Charge transfer in plasma assisted dry reforming of methane using a nanosecond pulsed packed-bed reactor discharge

This paper is aimed to investigate the effect of packing material on plasma characteristic from the viewpoint of charge transfer process.Both the charge accumulation and release processes in the dielectric barrier discharge reactor and packed-bed reactor were investigated by measuring voltage and current waveforms and taking ICCD images.The packing material was ZrO2 pellets and the reactors were driven by a parameterized nanosecond pulse source.The quantity of transferred charges in the dielectric barrier discharge reactor was enhanced when decreasing pulse rise time or increasing pulse width(within 150 ns),but reduced when the gas gap was packed with pellets.The quantity of accumulated charges in the primary discharge was larger than the quantity of released charges in the secondary discharges in the dielectric barrier discharge reactor,but they were almost equal in the packed-bed reactor.It indicates that the discharge behavior has been changed from the view of charge transfer process once the gas gap was packed with pellets,and the ICCD images confirmed it.

Reaction Selectivity Improvement for Reduction of Nitrobenzene in a Packed-Bed Electrode Reactor under Periodic-Current Control

Rectangular wave current control of the electrochemical reduction of nitrobenzene im-proves the selectivity for p-aminophenol(PAP) compared to direct current(d.c.) control at thesame average current density in a flow-by packed-bed reactor.Optimal increase in PAP selectivitycan be obtained at about a frequency of 50Hz and a duty cycle of 0.2.A mathematical model isset up to incorporate the effects of mass transfer,hydrogen evolution and double layer charging,and is solved using the Duhamel’s superposition principle and the modified Crank-Nicolson methodwith the upwind scheme.The conventional d.c.control cases are also calculated for comparison.Calculations can be applied to predict the reaction results under periodic current and d.c.control,but both display the same trends compared to experimental data.

Numerical Modeling of NO Formation during Packed-bed Combustion of Coke Granules

A comprehensive kinetic model of NO formation during coke combustion in packed-bed in presence of noncombustible particles was developed. The detailed homogeneous gas-phase chemistry (including 102 chemical reactions), heterogeneous gas-solid chemistry (including 11 reactions) of coke combustion and NO formation, and the heat and mass transfer were taken into account in the present model. The governing equations which are strongly coupled, non-linear and unsteady with 26 unknowns in total, were dispersed into differential equations with the finite differential method. Meanwhile, all the differential equations were numerically solved to give the time-histories and space-distributions oftemperatures of the bed and gas phase as well as the concentrations of all the gaseous species. By comparison, the experimental data were explained well by the calculated results. Based on the kinetic and mathematical model, the effects of O2 content of inlet gas, the initial chemical analysis of coke, bed-temperature and local reductive atmosphere (CO/O2) on NO formation during packed-bed coke combustion were numerically discussed. It was found that coke samples with a higher initial content of [N] and volatile matters, combusted under a suitable O2-containing atmosphere produced less NO emission. The reactions between CO and NO, catalyzed by high temperature surface of coke particles may be responsible for efficient reduction of NO.

Ozone generation enhanced by silica catalyst in packed-bed DBD reactor

In this paper,three dielectric barrier discharge(DBD)configurations,which were plain DBD with no packing,DBD with packed pure quartz fibers and DBD with packed loaded quartz fibers,were employed to investigate the effect and catalytic mechanism of catalyst materials in a packed-bed ozone generator.From the experimental results,it was clear that the DBD configuration with packed pure fibers and packed loaded fibers promotes ozone generation.For the packed-bed reactor,ozone concentration and ozone yield were enhanced by an increase of electric field in the discharge gap with the packed-bed effect.Meanwhile,the enhancement of ozone concentration and yield for the DBD reactor packed by loaded fibers with silica nanoparticles was due to the catalysis of silica nanoparticles on the fiber surface.The adsorption of silica nanoparticles on the fiber surface can prolong the retention time of active species and enhance surface reactions.

