• 한국환경보건학회지
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• 제25권3호
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• pp.29-35
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• 1999

Quantity and composition of biogas from semi-continuous anaerobic digestion of straw were obtained experimentally in laboratory scale digesters fed with 1 liter of 5% straw-water mixture and maintained at 35$^{\circ}C$. Experiments were carried out for hydraulic retention time(HRT) of 8, 10 and 15days, respectively. The amount and composition of biogas produced were measured until steady-state was achieved for each run. The amount of biogas and methane percent go through a maximum and decrease continuously towards the steady-state after three times operation of hydraulic retention time(HRT). Methane gas production rates at steady-state increase with the increasing of HRT. Biogas production of 0.45 liter/day with 25% methane, 0.42 liter/day with 33.7% methane and 0.492 liter/day with 31.7% methane were obtained for 8, 10 and 15days of HRT, respectively. The high proportion of soluble carbohydrates present in straw makes the volatile fatty acids to build up within the digester causing a drop in pH that inhibits digestion. Regular control of pH is therefore necessary by adding alkalinity. Reductions in COD increase with increase in HRT. The stratification of plant material within the digester is different from that of manure, and modifications in design and operation of digesters may be necessary if they are fed with plant matter.

• Journal of Microbiology and Biotechnology
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• 제6권1호
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• pp.30-35
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• 1996

Distillery wastewater was used in a thermophilic laboratory-scale two stage anaerobic digester to test the effects of the redox potential of the first acidogenic reactor on the performance of the system. The digester consisted of first a acidogenic reactor and the an upflow anaerobic sludge blanket (UASB) reactor. The digestor was operated at a hydraulic retention time (HRT) of 48 h. Under these conditions, about 90% of the chemical oxygen demand as measured by the chromate method ($COD_{cr}$) was removed with a gas production yield of 0.4 l/g-COD removed. The redox potential of the acidogenic reactor was increased when the reactor was purged with nitrogen gas or agitation speed was increased. The increase in reduction potential was accompanied by an increase in acetate production and a decrease in butyrate formation. A similar trend was observed when a small amount of air was introduced into the acidogenic reactor. It is believed that the hydrogen partial pressure in the acidogenic reactor was decreased by the above mentioned treatments. The possible failure of anaerobic digestion processes due to over-loading could be avoided by the above mentioned treatments.

• 한국물환경학회지
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• 제16권4호
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• pp.541-554
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• 2000

Experimental study of anaerobic digestion process combined with and without the submerged separation membrane was investigated by using laboratory-scale reactor at the hydraulic retention time of 0.5 day and 1.0 day. The removal efficiencies of carbohydrate at the digester without and with membrane were 84.4 to 86.8 % and 99.6 to 99.7 %, respectively, and the methane gas recovery efficiencies were 0.4 to 1.2 % and 12.3 to 28.7 %. According to the measurement by the most probable numbers method. the numbers of various groups of bacteria in the digesters with membrane were enumerated in the following ranges ; acidogens : $1.7{\times}10^9$ to $5.0{\times}10^9MPN/m{\ell}$, homoacetogens : $5.0{\times}10^7$ to $2.4{\times}10^8MPN/m{\ell}$, $H_2$-utilizing methanogens : $1.3{\times}10^7$ to $9.2{\times}10^8MPN/m{\ell}$, and acetate-utilizing methanogens : $2.3{\times}10^6$ to $2.0{\times}10^8MPN/m{\ell}$. The number of methanogens at the digester with membrane increased by approximately $10^2$ to $10^4$ times in comparison with that of the digester without membrane.

• 한국토양비료학회지
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• 제50권4호
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• pp.293-305
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• 2017

