• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XIII)
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• pp.422-427
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• 2003

Rhodopseudomonas palustris P4 can produce $H_2$ either from CO by water-gas shift reaction or from various sugars by anaerobic fermentation. Fermentative $H_2$ production by P4 is fast, but its yield is relatively low due to the formation of various organic acids. In order to increase $H_2$ production yield from glucose, P4 was investigated for the photo-fermentation of acetate which is a major by-product of fermentative $H_2$ production. Experiments were performed in batch modes using both light-grown and dark-grown cells. When the dark-grown P4 was challenged with light and acetate, $H_2$ was produced with the consumption of acetate after a lag period of 25 h. $H_2$ production was inhibited when a nitrogen source, especially ammonium, is present. When the dark-fermentation broth containing acetate was adopted for photo-fermentation with light-grown cells, $H_2$ production and concomitant acetate consumption occurred without a lag period. The $H_2$ yield was estimated as 2.4 - 2.8 mol $H_2/mol$ acetate and the specific $H_2$ production rate was as 9.8 ml $H_2/g$ cell${\cdot}$h, The fact that a single strain can perform both dark- and light-fermentation gives a great advantage in process development Compared to a one-step dark-fermentation, the combined dark- and light-fermentation can increase the $H_2$ production yield on glucose by two-fold.

• 유기물자원화
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• 제19권3호
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• pp.73-78
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• 2011

혐기성 수소 발효시 pH는 물질 대사 경로와 수소 생성 미생물의 활성에 직접적으로 영향을 미치는 가장 중요한 요소 중 하나로 알려져 있다. 본 연구는 음식폐기물로부터 운전 pH에 따른 혐기성 회분식수소 발효의 영향을 평가하기 위해 수행하였다. 5 N KOH 용액을 이용하여 초기 pH는 8.0으로 고정하였으며, 운전 pH는 4.7~7.0으로 유지하였다. 운전 pH가 낮을수록 지체 시간은 단축되는 것으로 나타났으며, 최대 수소 발생량은 낮게 나타났다. 운전 pH 4.7일 경우에는 지체 시간이 47.9 h으로 가장 길게 나타났으나, 최대 수소 발생량은 534.4 mL로 가장 높게 나타났다. 운전 pH가 증가함에 따라 지체 시간과 최대 수소 발생량은 감소하였다. 운전 pH 7.0일 경우에는 지체 시간이 4.2 h으로 나타났으며, 최대 수소 발생량은 213.8 mL로 나타났다.

• 유기물자원화
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• 제19권1호
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• pp.102-108
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• 2011

혐기성 회분식 반응조를 이용하여 다양한 유기성 폐기물의 에너지화 가능성을 평가하기 위하여 수소발생 특성을 평가하였다. 본 연구에서 채소류는 파, 과일류는 사과, 곡류는 쌀밥 그리고 육류로는 돼지고기를 사용하였다. 파, 사과, 쌀밥 및 돼지고기의 최종 수소 수율은 각각 0.46, 0.47, 0.62 및 $0.05mol\;H_2/mol\;hexose$로 나타났다. 수소 발생율은 파, 사과, 쌀밥 및 돼지고기에서 각각 0.013, 0.021, 0.014 및 $0.005mol\;H_2/mol\;hexose/h$로 평가되었다. 따라서 돼지고기를 제외한 음식폐기물의 혐기성 수소 발효는 재생에너지 생산뿐만 아니라, 유기물의 제거에 효과적인 것으로 나타났다. 휘발성 지방산은 수리학적 체류시간이 증가함에 따라 높게 발생되는 것으로 나타났다. 수소 발효시 산발효 효율은 쌀밥이 75.8%로 가장 높게 나타났으며, 돼지고기는 35.2%로 가장 낮게 나타났다.

