TS对青贮玉米秸秆与牛粪混合消化产气特性影响

为优化筛选青贮玉米秸秆与牛粪混合消化时的总固体浓度(TS),在37℃中温条件下,系统研究TS分别为10%、12%和14%时的产沼气性能、发酵液性质以及秸秆消化前后的理化特征。结果表明:青贮玉米秸秆与牛粪在TS为12%时的混合发酵产气效果优于10%和14%时,该条件下秸秆中纤维素和半纤维素的降解率分别为17.05%和45.13%。秸秆发酵前后的微观形貌和纤维素结晶度分析发现,秸秆的木质纤维结构变化明显,纤维素结晶度减小,且TS为12%时秸秆消化降解最严重,结晶指数最小。总之,适宜青贮玉米秸秆与牛粪混合发酵的TS值为12%,且消化过程中半纤维素最易于分解,但木质素几乎不被降解。     

混合菌群用于纤维素糖化和燃料酒精发酵的试验研究

采用刚果红纤维素平板法分别从田间腐烂的秸秆、潮湿地中的腐烂落叶内筛选出12株分解纤维素的菌株,分别进行了在不同温度、pH和时间条件下的羧甲基纤维素酶活(CMC)和滤纸酶活(FPA)的检测,筛选出了4株分解效率较高的菌株。采用正交实验研究了2株菌活性的主要影响因素,最终筛选出了2株产酶稳定的纤维素分解菌。采用扫描电镜,对菌株形貌进行了分析。应用2株纤维素分解菌和酵母菌混合菌种发酵的同时糖化发酵工艺,分别进行了单菌株和混合菌株的玉米秸秆糖化及燃料酒精发酵的试验研究,研究表明,混合菌群发酵后酒精产量为16g酒精/100g秸秆。     

黑曲霉AS0006预处理玉米秸秆产沼气研究

为了提高玉米秸秆与牛粪混合发酵的产气效率,文章对黑曲霉AS0006预处理后的玉米秸秆进行了研究,考察了不同预处理时间的玉米秸秆在混合厌氧发酵过程中的日产气量、累积产气量、TS和VS去除率以及木质纤维素去除率等发酵特性的变化情况。研究结果表明:黑曲霉AS0006对木质纤维素有较强的降解能力,玉米秸秆经黑曲霉AS0006预处理28 d后,纤维素、半纤维素和木质素的降解率分别为26.86%,11.93%和25.09%;经过黑曲霉AS0006预处理的玉米秸秆与牛粪混合发酵可以提高日产气量并缩短厌氧发酵周期,其中,预处理21 d后的玉米秸秆的产气高峰最大,为523.4 mL/d;经过黑曲霉AS0006预处理的玉米秸秆与牛粪混合发酵后, TS和VS去除率以及木质纤维素去除率均比未经预处理的玉米秸秆高。     

生物炭和乙醇对油菜秸秆沼气发酵特性的影响

对生物炭和乙醇提高油菜秸秆厌氧发酵沼气产率进行实验研究,探索不同乙醇浓度对中温和高温厌氧发酵沼气产率、木质纤维素降解和微生物菌群结构的影响。结果表明：生物炭和乙醇可促进沼气产率和纤维素降解。随着乙醇浓度的增大,沼气产率先增大后减小,3 g/L乙醇浓度时中温和高温发酵沼气产率最高,分别为219.3和240.5 mL/g。从木质纤维素降解来看,中温发酵组纤维素含量由预处理秸秆的54.00%降至18.69%～25.03%。测序结果显示乙醇浓度为3 g/L的中温发酵沼渣中厚壁菌门和拟杆菌门相对丰度最高,揭示了生物炭和乙醇促进油菜秸秆厌氧发酵产气的机制。     

低温纤维素降解菌系对沼气发酵过程中产酸、产气的影响

将本实验室一组稳定的低温兼性厌氧纤维素降解菌系X1接种到水稻秸秆和牛粪混合沼气发酵底物中,研究其在20℃低温沼气发酵过程中对产酸、产气的影响。结果表明,底物降解时主要产生乙酸、丙酸和丁酸,使pH值下降,处理组处理12 d时乙酸、总挥发性脂肪酸及甲烷含量分别为1.22,2.23 g/L和37.50%,对照组分别为0.47,0.81 g/L和28.50%。处理12 d后随着乙酸含量的逐渐下降,甲烷含量明显提高,15 d为50.20%,24 d达到67.60%,而对照仅为35%和43.30%;总产气量处理较对照提高76.81%。由此可见,菌系X1降解纤维素类物质时为甲烷合成提供了较多的前体物质,有效地提高了甲烷含量和产气量,使产气启动期提前。     

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.     

