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关键词： Liquid-solid fluidised bed   Bed expansion   Terminal velocity   Tissue engineering  

摘要： Fluidised bed bioreactors (FBBs) are a promising alternative to provide high cell densities and a more defined culture environment for 2D and 3D cell cultures. However, for their wider use in biotechnology applications, a better understanding of their hydrodynamics is required. In this work, the fluidisation properties of three common particles in tissue engineering - single cells, cells clusters, and gel microbeads - were evaluated and compared to established liquid fluidisation correlations. Only a few studies to date have attempted to characterise the hydrodynamic behaviour of gel beads, while none were found for the other two particle types studied here. All particles were in the micrometre size range and their densities were found to be near-equal to the fluid phase. The particle terminal velocities were measured and corrected for hindrance effects, but these values were poorly predicted by equations proposed for rigid smooth spheres. Bed expansion data was presented in the form of logarithmic plots of velocity against voidage and analysed in terms of Richardson & Zaki parameters (n, expansion index and k, correction factor). Linear relationships were observed in these graphs;however, the fitting parameters were incorrectly predicted by the established equations. Therefore, modified Richardson-Zaki correlations were developed by using experimental parameters for n and k, to enable other users to set up FBBs for tissue engineering applications.

关键词： Electro-assisted   AnOMEBR   Electrostatic repulsion   Membrane fouling alleviation   Membrane surface charge  

摘要： Anaerobic forward osmosis membrane bioreactor (AnOMBR) is a potential wastewater treatment technology, due to its low energy consumption and high effluent quality. However, membrane fouling is still a considerable problem which causes dwindling of water flux and shortening the membrane lifetime. In this study, electro-assisted anaerobic forward osmosis membrane bioreactor (AnOMEBR) was developed to treat wastewater and mitigate membrane fouling, in which the conductive FO membrane was used both as the separation unit and cathode. The formation, development and alleviation of membrane fouling in AnOMEBR were investigated. The results showed that the soluble microbial products (SMP) content and the proteins/polysaccharides (PN/PS) value in AnOMEBR were 26% and 15% lower than that in AnOMBR, respectively. The absolute value of Zeta of sludgemixture in AnOMEBR was 1.2 times that of the AnOMBR. The increase in the interaction between themembrane surface and the negatively charged foulants could inhibit the adsorption of foulants on membrane surface in the initial stage of membrane fouling. The strong interaction among foulants further affected the composition, structure and thickness of the cake layer on the FO membrane surface. AnOMEBR with a shorter hydraulic retention time, a higher organic loading rate and a lower osmotic pressure difference, could still obtain a lower flux decline rate of 0.063 LMH/h, which was 35.7% lower than AnOMBR. The wastewater treatment capacity of AnOMEBR was nearly 1.5 times that of the AnOMBR. This work provides an efficient strategy for mitigating membrane fouling and improving wastewater treatment capacity. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Hydraulic fracturing flowback   Membrane bioreactor   Membrane fouling   Fe nanomaterials   PAHs  

摘要： The rising water-use intensity, and lack of cost-effective treatment strategy and reuse of hydraulic fracturing flowback (HFF) has become an increasing cause of concern. The present work evaluates the integration of parallel sets of tandem anaerobic-oxic membrane bioreactor (AMBR) with and without nano-Fe for treatment and reuse of real HFF obtained from Ordos Basin, China. Treatment efficiencies in terms of organic conversions, micro-pollutants degradation, resource recovery, and effects of nano-Fe release on membrane fouling were evaluated. Nano-Fe mediated AMBR (FAMBR) system effectively reduce target micro-pollutants (such as Acenaphthylene) at 94.4 % compared to the parallel AMBR system (17.1 % without nano-Fe). Moreover, recovery of potential economic chemicals like Al and P (1.0 and 0.6 mg/g spent nano-Fe) availed using FAMBR system. However, colonization of FAMBR membrane surface by Fe-protein/peptide hydroxocomplexes initiated by Fe-catalyzed microbial extrusions present a huge fouling challenge relative to the AMBR system. Additional evidences from microscopic/spectroscopic analysis of the FAMBR membrane system revealed that despite having a promising outlook, mediation of nano-Fe with AMBR system might result in a major fouling event during HFF treatment. Engineered design of nano-Fe to reduced leached nano-Fe ions in pre-treatment step prior to AMBR treatment system may be of potential research consideration.

