We investigated the composition and impurities of waste cooking oil discharged from households and restaurants. Though the characteristics of oils discharged vary greatly between individual sources, we verified that the process of collection and accumulation results in homogeneous oil mixtures. We analyzed the correlations of (1) acid values and free fatty acids, and (2) iodine values and saturated fatty acids as indices of the deterioration state and major composition of waste oil. Furthermore, concerning the relationship of waste oil quality and its conversion to fuel, we confirmed that in ester conversion and washing processes (1) the flash point decreases and kinematic viscosity improves, (2) the fatty acid constitution and iodine value is maintained, and (3) free fatty acids, acid values, metals, and inorganic chlorines decrease. In addition, we determined through our analysis that the residual glyceride quantities in the oil, a primary factor in biodiesel fuel quality, are affected by differences in kinematic viscosity, CFPP and carbon residue (based on a 10% distillation residue) . In order to promote biodiesel fuel conversion, a standard for waste cooking oil was determined that consists of acid value, iodine value, saturated fatty acid, water content and impurities.

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Differences in images of a Cycle-Oriented Society were preliminarily discussed by reviewing words that are similar to a Cycle-Oriented Society and their English translations. Existing images of a Cycle-Oriented Society were then compared and analyzed from three points of view, and their relevance to the concept of sustainable development was discussed.
The following conclusions were drawn: 1) The word cycle comprises meanings that include natural cycles, material cycles in an economic society, virtuous cycles of the environment and economy, and cycles of relationships and lives; 2) A Cycle-Oriented Society has two objectives. These include environmental conservation or reduction of environmental burdens, and restraint of natural resource consumption; 3) The existing images of a Cycle-Oriented Society differ slightly when meanings contained in the word cycle, objectives of a Cycle-Oriented Society, and field of measures to attain these objectives are compared. Meanings for the word cycle and the objectives of a Cycle-Oriented Society are closely related to the concept of sustainable development. They affect the field and contents of measures. Consequently, these must be clarified for discussion of a Cycle-Oriented Society.

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A mathematical model was developed to evaluate the dynamic performance for component elements of solid waste in the municipal solid waste management system. The component elements in consumer products, solid waste, and incinerated ash were determined using an X-ray fluorescence spectrometer and the neutron activation analysis method. After gaining validation of the model by comparing model estimates with the observed, the flow and stock performances of the component elements in the municipal solid wastes system were evaluated, including variation characteristics using Monte-Carlo simulations. The model was applied to delineate quantitatively how component elements were transported and accumulated in the Kyoto city municipal solid waste management system.

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In this study, we evaluated the economic benefits of the introduction of household garbage disposers. Our main conclusions are as follows. 1) In the case of large cities, use of apartment building disposer systems in combination with wastewater treatment equipment is more appropriate than the use of direct discharge disposers. Increased user expense is assumed to be counterbalanced by the value of user benefits. 2) Direct discharge disposer use is more appropriate than system usage in smaller cities. Direct discharge disposer use must be permitted only when the discharged wastewater is treated at the same levels as before introduction. Moreover, consensus is necessary regarding recovery of increases in wastewater treatment costs.

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Adsorption gel for metal ions was prepared from wastepaper by immobilizing primary amino groups by means of chemical modification. From the elemental analysis of the gel, it was found to contain a functional group as high as 4.1 mol/kg-dry gel. Adsorption behaviors for some base metals such as copper (II) and chromium (III and VI) in the pH region as well as precious metals such as gold (III), palladium (II) and platinum (IV) from hydrochloric acid were examined and compared with commercially available weakly basic anion exchange resin. Concerning the adsorption of base metals from the pH region, the order of the selectivity among metals tested was as follows: copper (II) >chromium (VI) >iron (III) >>zinc (II) >chromium (III) . On the other hand, gold (III), palladium (II) and platinum (IV) were quantitatively adsorbed over the whole concentration region of hydrochloric acid, while iron (III) and zinc (II) were not practically adsorbed. The selectivity to precious metals of the gel was found to be higher than that of the anion exchange resin. The maximum adsorption capacities for palladium (II), platinum (IV) and copper (II) were 1.6, 1.1 and 0.48 mol/kg-dry gel, respectively.

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