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- 저자 : ( Hiroki Kitamura ) (검색결과 12 건)
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( Hiroki Kitamura ),( Noppharit Sutthasil ),( Masato Ueshima ),( Seungki Back ),( Hirofumi Sakanakura ),( Tomonori Ishigaki ),( Masato Yamada ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 한국폐기물자원순환학회 심포지움 Vol.2019 No.1
Municipal solid waste incineration (MSWI) fly ash is usually classified as hazardous waste owing to high contents of toxic metals such as Pb. In Japan, chelating treatment is mainly used to immobilize toxic metals. However, unreacted and/or remained chelating reagent in leachate at landfill causes long-tern leachate treatment owing to COD component and nitrification inhibition. Thus, stabilization of landfill site is delayed. Therefore, new metal immobilization method is desirable instead of chelating treatment or in order to reduce the amount of chelating reagent. In this context, this study investigated the effect of mineralogical immobilization, in particular synthesized and neoformed ettringite (3CaO·Al<sub>2</sub>O<sub>3</sub>·3CaSO<sub>4</sub>·32H<sub>2</sub>O), on toxic metals in MSWI fly ash. MSWI fly ash sample used in this study was collected from bag filter of a stoker-type MSW incinerator in Japan. The incineration capacity is 80 tons/day. Ettringite was synthesized by mixing 0.02 mol/L Ca(OH)<sub>2</sub> solution and 0.7 mol/L Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>·14-18H<sub>2</sub>O solution in sealed plastic bottle in order to avoid CO<sub>2</sub> via atomosphere. The mixing volume of these solutions were theoretically decided according to molar ratio of Ca/Al (= 6) in ettringite. After mixing the solutions by magnetic stirrer for 24 hours, synthesized ettringite was collected by vacum filtration and dried at room temperature. Synthesized ettringite was added to MSWI fly ash sample at different dosage (0%, 5%, 25%, 50%, and 100% of fly ash weight). In the case of neoformed ettringite, powdary Ca(OH)<sub>2</sub> and Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>·14-18H<sub>2</sub>O were added to MSWI fly ash. The amount of powdery additives were stoichiometrically decided in order to form the same amount as synthesized ettringite added to MSWI fly ash. Then, these mixtures were subjected to leaching experiments. The mixture added distilled water were shaken at 200 rpm for 6 hours in leaching test bottle. The liquid to solid (fly ash) ratio was 10. After shaking the bottle, the suspension was filtrated through 0.45 μm membrane filter in order to obtain leachate. Leaching concentrations of regulated heavy metals (As, Cd, Cr, Pb, and Se) in leachate were measured by ICP-MS and -OES. The results showed that only Pb concentration exeeded regulated limit ( > 0.3 mg/L). Concentration of As and Cd were lower than regulated limits (0.3 mg/L and 1.5 mg/L, respectively). Concentrations of Cd and Se were below detection limit in this analysis (0.4 μg/L and 3.0 μg/L, respectively). Lead concentration in leachate is shown in Figure 1. Leaching concentration of Pb slightly decreased until at 25 % dosage (see Figure 1-A). Lead leaching from MSWI fly ash strongly depends on pH value. However, leachate pH at all conditions added synthesized ettringite as well as neoformed ettringite was almost equal to 11.9. Therefore, this result suggests that Pb was immobilized by synthesized ettringite through interaction with negatively charged ettringite surface and/or substitution of Ca<sup>2+</sup> ion in ettringite structure during leaching experiment. In contrast, leaching concentration of Pb under neoformed ettringite was significantly lower than that under synthesized ettringite (see Figure 1-B). It is considered that Pb was efficiently incorporated into ettringite structure and immobilized by ettringite neoformation during leaching experiment. This means that selectively forming ettringite into MSWI fly ash might have possibility of mineralogical metal immobilization.
