Proceedings of the Annual Conference of The Japan Society of Waste Management Experts

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The characteristics of domestic general wastes, including kitchen waste, that was disposed of directly in two landfill sites in about 2000, 1990, and 1980, years ago were investigated. The most suitable of the materials in the landfill site for biogasification treatment were selected and the characteristics of the biogas produced by them were investigated by batch experimental tests.The proportion (by wet weight) of substances that could not be classified (residuals) was largest and the total proportion of waste that was classified as either residuals, paper, or plastics was between 80% and 90%. The residuals and the paper were considered to be the most suitable materials for biogasification treatment as they contained adequate carbon while the plastics contained little easily degradable organic matter.The expected methane generation from the landfilled waste was estimated based on the results of the batch tests, assuming that the biogas was generated from only the paper and the residuals. The estimated values were significantly greater than the amount of methane typically generated from livestock excreta in biogasification facilities. It was demonstrated that biogasification is an utilizable reclamation technology for landfill sites where domestic general wastes, including kitchen waste, have been directly applied to landfill.

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We investigated two-stage fermentation process producing hydrogen and methane from wheat bran and succeeded to produce hydrogen and methane continuously for 3700 hours. Retention of residues in hydrogen fermentation reduced hydrogen production and exhaust of those assisted to produce hydrogen. We found a decline of alkalinity in methane fermentation reactor. Therefore, the addition of protein may be necessary for long-term continuous methane fermentation

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Carbonization device with microwave power has been developed to treat the paper-diaper exhausted by the medical hospital. The moisturized paper-diapers were used as the waste material. In the case that the diapers were installed in the device evenly, the reduction rate was 6% for about 8 hours. On the other hands, in the case that the diaper was installed in a circular copper frame in the device, the reduction rate was performed to be about 3% for 8 hours. In the latter case, it was carbonized uniformly. It was found that it was important for the installation method to treat the waste uniformly.

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The flue gases of 46 waste incinerators were examined to understand the behaviors of nitro PAHs. Only several compounds of nitro PAHs, such as nitronaphthalenes, nitrobiphenyls and 1-nitropyrene, were detected. Concentrations of nitro PAHs were comparable to those of dioxin-related compounds (DRCs), which were two orders of magnitude lower than those of PAHs. Nitro PAH concentrations were positively correlated with those of DRCs and PAHs, suggesting that emission controls of DRCs can also apply to be decline of nitro PAH levels in final exit gases. Concentrations of nitro PAHs in flue gases are reduced by removing the fly ash at bag filter. Combustion temperature and catalyst reaction for NOx emission control do not influence largely the nitro PAH concentrations in final exit gases.

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