지질추출 미세조류 폐기물로부터 바이오 수소 생산 향상을 위한 전처리의 적용

김태훈,임병서,박혜숙,윤여명 대한환경공학회 2019 대한환경공학회지 Vol.41 No.9

Objectives : This study was performed to investigate optimal conditions for fermentative hydrogen production of lipid-extracted microalgae waste (LMW) by single and combined pretreatments. Methods : To produce LMW as a feedstock, the lipids were extracted from Chlorella vulgaris by conventional method and the LMW concentration was controlled at 75 g dry cell weight (dcw)/L. LMW pretreatment was performed by single (alkali, acid, and ultrasonic (U/S)) and combined (alkali+ultrasonic, acid+ultrasonic) pretreatment. For performing dark fermentative hydrogen production, LMW was added on the basis of a solid/liquid ratio (S/L ratio) of 1 : 10 and the heat-treated sludge at 90℃ for 20 min was inoculated in batch reactors. After the batch experiment, microbial community analysis was performed by Next Generation Sequencing (NGS). Results and Discussion : The acid pretreatment showed the greatest influence on the increase of the solubilization rate among three single pretreatment methods. On the other hand, the ultrasonication pretreatment did not lead to increasing the solubilization but showed increased hydrogen production (197 mL H2/g (dcw)) as much as the single acid pretreated methods. The combined pretreatment resulted in the highest 6,880 mg COD/L in the sample pretreated by the acid (1.5% HCl) combined with the single ultrasonic method, but the highest hydrogen production of 237 mL H2/g (dcw) was obtained in the sample pretreated by the acid (1.0% HCl) combined with ultrasonic. However, the alkali combined with ultrasonic combined pretreatment method showed a slight increase in hydrogen production compared to control one. Microbial community analysis revealed that the relative abundance of genera Clostridium was 97.1% in the sample pretreated by combined pretreatment (1.5% HCl+ultrasonic). Conclusions : The improvement of hydrogen production was closely related to the increase of SCOD in both samples employed by single and combined pretreatment. Especially, the application of acid pretreatment method was found to be more effective than alkali pretreatment. Ultrasonic pretreatment, on the other hand, did not result in increased SCOD, but improved hydrogen production. This might be due to that physical structure of LMW was disrupted and became easier biodegradable, even if the solubilization of the substrate did not proceed through the pretreatment of the ultrasonic method. According to the result of NGS analysis, high abundance of Clostridium spp. played the main role in hydrogen production. 목적 : 본 연구는 지질추출 미세조류 폐기물(Lipid-extracted microalgae waste, LMW)을 기질로 이용하여 혐기성 수소 암 발효 생산에서 산, 알칼리, 초음파 단독 전처리 및 병합 전처리를 통해 최적의 조건을 연구했다. 방법 : 기질로 선택한 미세조류는 표준방법을 통해 지질추출을 하여 최종 LMW 농도는 75 g dry cell weight (dcw)/L로고정하였다. LMW 전처리는 알칼리, 산, 초음파(Ultrasonication, U/S), 알칼리+초음파, 산+초음파 병합 방법을 진행하였다. 수소 생산 회분식 반응조 세팅을 위해 LMW는 고상 : 액상 혼합비율(Solid/liquid ratio, S/L ratio)을 1 : 10을기준으로 하였고 열처리된 슬러지(90℃, 20분)를 식종했다. 회분식 실험 후, 유기산 분석과 Next generation sequencing (NGS) 방법을 적용한 미생물 군집 분석을 했다. 결과 및 토의 : 단독 전처리 과정에서 산 전처리가 가용화율 증가에 가장 큰 영향을 미치는 것으로 나타났다. 반면, 초음파 단독 전처리는 가용화율 증가에 큰 영향을 주지 않았지만 산(1.5% HCl) 전처리와 같이 가장 높은 수소 전환율(197 mL H2/g (dcw))을 나타냈다. 병합 전처리의 경우, 산(1.5% HCl)+초음파 전처리 조건에서 가장 높은 6,880 mg COD/L을 보였으나 산(1.0% HCl)+초음파 병합 전처리에서 237 mL H2/g (dcw)의 가장 높은 수소 생산의 결과를보였다. 반면, 알칼리+초음파 병합 전처리 방법은 수소 생산 증가율은 아주 미미했다. 미생물 군집 분석의 결과, 수소 생산 대표 미생물인 Clostridium 속의 상대적 우점도는 대조군에서 91.8%로 가장 낮았던 반면에 산(1.5% HCl)+초음파 병합 전처리가 가장 높은 97.1% 우점도의 결과를 보였다. 결론 : 수소 전환율의 향상은 대부분 단독・병합 전처리 모두 SCOD 증가와 밀접한 관계가 있었으며, 특히 산 전처리 방법의 적용이 알칼리 전처리 적용과 비교하여 효과적임을 확인했다. 반면, 초음파 전처리의 경우 낮은 SCOD 증가에 기인하지 않았지만, 높은 수소 전환율의 결과를 보여주었다. 이는 초음파 전처리를 통해 기질의 완전한 가용화까지 진행되지 않았지만 미생물의 생분해가 쉬운 형태로 전처리가 되어 수소 생산율의 증가에 기인했을 것으로 판단된다. NGS 분석 결과에 따라 Clostridium 속 미생물에 의한 수소 생산이 주가 되었던 것으로 나타났고 이들의 우점도는 수소 생산량과 비례함의 결과를 보였다.

