ABSTRACT In this study, we investigated the effect of silt and clay in the sediment on the settle... more ABSTRACT In this study, we investigated the effect of silt and clay in the sediment on the settlement of Ruditapes philippinarum larvae. Mountain, river and sea sands of which silt and clay (< 0.075 mm) content was adjusted using silt and clay originating from these sands or dredged sediment (DS) were examined for settlement of R. philippinarum larvae. The addition of DS and Otagawa river sand-originated silt and clay did not accelerate the larval settlement, whereas the mountain and Jigozen sea sands-originated silt and clay promoted larval settlement at 5%. The negative impact of Otagawa river sand-originated silt and clay might be due to its high leachability of Mn, while the accelerated larval settlement by Jigozen sea sands-originated silt and clay could be attributed to its organic contents. The provided results indicate that a suitable ratio of the fine particles to coarse particles exists for the acceleration of the larval settlement, though the effect might be dependent on their chemical properties.
ABSTRACT Sea grass beds and tidal flats are facing imminent dangers of extinction. Steel slags ar... more ABSTRACT Sea grass beds and tidal flats are facing imminent dangers of extinction. Steel slags are one of the promising alternative materials for marine sands to restore sea grass beds and tidal flats. On the other hand, significant pH increase and solidification attributed to dissolving calcium released from the slags are sometimes negative impact on ecosystems. To quantify the dissolved calcium, Japan Cement Association Standard method is conventionally used. However, our study leveled the method underestimate the dissolved calcium from the steel slags. The purpose of this study is to optimize the determination method for maximum calcium releasing potential from steel slags. Powdered sample (0.1 g) was stirred in 40 mL of 99.5% ethyleneglycol-100 mM tris buffer solution for 6 h at 80±5°C. Thereafter, the solution filter through 0.45 μm filter and the dissolved calcium was determined by ICP-AES. The optimized condition proposed in this study recovered the dissolved calcium from the slag in seawater perfectly.
In the present work, the use of nano-metallic calcium (Ca) and calcium oxide (CaO) dispersion mix... more In the present work, the use of nano-metallic calcium (Ca) and calcium oxide (CaO) dispersion mixture for the immobilization of heavy metals (As, Cd, Cr and Pb) in soil was investigated. With simple grinding, 85-90% of heavy metals immobilization could be achieved, while it could be enhanced to 98-100% by grinding with the addition of nano-metallic Ca/CaO dispersion mixture. By SEM-EDS elemental maps as well as semi-quantitative analysis observed that the amount of As, Cd, Cr and Pb measurable on soil particle surface decreases after nano-metallic Ca/CaO treatment. The leachable heavy metals concentrations were reduced, to the concentration lower than the Japan soil elution standard regulatory threshold, i. e., < 0.01 mg/l for As, Cd and Pb and 0.05mg/l for Cr. Whereas, the effect of soil moisture and pH on heavy metals immobilization was not much influenced. The results suggest that nano-metallic Ca/CaO mixture is suitable to be used for the gentle immobilization of heavy metals contaminated soil at normal moisture conditions.
Thermophilic and aerobia digestion (TAD) of sewage sludge was performed using Chamaecyparis obtus... more Thermophilic and aerobia digestion (TAD) of sewage sludge was performed using Chamaecyparis obtusa, Cryptomeria japonica, and Pinus densiflora wood chips to confirm Physical and chemical properties of woody bulking agents affecting digestion efficiency. About 60% of digestion efficiency was attained by the C. obtusa and C. japonica wood chips, while that by P. densiflora was only 40%. Neither the difference of porous structure nor inclusion of anti-bacterial substances accounted for the different digestion efficiencies. P. densiflora wood chips have the highest acid leachability, and we finally confirmed that lowering pH to 6 was responsible for the lowest digestion efficiency.
In problems of system analysis, it is customary to treat imprecision by the use of probability th... more In problems of system analysis, it is customary to treat imprecision by the use of probability theory. It is becoming increasingly clear, however, that in the case of many real world problems involving large scale systems such as economic systems, social systems, mass service systems, etc., the major source of imprecision should more properly be labeled ‘fuzziness’ rather than ‘randomness.’ By fuzziness, we mean the type of imprecision which is associated with the lack of sharp transition from membership to nonmembership, as in tall men, small numbers, likely events, etc. In this paper our main concern is with the application of the theory of fuzzy sets to decision problems involving fuzzy goals and strategies, etc., as defined by R. E. Bellman and L. A. Zadeh [1]. However, in our approach, the emphasis is on mathematical programming and the use of the concept of a level set to extend some of the classical results to problems involving fuzzy constraints and objective functions.
