利用树干毕赤酵母发酵玉米秸秆制备燃料酒精

采用湿热预处理(195℃,15min)与同步糖化发酵对玉米秸秆制备酒精进行了研究。结果表明:玉米秸秆经过湿热预处理后,86.5%纤维素保留在滤饼中,而大部分半纤维素被溶解。在底物质量体积含量50g/L,温度30℃,pH值5.5,摇床转速130r/min条件下,树干毕赤酵母(Pichia stipitis)利用预处理后的玉米秸秆经过192h同步糖化发酵,酒精浓度达到了12.12g/L,对应的酒精产量和生产效率分别为0.34g/g(葡萄糖+木糖)和0.065g/(L·h)。该项研究为工业化生产打下了基础。     

预处理方法对玉米秸秆发酵产氢的影响及其机理分析

研究了不同预处理方法对玉米秸秆发酵产氢气的影响和秸秆降解产氢的机理。实验分别采用酸解(AP)、酸解耦合固态酶解(AEP)、高温蒸煮(HP)和高温蒸煮耦合固态酶解(HEP)的玉米秸秆进行发酵产氢,分析预处理后秸秆累积产氢量与可溶性糖含量的关系。在此基础上,通过秸秆化学组成成分分析、傅里叶变换红外光谱(FT-IR)和X-射线衍射分析,探讨了秸秆降解的机理。结果表明,秸秆的累积产氢量与可溶性糖含量基本正相关,秸秆糖化效率是影响秸秆累积产氢量的主要因素。四种预处理方法主要作用于秸秆半纤维素和纤维素的无定型区,预处理过程皆在不同程度上提高了秸秆的结晶度,并在极大程度上提高了玉米秸秆的累积产氢量。其中AEP方法预处理秸秆效果最好,累积产氢量达到了226.1 m L·(g·TS)-1。     

预处理方法对玉米秸秆利用的影响

分别用化学方法(稀硫酸、氢氧化钠、聚乙二醇-4000、曲拉通X-100)和物理方法(液氮超低温处理)对玉米秸秆进行预处理,比较了预处理后木质纤维素酶降解的效果。结果表明:氢氧化钠和液氮超低温处理的降解效率比较好,生成的糖最多。扫描电镜检测证明预处理后的秸秆物理结构发生了较大改变。对预处理后的秸秆进行发酵产沼气能力比较的结果表明,液氮处理后的秸秆产沼气的量最多。     

玉米秸秆发酵生产乙醇的研究

以1.5%硫酸120℃处理60min、又被1%氢氧化钠80℃处理60min的玉米秸秆为底物。正交优化了利用其糖化液发酵产乙醇的条件,在温度34℃、酵母接种量4%(体积分数)、玉米浆加量0.4%(体积分数)的发酵条件下反应48h产生乙醇40.2g/L,纤维素乙醇转化率为86%。     

不同脱毒方法对玉米秸秆水解液酒精发酵的影响

利用湿热预处理(195℃,15 min)后的玉米秸秆水解液,考察了3种不同脱毒方法(中和法、饱和生石灰法和Na2SO3法)对水解液中的抑制剂的去除效果,研究了树干毕赤酵母(Pichia stipitis 58376)对脱毒后的水解液酒精发酵情况.结果表明:玉米秸秆水解液经过3种方法脱毒处理后,醛类抑制荆(糠醛和5-羟甲...     

木薯酒精渣的预处理及补料同步糖化发酵制取乙醇

木薯酒精渣的处置是制约木薯燃料乙醇大规模产业化的问题之一。本文立足于探索木薯酒精渣利用途径,分析了木薯酒精渣的主要成分,对比了氨水、氢氧化钠、氨水组合稀硫酸3种预处理方式对于木薯酒精渣纤维素和木素含量及纤维素酶水解效率的影响,分析了处理前后木薯酒精渣的表面结构及纤维素结晶度,并以氨水处理后的木薯酒精渣为底物,进行了同步糖化发酵。结果表明,3种预处理方法中组合预处理能更好地增加纤维素含量和提高纤维素酶水解效率,与未处理原料相比,组合预处理后纤维素含量增加了111.26%,木素下降了35.05%,酶水解72h纤维素转化率从42.10%增加到61.71%。氨水预处理后,原料的木素含量降低,处理后木薯酒精渣的表面变得更加粗糙,纤维素结晶度有所增加,以氨水处理后的木薯酒精渣为底物进行分批补料同步糖化发酵,当初始底物浓度为100.0g/L,分别在20h、40h、60h进行补料至最终底物浓度为400.0g/L时,发酵120h乙醇浓度达到51.0g/L。     