Effect of Two-Stage Pretreatment of Reed (Phragmites Australis) on Glucose Conversion and Ethanol Production Enhancement

Si Young Ha,Ji-Su Kim,Ji Young Jung,Jae-Kyung Yang 한국산림바이오에너지학회 2019 산림바이오에너지 Vol.29 No.2

Chemical treat after steam explosion has been used extensively to efficiently recover hemicellulose-derived sugars in their monomeric form and to improve enzymatic hydrolysis of the cellulosic residues. It has also been shown that, under severe pretreatment conditions, complete enzymatic hydrolysis of the cellulose-rich residue can be achieved. In this paper, two-stage pretreatment (steam explosion pretreatment followed by chemical pretreatment) was performed to improve glucose conversion in reed (Phragmites australis). Steam explosion and chemical pretreatment were studied using the R0 4.03 and multiple solvents (1% NaOH, 1% H₂O₂ and methanol), respectively, to optimize glucose conversion. The optimum pretreatment conditions were investigated, and the maximum glucose conversion was compared. The maximum glucose conversion improvement due to steam explosion pretreatment of reed was 70.0% based on cellulose content using R0 4.03. Furthermore, the maximum glucose conversion improvement due to chemical pretreatment of steam exploded reed was 98.5% based on cellulose content using alkaline peroxide (1% H₂O₂). In conclusion, enzymatic hydrolysis and ethanol production resulted in 98.5% of glucose conversion based cellulose content of insoluble fraction after alkaline peroxide (1% H₂O₂) pretreatment and 8.0 g/raw material 100g of bioethanol, respectively, with the two-stage pretreatment conditions of R0 4.03 steam explosion pretreatment and 1% H₂O₂ chemical pretreatment. The two-stage pretreatment of reed followed by coupled enzymatic hydrolysis and fermentation can be considered a promising method for second generation bioethanol production.

돌산갓 전처리 중의 산도, 항균선 및 색도 변화

박석규,서권일,이상원,조영수,손미혜 동아시아식생활학회 1997 동아시아식생활학회지 Vol.7 No.1

In order to use leaf mustard Dolsan food preservative ingradient, acidity, antimicrobial activity and colors were investigated during pretreatment of leaf mustard Dolsan. pH was remarkably decreased after 8 hours to pretreatment(extracted on shaking) of leaf mustard Dolsan, and no changes were observed after that time. pH of leaf part was higher than stalk after 8 hours storage. Titratable acidity was opposite tendency to the pH, pH was gradually decreased than initial stage during pretreatment: of leaf mustard Dolsan at 30, 40 and 50℃. After 16 hours pretreatment, the higher pretreatment temperature was, the higher pH was, but after pretreatment for 48 hours, pH of sample pretreated at 50℃ was lower than that of sample pretreated at 40℃. Antimicrobial activity of leaf mustard Dolsan extract pretreated at 30℃ was the strongest of the samples pretreated at 30, 40 and 50℃, and that of stalk part was stronger than that of leaf part. L and b value in colors was gradually decreased, and a value was increased with the passage of pretreatment time. L and b value was higher in the order of samples pretreated at 40, 50 and 30℃, and the lower pretreatment temperature was, the higher a value was. L value of stalk part was higher than that of leaf part, but a and b value of of leaf part was higher than that of stalk part.