Perfluorocarboxylic acids (PFCAs) such as perfluorooctanoic acid (C 7 F 15 COOH, PFOA) have been ... more Perfluorocarboxylic acids (PFCAs) such as perfluorooctanoic acid (C 7 F 15 COOH, PFOA) have been used widely as products or raw materials for surfactants, surface treatment agents, and so forth because of their high interfacial activity, high thermal and chemical stability, and high light transparency 1,2 .
Present study, first time we developed a nano-Fe/Ca/CaO dispersion mixture based remediation and ... more Present study, first time we developed a nano-Fe/Ca/CaO dispersion mixture based remediation and volume reduction method of real radioactive cesium contaminated soils. After soil samples treated with 10wt% of nano-Fe/Ca/CaO dispersion mixtures, emitting radiation intensity was reduced from 4.00 µSv/h to 0.95 µSv/h in non-magnetic fraction soils. While, after treatment, about 30wt% magnetic and 70wt% non-magnetic fraction soils were separated, and it's condensed radioactive cesium concentration was about 80% and 20%, respectively. By this way, cesium contaminated soil volume can be reduced. These preliminary results appear to be very promising and the simple mixing with the addition of nano-Fe/Ca/CaO may be considered potentially applicable for the remediation and separation of radioactive Cs contaminated soil in dry conditions.
Cleaning-in-Place (CIP) in the beverage industry is typically carried out in production lines wit... more Cleaning-in-Place (CIP) in the beverage industry is typically carried out in production lines with alkaline and acidic solutions with detergents. This cleaning not only produces alkaline and acidic wastewater with detergents but also takes significant time. One of the important targets for CIP is adsorbed odorous compounds on gaskets, hence, we have tried to establish a rapid and green CIP process to remove traces of such compounds, especially d-limonene, an odorous component of orange juice, using two approaches; an ozone cleaning method and a change of gasket material from ethylene propylene diene monomer (EPDM) rubber to silicone rubber. By changing the gasket material from EPDM rubber to silicone rubber, the removability of d-limonene by typical alkaline and acidic cleanings with detergents was improved. However, complete removal of 4mgg(-1) of d-limonene on both EPDM and silicone gaskets could not be achieved even using a series of conventional cleaning procedures that included...
The performance of a ferric ion mediated photochemical process for perfluorooctanoic acid (PFOA) ... more The performance of a ferric ion mediated photochemical process for perfluorooctanoic acid (PFOA) decomposition in strongly acidic conditions of pH 2.0 was evaluated in comparison with those in weakly acidic conditions, pH 3.7 or pH 5.0, based on iron species composition and ferric ion regeneration. Complete decomposition of PFOA under UV irradiation was confirmed at pH 2.0, whereas perfluoroheptanoic acid (PFHpA) and other intermediates were accumulated in weakly acidic conditions. Iron states at each pH were evaluated using a chemical equilibrium model, Visual MINTEQ. The main iron species at pH 2.0 is Fe3+ ion. Although Fe3+ ion is consumed and is transformed to Fe2+ ion by photochemical decomposition of PFOA and its intermediates, the produced Fe2+ ion will change to Fe3+ ion to restore chemical equilibrium. Continuous decomposition will occur at pH 2.0. However, half of the iron cannot be dissolved at pH 3.7. The main species of dissolved iron is Fe(OH)2+. At pH 3.7 or higher pH...
Sediment sludge during coagulation and sedimentation in drinking water treatment is called &a... more Sediment sludge during coagulation and sedimentation in drinking water treatment is called &amp;amp;amp;amp;quot;water treatment residuals (WTR)&amp;amp;amp;amp;quot;. Polyaluminum chloride (PAC) is mainly used as a coagulant in Japan. The recycling of WTR has been desired; one method for its reuse is as plowed soil. However, WTR reuse in this way is inhibited by the aluminum from the added PAC, because of its high adsorption capacity for phosphate and other fertilizer components. The removal of such aluminum from WTR would therefore be advantageous for its reuse as plowed soil; this research clarified the effect of acid washing on aluminum removal from WTR and on plant growth in the treated soil. The percentage of aluminum removal from raw WTR by sulphuric acid solution was around 90% at pH 3, the percentage decreasing to 40% in the case of a sun-dried sample. The maximum phosphate adsorption capacity was decreased and the available phosphorus was increased by acid washing, with 90% of aluminum removal. The enhancement of Japanese mustard spinach growth and the increased in plant uptake of phosphates following acid washing were observed.
