一种直接从生物膜中萃取细胞外高分子有机物的方法

引言 生物膜(biofilm)是由微生物、细胞外高分子有机物(EPS)和惰性物质构成的多孔介质.最近研究发现,EPS的组成和含量不仅影响生物膜的内部结构和微生物活性,而且对基质在膜内的传质机理也有较大影响[1,2].为了深入了解EPS对传质过程的影响,许多生物膜工作者都设法从生物膜中萃取出EPS.然而到目前为止,几乎所有的萃取方法都需要首先把生物膜破碎[1].由于生物膜已遭破坏,所以进一步深入研究生物膜的结构特性、基质在生物膜内的传质机理几乎无法进行.     

电场对离子在微孔滤膜中传质的影响

本文研究了外加电场对离子在微孔滤膜中传质的影响,实验测定了不同电场强度下的铵离子浓度随时间的变化曲线。结果表明：正向电场会加速离子的运动从而提高离子的传质速率。     

电场和提取剂对提取胞外聚合物的影响

本文研究了电场和提取剂对胞外聚合物提取效果的影响,实验测定了在交流电场下不同的提取剂如：NaOH、EDTA、Tris和硫酸对提取液中的多糖含量,结果表明,电场和提取剂对提取效果有明显影响。     

高频电场对微生物传质影响的静态实验研究

为探索高频电场抑垢缓蚀机理,采用自制的高频电场装置,对含有微生物的自来水水质进行加高频电场处理静态金属挂片对比实验,考察了高频电场对黏液形成菌和铁细菌的传质过程及该水质中碳钢腐蚀速率的影响情况。在一定实验条件下(30℃恒温培养,静止),分别对未加电场处理和加电场处理实验水质的细菌总数、p H值、氧化还原电位(ORP)、电导率、碳钢挂片腐蚀速率等参数进行检测分析。实验结果表明:高频电场对上述各水质参数的变化情况和微生物传质有一定影响,高频电场破坏了微生物的生存环境,使其生长特性发生了改变,抑制了微生物的繁殖;对含有微生物的水质中金属的腐蚀也有抑制作用,因此,高频电场具有良好的抑菌、抑垢、缓蚀性能,在循环冷却水系统中具有广阔的应用前景。     

电场强化臭氧向水中传质的试验研究

首次提出了利用电场强化臭氧向水中传质过程的方法,结果表明:电场能够强化臭氧向水中的传质过程,而且效果和电场的强弱有关,试验中所加电压越高,对于传质的加强效果越明显。当电压为8kV时,和没有电场的情况相比,总传质系数提高41%。该方法为研究臭氧向水中的传质提供了新的途径。     

硅橡胶复合膜用于渗透蒸发的膜传质动力学(Ⅱ)膜内的扩散传质

The pervaporation of organics from dilute aqueous solution through a novel plate composite silicone rubber membrane was investigated. The measured and derived data indicated that the composite membrane possessed very high permeation flux and stable selectivity for dilute organic aqueous solution. Based upon the well- known resistance-in- series model, diffusive mass transfer behavior in membrane was investigated by calculation from the measured data with different skin layer thickness of membranes. The experimental results showed that the diffusive mass transfer coefficient conformed to Arrhenius correlation with temperature and was independent of the flow status. The diffusivities of the given alcohols in membrane had an order of magnitude 10 m-10·s-1 at a wider range of temperature, which is similar to those reported in literatures.     

生物膜方法处理重金属离子有机废水研究进展

介绍了生物膜法处理重金属离子废水的作用机理及成膜过程,对国内外生物技术处理废水的方法进行了综述,并同时提出了生物膜法与其他处理方法的复合工艺的研究方向及展望.     

生物膜吸附重金属离子的模型及影响因素的研究

重金属是对生态环境危害极大的一类污染物。去除废水中的重金属元素,生物膜法是一种有效的净化工艺。为了寻找生物膜去除重金属离子的最优操作条件,考察了各种影响因素pH值、温度、吸附时间、生物膜量、共存离子对吸附的影响。从实验结果可知,Cu2+的最优操作条件是pH值为6,温度在30℃左右,吸附时间为15min,生物膜量为12g,吸附率可达到65%;Cr3+的最优操作条件是pH值为3～7,温度在25℃左右,吸附时间为5min,生物膜量为10g,吸附率可达到87%。共存离子的竞争吸附会对吸附能力弱的Cu2+产生很大的影响,Cr3+没有表现出受到抑制或促进作用的影响,对单一Cu2+或Cr3+吸附体系,可以用经典的吸附模型进行拟合。     

电场强化铜矿排土场氧气传质

在排土场微生物浸出过程中,通过电场作用下的气泡受力分析和强化传质实验,首次提出了利用电场强化氧气向溶浸液中传质过程的方法,结果表明：电场能够强化氧气向溶浸液中的传质过程,而且效果和电场的强弱以及浸矿溶浸液的性质有关;实验中所加电场强度和溶浸液浓度越高,电场强化传质的效果越明显。传质速率的大小和传质系数、气泡大小、气泡在水中的运动、气液比以及气相氧气的质量浓度等因素有关。在强度为80 V·mm^-1的电场作用下,和没有电场的情况相比,总传质系数提高28. 2%。     

生物膜胞外聚合物在废水处理中的作用

本文详细地叙述了近年来生物膜胞外聚合物在处理废水中的重金属、生物膜传质方面的作用。     

The Effect of Electric Field on Heat and Mass Transfer

The process of evaporation from flat and cylindrical surfaces into an air stream flowing tangentially to them has been experimentally investigated. An electric field has been induced in the system from an emitting electrode in the form of needles arranged in a plate placed above the grounded water surface. A decisive effect of the ion-drag force on the evaporation process has been confirmed in the experiments proving that the ionic wind had intensified the process. About 8-fold increase in the average values of the heat and mass transfer coeficients caused by an electric field of an intensity 5 kV/cm in comparison with those obtained without the field has been observed. General correlations relating the evaporation rate to the process parameters have been suggested.