고추의 약배양 시 온도 전처리에 따른 소포자의 세포학적 변화 분석

김문자,장인창 한국식물생명공학회 2001 식물생명공학회지 Vol.28 No.5

고추의 약을 배지에 치상한 후 4$^{\circ}C$와 32$^{\circ}C$의 온도 전처리가 소포자의 활력, 초기분열 및 소포자 배 발생에 미치는 영향을 조사하였다. 활력 있는 소포자의 비율은 모 식물에서 채취하여 치상할 당시에는 62~64%정도였으나 치상 후 온도처리 기간 중에는 매우 급속하게 저하되었다. 소포자의 활력은 4$^{\circ}C$ 처리에 비해 32$^{\circ}C$ 처리 시에 더욱 심하게 감소하였으며 배양 9일이 되면 온도처리와 관계없이 활력 있는 소포자가 거의 없었다. 치상 당시의 소포자는 대부분이 후기 1핵성 소포자기였으며 배양 2일 후부터 핵이 소실된 무핵 소포자들과 함께 다양한 유형의 다핵 소포자들이 나타났다. 배 발생적 소포자의 비율은 고온처리에서 높았으나 균등분열에 의한 동형2핵 소포자의 출현에는 온도처리에 따른 차이가 크지 않았으며 다핵 소포자들은 균등 또는 불균등 분열에 의해 생겨났다. $25^{\circ}C$와 32$^{\circ}C$ 처리에서는 배양 2일 후에 이미 퇴화 소포자들이 50% 이상이 되었는데 4$^{\circ}C$ 처리에서는 14일 동안 대부분의 소포자들에서 핵이 완전하였다. 소포자 배의 발생은 4$^{\circ}C$ 처리에 비해 32$^{\circ}C$ 처리에서 높았으며 가장 효과적인 고온처리 기간은 4일이었다. 이에 비해 4$^{\circ}C$ 처리에서는 2일 처리가 가장 효과적이었으며 처리기간이 길어질수록 소포자 배의 발생이 감소되었다. Inoculated anthers of Capsicum annuum L. were subjected to 4 and 32$^{\circ}C$ pretreatment and their influence on the microspore viability, early cytological changes and the induction frequency of microspore embryo was investigated. Viability of freshly isolated microspores was between 62 and 64%. During temperature pretreatment, microspore viability showed a rapid decrease and this tendency enhanced with the 32$^{\circ}C$ pretreatment. Irrespective of temperature pretreatment, microspore viability declined to nearly zero after nine days. Before temperature pretreatment, most of the microspores in anthers were at late uninucleate stage. Several types of multinuclear microspores appeared from the 2 day after culture onwards, together with many degenerated and non-induced microspores. The 32$^{\circ}C$ pretreatment gave higher proportions of embryogenic microspore than other treatment. However, the temperature pretreatment had no clear effect on the frequencies of symmetrical binucleate rnicrospore. The multinucleate grains might originate either by symmetrical or asymmetrical division. After 2 days of pretreatment at 25 and 32$^{\circ}C$ , degenerated microspore increased above 50%. In contrast, during 4$^{\circ}C$ treatment, nucleus of most microspores remained intact for 14 days. The 32$^{\circ}C$ pretreatment produced more embryos than 4$^{\circ}C$ treatment. The most effective period of 32$^{\circ}C$ pretreatment was 4 days. In contrast, effective period of 4$^{\circ}C$ pretreatment was 2 days and longer time had deleterious effect on induction of microspore embryo.

Volatile fatty acid recovery by anaerobic fermentation from blue-green algae: Effect of pretreatment

Cho, Hyun Uk,Kim, Hye Gyeong,Kim, Young Mo,Park, Jong Moon Elsevier 2017 Bioresource technology Vol.244 No.2

