Recently, increase of societal concern in home appliance recycling
system has been the international trend. In Japan, model business projects and social
pilot programs have been conducted in various areas and study groups of
well-informed people have been organized for its study. In April 2013, “Law to
promote use of used home appliance including electronic devices as resource
again”, so called “home appliance recycling law” was enforced. In this paper, the results
of the experiment are outlined and the current status related to the new policy
and future problems are analyzed.

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Based on the results of the experiment where a RCP and an extruder were connected, we confirmed the continuous operability and backflow prevention effect by connecting to a catalytic cracking liquefaction system. As a result of an evaluation intended for containers and packaging plastics waste, the pay time was estimated to be 1.8 years.

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It is expected for carbon fiber reinforced plastic (CFRP) to be used as the composite materials of automobiles and aircrafts to significantly reduce the transportation energy. The objective of this research is to optimize the two staged thermal treatment system consisting of a carbonizing furnace thermally to decompose the plastic components in the CFRP and a oxidizing furnace to burn the residual carbon on the carbonized carbon fibers. As the results, it was confirmed for the carbonizing furnace that the heat capacity of the product gases and tar after thermally decomposed the resin components can cover the amount of heat required to the CFRP pyrolysis and that the superheated steam can give energy saving of 63% for a small furnace CYT-1700 and of 56% for a large furnace CYT-7000.  For the oxidizing furnace, the oxidizing condition less than 500 C is appropriate and it can achieve the energy saving of 33%, which can further improve to 48% in stable operation condition.  In the research of the carbon fiber strength tests, it was confirmed that the recycled carbon fiber could obtain more than 80% strength of the virgin carbon fiber.

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In order to know a mechanism of hydrogen sulfide gas production at ground improvement using recycled gypsum board, we evaluated an influence of sugar content distribution in the waste gypsum board. We observed that the sugar content distribution in the waste gypsum board which came from deconstruction work is consistent with that of new gypsum board, and the sugar content at a center of the waste gypsum board is lower than that at edges of it. The hydrogen sulfide gas production rate depends on the sugar content.

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Development of safety recycle system for waste gypsum board

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Steelmaking slag is a byproduct of steel industries and produced. Course or granule sizes of the particles are almost the same size of natural sand in sandy beach. Therefore, the steel slag is expected to be used as an alternative material of marine sand for the creation of coastal ecosystems such as tidal flat and eelgrass bed. However, steelmaking slag has hydraulic property caused by the release of CaO and the solidification of steelmaking slag in sediment might have negative impacts on habitat for benthos and eelgrass. Therefore, the purposes of this study are to investigate solidification behavior of steelmaking slag in marine environment and monitor migrated aquatic organisms. In this study, dredged soil was mixed together with steelmaking slags ton alleviate significant pH increase and solidification. The drainage soil was mixed with decarbonized and dephosphorized slag at the ratio of 8 wet w/w% and submerged in sand filtrated seawater. The changes in Vane shear stress was monitored. The solidification were suppressed by adding the drainage soils. 

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It is necessary to predict the long-term leaching
amount of chemicals from the byproduct/recycled materials such as steel slag, waste
concrete, and so on for their effective utilization and safety evaluation because
the chemicals included in them are dissolved with rainfall and diffused in soil
and groundwater and therefore they have a potential to contaminate the
surrounding environment. The serial batch leaching test and the column leaching
test are standard methods widely used for evaluating the long-term leaching
amount of chemicals in the byproduct/recycled materials. However, the
compatibility of both tests has not been clarified so that the chemical
leaching behavior in actual sites where the byproduct/recycled materials are
used is not necessarily controlled to prevent the environmental contamination. In
this study, the column leaching tests for the byproduct/recycled materials were
conducted in the same conditions as fluid velocity, liquid-solid ratio, and solvent
exchange program of the serial batch leaching tests to investigate whether chemical
leaching behavior in actual sites can be predicted from the serial batch
leaching tests or not.

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A recycling technology of by-product salt from waste treatment processes such as incinerator, melting furnace and leachate etc., is presented. To produce eco-NaClOfrom the by-product salt by means of electrolysis without separation membrane is excuted at the condition of salt solution concentration of 5% and produced eco-NaClO of 0.3%. We propose a program to use the eco-NaClO made from leachate of the landfill for sterilization of the treated discharge water from the sewage plant in the same city. A feasibility study is conducted on four cases of the program changing the size of cities. The FS works show the program gives not only good environmental preservation, but also economical benefit to the municipalities having more than 100,000 people.

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Poly butylene succinate-co-adipate(PBSA) is one of the biodegradable plastics. The waste bag made by PBSA is sold on open market. However, the degradation of the special bag is difficult in composting device. This research presented the effect of return compost inoculation on the PBSA degradation in compost. The results revealed that return compost inoculation could accelerate the PBSA degradation in compost. In addition, return compost inoculation was more effective than inoculation of pure cultivated PBSA degrading bacteria (Acinetobacter sp.Strain S49). In conclusion, it was found that PBSA degradation can accelerate by not only inoculation of PBSA degrading bacteria but also return compost inoculation that is simple operation and low-cost.

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Municipal Solid Waste Management (MSWM) is considered to be one of the serious environmental issues
confronting local governments (LGs) in Asian developing countries. Biodegradable waste makes up a large proportion of the MSW stream (50-70%) and final disposal in open landfills posing a serious health
risk and releases a large amount of greenhouse gases (GHGs). As a result, there
is widespread interest on the part of LGs for diverting organic
waste into composting to extend the life of landfills, create economic and
environmental benefits, and ultimately reducing the pressure on managing the
ever increasing complexity of MSW. However, composting is seldom integrated
into the MSWM systems as a strategic element and there is very little evidence
available of its financial analysis. This paper therefore aims to discuss the
key composting methods, its operation and management systems and financial
viability, reviewing the experiences of composting schemes in six Asian
countries. The study identified that the
success of composting programmes largely depends on its economic viability.
Composting revenues alone is not enough to cover both investment and O&M
costs of the composting plants. The supportive policies and regulations are
required to ensure the substitute revenues and sustainability of the
composting.  

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