一株纤维素降解新菌种发酵玉米秸杆的生物产氢特性研究

试验从连续流发酵产氢反应器(ZL92114474.1)中分离筛选出一株高效纤维素降解产氢细菌Clostridium sp.X9.X9利用微晶纤维素(MC)作为发酵产氢底物,得到最大单位体积产氢量(YH2)、比产氢率(YH2/s)和纤维素降解率分别为780 mL H2/L-culture、5.1 mmol H2/g-cellulose和69.6%.采用酸、碱、氨水和酸化汽爆方式预处理玉米秸秆,结果表明,酸化汽爆方式可以获得最佳的预处理效果.X9利用酸化汽爆玉米秸秆(cSES)发酵产氢的YH2、YH2/8和纤维素降解率分别达到730 ml H2/L-culture、4.3 mmol H2/g-cellulose和64%.这说明新菌种X9在利用玉米秸秆类生物质纤维素发酵产氢方面具有很好的应用潜力.     

一株纤维素降解新菌种发酵玉米秸秆的生物产氢特性研究

试验从连续流发酵产氢反应器（ZL92114474．1）中分离筛选出一株高效纤维素降解产氢细菌Clostridilan sp．X9。X9利用微晶纤维素（MC）作为发酵产氢底物,得到最大单位体积产氢量（YH2）、比产氢率（YH2／s）和纤维素降解率分别为780mL H2／L-culture、5．1mmol H2／g-cellulose和69．6％。采用酸、碱、氨水和酸化汽爆方式预处理玉米秸秆,结果表明,酸化汽爆方式可以获得最佳的预处理效果。x9利用酸化汽爆玉米秸秆（cSES）发酵产氢的YH2、YH2／s和纤维索降解率分别达到730mL H2／L-culture、4．3mmol H2／g-cellulose和64％。这说明新菌种X9在利用玉米秸秆类生物质纤维素发酵产氢方面具有很好的应用潜力。     

一株纤维素降解新菌种发酵玉米秸秆的生物产氢特性研究

从连续流发酵产氢反应器(ZL9211474.1)中分离筛选出一株高效纤维素降解产氢细菌Clostridium.sp.X9,X9利用微晶纤维素(MC)作为发酵产氢底物,得到最大单位体积产氢量(YH2)、比产氢率(YH2/s)和纤维素降解率分别为780mL H2/L-culture、5.1mmol H2/g-cellulose和69.6%.采用酸、碱、氨水和酸化汽曝4种方式预处理玉米秸秆,结果表明,酸化汽曝方式可以获得最佳的预处理效果.X9利用酸化汽曝预处理的玉米秸秆发酵产氢的YH2、YH2/s和纤维素降解率分别达到730mL H2/L-cuhllre、4.3mmol H2/g-ceulllose和64.0%.这说明新菌种X9在利用玉米秸秆类生物质纤维素发酵产氢方面具有很好的应用潜力.     

稀酸预处理玉米秸秆条件优化的试验研究

采用稀硫酸对玉米秸秆进行预处理,采用DNS法测定玉米秸秆水解液中还原糖的含量,对水解温度、水解时间、稀硫酸质量分数、固液质量比4个因素进行单因素试验分析,再通过正交试验对预处理条件进行优化.试验结果表明,最佳预处理条件:水解温度为121℃,水解时间为1 h,稀硫酸质量分数为0.6%,固液质量比为10%.     

