The composting rate of coffee grounds was determined by measuring the CO₂ evolution rate and the conversion of carbon with the use of a bench-scaled autothermal composting reactor. The C/N ratio of the coffee grounds was 24.2, thus existing around the optimum C/N range for composting known hitherto. It was quantitatively confirmed, however, that the degradation of organic materials during composting proceeded only at a low rate when the coffee grounds were employed alone since the coffee grounds contained water-soluble nitrogen compounds in only an extremely low amount (1.73×10^-3g/g-dry coffee grounds), lower than 10% of total nitrogen in the coffee grounds. Watersoluble nitrogen-containing compounds (ammonium sulfate and peptone) were added to the coffee grounds to accelerate the composting. In the case of each additive, the decomposition of the coffee grounds was accelerated, and peptone (i.e., an organic nitrogen-containing compound) was superior to ammonium sulfate, the result being accelerated composting. In addition, it was clarified that the growth of thermophilic bacteria, which largely contributed to the composting at high temperatures, was also promoted when composting was accelerated by adding a nitrogen-containing compound.
Furthermore, using waste shellfish obtained from drainage canals in a thermal power plant as nitrogen-containing compounds for composting coffee grounds was also attempted. As a result, it was confirmed that these shellfish were effective in elevating the composting rate of coffee grounds, shortening the composting period to 32 days.

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Boiler tube thinning at up to about 30 cm top of caster-equipped edge of combustion chamber in a refuse incinerator, where exhaust gas recirculating operations were employed for about five years, was especially large and lots of cracks were found in the scale. CaSO₄, NaCl, KCl, etc. were identified in the ash which adhered to the boiler tube and Fe₂O₃, KPb₂ Cl₅, K₂ZnCl₄, NaCl, Na₃Pb₂ (SO₄) ₃Cl, etc. were identified in the scale. There is a possibility that these chlorides and sulfates are related to high temperature corrosion of the boiler tube.
A survey on the high temperature corrosion environment, including gas tempera ture and concentration of gas components according to the location of the combustion chamber in the refuse incinerator, was undertaken under four operating conditions of the air blow rate (O₂ 6.2-10.2% at chimney) . The results show that operation of O₂ concentration of about 10% makes high temperature corrosion environment mild, but low air ratio operation of O₂ concentration of about 6 % makes vaporization of salts increase owing to the rise of gas temperature near the stoker. There is a high concentration of CO, H₂, H₂S, etc. owing to long frame of fire and thus the high temperature corrosion environment of the combustion chamber boiler tube becomes considerably severe.

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Accurate information on the quantity of waste is crucially important for waste management planning and operation.This study investigates how the quantity of household wastes varies depending on municipal government-mandated source separation categories.
Two hundred cities in Japan were surveyed by questionaire. In spite of similar general classification systems for wastes (combustible, noncombustible and bulky) and recyclable materials, the quantity of household wastes differred significantly.
By further investigation of the cities which had a notable difference in quantities of the wastes produced, two types of factors were determined: First, depending on the city the items included in the general waste separation categories varied. Second, the reduction of waste through recycling, disposal of kitchen waste by composting and by incineration at source reduced waste quantities.
Two estimation models were made using the above factors and based on the statistical value and composition of household wastes. The level of accuracy in the models' were satisfactory and the reasons of error were explainable.

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The plasma melting process for municipal solid waste incineration ash has been demonstrated. A melting process transforms MSW incineration ash into something which is harmless and reduces the ash volume. Therefore, various melting processes have so far been suggested for effective ash treatment prior to its dumping on landfill sites. The purpose of this program is to research the characteristics of ash melting using thermal plasma as the energy source. One of the advantages of the plasma melting process is high heat efficiency, since the plasma gas temperature is extremely high. Fly ash and bottom ash emitted from the fluidized bed and stoker incinerator were tested and the melting performances were compared. The NOx reduction method using town gas has also been developed. Thermogravimetry analysis was conducted for each sample to estimate the behavior of ash components under high temperature. The results of the analysis were closely related to the value of the slag capture ratio. The experimental results indicate that the heat efficiency of the plasma process is over 50%. This efficiency is higher than that of the conventional combustion method. NOx concentration in flue gas is less than 150 ppm, and the NOx reduction ratio is over 90%

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Home composting of kitchen refuse at each household has been gathering attention in recent years. A large number of municipalities, which suffer from waste problems, have been practicing a home composting subsidizing program.
The situation of this program was investigated by a questionnaire survey. The results showed that approximately 80% of municipalities have adopted it. Although this program would be effective to waste reduction, it was estimated its duration period has been too short to achieve effective waste reduction so far. A back-up service for home composting device users would be necessary to keep the device being used for a long time and to get effective waste reduction.

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Dioxins generated during the incineration of municipal solid waste are synthesized from organic compounds remaining in the combustion process, chlorine and oxygen. Complete combustion of the waste in the incinerator is therefore the primary requisite for preventing dioxin emission. To this end, it is essential to optimize the furnace design and a combustion method which will allow promotion of combustion, particularly for difficult-to-burn solid organic matter (such as char) .
In order to control the generation of dioxins in municipal solid waste incinerators we conducted basic combustion experiments using small incinerator models of various designs, and selected the swirl-type chamber appropriate for complete combustion. Furthermore, we set up a 20 T/D swirl combustion-type fluidized bed incinerator to carry out the demonstration experi-ment. This revealed that complete combustion could be done as expected and dioxins were also reduced to 0.1 ng/Nm³.
For increasing nitrogen oxides (NOx) with complete combustion, we tried a noncatalytic denitrification test using urea solution to find that a remarkable reduction of NOx as well as dioxins could be realized.

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