Degradation of pharmaceutical contaminants in sewage wastewater using biosynthesised nanoparticle produced by halophilic bacterial strain and phytotoxicity

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.