We reviewed the factors influencing leaching tests for hydrophobic organic pollutants (HOPs) by conducting a review of recent research carried out in Europe on HOPs and studies on the leachability/mobility of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and dioxins (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans; PCDDs/DFs) . Based on the review, we suggest the requirements for valid leaching tests for HOPs considering the evaluations of risk and quality of municipal solid waste residues and products recycled from them. Factors that we exawined were the quality of experimental materials, leaching time and contact method, leachant matrix, solid-liquid separation method, temperature, solid-liquid ratio, sample size, volatilization and photodegradation. And, with the viewpoint of establishing satety standards for leaching tests, we also exawined the conformity with water environmental standards, the assumed environmental conditions and regulation levels.

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The wide area collection of waste decreases by-products such as dioxins and reduces the environmental damage with efficient recycling. However it may increase environmental costs through waste transportation and facility construction. The introduction of wide area treatment has required long distance transportation and the large-scale construction of treatment plants. In this paper, we built 18 scenarios and estimated the environmental costs arising from transportation, processing, resource recovery and final disposal. In the wide area collection, we estimated that environmental costs falt with thermal recycling and material recycling. As the result, we found the thermal recycle was more effective for reducing environmental costs. Material recycling can also decrease energy consumption, however, high levels of quality control are required to extract high quality resources from such recycling. On the other hand, even though the increase of environmental costs through transportation in the wide area collection system is not that high in view of the whole system, an efficient collection and transportation system is needed for an appropriate separation.

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Melting of solid waste incineration ash, which vitrifies the ash through thermal treatment, is expected to be an effective recycling technology. In this study, the effects of the composition of the main ingredients of ash (SiO₂, CaO, and A1₂O₃) in artificial ash (SiO₂-CaO-Al₂O₃ Fe₂O₃ Na₂O-P₂O₅ PbO) on the following properties were investigated, 1) the melting characteristics of ash from an economic perspective, 2) the physical strength of melted slag as a measure of its quality, 3) the leaching characteristics of a heavy metal (Pb) from melted slag in view of environmental safety.
Melting characteristics were evaluated by a method of microheating (JIS K 2151) . The lowest hemisphere temperature was found at basicity (CaO/SiO₂) of 0.54 -1.07 with an Al₂O₂ ratio of about 10 mol%. The physical strength of slag was evaluated by an abrasion test. The strength had a close relationship with the crystallinity of the slag, and the weight loss of crystallized slag was much lower that of uncrystallized slag. Pb leaching concentration was more than 1 mg/L at basicity of 0.53-3.2 with Al₂O₂ ratio of 6-15 mol%.
In conclusion, the properties were greatly influenced not only by basicity but also by a change in the Al₂O₃ ratio, and trade-off relations in the properties were observed. Therefore, the optimum composition range of ash should be determined according to the purpose of reuse.

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Poly aromatic hydrocarbons (PAHs) contained in fly and bottom ash, their leaching characteristics and absorbance into ash and estorogen-like cell growth activity caused by the elution from the ash were investigated in order to evaluate the effect of these ashes on the leachate and the water quality at the site. The leaching of PAHs having less than 4 rings was observed. It was found that these compounds could be absorbed into ashes and sediments. The concentration of PAHs in the leachate was determined to be very low and there was only a trace of the PAHs in the sediments around the outlet of the leachate treatment facility. These compounds were removed through treatment processes with coagulated-sedimentation, biological treatment and sand filtration with activate carbon adsorption. The estrogen like growth activity of MCF7, a human breast cancer cell line, on the PAHs included in bottom ash was about 50% of the theoretical prediction.

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Wood chips are used as the base material for many marketed commercially garbage processors currently. However, the composting of wood chips requires a long time, because they require a long time for degradation. Therefore, in order find a new base material, the suitability of 23 kinds of materials was examined. The test substances were mainly agricaltural materials. As a result, we were able to classify the characteristics of materials to be used as the base material for many types of garbage processors.
4 kinds of materials (bark compost, crushed coconut shell (Berabon), vermiculite and a moisture absorbent additive) were mixed. 16 mixtures were made from these materials and the suitability of these mixtures as base materials for an electric garbage processor was examined.
Data were measured of 3 stages (early, middle, latter term) of this investigation and analyzed. The results show that the bark compost controlled the pH and decreased the emission of ammonium gas, while crushed coconut shell maintained the stirring efficiency throughout all stages of the decomposition. It was shown that vermiculite increased the emission of ammonium gas and decreased the stirring efficiency. The moisture absorbent appeared to affect these factors, but this effect was limited to the middle stage.
In conclusion, it was shown that a mixture of bark compost and crushed coconut shell is an efficacious base material for electric garbage processors. As a result of further investigation into the ratio of bark compost and crushed coconut shell, it was shown that mixtures consisting of 1/4 or more bark compost and 1/4 or more crushed coconut shell were suitable as base materials for electric garbage processors.

