Bioremediation of Olive Mill Wastewater Using Free and Immobilized Pseudomonas aeruginosa : Efficiency and Phytotoxicity Assessment

Olive mill wastewater (OMW) is a recalcitrant effluent characterized by high organic load, phenolic compounds and lipids, which severely limits its direct discharge or agricultural reuse. This study investigated the effectiveness of Pseudomonas aeruginosa immobilization as a sustainable bioremediation strategy for OMW detoxification. The performance of free cells, agar bead‐entrapped and activated carbon‐fixed cells was evaluated through the removal of chemical oxygen demand (COD), polyphenol, lipids and colour. Free cells, agar‐entrapped and activated carbon‐fixed P. aeruginosa achieved COD removal efficiencies of 41.72%, 79.53% and 83.39%, respectively. Phenolic compounds degradation was enhanced by immobilization, achieving 51.02% with agar beads and 69.91% with activated carbon‐fixed cells compared to 36.51% with free Pseudomonas . Lipid removal increased markedly from 43.54% with free cells to 81.83% with immobilized biomass. Phytotoxicity assessment using Trigonella foenum‐graecum revealed a substantial reduction in OMW toxicity after treatment, reflected by improved germination performance. Among the tested systems, activated carbon‐fixed cells offered a more balanced and operationally stable detoxification system. Overall, bacterial immobilization represents an effective and environmentally sustainable approach for OMW treatment, supporting its potential reuse in agricultural applications.