Use of Permeable Reactive Barriers in the Removal of ACT and DCF from Effluents of Wastewater Treatment Plants

Pharmaceuticals such as paracetamol and diclofenac (DCF) are among the most extensively consumed drugs worldwide and are continuously released into municipal and hospital wastewater due to incomplete human metabolism. Their persistent presence in aquatic environments, typically ranging from ng/L to µg/L, raises concerns due to endocrine disruption, chronic toxicity, and the promotion of antimicrobial resistance. Conventional wastewater treatment plants (WWTPs) remove 70–90% of ACT but less than 30% of DCF, primarily because these systems were not designed to target low-concentration, recalcitrant micropollutants. As a result, pharmaceuticals frequently pass into treated effluents, highlighting the need for advanced, sustainable, and passive treatment solutions. Permeable reactive barriers (PRBs) have emerged as a promising technology for the interception and removal of pharmaceuticals from both wastewater treatment plant effluents and groundwater. This review provides a comprehensive assessment of ACT and DCF occurrence, environmental behavior, and ecotoxicological risks, followed by a detailed evaluation of PRB performance using advanced reactive media such as geopolymers, activated carbon, carbon nanotubes, and hybrid composites. Reported removal efficiencies exceed 90% for ACT and 70–95% for DCF, depending on media composition and operating conditions. The primary removal mechanisms include adsorption, ion exchange, π–π interactions, hydrogen bonding, and redox transformation. The novelty of this review lies in systematically synthesizing recent laboratory- and pilot-scale findings on PRBs for pharmaceutical removal, identifying critical knowledge gaps—including long-term field validation, media regeneration, and performance under realistic wastewater matrices—and outlining future research directions for scaling PRBs toward full-scale implementation. The study demonstrates that PRBs represent a viable and sustainable tertiary treatment option for reducing pharmaceutical loads in aquatic environments.