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For the purpose of recoveing valuable metals from heavy oil ash, a process of recovering vanadium and nickel from heavy oil ash was developed. Learding from the ash collected from the electrostatic precipitator of power plants and the separation of metal ions from leach liquor were examined. The process mainly consists of leaching, solvent extraction and crystallization. Vanadium and nickel are leached by a hydrogen peroxide aqueous solution. Vanadium is extracted by a TOMAC-xylene solution followed by stripping to aqueous phase in an alkaline condition. Nickel is extracted by HNAPO-kerosene is an acid condition. Adding ethanol results in vanadium and nickel deposition separately.

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We showed that the use of a rotary membrane separator for activated sludge filtration is superior in terms of energy-saving efficacy and endurance. By using a micro strainer with a diameter of approximately 45μm, the separator let plugging substances, which disturb the separation efficiency, pass through the membrane easily. The system was capable of controlling the degree of the formation of the cake layer. As a result, the resistance of filtration was remarkably low and the separation could stand for a long period.
Basically, this system is a sludge separat or utilizing cake separation. However, it can avoid sludge consolidation by controlling the differences in the separation pressure between 1 and 2 kPa. Furthermore, the use of a rotary membrane separator could limit or prevent the build-up of cake layers by increasing the shee stress due to the rotation of the micro strainer. The result of the experiments with a stainless steel screen (pore size 45 μm) which is for hydrophobic treatment on its surface showed that we can maintain the sludge separation process stability with a simple brush washing twice every three months and the water treated by this method is clean enough (SS and TOC concentration is about 10 mg/L) .

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This paper investigates the use of taxes on virgin materials, and subsidies on recycling activities as economic instruments to provide firms with incentives to re-use recyclable materials collected by local governments. Using a partial static model, we first derive conditions under which each instrument leads to waste reduction, and show that they depend on the elasticity of demand for recycled goods and on the waste coefficient. Secondly, a examination of the optimal fee structure for accomplishing a given level of waste reduction shows that a combined tax on goods and a re-use subsidy proportional to the waste coefficient is an efficient and feasible method for reducing waste.

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Emission characteristics of ammonia (AM) and methyl mercaptan (MM) as odorants from the biological decomposition treatment of organic wastes were investigated experimentally using a high-temperature decomposition apparatus with a semi-sealed air circulation system. In result, it was found that the time dependent characteristics of both components in the batch processing were based on changes of their apparent Henry's law constants (H') and pH. Long-term decomposition experiments under the repeated input of dog food (DF) or prepared kitchen refuse (KR) showed that Am concentration in circulated air of the apparatus rapidly rose at around pH 8 or more with the accumulation of ammonium types of nitrogen and an increase of H' with pH. However pHs of two kinds of microbial beds differed at the same magnitude of accumulated NH₄-N concentration because of their alkali buffer capacities. On the other hand, there was a correlation between MM and carbon dioxide concentration in the circulated air in the processing of the DF, and it was supposed that differences of MM concentration between DF and KR were dependent upon their protein contents. The analysis of the mass-balance of nitrogen in the processing of DF made it clear that contained nitrogen was decomposed and converted into NH₄-N which accumulated in the microbial bed at lower pH but released as the pH rose up to a stable range.

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In this study, we examine factors driving illegal dumping, based on surveys of cities with variable charges on waste disposul. We found that about 40% such cities experienced an increase in illegal dumping and about 90% of these cities had an ongoing problem. A further finding is that in two municipalities the increase in illegal dumping amounted to less than 1% of the total decrease in combustible waste. Those municipalities with illegal dumping problem before the introduction of variable charges fended to be the same municipalities with increase of illegal dumping after the introduction of varlable charges. In addition, among municipalities that had an illegal dumping problem prior to the introduction of variable rates, those that introduced separate collection systems at the same time tended to see a rise in illegal dumping. The incidence of illegal dumping was also higher in municipalities where the price of waste bags was higher, although this factor was not statistically significant.

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