• Korean Journal of Environmental Agriculture
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• v.17 no.3
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• pp.234-238
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• 1998

Anaerobic degradation characteristics of dewatered liquid of household food waste including methane conversion efficiency and degradation kinetics were studied in an anaerobic batch reactor of 5 L volume. The ultimate methane production for dewatered liquid of household food waste tested was over 0.31L $CH_4/L{\cdot}dewatered$ liquid of household food waste. The kinetic constant of dewatered liquid of household food waste tested was $0.223d^{-1}/L$. The kinetic behavior of anaerobic degradation was described as a first order series reaction. The determinant of rate-limiting step(DR) that is balanced out from the rates of reaction steps was defined by the logarithmic difference of the maximum acidification rate and the maximum methanation rate. Anaerobic degradation characteristics of organic materials were evaluated by the value of DR. The DR of dewatered liquid of household food waste tested was 1.17.

• Journal of Korean Society of Water and Wastewater
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• v.8 no.1
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• pp.27-33
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• 1994

With the rapid industrialization, an ever-increasing quantity and kind of new organic compounds pose environmental problems due to their toxicity and physiological effect. However, research on the biodegradation of these compounds under anaerobic condition is very limited inspite of its efficiency and economical advantage. In this research, the pH effect on the ring cleavage of phenol under anaerobic condition was investigated, and the theory of phase separation was applied to the degradation of phenol for investigating the role of acidogenic bacteria. Results, obtained from biochemical methane potential(BMP) assay for 15.5 days of incubation, showed that acidic condition was more desirable for phenol degradation than alkaline condition. By both unacclimated methanogenic granular sludge and two mixed cultures, phenol was completely removed within six weeks of incubation with a gas conversion rate of over 86% of theoretical one. However, phenol was not degraded by unacclimated acidogenic culture, and thus it is considered as a syntrophic substrate. In case of phase separated biochemical methane potential(PSBMP) assay, in which acidogenic and methanogenic culture were seeded separately and consecutively, those that had been subjected to normal acidogens for 3 to 4 weeks showed higher gas production than those seeded with sterile or frozen culture.

• Journal of the Korean Wood Science and Technology
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• v.14 no.3
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• pp.43-46
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• 1986

A stainless steel autoclave reactor, which is the property of Pacific Northwest Laboratories(PNL) and located in PNL, was acted for pyrolysis and gasification of sawdust, ricestraw, and ricehusk. The initial reaction temperature of this reactor was 300$^{\circ}C$, and up to 500$^{\circ}C$ to complete pyrolysis and gasification reaction. The maximum exerted pressure on this reactor was 800 psig. In order to examine the effect of catalyst on reaction temperature, $K_2CO_3$, and nickel/alkali carbonate catalyst mixture were also used. The experimental results obtained with this reactor indicated that good yields of methane-rich gas(exceeding 40% methane) can be produced. The product gas mixtures were also identified to be CO. $CO_2$, $C_2H_4$, and $CH_3CHO$ etc. by Gas Chromatography and Mass Spectrometer.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2221-2226
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• 2008

The objective of this paper is to describe the experimental and numerical investigation of the analysis of the heat transfer in a solar chemical reactor. These are compared about methane steam reforming process in the solar chemical reactor which was a volumetric absorber consisting of honeycomb and a multilayered catalyst supports. With this high operating temperature, convective heat loss, thermal fracture are important features for designing SCR. In order to estimate the system performance and to design the actual solar reactor with various conditions, CFD analysis was used in this study. The nickel oxide porous metal is inserted inside the solar chemical reactor to increase the conversion rate of the reforming reaction. Simulation has been carried out based on the experimental data. According to the simulation results, the optimum methane-steam mole ratio and thickness and numbers of catalyst supports were obtained.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.6
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• pp.601-607
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• 2019

Ammonia would be formed in natural gas containing small amount of nitrogen reforming process in the process natural gas, which might damage the Pt catalyst and Prox catalyst. In the article, the effect of nitrogen contents on the formation of ammonia in the reforming process has been studied. In the experiments, Ru based and Ni based catalysts were used and the concentration of ammonia in the reformate gas at various gas hourly space velocity was measured. Experimental result shows that relatively higher ammonia concentration was measured with Ru based catalyst than with Ni based catalyst. It also shows that the concentration of ammonia increased rapidly after most of the methane converted into hydrogen. Based on the experimental results to reduce ammonia concentration it might be better to finish methane conversion at the exit position of the reforming reactor to minimize the contact time of catalyst and nitrogen with high concentration of hydrogen.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.2
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• pp.111-118
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• 2019