吉林用玉米秸秆生产酒精项目获阶段性成果

日前，吉林省轻工业设计研究院和吉林沱牌农产品开发有限公司共同承担的“玉米秸秆湿氧化预处理生产酒精的研究”项目，通过了阶段性成果鉴定。在项目的实验室条件下，玉米秸秆经湿氧化预处理后在10L全自动发酵罐试验中，发酵62h，酒精度达到6．2％（体积分数），且工艺路线可行，为示范生产线提供了技术参数。同时课题组与丹麦瑞速国家实验室合作，采用的玉米秸秆湿氧化预处理技术使按实验室指标测算的玉米秸秆酒精与玉米酒精成本相当。该成果对缓解我国能源紧缺、深入开发利用秸秆资源、减少污染具，有重要意义。     

有机溶剂预处理对玉米秸秆结构影响的初探

本文旨在初步探索有机溶剂预处理对农林废弃物结构的影响.以玉米秸秆为样品,用水(对比参照)和有机溶剂(丙酮、乙酸、乙醇)分别对玉米秸秆进行萃取预处理,将滤液、滤渣称重,并进行红外分析.结果表明,有机溶剂的预处理效果较好,萃取率由高到低的顺序为乙酸、丙酮、乙醇,有机溶剂的极性和溶解性共同决定了预处理效果.残渣和萃取液的结构...     

秸秆酒精发酵废液对番茄生长与产量的影响

秸秆酒精发酵废液中含有大量的生化黄腐酸。采用盆栽试验研究了秸秆酒精发酵废液对于番茄生长发育的影响。结果表明,与CK相比,施用秸秆酒精发酵废液干粉可促进番茄生长,株高、茎粗显著增加;番茄初果期超氧化物歧化酶活性、总叶绿素含量显著增加,丙二醛含量降低;番茄单株产量明显增加,增产率达12.19%。这说明秸秆酒精发酵废液可作为新型肥料的原料使用,对其进行综合利用,具有重要的经济效益和生态效益。     

木薯酒精渣同步糖化发酵制乙醇的工艺研究

研究了利用木薯酒精厂废渣为原料发酵生产乙醇的方法,结果表明:经过简单的机械粉碎后,通过同步糖化发酵生产乙醇是可行的。发酵条件为:木薯酒精渣经粉碎后取粒径小于0.85mm的部分,初始料水比1∶8,纤维素酶添加量为每克木薯渣(干重)30FPU,发酵过程中在24h内分批将剩余木薯渣加入至总料水比达到1∶2.5,利用5L发酵罐进行同步糖化发酵,发酵液中乙醇质量浓度达到52g/L,木薯酒精渣到乙醇的收率达到13%。纤维素酶的添加量对发酵效果影响显著,当达到每克木薯渣(干重)50FPU时,发酵液中乙醇质量浓度可达65g/L,乙醇收率达到16%。     

Simultaneous saccharification and fermentation of pretreated Antigonum leptopus (Linn) leaves to ethanol

Simultaneous saccharification and fermentation (SSF) of alkaline hydrogen peroxide pretreated Antigonum leptopus (Linn) leaves to ethanol was optimized using cellulase from Trichoderma reesei QM‐9414 (Celluclast® from Novo) and Saccharomyces cerevisiae NRRL‐Y‐132 cells. Contrary to the saccharification optima (2.5% w/v substrate concentration, 50 °C, 4.5 pH, 40 FPU cellulase g⁻¹ substrate and 24 h reaction time), the SSF optima was found to be somewhat different (10% w/v substrate, 40 °C, 100 FPU cellulase g⁻¹ substrate and 72 h). Better ethanol yields were obtained with SSF compared with the traditional saccharification and subsequent fermentation (S&F) and when the cellulase was supplemented with β‐glucosidase. © 1999 Society of Chemical Industry     

