Hybrid photoelectrocatalytic advanced oxidation systems for pharmaceutical wastewater treatment: mechanisms, reactive species, operational parameters, toxicity assessment and real wastewater treatment.

Pharmaceutical micropollutants are persistent contaminants of aquatic systems, with a global survey of 258 rivers across 74 countries detecting pharmaceutical residues on every continent and 25% of sampling sites exceeding safe ecological thresholds. Conventional wastewater treatment provides incomplete removal, necessitating intensified technologies. This review critically evaluates hybrid photoelectrocatalytic (PEC) advanced oxidation processes (AOPs), focusing on PEC coupled with peroxymonosulfate (PMS), peroxydisulfate (PDS), H2O2, electro-Fenton, ozonation, and biological processes. Reported hybrid systems achieved pharmaceutical removal efficiencies of approximately 75-100%. Representative PEC/PMS systems attained 98% sulfamethoxazole removal within 90 min, 100% norfloxacin removal within 25 min, and 91.3% tetracycline removal within 30 min. PEC/PDS enhanced bisphenol A degradation from 65.0% to 85.9% within 60 min, while optimized PDS-assisted treatment produced substantially faster degradation kinetics. In PEC/H2O2 systems, 95% tetracycline removal was achieved within 90 min, whereas electrogenerated H2O2 increased the phenol degradation rate constant from 0.136 to 2.568 h-1. Ozone-assisted PEC achieved 96% cefadroxil removal and 57.6% TOC reduction, while a pilot-scale solar photoelectro-Fenton/ozone process achieved 60% pharmaceutical degradation and 41% COD removal in a four-drug mixture. Bio-PEC hybrids demonstrated 95-99.04% pharmaceutical removal and up to 93% lower energy consumption. These improvements arise from enhanced charge separation and coordinated generation of ˙OH, SO4˙-, O2˙-, and 1O2. Nevertheless, catalyst deactivation, oxidant consumption, mass-transfer limitations, incomplete mineralization, transformation-product toxicity, and energy demand remain critical barriers. Overall, hybrid PEC-AOPs offer highly tunable platforms for pharmaceutical wastewater treatment, but standardized energy, toxicity, mineralization, and long-term stability assessments under real-water conditions are required for practical scale-up.