• Journal of environmental and Sanitary engineering
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• v.12 no.3
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• pp.139-147
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• 1997

펄프폐수 내에 존재하는 대표적인 수지 구성성분의 일종인 wood resin 화합물이 메탄생성균에 미치는 독성을 평가하기 위한 회분식 독성실험을 수행하였다. 수지는 극성용매로 추출가능한 몇몇 wood 구성성분의 혼합물로서 수지의 주요 구성성분은 긴 사슬 휘발성유기산, terpenes, resin acids, 리그난과 극성 페놀류들이다. 메탄생성균의 독성실험은 $30^{\circ}C$에서 표준회분식 실험방법을 채택하였고 식종물질로서는 입상슬러지를 사용하였다. 극성페놀의 한 종류인 4-hydroxystilbene가 가장 높은 독성을 나타내었으며, 50% 저해를 일으키는 농도는 $20mg/\ell$이었다. Resin acid와 휘발성 terpene 역시 메탄생성균에 독성을 나타내었으며, 50% 독성을 일으키는 농도는 $43{\;}~{\;}330mg/\ell$이었다. 반면에 triterpenes은 1,000 to $1,300{\;}mg/\ell$의 상대적으로 높은 농도에서도 메탄생성균에 독성을 일으키지 않았다. 따라서 wood resin의 구성성분이 몇몇 펄프폐수의 혐기성 처리에 있어서 독성을 일으키는 주요물질이었다.

• 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.

• Journal of Environmental Health Sciences
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• v.24 no.1
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• pp.70-79
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• 1998

본 실험의 목적은 다양한 펄프제조 조건과 여러 형태의 리그노 셀루로우스 성분이 펄프폐수의 혐기성 생분해에 미치는 영향을 규명하는 것이다. 실험에 사용된 폐수는 일반적으로 펄프 제조시에 발생되는 폐수를 대상으로 하였으며, 펄프제조 조건은 TMP공정과 소다 펄프공정을 적용하였다. 혐기성 생분해 가능성 시험 및 독성실험은 $35\pm 2\circ$C의 중온상태에서 입상슬러지를 식종물질로 사용한 회분식 반응조를 이용하였다. TMP공정의 배출되는 폐수는 산으로의 전환율이 총 COD기준으로 68-87%로 매우 높은 혐기성 생분해 가능성을 보였다. 그리고 TMP공정폐수는 일반적으로 제지폐수 처리시 독성농도라고 알려진 농도에서도 메탄생성균에 독성을 주지 않았고, 또한 COD 10g/l의 농도에서도 처리에 저해가 일어나지 않았다. 반면에, 알카리성 상태에서 준비된 펄프폐수의 경우는 생분해성이 매우 낮아서 대략 50%정도의 산전환율을 보였으며, 메탄생성균에 상당한 저해를 주었다. 메턴생성균의 활성도에 50%저해를 주는 농도는 2.1~5.4 gCOD/l였다. 알카리성 펄프폐수의 독성에 대한 추가 실험결과 펄프내 wood resin이 산이나 중성 pH부근에서는 잘 용해가 되지 않고 알카리성 상태에서 쉽게 용해되어 메탄생성균에 저해를 나타내는 것으로 밝혀졌다. 따라서 펄프제조시 나무성분이 알카리성분과 접촉할 경우 후속하는 혐기성 처리공정의 메탄생성균에 심각한 저해를 줄 수 있다.

• KSBB Journal
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• v.20 no.6
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• pp.431-437
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• 2005

Molecular methods were employed to investigate microorganisms in a thermophilic continuous stirred tank reactor(CSTR) used for continuous $H_2$ production. The reactor was inoculated with heat-treated anaerobic sludge and fed with a glucose-based medium. Denaturing gradient gel electrophoresis showed dynamic changes of bacterial populations in the reactor during 43 days of operation. Gas composition was constant from approximately 14 days but population shift still occurred. Populations affiliated with Fervidobactrium gondwanens and Thermoanaerobacterium thermosaccharolyticum were dominant on 21 and 41 days, respectively. Keeping pH of the medium at 5.0 could suppress methanogenic activity that was detected during initial operation period. $CH_4$ and mcrA detected in the samples obtained from the reactor or inoculum suggested the heat treatment condition employed in this study is not enough to remove methanogens in the inoculum. PCR using primer sets specific to 4 main orders of methanogens suggested that major $H_2$-consuming methanogens in the CSTR belong to the order Methanobacteriales.

• 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.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.532-535
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• 2000

Optical microscope, SEM and fluorescent microscope were used for qualitative and morphological studies of the attachment bacteria on PE substratum under anaerobic condition. The observation of optical microscopic has demonstrated that the initial attachment of bacteria began in crevices of surface. In SEM photographs, shape and structure of biofilm could be observed, but bacteria species and methanogens was not identified. A large number of methanogenic bacteria were showed on the surface of PE substratum by fluorescence under 480nm of radiation. It was estimated that methanogenic bacteria was related to initial attachment of bacteria under anaerobic condition.

