• 신재생에너지
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• 제9권1호
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• pp.25-32
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• 2013

It is indispensable to increase the conversion rate of a reducing sugars such as pentose and hexose derived from cellulosic wastes for a highly efficient bioethanol fermentation from food wastes. The saccharification liquid from cellulosic substrates such as vegetable food wastes contained lots of hexose like glucose and pentose like xylose. Since Saccharomyces-based yeasts could not convert xylose to bioethanol, Pichia stipitis which could directly ferment xylose to ethanol was chosen. After selecting Saccharomyces coreanus and P. stipitis, fermentation characteristics by mixture of two yeasts were investigated. As a result, it was verified the production of ethanol was enhanced by the co-fermentation, although there were somewhat differences between the fermentation characteristics by the aeration methods. Moreover, the consumption of pentose, hexose and disaccharide was obviously observed, and aeration in the process of fermentation seemed to stimulate the activity of P. stipitis.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.179.1-179.1
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• 2011

Pretreatment of cellulosic biomass is necessary before enzymatic saccharification and fermentation. The objective of this study was to evaluate the effect of combined aqueous ammonia-dilute sulfuric acid treatment on cellulosic biomass. Miscanthus was pretreated using aqueous ammonia and dilute sulfuric acid solution under high temperature and pressure conditions to be converted into bioethanol. Aqueous ammonia treatment was performed with 15 %(w/w) ammonia solution at $150^{\circ}C$ of reaction temperature and 20 minutes of reaction time. And then, dilute sulfuric acid treatment was performed with 1.0 %(w/w) sulfuric acid solution at $150^{\circ}C$ of reaction temperature and 10 minutes of reaction time. The compositional variations of this combined aqueous ammonia-dilute sulfuric acid treatment resulted in 68.0 % of cellulose recovery and 95.7 % of hemicellulose, 81.3 % of lignin, 89.1 % of ash removal respectively. The enzymatic digestibility of 90.5 % was recorded in the combined pretreated Miscanthus sample and it was 14.7 times higher than the untreated sample. The ethanol yield in the Simultaneous Saccharification and Fermentation was 90.4 % of maximum theoretical yield based on cellulose content of the combined pretreated sample and it was about 98 % compared to the ${\alpha}$-cellulose ethanol yield.

• Journal of Plant Biotechnology
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• 제34권2호
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• pp.111-118
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• 2007

가속도가 붙은 지구온난화 문제와 수 십년 이내로 예상되는 화석연료의 고갈은 지속가능하면서도 환경친화적인 새로운 형태의 에너지 출현을 필요로 하고 있다. 이러한 추세에 맞추어 태양광, 조력, 지열, 풍력, 수소 에너지와 더불어 바이오에너지가 대체에너지로서 주목받고 있다. 바이오에너지는 태양에너지를 유기물로 변환하는 식물을 재료로 하여 바이오 에탄올이나 바이오디젤 등을 생산하여 사용하는 것으로 대체 에너지가 갖춰야 할 조건을 두루 갖춘 최적의 신재생에너지로 고려되고 있다. 하지만 바이오에너지가 진정한 의미에서의 환경친화적이면서 지속가능성을 갖추기 위해서는 아직 기술적으로 해결해야할 문제점들이 많다. 최근 미국에서 바이오에탄올 생산을 위한 옥수수 소비량이 늘어 곡물 및 사료 가격의 급등 현상으로 이어지고 있다. 또한 이러한 현상은 개발도상국 식량자원의 선진국 유입 등으로 빈곤의 심화 등이 새로운 문제점으로 지적되고 있다. 따라서 곡물이 아닌 비식용 부위를 이용한 에탄올 생산이 대안으로 여겨지고 있는 바 셀룰로스 에탄올은 이러한 문제점을 극복할 수 있는 대체에너지로서 자리매김하고 있다. 셀룰로스 바이오에탄올은 사람 등의 동물이 소화하지 못하는 바이오매스의 대부분을 차지하는 식물 세포벽을 곰팡이 등에서 분리한 효소로 분해한 후 여기서 생성되는 당을 발효과정을 통해 생산되는 에탄올로서 전술한 바와 같은 문제점을 해결할 수 있는 유망한 대안 에너지로 고려되고 있다.

