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关键词： 膜生物反应器   船舶生活污水   脱氮除碳   膜污染  

摘要： 随着海洋环境污染加重,世界各国对海洋环境越来越重视,污水排放指标不断提升,加之恶劣的船舶环境对船舶污水处理是一大挑战。与其他船舶污水处理设备相比较,船用膜生物反应器（MBR）具备去除稳定、抗冲击摇摆能力强、体积小等优点,备受大家关注。然而船用MBR仍可以进一步优化:提升效能、减轻膜污染。因此本文对一种外置式MBR反应器及对其优化后得到的改进型MBR反应器进行研究,探究常规因子对其脱氮除碳效能的影响,并通过优化前后的对比,分析优化后反应器的优劣势。对于外置式MBR反应器,提升进水容积负荷有利于化学需氧量（COD）的去除,当负荷达到1.6 kg/m·d时,COD去除率达到94.98%,但过低的负荷会影响生物生长,进而影响COD的去除率,碳源是否充足对其总氮（TN）的去除效能是至关重要的,进水碳氮比（C/N）为12:1时,TN去除率达到83.38%,膜组件对TN和COD几乎没有去除效能。改进型MBR反应器是对对外置式反应器结构和运行方式上优化后得到的,结构上将外置式反应器的单一生化区分成了好氧区和厌氧区结合的形式,运行方式上将膜组件与厌氧区结合,形成了独特的运行环境。对于改进型MBR反应器,在0.8～1.6 kg/m·d进水容积负荷下,反应器对COD去除效能一直保持在92%4%的高水平,对TN的去除效能较为稳定,受进水容积负荷影响较小,一直保持在88.8%1.7%的高水平,尤其在低负荷下,依然能有较高的去除效能,反应器TN去除率随进水C/N的减小先增大后减小,且在进水C/N=12:1时得到最佳TN去除率87.1%。优化后的优势在于对抗进水COD冲击的调整能力增强,对COD和TN的去除效能明显提高,在低进水容积负荷去除效能更好,且受进水容积负荷影响更小,效能更稳定,改进型MBR反应器膜组件污染情况虽然稍重,但尚在可接受范围内,且提高了膜组件对系统的处理保障和效能。总体上改进型MBR反应器的脱氮除碳效能优于外置式MBR反应器。

关键词： Syngas fermentation   bioethanol   mass transfer   Clostridium ljungdahlii  

摘要： Ontario biomass could be thermochemically processed by dry and wet torrefaction to produce high quality solid biofuel. These solid fuels or raw biomass could also be gasified to produce syngas. This study analyzes and demonstrates a successful and efficient way of producing bioethanol from syngas fermentation using Clostridium ljungdahlii in a laboratory scale continuous stirred tank bioreactor having an innovative gas supply and effluent extraction structures. At the beginning of the experiment, a batch process was conducted to grow microorganisms and allow the growth of the microorganisms to reach to maximum cell density in a reactor without supplying a gas. Ethanol production was observed by supplying two different gas compositions which included 100% CO and simulated syngas, mimicking the composition of syngas extracted from lignocellulosic biomass having 60% CO, 35% H-2, and 5% CO2. CO and syngas were fermented with different gas flow (5-15 mL/min), effluent flow (0.25-0.75 mL/min), and media flow rates and stirrer speed (300-500 rpm) at atmospheric pressure and 37 degrees C. The gas flow rate, media and effluent flow rate, pH level, and stirrer speed were controlled during the fermentation process. The exhaust gas was reused for the improvement of residence time using a loop-back system for improving the gas-liquid mass transfer. Excessive foam was observed during the fermentation process which was controlled using diluted antifoam-204. Maximum cell concentration reached 2.4 g/L. The mass transfer coefficient showed better performance during syngas fermentation than CO fermentation. More bioethanol production was observed by syngas fermentation than CO fermentation. CO fermentation produced 0.17-1.33 g/L-effluent ethanol and 8.92-23.67 g/L-effluent acetic acid whereas syngas fermentation produced 0.85-3.75 g/L-effluent ethanol and 8.89-14.97 g/L-effluent acetic acid.