This experiment was conducted to evaluate the effect of leachate replacement frequency on solid state anaerobic digestion (SSAD) of dairy manure using 22 L volume lab-scale digesters at mesophilic temperature ($37^{\circ}C$) in batch mode. Three different leachate replacement strategies (no replacement, once every three days, and once every nine days) were applied and three digesters per each treatment were operated for 45 days. Results showed that leachate replacement test unit every nine days resulted in 1.6 times more methane production ($53.8N{\cdot}mL\;g^{-1}{\cdot}VS$) from SSAD compared to test unit every three days ($34.0N{\cdot}mL\;g^{-1}{\cdot}VS$). No leachate replacement strategy applied group showed slightly higher methane production ($56.3N{\cdot}mL\;g^{-1}{\cdot}VS$) than every nine days replaced one. When added the methane production potential of replaced leachate itself to the methane produced from digester, leachate replacement every nine days resulted in quite similar methane production ($56.5N{\cdot}mL\;g^{-1}{\cdot}VS$) to no leachate replacement group. Even though methane production potential of replaced leachate itself added to the methane produced from digester, every three days replacement showed only $34N{\cdot}mL$ methane production per gram of volatile solids. These results suggest that farmers do not need to replace leachate during SSAD of dairy manure and sawdust mixture in order to maximize methane production. If there are any concerns with accumulation of inhibiting substances in the digester, the 9-day cycle leachate replacement is appropriate.

• Asian-Australasian Journal of Animal Sciences
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• 제29권4호
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• pp.586-593
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• 2016

A new methanogen was isolated from an anaerobic digester using pig slurry in South Korea. Only one strain, designated KOR-1, was characterized in detail. Cells of KOR-1 were straight or crooked rods, non-motile, 5 to $15{\mu}m$ long and $0.7{\mu}m$ wide. They stained Gram-positive and produced methane from $H_2+CO_2$ and formate. Strain KOR-1 grew optimally at $38^{\circ}C$. The optimum pH for growth was 7.0. The strain grew at 0.5% to 3.0% NaCl, with optimum growth at 2.5% NaCl. The G+C content of genomic DNA of strain KOR-1 was 41 mol%. The strain tolerated ampicillin, penicillin G, kanamycin and streptomycin but tetracycline inhibited cell growth. A large fragment of the 16S rRNA gene (~1,350 bp) was obtained from the isolate and sequenced. Comparison of 16S rRNA genes revealed that strain KOR-1 is related to Methanobacterium formicicum (98%, sequence similarity), Methanobacterium bryantii (95%) and Methanobacterium ivanovii (93%). Phylogenetic analysis of the deduced mcrA gene sequences confirmed the closest relative as based on mcrA gene sequence analysis was Methanobacterium formicicum strain (97% nucleic acid sequence identity). On the basis of physiological and phylogenetic characteristics, strain KOR-1 is proposed as a new strain within the genus Methanobacterium, Methanobacterium formicicum KOR-1.

• 한국방재학회 논문집
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• 제11권3호
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• pp.237-243
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• 2011

강화되는 방류수 수질기준에 맞추어 하수처리장 개조 방안의 하나로 고농도의 암모니아성 질소를 함유한 반류수를 처리하는 방안이 주장되고 있다. $35^{\circ}C$, $20^{\circ}C$와 $10^{\circ}C$ 조건의 실험실 규모 반응조 운전을 통하여 경제적인 질소 제거 방법인 아질산화 반응 유도하였다. $20^{\circ}C$ 이상의 온도에서는 안정적인 아질산화 반응을 유도 할 수 있었으나, $10^{\circ}C$ 저온 조건에서는 완전 질산화 반응이 유도 되었다. 이는 온도의 영향을 받아 SRT가 길어져 완전 질산화 반응이 유도된 것으로 사료된다. 온도에 따라 아질산화 반응에 요구되는 SRT가 변화하는 것으로 볼 때, 온도와 SRT는 아질산화 반응에 중요한 인자로 판단된다. 또한 $20^{\circ}C$ 이상의 조건에서 암모니아성 질소 제거 반응과 아질산화 반응을 유도하는 것이 유리 한 것으로 나타났다. 본 논문에서 제시한 결과는 아질산화 반응을하수처리장에 적용할 때 중요한 기초 자료로 사용될 수 있을 것이다.

• 연구논문집
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• 통권30호
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• pp.33-42
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• 2000

We must stabilize quickly increasing waste matters in urban life and livestock industry. Biogas including landfill gas and digester gas is byproduct of anaerobic decomposition of organic waste matter and contains 40%-70% methane, which can be used for energy purposes. Utilization of biogas reduce the emission of methane into the atmosphere to minimize greenhouse effect and the carbon dioxide (CO2) emitted when biogas is converted to energy has been taken out of the atmosphere by growing plant. Recently, bioenergy is world-widely noticeable as all contributing to the greenhouse effect. This paper presents development process of a biogas engine for cogeneration system and results of application to digester gas and landfill gas in site. The biogas engine is a dual fuel engine operated on biogas with a diesel pilot. At present, the engine can substitute biogas for diesel fuel up to 85%. but it can be said that there is a possibility of improvement in performance.