• KSBB Journal
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• 제31권1호
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• pp.73-78
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• 2016

The aim of this study attempted to verify the possibility of bioethanol production using wasted medium density fiberboard (wMDF). In order to produce bioethanol from wood cellulosic materials must be carried out the process of pretreatment, saccharification, fermentation and distillation. First, the wMDF was pretreated using sodium chlorite and pretreated wMDF was prepared to 8% slurry and then slurry was saccharified with the commercial enzyme (Cellic CTec3). The fermentable sugar and pH of saccharified substrate were about 5.5% glucose and 4.4, respectively. Herein we compared the results of ethanol yield according to the nutrients added or without addition to increase ethanol yield. Ethanol fermentation was finished in about 24 hours, but it was delayed in experimental group without nutrients. Ethanol content and fermentation ratio of the final fermented mash prepared by utilizing jar fermenter was 25.40 g/L and 86.64%, respectively. At this time, the maximum ethanol productivity was confirmed as 1.78 g/Lh (ethanol content 21.38 g/L, 12 h), and the overall ethanol productivity was 1.05 g/Lh (ethanol content 25.27 g/L, 24 h). Using fermented liquid we could produced bioethanol 95.37% by continuous distillator packed with copper element in laboratory scale. These results show that wMDF has a potential valuable for bioethanol production.

• 한국작물학회지
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• 제58권1호
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• pp.71-77
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• 2013

본 연구는 바이오에탄올 생산용 작물 선발을 위해 국내재배 가능한 일년생 작물중에서 바이오매스 생산량이 우수한 수수-수단그래스 교잡종에 대한 바이오에탄올 생산성을 조사하였으며 그 결과는 다음과 같다. 1. 총 11 품종의 수수-수단그래스 교잡종 대한 화학적 특성 검증 결과 셀룰로오스 함량은 Green Star 품종이 가장 높았으며 발효율 검정을 위해 Green Star, Revolution, KF429 그리고 SS504 4품종을 선발하였다. 2. 선발된 4품종으로부터 발효 당을 추출하기 위해 시료와 1 M NaOH 용매를 1:14의 비율로 혼합하고 $150^{\circ}C$에서 30분간 전처리하였을 때 시료내 셀룰로오스 함량은 55%이상 이였으며, 발효 저해 작용을 하는 리그닌 및 회분 함량은 65%이상 제거 되었다. 3. 전처리물의 당화율 검정을 위해 celli CTEC II 효소 30 FPU/g-cellulose를 사용하였으며 4품종의 당화율은 평균 86%이었다. 4. 수수-수단그래스 교잡종의 발효율 검정은 동시당화발효(SSF)방법으로 수행하였으며 발효균주로는 Saccharomysis cerevisiae CHY1011를 사용하였고, 결과적으로 Green Star의 발효율이 92.4%로 가장 높았으며 에탄올 생산량은 6,206 L/ha임을 확인하였다.

• Journal of Forest and Environmental Science
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• 제27권3호
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• pp.183-194
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• 2011

This study reviewed on the research trend of sources and utilization of the byproducts(Lignin) from bioethanol production process with lignocellulosic biomass such as wood, agri-processing by-products(corn fiber, sugarcane bagasse etc.) and energy crops(switch grass, poplar, Miscanthus etc.). During biochemical conversion process, only Cellulose and hemicellulosic fractions are converted into fermentable sugar, but lignin which represents the third largest fraction of lignocellulosic biomass is not convertible into fermentable sugars. It is therefore extremely important to recover and convert biomass-derived Lignin into high-value products to maintain economic competitiveness of cellulosic ethanol processes. It was introduced that lignin types and characteristics were different from various isolation methods and biomass sources. Also utilization and potentiality for market of those were discussed.

• 유기물자원화
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• 제16권1호
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• pp.79-88
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• 2008

지구온난화에 따른 대체연료의 하나로 바이오에탄올의 생산이 증대되면서 곡물가격 상승과 같은 문제를 야기하고 있다. 차세대 바이오에탄올의 원료로서 목질계 바이오매스는 큰 잠재성에도 불구하고 높은 생산단가로 인하여 상업화 되지는 않고 있다. 생산단가의 절감을 위해 필요한 핵심기술은 가수분해율을 높이고 단당의 회수율을 높이는 것으로 전체 바이오에탄올 생산공정에서 열화학적 전처리이다. 본 연구에서는 목질계 바이오에탄올 제조공정에서의 열화학적 전처리에 대하여 소개하고 극복해야 할 문제들에 대하여 제시하고자 한다. 산, 알칼리, 열수, 용매, 암모니아, 산소 등을 첨가하는 전처리는 리그닌과 헤미셀룰로오스를 제거하고 셀룰로오스의 결정성을 감소시킨다. 이러한 전처리 방식들은 침엽수, 활엽수, 곡식의 줄기 등 목질계 원료에 따라 최적의 처리 조건들이 확립되어져야 한다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2011년도 춘계학술발표회 논문집
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• pp.81-91
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• 2011