Numerical simulation of packed-bed reactor for oxidative coupling of methane

A three-dimensional geometric model of the oxidative coupling of methane （OCM） packed-bed reactor loaded with Na2WO4-Mn/SiO2 partic- ulate catalyst was set up, and an improved Stansch kinetic model was established to calculate the OCM reactions using the computational fluid dynamics method and Fluent software. The simulation conditions were completely the same with the experimental conditions that the volume velocity of the reactant was 80 mL/min under standard state, the ratio of CH4/O2 was 3, the temperature and pressure were 800 ℃ and 1 atm, respectively. The contour of the characteristics parameters in the catalyst bed was analyzed, such as the species mass fractions, temperature, the heat flux on side wall surface, pressure, fluid density and velocity. The results showed that the calculated values matched well with the experimental values on the conversion of CH4 and the selectivity to products （C2H6, C2H4, CO2, CO） in the reactor outlet with an error range of 4-2%. The mass fractions of CH4 and O2 decreased from 0.6 and 0.4 in the catalyst bed inlet to 0.436 and 0.142 in the outlet, where the mass fractions of C2H6, C2H4, CO and CO2 were 0.035, 0.061, 0.032 and 0.106, respectively. Due to the existence of laminar boundary layer, the contours of each component bent upwards in the vicinity of the boundary layer. This OCM reaction was volume increase reaction and the total moles of products were greater than those of reactants. The flow field in the catalyst bed maintained constant temperature and pressure. The fluid density decreased gradually from 2.28 kg/m3 in the inlet of the catalyst bed to 2.22 kg/m3 in the outlet of the catalyst bed, while the velocity increased from 0.108 m/s to 0.115 m/s.

Effects of nitrogen on ozone synthesis in packed-bed dielectric barrier discharge

The effects of nitrogen on ozone synthesis are studied in a coaxial cylinder generator with dielectric barrier discharge（DBD） and pack-bed dielectric barrier discharge（PB-DBD）.A series of 10 h discharge experiments are conducted adopting a bare stainless electrode and bare copper electrode.Results show that the material of the electrode can affect the ozone synthesis.It is inferred that the ozone zero phenomenon（OZP） may be induced from ozone decomposing by metallic oxide catalysis.Packing dielectric particles can reduce the OZP.Adding a certain amount of nitrogen into the oxygen feed gas can further eliminate the OZP,and increase the ozone concentration significantly,but decreases the maximum energy efficiency of ozone generators.Initial analysis indicates that the optimal proportion of nitrogen addition is inversely related to the average reduced electric field strength in the discharge region.

Phytotoxicity Assessment of Biofertilizer Produced from Bioreactor Composting Technology Using Lettuce (Lactuca sativa L.) Seeds

Establishing reliable technological information on the safety of biofertilizers produced from a bioreactor composting technique is a must prior to its commercialization. A phytotoxicity study of biofertilizer made from the bioreactor composting technology at Aklan State University, Banga, Aklan, Philippines was conducted for fourteen (14) days using commercially available lettuce seeds (Lactuca sativa L.). Standard phytotoxicity attributes such as hypocotyl length, radicle length, relative germination percentage, and relative radicle growth observed during the germination stage were evaluated. Results revealed no significant difference in the radicle lengths of the germinated lettuce seeds as affected by the varying levels of biofertilizer dilution at H(3) = 10.567, p = 0.061 > 0.05. On the other hand, the hypocotyl length of the lettuce showed significant differences in response to varying levels of biofertilizer dilution with Welch’s F(5, 5.163) = 8.175, p = 0.017 < 0.05. Also, the different levels of biofertilizer affected significantly the germination percentage of lettuce seeds F(5, 12) = 5.822, p = 0.006 < 0.05. All levels of biofertilizer treatments indicated a decrease in relative germination percentage. However, those seeds applied with 10% biofertilizer have the highest reduction of germination percentage, equivalent to 86.9% (RGP = 13.10%). All levels of biofertilizer showed an increase in radicle growth in contrast to the negative control plant except for the one given a 10% level of biofertilizer. Seeds that received 10% biofertilizer showed an extremely high reduction in radicle growth, equivalent to 72.22% (RRG = 27.78%). The study shows that applying low levels of the bioreactor-produced biofertilizer will observably reduce the measure of the germination characteristics of lettuce seeds, but not necessarily low enough to be considered phytotoxic. However, the application of at least 10% bioreactor-produced biofertilizer can presumptively lead to phytotoxicity.

