The elution properties of mercury from weathered granite were investigated by several types of leaching tests, such as the batch type leaching test (Japanese Leaching Test No.46), the pH-dependent leaching test, and the column type leaching test. The effects of elution solvents were also examined using deionized water, leachate from landfill, sodium hydroxide solution, and sodium chloride solution. The results of the batch type test and the pH-dependent leaching test show that the pH of the eluate affects the elution of mercury and that mercury is eluted above pH 10. The column type leaching test demonstrates that mercury in weathered granite is eluted with leachate as well as with sodium hydroxide solution. The concentration of mercury in the eluate increases gradually with the increasing pH of the eluate. The total amount of mercury eluted is 4-5% of the mercury contents of the weathered granite. It is considered that 0H^- accelerates the elution of mercury.

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We continuously monitored Bisphenol A (BPA) and 4-nonylphenol (NP) concentrations in leachate from four kinds of final disposal landfills every week in 2003-2004, and investigated factors related to the volume of leachate. The volume of leachate in each landfill increased with about 300 mm of heavy rain, but the leachate volume was different at each landfill. BPA and NP maintained almost constant concentrations when there was no rain or less than 100 mm of rainfall. However, after 300 mm of rainfall, BPA and NP concentrations in leachate were 10 times higher than the concentration observed before the rain. In addition, BPA concentrations also increased in the dry season (winter) at the landfills that contain leachate. A positive correlation was observed between BPA and NP concentration, but was not observed between these and other measurements, such as pH, BOD, COD_Mn, TOC, electric conductivity (EC) and oxidation-reduction potential (ORP) . We were able to estimate the progress of stabilization in final disposal landfills that have buried waste plastics by monitoring the range of variation in BPA and NP concentrations.

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In order to investigate the effects of repository conditions on slag dissolution, we performed static dissolution tests of simulated molten solidified slag (SiO₂-CaO-A1₂O₃-B₂O₃) specimens that contained small amounts of boron to provide a dissolution index in cement-equilibrated aqueous solutions, deionized water and NaOH solutions at 90°C. The repository for molten solidified wastes consists of many cementitious materials. We found that the slag specimens dissolved more in the alkaline solutions than in the deionized water. We also observed that a calcium silicate hydrate (C-S-H) was formed as a secondary layer on the specimen surface during dissolution in cement-equilibrated aqueous solutions. The formation of C-S-H reduces the alkalinity of the leachate near the slag surface, and it seems to contribute to the long-term continued dissolution of slag through the suppression of Si concentration.

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A continuously operating MSW incineration plant (new plant) established in accordance with the 1997 New Guidelines for controlling dioxins was built near an old operational MSW incinerator (old plant) from the 1970 s. In order to evaluate the reduction of environmental emissions by means of dioxin control technologies, we obtained comparative data on dioxin emissions from the old and new plants under operation and on dioxin concentrations in the surrounding environment. The dioxin emission rate from the old plant was 57 mg-TEQ/day while for the new plant it was only 0.019 mg-TEQ/day. Consequently, the maximum ambient air concentration of dioxins within 5 km of the plants decreased from 0.48 pg-TEQ/m³ to 0.19 pg-TEQ/m³. In addition, the concentration of dioxins in pine needles in the area decreased. We simulated the atmospheric diffusion of dioxins around the incinerators using the emissions data measured at both of them. During the operation of the old plant, the results of the simulated data matched the measured data. For the operating new plant, however, the simulated data was significantly lower than the measured data, indicating that the relative contribution of emissions from the new plant to the surrounding environment is lower.

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The activation energy for the dehydrochlorination reaction on poly (vinyl chloride: PVC) by microwave irradiation has been studied and compared with that of the conventional thermal pyrolysis. The result is as follows: activation energy for the dehydrochlorination reaction by microwave irradiation and conventional thermal pyrolysis is 111 kJ/mol and 220 kJ/mol, respectively. The difference of activation energy between the microwave process and thermal pyrolysis on dehydro-chlorination of PVC seems to be a source of the so-called non-thermal effect in the on microwave irradiation process.

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Waste from scallop organs, called uro in Japanese, contains high concentrations of cadmium. Since uro is rich in high quality proteins and fats, it is expected that high quality fertilizers and feeds for cattle and fish could be produced if the cadmium could be effectively removed. In the present work, we developed a new removal process with the following steps: leaching of cadmium from uro with a dilute sulfuric acid solution of pH 1.5, adsorption of leached cadmium using a gel prepared from apple juice residue with persimmon tannin as a coagulation agent, elution of the cadmium with dilute sulfuric acid, and recovery of cadmium hydroxide as a precipitate by adding sodium hydroxide. In the adsorption by the apple juice residue gel, the pH should be kept higher than 4 to accomplish complete adsorption. In this process, we achieved the pH increase by effectively using peptides and amino acids that are formed by the hydrolysis of proteins in the uro that contain a large number of primary amine functional groups to adsorb hydrogen ions and increase pH. All of the adsorbed cadmium was eluted with 0.1 mol/dm³ sulfuric acid solution and recovered as a precipitate of cadmium hydroxide by adding sodium hydroxide.

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