碱和双氧水预处理玉米秸秆的试验研究

研究了在5%NaOH中加入不同质量分数的双氧水时,对玉米秸秆的预处理效果;在预处理后的玉米秸秆中加入纤维素酶,考察此时酶解还原糖得率随预处理程度的变化;对浸泡时间、双氧水浓度、固液比3个因素进行单因素试验。试验结果表明,质量分数为2.5%的浓度下,糖得率最大;在2.5%H2O2浸泡24 h,固液比对酶解糖化几乎没有影响;当浸泡时间为24,72,96 h时,糖得率相差甚微。设计正交试验对预处理的条件进行优化,分析预处理玉米秸秆的各因素,以木质素去除率为基准参数,得到水解木质纤维素的适宜预处理条件:5%NaOH下加入质量分数为2.5%的双氧水,浸泡时间为72 h,固液比为1∶20。预处理后木质素的去除率为61.52%;加入纤维素酶酶解,还原糖得率为39.30%。     

玉米秸秆酶解与厌氧发酵产氢实验研究

以粒度小于0.088 mm秸秆粉的酶解液为底物与热预处理活性污泥(其中TS%为6.77%,VS%为47.90%,COD为36.665 g/L)进行厌氧发酵产氢实验,以累积产氢量和产氢速率为考察指标,研究不同热预处理(100℃水浴)时间、初始p H值、酶解液浓度、发酵温度对厌氧发酵产氢的影响,并利用修正的Gompertz方程对产氢过程进行回归分析,优化出最佳玉米秸秆酶解液厌氧发酵产氢的工艺参数。结果表明:活性污泥利用玉米秸秆酶解液进行厌氧发酵产氢时,当活性污泥热预处理时间为15 min、初始p H值为5.0、玉米秸秆粉酶解液浓度为22.34 mg/m L、发酵温度为40℃时,产氢效果最佳,此时最大累积产氢量达到653.98 m L,最大产氢速率为15.89 m L/h。     

底物质量浓度对玉米秸秆同步糖化生物制氢的影响

利用HAU-M1光合细菌对玉米秸秆同步糖化生物制氢工艺进行实验研究,提出了同步糖化生物制氢工艺中玉米秸秆底物质量浓度与pH值、还原糖质量浓度、氢气体积分数和累积产氢量等因素之间的相关关系,探讨了底物质量浓度对玉米秸秆同步糖化生物制氢工艺的影响规律。实验结果表明:当玉米秸秆底物质量浓度为25g/L时,玉米秸秆同步糖化生物制氢工艺的累积产氢量达到最高,为186mL;当玉米秸秆底物质量浓度为15g/L时,玉米秸秆同步糖化生物制氢工艺的氢气体积分数达到最高,为48%;玉米秸秆同步糖化制氢工艺的产氢高峰期为12~48h,48h后逐渐停止产氢,可为进一步优化和完善以生物质为基质的同步糖化生物制氢工艺理论与技术提供科学参考。     

玉米秸秆破碎度与酶解光合制氢的关系研究

以玉米秸秆为原料,利用微化破碎和酶水解结合的预处理方法,采用自制的光合制氢实验装置,进行不同破碎度对酶解光合制氢过程的影响实验研究,结果表明:当玉米秸秆破碎度为53~61μm时,最大比产氢速率约为26.4mL/(L·h),光能转化率达到25%,底物能量转化率约为5.3%,既具有较高的累计产氢量,又保证了较好的光能转化率和底物能量转化率,产氢综合效果最好。     

酸化温度对玉米秸秆厌氧水解酸化性能的影响

文章研究了不同酸化温度(35,40,45℃)对玉米秸秆厌氧水解酸化性能的影响。研究结果表明:酸化温度对玉米秸秆水解酸化的程度以及产酸代谢类型有显著影响;当酸化温度为40℃时,玉米秸秆水解酸化产生的可溶性化学需氧量(SCOD)和挥发性脂肪酸(VFAs)的浓度最高,产生的气体以H_2和CO_2为主;酸化相的pH值为5.14～5.51,VFAs中乙酸和丁酸含量之和占VFAs总量的85.2%～91.4%,此时酸化相进行的是有利于甲烷化的丁酸型发酵;     

