• Journal of Korean Society of Environmental Engineers
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• v.35 no.8
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• pp.598-606
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• 2013

This study was performed to determine whether biomineralization microbes were actively present underneath landfill cover soil producing biocalcification. From this, various types of microbes were observed. Among them, two species were dominantly found; Bacillus megaterium and Alkaliphilus metalliredigens that were known as biominerlization bacteria. With those microbes, $CO_2$ was more highly consumed than without bacteria. In response, the calcium carbonate mineral was produced at 30% (wt) greater than that of the control. At the same time, TG-DTA was successfully used for quantification of $CO_2$ consumed forming calcium carbonate minerals resulting from biocalcification. It was decided that the presence of solidified sewage sludge cake utilized as a cover soil in the landfill could efficiently contribute to possible media adaptably and naturally sequestering $CO_2$ producing from the landfill.

• Tunnel and Underground Space
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• v.20 no.5
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• pp.309-317
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• 2010

CCS (Carbon dioxide Capture and Storage) is a means of mitigating the contribution of $CO_2$ to the Greenhouse gas, from large point sources such as power plants and steel companies. CCS is a process whereby $CO_2$ is captured from gases produced by fossil fuel combustion, compressed, transported and injected into deep geologic formations for permanent storage. CCS applied to a conventional power plant can reduce $CO_2$ emissions to the atmosphere by approximately 80~90% compared to a plant without CCS. The IPCC estimates that the economic potential of CCS will be between 10% and 55% of the total carbon mitigation effort by year 2100. In this paper, overseas sites where CCS technology is being applied and technical development trends for CCS are briefly reviewed.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.12
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• pp.656-661
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• 2016

Manufacturing membrane materials with high selectivity and permeability is quite desirable but practically not possible, since the permeability and selectivity are usually inversely proportional. From the viewpoint of reducing the cost of $CO_2$ capture, module performance is even more important than the performance of membrane materials itself, which is affected by the permeance of the membrane (P, stagecut) and selectivity (S). As a typical example, when the mixture with a composition of 13% $CO_2$ and 87% of $N_2$ is fed into the module with 10% stage cut and selectivity 5, in the 10 parts of the permeate, $CO_2$ represents 4.28 parts and $N_2$ represents 5.72 parts. In this case, the $CO_2$ concentration in the permeate is 42.8% and the recovery rate of $CO_2$ in this first separation appears as 4.28/13 = 32.9%. When permeance and selectivity are doubled, however, from 10% to 20% and from 5 to 10, respectively, the $CO_2$ concentration in the permeant becomes 64.5% and the recovery rate is 12.9/13 = 99.2%. Since in this case, most of the $CO_2$ is separated, this may be the ideal condition. For a given feed concentration, the $CO_2$ concentration in the separated gas decreases if permeance is larger than the threshold value for complete recovery at a given selectivity. Conversely, for a given permeance, increasing the selectivity over the threshold value does not improve the process further. For a given initial feed gas concentration, if permeance or selectivity is larger than that required for the complete separation of $CO_2$, the process becomes less efficient. From all these considerations, we can see that there exists an optimum design for a given set of conditions.

• The Journal of Engineering Geology
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• v.28 no.2
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• pp.207-215
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• 2018

Almost all countries of the world have recently made great efforts to reduce green-house gases to alleviate the global warming threatening human survival, because a huge amount of carbon dioxide as one of the main green-house gases has been emitted from the combustion processes of fossil fuels such as coal and oil. $CO_2$ capture and storage (CCS) technology is a representative method to diminish the green-house gases, and actively investigated by many countries. This study focuses on the design and construction of a high pressure $CO_2$ injection facility to store it to underground, which is the first $CO_2$ injection in Korea following the steps of the $CO_2$ capture from large $CO_2$ emission sources and transportation to the sea. Injection tests of $CO_2$ on the platform on the sea were carried out in Yeongil Bay of Pohang city in the early 2017. Thus, we were able to perceive the necessary operating conditions of the injection facility, injection characteristic, and knowhow of the injection facility. The results obtained from the injection test shall be utilized for facility upgrades and scale-ups.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.12
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• pp.1268-1272
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• 2008

Low temperature plasma applied with partial oxidation is a technique to produce synthesis gas from methane. Low temperature plasma reformer has superior miniaturization and start-up characteristics to reformers using steam reforming or CO$_2$ reforming. In this research, a low temperature plasma reformer using GlidArc discharge was proposed. Reforming characteristics for each of the following variables were studied: gas components ratio (O$_2$/CH$_4$), the amount of steam, comparison of reaction on nickle and iron catalysts and the amount of CO$_2$. The optimum conditions for hydrogen production from methane was found. The maximum Hydrogen concentration of 41.1% was obtained under the following in this condition: O$_2$/C ratio of 0.64, total gas flow of 14.2 L/min, catalyst reactor temperature of 672$^{\circ}C$, the amount of steam was 0.8, reformer energy density of 1.1 kJ/L with Ni catalyst in the catalyst reactor. At this point, the methane conversion rate, hydrogen selectivity and reformer thermal efficiency were 66%, 93% and 35.2%, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.6
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• pp.332-338
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• 2017