关键词： lipase   SiO2   electrospinning   membrane bioreactor   interface  

摘要： Lipase is one of the most widely used enzymes in biocatalysis. Because of the special structure of the catalytic active center, lipases show high catalytic activity at oil-water interfaces. Hence, the interface plays a key role in activating and modulating lipase biocatalysis. Compared with traditional catalytic systems that offer interfaces, such as emulsions, a lipase-membrane bioreactor exhibits many obvious advantages when at the macroscopic oil-water system. In our current research, a series of new Burkholderia cepacia lipase (BCL)-SiO2 nanofiber membrane (NFM) bioreactors prepared via combined electrospinning and immobilization strategies were reported. These SiO2 NFMs assisted BCL in reaching the oil-water interface for efficient catalysis. The enzyme loading capacity and catalytic efficiency of BCL-SiO2 NFMs varied with the surface hydrophobicity of the electrospun NFMs. As the hydrophobicity increased, the activity decreased from 2.43-fold to 0.74-fold that of free BCL. However, the lipaseloading capacity increased obviously when the hydrophobicity of the SiO2 NFMs increased from 0 to 143 degrees, and no significant change was observed when the hydrophobicity of the SiO2 NFMs increased from 143 to 153 degrees. The gel trapping technique proved that the hydrolytic activity of the different BCL-SiO2 NFM bioreactors depends on the contact area of the membrane at the oil-water interface. BCL-SiO2 NFM, BCL-SiO2 NFM-C12, and BCL-SiO2 NFM-C-18 retained 32, 83, and 42% of activity, respectively, after five cycles of reuse. The current work was a useful exploration of the construction and modification of lipase- membrane reactors based on electrospun inorganic silicon.

关键词： 硝化   反硝化   缺氧/好氧(A/O)法   回流   生物反应器  

摘要： 目前大多数城市污水处理工艺主要还是以活性污泥法为主.为了提高水处理时总氮(N)的去除效率,缺氧/好氧(A/O)工艺被普遍采用.但在该工艺中,缺氧池(A池)和好氧池(O池)通常均没有独立的沉降过程,因此两池之间的回流都是连泥带水一起回流.基于专利技术“垂直折流式生物反应器”(VBBR)可以轻易实现泥水分离,做到清水回流,因此研究采用对比的方法探讨了清水回流是否可以提高硝化和反硝化速率.实验结果表明:若采用清水回流,相比传统的泥水回流,其硝化速率可以提高12%,反硝化速率则可以提高2.5倍.该实验结果为今后城市污水处理过程中高效脱氮打下了良好的理论和实践基础.

关键词： 糖尿病   基质细胞衍生因子1   溃疡  

摘要： 目的探讨外源性基质细胞衍生因子1(SDF-1)治疗糖尿病大鼠皮肤溃疡愈合的最佳浓度。方法在糖尿病SD大鼠上制作皮肤溃疡模型,随机分为对照组(Con)、SDF-1干预高剂量(H)组、中剂量(M)组和低剂量(L)组,每组各6只。各组溃疡创面分别予0.9%生理盐水及50、25和12.5μg/kg的SDF-1干预。观察各组溃疡创面愈合情况、愈合率,检测成纤维细胞生长因子(FGF)、羟脯氨酸(HYP)、VEGF及SDF-1含量。结果M组成纤维细胞和毛细血管数量及形态均优于其他三组。与同时间点Con、L组比较,M组创面愈合率高(P<0.05)。M组FGF含量在第7、14、21天高于其他3组(P<0.05),HYP含量在第3、7、14、21天高于其他3组(P<0.05)。除第7天外,M组VEGF含量高于其他3组(P<0.05)。M组SDF-1含量高于Con组(P<0.05)。M组△FGF高于其他3组(P<0.05)。M组△HYP高于H组(P<0.05)。Con、M组△VEGF高于L组(P<0.05)。结论25μg/kg是SDF-1促进溃疡愈合的最佳浓度,可提高糖尿病皮肤溃疡的愈合率和质量。