The system under consideration can be treated as a model one for a solid dried at a constant rate period. The drying experiments with a kaolin plate have been carried out under conditions corresponding to those applied in water evaporation from a flat surface to provide the same values of the heat and mass transfer coefficients. Intensification of the drying process by the electric field, similar to that of water evaporation, has been recorded.     

Effect of External Recycle on Mass Transfer in Countercurrent Double-Pass Cross-Flow Rectangular Dialyzers

A study on mass transfer in countercurrent cross-flow rectangular dialyzers with external recycle was investigated. Theoretical analysis of mass transfer in cross-flow dialyzers is analogous to heat transfer in cross-flow heat exchangers. In contrast to a single-pass cross-flow device without recycle, improvement in mass transfer of about 30% is achievable if a double-pass device of the same size with external recycle is employed, which provides the increase of fluid velocity, resulting in increase of mass-transfer coefficient. Higher effectiveness may be expected when dialysis is operated for the system in which the mass-transfer resistances in the liquid films are comparable with that in the membrane.     

Effect of External Electric Field on the Grain-Growth Behavior of Barium Titanate

The effect of an external electric field on the grain-growth behavior of acceptor Mg-doped, undoped, and donor Nb-doped BaTiO₃ ceramics was investigated. The acceptor-doped and undoped specimens showed enhanced grain growth at the positive-biased region. On the other hand, for the highly donor-doped specimens, grain growth was enhanced in the negative-biased region. The results have been explained in terms of defect polarization and the consequent change in the boundary potential. It has been suggested that liquid penetration into grain boundaries is critically dependent on the boundary potential.     

复合塔板传质性能研究

在内径为 76mm的玻璃塔内 ,以乙醇 -水为试验物系 ,研究了复合塔板的传质性能。研究表明传质主要在塔板上的泡沫区及填料段的液膜区内进行 ,而淋降区的贡献甚小 ,并研究了影响复合塔板传质性能的诸因素 :塔板开孔率、孔径、填料类型及填料高度等 ,结果对复合塔板的设计具有一定的指导作用。     

The Effect of External Mass Transfer Resistance during Drying of Fermented Sausage

The drying mechanism of fermented sausages (sucuks) that were cylindrical rod shaped, 40 cm long and 4 cm diameter, during ripening under natural convection conditions at different temperatures (15 to 30°C) was examined. To simulate the experimental drying curves, three empirical models and a diffusional model assuming negligible external mass transfer resistance were evaluated. The drying rate curves of sucuk samples were also simulated taking into account the influence of the external mass transfer resistance. The equation was solved using the trial-and-error solution algorithm developed in this study and the mass transfer coefficient, k _c , and effective moisture diffusivity, D _eff , were simultaneously determined (1.44 × 10^?8 to 1.93 × 10^?8 m/s and 4.30 × 10^?10 to 6.85 × 10^?10 m²/s, respectively). The proposed model considering the effect of external resistance allowed the accurate simulation of the experimental drying data of sucuks at different temperatures.     

新型复合填料塔的传质性能研究

本文提出一种新型的复合填料塔设备,将穿流筛板引入到填料塔中。同普通填料塔相比,复合填料塔优化了液体分布和再分布装置,节省了大量空间,压降低,穿流筛板本身又有优良的传质性能,因此具有比普通填料塔更好的性能。并对复合填料塔传质性能进行了测定和关联,得到了传质性能基础数据,可为复合填料塔的设计应用提供参考。     

生物膜技术原位处理有机污染河道研究

将生物膜技术移植到有机污染河道治理中,采用三种生物填料,与目前最常用的空曝气技术对比净化有机污染河道的效果.结果表明:污染河道底泥具有较强的生物活性,可以用作净化污染河道的作用主体.挂膜过程中四组反应器对有机物、氨氮的降解速率相当;挂膜过程结束后,三组生物膜反应器中的水质净化效率高于空曝气反应器.通过对底泥中有机成分的对比分析,发现经过9d连续运行后,四组反应器底泥中的有机质含量分别由最初的12.21%降低至9.42%、7.24%、6.97%和7.52%,表明生物膜技术在净化污染水体的同时,对污染底泥中的有机物也具有更为有效的降解效果.     

场协同对PP/PS复合体系传热传质性能的影响

从动量和能量守恒方程出发,提出速度场与温度场的协同耦合作用对聚合物流动与换热具有重要影响,并以此为依据设计了新型扭转螺杆结构和场协同螺杆。以聚丙烯(PP)和聚苯乙烯(PS)为原料制备PP/PS复合材料体系,通过挤出试验对比研究了常规螺杆与场协同螺杆的传热传质性能。结果表明,相对于常规螺杆,设置有扭转螺杆结构的场协同螺杆的数均粒径更小、粒径分布密度和平均停留时间更大,提高了挤出机的混合能力;场协同螺杆的对流换热系数更大、径向温差更小,提高了挤出机的换热能力。