<P><B>Abstract</B></P> <P>The aims of this study were to quantify how pretreatment affects production of volatile fatty acids (VFAs) from cyanobacterial biomass and production of subsequent microbial lipid by an oleaginous microorganism that uses the VFAs as carbon sources. The highest biomass solubilization was obtained using thermal-alkaline (th-alkaline) pretreatment (33.1%), followed by alkaline pretreatment (29.1%), and thermal pretreatment (7.2%), but the highest VFA yield was obtained using alkaline pretreatment (0.54±0.02g/gVS), followed by the untreated condition (0.47±0.03g/gVS), and th-alkaline pretreatment (0.44±0.02g/gVS). Although VFA yield was higher using alkaline pretreatment condition than in the untreated condition, the difference was not great. However, lipid productivity by <I>Cryptococcus curvatus</I> after the alkaline pretreatment condition was 2.0-fold higher than that under the untreated condition. This study confirmed the feasibility of using biologically produced VFAs from cyanobacterial biomass for microbial lipid production by the oleaginous microorganism.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cyanobacterial biomass solubilization was augmented by all pretreatments. </LI> <LI> The highest biomass solubilization did not result in the highest VFA production. </LI> <LI> The highest VFA yield was obtained using alkaline pretreatment. </LI> <LI> VFAs derived from cyanobacterial biomass were converted into lipids by <I>C. curvatus</I>. </LI> <LI> The combination of alkaline pretreatment and <I>C. curvatus</I> cultivation is efficient. </LI> </UL> </P>

Influence of pretreatment condition on the fermentable sugar production and enzymatic hydrolysis of dilute acid-pretreated mixed softwood

Lim, W.S.,Lee, J.W. Elsevier Applied Science 2013 Bioresource technology Vol.140 No.-

In this study, the effects of different acid catalysts and pretreatment factors on the hydrolysis of mixed softwood were investigated over a range of thermochemical pretreatments. Maleic, oxalic, and sulfuric acids were each used, under different pretreatment conditions. The most influential factor for fermentable sugar production in the dicarboxylic acid pretreatment of softwood was the pH. Reaction temperature was the next significant factor. However, during sulfuric acid pretreatment, fermentable sugar production was more dependent on reaction temperature, than time or pH. Enzymatic hydrolysis yields differed, depending on acid catalyst and pretreatment factor, regardless of lignin content in pretreated biomass. The highest enzymatic hydrolysis yield was found following maleic acid pretreatment, which reached 61.23%. The trend in enzymatic hydrolysis yields that were detected concomitantly with pretreatment condition or type of acid catalyst was closely related to the fermentable sugar production in the hydrolysate.

Pretreatment of agricultural biomass for anaerobic digestion: Current state and challenges

Paudel, Shukra Raj,Banjara, Sushant Prasad,Choi, Oh Kyung,Park, Ki Young,Kim, Young Mo,Lee, Jae Woo Elsevier Applied Science 2017 Bioresource technology Vol.245 No.1

<P><B>Abstract</B></P> <P>The anaerobic digestion (AD) of agricultural biomass is an attractive second generation biofuel with potential environmental and economic benefits. Most agricultural biomass contains lignocellulose which requires pretreatment prior to AD. For optimization, the pretreatment methods need to be specific to the characteristics of the biomass feedstock. In this review, cereal residue, fruit and vegetable wastes, grasses and animal manure were selected as the agricultural biomass candidates, and the fundamentals and current state of various pretreatment methods used for AD of these feedstocks were investigated. Several nonconventional methods (electrical, ionic liquid-based chemicals, ruminant biological pretreatment) offer potential as targeted pretreatments of lignocellulosic biomass, but each comes with its own challenges. Pursuing an energy-intensive route, a combined bioethanol-biogas production could be a promising a second biofuel refinery option, further emphasizing the importance of pretreatment when lignocellulosic feedstock is used.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pretreatment is guided for anaerobic digestion of agricultural biomass. </LI> <LI> Characteristics of feedstock must be considered for optimizing pretreatment. </LI> <LI> Alkali and steam explosion leads to an enhanced anaerobic digestion performance. </LI> <LI> PEF, ionic liquids and rumen system can be future challenges for pretreatment. </LI> <LI> Pretreatment is significant in a combined biorefinery with agricultural residue. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

에탄올 유기용매 전처리를 이용한 옥수수대의 효소당화

박장한 ( Jang Han Park ),김태현 ( Tae Huyn Kim ),김준석 ( Jun Seok Kim ) 한국화학공학회 2016 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.54 No.4

This study is for the effective pretreatment and saccharification of lignocellulosic biomass for a transport fuel receiving attention. The waste water during the pretreatment of biomass is major factor for determining the price of biofuel. Therefore, we conducted high concentration of organosolv pretreatment for decline waste water and reusing the solvent. We confirmed effect of organosolv pretreatment by components analysis and enzymatic hydrolysis of pretreated biomass. The corn stover was used for and 99.5 wt% of ethanol as a organosolv pretreatment. The pretreatment condition was varied 130 to 190℃ during the designated reaction times and the effect of pretreatment was investigated by enzymatic hydrolysis. The highest glucose conversion was more than 68% the pretreatment condition of 190℃ for 70 min or more. The solid remaining was more than 70% and almost of cellulose and hemicellulose were survived.