MBR与HMBR除污效能及相关功能微生物对比研究

复合式膜生物反应器(Hybrid membrane bioreactor,HMBR)是在膜生物反应器(Membrane bioreactor,MBR)中引入悬浮生物膜载体。利用高通量测序及相关分析软件筛选出具有降碳、脱氮、除磷功能的微生物,对比HMBR、MBR内微生物群落结构差异,结合两种反应器各自最优工况下对污染物去除效果,探究二者除污效能存在差异的原因。试验结果表明,HMBR的除污性能优于MBR,且MBR与HMBR污染物降解机制不同。HMBR拥有更优运行性能的原因在于HMBR内部拥有物种更加丰富、分布更加均匀、数量更多的微生物群落,相关功能菌在HMBR内增殖明显,尤其是悬浮填料的投加带来了功能菌的额外增量,从而提升了HMBR的污染物降碳、脱氮、除磷效能。

生物制氢原理及研究进展

主要综述了光解水、光发酵、暗发酵、暗-光发酵耦合等生物制氢技术,分析各方法的产氢机制、工艺优劣、影响因素和研究现状等,同时对比了生物制氢反应器的类型与特点。结果表明:生物制氢在低品位能源处理与高级能源生产方面具有巨大潜力。最后,给出了目前生物制氢技术的发展建议。

生物炭强化厌氧膜生物反应器处理废水性能的研究进展

厌氧膜生物反应器(AnMBR)因其在各种废水处理中对有机物的高效降解和能量的回收能力而受到研究者的广泛关注。生物炭具有优异的吸附和导电能力,将其添加在AnMBR中用于厌氧消化处理污废水,可以提高反应器性能并促进能源回收。基于此,系统综述了生物炭的制备和改性方法对生物炭性能影响的研究,以及近年来利用生物炭强化AnMBR处理性能的研究进展,并主要讨论了生物炭在AnMBR中的作用及主要机制,指出了目前生物炭强化AnMBR研究存在的问题和未来的发展方向,为生物炭强化AnMBR处理废水提供理论依据与技术参考。

不同进水方式对污泥床膨胀的影响

为了探究不同进水方式对污泥膨胀床性能的影响,设计一种侧向进水物理模型和四种不同进水夹角的底部进水口的数值模型,对比分析计算流体力学的三维模拟与实物模型的运行状态。结果表明:侧向进水方式污泥床在进水时膨胀速率比底部进水方式快19%;进水流量对两种进水方式的污泥膨胀高度及死区面积的减少有显著影响,在模拟中倾角为15°时,流量提升2.7倍,死区面积减少87%;底部圆锥倾角的变化,对死区产生显著的影响;侧向进水时,流场分为左右两部分,未有明显的优先流,底部进水则存在沿中轴线前进的主流,两侧的速度场分布梯度较小。

膜生物反应器在医疗废水处理中的应用

医院作为社会公共卫生体系的重要组成部分,其日常运营中产生的污水问题日益凸显。医疗废水作为一类特殊类型的废水,不仅含有高浓度的有机物、悬浮物,还携带大量的病原体,如细菌、病毒、寄生虫卵等,对环境和公众健康构成潜在威胁,所以必须确保医疗废水得到有效处理。在医疗废水处理领域,膜生物反应器凭借其卓越的处理效果、占地面积小、操作简便等优点,逐渐受到广泛关注。通过深入研究膜生物反应器在医疗废水处理中的工艺优化、运行参数调控、膜污染控制等关键问题,可以进一步提升其处理效率和稳定性,为医疗废水的高效、安全处理提供有力支持。基于此,分析膜生物反应器在医疗废水处理中的应用。