稀硫酸预处理玉米秸秆条件的优化研究

对稀硫酸预处理玉米秸秆优化工艺条件进行了试验研究,在考察温度、时间、稀硫酸质量分数、固液质量比和玉米秸秆粒度5个单因素对预处理效果影响的基础上,采用响应面分析法对预处理条件进行优化,建立了以戊糖得率为响应值的二次回归方程模型,得到最佳预处理条件为水解温度120℃,水解时间75 min,稀硫酸质量分数1.0%,固液质量比1∶15,玉米秸秆颗粒为40目。此条件下,理论预测戊糖得率为65.018%,试验验证戊糖得率为64.37%,与预测值接近,说明预测模型可靠性较高,可应用于稀酸预处理条件的优化。     

New process of maize stalk amination treatment by steam explosion

Amination treatment of straw proceeds slowly at the low environmental temperatures. Although the aqueous ammonia has a relatively good effect, it has high volatility and an irritant odor. Steam explosion has the advantage of short reaction time, but it cannot improve the nitrogen content of the straw for animal feed. A new process combined with the two methods for maize stalk pretreatment was studied to improve its nutritive value. The results showed that nitrogen sources coupled with steam explosion modified the treated materials. Except for urea, other nitrogen sources promoted the degradation of hemicellulose and the increase of the soluble sugars content. Decrease of hemicellulose treated with 5% (NH₄)₂SO₃ was highest (58.0%), but no significant changes were detected in cellulose and lignin content using chemical methods after nitrogen source addition. Compared with steam explosion pretreatment, amination by steam explosion increased the nitrogen content of maize stalk. The highest total nitrogen content (2.30%) was obtained by adding urea. The treatment of 5% (NH₄)₂SO₃ led to the highest retention of added nitrogen (84.0%) and 15% NH₄OH led to the lowest percentage of retention (18.1%). Amination by steam explosion effectively increased the potential digestibility of DM, and the maximum digestibility value (71.2%) was obtained when 5% (NH₄)₂SO₃ was added. Amination by steam explosion shortened the amination time and was a rapid and effective method of improving the nutritive value of straw.     

Screening of steam explosion conditions for glucose production from non-impregnated wheat straw

The conversion of wheat straw to fermentable sugar for bioethanol production typically involves a thermal pretreatment step, followed by enzymatic hydrolysis. In this study we have investigated the effect of steam explosion parameters on wheat straw digestibility using a newly designed steam explosion unit and a process without acid impregnation. The wheat straw was steam pretreated using 18 different conditions in the temperature range of 170-220 °C and the resulting material was used directly (i.e. without washing) for enzymatic hydrolysis and fermentation in either a separate hydrolysis and fermentation (SHF)-type or a simultaneous saccharification and fermentation (SSF)-type set-up. Maximum glucose yields upon enzymatic hydrolysis were obtained after pretreatment at 210 °C for 10 min and yields were similar at harsher conditions. Xylose yields increased with temperature and residence time up to 190 °C, but decreased at harsher pretreatment conditions since these led to xylan degradation and concomitant production of furfural. In an SHF-type set-up ethanol formation did not follow enzymatic glucose release and was inversely correlated with furfural levels. An SFF-type set-up displayed a straightforward correlation between the expected amount of released glucose and the ethanol yields. The highest saccharification yields corresponded to about 90% of the cellulose in the substrate. Overall, this study shows that steam explosion without an acid catalyst is a good pretreatment method for saccharification of wheat straw. Optimal steam explosion conditions need to be a compromise between sugar accessibility and sugar degradation.     

