Publications (5)0 Total impact
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ABSTRACT: The deterioration of sediments is a serious environmental problem. Controlling nutrient release fluxes from sediments is important to alleviating eutrophication and to reducing terrigenous nutrient loads. The purpose of this study was to evaluate the phosphate removal performance of granulated coal ash (GCA) from seawater, which is produced from coal thermal electric power generation. Batch experiments were carried out to investigate the removal kinetics of phosphate from seawater under both oxic and anoxic conditions. Phosphate was removed well from seawater under both oxic and anoxic conditions. The adsorption isotherm for phosphate revealed that GCA could remove phosphate effectively from seawater above a concentration of 1.7 mu mol L-1. GCA can reduce the concentration of phosphate in seawater effectively under anoxic conditions where iron type adsorbents cannot be applied. Therefore, GCA could potentially be used to adsorb phosphate in the organically-enriched sediment, which generally occurs under highly reductive conditions.
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Satoshi Asaoka,
Tamiji Yamamoto,
Ichiro Yoshioka,
Hitoshi Tanaka,
サトシ アサオカ,
タミジ ヤマモト,
イチロウ ヨシオカ,
Ichirō Yoshioka,
ヒトシ タナカ, 聡 浅岡,
民次 山本,
一郎 吉岡,
等 田中
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ABSTRACT: It is very important to reduce phosphorus flux from sediment as well as cutting down terrigenous loads in order to control eutrophication in semi-enclosed coastal seas. Hydrogen sulfide is also a noxious substance which is highly toxic and fatal to benthic organisms. The purpose of this study is to evaluate remediation efficiency of organically enriched sediments using granulated coal ash (GCA) in terms of reducing benthic phosphorus flux and hydrogen sulfide. A flow-through experimental system was used to simulate the semi-enclosed water bodies. The application of GCA decreased the concentration of PO43- in the pore water effectively, and reduced phosphate releasing flux from the sediment into overlying water by 37-44% compared to the control. The hydrogen sulfide in the pore water was also decreased by 77-100%. due to adsorption onto the GCA and deactivation of sulfate-reducing bacteria due to increasing pH. Thus, GCA is a promising recycled material for reducing phosphate releasing flux from organically enriched sediment to alleviate eutrophication as well as reduce the concentration of hydrogen sulfide in pore water.
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ABSTRACT: Hydrogen sulfide is highly toxic and fatal to benthic organisms. It also depletes dissolved oxygen and generates blue tide when oxidized. Therefore, it should be controlled to maintain healthy ecosystems. The purpose of this study is to evaluate the removal of hydrogen sulfide from seawater using granulated coal ash produced from coal thermal electric power stations. The batch experiments revealed that the removal kinetics of hydrogen sulfide were expressed as a first-order rate equation and that the adsorption maximum of hydrogen sulfide was 108 mg-S · g-1. The K-edge X-ray adsorption fine structure spectra of sulfur adsorbed by granulated coal ash indicated that hydrogen sulfide was adsorbed as sulfur and formed FeS2 when the hydrogen sulfide concentration was high. Results imply that applying granulated coal ash to organically enriched sediment can effectively reduce the concentration of hydrogen sulfide in interstitial water.
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ABSTRACT: There is an urgent need to control nutrient release fluxes from organically-enriched sediments into overlying waters to alleviate the effects of eutrophication. This study aims to characterize blast furnace slag (BFS) and evaluate its remediation performance on organically-enriched sediments in terms of suppressing nutrient fluxes and reducing acid volatile sulfide. BFS was mainly composed of inorganic substances such as CaO, SiO2, Al2O3 and MgO in amorphous crystal phase. Container experiments showed that the phosphate concentration in the overlying water, its releasing flux from sediment and AVS of the sediment decreased by 17–23%, 39% and 16% compared to the control without BFS, respectively. The loss on ignition was significantly decreased by 3.6–11% compared to the control. Thus, the application of BFS to organically-enriched sediment has a suppressive role on organic matter, AVS concentration and phosphate releasing flux from sediments and therefore, is a good candidate as an effective environmental remediation agent.
