Time filter

Source Type

Ōsaka, Japan

Yamamoto T.,Hiroshima University | Kondo S.,Hiroshima University | Kim K.-H.,Hiroshima University | Asaoka S.,Hiroshima University | And 4 more authors.
Marine Pollution Bulletin | Year: 2012

In order to prove that hot air-dried crushed oyster shells (HACOS) are effective in reducing hydrogen sulfide in muddy tidal flat sediments and increasing the biomass, field experiments were carried out. The concentration of hydrogen sulfide in the interstitial water, which was 16mgSL-1 before the application of HACOS, decreased sharply and maintained almost zero in the experimental sites (HACOS application sites) for one year, whereas it was remained at ca. 5mgSL-1 in the control sites. The number of macrobenthos individuals increased to 2-4.5 times higher than that in the control site. Using a simple numerical model, the effective periods for suppression of hydrogen sulfide were estimated to be 3.2-7.6 and 6.4-15.2years for the experimental sites with 4 and 8tons per 10×10×0.2m area, respectively. From these results, it is concluded that HACOS is an effective material to remediate muddy tidal flats. © 2012 Elsevier Ltd. Source

Asakura H.,Fukken Co. | Matsuto T.,Hokkaido University | Inoue Y.,Japan National Institute of Environmental Studies
Waste Management and Research | Year: 2010

In Japan, as the construction of new landfill facilities has become extremely difficult and the number of sites procured for landfill construction has decreased due to the not in my back yard (NIMBY) syndrome, it has been assumed that the adoption of new technologies has increased. As the performance of new technologies exceeds that of conventional technologies, it is also assumed that residents would prefer the use of these new technologies and therefore any construction plans should be devised to ensure their use to ensure residents satisfaction. In the present study, the technologies adopted for municipal solid waste landfill facilities constructed in recent years (2000 to 2004) in Japan and the bases for their adoption were investigated by means of a questionnaire survey. One of the main bases for the adoption of new technologies was the request by residents for new technology for roofing, rather than the other for new technologies for barrier systems, leachate treatment, and monitoring. In addition, it is possible that the municipalities did not recognize the difference between conventional and new technologies as defined in this study. The roof-type landfill that isolates waste from the surrounding environment was one of the requirements for the construction of new landfill facilities identified in the present investigation, and in this regard waste isolation should be required in all circumstances. © The Author(s), 2010. Source

Asakura H.,Fukken Co. | Endo K.,Japan National Institute of Environmental Studies | Yamada M.,Japan National Institute of Environmental Studies | Inoue Y.,Japan National Institute of Environmental Studies | And 2 more authors.
Waste Management | Year: 2010

It is known that aeration reduces rapidly the concentration of organic matter in leachate. However, the oxygen flow rate required to attain a certain reaction rate of organic matter should be carefully estimated. In this study, using the oxygen ratio (the ratio of oxygen flow rate by aeration to oxygen consumption rate of waste layer) as a parameter, the reaction rate of organic matter in leachate from landfilled incineration ash and incombustible waste upon aeration was evaluated. Total organic carbon (TOC) in the leachate was reduced rapidly when the oxygen ratio was high. The decomposition rate exceeded the elution rate of TOC in the leachate from the waste layer for several days when the oxygen ratio was above 102. The results indicate that the oxygen ratio can be used as a parameter for the aeration operation in actual landfill sites, to rapidly stabilize organic matter in leachate. © 2010 Elsevier Ltd. Source

Kim K.,Hiroshima University | Hibino T.,Hiroshima University | Yamamoto T.,Hiroshima University | Hayakawa S.,Hiroshima University | And 3 more authors.
Marine Pollution Bulletin | Year: 2014

Field experiments were carried out to evaluate the effect of Granulated Coal Ash (GCA) on remediation of coastal sediments in terms of removing phosphates and hydrogen sulfide. Phosphate concentrations in the sediment were kept below 0.2mg/l after the application of GCA, whereas those in the control sites increased up to 1.0mg/l. The concentration of hydrogen sulfide in the sediment was maintained at almost zero in the experimental sites (GCA application sites) for over one year, whereas it ranged 0.1-2.4mgSL-1 in control sites. Meanwhile, individual number of benthos increased in the experimental sites by several orders of magnitude compared to the control sites. The major process involved in hydrogen sulfide removal by GCA was thought to be the increase in pH, which suppresses hydrogen sulfide formation. From our findings, we concluded that GCA is an effective material for remediating organically enriched coastal sediment. © 2014 Elsevier Ltd. Source

Watanabe S.,Fukken Co. | Hyodo M.,Yamaguchi University
15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015: New Innovations and Sustainability | Year: 2015

A large amount of reclaimed ground along Tokyo bay suffered damage due to liquefaction during the 2011 Great East Japan Earthquake. The liquefied areas were mostly concentrated in newly reclaimed land. The aging effect is considered to be important for the susceptibility of ground to liquefaction. The liquefied soils contained a lot of fines and the fines content varied by place. In this study, in order to understand the dynamic deformation characteristics of the ground, a series of bender element tests and hollow cylindrical torsional tests were performed on sand and clay mixtures with various proportions of fines content. Furthermore, the water content of the mixed clay was varied between the liquid limit and two times the liquid limit. The variation of water content of the clay in the sand-clay mixtures was considered to represent the effect of aging. Test results show that the maximum shear stiffness decreased with increasing fines content and water content of the clay3. Source

Discover hidden collaborations