Journal of the Japan Society of Material Cycles and Waste Management
Online ISSN : 1883-5899
Print ISSN : 1883-5856
ISSN-L : 1883-5856
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  • —Case Study on Televisions with Transition to Digital Broadcasting—
    Kazuaki Takahashi, Yasuhiro Hirai, Shin-ichi Sakai
    2021 Volume 32 Pages 1-10
    Published: 2021
    Released: March 06, 2021
    JOURNALS FREE ACCESS
    In order to understand trends surrounding the use and disposal of televisions in Japan, we have analyzed the impact of a major shift from CRT TVs to flat-screen TVs taking into consideration digitalization of TV broadcasting. Two models were compared: the lifespan distributions for CRT and flat-screen TVs were the same in the first model and lifespan distribution differed by type in the other model. Compared to the former model, results showed that the latter model better reflects recent trends with regard to units being used. In the latter model, as calculated under Weibull distribution, the average lifespans from shipment to disposal differ between CRT TVs at 12.8 years and flat-screen TVs at 15.1 years. Based on the fact that flat-screen TVs, which have become widespread in recent years, have a longer lifespan than CRT TVs, it may indicate that the overall lifespan of TVs has increased with this shift.
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  • Nobusuke Kobayashi, Yuma Tachibana, Kenji Kamiya, Yoshinori Itaya, Aki ...
    2021 Volume 32 Pages 11-19
    Published: 2021
    Released: March 06, 2021
    JOURNALS FREE ACCESS
    In this study, a drying experiment was conducted on inorganic sludge with a resin-based drying accelerator in order to clarify the effect of resin emulsion addition on drying behavior. In the experiment, 0.8wt% of acrylic resin emulsion was added to inorganic sludge, and the effect of its addition on drying and the effects of drying conditions such as drying temperature and sludge size on the drying rate were evaluated. Although the drying acceleration effect of sludge differs depending on the drying accelerator type, it was possible to accelerate inorganic sludge drying by adding a small amount of resin emulsion. In particular, the addition of acrylic resin emulsion (DA10) showed a high drying acceleration effect in the large spherical sample with a small specific surface area, since DA10 suppresses the decrease of the water transfer rate inside the sludge. On the other hand, the addition of the drying accelerator to the sludge suppresses the evaporation rate of water on the surface of the sludge, so that it was necessary to optimize the drying temperature and the sludge sample shape when adding the resin emulsion to inorganic sludge.
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  • Junichiro Koshiba, Yasuhiro Hirai, Shin-ichi Sakai
    2021 Volume 32 Pages 20-30
    Published: 2021
    Released: March 11, 2021
    JOURNALS FREE ACCESS
    In this research, the emission reduction effects of PCB countermeasures in Japan were estimated. It was estimated that the cumulative emission reduction of waste storage from 1950 to 2050 was 65.9tons and the cumulative emission reduction by waste destruction was 65.6tons. Additional waste treatment was estimated to have 3 to 23tons emission reduction. Waste decomposition, which reduces PCB stock, reduces not only immediate emissions but also future emission risks. On the other hand, there are some possibilities that waste storage cannot reduce long-term emissions because PCB stock is kept. Moreover, it was suggested that there are some risks that future emissions would increase in the case of long-term waste storage. It was estimated that the increased rate of PCB waste loss would cause approximately 60 to 110tons increase in cumulative emissions. In conclusion, it was suggested that PCB waste storage has a temporary emission reduction effect, but it is essential to destroy PCB waste in order to reduce future emission risks.
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  • —A Case Study on Japan’s Heavy Flooding Disaster of July 2018—
    Ryo Tajima, Junko Morishima
    2021 Volume 32 Pages 31-42
    Published: 2021
    Released: March 13, 2021
    JOURNALS FREE ACCESS
    This study aims to clarify factors that lead people to dispose of disaster waste from cleanup activities after homes were damaged (hereafter termed cleanup waste) at places other than designated temporary storage sites (TSS). Even when local government policy basically advises these wastes to be disposed of at TSS, they are found being discarded at curbsides and other open spaces. We studied actual disposal behaviors and potential determinants of Kurashiki City disaster victims following the flooding disaster of July 2018. The results of a questionnaire survey and its statistical analysis suggest that citizens tend to dispose of cleanup waste at places other than TSS. This happens for several reasons: the TSS is too far away; access to vehicles for transportation is scarce; public information on where to dispose of cleanup waste is not properly understood. Based on these results, we present recommendations for preparedness action, such as identifying open lands that can be modified as TSS in disaster-prone areas.
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  • Jia Xing Liu, Mikiji Shigematsu, Kazuo Tameda, Jia Jiang Han, Sotaro H ...
    2021 Volume 32 Pages 43-50
    Published: 2021
    Released: March 24, 2021
    JOURNALS FREE ACCESS
    The number of leachate treatment facilities with desalination treatment is increasing. When desalination is performed, concentrated solution and dried salt (byproduct salt), which is obtained by evaporating and solidifying the concentrated solution, are produced together with the desalinated water. In recent years, some byproduct salt has been recycled as antifreeze agents, and some has been used as disinfectants at terminal treatment plants by generating NaClO through electrolysis. However, there are many areas that do not use antifreeze agents and nearby areas that do not use disinfectants. Using bipolar electrodialysis (BPED) as one of the recycling methods, a development study was conducted assuming that acids and alkalis are generated and used as a neutralizing agent. Currently, BPED is used in the food and medical fields as a method for producing organic acids and alkalis from organic salts and acids and alkalis from inorganic salts. In this study, we conducted a basic study with different generation sources (leachates from general waste and industrial waste) and different discharge types (concentrated solution and dried salt) of byproduct salt. As a result, HCl with a concentration of 2.82mol/L to 4.23mol/L and NaOH with a concentration of 1.43mol/L to 3.04mol/L were produced.
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