Comparisons of existing pretreatment,saccharification, and fermentation processes for butanol production from agricultural residues

Some of the most recent, relevant, industrial and academic contributions made in the field of butanol production are reviewed here. The focus on butanol is due to the growing demand for non‐fossil biofuels. In addition, butanol can be mixed with fossil fuels or can be used alone, allowing an alternative to gasoline. Butanol can be synthesised biologically using sugars extracted from biomass such as agricultural waste. This agricultural waste must be pretreated before it is suitable for sugar extraction. Following this stage, enzymatic hydrolysis is employed, before performing fermentation using microorganisms. This article summarises some of the economical methods such as simultaneous saccharification and fermentation (SSF). Different pretreatment and saccharification processes were compared. Acid pretreatment and saccharification achieved the highest sugar concentrations from wheat straw. Monoethanolamine pretreatment achieved highest sugars from hardwood. Comparisons and analysis of different types of fermentation processes illustrated that immobilised reactor provided the best butanol rate of production. Integration of fermentation with product removal process improved butanol production in immobilised reactor. Gas stripping method was illustrated to be the product removal process. © 2011 Canadian Society for Chemical Engineering     

Detoxification and concentration of corn stover hydrolysate and its fermentation for ethanol production

Environmental and energy concerns have increased interest in renewable energy sources, particularly biofuels. Thus the fermentation of glucose from sulfuric acid-hydrolyzed corn stover for the production of bioethanol has been explored using a combined acid retardation and continuous-effect membrane distillation treatment process. This process resulted in the separation of the sugars and acids from the acid-catalyzed hydrolysate, the removal of most of the fermentation inhibitors from the hydrolysate and the concentration of the detoxified hydrolysate. The recovery rate of glucose from the sugar-acid mixture using acid retardation was greater than 99.12% and the sulfuric acid was completely recovered from the hydrolysate. When the treated com stover hydrolysate, containing 100 g/L glucose, was used as a carbon source, 43.06 g/L of ethanol was produced with a productivity of 1.79 g/(L· h) and a yield of 86.31 %, In the control experiment, where glucose was used as the carbon source these values were 1.97 g/(L·h) and 93.10% respectively. Thus the integration of acid retardation and a continuous-effect membrane distillation process are effective for the production of fuel ethanol from com stover.     

Simultaneous saccharification and fermentation of alkaline-pretreated corn stover to ethanol using a recombinant yeast strain

Bio-ethanol converted from cheap and abundant lignocellulosic materials is a potential renewable resource to replace depleting fossil fuels. Simultaneous saccharification and fermentation (SSF) of alkaline-pretreated corn stover for the production of ethanol was investigated using a recombinant yeast strain Saccharomyces cerevisiae ZU-10. Low cellobiase activity in Trichoderma reesei cellulase resulted in cellobiose accumulation. Supplementing the simultaneous saccharification and fermentation system with cellobiase greatly reduced feedback inhibition caused by cellobiose to the cellulase reaction, thereby increased the ethanol yield. 12 h of enzymatic prehydrolysis at 50 °C prior to simultaneous saccharification and fermentation was found to have a negative effect on the overall ethanol yield. Glucose and xylose produced from alkaline-pretreated corn stover could be co-fermented to ethanol effectively by S. cerevisiae ZU-10. An ethanol concentration of 27.8 g/L and the corresponding ethanol yield on carbohydrate in substrate of 0.350 g/g were achieved within 72 h at 33 °C with 80 g/L of substrate and enzyme loadings of 20 filter paper activity units (FPU)/g substrate and 10 cellobiase units (CBU)/g substrate. The results are meaningful in co-conversion of cellulose and hemicellulose fraction of lignocellulosic materials to fuel ethanol.     

