• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.389-390
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• 2000

최근 지구 온난화의 55% 이상을 차지하고 있는 이산화탄소를 유용한 화합물로 전환하고자 메탄을 환원제로 사용한 이산화탄소 개질반응으로부터 합성가스 생성에 관한 연구가 활발히 진행되고 있다. 메탄의 이산화탄소 개질반응은 수증기 개질반응보다 낮은 합성 가스비의 생성, 온실효과를 유발하는 이산화탄소의 저감, 반응의 높은 흡열도를 이용한 화학에너지 전송 시스템의 응용 면에서 그 의의가 있다. (중략)

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.780-787
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• 2019

As a carbon-free, green growth alternative, internal and external interest in hydrogen energy and technology is growing. Hydrogen was added to co-axial methane, methane-propane, and methane-propane-ethane diffusion flames, which are the main ingredients of LNG, to evaluate its effect on flame formation and combustion products. The variation in combustion products produced by adding hydrogen gradually to diffusion pyrolysis at room temperature and normal pressure conditions was observed experimentally by using a gas analyzer, and the shape of diffusion pyrolysis was observed step by step using a digital camera. The experimental results showed that the production volume of nitrogen oxides tended to increase and became close to linear as hydrogen was added to the diffusion pyrotechnic. This is because the relatively high temperature of heat insulation and fast combustion speed of hydrogen facilitated the production of thermal NOx. On the other hand, CO2 production tended to decrease as hydrogen was added to reduce the overall carbon ratio contained in the mixed diffusion flame of methane, methane-propane, and methane-ethane-propane. This means that the mixed fuel use of LNG-hydrogen in ships may potentially reduce emissions of CO2, a greenhouse gas.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.1
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• pp.35-40
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• 1997

This study was conducted to investigate methane emission under different rice cultural practices in paddy soil (Jeonbug Series, occurring on fluvio-alluvial plain). The rates of application of fresh rice straw were 5,000kg/ha in combination with 110 and 160kg N/ha as chemical fertilizer. The methane emission among the rice cultural practices was in the order of transplanting cultivation, direct seeding on flooded surface and direct seeding on dry paddy field. The average methane flux was $10.27mg/m^2/h$ in direct, seeding on dry paddy field and $24.1mg/m^2/h$ in transplanting cultivation. The diurnal variation of methane emission at heading stage was high from 9 a.m. till 7 p.m. and the methane emission rate was highly correlated with air temperature fluctuation and soil Eh. The seasonal change of methane flux was high from ear formation stage to heading stage.

• 월간낙농육우
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• v.32 no.4
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• pp.108-113
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• 2012

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2019.10a
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• pp.47-47
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• 2019

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.433-436
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• 2005

국내 A군에서 운영중인 한 쓰레기 매립지에서 배출되는 침출수와 주변 지하수를 채취하여 화학분석과 동위원소 분석을 실시하였다. 그리고 생활 쓰레기가 분해되는 과정에서 생성되는 가스들을 채집하여 동위원소 분석을 실시하였다. 유기물 분해로 생성된 이산화탄소는 일차적으로 침출수의 알칼리도를 높이고 이차적으로 일어나는 이산화탄소의 환원작용에 의하여 메탄가스가 형성되었다. 이러한 과정에서 침출수내의 용존무기탄소(DIC)의 탄소 동위원소 조성이 부화되었으며, 아울러 생성된 메탄과의 수소 동위원소 교환반응에 의하여 침출수의 수소 동위원소 조성이 크게 부화되는 특징이 관찰 되었다. 쓰레기장에서 발생되는 혼합가스에서 이산화탄소를 분리하여 탄소 동위원소 조성을 분석해 본 결과 새로운 매립지 보다 오래된 매립지에서 배출되는 이산화탄소의 탄소 동위원소 조성이 부화되는 특징이 관찰되었다.

• Journal of Energy Engineering
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• v.10 no.1
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• pp.49-54
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• 2001

최근 자동차용 청정 연료로서의 이용 가능성으로 주목받는 디메틸에테르를 액상 혼합 반응기에서 직접 합성 가스로부터 합성하였다. 메탄올 함성촉매와 감마알루미나의 혼성촉매를 사용한 결과, $H_2$/CO=1일 때, 메탄올 함성 촉매와 탈수촉매의 비가 8:2인 경우, 가장 높은 메탄옥 환산 생산량을 보였다. 또한 공간속도의 변화에 따른 디메틸에테르, 메탄올, 이산화탄소, 메탄 등 각 생성물에 대한 선택도의 변화는 거의 없이 일정하였다. 메탄옥 합성 반응 촉매만을 사용한 경우, 생성물 중 각 성분의 선택도는 반응가스의 공간속도에 따라 달라졌는데, 반응가스의 공간속도가 작아지면 생성물 중 디메틸에테르의 선택도는 변화가 없었으나, 이산화탄소의 발생량이 많고 메탄올의 생성이 적어졌다. 동일한 반응 조건에서 액상 반응과 시강 반응을 비교한 결과, DME 수율이 액상의 경우가 더 높았다.

