高浓度有机废水发酵法制取氢气技术

利用两相厌氧高浓度有机废水处理的产酸相制取氢气技术引起世界的普遍关注。介绍了厌氧发酵生物制氢系统的产氢机理、工艺流程与设计、工程控制参数等许多技术问题。认为发酵产氢微生物有丁酸型发酵、乙醇型发酵和甲酸裂解等3种产氢代谢途径。工艺设计以活性污泥的混合培养为主要形式,也发展了细菌的纯培养或辅之细胞固定化工艺。目前已经分离出肠杆菌属(Enterobacter)、梭状芽孢杆菌属(Clostridium)、柠檬酸菌属(Citrobacter)和新型乙醇型发酵产氢细菌等菌属的发酵产氢细菌,这些菌种除了可以纯培养制氢外,还可以进行投入反应系统进行生物强化和细胞固定化技术应用。乙醇型发酵生物制氢理论(双碳发酵产氢学说或理论)指导下发酵法混合培养生物制氢工艺已分别进行了小试和中试,并将进入生产示范工程阶段。     

光合细菌利用有机废水连续产氢的试验研究

为考察光合细菌连续性生物制氢过程中碳源浓度、水力停留时间等因素对连续运行稳定性能和制氢量的影响,通过改变碳源浓度和水力停留时间来测定产氢量以及产氢率,确定最佳的连续运行条件。结果表明:光合细菌利用含糖废水为基质进行连续性生物制氢过程中,在最佳温度为30℃、最佳光照强度为3 000 Lux的情况下,且当葡萄糖质量浓度为12 g/L,水力停留时间为72 h时,产氢效率最高,连续产氢速率达45 m L/h。     

底物与pH值对菌株Clostridium R33 sp.nov.产氢能力的影响

引言生物制氢技术利用高浓度有机废水或其他生物质能制取氢气,反应条件温和,具有开发新能源、节省能量消耗及净化环境的重要意义,其工艺实质是产氢产酸发酵细菌对有机物质的发酵过程,将有机物质分解为有机酸的同时释放出发酵气体H_2和CO_2。由此可见,研究影响产氢细菌的关键因素,对于提高细菌的产氢能力具有十分重要的意义。Jung等研究了底物浓度对Citrobacter sp.Y19产氢能力的影响,Fang等研究了pH值对     

一株发酵产氢细菌对戊糖的氢气转换及产氢机理

引言制约发酵法生物制氢进一步发展的关键问题是,如何找到来源广泛价格低廉的底物。纤维素、半纤维素和木质素是农作物秸秆的主要组成成分,其酶解液主要由五碳糖、六碳糖和简单多聚糖组成。因此研究和筛选能够利用五碳糖产氢发酵的微生物及其产氢规律,对于扩展底物范围具有重要意义。目前,国内外学者大都集中研究利用已糖(葡萄糖)的发酵产氢上,尚未发现有关利用五碳糖发酵产氢的报道。本文试图通过产氢细菌发酵几种五碳糖来探讨产氢的可能性和产氢机理,为发     

玉米秸秆生物产氢菌的分离培养及鉴定研究

以牛粪为菌种来源,利用玉米秸秆进行厌氧发酵产氢实验,在产氢效果达160 mL/h,秸秆产氢能力225 mL/g的最佳状态下,从实验中提取发酵菌液进行细菌的分离培养,并对产氢效果最好的R-3菌种进行生理生化试验研究和初步鉴定,确定产氢细菌为Clostridium sp.Fanp2.     

