Optimization of pharmaceutical effluent treatment by oxidation using laccase-enriched enzymatic extracts from <i>Xylaria</i> sp.

New strategies for effluent treatment aimed at reducing environmental pollutants have significantly advanced, particularly biological methods involving enzymatic processes. In this context, this study evaluated the efficacy of a laccase-enriched enzymatic extract (specific laccase activity = 0.45 U/mg), obtained from the fungus <i>Xylaria</i> sp. for treating pharmaceutical effluents containing paracetamol, diclofenac, mefenamic acid, ibuprofen, and sulfamethoxazole, each at concentrations of 50 ppm. The enzymatic treatment resulted in notably higher degradation efficiencies for paracetamol and mefenamic acid under initial screening (∼70%). These drugs were selected for optimization due to their higher susceptibility to enzymatic degradation and because they are widely consumed pharmaceuticals frequently detected in aquatic environments. Afterward, optimization studies focused on these two pharmaceuticals, employing a statistical experimental design to determine optimal conditions, identified as pH 6.7, temperature of 40°C, and exposure time of 4.5 h. Under these optimized conditions, experimental results indicated a 95.55% reduction in paracetamol and a 55% reduction in mefenamic acid concentrations.Furthermore, enzyme immobilization on chitosan significantly enhanced stability and performance, maintaining approximately 90% reduction of both pharmaceuticals after multiple treatment cycles. These findings highlight the effectiveness of immobilized laccase systems and optimized reaction parameters, supporting their potential application for sustainable and efficient treatment of pharmaceutical effluent. Importantly, this work represents the first demonstration of using <i>Xylaria</i> sp. as a laccase source for pharmaceutical degradation, underlining its novelty and potential.