Current fuel ethanol research and development deals with process engineering trends for improving biotechnological production of ethanol. Recently, a large amount of studies regarding the utilization of lignocellulosic biomass as a good feedstock for producing fuel ethanol is being carried out worldwide. The plant biomass is mainly composed of cellulose, hemicellulose and lignin. The main challenge in the conversion of biomass into ethanol is the complex, rigid and harsh structures which require efficient process and cost effective to break down. The isolation of microorganisms is one of the means for obtaining enzymes with properties suitable for industrial applications. For these reasons, crude cultures containing cellulosic biomass degrading microorganisms were isolated from rice field soil, cow farm soil and rotten rice straw from cow farm. Carboxymethyl cellulose (CMC), xylan and Avicel (microcrystalline cellulose) degradation zone of clearance on agar platefrom rice field soil resulted approximately at 25 mm, 24 mm and 22 mm respectively. As for cow farm soil, CMC, xylan and Avicel degradation clearancezone on agar plate resulted around at 24mm, 23mm and 21 mm respectively. Rotten rice straw from cow farm also resulted for CMC, xylan and Avicel degradation zone almost at 24 mm, 23 mm and 22 mm respectively. The objective of this study is to isolatebiomass degrading microbial strains having good efficiency in cellulose hydrolysis and observed the effects of different substrates (CMC, xylan and Avicel) on the production of cellulase enzymes (endo-glucanase, exo-glucanase, cellobiase, xylanase and avicelase) for producing low cost biofuel from cellulosic materials.

• 신재생에너지
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• 제6권4호
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• pp.6-14
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• 2010

Pretreatment of cellulosic biomass is necessary before enzymatic saccharification and fermentation. Extrusion is a well established process in food industries and it can be used as a physicochemical treatment method for cellulosic biomass. Aqueous ammonia soaking treatment at mild temperatures ranging from 60 to $80^{\circ}C$ for longer reaction times has been used to preserve most of the cellulose and hemicellulose in the biomass. The objective of this study was to evaluate the effect of extrusion treatment on aqueous ammonia soaking method. Extrusion was performed with miscanthus sample conditioned to 2mm of particle size and 20% of moisture content at $200^{\circ}C$ of barrel temperature and 175rpm of screw speed. And then aqueous ammonia soaking was performed with 15%(w/w) ammonia solution at $60^{\circ}C$ for 1, 2, 4, 8, 12 hours on the extruded and raw miscanthus samples respectively. In the combined extrusion-soaking treatment, most compositions removal occurred within 1~2 hours and on a basis of 1 hour soaking treatment values, cellulose was recovered about 85% and other compositions, including hemicellulose, are removed about 50% from extruded miscanthus sample. The combined extrusion-soaking treated and soaking only treated samples were subjected to enzymatic hydrolysis using cellulase and ${\beta}$-glucosidase. The enzymatic digestibility value of combined extrusion-2 hours soaking treated sample was comparable to 12 hours soaking only treated sample. It means that extrusion treatment can shorten the conventional long reaction time of aqueous ammonia soaking. The findings suggest that the combination of extrusion and soaking is a promising pretreatment method to solve both problems for no lignin removal of extrusion and long reaction time of aqueous ammonia soaking.

• 한국응용과학기술학회지
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• 제33권4호
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• pp.627-633
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• 2016

단수수[Sorghum bicolor (L)]는 당류가 풍부한 사탕수수, 사탕무와 같은 주요 바이오연료 작물 중의 하나이다. 단수수 착즙액은 단수수 줄기를 압착하여 추출하며 주요 성분는 glucose와 fructose 그리고 sucrose로 구성되어 있다. 에탄올은 효모발효공정을 통하여 단수수 착즙액으로부터 쉽게 생산할 수 있다. 단수수 착즙액은 당류 뿐만 아니라 질소나 인산과 같은 다양한 무기영양원도 함유하고 있어 종균 배지로 활용성이 높다. 상업적인 에탄올 생산 공정에서 종균배양은 중요한 발효공정 중의 하나이며 공정비용 절감을 위해 최적화된 배지가 필수적이다. 본 연구에서는 섬유질계 바이오에탄올 생산을 위한 종균의 배지로서 단수수 착즙액의 특성을 평가하였다. 단수수착즙액의 발효기질 적합성을 평가하기 위해 YPD 및 억새 당화액을 비교하여 실험하였으며, YPD배지 중 yeast extract 와 peptone은 각각 5 g/L의 농도로 사용하였다. 각각의 기질들은 당 농도가 2%, 5%, 10%가 함유되도록 제조하여 발효를 통한 균체농도를 측정하였다. 그 결과 YPD와 단수수착즙액을 배지로 사용하였을 때 발효 24시간 후에 최대 $2.5{\times}10^8CFU/mL$ 이상의 균체농도를 나타내었다. 결과적으로 단수수착즙액은 12시간 발효 후에 $1.0{\times}10^8CFU/mL$ 균체를 생산하여 섬유질계 바이오에탄올 생산을 위한 종균 배지로서 YPD를 대체하여 사용할 수 있음을 확인하였다.