纯培养生物制氢的分批培养工艺的建立与调控

氢气是一种理想的能源,具有转化率高、可再生和无污染等优点。试验利用厌氧发酵技术分离培养产氢细菌,并对产氢细菌进行理化分析。在乙醇型发酵的产氢原理上,以蔗糖作为产氢微生物的培养基,通过间歇培养的方式研究产氢微生物的产氢特性,采取分批培养的方式来研究纯培养生物制氢工艺。纯培养生物制氢工艺的主要工程控制对策为:按反应溶液体积的2%接种新鲜产氢细菌种子培养液,底物浓度采用20%,反应启动时间63 h,温度35℃。     

发酵制氢废液的微生物电解池产氢

采用单室微生物电解池（MEC）反应器为实验装置,通过预处理技术强化发酵制氢废液中乙酸的积累,并将该发酵废液作为底物,考察了以废液中累积的乙酸作为主要电子供体、碳布为阳极、涂布有Ni纳米颗粒的不锈钢网为催化阴极的产氢效果。结果表明,在MEC中,以预处理的发酵制氢废液积累的乙酸为底物,最高产氢率可达(1.31±0.04) m3H2/(m3?d)和(2.78±0.11) mLH2/mgCOD,同时可获得138.6%±3.1%的能量效率和99.0%±0.3%的COD去除率。实验表明,利用MEC可将发酵末端产物进一步降解,从而减弱了“发酵障碍”现象,实现了治污和产能的统一。     

生物制氢研究进展(Ⅰ)产氢机理与研究动态

阐述了7类生物制氢系统的产氢机理、影响因素以及提高产氢率和产氢量的方法,介绍了国外最新的研究进展。光发酵生物制氢技术和厌氧发酵生物制氢技术是研究的热点,而厌氧发酵由于产氢效率较高而成为最具潜力的生物制氢技术之一。光合-发酵杂交技术不仅减少了所需光能,而且增加了氢气产量,同时也彻底降解了有机物,使该技术成为生物制氢技术的发展方向。     

发酵产氢细菌的紫外线诱变筛选高产菌株

引言厌氧发酵生物制氢主要依靠细菌的发酵产氢,而如何高效地利用细菌发酵产氢是一个非常重要的问题,高效厌氧产氢细菌的诱变选育研究就是为了找到高效产氢细菌并投入生产。环境微生物的育种仍是以使用物理诱变、化学诱变或两者复合诱变的诱变育种作为最主要的方法。通过诱变育种能达到以下几个目的:(1)提高氢气的产率;(2)改善菌种特性,提高产品质量;(3)简化工艺条件;(4)开发新品种,通过选择几种具有代表性     

金属纳米颗粒辅助木质纤维素暗发酵生物制氢的研究进展

通过文献计量学分析表明暗发酵制氢是目前研究最热门的生物制氢方法,Fe、Ni、Co、Ag等金属纳米颗粒作为该领域研究热点可改善暗发酵制氢存在底物转化率与产氢效率均有待提高的难题。介绍了金属纳米颗粒的特点、生物相容性及其与酶、微生物细胞的作用机理,进一步从促进木质纤维素水解影响产氢、对水解酶的固定化影响产氢、提高氢化酶活性影响产氢、调控发酵微生物细胞代谢和促进细胞电子传递影响产氢、改善微生物群落结构影响多菌群协同产氢等几个方面对典型金属纳米颗粒辅助木质纤维素暗发酵产氢的研究现状进行综述,并对金属纳米颗粒应用于暗发酵产氢存在的难点及前景方向进行了展望。     

ACR在不同进水COD浓度下的产氢性能与菌群结构

以稀释糖蜜为底物,通过厌氧接触式发酵制氢反应器(ACR) 的启动和运行,考察了ACR在不同进水COD浓度下的运行特性。结果表明,当HRT= 6 h,进水COD浓度从 7000 mg·L^-1提升至11000 mg·L^-1时,反应器仍能稳定运行,并维持乙醇型发酵类型。随着底物浓度的增加,系统的比产氢速率从COD 7000 mg·L^-1时的2.43 m³·(m³·d)^-1提高到COD11000 mg·L^-1时的3.51 m³·(m³·d)^-1,而活性污泥的比产氢速率在COD 为9000 mg·L^-1时最高,为10.71 mol H₂·(kg VSS·d)^-1。聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)分析结果表明,产氢发酵产乙醇菌群为ACR系统中的主要产氢功能菌群,且随着进水COD浓度的增加,以Ethanoligenens harbinense YUAN-3为代表的产氢菌群的优势度显著增强,但丙酸发酵菌属Propionicimonas sp. F6也开始富集。     

