The leaching properties of slag produced from melting processes were studied to evaluate the effects of melting and its impact on the environment. 24 kinds of synthetic slag and 7 types of slag from different municipal solid wastes (MSW) and furnaces were examined.
Leaching properties of slag were examined for the amount of acid neccessary to keep the leachate at pH4. The chemical stability of slag given by the amount of acid corresponded well with the chemical components and texture of the slag. This leaching method was useful to evaluate the effect of melting and its impact on the environment.
Slag which had homogeneous amorphous texture and low basicity (CaO/SiO₂<0.7) was chemically stable and was only slightly affected by the melting process and the characteristics of the MSW.

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If it is possible to regenerate spent cooking fat and oil back to a grade which is utilizable as food, the discharge of the former could be decreased, leading to the protection of resources and the environment. Therefore, chitosan-gel beads containing activated carbon and alkali, which have been developed on the purpose of regenerating spent fat and oil, were used in regeneration treatment experiments that were conducted for many materials originating from various sources.
As a result, by means of very simple treatments, acid value (AV), which is an index of the deterioration of fat and oil, decreased, and the reduction of discoloration and odor was observed.Furthermore, it turned out that the change of water content, POV (peroxide value) and IV (iodine value) was small, and therefore this method was suitable as a method of regenerating spent cooking fat and oil on a small scale, such as in household use.
For the purpose of increasing the treatment efficiency, research on the preparation and reaction conditions of the chitosan-gel beads was conducted. Crushing the chitosan-gel beads and/or keeping the moisture content in the range of 50-65% were suitable methods. Further, the reaction rate was increased by warming and/or stirring. The same effect was also observed when agar was used instead of chitosan, i.e., in the case of agar-gel beads containing activated carbon and alkali.

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In this study, we analyzed the determinants of waste reduction through variable rate programs. The major conclusions of the study are as follows:
1) The main factors in combustible waste reduction through variable rate programs are two-tier pricing and the price of waste bags. The introduction of waste paper recycling simultaneously with variable rate programs also significantly influenced waste reduction for the year in which they were introduced.
2) Even where the influence of high prices of waste bags is excluded, two-tier pricing programs are shown to promote waste reduction.
3) Waste paper recycling and variable rate programs reinforce each other to promote waste reduction.

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The volatilization of such heavy metals as Pb, Zn, Cu and Fe in MSW (Municipal Solid Waste) molten fly ash was studied by applying HCl gas, converting these heavy metals into metal chlorides. As a result, volatilization of more than 98% of Pb and Zn was achieved for both MSW molten fly ash and MSW fly ash at 1173 K. The volatilization of Fe was 85% and 100% for MSW molten fly ash and MSW fly ash at 1173 K, respectively. The volatilization of Cu was lower than other metals in both fly ashes.
The effects of temperature and quantities of Na and K in the MSW molten fly ash on the volatilization of heavy metals were investigated, by employing model fly ash prepared under different treatment temperatures and mixing weights of Na and K. As a result, it was found that there was no significant difference in the volatilization of Pb, Zn, Cu and Fe for the treatment temperature of the model fly ash. Only Fe volatilization decreased with the increase of Na and K content. This result corresponded with the results of Fe volatilization for MSW fly ash and MSW molten fly ash.

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Understanding current and future contaminant distributions is very important in carrying out counter-measures for remediation of soil and groundwater contamination. In the present circumstances, the contaminant distributions are estimated by using contaminant concentration data at boreholes. However, in many of the considered cases, the estimation is a result merely obtained by interpolation of scattered data, and does not always show overall contaminant distributions. This study tried to determine an overall contaminant distribution by applying numerical simulations and resistivity methods. The latter involves electric investigation and is expected to estimate the relative distribution of contaminants in a site contaminated by waste materials. The distribution of contaminants estimated by numerical simulation was shown to be similar with that estimated by the resistivity method. It is suggested that the numerical model could reveal the current distributions of contaminants in groundwater. The future distribution of contaminants estimated by the numerical model suggests that countermeasures for soil and groundwater contamination at the site are necessary.