• Korean Journal of Microbiology
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• v.48 no.2
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• pp.125-133
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• 2012

Anaerobic digestion is an alternative method to digest food wastes and to produce methane that can be used as a renewable energy source. We investigated bacterial and archaeal community structures in a three-stage methane production process using food wastes with concomitant wastewater treatment. The three-stage methane process is composed of semianaerobic hydrolysis/acidogenic, anaerobic acidogenic, and strictly anaerobic methane production steps in which food wastes are converted methane and carbon dioxide. The microbial diversity was determined by the nucleotide sequences of 16S rRNA gene library and quantitative real-time PCR. The major eubacterial population of the three-stage methane process was belonging to VFA-oxidizing bacteria. The archaeal community consisted mainly of two species of hydrogenotrophic methanogen (Methanoculleus). Family Picrophilaceae (Order Thermoplasmatales) was also observed as a minor population. The predominance of hydrogenotrophic methanogen suggests that the main degradation pathway of this process is different from the classical methane production systems that have the pathway based on acetogenesis. The domination of hydrogenotrophic methanogen (Methanoculleus) may be caused by mesophilic digestion, neutral pH, high concentration of ammonia, short HRT, and interaction with VFA-oxidizing bacteria (Tepidanaerobacter etc.).

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.282-289
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• 2014

BACKGROUND: Methane($CH_4$) is considered as the secondmost potent greenhouse gas after carbon dioxide ($CO_2$). Methanogenesis is an enzyme-mediated multi-step process by methanogens. In the penultimate step, methylated Co-M is reduced by methyl Co-M reductase (MCR) to $CH_4$ involving a nickel-containing cofactor F430. The activity of MCR enzyme is dependent on the F430 and therefore, the bioavailability of Ni to methanogens is expected to influence MCR activity and $CH_4$ production in soil. In this study, different doses of EDTA(Ethylene Diamine Tetraacetic Acid) were applied in flooded soils to evaluate their suppression effect on methane production by chelating Ni of methanogenesis cofactor. METHODS AND RESULTS: EDTA was selected as chelating agents and added into wetland and rice paddy soil at the rates of 0, 25, 50, 75, and $100mmol\;kg^{-1}$ before 4-weeks incubation test. During the incubation, cumulative $CH_4$ production patterns were characterized. At the end of the experiment, soil samples were removed from their jars to analyze total soil Ni and water-soluble Ni content and methanogen abundance. Methane production from 100 mmol application decreased by 55 and 78% in both soils compared to that from 0 mmol. With increasing application rate of EDTA in both soils, water-soluble Ni concentration significantly increased, but total soil Ni and methanogen activities showed negative relationship during incubation test. CONCLUSION: The decrease in methane production with EDTA application was caused by chelating Ni of coenzyme F430 and inhibiting methanogenesis by methyl coenzyme M reductase. Consequently, EDTA application decreased uptake of Ni into methanogen, subsequently inhibited methanogen activities and reduced methane production in flooded soils.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2197-2204
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• 2000

Lignin is a major component of wastewater generated in the chemical processing of wood. Because it is recalcitrant, it inhibits biological treatment of wastewater of pulp manufacturing, especially high concentration of lignin may inhibit the anaerobic digestion. The objective of this study was to evaluate the toxicity of high molecular hardwood lignin (lignosulfonate, MW $\geq$ 20,000) on aceticlastic methanogens in the batch reactors at different temperatures with different sludge concentrations, using anaerobic serum bottles. The hardwood lignin was found to inhibit anaerobic conversion of acetate to methane and carbon dioxide, shown with a long lag-phase before methanogenesis started. The methanogens assumed not to be able to acclimate to the lignin were found to be acclimated slowly in the batch experiments, finally reaching non-toxic levels in which methane production could start. The hardwood lignin was found not to be bacteriocidal but bacteriostatic to aceticlastic methanogens. Hardwood lignin(lignosulfonate) at 1.3, 2.6, and 3.9%(w/w) inhibited the acetateutilizing methanogens of anaerobic digester sludge by 14.5, 17.8, 21.1 days(in noninhibitory condition it took 10 days) to produce the same amount of methane. The inhibitory effect of lignin was examined at temperature ranges of $30^{\circ}C$ to $50^{\circ}C$. When 2.6% of lignin was contained in wastewater, methane production was highest at $30^{\circ}C$ during initial 8 days. At $4^{\circ}C$, methane production rapidly increased after 12 days of digestion, the value became higher than that at $30^{\circ}C$ after 14 days. However, the methane production was completely inhibited during whole digestion period at $50^{\circ}C$. High ratio of lignin concentration to initial anaerobic sludge concentration gave tolerance to the inhibition. In this experiment, high molecular hardwood lignin was not degraded and decolorized.