• KSBB Journal
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• 제21권6호
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• pp.451-455
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• 2006

본 실험실에서는 음식폐기물을 효율적으로 소화처리하기위해 Pilot 규모 (10톤)의 3단계 메탄 발효 공정을 개발하여 운전하고 있다. 3단계 메탄발효시스템은 반혐기성 가수분해조, 혐기성 산발효조, 혐기성 메탄발효조로 구성되어 있으며, 이 가운데 두 번째 공정인 혐기성 산발효조로부터 알코올발효능이 우수한 균주 KA4를 분리하였다. 세포의 형태는 타원형 모양이며, 크기는 $5.5-6.5{\times}3.5-4.5\;{\mu}m$ 이었고, 26S rDNA D1/D2 rDNA sequence를 분석한 결과를 바탕으로 Saccharomyces cerevisiae KA4로 명명하였다. 이 균주를 YM 배지에서 배양하였을 경우 $30-35^{\circ}C$에서 최대 생장을 보였으며, 배지내의 초기 에탄올 농도가 5% (v/v)까지는 생장에 영향을 받지 않았으나 그 이상에서는 생장에 저해를 받았고 7% 이상에서는 생장하지 못하였다. 한편 초기 50% (w/v)까지의 당 농도에서는 생장이 가능하였으나 잔류 당 농도를 고려할 때 에탄올 발효를 위한 최적 당 농도는 10%이었다. 이 농도의 당을 이용하여 초기 pH4에서 10까지의 넓은 범위에서 에탄올 발효가 가능하였으며 최적 pH는 6이었다 이 때 에탄올 생산량은 7.4%이었으며, 에탄올 생산수율은 2.87 mol EtOH/mol glucose이었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 제17회 워크샵 및 추계학술대회
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• pp.299-306
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• 2005

Anaerobic fermentation of food waste (FW) and waste activated sludge (WAS) for hydrogen production was performed in CSTR (Continuous Stirred tank reactor) under various HRTs and volumetric mixing ratio (V/V) of two substrates, FW and WAS. The specific hydrogen production potential of FW was higher than that of WAS. However, pH drop in the CSTR for hydrogen production from FW was higher than that from WAS. The maintenance of desired pH during fermentative hydrogen production is regarded as the most important operation parameter for the stable hydrogen production. Therefore, when the potential of hydrogen production from FW and better buffer capacity of WAS, the proper mixture of FW and WAS for fermentative hydrogen production were considered as a useful complementary substrate. The maximum yield of specific hydrogen production, 140 mL/g VSS, was found at HRT of 2 day and the volumetric mixing ratio of 20:80 (WAS : FW). The spatial distribution of hydrogen producing bacteria was observed in anaerobic fermentative reactor using fluorescent in situ hybridization (FISH) method.

• 한국미생물·생명공학회지
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• 제24권2호
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• pp.247-253
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• 1996

Changes in microorganisms, enzyme activities and major components of two types of Doenjang prepared with spring Meju and autumn Meju and Kochujang were investigated during 4 months of fermentation. The viable cell counts of aerobic bacteria in Doenjang and Kochujang were increased up to 60 days of fermentation, but viable cell counts of anaerobic bacteria did not show remarkable changes during fermentation. Viable cell count of yeast showed a rapid increase up to 15 days of fermentation in Doenjang and 60 days in Kochujang. It was found that $\alpha$-amylase activity of autumn Meju Doenjang and glucoamylase activity of Kochujang were higher than the other. Acidic and neutral protease showed the highest activity during 15-30 days of fermentation. The pH of Doenjang was increased up to pH 7.0 until 60 days of fermentation, but pH of Kochujang gradually decreased during fermentation. Moisture content of spring Meju Doenjang and Kochujang decreased to 40% during ferme- ntation and reducing sugar content of Kochujang increased up to 15 days of fermentation, but decreased after that.

