Heavy metal concentrations in the soil surrounding two MSW landfill sites were investigated. At Site-A, the proportion of incineration ash disposed of is high, whereas it is low at Site-B. Incineration ash contains various kinds of metallic elements. Calcium, Zinc, Copper, and Sodium are especially highly concentrated in the ash compared with noncontaminated soil. An 0.1 N hydrochloric acid extraction procedure was adopted to extract those metallic elements from the soil samples, and the extracted solutions were analyzed by atomic absorption spectrometry. As a result, high concentrations were identified in soil samples obtained from the surroundings of Site-A. The kinds of metallic elements detected in high concentrations were the same elements which the incineration ash contains in quantities. And the direction of declining concentration was exactly parallel with the principal wind direction. It was suspected, therefore, that incineration ash had been dispersed from Site-A. The area where especially high concentrations were detected is almost entirely within 30 m of the site. However, concentrations were still slightly high, even at a distance of 100 m from the site. Hence, incineration ash must be treated properly when disposing of it in landfilling operations, to prevent the dispersion of heavy metals.

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On-site Bench scale experiments on the removal of mercury from the flue gas of municipal solid waste incinerators using fly ash were performed at site. The fly ash, which was collected from the electrostatic precipitator without using Ca (OH) ₂ spray and which consisted of only dust derived from refuse, had a high mercury removal efficiency. The removal efficiency was most greatly influenced by the temperature parameter. Fly ash gave a high removal efficiency up to 200°C, but the efficiency dropped quickly at 250°C due to the presence of steam. Both HgCl₂ and Hg⁰ could be removed with high efficiency and even steep peaks of highly concentrated mercury were effectively removed. According to the results of continuous experiments, Hg removal efficiency was more than 85% for 2 hours at 180°C using fly ash.The above experimental results proved that the removal of mercury from flue gas using fly ash was very effective.

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A microwave-assisted extraction (MAE) method was used in the extraction of PCBs and chlorobenzenes from municipal solid waste incinerator fly ash. The highest extraction efficiency was obtained at the conditions of: 120°C of extraction temperature over 50 minutes of extraction time. At the most effective conditions, the efficiency and the precision of the MAE method were evaluated by comparing PCB and chlorobenzene levels to those of the soxhlet extraction and the supercritical fluid extraction (SFE) method, by using eight types of fly ash. MAE seems to be a viable alternative to soxhlet extraction and SFE. However, unburned carbon in the fly ash had a bad influence on the efficiency of the removal of PCBs and chlorobenzenes by MAE. The mutual relationship between chlorobenzenes and unburned carbon in fly ash was sufficiently estimated. As MAE has many advantages over soxhlet extraction, such as a shorter extraction time and a lower use of organic solvent, it is adequate for the extraction of PCBs and chlorobenzenes from fly ash.

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The present study was undertaken to investigate whether compounds (other than unburned carbon) constituting fly ash would facilitate the removal of mercury in flue gas after municipal solid waste incineration. For compounds proven to have such a capacity, the authors examined the mercury removal efficiency under various atmospheric and other conditions, with the goal of clarifying the mechanism by which these compounds facilitate the removal of mercury. When mercury (II) chloride gas passed through the calcined fly ash, containing no unburned carbon, with either 5 % iron chloride or 5 % zinc compounds, calcined fly ash with 5 % zinc sulfide had the highest efficiency of mercury removal, and the mercury removal efficiency with this compound increased as the temperature became lower. The main mechanism was considered to be a fluid-particle reaction between mercury (II) chloride and zinc sulfide. X-ray diffraction analysis revealed that mercury which was removed by the layer of calcined fly ash with 5 % zinc sulfide, assumed the form of black mercury sulfide on the surface of the powder formed.

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A large amount of coal slag, is discharged from coal utilization processes as industrial waste and much of it contains metal oxides which react with acidic gases. Based on this point, we evaluated the suitability of coal slag as a H₂S absorbent at high temperatures (1, 123-1, 273 K, H₂S : 0.7 -1.1%, H₂: 6.3%) in order to develop a new way of reutilizating coal slag.
The following finds were obtained from the present study.
(1) Coal slag has a reactivity for H₂S capture at high temperature. It was found that the sulfidation reaction of coal slag was very rapid at the early stage of the reaction.
(2) The iron component, involved in coal slag, played an important role in sulfur capture. It was not observed that the calcium component in coal slag showed a reactivity with sulfur.
(3) It was clarified that the reactivity of coal slag with H₂S was mainly influenced by the amount of Fe content on the surface of the coal slag particles.
(4) The influence of the temperature on the conversion of iron into iron sulfide was not clearly shown in the range of 1, 123-18273 K.

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To establish a new method of reclamating the coal ash yielded through pulverized coal firing and fluidized bed, we studied how to make effective use of this coal ash as an absorbent of various toxic or, in other ways, detrimental materials, after having applied a simple physical treatment (granulating or pelletizing it) .
The pellet, whose additional amount cf cement is 3 wt%, and whose grain size is approx. 3mm, has proved to have a preferable absorptivity for oils and agricultural chemicals.
Thus, it has been proved that coal ash can serve as an absorbent in soil contaminated by oils and other organic chemicals at disused plant sites or plant sites still in operation, and can help to prevent water pollution from soil contaminated by the spraying of agricultural chemicals on golf courses.

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