关键词： 灰色链霉菌   链霉素   纤维床生物反应器   发酵  

摘要： 利用纤维床生物反应器(FBB)发酵生产链霉素,对发酵培养基氮源进行了优化,并与传统搅拌发酵进行了比较。结果表明,以可溶性有机氮源大豆蛋白胨作为发酵培养基氮源,并添加一定量蔗糖,可以完全替代黄豆粉,在1 LFBB中发酵96 h时链霉素效价达到5567 U·mL^-1。在整个发酵过程中,所有菌体都被固定在纤维床反应器上,而发酵液保持澄清,这不仅有利于从无菌体的发酵液中进行产物的提取和纯化,也可以重复利用菌体生产次级代谢产物,从而缩短发酵周期,进一步提高链霉素在发酵过程中的体积生产率。

关键词： Bubble column   Hydrodynamics   Hold-up   Three-phase system   In-situ product recovery  

摘要： There is increasing interest in the development of in situ product recovery technologies for bioprocesses as they have the potential to improve both process performance and economics. The most widely used technique is liquid-liquid extraction. However, relatively little hydrodynamic data about three-phase (gas-organic-aqueous) bubble columns are available. In this work we have examined the effect of three oil phases on the hold-up, bubble size distribution and droplet size distribution at oil loadings between 0.01 and 5% (v/v) and superficial velocities between 0.01 and 0.10 m/s. It was found that the oil phase was evenly dispersed throughout the column, addition of the oil led to a reduction in the overall hold-up by up to 34%. The recovery of three terpenoid compounds (limonene, nerolidol and β-carotene) was examined using 1% (v/v) hexadecane as the extraction phase. It was found that the organic phase could be separated using a simple gravity separator; product recoveries ranged from 66 to 95% for an air/water system. 5 g L⁻¹ molasses was added to mimic fermentation medium, this led to an approximately 10% reduction in the observed recovery. The approach used concentrates the product by a factor of approximately 100, is mechanically simple and can be readily adapted to continuous operation, which are advantages from a scale-up perspective. Results from this work can be used in the design and scale-up of in situ product recovery technologies for bubble column bioreactors.

关键词： 硝化细菌   富集培养   AOB   生物反应器   种群平衡   固定化  

摘要： 为探究出有效的硝化细菌规模化快速富集方法,使用工业级生物反应器完成了硝化细菌的快速富集培养。从数据结果和高通量结果确定24~27 d为最佳经济取泥期,污泥浓度3000~4000 mg·L^-1为最佳细菌增长控制浓度,稳定运行阶段单日产泥量为0.3 kg·(m^3·d)^-1。对比和分析活性污泥及整个培养过程中污泥群落在不同水平上的变化,发现较短时间即可实现功能菌筛选及产出。证明了该工业级生物反应器对硝化细菌规模化快速富集培养并稳定产泥方法的可行性。为包埋固定化技术实现规模化应用在菌源制备方面提供了技术路线。通过硝化细菌培养实验探究,优化了培养周期,解析了菌群演变规律。

关键词： 厌氧   生物质   生物反应器   黄贮玉米秸秆   发酵特性  

摘要： 为提高厌氧发酵的效率和秸秆利用率,将玉米干秸秆经过物理生物联合预处理形成黄贮玉米秸秆。本研究通过实验考察了黄贮玉米秸秆在竖向推流反应器(vertical plug flow,VPF)、全混流反应器(continuous stirred tank reactor,CSTR)和由本文作者课题组首创的折流板竖向推流反应器(baffled vertical plug flow,BVPF)中的厌氧发酵产气性能。结果表明,VPF反应器在有机负荷率(organic loading rate,OLR)为0.5gVS/(L·d)时运行良好,但提高OLR会出现出料困难的问题。CSTR有搅拌装置,所以反应器能够快速达到产气平衡。在OLR为1gVS/(L·d)时,BVPF达到稳定所需时间比CSTR多7天,但最终趋于稳定时CSTR和BVPF反应器的单位挥发性固体(volatile solid,VS)的日产气量分别为390.9mL和382.4mL。在OLR为2gVS/(L·d)时,BVPF达到稳定所需时间仅比CSTR多2天,稳定时CSTR和BVPF反应器的单位VS日产气量分别为291.3mL和294.9mL。此外,3种反应器在运行阶段,pH和VFA/TIC值都能维持稳定。在提高OLR后,BVPF和CSTR能够达到新的平衡状态。本实验结果表明VPF反应器只能用于低OLR的情况;CSTR达到稳定状态所需的时间较短,但CSTR和BVPF在稳定运行时的产气效率基本持平。由于BVPF的耗能量、耗水量低,因此该类反应器有良好的商业应用前景。