• 한국수소및신에너지학회논문집
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• 제26권3호
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• pp.199-205
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• 2015

Organic wastes such as food waste (FW), livestock wastewater (LW), and sewage sludge (SWS) can produce hydrogen ($H_2$) by anaerobic acid fermentation. Expecially, FW which has high carbohydrate content produces $H_2$ and short chain fatty acids by indigenous $H_2$ producing microorganisms without adding inoculum, however $H_2$ production rate (HPR) and yield have to be improved to use a commercially available technology. In this study, LW was mixed to FW in different ratios (on chemical oxygen demand (COD) basis) as an auxiliary substrate. The mixture of FW and LW was pretreated at pH 2 using 6 N HCl for 12 h and then fermented at $37^{\circ}C$ for 28 h. HPR of FW, 254 mL $H_2/L/h$, was increased with the addition of LW, however, mixing ratio of LW to FW was reversely related to HPR, exhibiting HPR of 737, 733, 599, and 389 mL $H_2/L/h$ at the ratio of FW:LW=10:1, 10:2, 10:3, and 10:4 on COD basis, respectively. Maximum HPR and $H_2$ production yield of 737 $H_2/L/h$ and 1.74 mol $H_2/mol$ hexoseadded were obtained respectively at the ratio of FW:LW=10:1. Butyrate was the main organic acid produced and propionate was not detected throughout the experiment.

• 한국축산시설환경학회지
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• 제6권2호
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• pp.73-81
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• 2000

A two-phase anaerobic digestion system for the treatment of swine waste was constructed in a commercial hog farm. The digester system was composed of 4 major units; slurry storage pit, acidogenic digester, methanogenic digester and sedimentation pit. A biogas boiler unit was also attached to maintain the digester temperature of 37$^{\circ}C$. Substrate lading was made with 2hr-interval by pumping about 2.1$m^3$ of slurry type swine waste from the slurry pit into the acidogenic digester, which corresponds to hydraulic retention time of 4 days for the acidogenic digester and of 11 days for the methanogenic digester. Digester temperature were well maintained as the set temperature of 37$^{\circ}C$ in the methanogenic digester, while the temperature in the acidogenic digester showed around 34$^{\circ}C$. pH also showed a steady-state results of 7.3 in the acidogenic digester and of 7.6 in the methanogenic digester during the operation period. Average biogas production rate was 0.66$m^3$/$m^3$ digester volume. Reduction rate of total solid and volatile solid were 42.8% and 5.8%, respectively. Total nitrogen and ammonia nitrogen were not reduced during the anaerobic fermentation, however, most of VFAs seemed to be converted to the biogas,. These fermentation performance data may suggest that he newly developed a two-phase anaerobic digester for the swine waste treatment worked so successfully.

• Journal of Microbiology and Biotechnology
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• 제18권3호
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• pp.532-538
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• 2008

For the newly isolated $H_2$-producing chemoheterotrophic bacterium Citrobacter amalonaticus Y19, anaerobic glucose metabolism was studied in batch cultivation at varying initial glucose concentrations (3.5-9.5 g/l). The carbon-mass and energy balances were determined and utilized to analyze the carbon metabolic-pathways network. The analyses revealed (a) variable production of major metabolites ($H_2$, ethanol, acetate, lactate, $CO_2$, and cell mass) depending on initial glucose levels; (b) influence of NADH regeneration on the production of acetate, lactate, and ethanol; and (c) influence of the molar production of ATP on the production of biomass. The results reported in this paper suggest how the carbon metabolic pathway(s) should be designed for optimal Hz production, especially at high glucose concentrations, such as by blocking the carbon flux via lactate dehydrogenase from the pyruvate node.

• 한국수소및신에너지학회논문집
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• 제27권5호
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• pp.510-516
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• 2016

This study examines the effects of linear alkylbenzene sulfonate on hydrogen fermentation of food waste. The hydrogen production rate was similar with different linear alkylbenzen sulfonate (LAS) concentrations. The maximum hydrogen yield increased with increasing LAS concentration. The highest maximum hydrogen yield was $0.550{\pm}0.005mol$ H2/mol hexose at LAS for 5.52 mg/L. But the maximum hydrogen yield decreased above LAS for 11.05 mg/L. The concentration of acetate in control reactor was increased, but it decreased with increasing LAS concentration in other reactors.