Comparative Reduction of Pharmaceutical Hazards in Wastewater among Pilot-Scale Quaternary Treatment Technologies across Seasons

Abstract

For wastewater to provide freshwater resources, reclaimed water should not contain pharmaceutical active compounds (PhACs) or other contaminants that pose significant ecological or health risks. This consideration addresses a recent European Union (EU) wastewater regulation mandating an 80% removal efficiency (RE) for indicator PhACs. We investigated REs of six different quaternary treatment technologies (QTTs) over a year-long study to identify seasonal variability and potential environmental risks of PhACs in recycled water. Wastewater from both a WWTP effluent and subsequent QTT effluents was sampled approximately every two to six weeks and processed by solid-phase extraction, and 12 indicator PhACs were analyzed by LC–MS/MS. Though no RE was observed for ultrafiltration (UF) and limited RE for granular activated carbon (GAC) and GAC + UV, advanced treatment with ozonation (UF + O₃) and reverse osmosis (UF + GAC + UV + RO) achieved over 99% RE for most PhACs during both cold and warm seasons. Probabilistic environmental hazard assessments demonstrated that even after QTT, some PhACs, particularly diclofenac, remained at concentrations that exceeded predicted no-effect concentrations, indicating the need for continued improvement in wastewater treatment and water reclamation strategies.