典型陶瓷膜在水处理中应用与研究进展

针对陶瓷膜技术在水处理中的应用,介绍了陶瓷膜发展历程和研究现状。综述了典型陶瓷膜在饮用水、海水淡化、生活污水和工业废水等方面的应用,以及近年来陶瓷膜分离与臭氧、光催化、微生物耦合技术及其应用于水处理领域的国内外研究进展。对陶瓷膜在水处理领域中的发展前景进行了展望。

200 m^(3)透明质酸生物反应器的流场模拟

随着透明质酸市场规模不断扩大,发酵生产透明质酸产量日益增多,为了对大型透明质酸生物反应器的放大设计提供理论依据,该文将透明质酸发酵液视为非牛顿流体,使用剪切应力输运模型对200 m^(3)生物反应器中不同搅拌器组合下的流场进行模拟建模。计算结果表明,使用斜叶桨式搅拌器流速最低,功耗最低,三折叶桨式搅拌器流速最高,流体流动性增强效果最好,功耗最高;弧叶圆盘涡轮搅拌器流体流速分布好于直叶圆盘涡轮搅拌器,功耗更低,更适合作为发酵罐底桨。综合流场分布,表观黏度分布以及轴功率数据考虑,选定最佳桨叶组合为三层三折叶桨式搅拌器+弧叶圆盘涡轮搅拌器进行发酵试生产,经过24 h发酵,透明质酸产率达到12.53 g/L。为工业高黏物料生物反应器放大设计提供了思路。

智能生物反应器装备制造进展

生物反应器是生物医药和生物技术产业的核心装备,全球生物反应器市场规模逐年增长,将成为装备制造领域重要的增长点。随着合成生物学和人工智能技术的迅猛发展,高通量、微型化生物反应器已开始应用于工艺开发和优化,大型生物反应器则朝着低能耗、智能化方向发展。生物反应器流场结构的复杂性是导致生物过程放大困难的关键问题之一,需要对反应器内的混合、传质、剪切等要素进行综合研究。为了提高生物反应器效率,需要采用人工智能和机器学习等技术进行数据采集和优化。未来结合生物技术、信息技术和控制技术的高集成度智能生物反应器将在多个领域有更广阔的发展空间。

合成生物学表型测试生物反应器及其装备化研究进展

合成生物学经过多年的发展,形成了典型的细胞工厂创制“设计-构建-测试-学习”(design-build-testlearn,DBTL)循环,成为支撑面向加速生物制造发展的智慧生物育种的重要方法。其中,测试环节是对前期所设计与构建的生物体系进行表型测试,以提供大量数据用于后续的学习和迭代升级。测试阶段的通量主要依赖于细胞自身或其培养测试所使用的生物反应器及其装备,是整个DBTL流程的限速步骤。本文系统综述了合成生物学表型测试所开发的面向不同通量的生物反应器及装备,从单细胞检测和筛选及不同尺度生物反应器包括皮纳升级生物反应器、微升级生物反应器、毫升级生物反应器和升级生物反应器等,系统地介绍了各自的特点和应用场景。同时,指出了现有生物反应器及其装备的应用潜力、面临的挑战与发展趋势,为合成生物学表型测试技术研究提供重要参考。