Greenhouse gas emissions have a profound effect on global warming. Various environmental regulations have been introduced to reduce the emissions. The largest amount of greenhouse gases, including carbon dioxide, is produced in the steel industry. To decrease carbon dioxide emission, hydrogen-based iron oxide reduction, which can replace carbon-based reduction has received a great attention. Iron production generates various by-product gases, such as cokes oven gas (COG), blast furnace gas (BFG), and Linz-Donawitz gas (LDG). In particular, COG, due to its high concentrations of hydrogen and methane, can be reformed to become a major source of hydrogen for reducing iron oxide. Nevertheless, continuous COG cannot be supplied under actual operation condition of steel industry. To solve this problem, this study proposed to use two alternative COG-based fuel mixtures; one with natural gas and the other with biogas. Reforming study on two types of mixed gas were carried out to evaluate catalyst performance under a variety of operating conditions. In addition, methane conversion and product composition were investigated both theoretically and experimentally.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.6
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• pp.456-459
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• 2000

A pilot scale experiment was performed for a year to develop a two-phase anaerobic process for piggery wastewater treatment (COD: 6,000mg/L, BOD: 4,000mg/L, SS: 500mg/L, pH 8.4, alkalinity 6,000mg/L). The acidogenic reactor had a total volume of 3㎥, and the methanogenic reactor, an anaerobic up-flow sludge filter, combining a filter and a sludge bed, was also of total volume 3㎥(1.5㎥ of upper packing material). Temperatures of the acidogenic and methanogenic reactors kept at 20$^{\circ}C$ and 35$^{\circ}C$, respectively. When the pH of the acidogenic reactor was controlled at 6.0-7.0 with HCl, the COD removal efficiency increased from 50 to 80% over a period of six months, and as a result, the COD of the final effluent fell in the range of 1,000-1,500 mg/L. BOD removal efficiency over the same period was above 90%, and 300 to 400 mg/L was maintained in the final effluent. The average SS in the final effluent was 270 mg/L. The methane production was 0.32㎥ CH$_4$/kg COD(sub)removed and methane content of the methanogenic reactor was high value at 80-90%. When the pH of the acidogenic reactor was not controlled over the final two months, the pH reached 8.2 and acid conversion decreased compared with that of pH controlled, while COD removal was similar to the pH controlled operation. Without pH control, the methane content in the gas from methanogenic reactor improved to 90%, compared to 80% with pH control.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.4
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• pp.534-540
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• 2003

This study was conducted to investigate the effect of supplementation of galacto-oligosaccharides (GOS) on methane emission, nutrient digestibility, energy utilization and blood metabolites by Holstein cows fed silages. In two sequential digestion and respiratory trials, two non-lactating Holstein cows were arranged to a balanced incomplete block design. Experimental diets consisted of two silage types; orchardgrass (Dactylis glomerata L.) based silage (OS), mixed silage (orchardgrass based silage and alfalfa (Medicago sativa L.) silage) (MS), while two GOS levels were without supplementation (0) and 2% of dry matter intake supplementation (2). Four combination diets were OS-0, OS-2, MS-0 and MS-2. Significant effects of silage types and GOS supplementation levels were not observed for DM and OM intake. Whereas the digestibility of OM, NDF and ADF was significantly (p<0.05) higher in cows fed OS with and without GOS compared cows fed MS diets. As percentage of GE intake, fecal energy loss for OS diets was significantly (p<0.05) declined than for MS diets. In contrast, cows fed MS diets had lower (p<0.05) urine energy loss as a proportion of GE intake compared to OS diets. Energy loss as CH4 and heat production was numerically increased when cows fed both OS and MS with GOS supplementation. Compared to OS, CH4 emission in cows fed MS was numerically decreased by 10.8 %. Methane conversion ratio (energy loss as CH4 per unit of GE intake) for OS-0, OS-2, MS-0 and MS-2 were 7.1, 7.2, 6.8 and 7.0, respectively. Plasma of glucose and urea-N concentration were significantly (p<0.05) elevated from 1 h to 6 h after feeding, otherwise total protein in plasma was declined (p<0.01) at 6 after feeding.

• Applied Chemistry for Engineering
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• v.8 no.4
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• pp.685-693
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• 1997

We have studied the reforming of carbon dioxide with methane over various supported nickel catalysts. The nickel supported on natural zeolite showed the highest activity and the nickel on acidic support showed higher activity and slow deactivation compared to nickel on basic support. The activity of nickel on natural zeolite increased with increasing loading ratio and showed almost constant activity above 10wt.% loading of nickel. The conversion and yield of products were affected by the mole ratio of reactants and the highest yields of CO and $H_2$ were obtained at $CH_4/CO_2=1$. The deactivation of catalyst was caused by deposition of coke which was formed by the decomposition of methane. The shape of coke was shown to be whisker tripe carbon, and it brought out the slow deactivation of catalyst.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.3
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• pp.221-226
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• 2015

Ru catalysts supported on $CeO_2$ were synthesized by an impregnation method and characterized by numerous analytical techniques including X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). Upon utilization of these catalysts for methane dry reforming with a $CH_4/CO_2$ ratio of 1:1 at different temperatures ranging from 550 to $750^{\circ}C$, the $Ru/CeO_2$ catalysts have shown to be active. In particular, Ru(0.55wt%) supported on $CeO_2$ (1) prepared by a hydrothermal method exhibited excellent activity with the conversion of > 75% at $750^{\circ}C$. In addition, the catalyst also proved to be highly stable for at least 47 h without catalyst deactivation under the dry reforming conditions.