ABSTRACT In this study, we investigated the effect of silt and clay in the sediment on the settle... more ABSTRACT In this study, we investigated the effect of silt and clay in the sediment on the settlement of Ruditapes philippinarum larvae. Mountain, river and sea sands of which silt and clay (&lt; 0.075 mm) content was adjusted using silt and clay originating from these sands or dredged sediment (DS) were examined for settlement of R. philippinarum larvae. The addition of DS and Otagawa river sand-originated silt and clay did not accelerate the larval settlement, whereas the mountain and Jigozen sea sands-originated silt and clay promoted larval settlement at 5%. The negative impact of Otagawa river sand-originated silt and clay might be due to its high leachability of Mn, while the accelerated larval settlement by Jigozen sea sands-originated silt and clay could be attributed to its organic contents. The provided results indicate that a suitable ratio of the fine particles to coarse particles exists for the acceleration of the larval settlement, though the effect might be dependent on their chemical properties.
ABSTRACT Sea grass beds and tidal flats are facing imminent dangers of extinction. Steel slags ar... more ABSTRACT Sea grass beds and tidal flats are facing imminent dangers of extinction. Steel slags are one of the promising alternative materials for marine sands to restore sea grass beds and tidal flats. On the other hand, significant pH increase and solidification attributed to dissolving calcium released from the slags are sometimes negative impact on ecosystems. To quantify the dissolved calcium, Japan Cement Association Standard method is conventionally used. However, our study leveled the method underestimate the dissolved calcium from the steel slags. The purpose of this study is to optimize the determination method for maximum calcium releasing potential from steel slags. Powdered sample (0.1 g) was stirred in 40 mL of 99.5% ethyleneglycol-100 mM tris buffer solution for 6 h at 80±5°C. Thereafter, the solution filter through 0.45 μm filter and the dissolved calcium was determined by ICP-AES. The optimized condition proposed in this study recovered the dissolved calcium from the slag in seawater perfectly.
In the present work, the use of nano-metallic calcium (Ca) and calcium oxide (CaO) dispersion mix... more In the present work, the use of nano-metallic calcium (Ca) and calcium oxide (CaO) dispersion mixture for the immobilization of heavy metals (As, Cd, Cr and Pb) in soil was investigated. With simple grinding, 85-90% of heavy metals immobilization could be achieved, while it could be enhanced to 98-100% by grinding with the addition of nano-metallic Ca/CaO dispersion mixture. By SEM-EDS elemental maps as well as semi-quantitative analysis observed that the amount of As, Cd, Cr and Pb measurable on soil particle surface decreases after nano-metallic Ca/CaO treatment. The leachable heavy metals concentrations were reduced, to the concentration lower than the Japan soil elution standard regulatory threshold, i. e., < 0.01 mg/l for As, Cd and Pb and 0.05mg/l for Cr. Whereas, the effect of soil moisture and pH on heavy metals immobilization was not much influenced. The results suggest that nano-metallic Ca/CaO mixture is suitable to be used for the gentle immobilization of heavy metals contaminated soil at normal moisture conditions.
Thermophilic and aerobia digestion (TAD) of sewage sludge was performed using Chamaecyparis obtus... more Thermophilic and aerobia digestion (TAD) of sewage sludge was performed using Chamaecyparis obtusa, Cryptomeria japonica, and Pinus densiflora wood chips to confirm Physical and chemical properties of woody bulking agents affecting digestion efficiency. About 60% of digestion efficiency was attained by the C. obtusa and C. japonica wood chips, while that by P. densiflora was only 40%. Neither the difference of porous structure nor inclusion of anti-bacterial substances accounted for the different digestion efficiencies. P. densiflora wood chips have the highest acid leachability, and we finally confirmed that lowering pH to 6 was responsible for the lowest digestion efficiency.
In problems of system analysis, it is customary to treat imprecision by the use of probability th... more In problems of system analysis, it is customary to treat imprecision by the use of probability theory. It is becoming increasingly clear, however, that in the case of many real world problems involving large scale systems such as economic systems, social systems, mass service systems, etc., the major source of imprecision should more properly be labeled ‘fuzziness’ rather than ‘randomness.’ By fuzziness, we mean the type of imprecision which is associated with the lack of sharp transition from membership to nonmembership, as in tall men, small numbers, likely events, etc. In this paper our main concern is with the application of the theory of fuzzy sets to decision problems involving fuzzy goals and strategies, etc., as defined by R. E. Bellman and L. A. Zadeh [1]. However, in our approach, the emphasis is on mathematical programming and the use of the concept of a level set to extend some of the classical results to problems involving fuzzy constraints and objective functions.
