マテリアルフロー分析による日本におけるガラスのリサイクル可能性評価

Abstract

Objective. In this work, a dynamic material flow analysis (MFA) for glass in Japan in the period of 1978-2008 was conducted to estimate the stock in-use of glass and their recycle potentials. Glass was categorized into glass bottle, glass sheet, and glass fiber products. Time series data about the consumption of the glassware in end-uses, i.e. automobile, buildings, machinery, etc. were estimated. Then, the dynamic MFA for each glassware was conducted, in which the life time distributions for the end-uses were taken into account. A top-down approach and a bottom-up approach were used to estimate the stock in-use of glass. The results obtained by both approaches were compared to validate the data used for dynamic MFAs.Results and Discussion. It was estimated that the stock in-use of glass sheet in buildings and automobiles were 30 million tons and 2.5 million tons in 2008, respectively. The results obtained by the top-down approach and bottom-up approach were moderately coincident during the investigated period. The amount of glass contained in end-of-life products in Japan has monotonously increased during these decades. The glass sheet was the largest among the discarded (landfilled) glass, which was 634 million tons in 2008.Conclusions. Our results showed that there is a substantial stock in use of glass, especially, glass sheets in buildings and automobiles. Further work shall be done to investigate the technological and economical feasibility of recycling glass sheets from the end-of-life products as well as the reduction potential of environmental impacts by the recycling of glass sheets.