关键词： 膜生物反应器   污水处理   膜过滤  

摘要： 膜生物反应器是将膜分离技术与活性污泥法相结合的高效污水处理技术.本文综述了膜生物反应器的发展历程、典型应用案例现状及存在的问题、MBR工艺今后在污水处理中应用前景,为MBR工艺今后的进一步研究和应用提供参考.

关键词： 烟酸   腈水解酶   反应优化   细胞固定化   生物反应器  

摘要： 烟酸作为维生素类药物,是人体中不可或缺的营养成分。生物催化绿色、经济地合成烟酸技术的开发具有重要研究意义。本论文以来源于敏捷嗜酸菌72W中的大肠杆菌重组腈水解酶为催化剂,对3-氰基吡啶水解生成烟酸的过程进行研究。构建了能够双位点表达腈水解酶的重组菌*** pRSF-NIT2。通过对培养条件、反应体系优化和细胞固定化研究,获得高活性、高稳定性固定化细胞,最终在生物反应器中实现烟酸的高效生物合成。本文主要研究内容包括:首先,构建重组菌*** pRSF-NIT2。在已有*** p ET21a-NIT的基础上,通过PCR技术、酶切连接实验将腈水解酶基因连接到质粒pRSFDuet质粒双克隆表达位点上,并导入到大肠杆菌BL21（DE3）宿主菌中,成功构建了双位点表达腈水解酶的工程菌*** pRSF-NIT2。研究发现*** pRSF-NIT2无需添加诱导剂即可实现腈水解酶的表达。在此基础上对此工程菌的发酵产酶培养基和产酶条件进行了系统优化,研究发现*** pRSF-NIT2无需添加诱导剂即可实现腈水解酶的表达,最佳发酵培养基组分为（g/L）:可溶性淀粉20;酵母粉15;氯化钠5;K2HPO44;Mg SO4·H2O 1;最优产酶条件及结果为:在30℃,200 rpm下摇床培养16 h,最终细胞量和酶活分别可达到4.0 gdcw/L和2846U/L。在摇床水平的基础上,将重组菌在5 L发酵罐中进行放大培养,最终在30℃,300rpm条件下培养12 h,细胞量和酶活分别为5.38 gdcw/L和3058 U/L。其次,对重组菌整细胞催化3-氰基吡啶水解进行了考察,对反应的一系列条件进行了优化。最适反应pH为7.0,最适温度为30℃。当进行单一浓度优化时,底物浓度在100-800 m M时,反应在4h内都能完全转化,当底物浓度为1 M时,需要6 h完全转化;底物浓度继续提高到1.6 M后,8 h后反应转化率仅有20%左右。初始底物浓度为1 M,分批补料浓度为200 m M时,可以连续补料10次,仍可以达100%的转化率,最终产物浓度为3 M。最后,考察几种不同的固定化细胞方法,发现海藻酸钠/戊二醛/聚乙烯亚胺固定化的方法最佳。对固定化的条件以及固定化细胞的性能进行了考察。最终确定了最佳条件为:大肠杆菌浓度15 g/L,海藻酸钠浓度2%,戊二醛浓度2%,PEI浓度为3%。对固定化细胞的催化性质进行研究,其最适温度和pH分别为30℃,Tris-HCl 8.0,固定化细胞的热稳定性和pH稳定性都有所提高,固定化细胞在保存60天以后剩余酶活仍有82%而游离细胞只有15%。利用固定化细胞作为生物催化剂,在填充床反应器中进行半连续催化反应,并对反应器中底物流速、底物浓度以及重复使用性进行研究,研究结果为:底物浓度为0.8 M、底物溶液流速为2 m L/min时可获得最高的时空产率1576 g/L/d,反应器重复使用41批次转化率保持100%,生产1吨烟酸约需6 kg干重的细胞。

关键词： 膜生物反应器   污水处理   处理技术  

摘要： 目前,'膜生物反应器'作为一种污水处理技术,在诸多领域都有其应用发挥.本文通过对膜生物反应器在城市、工业污水处理中的实际应用进行分析,主要采用理论概述、作作用分析等方式,基于城市、工业污水排放对环境污染的重要性,为膜生物反应器技术进一步推广应用提供依据参考.