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.     

秸秆预处理白腐菌株的筛选及其对厌氧发酵的影响

农作物秸秆含有大量难降解的木质素,难于直接被厌氧微生物利用,降低了农作物秸秆的厌氧消化效率。该研究从8株白腐菌中筛选出1株产漆酶活力高的白腐菌株B-18,优化了该菌株的培养条件,确定适宜菌株B-18产漆酶的培养基为2%秸秆粉、2%蛋白胨、0.3%KH2PO4,0.15%MgSO4·7H2O,VB1 0.01g/L,1 000 mL蒸馏水、pH为5.0。利用该培养基进行B-18菌株培养,培养液中的漆酶活力单位为2.89 U。利用该菌株的液体培养物进行秸秆预处理,可促进秸秆中木质素的降解,这种作用加快了秸秆的厌氧发酵进程,可使秸秆产气时间提前4 d,产气量提高11.36%,容积产气率达到1.168 mL/(mL·d),原料产气率达到506.3 mL/g。该研究的进行对促进我国秸秆的沼气资源化利用具有重要的意义。     

牛粪、秸秆混合厌氧发酵制沼气研究

利用自行设计的恒温厌氧发酵装置研究了秸秆和牛粪配比、温度、初始pH对沼气发酵的影响。结果表明,发酵物秸秆和牛粪比例为1∶1时,发酵效果最好,累积总产气量为3 059 ml;温度为45℃时,发酵效果最好,累积总产气量为3 308 ml;初始pH为7.0时,发酵效果最好,累积总产气量为3 857 ml,甲烷含量为55.2%。     

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。     

拟康氏木霉和白腐菌混菌发酵处理稻草秸秆的研究

以拟康氏木霉3.3002(Trichoderma pseudokoningii)和白腐菌5.776(Phanerochaete chrysosporium)的混合菌发酵处理稻草秸秆,并对处理结果进行了试验研究.研究结果表明,当接人拟康氏木霉与白腐菌时间间隔为3 d.接种液体积比为2 ml:2 ml,氮源为0.3%(质量分数)的(NH4)2SO4,发酵时间为8 d时,稻草秸秆纤维索降解率和木质素降解率分别为40.38%和31.52%,比单独使用拟康氏木霉(纤维素和木质素降解率分别为24.62%,13.78%)或白腐菌(纤维素和木质素降解率分别为6.96%,20.06%)处理稻草秸秆的效果有显著提高.     

玉米秸秆预处理对厌氧发酵制氢影响的研究

为提高玉米秸秆的产氢能力,实验研究了蒸汽爆破预处理、硫酸预处理、氢氧化钠预处理、盐酸预处理和酸化(碱化)气爆预处理5种预处理方法对玉米秸秆发酵产氢能力的影响。结果表明,预处理可以将秸秆中相当一部分纤维素和半纤维素水解生成还原糖,其中质量分数为0.8%的H2SO4酸化汽爆预处理对秸秆的水解效果最好。在固-液比1∶10、H2SO4质量分数0.8%、保持微沸状态30min的处理条件下,秸秆的糖含量达到最大值24.57%,最大氢气产量为141mL/g。     

Measurement of the heat of smoldering combustion in straws and stalks by means of simultaneous thermal analysis

In order to investigate reaction heat of agro-stalks smoldering, wheat straw, corn stalk, cotton stalk, millet straw, sorghum stalk and sweet potato rattan powder were smoldered and pyrolyzed in a simultaneous thermal analyzer (STA). The samples were placed in a platinum crucible (?5 mm×5 mm) with a lid (with a ?1 mm hole) on a high-accuracy differential scanning calorimetry–heat capacity (DSC-cp) holder in the furnace of an STA and heated from 303 to 1073 K at a heating rate of 10 K min^?1. Sweeping gas with a flow rate of 25 ml min^?1 was air and nitrogen during smoldering and pyrolysis, respectively. Results showed that the heat emission characteristic of the smoldering process differed remarkably from the pyrolysis process. Based on the analysis of the DSC curves, oxidative polymer degradation heat and char oxidation heat were obtained from experimental data. It showed that the oxidative polymer degradation heat of the agro-stalks is more than 6.92 MJ kg^?1 consumed matter, higher than that of cellulose paper. And char oxidation heat is around 23 MJ kg^?1 consumed matter, similar to that of cellulose paper, but higher than that of cigarette. Total net heat emission of smoldering in STA was also obtained. These data can be used as reference data in analyzing smoldering of agro-stalks under similar conditions.     

