一体式厌氧膜生物反应器膜材质选择的试验研究

厌氧膜生物反应器作为一种处理高浓度有机废水行之有效的工艺,膜材质选择是保证其良好运行的关键之一.试验研究了一体式厌氧膜生物反应器中三种不同材质的膜PAN、PES和PVDF膜过滤特性.并通过数据拟合得出不同的膜通量和膜阻力随时间的数学模型表达式.结果表明,在相同的操作条件下,PAN膜通量维持在一个较高水平,膜污染速度增长缓慢,PAN膜是本试验条件下厌氧膜生物反应器的最佳膜材质.     

厌氧膜生物反应器(AnMBR)处理高浓度豆制品废水的研究

采用膨胀污泥床反应器与外置管式超滤膜组成厌氧膜生物反应器(AnMBR)处理高浓度豆制品废水,实验连续运行240d,AnMBR平均处理量30～160L/d,研究了反应器的处理效果并获得了最佳水力停留时间(HRT).实验结果表明,AnMBR处理高浓度豆制品废水能够达到较好的效果,当进水COD为10g/L左右时,最佳HRT为18h,COD去除率约90%,此时相对应的有机负荷(OLR,以COD计)为13.6kg/(m3.d);稳定运行期间,单位COD气体产率为0.10～0.25L/g,甲烷含量在70%左右:在0.1MPa操作压力条件下进行膜的运行试验,考察了不同清洗方式的效果,采用最佳清洗方式膜通量可以恢复到新膜的90%左右.     

TiO_2动态改性膜应用于MBR的研究

采用二氧化钛(TiO_2)纳米粒子对聚偏氟乙烯中空纤维膜微滤膜(PVDF MF,0.1μm)和实验室自制聚砜中空纤维膜超滤膜(PSF UF,0.05μm)进行表面亲水改性,以期提高膜的抗污染能力.采用膜接触角、纯水通量、出水TOC、膜压差和扫描电子显微镜(SEM)进行表征了TiO_2动态膜的性能.将TiO_2纳米颗粒改性后的PVDF MF和PSF UF膜应用于膜生物反应器(MBR)处理模拟焦化废水(TOC=500 mg/L),考察了其对MBR过滤性能的影响.实验结果表明,改性后膜的水接触角明显减小,亲水性增强,TMP升高速率明显降低,模拟焦化废水,TOC的去除率平均可达95%,经返洗及次氯酸钠清洗后膜表面TiO_2层外观没有明显变化.改性后的膜组件较显著地增加了MBR的膜抗污染的优势,且具有一定的稳定性.因此,将TiO_2动态改性耐污染膜应用于MBR是可行的.     

颗粒悬浮填料复合式膜生物反应器的过滤性能研究

介绍了颗粒填料复合式膜生物反应器(HMBR)在工业废水处理中的应用.在运行条件一致的情况下,对普通膜生物反应器(MBR)和颗粒填料复合式膜生物反应器(HMBR)进行了对比实验,着重研究了颗粒填料在膜污染控制方面的作用.结果表明:由于投加填料颗粒,HMBR的沉积层阻力减少了86%,临界通量增长了约20%;在长期运行过程中MBR的膜污染速率是HMBR的3.3倍.在膜生物反应器中投加颗粒填料可以有效地改善其过滤性能,减缓膜通量的下降.     

动态膜生物反应器(DMBR)研究进展

动态膜生物反应器是一种将动态膜过滤技术和生物法污水处理工艺相结合的新型污水处理工艺.介绍了DMBR机理及工艺处理效果,并从膜基材选择、操作参数控制等方面评述了国内外学者在该领域的研究成果,指出DMBR存在的问题及发展方向.     

Studies of a membrane aerated bioreactor for wastewater treatment

This study was undertaken specifically to collect engineering and process performance information on the behaviour of a membrane supported bio-film in a well-characterised bioreactor. A novel membrane aerated bioreactor has been tested in the laboratory on synthetic sewage, and also piloted for the treatment of primary effluent at a local municipal wastewater treatment plant. The reactor's design employs gas-permeable, hollow-fibre membranes that are submerged in the wastewater. Air is blown through the inside of the fibres. Aeration costs for such a reactor are likely to be lower than conventional systems because gas compression is not required. Thick bio-films grow on the outside of the fibres and effectively treat the wastewater. The bio-films grown in this manner are capable of biological oxygen demand (BOD) removal, nitrification, denitrification, and simultaneous sludge digestion. The character of the bio-film is very different from conventional bio-films grown on inert surfaces, since in this case the bio-film receives its oxygen and the wastewater components from different directions. In pilot studies, a reactor having a hydraulic residence time of 6.5 h and equipped with no sedimentation tank achieved 70–75% BOD and nitrogen removal, and produced an effluent containing less than 30 mg/l total suspended solids.     