榨糖收贮模式玉米秸秆蒸汽爆破预处理条件优化

使用蒸汽爆破法处理榨糖收贮玉米秸秆榨渣,观察不同蒸汽爆破压力和维压时间下纤维素、半纤维素、木质素（三大素）及纤维素酶水解得率的变化。榨渣三大素含量不同程度下降,半纤维素下降最多,其次是木质素,而纤维素下降最少。处理后进行的水解实验显示压力与维压时间的增加会导致纤维素水解酶得率有所提高,但压力增加对纤维素水解酶影响较小,维压时间对纤维素水解酶的影响较为突出。考虑经济成本的前提下选择1.2 MPa,10 min维压时间为最佳条件,其中纤维素含量为34.42%、半纤维素4.01%、木质素17.09%及纤维素酶水解得率为68.3%。     

秸秆混煤燃烧对SO2排放的影响

利用循环流化床实验平台,分析秸秆混煤燃烧对SO2排放的影响。将秸秆与贫煤按不同质量比制成混合燃料,在流化床锅炉中燃烧,采集炉温及烟气中SO2浓度等数据进行分析。结果表明,当燃烧温度恒定时,SO2的排放量随着燃料中秸秆所占比重增加而降低;当燃料中秸秆所占比重恒定时,SO2的排放量随着燃烧温度的升高而增加。     

Pretreatment and fractionation of barley straw using steam explosion at low severity factor

Agricultural residues represent an abundant, readily available, and inexpensive source of renewable lignocellulosic biomass. However, biomass has complex structural formation that binds cellulose and hemicellulose. This necessitates the initial breakdown of the lignocellulosic matrix. Steam explosion pretreatment was performed on barley straw grind to assist in the deconstruction and disaggregation of the matrix, so as to have access to the cellulose and hemicellulose. The following process and material variables were used: temperature (140–180 °C), corresponding saturated pressure (500–1100 kPa), retention time (5–10 min), and mass fraction of water 8–50%. The effect of the pretreatment was assessed through chemical composition analysis. The severity factor R_o, which combines the temperature and time of the hydrolytic process into a single reaction ordinate was determined. To further provide detailed chemical composition of the steam exploded and non-treated biomass, ultimate analysis was performed to quantify the elemental components. Data show that steam explosion resulted in the breakdown of biomass matrix with increase in acid soluble lignin. However, there was a considerable thermal degradation of cellulose and hemicellulose with increase in acid insoluble lignin content. The high degradation of the hemicellulose can be accounted for by its amorphous nature which is easily disrupted by external influences unlike the well-arranged crystalline cellulose. The carbon content of the solid steam exploded product increased at higher temperature and longer residence time, while the hydrogen and oxygen content decreased, and the higher heating value (HHV) increased.     

The steam explosion pretreatment and enzymatic hydrolysis of wheat bran

This article focused on the saccharification of wheat bran with steam explosion pretreatment and enzymatic hydrolysis. Wheat bran was pretreated with steam explosion to improve saccharification with enzymatic hydrolysis, and a maximum reducing sugar yield reached 194.6 mg/g (dry), which was about 63% higher than that of the wheat bran without pretreatment. Electronic microscope scanning and infrared spectroscopy showed that steam explosion with low pressure destroyed the structure and promoted the enzymatic hydrolysis of wheat bran effectively. Further, higher pressure produced harmful substances to hinder the saccharification and subsequent fermentation rather than increase saccharification ability of blasting bran.     

Comparative net energy ratio analysis of pellet produced from steam pretreated biomass from agricultural residues and energy crops

A process model was developed to determine the net energy ratio (NER) for the production of pellets from steam pretreated agricultural residue (wheat straw) and energy crops (i.e., switchgrass in this case). The NER is a ratio of the net energy output to the total net energy input from non-renewable energy sources into a system. Scenarios were developed to measure the effects of temperature and level of steam pretreatment on the NER of steam pretreated wheat straw and switchgrass pellets. The NERs for the base case at 6 kg h⁻¹ are 1.76 and 1.37 for steam-pretreated wheat straw and switchgrass-based pellets, respectively. The reason behind the difference is that more energy is required to dry switchgrass pellets than wheat straw pellets. The sensitivity analysis for the model shows that the optimum temperature for steam pretreatment is 160 °C with 50% pretreatment (i.e. 50 % steam treated material is blended with the raw biomass and then pelletised). The uncertainty results for NER for steam pretreated wheat straw and switch grass pellets are 1.62 ± 0.10 and 1.42 ± 0.11, respectively.     