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( Hiroki Kitamura ),( Astryd Viandila Dahlan ),( Yu Tian ),( Takashi Yamamoto ),( Fumitake Takahashi ) 한국폐기물자원순환학회(구 한국폐기물학회) 2017 한국폐기물자원순환학회 심포지움 Vol.2017 No.1
Municipal solid waste incineration (MSWI) fly ash is considered as hazardous waste owing to toxic characteristics of heavy metals. In Japan, chelate treatment is mainly used to reduce their toxicity. However, the impacts of morphological and/or heterogeneous characteristics of MSWI fly ash on leaching behaviour of heavy metals are still uncertain. Therefore, this study investigated heterogeneity of the surface and inner matrices of chelate-treated MSWI fly ash particles at micro scale level for fly ash characterization. Chelate-treated MSWI fly ash, which are collected from a Japanese MSWI facility plant equipped with stoker-type incinerator (incineration capacity : 250 Mg/d), were analyzed in order to investigate heterogeneity of the particle surface. Residual materials after acid extraction (Japan Leaching test 19th, JLT19) were also analyzed in order to investigate heterogeneity of inner matrices. Morphology and elemental distributions on the surfaces of MSWI fly ash particle were investigated by scanning electron microscope (SEM) and energy dispersive X-ray analyzer (EDX). One hundred chelate- treated MSWI fly ash particles and residual materials after JLT19 were analyzed, respectively. Line profile analysis was conducted on one fly ash particle surface, which is divided to 5 sections uniformly, in order to measure relative intensity of major elements. Coefficient of variation (CV value) was calculated based on obtained relative intensity in order to quantify heterogeneity of individual particles. Area analysis was also conducted in order to measure elemental concentration on particle surfaces as weight percent (wt%) and evaluate heterogeneity among fly ash particles. Elemental mapping by EDX showed that chelate-treated MSWI fly ash particles consist mainly of Al, Ca, Cl, K, Mg, Na, O, S and Si. In contrast, residual materials consist mainly of Al/Ca/Si-based matrices owing to leaching of soluble components such as KC1 and NaCl by JLT19. Calculated CV values and measured weight percent of inner matrices (Al, Ca, and Si) are shown in Figure 1. According to heterogeneity analysis, CV values of inner matrices were in the range of 0 to 1.0. However, large differences of CV values between chelate-treated MSWI fly ash and residual materials were not observed although the particle surfaces are covered by soluble components before JLT19. The A1 and Si weight percent of residual materials increased relatively in comparison with chelate-treated MSWI fly ash owing to leaching of soluble and semi-soluble components. In addition, their weight percent distributed widely after JLT19. This means that they have large heterogeneous characteristics among fly ash particles. In some case, residual materials (aluminosilicate) also had complicated structure such as skeleton. Therefore, these results showed that morphological and heterogeneous characteristics might have impacts on leaching behavior of heavy metals.
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( Hiroki Kitamura ),( Takayuki Shimaoka ),( Fumitake Takahashi ) 한국폐기물자원순환학회(구 한국폐기물학회) 2015 한국폐기물자원순환학회 3RINCs초록집 Vol.2015 No.-
Immobilization effect of chelate treatment was investigated using leaching experiments. Chemical forms of immobilized heavy metals in chelate treated municipal solid waste incineration (MSWI) fly ash were also investigated. Leaching experiments showed that heavy metals in chelate-treated MSWI fly ash are immobilized except for Cu. Some of Cu was incorporated into crystal structure of ettringite generated by chelate treatment. However, immobilization effect by ettringite might be limited. Chemical forms of heavy metals in chelate-treated MSWI fly ash seems to be oxides, sulfate or chlorides. Heavy metal particle sizes are several ten μm scale and concentrated spots of heavy metals were not mostly observed. Therefore, heavy metals seem to be distributed widely and tenuously on fly ash particle.
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( Hiroki Kitamura ),( Astryd Viandila Dahlan ),( Fumitake Takahashi ) 한국폐기물자원순환학회(구 한국폐기물학회) 2016 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2016 No.-
In Japan, municipal solid waste incineration (MSWI) fly ash is landfilled after immobilization treatment owing to high contents of heavy metals. Major treatment method is chelate treatment. Its immobilization mechanism is considered as complexation between chelating substances and heavy metals. Although mineralogical characteristics of MSWI fly ash are changed dramatically by secondary mineral formation in chelate treatment process, MSWI fly ash has been considered as homogeneous because fly ash is fine particles. However, micro-characteristics of fly ash might have non-negligible impact on leaching behavior of heavy metals if fly ash is heterogeneous. Therefore, this study investigated heterogeneity of raw and chelate-treated MSWI fly ash particles by elemental line profile analysis. Experimental samples are raw and chelate-treated MSWI fly ash collected from a Japanese MSWI facility plant equipped with stoker-type incinerator (incineration capacity : 250 Mg/d). Elemental mapping was conducted to investigate elemental distribution of fly ash particles by scanning electron microscope (SEM) equipped with energy dispersive X-ray analyzer (EDX). After elemental mapping, the surface of a fly ash particle was divided to 5 sections from the side to the other side horizontally. Line profile analysis was conducted at each divided section to analyze relative intensity of constituent elements. The coefficient of variation (C.V) of each element was calculated based on line profiles to evaluate heterogeneity in each particle. Elemental mapping showed that raw and chelate-treated MSWI fly ash particles consist mainly of Al, Ca, Cl, Na, O, and Si. In some cases, they contained other elements (K, Mg, and S) as well as heavy metals (e.g. Cr, Fe, Mn, Ti, and Zn). Calculated C.V. of major elements are shown in histogram (see Fig. 1). The C.V of Al, Na, O, and Si are mainly distributed in the range of 0 to 0.8. However, they often distributed around 1.0. Therefore, these elements seem to be heterogeneous in each particle. The C.V. of Ca are distributed in the range of 0 to 0.5. Therefore, Ca seems to be slightly heterogeneous in each particle. On the other hand, the C.V. of Cl are distributed widely. This means that Cl is very heterogeneous in each particle. As a result, these results suggest that a MSWI fly ash particle is heterogeneous although it has been considered as homogeneous without sufficient observations. In addition, its heterogeneity might have non-negligible impact on leaching behaviors of heavy metals. Line profile analysis is useful for micro-scale characterization of MSWI fly ash particles. However, only 51 particles were analyzed in this study. Therefore, further observations are required to homogenize experimental results.
