In recycling systems used up until this point in Japan, only valuable or highly pure resources were recovered, and many low-toxicity substances were left untreated and not consistently handled. This means they were sometimes being just scattered into the environment haphazardly. Because the hazardous potential of these substances has become a source of environmental pollution, it is necessary to maintain adequate recycling systems for each and every product containing toxic substances. It is especially necessary to develop recycling systems for electronic products which often have low-toxicity substances in them.
In this paper, we proposed an analytical method which uses an LCA-base with the consideration of adverse effects from low-toxicity substances. In one case study, low-toxicity substances found in copying machines were examined with regard to the fact that these same substances were liable to become scattered into the environment. The potential strength of harmfulness was then evaluated for environmental loads relating to energy consumption. Our research concluded that recycling of plastic units for outer frames should be given priority over the recycling of units made of steel.

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Intensified humidity-control-charcoals (IHCCs) are produced from wood waste. IHCCs are intensified by two kinds of salt, sodium chloride and calcium chloride. Conventional charcoals have no high humidity control capacity; the absorption of steam into charcoals is particularly limited in the high humidity range (over 60% RH) . IHCCs are free from that limitation.
Absorption of steam into IHCCs occurs in two phases, an adsorption phase and a reserve phase. The absorption phase is the process by which the salts attract steam from the atmosphere. The reserve phase is the process by which the charcoal retains that steam as water. Analyzing and improving IHCCs using this division of processes, the humidity control ability of IHCCs was increased to 1.2-4.0 times that of conventional charcoals. Moreover, IHCCs using calcium chloride have a higher humidity control ability than those using sodium chloride.
Humidity-control materials require durability for their practical application. Silica gel has a higher humidity control ability than charcoals and IHCCs, but the durability of its absorption ability of steam is lower than that of other materials. Considering these characteristics together, IHCCs offer higher humidity control ability than regular charcoal and a higher durability of steam absorption than silica gel.

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An economical process is needed for the treatment of digested liquid to overcome the problems that ammonium nitrogen remains at high concentrations and carbon sources are reduced in the liquid. To develop this process, the author studied a process for the treatment of cattle manure that utilizes in combination the biological nitrification/denitrification process for the removal of nitrogen in wastewater and the two-phase methane fermentation process. This process reduces the amount of wastewater treatment by returning the digested liquid to adjust the concentration of input organic wastes. The author added 1 g/L of nitrate nitrogen to cattle excreta, and confirmed that the nitrate nitrogen was not detected in the liquid in the acid-producing phase. In this instance, dissimilatory nitrate reduction as well as denitrification was observed. The concentration of acetic acid in the input increased from 3.8 g/L to 6.8 g/L after the acid-producing reaction, indicating that the essential acid-producing function was carried out. In the methane fermentation using the liquid in the acidproducing phase, 463 L/kg-VS of biogas was produced, the concentration of methane was 64%, and no adverse effects were observed even when the denitrification function was provided.

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The base-catalyzed decomposition process is superior to the activated carbon absorption process because a secondary waste product is not created when dioxin is broken down. However, some problems remain. Trace constituents in the exhaust gas cause the catalyst to deteriorate, which decreases breakdown performance. Also, there is a possibility that the catalyst may help to form the dioxin.
The authors studied the behavior of precious metal catalysts, which are considered to have a low possibility of dioxin formation, and discovered that the dioxin is composed of the carbon that is included in the catalyst. This carbon adheres while the catalyst is being made. Therefore, this process has been improved so that a catalyst could be made that does not synthesize dioxin.

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The behavior of bromine, antimony and carbon during thermal decomposition process with nitrogen and steam was investigated for fundamental study toward chemical recycling of flame retardant plastics containing brominated flame retardant and trioxide antimony, in nitrogen or steam atmosphere at 573-973 K. Under the current experimental conditions, flammable gases such as methane and ethane were present in pyrolysis gas, and about 60% of bromine and 90% of antimony were transferred to the liquid phase and existed mainly as SbBr₃. However, another portion of bromine in the liquid product was in the form of organic bromide such as 1-bromo ethyl benzene. When the temperature of the system was set at 973 K in a 40% steam atmosphere, debromination of the organic bromide compound was increased in comparison with the decomposition in a nitrogen atmosphere and about 80% of the organic bromide compounds were converted to inorganic compounds of bromine.

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The Yagi Bioecology Center in Kyoto Prefecture treats cow and pig manure and food processing waste by mesophilic and thermophilic methane fermentation. Mesophilic and thermophilic digesters operate in parallel and the organic load of both digesters is about 2.0kg/m³/day. 1.5 years of operation data reveals that the removal rate of organic matter of the two digesters is almost the same. Both digesters produce almost the same biogas volume per unit of organic matter and the biogas content (CH₄, CO₂) is also the same. However, the thermophilic digester has a stronger disinfection effect for enterobacterium than the mesophilic digester. This data shows that digested liquid from the thermophilic digester is better for use as liquid fertilizer than that from the mesophilic digester.

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This study examined how prior voluntary recycling systems affect the social acceptance of a new mandatory recycling/resource separation system. We hypothesized that social acceptance of the new system was based on an outcome evaluation of social benefit and individual cost, as well as fairness evaluations of procedure and distributive justice. A social survey was conducted in Nagoya City to compare residents' evaluations of the system for the area with voluntary recycling and the area without. The respondents in each of the areas were selected by a systematic random sampling. The main results were as follows: 1) Residents in the area with voluntary recycling evaluated the social benefits, individual costs, and procedural fairness of the new mandatory system more positively than those in the area without voluntary recycling; 2) More of the residents with voluntary recycling experience were committed to recycling activities and expected their neighbors' cooperation for the new system, also more of these residents participated in local meetings regarding communication of recycling methods than those without; 3) Those residents who held a commitment to recycling, expected neighbor cooperation, and who participated in recycling meetings had positive evaluation for outcome and fairness. We argued for the importance of volunteer participation, and cooperation between the administration and volunteers, where the introduction of a mandatory resource separation system is concerned.

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Characteristics of mesophilic methane fermentation of cow manure were investigated using a completely-mixed reactor. The experiment was conducted at a temperature of 35°C and a constant influent TS level of 10% at hydraulic retention times (HRT) from 7.5 days to 30 days. The substrate was fed 2 to 8 times a day using a timer-controlled pump. The removal efficiencies of total COD_Cr were in the range of 25-45%, and 1 kg of influent TS produced 0.18-0.32m³ of digestion gas and 0.11-0.20m³ of methane gas. The first-order reaction was found suitable for describing the degradation rate of the organic matter in terms of VS, COD and carbohydrates.

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