxetine, and Diclofenac but low (30-40 %) for Amisulpride, Ofloxacin, Carbamazepine, and Clarithromycin. Propyphenazone and Irbesartan were not removed, and their concentrations increased after the treatment. The combination of abiotic and biotic drivers (mostly global radiation and the synergy between microalgae and bacteria metabolisms) fostered photo and biodegradation processes. Overall, results suggest that microalgae-based systems can be a valuable solution to remove PhACs from wastewater.