Biolog鉴定产氢发酵细菌及其产氢能力的研究

采用厌氧培养技术,从厌氧活性污泥中分离得到一株产氢发酵细菌。利用B iolog自动菌种鉴定仪对该产氢发酵细菌作了鉴定分析,确定了其在细菌学上的分类地位,新分离菌株C lostridium papyrosolvens为生物制氢分离鉴定纯产氢菌种提供了指导,该菌株为专性厌氧杆菌,蔗糖发酵液体末端主要产物为乙醇、乙酸,气相产物为H2和CO2,代谢特征为乙醇型发酵,在pH 6.0和36℃条件下最大产氢量为72 mL H2/g蔗糖。     

固定化细胞技术发酵产氢的应用研究

微生物发酵产氢的固定化细胞技术与其非固定化细胞技术相比,前者具有很大的优越性,能显著提高发酵系统的产氢量。对微生物发酵产氢固定化细胞的制备方法及其应用载体进行了介绍,分析了国内外固定化细胞技术在厌氧产氢中的最新进展,指出了固定化细胞技术发酵产氢存在的问题,并对其发展进行了探讨。     

玉米秸秆厌氧发酵制氢的实验研究

在小试和批试实验结果的基础上,以牛粪堆肥作为菌种来源,玉米秸秆作为发酵底物,进行了30 L规模的放大实验研究。主要考察了菌种接种龄对产氢效果的影响、最佳初始有机负荷、反应过程中菌种的生长曲线及底物的代谢特征,并有液相末端发酵产物确定发酵类型。结果表明：在实验条件下,菌种的最佳接种龄为18 h,最佳初始启动负荷为8 105 mg/L,秸秆的最大产氢能力可达到220 mL/g,COD的去除率可达到57%,稳定期细胞浓度维持在3.8 g/L左右,发酵类型为乙醇型发酵。     

Toxicity tolerance of Fusarium oxysporum towards inhibitory compounds formed during pretreatment of lignocellulosic materials

BACKGROUND: During the pretreatment of lignocellulosic materials, molecules such as carboxylic acids, furan derivatives and phenolic compounds, which inhibit the growth and ethanol fermentation by bacteria, fungi and yeasts, are produced. The present work determines the tolerance levels of the C5, C6 fermenting fungus Fusarium oxysporum, towards individual model inhibitory compounds on aerobic growth, on lignocellulolytic activities and on fermentative performance. RESULTS During the growth stage, maximum biomass production was more affected than the specific growth rate by the presence of inhibitors. The presence of high concentrations of inhibitors resulted, in most cases, in prolongation of the lag phase. The fermentative performance of F. oxysporum was significantly inhibited by carboxylic acids, while the lignocellulolytic activities were affected to a lesser extent. CONCLUSION: The toxicity tolerance of fF. oxysporum was high enough for aerobic growth in the presence of significant concentrations of inhibitors, which in most cases were higher than those generated from various treatments of lignocellulosic materials, while its fermentative performance was relatively more affected by the presence of inhibitors. The decrease of ethanol production in the presence of weak organic acids could be the main obstacle to the application of F. oxysporum in large‐scale bioconversion processes of hydrolysates containing inhibitors. Copyright © 2010 Society of Chemical Industry     

污水厂污泥厌氧消化产短链脂肪酸研究进展

污泥厌氧消化产短链脂肪酸是实现污泥资源化的重要途径,短链脂肪酸不仅是产甲烷的底物、污水脱氮除磷的碳源,而且可以作为原料产生一系列高附加值的产品。本文介绍了污泥厌氧消化产有机酸的机理,重点阐述了污泥性质、温度、pH值、碳氮比（C/N）、水力停留时间（HRT）和固体停留时间（SRT）等影响污泥厌氧消化产酸的主要因素及研究进展,指出这些因素通过改变底物性质、微生物活性及二者接触反应时间等对产酸过程产生影响,其中温度和pH值是研究热点,目前大多数研究者认为高温和碱性条件更有利于污泥产酸。此外,还论证了这些影响因素对于实现污泥产酸最大化的重要意义,提出各因素之间的相互关系以及通过调控温度、pH值、碳氮比等发酵影响因素来控制产酸类型是今后值得研究的方向。     