Enzymatic hydrolysis and fermentation of lime pretreated wheat straw to ethanol

BACKGROUND: The objective of this work is to develop an efficient pretreatment method that can help enzymes break down the complex carbohydrates present in wheat straw to sugars, and to then ferment of all these sugars to ethanol. RESULTS: The yield of sugars from wheat straw (8.6%, w/v) by lime pretreatment (100 mg g^?1 straw, 121 °C, 1 h) and enzymatic hydrolysis (45 °C, pH 5.0, 120 h) using a cocktail of three commercial enzyme preparations (cellulase, β‐glucosidase, and xylanase) at the dose level of 0.15 mL of each enzyme preparation g^?1 straw was 568 ± 13 mg g^?1 (82% yield). The concentration of ethanol from lime pretreated enzyme saccharified wheat straw (78 g) hydrolyzate by recombinant Escherichia coli strain FBR5 at pH 6.5 and 35 °C in 24 h was 22.5 ± 0.6 g L^?1 with a yield of 0.50 g g^?1 available sugars (0.29 g g^?1 straw). The ethanol concentration was 20.6 ± 0.4 g L^?1 with a yield of 0.26 g g^?1 straw in the case of simultaneous saccharification and fermentation by the E. coli strain at pH 6.0 and 35 °C in 72 h. CONCLUSION: The results are important in choosing a suitable pretreatment option for developing bioprocess technologies for conversion of wheat straw to fuel ethanol. Copyright © 2007 Society of Chemical Industry     

高底物浓度纤维乙醇同步糖化发酵工艺的比较

引言日益加剧的能源危机和环境污染,正迫使人们寻求新的可再生替代能源。纤维乙醇作为一种重要的生物质替代能源,经过近40多年的发展,已经具备了实现工业化生产的潜力。为了进一步降低纤     

Production of fuel ethanol from softwood by simultaneous saccharification and fermentation at high dry matter content

BACKGROUND: The production of bio‐ethanol from softwood is considered a promising alternative to fossil fuels in Sweden. In order to make fuel ethanol economically competitive with fossil fuels, it is important to reduce the production cost, which can be done by increasing the dry matter content of the fermentation medium, thus reducing the energy demand in the final distillation of the fermentation broth. Running simultaneous saccharification and fermentation (SSF) at higher dry matter content has, however, been found to decrease the ethanol yield. RESULTS: The use of different stirrer types and stirring speeds in the present study has shown to have an influence on the final ethanol yield in SSF with 10% water‐insoluble solids (WIS). Also, higher concentration of pretreatment hydrolysate, i.e., with increased inhibitor concentration, at the same WIS resulted in a decreased ethanol yield. However, despite stirring problems and high inhibitor concentration, ethanol was produced at 12% WIS with an ethanol yield in the SSF step of 81% of the theoretical based on the content of fermentable sugars in the fermentor. CONCLUSION: The decrease in ethanol yield in SSF at high dry matter content has been shown to be a combined effect of increased mass transfer resistance and increased inhibitor concentration in the fermentation broth. Copyright © 2008 Society of Chemical Industry     

蒸汽爆破麦草同步糖化发酵转化乙醇的研究

近年来对木质生物资源同步糖化发酵转化乙醇的研究较多,但是,麦草同步糖化发酵转化乙醇的最佳工艺条件还未确定。文中采用正交试验设计的方法,对在混合酶(纤维素酶Celluclast 1.5 1,β-葡萄糖苷酶Novozym 188)与酿酒酵母菌作用下,稀硫酸催化的蒸汽爆破麦草原料同步糖化发酵转化乙醇的工艺条件进行研究,详细讨论了反应温度、底物质量浓度、发酵液pH值、纤维素酶浓度对乙醇质量浓度和得率的影响。结果表明,工艺条件对乙醇质量浓度和得率的影响程度由高到低依次为:底物质量浓度、纤维素酶浓度、发酵液pH值、反应温度。最佳工艺条件为反应温度35℃,底物质量浓度100 g/L,发酵液pH值5.0,纤维素酶浓度30 FPU/g。在此条件下,随着反应时间的延长,乙醇质量浓度持续上升。反应72 h后,乙醇质量浓度和得率分别达到22.7 g/L和65.8%。