Abstract
Pharmaceutical and phenolic contaminants in aquatic environments pose significant environmental and human health risks due to their persistence, toxicity, and resistance to conventional treatment systems. In this study, a halophilic bacterial strain exhibiting a unique dual functionality—simultaneous biodegradation of mixed phenolic compounds and antibiotics along with biosynthesis of cerium oxide (CeO₂) nanoparticles—was successfully isolated and applied for wastewater remediation. The biosynthesized CeO₂ nanoparticles were characterized using UV–DRS, FTIR, XRD, and SEM analyses, confirming a stable cubic fluorite structure with an average crystallite size of ~ 10–13 nm and an optical band gap of 2.5 eV. The degradation performance was evaluated under nanoparticle-assisted batch and reactor treatment conditions, achieving a maximum removal efficiency of 56.53% within 6 h. FTIR and GC–MS analyses confirmed the transformation of complex pharmaceutical pollutants into simpler and less toxic intermediates, indicating effective catalytic–biological degradation. Based on the identified intermediates, a plausible degradation pathway for mixed phenolic compounds was predicted, elucidating the sequential biochemical transformations involved. Ecological safety assessment using phytotoxicity assays with Vigna radiata demonstrated a clear reduction in toxicity and significant improvement in plant growth compared to untreated samples, highlighting the potential of this integrated microbial–nanoparticle strategy as a sustainable and scalable solution for advanced pharmaceutical wastewater treatment. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1038/s41598-026-37427-9.