农林废弃物成分分析及其综合利用前景展望

选取杉木木屑、红木木屑、桦木木屑、水稻秸秆、油菜秸秆和稻壳等6种农林废弃物为原料,采用化学定量分析法测定了生物质原料中纤维素、半纤维素和木质素的含量;采用电感耦合等离子体光谱法测定了生物质原料中的金属离子含量.在此基础上,探讨了各类农林废弃物综合利用的发展前景.     

采用热重与红外光谱联用研究玉米秸秆热解

采用热重与红外光谱联用技术(TG—FTIR),在升温速率为20℃/min下,对玉米秸秆各部分(秸秆皮、秸秆瓤、叶子及苞叶)的热解产物及析出过程进行了实验研究。实验结果表明,玉米秸秆各部分的热解产物主要为CO2、CO、CH4、H2O,同时含有少量的丙酸类物质;秸秆皮和秸秆瓤热解气体的析出呈单峰形状,而叶子和苞叶热解气体的析出呈双峰形状;玉米秸秆各部分的热解最大失重率对应的热解温度约为360～371℃,相差较小;对玉米秸秆的同一部分,主要热解产物的最大失重率对应的热解温度基本相同。     

Gasification efficiencies of cellulose,hemicellulose and lignin fractions of biomass in aqueous media by using Pt on activated carbon catalyst

The diversity in the chemical composition of lignocellulosic feedstocks can affect the conversion technologies employed for biofuel production. Aqueous-phase reforming (APR) activities of cellulose, hemicellulose and lignin components of lignocellulosic biomass materials were evaluated for production of hydrogen content gas mixture using platinum catalyst on activated carbon support. Wheat straw, an abundant by-product from wheat production and kenaf (Hibiscus cannabinus L.), an annual herbaceous plant growing very fast with low lodging susceptibility were used as lignocellulosics in the present study. The hydrolysates of cellulose fractions of biomass materials showed the best performance for gasification. The results indicated that hemicellulose isolated from kenaf was more sensitive to degradation and therefore, produced more gaseous products than that of wheat straw. The hemicellulose isolated from kenaf biomass left the lowest amount of ungasified solid residue in APR among other cellulose and hemicellulose materials studied. Lignin fractions of both biomass materials were not reactive in APR to produce hydrogen rich gas mixture.Gasification efficiencies of kenaf and wheat straw's hemicelluloses were also compared with xylans from beechwood and oat spelts which were commercially available as hemicellulosic fractions.Oat spelts xylan showed better reforming activity over the beechwood xylan.     

几种生物质热解反应动力学模型的比较

为了选择一个合适的生物质快速热解液化计算模型，分别对R．S．Miller模型和A．M．C．Janse模型进行分析和编程；在低升温速率下，将两种模型预测结果和小麦、玉米秸秆在热分析仪上的热解实验结果进行了对比；在高升温速率下，将这两种模型预测结果和由实验数据得出的平行一级反应模型预测结果进行了对比。对比结果表明：与A．M．C．Janse模型相比，R．S．Miller模型和热解实验较吻合，和平行一级反应模型预测结果相似，而A．M．C．Janse模型和实验及平行一级反应模型差别较大。对玉米、小麦秸秆快速热解液化进行计算时，建议选用R．S．Miller模型。     

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.     

氨化水饱和预处理麦秸厌氧消化产气性能的研究

试验以氨水为预处理试剂,研究在水饱和状态下,氨水添加量及负荷率对麦秸厌氧消化产气性能的影响。对氨化预处理前后麦秸的主要组分进行测定,采用傅立叶变换红外光谱(FTIR)对氨化水饱和预处理秸秆及秸秆中木素、纤维素和半纤维素的结构变化进行研究。结果表明,在3种负荷率下,氨化水饱和预处理后麦秸单位质量VS产气量分别提高了14%~23%,26%~36%和31%~45%。4%氨化预处理后的麦秸在65 g/L负荷率下获得最大377 mL/g的生物气产量。组分分析表明,氨化水饱和预处理可有效脱除39%~42%的半纤维素及11%~20%的纤维素,对木素含量影响较小。结构分析表明,氨化水饱和预处理可脱除细胞壁中的蜡质成分,使木素中部分官能团、纤维素中的氢键和糖苷键、半纤维素的部分氢键和糖单元之间的连接键发生断裂;从而使纤维素从木素的包裹中释放出来并发生溶胀,破坏其晶体结构;使半纤维素亲水性增强且更易于降解。这些秸秆内部结构的变化是提高麦秸厌氧消化产气性能的根本原因。