Avaliação ambiental do uso da casca de arroz como biomassa para fins energéticos e do coproduto cinza aplicado ao concreto

Abstract

From the precursor idea of sustainable development and the growing concern about the generation of environmental impacts, companies to remain competitive in the market, need to improve their environmental performance, as this becomes increasingly important. With this perspective, Life Cycle Assessment (LCA) has been gaining strength among the tools used to assist in understanding, controlling and reducing environmental impacts, since it identifies the processes that contribute most significantly to the environmental impact of a product throughout its life cycle, offering support in making environmentally sound decisions. As the construction industry accounts for a significant portion of the negative environmental impacts caused to the environment, studies focused on environmental issues are increasingly required and this methodology is included as an indispensable tool for sustainable development of the sector. The rice husk ash (RHA), a residue generated in thermal power plants, has the potential to be used as a co-product in concrete, cement replacement part. In front of the context presented, the aimed to evaluate the use of environmentally rice husks as biomass for energy purposes and gray coproduct applied to the concrete. For the purpose of the work was reached, the significant environmental aspects and impacts of processes combustion of biomass in grate and fluidized bed were raised through a spreadsheet evaluation of environmental aspects and impacts. From the identification of significant impacts the data collection is procedure together to power plants under study. With the support of Software ArcGIS 10.0, mapped the rice processing companies of Rio Grande do Sul, the thermal power plants and concrete producers distant 100 km, 200 km, 300 km and 400 km from the RHA generators. The results show that the replacement of Portland cement with 20% RHA FB contributes to a reduction of about 24% of CO2 eq concrete under study, and the environmental benefits achieved are maintained even with the distant gray 400 km of service concreting plant. As for the concrete produced with 20% RHA GR results showed a reduction of about 7,7% of CO2 eq concrete under study. The results were influenced by the quality of ash generated, which in turn, relates to the biomass combustion processes. The process of combustion of the biomass over the grid promotes the combustion of the shell over various temperature gradients, since the process of fluidized bed combustion, produces a more uniform combustion of biomass, promoted by the relatively constant temperature profile. Thus, the ash generated by the combustion process of rice husk fluidized bed, and reduce emissions of CO2 eq concrete, helps to reduce the consumption of materials used in its manufacture when compared to concrete produced with the ash generated by the combustion process of rice husk grid.