An environmental life cycle assessment (LCA) was applied to the treatment of inorganic waste water from a research institute by coagulation and flocculation. Three types of waste water was classified and treated in 2002. Global warming potential (GWP) resulting from their treatment was 782kg CO2-eq/m3 for waste water including fluoride, 150kg for the one including heavy metals and 19kg for scrubber waste water. They are greatly different from each other and also far larger than those for municipal waste water treatment that is around 0.2-2kg CO2-eq/m3. In order to understand the implications of these data, a relationship between the water quality and GWP from treatment of the water was derived from the records of this facility. The result indicated that most of the GWP exhaustion can be contributed to the reinforced reagents addition and resultant sludge production owing to the high concentration of fluoride, mercury and arsenic, besides some disadvantage by treating a little quantity, around five to thirty m3 per week. In particular, treating fluoride produces a large amount of sludge, whose combustion produces a large amount of carbon dioxide. Reagents production contributes most to global warming in treating waste water including heavy metals, while sludge treatment contributed most in treating fluoride or scrubber waste water. This difference was explained from the concentrations of three chemicals above using the relationship obtained here.
This study is to propose an evaluation method for resource scarcity using thermodynamic approach. In this study, exergy rent of resource usage is used as a measure for resource scarcity. Based on historical data, the cut-off ore grades, cumulative productions of several minerals, and exergy rent of resource usage could be estimated for different target-time-horizons such as 25, 50, and 100 years. The values of exergy rent are used as characterization values for resource safeguard subjects in LCIA methods.
In order to evaluate the environmental impact of Nagano prefecture industry, we estimated environmental impact substances in Nagano prefecture industry with an input-output table. The four items of environmental impact substances, CO2, NOx, SOx and SPM, were considered. Then we executed environmental impact assessment by using LIME to evaluate total environmental impact of Nagano prefecture industry. As a result of these analyses, the characteristic of environmental impact of Nagano prefecture industry was clarified. Environmental impact of Nagano prefecture industry was greatly influenced by CO2 emission.