• Korean Journal of Microbiology
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• v.52 no.2
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• pp.157-165
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• 2016

Under flooded rice fields, methanogens produce methane which comes out through rice stalks, thus rice fields are known as one of the anthropogenic sources of atmospheric methane. Studies have shown that use of manure increases amount of methane emission from rice. To investigate mechanisms by which manure boosts methane emission, comparative soil metagenomics between inorganically (NPK) and pig manure fertilized paddy soils (PIG) were conducted. Results from taxonomy analysis showed that more abundant methanogens, methanotrophs, methylotrophs, and acetogens were found in PIG than in NPK. In addition, BLAST results indicated more abundant carbohydrate mabolisetm functional genes in PIG. Among the methane metabolism related genes, PIG sample showed higher abundance of methyl-coenzyme M reductase (mcrB/mcrD/mcrG) and trimethylamine-corrinoid protein Co-methyltransferase (mttB) genes. In contrast, genes that down regulate methane emission, such as trimethylamine monooxygenase (tmm) and phosphoserine/homoserine phosphotransferase (thrH), were observed more in NPK sample. In addition, more methanotrophic genes (pmoB/amoB/mxaJ), were found more abundant in PIG sample. Identifying key genes related to methane emission and methane oxidation may provide fundamental information regarding to mechanisms by which use of manure boosts methane emission from rice. The study presented here characterized molecular variation in rice paddy, introduced by the use of pig manure.

• Journal of the Korea Organic Resources Recycling Association
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• v.27 no.2
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• pp.41-49
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• 2019

Livestock manure is a significant source for greenhouse gas (GHG) emission, and a huge amount of GHG emission is generated during its storage. In the present work, lowering temperature was attempted to mitigate methane ($CH_4$) emission from cattle manure (CM) with high solid content. CM was stored for 60 d at $15-35^{\circ}C$ ($5^{\circ}C$ interval). $CH_4$ emission reached $63.6{\pm}3.6kg\;CO_2\;eq./ton\;CM$ at $35^{\circ}C$, which was reduced to $51.6{\pm}1.8$, $24.1{\pm}4.4$, $14.9{\pm}0.5$, and $3.7{\pm}0.1kg\;CO_2\;eq./ton\;CM$ at 30, 25, 20, and $15^{\circ}C$, respectively. After storage, 30% of COD reduction was observed in the CM stored at $35^{\circ}C$, while the COD removal decreased to only 6% at $15^{\circ}C$. It was found that only 3-11% of COD removal was done by anaerobic process, while the rest of COD removal was done by aerobic biological process. Methanobrevibacter and Methanolobus were found to be the dominant species in the CM, and the dominance of Methanolobus psychrophilus increased at lower storage temperature. Specific methanogenic activity test results showed that the inhibition by low temperature was temporal.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.3
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• pp.75-82
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• 2008

Two UASB reactors were operated to investigate the effect of high concentration of sulfate on anaerobic digestion of propionate using an upflow anaerobic sludge blanket (UASB) reactor. An organic loading rate of $1.2kg\;COD/m^3{\cdot}d$ and a hydraulic retention time of 1.6 d were maintained during this study. In the absence of sulfate, the UASB reactor achieved about 95% removal of chemical oxygen demand whereas in the presence of $2,000\;SO_4^{2-}mg/L$, the COD removal rate decreased to 83% due probably to the inhibition of dissolved sulfide inhibition. Interactions between the methane producing bacteria (MPB) and sulfate reducing bacteria (SRB) were measured to investigate the competition between MPB and SRB. The MPB consumed average 58% of the available electron donors at $COD/SO_4^{2-}$ ratio of 1. Propionate was consumed mainly by SRB, converting sulfate into sulfide and suppressing the methane production. The specific methanogenic activity (SMA) using acetate and propionate increased as microorganism acclimated to the substrate.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.2
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• pp.66-75
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• 2012

The objective of this study was to assess the effects of methanogenic bacteria-activated leachate recirculation method for enhancing waste stabilization and landfill gas production from a solid waste landfill. To simulate a conventional landfill (Lys-A), a landfill recirculated only fresh leachate (Lys-B), and two landfills recirculated leachate after pretreating with ASBR (Lys-C and Lys-D), four lysimeters were operated over a period of 4 years. Lys-D was recirculated two times of pretreated leachate volume than that of Lys-C. In the case of the landfill recirculated only fresh leachate and the landfill recirculated leachate after pretreating with ASBR, methane productions were increased until about 600 days, but there were not effect of leachate recirculation for enhancing methane production after about 600 days. It was assumed that leachate recirculation into fewer biodegradable organic wastes had not effect to enhance landfill gas production. Lys-C and Lys-D showed the highest performance for enhancing cumulative methane yield as well as acceleration waste stabilization. In cumulative methane yield, Lys-C (35.51 mL $CH_4/g$ VS) and Lys-D (36.12 mL $CH_4/g$ VS) were much higher than Lys-A (28.37 mL $CH_4/g$ VS) and Lys-B (30.07 mL $CH_4/g$ VS). In case of between Lys-B and Lys-C with the same recirculation rate, COD concentration in Lys-C was more rapidly decreased compared with that in Lys-B. This was attributed to the presence of methanogenic bacteria as well as dilution of inhibitory substances by the methanogenic bacteria-activated leachate recirculation. Therefore, the landfill recirculated leachate after pretreating with ASBR was found to be the most appropriate operating techniques for enhancing waste stabilization and landfill gas production.