So as not to pose any adverse environmental impact, landfill requires long-term management until the waste is considered stabilized. Consequently, maintenance costs increase as the period of time needed to manage the landfill lengthens. As the landfill stage is situated at the end of the waste management process, the performance of a landfill is influenced by all other waste management options. In order to shorten the landfill-care period, therefore, all waste treatment processes including source separation methods, should be considered pre-treatment steps leading up to landfilling. Key factors of waste stabilization are organic content of waste as well as the moisture and oxygen levels in the landfill. Construction and operation of the landfill should be appropriately selected based on characteristics of the specific waste.

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As the world began to consciously take up the notion of developing sound material-cycle societies since the late 1990s, the concept of the sustainable landfill has been discussed. It has been made clear that landfills that are an end-of-pipe waste management technology cannot achieve landfill sustainability. We have therefore turned our attention upstream in the waste flow, before landfilling, in order to gain better control over the quality and use of waste materials. We propose three types of landfilld corresponding to the quality and use of wastes : (1) stockpiling-type landfill, (2) reclamation-type landfill, and (3) enhanced bio-stabilization-type landfill.

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In order to appropriately operate and maintain any landfill facility, while also conserving the surrounding environment and protecting the health and safety of residents living nearby, it is important to fully understand all of the facility components and their functions. In order to uphold this, the National Federation of Industrial Waste Management Association (NFIWMA), which is comprised of Industrial Waste Management Companies, has organized various working groups to address all issues associated with waste management ; investigating and solving waste management issues such as collection and transportation, incineration and landfill. The groups collected a range of information on the quality and quantity of industrial waste, examples of accidents and their countermeasures, and other pertinent data, and collated them to publish the Manual of Landfill Operation and Maintenance Management for Industrial Waste in 2006 as the outcome of their work. Furthermore, NFIWMA has been made significant efforts to upgrade the technical skills in the field of SWM and to achieve safe and appropriate management, such endeavors can be seen in the regular conducting of sectional meetings and skill-upgradation training workshops on landfill operation and maintenance for all members who are using this manual. The above-mentioned activities have been summarized in this paper.

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Although emissions of municipal solid waste are decreasing year by year, it is difficult to construct new landfills due to the fact that permission from stakeholders is hard to obtain. The high amount of municipal solid waste from Saitama Prefecture is actually disposed of in another prefecture. Incinerated ash had been the main product being disposed of at landfills, but its recycling rate has currently increased due to technologies being employed by cement companies.
On the other hand, the recycling rate of crushed residues, another major project being disposed at landfills, has not progressed. Under the current conditions, in order to reduce landfill waste, it will be necessary to investigate and study the current status of the incombustible trash processing system.

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The Stockpile Landfill is a recently proposed waste management facility that aims to stock landfilled wastes with values that are currently low in order to later recycle them at higher values determined by the market and/or technical developments.
This paper focuses on four categories of stockpiled wastes : electronic substrate, shredder residue, incineration ash and plastic. Potential amounts and resource values are estimated for each category. Although electronic substrate already has a significant value, incinerated ash and shredder residue are estimated to be able to obtain a higher value if the value of metals rises by about 3 to 5 times. Our feasibility study on the Stockpile Landfill implies a new landfill business model. We believe that, due to Japan′s scarcity of natural resources, construction of a comprehensive system for the securing of resources, including a perspective on stockpiling, is imperative.

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This article addresses the feasibility of a new landfill category known as reclamation type landfill, which uses inert waste materials. After reviewing previous research, waste materials and by-products appropriate for this category were selected in terms of their geotechnical properties. Environmental and economical feasibilities were analyzed by optimizing the waste management strategy under a specific scenario, taking into consideration environmental costs from CO₂ emissions, land conversion and so on. Although some technical and institutional issues still remain, results indicate that this new landfill category could be realized economically by considering indirect environmental costs. In addition, the basic concept of environmental suitability assessment for reclaimed waste-based materials was discussed, For this, we referenced relevant technical guidelines and manuals in which environmental risk-based approaches specific to site conditions and material properties were employed for reused/recycled materials in geotechnical applications.

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Coastal final disposal sites are planned and constructed for two purposes : the proper disposal of wastes and, once disposal is fully completed, utilization of sites vacant properties for port and/or urban development projects. There are, however, some discriminative characteristics associated with coastal final disposal sites. For example, in comparison to inland landfills, stabilization of the disposed waste takes longer at coastal sites and it is also necessary to manage and control the residual water levels in the allowable range, etc. Due to problems such as these, research and development on these technologies, for more effective utilization of the sites, must be implemented.
From this point of view, our work has categorized the acceptance criteria for operating coastal final disposal sites, evaluated the geotechnical characteristics of the waste landfill layer and evaluated the effects of improving the strength of the soil layer using a mixture of iron slag (a co-product of the iron industry).

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The impact of natural weathering on the behavior of Fe-rich phases, their transformation, and the formation of the relevant secondary products in the weathered bottom ash samples of a municipal solid waste incineration (mono) landfill site in the northeast USA were systematically investigated. Samples of various ages (1-20 yrs) were collected from four locations of the landfill in 2009. Optical microscopy, SEM-EDX, XRD and XRF examinations were applied in order to document the footprints of weathering processes. Use of these techniques revealed that several secondary products (amorphous or crystalline) have been developed, including goethite (α-FeOOH), lepidocrocite (γ-FeOOH), hematite (Fe₂O₃), magnetite (Fe₃O₄), iron oxide (FeO), and Fe-rich Ca-Si and Ca-Al-Si gel phases. They occurred under variable environmental conditions as the weathering products of primary iron-bearing phases that usually exist in incineration ash. The strong affinity of these secondary phases with heavy metals of environmental significance such as Zn, Cu, Pb, and Ni was also identified. This suggests that the development of secondary Fe-rich products can partially contribute to the reduction of heavy metals released into the surrounding environments.

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