Studies on the use of hollow fibre membrane bioreactors for tissue generation by using rat bone marrow fibroblastic cells and a composite scaffold

Production of sufficient tissue in vitro for use in tissue engineering is limited mainly by the absence of adequate oxygenation and appropriate transport of nutrients to, and waste product from, the tissue. To overcome the limitations of diffusive transport, the possibility of growing three dimensional (3D) tissue structures by using hollow fibre membrane bioreactors (HFMB) has been considered in this study. The hollow fibre membranes, embedded in the 3D scaffold, are porous and semi-permeable and can thus serve similar functions to arteries and veins in vivo. Collagen gel and Cytodex 1 microcarriers were used as a composite 3D scaffold and permeating cellulose acetate hollow fibre membranes were attached to both ends of a polycarbonate cylindrical shell to form a bioreactor. Rat bone marrow fibroblastic (RBMF) cells were seeded initially onto Cytodex 1 microcarriers and these were subsequently mixed with collagen gel before inoculation into the bioreactor. Bioreactors were perfused by culture medium through the hollow fibre membranes for a one week period. Bioreactors containing cells cultured under similar conditions except for the lack of perfusion of medium served as controls. The proliferation, viability, metabolism and morphological appearances of the cells in the perfused and non-perfused constructs were compared. The results indicated that there was significantly greater maintenance of functional activity and normal cellular morphology in the perfused group than in the non-perfused group. Further studies are required to evaluate the additional advantages of using this novel HFMB for growing 3D dense tissues.     

废水处理中膜生物反应器的研究进展

膜生物反应器作为一种新型高效的生物处理技术和绿色技术,在水处理领域中得到了广泛的应用.综述了膜生物反应器在全世界的研究现状,膜生物反应器的构型、好氧膜生物反应器和厌氧膜生物反应器及应用情况,膜污染控制技术.探讨和展望了膜生物反应器的应用前景,指出了今后的研究方向.     

Preparation and characterization of phosphorylated Zr-doped hybrid silica/PSF composite membrane

Polysulfone (PSF) membranes are broadly applied in many fields owing to good physicochemical stability, resistance to oxidation and chlorine. But when treated with wastewater containing oil, PSF membranes are easy to be contaminated for its hydrophobicity, which can result in the declining of flux and lifespan of the membrane and limit their application in large scale. To enhance the capability of PSF membrane in the above circumstances, phosphorylated Zr-doped hybrid silica particles (SZP particles) were firstly prepared. SZP particles have various point defects inside their structure and lots of hydroxide radicals on their surface. SZP particles were added to the porous matrix of PSF to prepare a novel composite membrane (SZP/PSF) through a phase inversion process. Finally, the optimum preparation conditions of SZP/PSF composite membranes were determined. The optimum conditions are: the mass ratio of PSF, PEG400 and SZP is 12:10:10; ultrasound 10 min inside each 30 min; the pre-evaporating time is 10s. Optimized SZP/PSF composite membrane was characterized by scanning electron microscope (SEM) and ultrafiltration experiment. The results indicate that SZP particles can be uniformly dispersed in SZP/PSF composite membranes with excellent hydrophilic property, antifouling capability and tensile strength. Therefore, it can be concluded that the optimized SZP/PSF composite membrane is desirable in the treatment of wastewater containing oil and wastewater.     

Working without accumulation membrane in flow field-flow fractionation

Nonideal interaction of sample with the separation device is a difficulty found in chromatographic methods as well as in field-flow fractionation. However, in field-flow fractionation (FFF), greater flexibility in the choice of carrier solution composition is possible, thus reducing the need of a wide choice of surface chemistry when nonideal sample interaction is to be minimized. The use of an ultrafiltration membrane as the surface for the accumulation wall is common practice in flow field-flow fractionation. Typical membranes in use are laminates of a skin membrane onto a backing material such as woven polyester. At this point, only a limited choice of membrane chemistries is available. Many membranes have been developed for protein applications as membranes are widely used in the pharmaceutical industries. While these membranes work well for protein applications, flow field-flow fractionation is applicable to polymeric particulate as well as protein samples. Thus, sample interaction with the membrane surface is possible with nonprotein applications and these interactions can induce significant secondary effects on retention ratio and affect instrumental reliability. Also, the woven texture of membranes may detrimentally affect the FFF separation. For these reasons, the study of flow field-flow fractionation using a flat, smooth surface of controlled chemistry is of relevance. We present here the results of a new, membraneless channel that uses a bare frit as the accumulation wall and that is intended for analysis of micrometer-sized particles only. Selectivity results are comparable to those obtained with the membrane, while relative sample recovery indicates that the best quantitative performance can be obtained without the membrane. Moreover, neither sample immobilization nor losses through the frit occur when operating membraneless. On the other hand, first experimental evidence of a certain level of frit surface activity suggests that optimization of experimental conditions is required.     

