AK System was developed as a method for recovering resources from municipal solid waste through the utilization of an applied kiln in cement. This paper compares the effects of the AK System on energy consumption, CO₂ emissions, and landfill waste generation using conventional incineration and landfill disposal. Not only the reduction of landfill waste, but also energy consumption can be controlled when the processing of municipal solid waste is changed over to the AK System. CO₂ emissions are also reduced when the change is implemented. CO₂ emissions increased when this effect eased the chlorine tolerance in the cement. This was especially noticeable when cement already containing a high-chlorine content was utilized. Moreover, combustible waste, non-combustible waste, residues of bulky waste and resource waste can also be applied as cement raw materials and fuels through treatment using the AK system. Possibilities for achieving zero landfill from these wastes were also estimated in this study.

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We carried out thermal degradation of acrylonitrile-butadiene-styrene terpolymer (ABS), Nylon 6 (PA) and their mixtures in soybean oil at temperatures from 320°C to 360°C. In the mixtures, the decomposed effluent with low molecular weight increased quite markedly and the apparent activation energies of decomposition were smaller than those of the individual polymers. (ABS Ea= 61.3 kcal/mol, ABS 80/PA 20=41.6 kcal/mol, ABS 50/PA 50=27.3 kcal/mol and PA=86.0 kcal/mol.) The mixture of ABS and PA instantly degraded into oily products and oligomers of the polymers in soybean oil. The oil reacts with the polymers to speed solubility and decomposition.

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This study was conducted to compare the performances of batch and continuous hydrogen fermentation of a mixed substrate (dog food) using a microflora. Hydrogen gas production, substrate decomposition, and metabolic pattern were evaluated for the comparison. The batch reactor was operated at 35°C with a constant pH (ranging from 4.0 to 7.5) and various substrate concentrations (TS 2%, 5% and 10%) . Hydrogen fermentation was greatly affected by pH at each TS concentration and the optimal pHs for obtaining maximum hydrogen yield were identified to be 4.5-5.5 for TS 2%, 5.5 for TS 5% and 6.5 for TS 10%. The maximum hydrogen productions at TS 2 %, TS 5 % and TS 10% ranged from 93.9 to 108 mL/g-VS. The H₂ yield at the optimal pH was as high as 1.80 mol-H₂/ mol-glucose. Butyric acid and acetic acid were the main products at optimal pH, while a complex fermentation pattern was obtained at a pH close to 4.0 or 7.0. In another experiment, the continuous hydrogen fermentation was conducted at 35°C, TS 10%, pH 6.5 and various HRT (from 6.4 to 36.5 hour) . The maximum hydrogen production in the continuous fermentation was as low as 0.21 mol-H₂/mol-glucose, which was obtained at an HRT of 12.8 hours. The experimental results indicate that in treating mixed organic wastes continuous hydrogen fermentation is more difficult than batch fermentation.

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For the purpose of promoting the beneficial use of molten slag obtained from municipal solid waste incineration ash, we investigated the strength of slag and the characteristics of Pb leaching in different ash compositions, identified the range of ash composition suitable for high quality slag, and elucidated the mechanism of Pb leaching from slag.
The molten slag was produced by slowly cooling model incineration ash at a cooling rate of 4°C/ min, the composition of which was adjusted using a reagent. An abrasion test was used to estimate the material strength of the slag. The test results show the formation of Gehlenite crystals by precipitation, low abrasion loss, and high slag strength in the basicity (CaO/SiO₂) range of 1.25 to 1.75. The results of the leaching test conducted in an acidic environment (pH 4.0) indicate that Pb leaching rates for eutectic compositions with basicity range of 1.0 to 1.25 are about 2 to 3 times higher than those for other ash compositions. The Japanese Leaching Test (JLT-46) indicates that most of the ash compositions with a basicity of 1.0 to 2.0 fulfilled the criteria for Pb leaching concentration. We conclude that the adequate ash composition is in the basicity range of 1.5 to 1.75 for high quality slag. Furthermore, the results prove that if the ash composition is the same, the amount of Pb leaching is proportional to the content of Pb in the slag under constant pH conditions.

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We evaluated the aerobic solubilization level and the application of two-phase methane fermentation in a two-phase methane fermentation system that uses an aerobic solubilization process to treat food wastes and garbage. Since the average particle diameter was 86μm, we found that the aerobic solubilization process was the same level as other solubilization methods. By comparing the microbial activities of the aerobic solubilization and acidification effluents in a batch test, we observed that the biogas and methane gas production and the methane gas content of the latter effluent were more than those of the former effluent. When garbage is processed using the aerobic solubilization process, a two-phase methane fermentation is more efficient than a single-phase one. As a result of investigating the microflora using the PCR-DGGE method, the microbes in the aerobic solubilization differed from those in the acidification, and it also became clear that there was co-metabolism between the microbes in each one.

