Available amounts of calcium and major components in bottom ashes and fly ashes from municipal incinerators were examined to determine their influence on calcium scale formation in landfill sites. All of Ca (OH) ₂and CaSO₄contained in ash samples could not leach by the batch leaching test with low liquid/solid ratios (eg.10) because of their solubility restrictions. A liquid/ solid ratio of 200 is recommended to obtain total soluble calcium. Free alkali could be determined by acid titration curve. Fly ashes with Ca (OH) ₂spray largely influence on calcium scale formation because of soluble calcium and free alkali.
In addition, completely burned ashes are liable to leach two components. Calcium scale has been found at 5 out of 15 landfill sites. Three cases might be caused by highly alkaline fly ashes, and the other two by bottom ashes.

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The use of sulfur-oxidizing bacteria (SOB) in corporation with granular activated carbon (GAC) to treat photo-processing waste (PW) has been established as one of the most effective options. Breakthrough behavi or of GAC during the continuous treatment using an SOB/GAC system was studied in this paper, in which a hypothesis has been proved that GAC effects as biological activated carbon in adsorbing the toxic/refractory compounds contained in PW therefore simultaneously enhancing the activity of SOB sludge.
Long term continuous treatment (≈400 d) was performed during a range of thiosulfate (S₂O₃^2-) load and the hydraulic retention time (HRT) fixed as 0.8-3.7 kg-S₂O₃^2-/1/d and 7.7-1.9 d, respectively. The results demonstrated that the treatment effectiveness trends to worsen every period of 3 or 4 months, i. e., reactor pH, the dissolved organic carbon (DOC) and S₂O₃^2-in the effluent increased gradually, while formation rates of sulfate (SO₄^2-) decreased to about 50%. During the 400 days treatment, three cases of worse trends were observed, and were then recovered by just renewing the GAC in the reactor. This suggests that absorption of GAC progressed in parallel with its regeneration, and then reached its saturation point while its further regeneration ability lost. Thus, to further clarify the adsorption capacity of the spent GAC, its equilibrium and comparison experi-ments with new GAC were examined, which confirmed that the spent GAC has been reaching breakthrough situation with no further adsorption capacity.

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This study is an attempt to burn Pulverized Refuse-Derived Fuel (P-RDF) prepared from municipal solid waste (MSW) for recycling of waste resources. New experimental apparatus and method were established in order to obtain fundamental data of P-RDF combustion in a furnace. A small amount of P-RDF in the fuel holder were heated up by high temperature flow gas under a variety of O₂concentrations. The pyrolytic and burnt gases were extracted by a water-cooled sampling probe, and then these compositions were analyzed by a FT-IR gas analyzer. The effects of temperature and O₂concentration on the composition in flue gas were investigated in order to elucidate pyrolytic or combustion mechanisms of P-RDF. Results showed that the pyrolytic and burnt gases include components such as nitrogen oxide, carbon monoxide, carbon dioxide, methane, ethylene, ethane and propylene, and the main component of the pyrolytic hydrocarbonic gas is methane. The concentrations of the pyrolytic and burnt gases mentioned above were raised with an increase in temperature and O₂concentration in flow gas. In particular, fuel NO was observed even in the low temperature of 400°C in N₂gas flow.

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In our previous experiments four simulated landfill column reactors were operated for 700 days under sulfidogenic and methanogenic conditions to study the methane gas emission trends during the degradation of model solid waste. Results from the simulated landfill column reactors provided only a general trend and nature of degradation of the model solid waste loaded in the reactors. Explicit results regarding the efficiency of the different rectors to degrade the model solid waste could not be inferred. Thus to understand the degradation of cellulose (a major component of model solid waste) under sulfidogenic and methanogenic conditions vial batch experiments were carried out and the results are presented. The leachate from either reactor R1 (partially saturated methanogenic reactor) or reactor R3 (fully saturated sulfidogenic reactor) was used to inoculate the vials.
According to the results of vial batch experiments, the degradation of cellulose was faster under sulfidogenic condition than methanogenic conditions. Acetate accumulated during the sulfate reduction of cellulose under sulfidogenic conditions. The electron flow under sulfidogenic conditions was dominated by sulfate reducing bacteria. Finally, methane gas was effectively suppressed under sulfidogenic conditions.

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For the first time a“Recycle Market”was held at Hiroshima-University for new students and alumni. The purpose of this study is to begin“Hiroshima-University 1997 Recycle Market”, to clarify legal, financial, personnel and environmental problems and to clear them. The“Recycle Market”was held between February and April, 1997, and legal, financial, personnel and environmental problems were overcome. Another object is to let universities all over Japan begin and establish“Recycle Markets”by publishing the data of this study.

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Fermentation stillage (moisture 92.7wt%, SS 2.45wt%, TOC 37, 186mg/l, pH3.1) of the traditional liquor SHOCHU was treated by low-temperature catalytic gasification using a metal nickel catalyst at 350°C and 19.3 MPa. The treated water had no color, its TOC was 337mg/l and pH7.1. The TOC removal reached to higher than 99%, and CH₄and H₂ rich fuel gas was produced. Nitrogen in the stillage was almost converted into NH₄, dissolved in the treated water. The estimation of chemical equilibrium suggests that nitrogen can be nitrogen gas (N₂), not NH₃, at the reaction conditions.

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