不同生物反应堆对设施黄瓜根际土壤细菌群落结构多样性的影响

研究不同生物反应堆处理对设施黄瓜根际土壤细菌群落结构及多样性的影响,旨在为黄瓜根际土壤改良和设施土壤可持续利用提供理论依据和现实基础。以16S rRNA基因V3-V4区为基础,设置原始温室土壤(CK),未经处理的黄瓜根际土壤100(CK1),200 d(CK2),玉米秸秆生物反应堆处理100(S1),200 d(S2)的根际土壤,羊粪生物反应堆处理100(M1),200 d(M2)的根际土壤7个处理,使用Illumina Miseq高通量测序技术对不同生物反应堆处理下的设施黄瓜进行根际土壤细菌群落多样性、结构、理化性质分析。结果表明,土壤样品经测序后共得到6344个OTUs,主要隶属于39门315目980属;M2处理可提高黄瓜根际土壤细菌丰富度,并显著增加细菌群落多样性。在门水平上,玉米秸秆生物反应堆处理和羊粪生物反应堆处理土壤细菌门水平优势种群结构相似,其中放线菌门和变形菌门是优势菌门;在属水平上,norank_f_JG30-KF-CM、节杆菌属、norank_f_norank_o_Gaiellales、norank_f_67-14、芽球菌属、Gaiella、火山岩海球菌属(Marmoricola)在不同处理之间有显著差异;从细菌群落丰度组成情况来看,M2处理和S2处理在一定程度上提高了黄瓜根际部分有益细菌类群相对丰度;RDA分析表明,土壤细菌群落受土壤环境因子的影响显著,铵态氮含量(P=0.015)、全钾含量(P=0.002)、速效钾含量(P=0.005)对细菌群落影响显著。因此,M2处理可提高设施黄瓜根际土壤细菌丰富度、增加细菌群落多样性、改变细菌群落结构,有利于设施黄瓜根际土壤的改良。

MBR处理农村生活污水及膜污染控制研究进展

农村生活污水水质水量变化大,排放量小但分布分散,污染物浓度较高。而膜生物反应器(MBR)抗冲击负荷能力强、占地面积小、污染物去除效率高。因此,MBR技术在农村生活污水处理市场的前景较为广阔。这里主要从农村生活污水的特点及处理技术、国内外利用MBR处理农村生活污水的现状、膜污染的作用机制和类型以及控制措施三个方面进行了综述。通过国内外应用现状对比,发现分质处理能更好地实现资源回收,并减轻MBR在脱氮除磷方面的压力;针对膜污染问题,建议从改性膜材料、改良污泥混合液特性、改善操作条件和膜清洗入手,以此来减缓膜污染,降低运行成本,从而更好地推进该技术在农村地区的应用。

利用甲烷氧化菌产生聚-β-羟基丁酸酯的研究进展

聚-β-羟基丁酸酯(PHB)是原核微生物产生的一种生物聚酯,主要作为储能物质以颗粒形式在细胞内积累,具有良好的生物相容性、生物降解性、非线性光学活性、成膜性、气体相隔性、抗凝血性等高附加值性能,被认为是化石聚合物的可再生与可生物降解替代品,对缓解世界化石能源危机与环境污染有积极作用。系统总结了目前可生产PHB的甲烷氧化菌种、PHB在菌体内的合成途径、影响甲烷氧化菌累积PHB的因素,并对存在的问题和未来的发展趋势进行了探讨。

半疏水晶胶微球的悬浮特性及固载乳杆菌合成有机酸

针对有机酸生物合成过程中底物和产物抑制、细胞密度低和耐受性弱等问题,采用“结晶致孔-低温聚合”方法制备聚甲基丙烯酸羟乙酯-甲基丙烯酸丁酯半疏水晶胶微球,通过高速成像和数值模拟研究10 L搅拌式生物反应器(STR)内的悬浮行为,通过固载乳杆菌分析半疏水晶胶微球在乳酸和苯乳酸生物合成中的作用。结果表明,数值模拟得到晶胶微球的悬浮特性与高速成像实验结果基本一致,体积分数为3%的晶胶微球均匀悬浮所需最低搅拌转速为55 r·min-1;在晶胶固载乳杆菌发酵联产乳酸和苯乳酸过程中,乳杆菌生物量达10.5 g·L^(-1),相比于无载体发酵提高了84.2%;在第1次补料期间,乳酸的发酵周期大幅缩短至21 h,比无载体发酵周期缩短了50%。