Enhancing the Repulping Efficiency of Enzyme-Treated Wet-Strength and Hard-Sized Wastepaper

Abstract

Effects of mechanical refining parameters and enzymatic treatments were studied relative to the repulping efficiency of four wastepaper grades: kraft grocery bag (KGB), double-lined kraft (DLK), American old corrugated container (AOCC), and Korean old corrugated container (KOCC). Parameters including freeness, fiber length, fines, flake content, and specific energy consumption were examined under varied conditions. Optical microscopy confirmed that narrowing the mechanical disperser gap increased fiber disintegration intensity, reducing freeness and flake content but raising energy consumption. A synergistic effect was demonstrated between optimized mechanical refining and enzyme formulations (Cell E-B), specifically targeting wet-strength and hard-sized wastepaper. Instead of directly degrading chemical additives, the cellulase-based treatment facilitates fiber recovery by partially hydrolyzing cellulose at the fiber surface and disrupting fiber–additive interactions. This enzymatic action promotes fiber swelling and liberation, leading to further reductions in freeness and flake content while preserving fiber length. These findings provide comparative insights and actionable data to support the transition from laboratory findings to planned full-scale industrial manufacturing, offering pathways for energy savings and improved fiber utilization in the paper recycling industry.