In order to utilize the slag discharged in the steelmaking process, as road base course materials, several methods including : aging ; addition of chemicals ; and reducing the period of aging ; have been proposed to minimize the deteriorative expansion-disintegration property.
However, slag in which the expansion potential has been minimized by these methods, would not satisfy the criteria of strength (unconfined compressive strength) to be used as base course (hydraulically and mechanically stabilized slag, ‘HMS’), because these methods have a negative effect on the self-hardening property of slag.
Thus, the purpose of this paper is to experimentally evaluate the effectiveness of a newly proposed method in which other by-products (coal ash and sludge discharged from construction work) are added to the slag, in order to minimize expansion potential, as well as to maintain strength development. Results of the expansion and unconfined compressive strength tests, show that the addition of fluidized bed combustion coal fly ash and construction sludge, is considered to be an effective method for improving the property of the slag, as well as enabling the utilization of the mixture for base course construction, as HMS.

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Risk evaluation will be needed for waste materials, such as fly and bottom ash, and leachate (including hazardous substances) . Bio-tests can be available to monitor the total toxicity of waste samples. Because of the contamination of various substances in the waste materials, it is too costly to identify harmful substances. The bio-tests are expected to determine the total toxicity within a short experimental period.
In this research, genotoxicity using bacterial assay, umu-tests and estrogenic cell growth activity using the human breast cancer cells, MCF-7, were applied to elute from ash and leachate samples. Some samples were found to have toxic activity, and the estrogenic cell growth concentration was 10^-8, lower than that of the genotoxicity.

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Melting tests of four kinds of ash, are conducted with a DC type electric resistance heated melting system, being renovated to an actual plant size. The obtained results are examined in terms of changes of material balance and heat balance, from scaling up activity, and in terms of the environmental safety of the system products.
Complete decomposition of waste materials to harmless states through an incineration process is difficult to achieve. However, an addition of a melting process to the incineration process is found to considerably decrease the heavy metal releasing tendency of the slag being formed from incineration ash, and amounts of dioxins released out of the system. Thus, the system demonstrates its capability of harmlessly decomposing waste materials, almost completely. The demonstration tests show prospective practical applications of the system.
Waste gas treatments are indispensable, because large amounts of hazardous materials are contained in incineration ash and fly ash. Potential problems in measures for waste gas treatments for a slag melting furnace, become clearer by conducting experiments with larger equipment. The inherently low volume of flue gas from the developed system, provides flexibility in choosing either a dry process or a wet process for the system, according to possible construction sites. Both of the gas treatment processes demonstrate their compatibility to environmental safety regulations.
The power consumption of the melting treatment of the system is 680 kWh/t-ash for melting fly ash. Furthermore, a design practice is developed, whereby a small scale waste gas treatment equipment is realized.

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A large amount of organic residue containing cadmium is generated and wasted from scallop processing manufacture. In order to recycle the organic residue of scallop mid-gut glands, as, fish meal and fertilizer, a new technology has been developed for removing the harmful cadmium. This treatment method consists of both the process of sulfuric acid leaching, and the process of the electrodeposition of cadmium.
In this investigation, a demonstration plant to enable one batch treatment of about 100 kg/day, was designed on the basis of the results of a fundamental experiment, in which the effects of several factors on cadmium removal efficiency were examined by a small scale test, and a prototype plant was built. Finally, a demonstration test was conducted.
The concentration of cadmium in organic residue from scallop processing manufacture was reduced to 5 mg/kg or less (based on dry weight), by improving the dipping tank in the leaching process and the rectifier in the electrodeposition process, at the demonstration plant. The running cost of operation was reduced by starting the electrolysis of cadmium after a set period of acid-dipping of organic residue, and by clarifying several key notes on cyclic running. Moreover, a final treatment method for electrodeposits such as heavy metals was successfully demonstrated. In this method, the deposits were dissolved in sulfuric acid solution, and recycled as mineral resources.

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Since the operation conditions for measuring of dioxins in flue gas are not optimized in detail, hard work and skill are necessary to measure dioxins. The burden of measurement is one of the inhibiting factors for developing countermeasures to the problem of dioxins.
In this study, an efficient sampling method was developed as one way to address these problems. Recoveries of PCDDs/PCDFs in each part of the sampling trains used in the conventional method and the efficient method were examined. Also, it was clarified that by using the newly developed efficient sampling method, which was composed of only two cooled impingers containing 200 ml water and 300 ml diethylene glycol, PCDDs/PCDFs could be completely recovered. The concentrations of PCDDs/ PCDFs in the same flue gas, sampled using the efficient method and the conventional method, in 4 waste incineration facilities were compared by the authors, and three major analytical companies. It was confirmed that using the efficient method could result in the same or higher data than by using the conventional method, and that the five bottles and the XAD 2 resin used in the conventional method are unnecessary. By this efficient method, preparation and operation of the sampling, the extraction process and the concentration process became drastically easier, and the solvent amounts in the extraction process could be reduced remarkably.
If this developed, efficient method is used, dioxins in flue gas can be sampled and extracted easily not only by analytical companies, but also by incineration facilities themselves, and the measurement costs may be reduced drastically.

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