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In order to figure waste density and how much waste should be fed into a furnace, it is important to understand any changes in waste volume. In this study, a system was developed for calculating the volume of waste in a hopper using a stereo image processing technique equipped with a digital camera that has three CCDs for obtaining the surface shape of waste in the hopper. First, accuracy of the distance measurement using the digital camera with three CCDs was achieved to establish a method for automatically collecting data and calculating volume by using a computer and a camera. This system was applied to measure the volume of real waste in a municipal solid waste incinerator. The surface shape and the volume of real waste in the hopper were continuously measured and calculated. The results, using the stereo image processing technique, were in almost perfect agreement with those using a laser distance meter. As a result, it was confirmed that the link-up between the system calculating waste volume using the stereo image processing technique and a waste compaction and feeding model can create an advanced waste feeding system that estimates the volume and weight of waste fed into furnace from the volume and density of waste fed into the hopper.

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This study constructed a thermal recycling system of waste polystyrene based on thermal decomposition. Its application to diesel fuel is discussed. The decomposed PS oil has a low cetane number and shows a long ignition delay. Therefore, its application as an alternative fuel to a conventional diesel engine is difficult. On the other hand, the PS oil characteristics are highly applicable for a homogeneous charge compression ignition (HCCI) system. Experimental investigations using an HCCI system fueled with PS oil showed almost equal thermal efficiency to that of a conventional diesel engine. The NOx emissions were sufficiently low to meet present emission regulations for urban areas without exhaust gas treatment. This fact suggests that the present system is useful as a co-generation system in urban areas.

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The hydrothermal properties of municipal solid waste incinerator bottom ash and leaching characteristics of heavy metals from the treated samples were examined. In addition, the control mechanism of the leaching of Pb was studied using a variety of leaching tests and SEM/XMA.
While having practical bending strength, the samples didn't always satisfy the Japanese Environmental Agency Notification No.46 (LT 46) with regard to Pb.
From the pH dependence of the Pb leachability, the existence of Pb not immobilized by hydrothermal treatment was revealed. Furthermore, by the chelating agent solution/extraction test devised in this study, it was estimated that such non-immobilized Pb comprised more than several % of the content even in the case of the sample that satisfied LT 46. It was also found that both the formation of basic lead carbonate and adsorption were responsible for the decreased leachability of Pb.
Moreover, the formation of a plate-like crystal containing large amounts of Pb was observed by means of SEM/XMA analysis. It was considered that the formation of this crystal is evidence for Pb uptake in the crystal except for tobermorite and might have a relationship to the control mechanism of the leaching of Pb.

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Recently, the areas of food manufacturing and commerce have seen a positive increase in recycling due to the fact that the Food Recycling Law has been adopted as an opportunity. On the other hand, recycling of household garbage has not advanced because this recycling must be applied outside of the law.
This study comprehensively analyzes the struggles undertaken by the Rainbow Plan of Nagai City in Japan's Yamagata Prefecture, which has set a national precedent in formulating future directivity for the recycling of household wastes. The Rainbow Plan's recycling system firstly clarified the formation factor through its material flow analysis. The effects of constructing a recycling system were then evaluated from the environmental, economic, and social viewpoint. Finally, future directivity for a total recycling system of common household garbage was examined.

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During field trials using ash melting furnaces at a commercal plant and test plant, it was observed that a higher rate of mixing of combustibles reduces the lead concentration in molten slag. Rigorous laboratory experimentation was carried out to ascertain the correlation between various parameters such as the rate of mixing of plastics, the rate of mixing of fly ash and the rate of vaporization of heavy metals. The rate of mixing of fly ash has a strong influence on the rate of vaporization of lead and cadmium. Mixed plastics promote vaporization of lead and cadmium from the ash quite significantly when the rate of mixing of fly ash is in the lower range. As one of the most critical regulatory values for the recycling of molten slag, lead content (<150 mg/kg) was measured with method #19 as per the law regarding soil contamination. In this laboratory experimentation, the co-combustion of waste plastics with ash has resulted in a significant reduction of lead concentration in molten slag as per method #19. These facts suggest that the utilization of waste plastics in an ash melting furnace is an effective measure to control the quality of slag for recycling and can be regarded as “chemical recycling of waste plastics”.

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