秸秆类木质纤维素原料厌氧发酵产沼气研究

介绍了以秸秆为主要原料的好氧预处理过程及厌氧干发酵工艺的试验结果.在预处理过程中,加入好氧降解菌种使木质纤维素降解率提高到50%.当发酵温度为(35±2)℃,,TS含量为20%,秸秆与猪粪配比为7:3时,原料滞留期为40 d,平均容积产气率为0.8～1 m3/(m3·d),甲烷含量为65%以上.     

生物气源岩中原核生物改性指标与评价新方法

在调查原核生物化学分配作用对有机质饱和烃中主要生物标志化合物和咔唑类化合物分布产生影响的基础上,借助微生物学领域的研究成果,对柴达木盆地东部和松辽盆地北部两地区泥岩样品进行地球化学分析.确定可利用规则甾烷/17α(H)-藿烷值、C35αβ-升藿烷指数、奥利烷指数、BNH/TNH等参数及(C28-C31)-烷基甾烷丰度的变化对未熟-低熟有机质中细菌和古菌活性进行评价.在淡水-咸水沉积域的强厌氧环境中,生气母质的有机氮含量与产甲烷八叠球菌属的固氮作用有关,来自原生质的含氮杂环化合物在产甲烷条件下,被产甲烷菌伙伴所降解,因此在优质生气母质中,C0-C3咔唑和苯并咔唑化合物的总含量很低,比其他类型样品低1～2个数量级左右.图6表3参32     

Expansion characteristics of an anaerobic fluidized bed reactor with internal biogas production

More realistic dynamic bed‐expansion experiments using a three‐phase anaerobic fluidized bed reactor (AFBR) with and without internal biogas production were conducted for the establishment of correlation equations for the mean volume ratio of wakes to bubbles (k). A predictive model was also developed for the expansion characteristics of the three‐phase AFBR with internal biogas production. The predicted bed‐expansion heights (H_GLS) deviated by only ±10% from the experimental measurements for the three‐phase AFBR. According to the modeling results, if a three‐phase AFBR is loaded into a carrier with low specific gravity (dry density of carrier, ρ_md = 1.37 g cm^?3; wet density of carrier, ρ_mw = 1.57 g cm^?3) and operated at a high superficial liquid velocity (u_l = 4.0 cm s^?1), the ratio of H_GLS to H_LS at a high superficial gas velocity (u_g = 1.5 cm s^?1) can reach as high as 271%. A higher fluidized‐bed height has a greater effect on the bed‐expansion behavior because of the decrease in liquid pressure (surrounding gas bubbles) along the fluidized‐bed height. From parametric sensitivity analyses, H_GLS is most sensitive to the parameter reactor width (X), especially within a small ΔX/X₀ range of ±10%; sensitive to ρ_mw, diameter of the carrier, ρ_md and total mass of carrier and least sensitive to u_l, biofilm thickness and u_g. Copyright © 2005 Society of Chemical Industry     

Anaerobic digestion of seaweed for biogas: A kinetic evaluation

A kinetic study of biogas production in batch digesters by anaerobic digestion of seaweed, Sargassum tenerrimum, with a mixed bacterial culture consisting of methanogenic bacteria and an algin-degrading bacterial strain was carried out at different concentrations of dry total solids. Specific rate constants of biogas production during the lag, exponential and monomolecular (stationary) phases of bacterial growth were determined. About half the total volume of biogas was generated during the exponential phase irrespective of the concentration of seaweed in the digesters. The specific rates of substrate destruction and biogas generation in the stationary phase decreased with increasing substrate concentration. The yield of biogas per gram dry total solids of seaweed was about the same at all concentrations, but with a marked decline at 12% (w/v) total solids. The maximum destruction of volatile solids effected was about 63% over a period of 72 days.     

IC反应器水力特性实验研究

利用模拟实验的方法，从水力学的角度对压力、沼气产率以及温度与反应器内循环水流量的关系进行了实验研究。研究表明，压力变化是影响内循环水流量的最主要因素；反应器产气率对循环水流量的作用也非常显著，而且在一定范围内，反应器的循环水流量随产气率成线性关系变化；温度对反应器循环水流量的影响相对比较复杂，且与产气速率有很大关系；摩擦力对内循环水流量存在一定程度的影响，在反应器设计过程中不能忽略该因素。     

