Barrios et al. Biotechnology for Biofuels and Bioproducts
(2025) 18:48
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press dewatering and paper strength, several challenges remain for industrial-scale adoption. Key concerns include enzyme stability in different pulp formulations, integration with existing mill operations, and potential regulatory and cost barriers. Variations in pulp composition, temperature, and pH, can affect enzyme performance, requiring further research. Scaling up may also necessitate adjustments in enzyme dosing and refining to fit current workflows. Finally, while environmentally beneficial, the economic and regulatory aspects of enzyme and biopolymer use must be carefully assessed. Abbreviations GWP Global warming potential P&PI Pulp and paper industry COD Chemical oxygen demand AOX Adsorbable organic halides HRW Hard-to-remove water WRV Water retention value FBW Freezing-bound water NFBW Non-freezing-bound water HexA Hexenuronic acid SEM Scanning electron microscopy BHW Bleached hardwood kraft NREL National renewable energy laboratory FPU Filter paper unit DNS 3,5-Dinitrosalicylic BCA Bicinchoninic acid polyDADMAC Polydiallyldimethylammonium chloride PVSK Potassium polyvinyl sulfate TAPPI Technical association of pulp and paper industry EMC Equilibrium moisture content PTFE Polytetrafluoroethylene TGA Thermogravimetric analysis DSC Differential scanning calorimetry LCA Life cycle assessment TEA Techno-economic analysis ADt Air-dried ton TIP Technical information paper RB Recovery boiler NB Natural gas boiler BB Biomass boiler MP Medium pressure NG Natural gas FPA Filter paper activity ECF Elemental chlorine-free TCF Total chlorine-free MDSC Modulated DSC SA Sensitivity analysis Supplementary Information The online version contains supplementary material available at https://doi. org/10.1186/s13068-025-02646-1.
A summary of the costs and quantities used for the eco- nomic analysis is presented in Table S10. Calculations on enzyme costs are provided in the supplementary material under section Calculations of enzyme dose per protein content. The cost of enzyme is identified as a key barrier to the application and commercialization of enzyme technologies in the pulp and paper industry. Estimates for bioethanol production suggest that enzyme costs range from 0.10 $ to 1.47$ per gallon of ethanol [55, 111]. In this study, the economic calculation estimated an enzyme cost of 1.82 USD $/ADt of paper product. However, the additional costs of enzyme and starch are offset by the significant reduction in fuel usage, leading to a total net cost change of − 11.29 USD $/ADt, as shown in Table 8. Conclusions and perspectives This study demonstrates the technical, environmental, and economic potential of cell-free enzyme technology to enhance press dewatering efficiency and paper mechanical properties. By reducing energy intensity in paper thermal drying processes, this technology contributes to decarbonization and net-zero goals in the pulp and paper industry. The synergistic integration of mild refining, cell-free enzyme treatments, and cationic starch proved highly effective in improving paper quality while simultaneously lowering the energy required for drying. The application of enzyme treatment, after mild refining, at a concentration of 0.5 wt.% combined with 0.5 wt.% cationic starch resulted in a significant 11% increase in total solids content after pressing and a 25% improvement in tensile strength. Morphological analysis revealed that the enzyme and starch treatments did not significantly alter the mean weighted fiber length and fiber width. However, the reductions in kink and curl indexes indicate increased fiber flexibility and improved inter-fiber bonding, leading to enhanced mechanical properties. The enzyme treatment was shown to reduce hexenuronic acid groups, which influences the water adsorption properties of fibers, as evidenced by a decrease in the water retention value and reductions in hard-to-remove and bound water content. Economic and life cycle assessment results demonstrate the potential of the cell-free treatment as an effective strategy for improving the sustainability and economic viability of paper production. The cost-effectiveness and decarbonization potential of this technology were demonstrated with a total net cost savings of − 11.29 USD/ADt of paper produced, a 12% reduction in GWP, a 37% reduction in emissions from the dryer, and a 23% reduction in direct emissions (scope 1). While this study demonstrates the significant potential of enzyme-based pretreatments to improve
Supplementary material 1
Acknowledgements The authors acknowledge all the partner companies, Domtar, Sappi, International Paper, Smurfit WestRock, and associated team members for valuable discussions throughout this project. In addition, the authors thank Enzymatic Deinking Technologies (EDT) for providing enzyme cocktails. The authors also thank Victoria Kelly, Luke Oates, Allen Stockburger, Thomas Echelberger, and Eduardo Sanchez for supporting standard testing. This work was partly performed at the Analytical Instrumentation Facility (AIF) at North
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