• 한국환경과학회지
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• 제28권2호
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• pp.203-209
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• 2019

Organic wastewater generated from polyester manufacturing processes was selected from H company to investigate the feasibility of anaerobic digestion that produces gases including methane. Bio Methane Potential (BMP) tests were conducted to measure the gas production and methane concentration for 7 process wastewater and 2 kinds of sludges from the H company. Also, along with monitoring pH and alkalinity during the anaerobic digestion process, the concentrations of COD and 1,4-dioxane were measured with 4 different operating conditions for N Emulsion (NE) and Ethylene Glycol (EG) wastewater. The BMP tests showed that 65% of methane was produced from NE and EG wastewater. This suggests that the organic wastewater from H company can be effectively treated by an anaerobic digester by which more than 90% of COD was removed.

• 한국환경과학회지
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• 제1권2호
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• pp.125-136
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• 1992

Digestion of a municipal wastewater sludge by the anaerobic sequencing batch reactor (ASBR) was investigated to evaluate the performance of the ASBR process at a critical condition of high-solids-content fined. The reactors were operated at an HRT of 10 days with an equivalent loading rate of 0.8-1.5 gVS/L/d at 35$^{\circ}C$ The main conclusions drawn from this study were as follows: 1. Digestion of a municipal wastewater sludge was possible using the ASBR in spite of high concentration of settleable solids in the sludge. The ASBRS with 3- and 4-day cycle period showed almost identical high digestion performances. 2. No adverse effect on digestion stability was observed In the ASBRS in spite of withdrawal and replenishment of 30% or 40% of liquid contents. A conventional anaerobic digester could be easily converted to the ASBR without any stability problem. 3. Flotation thickening occurred in thicken step of the ASBRS throughout steady state, and floating bed volume at the end of thicken period occupied about 70% of the working volume of the reactor Efficiency of flotation thickening in the ASBRS could be comparable to that of additional gravity thickening of a completely mixed digester. 4. Solids were accumulated rapidly in the ASBR during start-up period. Solids concentrations in the ASBRS were 2.6 times higher than that in the completely mixed control reactor at steady state. Dehydrogenase activity had a strong correlation with the solids concentration. Dehydrogenase activity of the digested flu형e in the ASBR was 2.9 times higher than that of the flu형e in the control reactor, and about 25 times higher than that of the subnatant in the ASBR. 5. Remarkable increase in equivalent gas production of 52% was observed at the ASBRS compared with the control reactor in spite of similar quality of clarified effluent from the ASBRS and control reactor. The increase in gas production from the ASBRS was believed to be combined results of accumulation of microorganisms, higher driving force applied, and additional long-term degradation of organics continuously accumulated.

• 대한환경공학회지
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• 제33권7호
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• pp.516-522
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• 2011

국내에서 운영중인 혐기성 소화조의 가장 큰 문제점은 낮은 소화효율이며, 이에 대한 원인은 낮은 유기물 투입농도, 소화조내의 낮은 교반 효율, 잉여슬러지의 난분해성 등이다. 본 연구에서는 혐기성 소화설비의 효율성을 높이기 위하여 기존의 혐기성 소화 시스템에 농축 및 교반, 오존 가용화 설비를 설치하고, 기존의 2단 소화조에서 단단소화조로 개선함으로서 소화효율 및 바이오가스의 발생량을 증대 시키고자 하였다. 이러한 개선을 통하여 농축시스템의 슬러지 농도는 2.6배 향상되었음을 확인하였으며, 농축효율은 3.0배 증가한 것으로 나타났다. 또한, 기계식 교반으로 사공간이 줄어들었음을 확인하였으며, 혐기성 소화조 내 소화가스 발생량도 평균 $193.8m^3$/일에서 평균 $386.0m^3$/일로 향상된 것을 확인하였다. 소화효율은 평균 47.6%에서 54.6%로 향상되어진 것으로 나타났으며, VS제거당 소화가스 발생량은 평균 $0.30Nm^3/kg$ VS removal에서 $0.42Nm^3/kg$ VS removal로 증대되어진 것으로 나타났다.