Life cycle assessment of offset paper production in Brazil: hotspots and cleaner production alternatives

摘要

This paper describes a cradle-to-gate life cycle assessment of offset paper production in Brazil. The production system is classified into two subsystems: a forest production subsystem, which involves seedling production, soil preparation, seedling planting, forest maintenance, and wood harvesting and transport processes; and an industrial production subsystem, involving wood pulp extraction and bleaching, chemical recovery, and offset paper manufacturing processes. The environmental analysis includes the primary energy demand, environmental impact assessment, and land use indicators. The primary energy demand indicated that the largest amount of both renewable and non-renewable primary energy is consumed by the industrial production subsystem, accounting for 91.0% of the total energy demand. The potential environmental impact assessment included eight impact categories: acidification, ecotoxicity, global warming, human toxicity cancer effects, human toxicity non-cancer effects, nutrient enrichment, ozone depletion, and photochemical oxidation. Most of the potential impacts are attributed to the processes of pulp extraction and bleaching, and offset paper manufacturing, mainly due to the production of electricity and thermal energy. As for impacts on land use during the forest activities, a recent developed approach was applied for the regionalized assessment of impacts. Land occupation impacts on erosion resistance, physicochemical filtration, and mechanical filtration showed a reduction in the soil ecological functions, whereas groundwater recharge indicated a credit for the performance of the soil function. With a view to reducing the main life cycle impacts of the industrial production subsystem, an evaluation is made of alternative production scenarios. The best scenario was the substitution of biomass and diesel in the energy generation unit by biomass gasification and optimization of the recovery boiler. (C) 2015 Elsevier Ltd. All rights reserved.