The purpose of this study was to determine optimum value of aeration, acetate dosage, and $CO_2$ input for the cultivation of Scenedesmus acuminatus. Highest specific growth rate and maximum biomass productivity was obtained by the aeration of 0.72 vvm and lower specific growth rates and maximum biomass productivity were obtained for other aeration tests. When putting 0.3 M of ammonium acetate in JM medium, the highest specific growth rate and maximum biomass productivity were obtained. $CO_2$ input tests were performed during semi-continuous culturing tests. The highest specific growth rate ($0.460d^{-1}$) and maximum biomass productivity ($0.936gL^{-1}d^{-1}$) were obtained after replacing 50% of solution with 0.3 M of acetate solution for $CO_2$ input tests. However, more dilutions after the first dilution resulted in lower specific growth rate and maximum biomass productivity. In aeration tests, the highest specific growth rate ($0.381d^{-1}$) and maximum biomass productivity ($0.253gL^{-1}d^{-1}$) were obtained when cultivating it with JM medium, but the specific growth rate and maximum biomass producitivty were significantly decreased when 50% of solution was replaced by acetate containing solution.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.323-328
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• 2006

The purpose of this paper was to investigate the reforming characteristics and optimum operating condition of the GlidArc-assisted $C_3H_8$ reforming reaction for the synthesis gas(SynGas) production without formation of carbon black from propane using GildArc plasma reforming. Also, in order to increase the hydrogen production and the propane conversion rate, 13 wt % nickel catalyst was filled into the catalytic reactor and parametric screening studies were conducted, in which there were the variations of vapor mole ratio$(H_2O/C_3H_8),\;CO_2$ mole ratio($CO_2/C_3H_8$), input power and injection flow rate. When the variations of vapor mole ratio, $CO_2$ mole ratio, input power and injection flow rate were 1.86, 0.48, 1.37 kW and 14 L/min, respectively, the conversion rate of the propane reached its most optimal condition, or 62.6%. Under the condition mentioned above, the dry basic concentrations of the SynGas were $H_2\;44.4%,\;CO\;18.2%,\;CH_4\;11.2%,\;C_2H_2\;2.0%,\;C_3H_6\;1.6%,\;C_2H_4\;0.6%\;and\;C_3H_4$ 0.4%. The conversion rate of carbon dioxide was 29.2% and the concentration ratio of hydrogen to carbon monoxide($H_2/CO$) in the SynGas was 2.4.

• Journal of environmental and Sanitary engineering
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• v.13 no.1
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• pp.32-43
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• 1998

혐기성대상과정중 메탄생성균(methanogenic bacteria)에 의한 메탄생성시 주요 기질인 아세트산 (acetic acid)을 분해할 경우에 여러 가지 복합기질 중 아미노산 첨가에 의한 분해속도증가에 미치는 영향과 투입한 아미노산이 미생물에 의하여 생체량으로 합성되는 정도를 고찰하였다. 실험결과 메탄생성균은 glycine, serine, threonine, aspartic acid, trytophan 등의 혐기성미생물의 생체량합성에 필요한 물질을 투입할 경우에 아세트산의 분해속도가 증가하였으며, 여러 가지 아미노산을 혼합하여 주입한 결과 분해속도가 17% 향상되었다. 한편, 메탄생성균의 lysing에 의하여 생성된 유기물은 메탄이나 이산화탄소의 최종산물로 전환되기보다는 새로운 메탄생성균의 생체량을 형성하는데 직접 이용되었으며, 아세트산의 분해속도를 52% 증가시켰다. 단순기질(sole substrate)과 복합기질(complex substrate)의 분해는 미생물의 생체량합성에 필요한 여러 가지 중간대사산물간의 상호자극효과에 의하여 복합기질이 용이한 것으로 나타났으며, 유입기질내 활성이 강한 슬러지의 농도는 혐기성처리에 매우 중요한 부분을 차지하였다.

• Tunnel and Underground Space
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• v.18 no.3
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• pp.175-184
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• 2008

In this study, state-of-the-art of $CO_2$ geological sequestration as a method of greenhouse gas reduction was reviewed. Thermal-Hydraulic-Mechanically(THM) coupled simulation technology and its application to a stability analysis of geological formation due to $CO_2$ injection as well as a leakage path analysis were investigated and introduced.

• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.554-559
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• 2007

In order to improve the reactivity for the direct synthesis of dimethyl carbonate (DMC) using methanol and carbon dioxide, the various additives were used in the DMC synthesis using $Ce_{0.8}Zr_{0.2}O_2$ catalyst, and then effect of the additives was investigated. The various additives were molecular sieves 3A and the compounds having the various functional groups such as sulfate, carbonate, nitrate and phosphate. As a result, the compound such as $K_2SO_4$ and $Na_2SO_4$ having sulfate group were the most effective additive among the various additives. When $K_2SO_4$ was used as an additive in the direct synthesis of DMC, the amount of DMC was about 0.91 mmol, which was the highest mount of DMC among using only-$Ce_{0.8}Zr_{0.2}O_2$ catalyst and the various additives.