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To develop a more applicable means to screen for toxicity, we have selected a battery of three biotests for a six-month monitoring period of the risk in leachate from a landfill site. To validate this battery, we measured genotoxicty, proliferation activity of MCF-7 and cytotoxicity of leachate, its treated effluent and receiving river waters once a week. A new measure, named Negative Dilution Factor (NDF) become apparent from umu-test. In the experiments genotoxicity was detected in leachates, and reduced through the treatment process. Leachate showed same seasonal changes in proliferation activity of MCF-7 cells in river samples. Since the average proliferation activity of MCF-7 cells in leachate was low, there may be little effect of leachates on the river. Cytotoxicity of leachate and treated effluent were stronger than river water but almost all of these toxicities were less than 50% inhibitiing. Cytotoxicity was observed in concentrated samples from a landfill site, but it derived from osmotic pressure by salinity. As the maximum cytotoxicity of treated effluent was 9 times that of upstream samples, it may be necessary to dilute treated effluent about 10 times for the management of impact on the environment.

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This study aims to build consumer behaviour models which can analyze changes in consumer behaviour when deposit systems are introduced in the collection of empty cans and bottles. First, consumer behaviour models using three kinds of methodology (the refund method, the encouragement method and the conbination method) in deposit systems are derived from utility maximization thoery. Second, parameters in the models are estimated using data gathered through a consumer survey. The survey, consisting of a questionnaire, also investigated the effects of deposit systems. The estimates produced three model, which provied to be sufficiently significant statistically. The models found satisfactorilly explain and predict the number of cans and bottles to be purchased as well as to be returned when deposit systems are introduced. These models can be applied to analyze the benefits to consumers, local governments and enterprises arising from the introduction of deposit systems.

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For concrete waste recycling, data for energy consumption were collected and the effect of concrete waste recycling on the reduction of emission of pollutants (CO₂, NOx, and SOx) was evaluated using LCA methods. From the results, energy consumption unit for machine in the production process only had a size effect. The coefficients of variation of energy consumption units between the firms investigated were 30-70%, except for the landfill site construction process (108%) . Concrete waste recycling was effective for the reduction of pollutants only if in the recycling process electricity was used for the plant and light oil for machines. The amount of the reductions were 0.52 kg-C/ton, 2.2×10^-3 kg-NOx/ton, and 3.5×10^-3 kg-SOx/ton. The processes which contributed to emissions were mainly transport process and machines used in the recycling process. For all the pollutants, the annual amount of emissions from the recycling and disposal of concrete waste was negligible compared with total emissions in Japan. This means that the increase in the emission of the pollutants with the increase in the recycling of concrete waste should not limit the recycling of concrete waste.

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Components and quantities of commericial waste generated vary according to the source and the nature of the commercial activity. In this study business establishments are classified into 11 groups according to business activity. A simple method for estimation of waste generation, recycling, and its composition for each group was then developed. Unit waste amounts per worker are determined for each group by modifying the exising results obtained already through a survey carried out by the city of Sapporo. By multiplying the number of workers, which is easily accessible through general statistics on business activity, waste stream is then calculated. The unit values used in this study and estimated amount or composition were confirmed by comparing these results with those of other studies. The accuracy of the model was checked by the estimated disposal amount for 104 cities. As an example to show the usefulness of the model, an application for a recycling plan is also demonstrated.

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The socio-economic impacts of siting landfill on residents living in surrounding areas is examined and, using conjoint analysis, public attitudes are investigated. Conjoint analysis is a multiattribute preference-elicitation technique based on a contingent choice survey. We conducted a questionnaire survey of some residents in Morioka city, Iwate prefecture in Northern Japan. By our empirical study, we find out that people are opposed strongly to siting landfill in areas which are sources of drinking water. Waste disposal, including industrial waste, and the expansion of areas for waste disposal are also found to have undesirable effects on the community. In particular we find out that the impact of disposing industrial waste originating in metropolitan area but disposed in Iwate prefecture exceeds the negative effects of siting landfill in drinking water sources. In addition, we find out that adjacent residents evaluate more positively the further away they are from a landfill. The increase in utility is observed to be up to approximately 4.72 km.

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