关键词： bioreactor   computational fluid dynamics   tissue engineering  

摘要： The objective of this study was to model monocyte migration and differentiation into dendritic cells under a variety of conditions in a novel designed plate bioreactor with flow using Computational Fluid Dynamics (CFD) simulation software. The model was developed to study fluid flow phenomena throughout the geometry such as shear rate patterns and velocity streamlines that can be expected over a range of parameters. Additionally, monocyte and dendritic cell concentrations were predicted for the same conditions to provide insight for actual experimental conditions and make recommendations for an optimal setup. To model the endothelial cell layer that was cultured in the plate bioreactor during experiments, this region of the bioreactor was set up in the model as a porous media with viscous and inertial resistance calculated based on cell properties and porosity of the layer. Using preliminary experimental data for the plate bioreactor, a monocyte death rate correlation was developed as a function of local shear rate and a first-order kinetics reaction correlation was developed to describe the differentiation of monocytes into dendritic cells. These correlations were incorporated into the developed model in the form of User-Defined Functions (UDFs) so that cell concentrations could be monitored over the duration of actual experimental time. The plate bioreactor was simulated for 48 hours at an inlet Reynolds number (Rein) ranging from 2.5 to 25 and inlet monocyte concentration ranging from 250,000 cells/mL to 1,000,000 cells/mL. Concentrations of both monocytes and dendritic cells were greatly affected by the changing of Rein. Results showed that a Rein of 5.0 provides the most optimal conditions in an experimental setting. As Rein increases beyond 5.0, it is predicted that the number of still living monocytes and differentiated dendritic cells will greatly decrease in a 48-hour experiment. Simulation results were validated by measuring monocyte and dendritic cell con

关键词： 废水   膜生物   反应器技术  

摘要： 生态环保理念深入人心,多年来我国政府致力于建设环境友好型社会,'绿色生态'发展与生产精髓融入到了我国各行各业的发展中,也是促进可持续发展的必然趋势.基于此,本文将结合膜生物反应技术的工艺组成种类,不断强化绿色发展建设,探寻它在水与废水处理中的实际应用方法.

关键词： 固定化微生物反应器   含铜废水   扫描电镜   气单胞菌  

摘要： 电镀、矿山开采等行业产生大量的含铜废水,其中的Cu短时间内难以降解,对环境和人体健康造成影响。固定化微生物技术处理效率高、成本低廉,因此,本文对固定化气单胞菌小球组建的固定化微生物反应器处理含铜废水进行模拟研究。以聚乙烯醇3%、海藻酸钠1.8%、明胶0.5%为制备条件,得出此条件下固定化气单胞菌小球对Cu的吸附率为62.59%。通过扫描电镜分析,发现小球表面的褶皱以及内部的网状空隙都有利于微生物的生长,为固定化小球去除Cu提供必要基础。通过模拟组建固定化微生物反应器,以处理时间、Cu初始浓度、气单胞菌用量、营养物质浓度、曝气时间为单因素控制变量,进行固定化微生物反应器处理含铜废水的实验研究。结果表明反应器最佳吸附时间为6h、Cu初始浓度120mg/L、气单胞菌20g/L、营养物质浓度80g/L、曝气时间为1h,可实现对Cu的最优处理效果。吸附动力学分析表明,Cu与固定化微生物反应器中的固定化气单胞菌小球接触,进而与褶皱充分接触,通过表面孔隙进入小球内部,通过小扩散作用,与气单胞菌进行充分的接触,降低废水中Cu含量。固定化微生物反应器吸附是多层吸附。同时,随着反应器中固定化气单胞菌小球的增加,反应器处理含铜废水的效果会更好。经过对Cu的吸附-解吸迟滞性进行分析,Cu具有一定的解吸迟滞性,但是其影响较小,表明反应器中的固定化气单胞菌小球具有较好的再生性和重复利用性。扫描电镜结果表明,吸附后的固定化气单胞菌小球上存在着大量完整的气单胞菌附着在小球内部,说明气单胞菌在固定化材料内透过表面孔隙,可以从生存环境中获取营养物质生长繁殖,保持生命活性,证明气单胞菌具有良好的再生性,用固定化气单胞菌作为微生物反应器的生物填料,可实现连续性处理废水的目的。通过对比处理前后固定化气单胞菌的傅里叶红外光谱图,分析得出主要是-OH键、B-O键、C-H键、-CH-键参与到固定化气单胞菌处理含铜废水的过程中。