Perfluorocarboxylic acids (PFCAs) such as perfluorooctanoic acid (C 7 F 15 COOH, PFOA) have been ... more Perfluorocarboxylic acids (PFCAs) such as perfluorooctanoic acid (C 7 F 15 COOH, PFOA) have been used widely as products or raw materials for surfactants, surface treatment agents, and so forth because of their high interfacial activity, high thermal and chemical stability, and high light transparency 1,2 .
Present study, first time we developed a nano-Fe/Ca/CaO dispersion mixture based remediation and ... more Present study, first time we developed a nano-Fe/Ca/CaO dispersion mixture based remediation and volume reduction method of real radioactive cesium contaminated soils. After soil samples treated with 10wt% of nano-Fe/Ca/CaO dispersion mixtures, emitting radiation intensity was reduced from 4.00 µSv/h to 0.95 µSv/h in non-magnetic fraction soils. While, after treatment, about 30wt% magnetic and 70wt% non-magnetic fraction soils were separated, and it's condensed radioactive cesium concentration was about 80% and 20%, respectively. By this way, cesium contaminated soil volume can be reduced. These preliminary results appear to be very promising and the simple mixing with the addition of nano-Fe/Ca/CaO may be considered potentially applicable for the remediation and separation of radioactive Cs contaminated soil in dry conditions.
Cleaning-in-Place (CIP) in the beverage industry is typically carried out in production lines wit... more Cleaning-in-Place (CIP) in the beverage industry is typically carried out in production lines with alkaline and acidic solutions with detergents. This cleaning not only produces alkaline and acidic wastewater with detergents but also takes significant time. One of the important targets for CIP is adsorbed odorous compounds on gaskets, hence, we have tried to establish a rapid and green CIP process to remove traces of such compounds, especially d-limonene, an odorous component of orange juice, using two approaches; an ozone cleaning method and a change of gasket material from ethylene propylene diene monomer (EPDM) rubber to silicone rubber. By changing the gasket material from EPDM rubber to silicone rubber, the removability of d-limonene by typical alkaline and acidic cleanings with detergents was improved. However, complete removal of 4mgg(-1) of d-limonene on both EPDM and silicone gaskets could not be achieved even using a series of conventional cleaning procedures that included...
The performance of a ferric ion mediated photochemical process for perfluorooctanoic acid (PFOA) ... more The performance of a ferric ion mediated photochemical process for perfluorooctanoic acid (PFOA) decomposition in strongly acidic conditions of pH 2.0 was evaluated in comparison with those in weakly acidic conditions, pH 3.7 or pH 5.0, based on iron species composition and ferric ion regeneration. Complete decomposition of PFOA under UV irradiation was confirmed at pH 2.0, whereas perfluoroheptanoic acid (PFHpA) and other intermediates were accumulated in weakly acidic conditions. Iron states at each pH were evaluated using a chemical equilibrium model, Visual MINTEQ. The main iron species at pH 2.0 is Fe3+ ion. Although Fe3+ ion is consumed and is transformed to Fe2+ ion by photochemical decomposition of PFOA and its intermediates, the produced Fe2+ ion will change to Fe3+ ion to restore chemical equilibrium. Continuous decomposition will occur at pH 2.0. However, half of the iron cannot be dissolved at pH 3.7. The main species of dissolved iron is Fe(OH)2+. At pH 3.7 or higher pH...
Sediment sludge during coagulation and sedimentation in drinking water treatment is called &a... more Sediment sludge during coagulation and sedimentation in drinking water treatment is called &amp;amp;amp;amp;quot;water treatment residuals (WTR)&amp;amp;amp;amp;quot;. Polyaluminum chloride (PAC) is mainly used as a coagulant in Japan. The recycling of WTR has been desired; one method for its reuse is as plowed soil. However, WTR reuse in this way is inhibited by the aluminum from the added PAC, because of its high adsorption capacity for phosphate and other fertilizer components. The removal of such aluminum from WTR would therefore be advantageous for its reuse as plowed soil; this research clarified the effect of acid washing on aluminum removal from WTR and on plant growth in the treated soil. The percentage of aluminum removal from raw WTR by sulphuric acid solution was around 90% at pH 3, the percentage decreasing to 40% in the case of a sun-dried sample. The maximum phosphate adsorption capacity was decreased and the available phosphorus was increased by acid washing, with 90% of aluminum removal. The enhancement of Japanese mustard spinach growth and the increased in plant uptake of phosphates following acid washing were observed.
Uploads
Papers by Tetsuji Okuda