厌氧膜生物反应器在食品废水处理中的应用研究

分别采用小试规模(50 L/d)外置错流管式厌氧膜生物反应器和中试规模(20 t/d)浸没式厌氧旋转膜生物反应器进行了食品厂废水的处理实验研究.结果表明,加入超滤膜单元提高了厌氧系统的总有机物去除率及甲烷产量,使系统出水水质更加稳定;外置错流式超滤膜随运行时间的延长通量明显下降,而旋转式超滤膜可通过膜片旋转速度提高和保持膜通量;浸没式旋转膜组件的运行能耗较外置管式膜组件至少降低30%;但不同形式的厌氧膜生物反应器对氨氮和总磷去除能力有限,需进一步处理.     

Axial wave propagation in membrane shells of revolution

The dynamic finite element technique, which is referred to in the literature as ‘computer-analysis’, is applied to wave propagation problems occurring in finite and semi-infinite linearly elastic membranes of revolution. Both semi-infinite and finite versions of cylindrical and conical membranes are considered, and a finite membrane having a meridional curve which is parabolic is solved. The source of excitation is generally a constant velocity motion of one end of the membranes, but the results for a stress-pulse input at one end of a semi-infinite cylindrical membrane are also given. The results for the finite membranes are new, and the results for the semi-infinite problems are discussed with respect to previously published results. The two-dimensional state of stress in the membrane requires careful ordering of the calculations, and the boundary conditions for finite membranes are shown to follow logically from this ordering of the calculations. The difference in the solutions resulting from prescribing an axial or a tangential velocity excitation at the end of a conical membrane is presented, and the mesh size necessary for convergence to the solution is indicated. The graphs of the results clearly indicate regions in space and time where the membrane model should be replaced by the shell formulation to represent a realistic structure. The technique is shown to be self-contained and independent of any formal method such as the method of characteristics.     

纳滤膜分离洁霉素生产废水的试验研究

针对洁霉素生产废水,采用国内外多种纳滤膜在不同工况条件下进行了试验研究,筛选和确定了适用纳滤膜的种类和其最佳工作条件,为纳滤膜的进一步应用奠定了基础。     

废弃聚偏氟乙烯中空纤维膜再生与回用性能

研究了经膜生物反应器(MBR)系统运行6年的废弃聚偏氟乙烯(PVDF)中空纤维膜再生回用性能。讨论了运行过程中膜污染对PVDF中空纤维膜的影响;采用溶液相转化法制备了再生PVDF平板膜。研究结果表明,经运行6年后,PVDF中空纤维膜中致孔剂(如聚乙二醇(PEG)或聚乙烯吡咯烷酮(PVP))含量减少至零,断裂强度降低,断裂伸长率减小,相对分子质量降低,结晶度升高,膜孔堵塞等现象明显;与常规PVDF膜相比,再生PVDF膜的断裂强度和断裂伸长率较小,成膜过程中致孔难度增大(孔隙率较低),而再生PVDF膜的润湿性、渗透性以及截留率等与常规PVDF膜相近。     

膜生物反应器用于城市污水处理与回用的试验研究

采用规模为40m^3／d的膜生物反应器对城市污水处理回用进行了试验研究．试验结果表明：膜生物反应器具有较强的抗冲击负荷能力，活性污泥对污染物的去除起主要作用，膜分离对维持稳定的出水起重要作用．膜生物反应器出水稳定，水质良好，优于生活杂用水水质标准(CJ25．1—89)．     

Controlled growth of CNT in mesoporous AAO through optimized conditions for membrane preparation and CVD operation

