Environmental Life Cycle Assessment of a Swedish Dissolving Pulp Mill Integrated Biorefinery

Abstract

The pulp industry plays an important role in the structure of the European economy and society. The production of pulp has been traditionally considered an important source of pollution due to the use of large amounts of chemicals, fuels, and water and its intensive energy consumption. Currently, this situation is changing due to the potential use of biomass to produce value-added products, which minimizes environmental impacts and increases sustainability. This article uses life cycle assessment (LCA) to identify and quantify the environmental impacts associated with a Swedish softwood-based biorefinery where total chlorine-free (TCF) dissolving cellulose is produced together with ethanol and lignosulfonates. The system was defined according to a cradle-to-gate perspective—that is to say, from forest activities to the output of the biorefinery mill. According to the results, forest activities associated with the production of soft roundwood play a minor role in all the environmental impact categories under study. In contrast, the production of chemicals consumed in the cooking and bleaching stages, the sludge treatment generated in the wastewater treatment plant, and the on-site energy production system were identified as the elements that negatively contribute the most to all impact categories. The production of steam from biorefinery wastes, biogas, and methanol in external boilers reduces the environmental impact in all categories. Specific actions associated with the reuse of wastes and improved gas treatment systems would improve the environmental profile of this production activity.