市政污泥流化床掺烧生物质的NO与SO2排放特性研究

为了探究市政污泥燃烧过程中的气态污染物排放特性,在30 kW鼓泡流化床实验台上进行了市政污泥的燃烧实验,研究燃烧温度、二次风率、秸秆掺混比等参数对气态污染物排放特性的影响。结果表明：燃烧温度的升高会显著提高NO与SO₂的排放;提高二次风率使NO排放浓度减少,SO₂排放浓度增加;由于生物质中较低的N、S含量以及生物质与污泥燃烧的协同作用,污泥掺烧生物质能够有效地减少NO与SO₂的排放;秸秆占比由0提升至40%,NO由289 mg/m³下降至140 mg/m³,而SO₂排放浓度也从3 949 mg/m³下降至1 725 mg/m³;污泥掺烧秸秆时,NO与SO₂的整体排放特性与污泥单独焚烧相似,掺烧秸秆能够加快整体的燃烧速率,并加强燃烧气氛的氧化性,进而影响气态污染物的排放。     

废甲醇催化剂综合利用技术进展

甲醇的产能在所有化工产品中仅次于乙烯和合成氨,每年产生的废甲醇催化剂数量巨大。合成甲醇催化剂经历了锌铬高压催化剂、铜基催化剂、合金催化剂及其他非铜基催化剂3个发展阶段,目前在工业中应用的主要为铜基催化剂,此类废催化剂的回收主要围绕Cu和Zn的分离及回收展开。回收工艺可分为酸浸、氨浸和酸浸-电解工艺。废催化剂预处理的关键是在800～1000℃进行焙烧,其目的一是去除有机物,二是脱硫,三是使其中的氧化铝或Cr2O3转化为酸难溶的晶型,四是使金属铜或氧化亚铜转化为氧化铜。预处理后的废催化剂可通过H2SO4酸浸-Zn还原法回收活性ZnO和CuSO4·5H2O,通过H2SO4酸浸-SO32-还原法回收活性ZnO和CuCl,通过HNO3酸浸-Zn还原法制备硝酸盐,通过H2SO4-NHO3联合酸浸法制备胆矾和铝铵矾;通过NH4＋铬合氨浸回收CuCl和活性ZnO,通过NH4＋-NH3复合氨浸回收Cu2O和ZnO;通过H2SO4酸浸-电解回收单质Cu。此外,还可以被制成微肥或作为脱硫剂使用。     

Synergistic mechanism of steam explosion combined with fungal treatment by Phellinus baumii for the pretreatment of corn stalk

Pretreatment was the essential step for industrial application of lignocellulosic biomass. Combination of steam explosion and fungal treatment was conducted, and synergistic mechanism of the combined pretreatment was evaluated in terms of pore size distribution, crystallinity index, chemical compositions and enzymatic hydrolysis. The results showed that steam explosion destroyed the rigid structure of corn stalk, increased pore size and porosity, and exposed crystalline component of cellulose. Steam explosion broke the lignin-carbohydrate-complex structure of lignocellulosic biomass and facilitated the fungal treatment. Phellinus baumii could selectively degrade 34.7% and 36.58% of lignin for 1.4 MPa and 1.7 MPa steam-exploded corn stalk, respectively. As a result, the highest glucose yield of corn stalk pretreated by the condition of 1.7 MPa steam explosion associated with 21 d P. baumii reached 313.31 g kg⁻¹, which was 2.88 and 1.32 times higher than that of the untreated corn stalk and the 1.7 MPa steam-exploded corn stalk, respectively. The combined pretreatment enhanced the enzymatic hydrolysis, which was a promising technology that might be explored as alternative to the existing pretreatment.