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( Astryd Yiandila Dahlan Hiroki Kitamura ),( Yu Tian ),( Hirofumi Sakanakura ),( Takashi Yamamoto ),( Fumitake Takahashi ) 한국폐기물자원순환학회(구 한국폐기물학회) 2018 한국폐기물자원순환학회 심포지움 Vol.2018 No.1
Incineration is major treatment method of municipal solid waste (MSW) in Japan to reduce volume and weight of the waste. In 2016, total MSW generation in Japan was about 43.17 million tons and around 80 % of MSW were combusted by incinerators. Bottom ash and fly ash are the main products from MSW incinerators. MSW incineration fly ash is categorized as hazardous waste due to high concentration of leachable toxic heavy metals and the presence of toxic organic compounds like dioxins. Although MSWI fly ash is fine particles and has been regarded as homogeneous in numerous previous researches, it has not been proved based on sufficient analysis in the micro-scale. Therefore, the objective of the study is to investigate particle-scale heterogeneity of fly ash, in particular heterogeneity among fly ash particles (interparticle heterogeneity). In this study, fly ash generated from a fluidized bed and stoker combustor were analyzed and compared. Surface elemental concentrations of each fly ash particles, measured by SEM-EDS, were used to analyze elemental heterogeneity among fly ash particles. In order to measure interparticle heterogeneity of inner matrices of fly ash particles, Japan leaching test 19th (JLT 19), which used hydrochloric acid as leaching medium with liquid-to-solid ratio of 33.3, were conducted to remove semi-soluble and soluble components of fly ash particles. For each sample of stoker incinerator fly ash, fluidized bed incinerator fly ash, and their insoluble residues of JLT 19, 100 particles were measured. Elemental binary molar ratio among Ca, Si and A1 were plotted in ternary diagrams to visualize interparticle heterogeneity. Major elements in fly ash particles generated from both incinerators have large distributions of elemental concentrations. On the other hand, there are not significant differences of elemental concentration distribution between both incinerator fly ash excluding calcium (Ca). Ca concentration in fluidized bed combustor is relatively higher than stoker combustor. Ca concentration distribution of fluidized bed incinerator fly ash is wider than that of stoker combustor fly ash. Elemental ratios among Ca, Si and Al, plotted in triangular graphs, clearly shows that fly ash particles produced from stoker combustor concentrated in Ca area. On the other hand, fly ash of fluidized bed incinerator are dispersed more to Ca and Si sides as shown in Figure 1. This means that fly ash of fluidized bed incinerator has larger interparticle elemental heterogeneity compared to stoker combustor fly ash although different waste streams might have caused this difference to some extent. Fly ash residues of JLT 19 are relatively concentrated in Si area compared to fly ash particle surfaces. The authors expected that most of residue samples would be plotted near Si area. However, some particles spread to Ca and A1 areas. Moreover, fly ash of stoker incinerator has more scattered plots than fluidized bed incinerator fly ash. In contrast to interparticle elemental heterogeneity on fly ash surfaces, insoluble inner matrices of stoker incinerator fly ash have larger interparticle heterogeneity than fluidized bed incinerator fly ash. These analysis results would be useful for not only evaluation of fly ash heterogeneity but also considerations of fly ash formation mechanisms.
