Optimization of color, lignin, and total phenol removal from pulp and paper wastewater using immobilized laccase: a Taguchi approach

Abstract

This study investigated the optimization of color, lignin, and total phenol removal from pulp and paper wastewater with immobilized laccase from Trametes versicolor on titanium dioxide nanoparticles. A Taguchi L9 orthogonal array design was used to efficiently investigate the impacts of four essential factors: catalyst concentration, pH, reaction temperature, and reaction time, each of which varied over three levels. The immobilized laccase's performance was examined by assessing the reduction in color (Pt–Co), lignin (mg L⁻¹), and total phenols (mg L⁻¹ GAE). The results demonstrated remarkable variations in the reduction of pollutants, highlighting the significance of the selected parameters. The best combination of factor values for simultaneous elimination was found using S/N ratio analysis, with time having the greatest impact. The regression models for lignin removal showed the strongest predictive power, with R² values of 98.23% for free laccase and 94.41% for immobilized laccase. All of the models were validated to be statistically significant. Immobilized laccase outperformed free laccase with removal efficiencies of 94.01% for color, 95.45% for lignin, and 94.25% for total phenols compared to the lower removal rates of 64.46%, 58.32%, and 52.65% observed respectively for the pollutants. This study demonstrates the Taguchi method's effectiveness in optimizing pulp and paper wastewater treatment with immobilized laccase, offering valuable insights for efficient and cost-effective pollutant removal.