关键词： Free ammonia inhibition   granule size   AOB:NOB ratio   partial nitritation-anammox  

摘要： A partial nitritation-anammox continuous flow reactor (CFR) was operated for eight months demonstrating that a mixture of large anammox-supported aerobic granules (ASAGs) and small conventional aerobic granules (CAGs) can be maintained stably for extended periods of time. The influent NH4+ was kept at 50 - 60 mg N L-1 to verify that the upper range of total ammonia nitrogen (TAN) for domestic wastewater can supply an inhibitory level of free ammonia (FA) for nitrite oxidizing bacteria (NOB) suppression in CFRs at pH around 7.8. The ammonia oxidizing bacteria (AOB):NOB activity ratio was determined for a series of granule sizes to understand the impact of mass diffusion limitation on the FA inhibition of NOB. When dissolved oxygen (DO) limitation is the only mechanism for NOB suppression, the AOB:NOB ratio was usually found in previous studies to increase with the granule size. However, the trend is reversed when FA has an inhibitory effect on NOB, as was observed in this study. The decrease in AOB:NOB ratio indicates that the resistance to the diffusion of FA along the granule radius limited its ability to inhibit NOB. This means smaller granules, e.g. diameter < 150 microns, are preferred for nitrite accumulation when high FA is present, e.g. in the partial nitritation-anammox process. The trend was further verified by observing the increase in the apparent inhibition coefficient, KI,FAapp, as granule size increased. This study for the first time quantified the effect of diffusion limitation on the KI,FAapp of NOB in granules and biofilms. A mathematical model was then utilized to interpret the observed suppression of NOB. The model predicted that NOB suppression was only complete at the granule surface. The NOB that did survive in larger granules was forced to dwell within the granule interior, where the FA concentration was lower than that in the bulk solution. This means FA inhibition can be taken advantage of as an effective means for NOB suppression in small g