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( Yu Tian ),( Hiroki Kitamura ),( Astryd Viandila Dahlan ),( Takashi Yamamoto ),( Fumitake Takahashi ) 한국폐기물자원순환학회(구 한국폐기물학회) 2017 한국폐기물자원순환학회 심포지움 Vol.2017 No.1
Municipal solid wastes incineration (MSWI) is a commonly accepted solution in Japan for waste management by municipalities. The main products after incineration are bottom ash (BA) and fly ash (FA). The fly ash is cargorized as hazardous waste owing to high contents of heavy metals and toxic organic compounds like dioxin. It is necessary to take some immobilization treatment before landfill disposal of fly ash. The major treatment method in Japan is organic treatments such as chelating treatment. In this process, the authors found secondary mineral formations on fly ash surfaces. Because chelate reagents for organic treatment can be decomposed within several years and cause high concentraions of organic carbon in landfill leachate, this research focuses on inorganic treatments for stable immobilize of toxic elements. In this study, MSWI fly ash sample was collected from a Japanese MSWI facility plant. Materials used in this research are chelate-treated MSWI fly ash, and three kinds of inorganic reagents. They are sodium carbonate (0.01mol/L), sodium phosphate (0.01mol/L) and sodium sulfate (0.01mol/L). In organic treatment, sodium solutions were mixed with fly ash at the solid to liquid (L/S) ratio of 1. Moistened samples were dried at room temperature about 20 °C for about 5 days. X-Ray Diffraction (XRD) method was used to detect major secodaiy minerals. Scanning Electron Microscope (SEM) was used to observe the surface morphology of fly ash particles and Energy Dispersive X-Ray analyzer (EDX) equipped with SEM was used to measure elemental distribtuions of fly ash particle surfaces. According to the experiment results of XRD, the main crystals were sylvite, halite, anhydrite, gypsum, calcite and quartz. There is no significant difference bteween raw and inorganic-treated MSWI fly ash. It suggests that inorganic treatment did not promote secondary mineral formations which were detecable by XRD. SEM-EDX analysis showed that raw, chelate-treated and inorganic-treated MSWI fly ash particles consist mainly of Na, K, Cl, Ca, Al, and Si. According to SEM observations, significant differences of surface morphology of fly ash after inorganic treatment were not found in spite of chelate-treated MSWI fly ash. Although inomgaic treatments were expected to promote the formations of calcite (CaCO<sub>3</sub>), gypsum (CaSO<sub>4</sub>·2H<sub>2</sub>O) and apatite (Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH)<sub>2</sub>), experimental conditions should be improved in particular water content, pH, and reaction time.
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( Naoto Mizobuchi ),( Hiroki Kambe ),( Eriko Matsumura ),( Takaaki Kitamura ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-
Depletion of fossil fuel has become a serious problem by accelerating motorization in Asian countries. Furthermore, regulations on exhaust gas such as Particulate Matter (PM) and Nitrogen oxides (NOx) emitted from internal combustion engine are being strengthened year by year. Then, recent diesel engines are equipped with Diesel Particulate Filter (DPF) as after treatment device for exhaust gas, and PM is collected. However, with the long-term use of DPF, PM accumulates in DPF. As a result, PM collection efficiency deteriorates and pressure loss increases. Therefore, post injection has attracted attention as DPF regeneration method for burning and removing PM in DPF. In post injection, fuel is injected into the cylinder at the middle to late stage of expansion stroke, and unburned hydrocarbon is supplied to the Diesel Oxidation Catalyst (DOC). Then, oxidation heat is generated by oxidation reaction of unburned hydrocarbon and DOC. And the oxidation heat flows into the DPF, thereby burning and removing PM. However, oil dilution to the lubricating oil film on cylinder liner caused by post injection is a serious problem. Because oil dilution is leading to deterioration of sliding properties of piston and thermal efficiency, it is necessary to clarify spray impingement behavior on lubricating oil film. So in this research, we focus on the oil dilution phenomenon caused by post injection and aim for modeling oil dilution phenomenon. In this report, we measured the critical weber number which makes it possible to judge whether or not fuel droplets impinging on lubricating oil film deposits or splash. As a result, it was found that fuel droplets impingement behavior on lubricating oil film is classified into three behaviors by two critical weber numbers. First, We<sub>crP</sub> =(272+11600δ<sub>non</sub><sup>1.29</sup>)Lα<sup>0.01</sup>,second, We<sub>crS</sub> =(235+2255δ<sub>non</sub><sup>1.05</sup>)Lα<sup>0.05</sup>, La=ρ<sub>ο</sub>·σ<sub>ο</sub>·d<sub>in</sub>/μ<sub>ο</sub><sup>2</sup>, Here, ρ<sub>ο</sub> is density of engine oil, σ<sub>ο</sub> is surface tension of engine oil, μ<sub>ο</sub> is viscosity coefficient of engine oil, and Lα is Laplace number.
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