The leaching behavior of zinc, lead, and copper from fly ash generated in gasification and melting furnaces for municipal solid wastes (MSW) was studied by a constant pH leaching method with organic acids. The leaching degrees of the above-mentioned heavy metals were as low as 10%, or lower at pH 2 for the residue, obtained by leaching fly ash with water. The leaching degree of heavy metals increased remarkably with the addition of organic acids. The leaching degrees of zinc, lead, and copper were 64, 64 and 91%, respectively, under conditions where the concentration of citrate was as low as 0.001 M, and pH was 4. The citrate's effectireness in the leaching of heavy metals may be due to the catalytic acceleration action of dissolution, but not the stabilization effect for heavy metals in solution. The degree of leaching for zinc, lead, copper, and silicate decreased with the elevation of the reaction temperature from 25°C to 50°C. A constant pH leaching method with citrate has features such that high leaching degrees for heavy metals are obtained, and silicate gel, which is difficult to be filtered, is not generated.

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PCB treatment plants have many processes such as dismantlement of PCB contaminated transformers and condensers, extraction of PCB from equipment, and washing of PCB by organic solvent before the PCB decomposition process. In these processes, traces of the PCB and organic solvent are evaporated. The evaporated gases are treated by activated carbon adsorption. However, the breakthrough curve and adsorption characteristics of the mixed gas of PCB and organic solvent are not known. In this study adsorption experiments with mixed gas of PCB (4-chlorobiphenyl or KC 300) and decane onto activated carbon were carried out in a laboratory-scale on-column adsorption apparatus. The results indicated that the gaseous decane had no influence on PCB adsorption, such as the start time of breakthrough and equilibrium adsorption amount due to substitution adsorption. It was suggested that adsorption behaviors of PCB isomers were determined by vapor pressure and the ortho Cl number of each PCB isomer.

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The behavior of lead contained in waste during melt process is considered to be affected by the melting temperature, the heating time, the atmosphere and the content of the main constituents of the ash, such as SiO₂, Al₂O₃, CaO and Fe₂O₃. Experiments were conducted under ambient conditions with oxygen partial pressure down to approximately 5 × 10^-3 MPa, which is easily achievable in actual melting operations. The experimental results also showed that the content of SiO₂ and the other main constituents also have considerable influence.

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In this study, the relationship between the average lifespans and characteristics of twenty-two types of electrical and electronic products was analyzed. Following, the results of this analysis were used to determine average lifespans and the total waste number of products whose lifespan distributions have not been clarified.
The reasons for removing the products surveyed in previous studies were categorized, and four kinds of characteristics : durability, purchase cost, recent improvement in product performance, and ease of transfer of products, extracted as being the main influences on average lifespans for such products. The analysis using quantification theory type I was conducted with data directly or indirectly relating to these characteristics, and average lifespans which were estimated through a questionnaire survey on the products people own. Results showed that the average lifespan for the twenty-two types of products can basically be expressed using the equation of quantification theory with four kinds of data : stock period of functional parts, average shipment value, shipment growth rate and average weight (determination coefficient R² was 0.82). Furthermore, the average lifespan of some products was estimated using the equation of quantification theory. As a result, approximately the same values as those estimated from the questionnaire survey or statistics with mass-balance concept were finally obtained.

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When replacement demand for a product is intensified by measures and policies etc., the lifetime distribution of that product will change, as compared to products that remain in general use. In this paper, a model has been proposed for predicting the total amount of discarded products. These are products in which lifetime distribution has been determined due to a combination of distributions, each independently influenced by measures and policies. This model was then applied in order to predict the number of televisions that would be discarded in the future in Japan, where analog broadcasting is set to be terminated from July 2011.
It was estimated that 47.6 million analog tuner TVs tuner could exist in July 2011 if there would be no termination of analog broadcasting. When the intensification of replacement, due to termination, was taken in to consideration, our model predicted that 34.6 million televisions would be discarded within 7 months around the time of termination of analog broadcasting if 70% of the analog tuner TV holders tended to use the product right up to termination. On the other hand, if the analog tuner TV holders would tend to replace analog tuner TVs before termination, the maximum number of TVs to be discarded per month would be three times as much as that of the current situation.

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In order to produce charcoal with a high specific surface area, the effects of temperature and carbon dioxide in carbonizing atmospheres on the specific surface areas of charcoal carbonized from waste wood were examined. The results were as follows :
(1) The specific surface area of charcoal carbonized at 1173 K in N₂+CO₂ atmosphere from waste wood is 1124 m²/g, which is comparable to that of activated carbon.
(2) The specific surface areas of charcoal carbonized at temperatures of 1073 and 1173 K in N₂+CO₂ atmospheres increase as the yields of the charcoals decrease.
(3) The experimental results revealed that the reaction of C+CO₂ = 2CO promotes and enlarges the specific surface area of the charcoal. Carbon dioxide in carbonizing atmospheres is effective in enlarging the specific surface area of charcoal made from waste wood.

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The adsorption ability of charcoal made from waste wood was evaluated in order to determine whether the charcoal could be utilized as an adsorbent for water treatment. The iodine adsorption capacity, the MB decolorization capacity, the ABS value and the phenol value of charcoals that were produced from waste wood under different conditions were evaluated. As the specific surface area of the charcoal increased, both the iodine adsorption capacity and the MB decolorization capacity increased, while the ABS and phenol values decreased. The adsorption ability of the charcoal increased as the surface area of the charcoal increased. The highest adsorption ability of the charcoals made from waste wood is almost the same as that of activated carbon available on the market.
Pond water purification tests were carried out with waste wood charcoal and with activated carbon that is available on the market. The ability of the charcoal to lower COD and the color unit of the water was higher than that of the activated carbon.

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