关键词： 苯酚分离与降解   萃取式膜生物反应器   选择性渗透萃取膜   静电纺丝   聚二甲基硅氧烷  

摘要： 近年来,水环境中以苯酚高盐废水为代表的难降解有机高盐废水排放量日益增加。苯酚是重要的工业原材料,也是世界卫生组织认定的3类致癌物,对水生动植物、人类的健康危害显著。高盐条件下,苯酚处理常用的物理-化学法、膜分离法、生物处理法等普遍面临分离精度低、降解难度大、二次污染加剧等风险。集渗透萃取膜和污染物降解菌为一体的萃取式膜生物反应器（extractive membrane bioreactor,EMBR）是处理苯酚高盐废水的有效途径。EMBR中选择性渗透萃取膜将废水和微生物完全隔开:在浓度差驱动下,废水中的苯酚可通过溶解-扩散机理透过膜,被微生物降解;而盐离子不能透过膜,不会影响微生物代谢活性,从而实现高盐废水中苯酚的高效分离、回收与降解。然而传统内置式EMBR（采用硅橡胶管式膜）受膜材料传质阻力大、传质系数低、生物膜过度附着等限制,其研究、应用、推广并不顺利。针对上述问题,该研究以硅橡胶管式膜的主要成分聚二甲基硅氧烷（polydimethylsiloxane,PDMS）为功能性高分子材料,经高压静电纺丝制备新型高通量选择性渗透萃取膜,提高苯酚的跨膜传质系数;构建新型外置式EMBR,隔绝微生物与膜的接触,从根本上解决膜污染问题。具体的研究结论如下:1)使用硅橡胶管式膜和普通活性污泥组建的传统内置式EMBR可处理苯酚高盐废水。探究了不同废水循环流量对苯酚渗透萃取和盐离子截留的影响,研究结果表明废水循环流量为1.8 L h-1、微生物单元HRT为48小时,最适合苯酚高盐废水的分离与降解。随苯酚高盐废水(氯化钠浓度35.0 g L-1)中苯酚浓度的提高(1.0至5.0g L-1),渗透萃取过膜的苯酚浓度逐渐从55.6提高至273.9 mg L-1,同时氯化钠截留率高于99.97%。研究表明在最优条件下,硅橡胶管式膜的苯酚平均跨膜传质系数为1.29×10-7 m s-1,该内置式EMBR的最大苯酚降解容量为136.9 mg L-1 d-1。2)采用高压静电纺丝技术,以PDMS为功能性高分子材料、聚甲基丙烯酸甲酯（polymethyl methacrylate,PMMA）为基质性高分子材料,以四氢呋喃（tetrahydrofuran,THF）和二甲基甲酰胺（dimethyl formamide,DMF）为复合溶剂,成功制备了静电纺丝PDMS/PMMA渗透萃取多孔膜。探究了PMMA浓度、PDMS/PMMA质量比、粘度、电压、推注流量、针头内径等一系列聚合物、纺丝液、过程参数对膜制备、膜形貌、膜纤维直径、膜孔径、膜表面粗糙度、膜表面浸润性的影响,研究结果表明膜表面粗糙度与表面水接触角呈正相关关系（R2为0.790-0.794）。该研究确定了超疏水亲有机的静电纺丝PDMS/PMMA渗透萃取多孔膜的最优制备条件为PDMS/PDMS交联剂/PMMA/THF/DMF质量比10/1/10/50/50,针头内径0.6 mm,正电压10.5 kV,负电压1.0 kV,针尖到接收器距离16 cm,推注流量1.0 mL h-1,纺丝时间500 min,温度25~oC,湿度35%。所制备的膜表面水接触角162.0~o,苯酚接触角0~o,膜纤维直径1.28μm,膜孔径4.74μm,膜厚度78.7μm,膜表面粗糙度5.8μm。3)以超疏水亲有机的静电纺丝PDMS/PMMA渗透萃取多孔膜为膜材料构建无微生物的EMBR（即膜芳香烃回收系统,membrane aromatic recovery system,MARS）,实现了苯酚高盐废水的原位分离。探究了不同水力条件、温度、pH对苯酚渗透萃取和盐离子截留的影响,发现废水流量0.90 L h-1、接收液流量1.26 L h-1是苯酚分离的最优水力条件,较高废水温度（40~oC）和较低废水pH（2.5）也有助于提高苯酚的分离回收率。当废水中苯酚从2.0提高至10.0 g L-1时,苯酚的渗透萃取浓度逐步从427.4提高至2386.4 mg L-1,24小时后回收率稳定在21.2-23.9%;而当氯化钠浓度逐步从10.0提高至50.0 g L-1时,盐离子截留率稳定在99.96%以上,未受影响。在不使用NaOH、HCl等萃取剂的情况下,静电纺丝PDMS/PMMA膜的苯酚平均跨膜传质系数为6.7×10-7 m s-1。膜吸附-膜内扩散-膜脱附的分离机理,规避了传统膜分离中膜孔堵塞等问题,3个周期内,膜形貌、膜表面官能团、膜分离效果均保持稳定。4)以超疏水亲有机的静电纺丝PDMS/PMMA渗透萃取多孔膜为膜材料,以驯化后的活性污泥为微生物,构建新型外置式EMBR,实现了苯酚高盐废水的原位分离与降解。外置式膜构型将膜与微生物隔离,生物膜过度生长问题不复存在。探究了外置式EMBR的最优水力条件,研究结果表明当废水、营养液流量均为0.18