Recycling of plastics has been attracting much attention in Japan and also in foreign countries. Recycling system is not easily introduced mainly due to its expensive cost. Economic evaluation of recycling, however, has not been fully investigated in Japan. In this study, fractionation, collection and processing of plastic waste in the residential and commercial sectors are taken into account. Especially the plasticswaste collection has been modeled quantitatively by using the regional mesh statistics and the reports on office survey provided by the Japanese government. Various kinds of plastics-recycling processes are evaluated from the viewpoint of both of life-cycle energy and economics. The evaluation results can be summarized as follows:
The PET reclamation has good performance of energy saving. However, it takes a lot of cost for collection, and this technology is not economically acceptable even if the recycled resin has the same value as the virgin one. Some simulations show that cost reduction is possible by decreasing the labor hour for plastics collection. Furthermore, some measures for voluntary collection of PET containers are most effective if the government thinks the plastics recycling is preferable from the viewpoint of the local and global environment.

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The selectivities of ring opening were investigated for the hydrocracking of phenanthrene and anthracene under an initial hydrogen pressure of 6 MPa, at the temperature of 430°C and in the time range from 30 to 120min. Major products from phenanthrene were hydrogenated phenanthrenes, butylnaphthalenes, butyltetralins and hydrogenated anthracenes. Major products from anthracene were also hydrogenated anthracenes, butylnaphthalenes, butyltetralins and hydrogenated phenanthrenes. Isomerization was considered to proceed between 1, 2, 3, 4, 5, 6, 7, 8-octahydrophenanthrene and 1, 2, 3, 4, 5, 6, 7, 8-octahydroanthracene via 6-butyltetralin intermediate: 6-butyltetralin intermediate will preferably recyclize to make octahydrophenanthrene or octahydroanthracene before it desorbs from catalyst surface, and between 1, 2, 3, 4-tetrahydrophenanthrene and 1, 2, 3, 4-tetrahydroanthracene via 2-butylnaphthalene intermediate: 2-butylnaphthalene intermediate will preferably recyclize to make tetrahydrophenanthrene or tetrahydroanthracene before it desorbs from catalyst surface.
Ring-opening products were classified into the following two components: 1-buthylnaphthalene derivatives and 2-buthylnaphthalene derivatives. Selectivity to 2-buthylnaphthalene derivatives in phenanthrene reaction was higher than that in anthracene reaction.

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The composting of garbage has been expected to reduce the amount of waste disposal in landfills and to improve the efficiency of power generation combined with refuse incinerator. In this study, the composting of garbage discharged from three stores in CO·EOP Tokyo was researched, and the inventories of the composting system and the incinerating system were investigated from the viewpoint of environmental loads such as energy consumption and solid waste.
In the results obtained from the composting research, the electricity consumed by the composting of garbage was large in autumn and winter season, and it was ascertained that the electricity consumption was reduced by adjusting the amount of garbage to the capacity of the composting apparatus. The results of the inventory analysis showed that energy consumption in the composting system was larger than that in the incinerating system. The solid waste (incineration ash) in the incinerating system was larger than that in the composting system, because the compost was finally used in the farm.

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