A review on fermentative hydrogen production from dairy industry wastewater

Hydrogen (H₂) is one of the most promising alternative fuel sources for satisfying future energy demand, and fermentative hydrogen production is advantageous over other processes. In recent decades, considerable research has been conducted on H₂ production from carbohydrate‐rich materials since it is a cost‐effective approach and has the ability to generate intensive renewable energy from organic wastes. Dairy wastewater is a high volume industrial wastewater and with its immense carbohydrate content is an attractive candidate for sustainable fermentative H₂ production. The present paper provides comprehensive evaluation of recent reports on fermentative H₂ production from dairy wastewater. Important effective parameters and current bioreactor technologies for H₂ production from dairy wastewater are discussed. © 2014 Society of Chemical Industry     

Enhancing the Production of Light Olefins by Catalytic Cracking of FCC Naphtha over Mesoporous ZSM-5 Catalyst

The enhanced production of light olefins from the catalytic cracking of FCC naphtha was investigated over a mesoporous ZSM-5 (Meso-Z) catalyst. The effects of acidity and pore structure on conversion, yields and selectivity to light olefins were studied in microactivity test (MAT) unit at 600 °C and different catalyst-to-naphtha (C/N) ratios. The catalytic performance of Meso-Z catalyst was compared with three conventional ZSM-5 catalysts having different SiO₂/Al₂O₃ (Si/Al) ratios of 22 (Z-22), 27 (Z-27) and 150 (Z-150). The yields of propylene (16 wt%) and ethylene (10 wt%) were significantly higher for Meso-Z compared with the conventional ZSM-5 catalysts. Almost 90% of the olefins in the FCC naphtha feed were converted to lighter olefins, mostly propylene. The aromatics fraction in cracked naphtha almost doubled in all catalysts indicating some level of aromatization activity. The enhanced production of light olefins for Meso-Z is attributed to its small crystals that suppressed secondary and hydrogen transfer reactions and to its mesopores that offered easier transport and access to active sites.     

Production of hydrogen by steam reforming of glycerin over alumina-supported metal catalysts

Use of biodiesel and its production are expected to grow steadily in the future. With the increase in production of biodiesel, there would be a glut of glycerin in the world market. Glycerin is a potential feedstock for hydrogen production because one mol of glycerin can produce up to four mols of hydrogen. However, less attention has been given for the production of hydrogen from glycerin. The objective of this study is to develop, test and characterize promising catalysts for hydrogen generation from steam reforming of glycerin. Fourteen catalysts were prepared on ceramic foam monoliths (92% Al₂O₃, and 8% SiO₂) by the incipient wetness technique. This paper discusses the effect of these catalysts on hydrogen selectivity and glycerin conversion in temperatures ranging from 600 to 900 °C. The effect of glycerin to water ratio, metal loading, and the feed flow rate (space velocity) was analyzed for the two best performing catalysts. Under the reaction conditions investigated in this study, Ni/Al₂O₃ and Rh/CeO₂/Al₂O₃ were found as the best performing catalysts in terms of hydrogen selectivity and glycerin conversion. It was found that with the increase in water to glycerin molar ratio, hydrogen selectivity and glycerin conversion increased. About 80% of hydrogen selectivity was obtained with Ni/Al₂O₃, whereas the selectivity was 71% with Rh/CeO₂/Al₂O₃ at 9:1 water to glycerin molar ratio, 900 °C temperature, and 0.15 ml/min feed flow rate (15300 GHSV). Although increase in metal loading increased glycerin conversion for both catalysts, hydrogen selectivity remained relatively unaffected. At 3.5 wt% of metal loading, the glycerin conversion was about 94% in both the catalysts.