Effect of Organosolv Pretreatment on Mechanically Pretreated Biomass by Use of Concentrated Ethanol as the Solvent

박용철,김태현,김준석 한국생물공학회 2017 Biotechnology and Bioprocess Engineering Vol.22 No.4

In this study, we determined the effect of organosolv pretreatment on herbaceous biomasses corn stover and wheat straw, by using high-concentration ethanol as the solvent. A high-concentration of ethanol allows for the easy reuse and recycling of the solvent. First, we tested the effects of ethanol pretreatments at 60 and 99.5% (w/w) and found that highest solvent concentration resulted in low glucose digestibility. The maximum enzymatic glucose digestibility with 60% ethanol was 92.6% at 190oC for 120 min (using corn stover) and 86.9% at 190oC for 120 min (using wheat straw). In contrast, the digestion rates with 99.5% ethanol were 68.8 and 77.4% under the same conditions, respectively, indicating that there is a limit to the use of high-concentration ethanol as the solvent. To overcome this limitation, we applied a mechanical pretreatment step before the chemical pretreatment. Subsequently, glucose digestibility increased significantly to 93.1% with 99.5% ethanol as the solvent. Additionally the enzymatic digestibility of mechanically pretreated corn stover was higher than that of non-pretreated corn stover by about 40%. Taken together, these results confirm the efficacy of using high-concentration ethanol as a solvent for organosolv pretreatment when done in conjunction with mechanical pretreatment.

Improved pretreatment of yellow poplar biomass using hot compressed water and enzymatically-generated peracetic acid

Lee, Hyeong Rae,Lee, Hun Wook,Lee, Youn-Woo,Kazlauskas, Romas J.,Park, Tai Hyun Elsevier 2017 Biomass & bioenergy Vol.105 No.-

<P><B>Abstract</B></P> <P>Biomass forms a complex interwoven structure containing cellulose, hemicellulose and lignin that hinders enzymatic hydrolysis of cellulose. Enzymatic hydrolysis of the cellulose within yellow poplar (tulip tree) particles released only 9% of the total glucose in this study. To increase the accessibility of the cellulose component, wood particles were pretreated using hot compressed water and enzymatically-generated peracetic acid. The combined pretreatment started with hot compressed water (200 °C, 15 min), which selectively solubilized up to 90% of the xylan. The remaining solid was treated with peracetic acid (90 mM, 60 °C, 6 h), which solubilized up to 70% of the lignin. The remaining solid consisted of mainly glucan (∼75%) and corresponds to 87% of the glucan initially present in the yellow poplar particles. Hydrolysis of the remaining solid using a low loading of cellulase/β-glucosidase for 72 h released 90% of the glucose. The removal of the xylan and lignin structural barriers dramatically increased the cellulase accessibility to cellulose. The structural characteristics (crystallinity, functional group changes, morphology) of combined pretreated solid residue changed in a manner consistent with increased enzymatic digestibility. The combined pretreatment with hot compressed water and peracetic acid was more effective than either single pretreatment and more effective than the sum of the single pretreatments to remove xylan and lignin, thus demonstrating a cooperative effect of the two pretreatments. In addition, the combined pretreatment enhanced the accessibility of cellulases to the cellulose resulting in more efficient cellulose hydrolysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hot compressed water pretreatment of yellow poplar hydrolyzed xylan to xylose. </LI> <LI> Subsequent peracetic acid treatment solubilized lignin leaving a glucan-rich solid. </LI> <LI> Combined pretreatment removes more lignin than the sum of individual pretreatments. </LI> <LI> Combined pretreatment could enhance enzymatic digestibility and reduce the amount of cellulase needed. </LI> <LI> This fractionation of the major components of biomass allows separate uses for each component. </LI> </UL> </P>