利用沼气技术综合治理酒精厂废液

论述了年产万吨酒精厂用红薯干为主要生产原料,采用生物厌氧,兼氧消化,好氧,物化处理等技术,综合治理酒精糟液的先进工艺,实现了日处理浓度有机污水400－500t,COD,BOD,SS降解净化率均在99％以上,出水达到GB8978－1996规定的第二类污染物二级排放标准。全年生产沼气255万－270万m^3,可获直接经济效益260余万元人民币。     

沼气发动机快速燃烧系统试验研究

从分析沼气燃烧特点出发,提出改善火花点火式沼气发动机性能的快速燃烧方法,并开发出具有风扇形燃烧室的新型快速燃烧系统。该燃烧系统在快速压缩膨胀装置上进行模拟,并在2135沼气发动机上进行实机试验,结果表明：风扇形燃烧室对加快混合气燃烧速度,改善沼气发动机中的燃烧过程有明显的效果;新型燃烧系统对改善火花点火式沼气发动机可靠性与经济性具有明显的效果。     

杭州湾地区浅层生物气资源量计算及其地质意义

杭州湾地区晚第四纪气源岩主要为河漫滩相和浅海相。经计算,河漫滩相源岩总生气量为1 032.52×10⁸m³,总吸附气量为274.66×10⁸m³,总溶解气量为693.10×10⁸m³,总扩散气量为4.29×10⁸m³,总游离气量为60.47×10⁸m³;而浅海相源岩相应为1 412.75×10⁸,556.68×10⁸,749.83×10⁸,10.28×10⁸和95.96×10⁸m³。这一计算结果显示了研究区浅层形成的生物气体首先受地层水的溶解和粘土的吸附,大部分溶解在粘土层水中呈水溶气相态发生运移,当甲烷气在地层水中溶解达到饱和后才会出现游离态。游离气主要赋存于沉积物颗粒间隙中,浅地层的游离气运移量远小于溶解气运移量,河漫滩相游离气量小于浅海相游离气量。浅海相沉积物总吸附气量为河漫滩相沉积物总吸附气量的2倍多,泥岩层的吸附气量是砂岩层吸附气量的18倍多,说明浅层沉积物颗粒大小与甲烷的保存有关,沉积物颗粒小、比表面积大有利于吸附甲烷。计算结果还表明,杭州湾地区浅层天然气具有广泛的勘探开发前景。     

Ultrasonic Sludge Pretreatment for Enhanced Sludge Digestion

During recent decades, the anaerobic digestion process has been extensively studied and various methods for process enhancement have been explored. These methods include heat treatment, alkali addition, phase separation and membrane enhancement. In general, whilst technically feasible, the methods have not proved to be economically competitive.
The pretreatment of sludges with high-power ultrasound has been investigated as part of a twelve-month research project funded by six UK water utilities. Cell lysis and particle-size reduction (caused by ultrasonic cavitation) are thought to be the key parameters through which the digestion process is enhanced. A series of laboratory-scale anaerobic digesters has been operated and significant increases in biogas yield have been noted following ultrasonication. Experiments have been completed with a variety of ultrasonic devices (of different geometries and construction materials) and sludge types (e.g. primary, secondary and co-settled). Current experiments are investigating methods through which the technology can be successfully scaled-up and applied on a full-scale plant.     

Characterization of Methane Emissions from Rice Fields in Asia. III. Mitigation Options and Future Research Needs

Methane (CH₄) emissions from rice fields were determined using automated measurement systems in China, India, Indonesia, Thailand, and the Philippines. Mitigation options were assessed separately for different baseline practices of irrigated rice, rainfed, and deepwater rice. Irrigated rice is the largest source of CH₄ and also offers the most options to modify crop management for reducing these emissions. Optimizing irrigation patterns by additional drainage periods in the field or an early timing of midseason drainage accounted for 7–80% of CH₄ emissions of the respective baseline practice. In baseline practices with high organic amendments, use of compost (58–63%), biogas residues (10–16%), and direct wet seeding (16–22%) should be considered mitigation options. In baseline practices using prilled urea as sole N source, use of ammonium sulfate could reduce CH₄ emission by 10–67%. In all rice ecosystems, CH₄ emissions can be reduced by fallow incorporation (11%) and mulching (11%) of rice straw as well as addition of phosphogypsum (9–73%). However, in rainfed and deepwater rice, mitigation options are very limited in both number and potential gains. The assessment of these crop management options includes their total factor productivity and possible adverse effects. Due to higher nitrous oxide (N₂O) emissions, changes in water regime are only recommended for rice systems with high baseline emissions of CH₄. Key objectives of future research are identifying and characterizing high-emitting rice systems, developing site-specific technology packages, ascertaining synergies with productivity, and accounting for N₂O emissions.