The forces within solid waste landfill must be understood in determining the stability of the foundation ground, structure and solid waste landfill at final waste disposal sites. In particular, pressure from solid waste that forms its structure is important in rattonaly designing that structure. In this research, experiments were conducted on the pressure from bottom ash, incombustible shredded solid waste and mixed solid waste, by using two test apparatuses for measuring earth pressure different forms of foundation. The purpose has to define the pressure transmission mechanism of solid waste landfill. It was found that the horizontal pressure was not proportional to the load pressure in certain types of waste, while vertical pressure from the solid waste showed differences in forms of distribution for each type of waste. Unlike earth pressure, the solid waste pressure fluctuated over time and did not show any distinct active state. The coefficient of stationaly solid waste pressure ranged between 0.38 and 0.46 for bottom ash, between 0.27 and 0.38 for incombustible shredded solid waste and between 0.34 and 0.62 for mixed solid waste. It was also found that these coefficients could not be estimated from the classification based on the grain size distribution of the solid waste. The effectiveness of Poisson's ratio concept in successfully explaining the pressure special characteristics of the transmission was demonstrated.

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In order to utilize the granulated slag from waste incineration residue as construction material, unprocessed slag and slag processed by the magnetic separation/crush/high pH hot water process have been tested for their quality and safety of application. The results are summarized as follows:
(1) Unprocessed slag is not available, because it does not satisfy the standard on particle size, and its quality is inferior to that of river sand. Also, some unprocessed slag does not satisfy the environmental quality standard of soil by the Japan Environment Agency Notification No. 46 on Pb alone.
(2) Processed slag satisfies the fine aggregate standard for concrete and the screenings standard for asphalt, and its quality is equal to that of river sand. Processed slag also satisfies the environmental quality standard of soil for leaching rate of Pb. Therefore, processed slag is suitable for usage as construction material.

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To assess the effectiveness of a leaching test that aims at estimating the release potential of elements, it is necessary to have an understanding of how the major chemical species of objective elements change during leaching. In this study, a sequential extraction (SQE) procedure was employed to evaluate leacheability in a modified availability test (A-test) on As, Cd, Cu, Fe, Mn, Mo, Ni, Pb, Sb and Zn in selected municipal solid waste materials. The degree to which that A-test was effective with respect to the practical potential release limit indicated by the SQE results, and to which that certain chemical speciation form contributed to the released amounts, was quantitatively evaluated by comparing the distribution of different forms of the elements before and after the A-test.
In most samples, the amounts released by the A-test were smaller than the sum of the geochemically extractable fractions obtained by SQE. The A-test under a nitrogenous atmosphere resulted in an increase in the release of As, Sb and Mo, together with Fe and Mn, and a decrease in the release of Cd, Ni, Cu, Pb and Zn. A comparison with the changes in chemical speciation forms subjected to the A-test under different atmospheric conditions, revealed that the difference in release behaviors between the elements was primarily caused by the changes in the moderately reducible fraction, which was regarded as the mixture of Fe and Mn oxides. It is likely that, at least, under the acidic medium (pH 4 ), both the adsorption of cationic elements and the rejection of anionic elements on Fe/Mn-rich oxides are factors controlling mobilization of these elements in municipal solid waste materials when the redox potential changes.

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In this experiment the effects of nitrate and nitrite on the anaerobic digestion process were studied, focusing on the relationship between methanogenesis and denitrification. The seed sludge used for these batch experiments was maintained for more than 5 months. The substrate used for the experiments was skim milk which did not contain nitrate or nitrite. The inhibitory effects of nitrate and nitrite on the methanogenic reaction, using acetic acid as the sole substrate, were approximately the same. The maximum methane production potentials decreased as the COD/N ratio decreased. Methanogenesis did not occur when the COD/N ratio of substrate was lower than 4.6. The conversion rate from nitrate to nitrogen, with acetate as the sole organic source was at its maximum when the COD/N ratio was 15. The conversion rates from both nitrate and nitrite to nitrogen, with glucose as the sole organic source, were at their maximum when the COD/N ratios were 15 and 6, respectively.

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The heat-insulating foam panels of refrigerators contain CFC gas at a concentration four times greater than that of refrigerant CFC gas. To prevent destruction of the ozone layer, there are some places in Europe where they recover not only refrigerant CFC but also CFC gas from the heatinsulating foam panels of refrigerators. On the other hand, Japan has no such facility. We have therefore started developing a CFC recovery apparatus that is suitable for Japanese refrigerators. After various tests, we have built a prototype apparatus that can treat 50 refrigerators per hour. After a one-year test, in which about 8, 000 refrigerators were treated, we have obtained the following results: 1. The recovered CFC-11 is about 400 grams per refrigerator. 2. The recovery ratio from standard panels is 90%.

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To facilitate the design of a cover soil/soil liner system to reduce or remove pollutants from landfill sites, we have developed a model system to estimate the physicochemical characteristics of a soil column, by using the HPLC concept. This system can determine the migration of chemical substances through the soil.
For this system, it was critical to first create a stable soil column. The soil packing method, which is called a pump-pressure switching procedure, is as follows. Water is sent through the soil column by the pump of the HPLC apparatus and, while the pump is still operating the water flow is stopped, by closing the stop valve at the outlet of the soil column. By doing so the soil column is packed tightly in accordance with Pascal's principal. When the pressure reaches its maximum, the valve is re-opened. This closing and opening procedure is repeated every two minutes.
This soil column was applied to saturated percolation flow experiments. We determined the permeability and soil distribution coefficients of chemical substances in various natural soil columns.

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