The Paris Agreement was adopted as the international framework against global warming, and the global movement to reduce greenhouse gas emissions is progressing. On the other hand, the final disposal amount will be reduced to 13 million tons in 2025 with considering the situation of waste disposal in Japan. Concrete, which is a typical recycled civil engineering material, is a very useful material for drastically reducing waste, while its constituent material, cement, emits a large amount of CO2 in its manufacturing process. Additionally, due to the Japanese eating habits, a large amount of fishery waste including fish residues and shellfish are discharged. Although these are recycled, only about 30% of them are recycled. In this study, because the hydroxyapatite can contribute to reduction of the amount of cement and the plant growth promoted by phosphorus content, the hydroxyapatite produced from fish bones (Fishbone Powder: FbP), which is a fishery waste, is adopted as an alternative material to cement of planting base porous concrete. In addition, from the viewpoints of various physical properties (porosity, permeability and compressive strength), plant growth conditions and CO2 emission reduction, the potential of recycling FbP as a binder for planting base porous concrete is also examined. As the result, CO2 emission of about 2.6 kg per 1 m 3 of porous concrete can be reduced by using FbP as a binder for planting base porous concrete. Additionally, the plant growth ability is also improved while the compressive strength is maintained above 10 N/mm 2 .
9 years have passed since a large amount of radioactive materials were diffused by the nuclear accident at the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company. The decontamination works have almost been completed, and some of the contaminated soil whose topsoil was stripped and collected was transported to the intermediate storage and incineration facilities. However, the contaminated soil containing the radioactive cesium stored in the temporary storage place has not decreased significantly. Additionally, the transportation of the intermediate storage and incineration facilities have an agenda from the viewpoint of cost. Therefore, it is needed to investigate the method of decontamination by which the radiation dose of contaminated soil can be reduced below 8000 Bq/kg at the temporary storage place. Considering the decontamination in the actual temporary storage place, electrophoresis is the simple method as a decontamination method, and it is desirable to utilize zeolite with ion-exchange property as an inexpensive adsorbent. Ammonium acetate has been considered to be effective as an electrolyte because it has ammonium ion that has high ion-exchange reaction with cesium ion. However, an efficient decontamination cannot be achieved since the adsorption of cesium ions to zeolite is inhibited by ammonium ions. The purpose of this study is to discuss the efficient removal of cesium by using zeolite as an adsorbent and potassium acetate as an electrolyte through the electrophoresis test. From the test results, it is turned out that potassium acetate is suitable to extract cesium efficiently in electrophoresis.
Heavy metals with strong toxicity are often contained in mine drainage from the suspended or abandoned mines where mining activities were once conducted. The mine drainage continues to flow semipermanently. Thus the treatment of mine drainage must be continued. As the current treatment method for the mine drainage treatment, the neutralization treatment process utilizing alkali chemicals is mainly conducted. However, few alkali chemicals satisfy both low cost and high neutralizing ability. In addition, regarding the neutralized deposits generated during the treatment of mine drainage, it is difficult to secure the disposal sites. Moreover, in recent years, the metal demand has increased in IC chips and parts for electric vehicles. Thus, focusing on the rice husk which is an industrial waste, the purposes of this study are to verify the adsorption performance of rice husks for heavy metals and to verify whether the extraction of heavy metals from rice husks to which heavy metals are adsorbed is possible or not. In this study, the following two tests are carried out: The adsorption test of rice husk for heavy metals and the extraction test with acid from the rice husk which absorbs the heavy metals. From the test results, the adsorption isotherms of Zn, Cu and Cd on the rice husks are described from the adsorption tests, and the adsorption states of Zn, Cu and Cd on the rice husks are discussed. Furthermore, it is proved to be possible to extract them from the rice husks which adsorbs such heavy metals.
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