Capping using Geosynthetics has been developed recently to keep as much rainwater as possible from infiltrating into the waste layer and thereby reducing the capping layer thickness. To evaluate the restraining effects of rainwater infiltration within the landfill sites’ capping layer using Geosynthetics, sprinkling experiments using two soil apparatuses resembling an actual capping layer were performed in this study. Infiltration and drainage amounts were measured. To elucidate the action of water within the capping layer with the Geosynthetics, a water flow model was designed based on experiment results. The drainage layer shape and construction conditions influencing the rainwater infiltration were simulated using the model. Results showed that drainage and infiltration rates were about 90% and 10%, respectively. Consequently, capping with Geosynthetics can restrain much rainwater from infiltrating into the waste layer. Results obtained using the model also revealed that construction length strongly influences drainage and the infiltration rate.

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There are not many municipalities that have applied social systems to deal with the recycling of garbage generated in homes. One of the reasons for this is that local inhabitants do not always willingly participate. The level of inhabitant participation depends on factors such as the system type of recycling, urbanization, and housing conditions. Almost all LCA studies compare recycling systems with the condition that 100% of the household waste is being recycled, or on a basic unit of garbage. However the results of one LCA will be different from that of another when there is actually a 100% waste recycling rate, if less inhabitants take part in garbage collection or if the extent of promoting recycling facilities to local households is low. This LCA study, therefore, takes into account housing conditions, the extent of participation in waste collection by inhabitants, and the extent to which recycling facilities are being promoted to local households. Results showed that differences in participation by inhabitants makes a difference to the overall LCA evaluation when it comes to waste recycling systems. It is necessary for municipalities to conduct their own environmental impact evaluations for each system, taking into account the practical extent of participation by inhabitants.

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This study estimates expense cutbacks for final disposal and the potential restoration costs associated with the categorization of inert waste landfills (IWLs), where only inert industrial waste is being disposed of. The expense for final disposal has been reduced, as inert waste is disposed of in IWLs at a lower price than that of other wastes disposed of in sanitary landfills (SLs). The total reduction amount has been calculated from the volume of inert waste being disposed of and the disposal fees for IWLs and SLs. The reduced expense is estimated to be 4303 billion yen for the period 1977-2003. The potential restoration cost is considered to be a virtual restoration cost required if the cases of inappropriate disposal at IWLs were to be restored. Information on cases of inappropriate disposal has been collected from various data sources. The potential restoration cost was estimated to be 537 billion yen or 1072 billion yen. We compared the estimated figures and found that the net reduction was 3231 billion yen or 3766 billion yen. Although significant expenses were reduced, it should be noted that a considerable amount of restoration cost would also be generated.

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The behaviors of chlorine in municipal solid waste incinerator residues in the process from incineration to disposal in a landfill site were studied. Before landfill disposal, fly ash contained a larger amount of chlorine, however the ratio of the chlorine as an insoluble chlorine compound was larger in bottom ash. Friedel’s salt, an insoluble chlorine compound was found in both fly ash and bottom ash, and it was confirmed that the compound was formed in the hydration process before landfill disposal. In a landfill site, pH was decreased by the infiltration of rainwater that decomposed insoluble chlorine compounds and washed out soluble chlorines especially in shallow portions. A series of experiments on artificial hydration of dry bottom ash before landfill disposal were also performed to clarify the origin of insoluble chlorine compounds. The results of the experiments showed that the hydration and chlorination of calcium compounds to form insoluble chlorine compounds occurred in a day.

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A questionnaire survey was conducted of farmers in Hokkaido who had installed automatic-turning composting facilities (composting facilities) or biogasification facilities for treating cattle excreta. The purpose of this survey was to investigate the characteristics of the farmers and the advantages and disadvantages of these facilities, as well as to clarify the effects of their installation for the farmers.
Most of the farmers who installed composting or biogasification facilities had large farms feeding about twice as many cattle as the average in Hokkaido. Their motivations for installing these facilities were determined to be, first, the need to solve cattle excreta management problems and, second, the existence of financial support for installing such facilities.
Many farmers answered that the advantages of installing composting or biogasification facilities were that they could produce solid or liquid manure that was of high quality and low odor, and that the processing of cattle excreta in these facilities was stable even in areas with cold winters. They also said that the high construction and maintenance costs of the systems and the labor required for their operation were disadvantages. The construction and maintenance costs of the biogasification facilities were less than those of the composting facilities. There was only a small difference in the increased labor time required for management of cattle excreta between composting and biogas-ification facilities. The average increase in time for both types of facility was about 20%, although about twice as many cattle farmers who had installed biogasification facilities said that the process was laborious, compared with those who had installed composting facilities. The reason for this was assumed to be that farmers found the maintenance of the biogasification facilities more troublesome because they have many parts that need to be maintained and some repairs require experts.

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The silicon content in livestock manure compost was investigated and a simple estimation method was developed. A total of 87 compost samples, including 77 cattle manure compost (CMC) samples, 6 swine manure compost (SMC) samples and 4 poultry manure compost (PMC) samples were used. These were produced by farmers or compost production companies in Yamagata Prefecture. The results were as follows.
1) The silicon content of CMC ranged from 12.1 to 307.8g kg⁻¹ dry weight (DW) with an average of 95.4g kg⁻¹ DW. The silicon content of SMC was between 9.5 and 79.6g kg⁻¹ DW with an average of 34.1g kg⁻¹ DW. For PMC, it was between 2.4 and 36.1g kg⁻¹ DW with an average of 16.8g kg⁻¹ DW.
2) A significant negative correlation was obtained between carbon (x) and silicon (y) contents in CMC: (y = −0.75x + 354, r = −0.904). A significant positive correlation was obtained between ash (x) and silicon (y) contents in CMC: (y = 0.44x−39.8, r = 0.970). Therefore, silicon content in CMC can be estimated from carbon or ash content.

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The question of whether or not the new recycling system, based on Japan’s Automobile Recycling Law, will encourage development of easy-to-recycle vehicles has recently been raised. The authors, therefore investigated “recycling-friendly designs” for automobiles as practiced by automakers, and examined the relationship between recycling-friendly designs and recycling costs for automobile shredder residue (ASR).
The research concluded that it is unlikely that the development of easy-to-recycle vehicles will lead to a reduction in ASR recycling costs at present. The primary reason for this is that since automakers are only partially involved in the new automotive recycling system, recycling operators (such as dismantlers) are not fully stimulated to take advantage of recycling-friendly designs, especially those that promote reuse. The authors suggest that it will be important to create a “recycled parts and materials market” in order to gain the full benefit of recycling-friendly designs.

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