Improving the material efficiency of recycled furnish for papermaking through enzyme modifications

Fibre fines and fibrils within recycled cellulosic pulp have high amorphous cellulose content. These fines, having a high surface area, restrict the free drainage of water and retain bound water within the pressed sheet but contribute little to the hydrogen bonding potential of the fibre slurry. The advantage of higher freeness, achieved by selective hydrolysis of excess fines through enzymes, can be used for enhancement of the drainage rate, leading to increased paper production. In this study, monocomponent cellulase treatment of recycled pulp for drainage improvement as a result of selective and controlled hydrolysis is investigated. The effectiveness of specific types of enzyme activity, endoglucanase or cellobiohydrolase, is studied. The increased solubilization of amorphous cellulose mediated by endoglucanase treatments improved pulp drainability by 11-25%, along with providing better paper properties such as tensile index and smoothness.