The bromination reactions of inorganic compounds and the properties of the brominated com-pounds formed must be considered thermodynamically to investigate their synergistic effect with brominated flame retardants in plastics, as well as to find alternative synergists to replace antimony oxide. These bromination reactions are also important for the development of debromination agents in the degradation process of plastic waste. In this paper, the vapor pressures of brominated inorganic compounds and the standard Gibbs free energy changes of the bromination reactions of oxides, carbonates and hydroxides are calculated using their thermodynamic data for the discussion of their volatilities and reactivities as flame retardant synergists and also as debromination agents.

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In light of the Containers and Packaging Recycling Law going into effect, amounts and make-up of municipal solid wastes (MSW) will change in the future. Some combinations of MSW disposal methods, such as recycling of containers and packaging wastes, methane fermentation of organic wastes, and MSW incineration, were evaluated under the LCA technique with major evaluation items being in the categories of cost, energy consumption, and CO₂ levels. Results showed that a combination of recycling, methane fermentation, and incineration is the superior method to employ.
Containers and packaging wastes that do not contain plastics are collected separately and then recycled in recycling plants; in the methane fermentation plant, organic-rich wastes are separated mechanically before being treated; and at an MSW incineration plant, mechanically separated burnable-rich wastes and methane fermentation residue are combusted to generate electric power using recovered waste heat.

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Decomposition and detoxification of 2, 4, 5-trichlorophenoxyacetic acid (2, 4, 5-T) and 2, 4-dichloro-phenoxyacetic acid (2, 4-D) as organochlorinated agricultural chemicals and dioxins in fly ash were examined using supercritical water oxidation (SCWO) . The decomposition efficiencies of chlorinated herbicides were more than 99.99% at the conditions of 600°C, 25 MPa, 30 min and an excess hydrogen peroxide ratio of 1.4 (for 2, 4, 5-T) and 1.1 (for 2, 4-D) . The decomposition products of 2, 4-D for SCWO, supercritical water hydrolysis and pyrolysis at 600°C and 30 min were compared. SCWO did not produce any organic products. On the other hand, phenol and other compounds were formed using supercritical water hydrolysis, and polycyclic aromatic compounds along with phenol and others were generated using pyrolysis. For the decomposition of dioxins with SCWO, the decomposition efficiency of each homologue increased along with increased reaction temperature and pressure. Furthermore, there was the possibility that highly toxic tetra- and penta-chlorinated dioxins re-mained as stable intermediates after treatment. More than 99.999% of all kinds of dioxin homologues were decomposed at 600°C, 25 MPa, 30 min and an excess hydrogen peroxide ratio of 10000.

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We conducted a feasibility study to determine whether steam plasma can be used for the treatment of carbonized wastes after pyrolysis. In particular, we investigated the gasification of carbonized wastes to reduce their weight and volume and to produce hydrogen, which is attracting much attention as a new source of energy. In this study, we adopted three thermal plasmas— Ar plasma, Ar+O₂ plasma and steam plasma—as heat sources to treat carbonized wastes. Charcoal was used as the test subject instead of carbonized waste. The results showed that charcoal treated by steam and Ar+O₂ plasmas achieved large weight reductions and that more hydrogen was produced from the charcoal by using steam plasma compared to using other thermal plasmas. These experimental results suggest that gasification, the“water gas reaction”, took place between steam plasma and charcoal.

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A material flow model for spent automotive batteries in Japan was developed, and a survival function of spent batteries stored in households was also determined by questionnaire.
Our Internet questionnaire revealed that the return rates of old batteries were almost 100% at gas stations and vehicle maintenance facilities; about 80% at car parts and accessory shops; about 50% at do-it-yourself stores; and about 85% on the average. About 2.3 million batteries went unreturned annually. About five million spent batteries were stored in households for an average time of approximately 2.2 years thus far. The recycling rates of spent automotive batteries in fiscal year 2003 were estimated as follows: (a) Domestic recycling rate 84%; (b) Domestic dismantling rate (a+ export of dismantled batteries) 87% ; Domestic collection rate (b+export of spent batteries) 89%. The remaining 11% of batteries are exported in secondhand vehicles (5%), incinerated or landfilled, illegally dumped or counted as changes in household stocks.

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The changes of leaching behavior and chemical states for Pb and Cu in various conditions of heat-treated fly ash, which were generated from a gasification melt furnace and stoker-type municipal waste incinerator, were investigated. In this study, chemical states for trace elements on fly ash (e.g. Pb and Cu) were investigated by XAFS spectroscopy at beam line BL01B1 in SPring-8. In the case of agitating fluidized bed heating in air, the leaching rate of Pb and Cu were decreased, and the chemical state of the oxides was estimated and found to be in a more dissolvable state than PbO, CuCI and CuC1₂⋅ 3 Cu (OH) ₂. In heat-treatment in a crucible, the leaching rate of Pb and Cu were not decreased in the pH range 12.5-13.0, and the chemical states of the mixture of chloride and oxide were estimated. We considered that the leaching behavior of Pb and Cu were controlled by oxidizing and forming a dissoluble chemical state when the fly ash was heated under good contact efficiency of gas and fly ash.

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The effect of unburned carbon on the chloride-induced volatilization of heavy metals was investigated using model and molten fly ashes, in the temperature range of 873-1173 K under N₂ gas flowing condition.
As a result, it was found that the volatilization ratio of lead and zinc from the molten fly ash increased with an increase in the temperature. Almost 100% of the lead and zinc were volatilized from the molten fly ash at 1173K. However, the volatilization ratio of lead and zinc from the model ash remained 85% and 25% respectively. It was found that metal oxides in the molten fly ash were converted to metal chlorides of PbCl₂, Pb₂OCl₂, ZnCl₂ and reduced metals of Pb, Zn, Cu by parallel reaction of chlorination with CaCl₂ and reduction with unburned carbon.
Reduction of metal oxides in the molten fly ashes was envisaged in terms of carbon equivalent ratio R_c. Almost 100% of the lead was volatilized at R_c=1.25-13.63 at 1173K. The volatilization ratio of 100% for zinc was also achieved at R_c=13.63. By contrast, the volatilization ratio of copper decreased with an increase in the R_c, resulting in less than 5% of copper volatilization at the R_c greater than 4.0.

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