Anodic aluminium oxide (RAAO) membranes with a mesoporous structure were prepared under strictly controlling experimental process conditions, and physically and chemically characterized by a wide range of experimental techniques. Commercial anodic aluminium oxide (CAAO) membranes were also investigated for comparison. We demonstrated that RAAO membranes have lower content of both water and phosphorus and showed better porosity shape than CAAO. The RAAO membranes were used for template growth of carbon nanotubes (CNT) inside its pores by ethylene chemical vapour deposition (CVD) in the absence of a catalyst. A composite material, containing one nanotube for each channel, having the same length as the membrane thickness and an external diameter close to the diameter of the membrane holes, was obtained. Yield, selectivity and quality of CNTs in terms of diameter, length and arrangement (i.e. number of tubes for each channel) were optimized by investigating the effect of changing the experimental conditions for the CVD process. We showed that upon thermal treatment RAAO membranes were made up of crystallized allotropic alumina phases, which govern the subsequent CNT growth, because of their catalytic activity, likely due to their Lewis acidity. The strict control of experimental conditions for membrane preparation and CNT growth allowed us to enhance the carbon structural order, which is a critical requisite for CNT application as a substitute for copper in novel nano-interconnects.     

Mechanical failure of human fetal membrane tissues

Mechanical integrity of the chorioamnion membrane, and the component chorion and amnion layers, was assessed with biaxial puncture testing. Fetal membranes were obtained from term placentas following labored natural delivery or scheduled cesarean section. Preterm specimens were obtained from deliveries prior to 37 weeks gestation. Dividing and peripheral membranes were obtained from multiple gestation pregnancies. Specimens were gripped between parallel plates with circular openings and loaded with an instrumented, hand-held blunt probe until rupture occurred. Peak force was recorded and rupture sites were examined. Defects in multi-layered membranes differed in both size and shape in the individual layers. Compared with chorion and whole chorioamnion, amnion was more mechanically sensitive to different obstetrical conditions. Amnion varied in response at different physical locations within the same patient. Membrane and component puncture force data were used to calculate biaxial failure strength. Membrane stresses arising from amniotic fluid pressure were computed as a function of gestational age, and compared to membrane strength to examine the criterion for membrane failure in vivo. Possible mechanical conditions for preterm membrane rupture were examined.     

浸没式双轴旋转厌氧膜生物反应器的膜污染机理研究

试验研究了新型浸没式双轴旋转厌氧膜生物反应器处理啤酒废水的膜污染机理.分析了膜阻力分布情况和膜污染速率及稳定运行时膜过滤阻力随运行时间变化的阻力模型.结果表明,最初很短时间内膜污染受膜孔堵塞模型控制,之后受泥饼层阻力模型控制,后一阶段是膜污染的主要控制阶段.经过146天的运行,膜污染较轻,过滤阻力随时间增大的速率非常缓慢,并在一定膜转速下,过滤阻力保持不变.证实了系统由双轴旋转膜组件形成的湍流可削弱膜表面的浓差极化及泥饼层的形成,从而有效地控制膜污染.     

表面光接枝技术及其在分离膜中的应用

与其它方法相比,膜分离因具有分离效率高、操作过程简单、能耗低、没有环境污染等特点而成为各个行业不可缺少的技术．随着科学技术的进步及分离膜应用范围的拓宽,对分离膜的性能要求越来越高;一些不单以分离为目的的膜技术的出现,则要求有与之相适应的功能性分离膜,所有这些问题都急需解决．将表面光接枝方法引入到分离膜技术中,改善传统膜的性能,制备新型功能性复合分离膜,已成为一个具有很大希望的领域．     

超滤膜生物反应器处理生活污水的试验研究

用外压一体化中空纤维超滤膜生物反应器（ＵＭＢＲ）进行了处理生活污水的试验．结果表明,当水力停留时间（ＨＲＴ）为５ｈ、膜通量在４４２～１１０Ｌ／ｈ时,ＵＭＢＲ对生活污水中ＣＯＤ、浊度、ＳＳ的去除率分别可达９０％、９８％、１００％,出水ＣＯＤ＜６０ｍｇ／Ｌ、浊度＜３、ＳＳ为０,污泥质量浓度ρＭＬＳＳ、污泥负荷Ｆｒ、反应器容积负荷ＦＷ分别为６２ｋｇ／ｍ３、０４６ｋｇ／（ｋｇ·ｄ）、１８２ｋｇ／（ｍ３·ｄ）．初步探讨了超滤膜的堵塞机理,通过杀菌清洗可使超滤膜通透能力恢复到新膜的９７％以上．ＵＭＢＲ出水浊度低,水质稳定,宜于回用