应用群体感应淬灭技术控制MBR膜污染的研究进展

膜生物反应器(MBR)被广泛应用于污水的深度处理和回用。然而,膜表面的生物污染一直是MBR应用中的难题,至今仍未得到有效解决。研究结果表明,生物膜的形成与细胞间的群体感应(QS)有关,因此,通过干扰QS系统而阻止生物膜形成的群体淬灭(QQ)技术有望从根本上有效减缓MBR膜表面的生物污染。文中综述了微生物信号分子、QS机制以及各种控制MBR膜污染的QQ方法,为MBR膜生物污染控制技术的发展提供了相关信息。     

MBR膜生物污染的生物控制方法研究进展

膜生物反应器(MBR)因其具有出水水质优质稳定、剩余污泥少、运行控制灵活等优点,被广泛应用于国内外水处理领域。然而,膜生物污染是制约MBR进一步发展的瓶颈问题,一些研究者已尝试多种方法控制膜的生物污染,但都有其各自的缺陷。其中,通过利用微生物自身代谢来控制膜生物污染的生物控制策略,正得到人们越来越多的关注。回顾了生物污染的形成过程,总结了传统物理化学控制方法的缺点,同时介绍了近年来国内外膜生物污染的生物控制方法研究进展,包括酶降解法、群体感应抑制法、能量解耦法、一氧化氮诱导法、噬菌体法和D-氨基酸法。最后根据目前国内外的研究现状,展望了生物控制方法未来的研究前景。     

不同工艺类型的MBR膜污染行为解析

膜生物反应器(MBR)具有诸多优点,然而膜污染限制了MBR的广泛应用。从工艺类型来讲,水处理MBR工艺可分为好氧、厌氧和缺氧MBR。对于这三种类型的MBR,很少有关于其膜污染行为方面的直接比较。通过对比好氧和厌氧MBR在有机污染、无机污染、生物污染三方面的膜污染行为差异,阐明了造成不同膜污染的主要原因,同时对缺氧MBR的膜污染研究进行展望,为不同类型的MBR膜污染研究提供了理论依据。     

群体猝灭技术在控制MBR生物污染中的研究进展

膜生物反应器(MBR)广泛用于处理市政污水,但膜污染仍是MBR的应用瓶颈。基于微生物群体感应(QS)理论的群体猝灭(QQ)技术是一种具有较好前景的膜污染控制方法。QQ技术可干扰微生物的QS系统,进而抑制胞外聚合物的分泌和生物膜的形成,从根本上达到控制MBR生物污染的目的。对利用QQ技术控制MBR生物污染的研究进展进行总结,提出该技术面临的挑战,并对今后采用QQ技术减缓膜污染的研究进行展望。     

膜生物反应器在污水处理过程中的膜污染控制

在综合国内外大量文献的基础上,阐述了MBR膜污染的类型及其发展过程,针对膜污染的影响因素,提出了防止膜污染维持MBR膜长期稳定运行的主要控制条件、方法及MBR设计的注意事项,总结了当前膜污染最佳的物理化学清洗方法,指出今后要进一步注重高性能膜材料、新型膜生物反应器和工艺条件的研究,为MBR在我国的大规模应用作准备。     

基于群体淬灭理论MBR减缓膜污染研究进展

膜生物反应器(membrane bioreactor,MBR)已成为一个十分有前景的废水处理工艺,该工艺具有出水水质好、占地面积小等优势.然而,由于微生物附着在膜表面而发生的生物污染现象,致使出水通量下降,限制了MBR的大规模推广应用.最近,一种新兴的、基于群体感应(quorum sensing,QS)的群体淬灭(quorum quenching,QQ)技术在延缓MBR膜污染领域的应用备受关注.QQ通过干扰群体感应系统而阻止其所依赖信号分子的基因表达,从而可有效抑制膜表面生物膜的形成.本文首先介绍了群体感应机理,并根据不同的群体淬灭物质,归纳总结了群体淬灭技术在延缓MBR膜污染的最新研究进展,最后对该领域的研究进行了展望.     

影响反渗透膜生物污染的因素及控制方法

介绍了关于反渗透膜的生物污染影响因素,包括微生物自身特征,膜表面特征及操作条件等对生物污染薄膜生长的影响,叙述了反渗透膜生物污染的控制方法,提出了目前反渗透膜抗生物污染的三大防治手段所存在的问题。认为反渗透膜抗生物污染的研究依旧应以微生物在反渗透膜表面的形成过程及吸附机理为主,从而研发出更具有针对性的新型抗生物污染膜材料。     

膜生物反应器的污染及防治

控制膜生物反应器(MBR)的膜污染、提高膜清洗效率、延长膜运行周期,是影响MBR推广应用的至关重要的问题。现从膜、生物及运行条件等方面分析了膜污染的影响因素,并提出了MBR污染防治的相应措施。     

反渗透膜生物污染的研究进展

综述了近年来关于反渗透膜生物污染的研究进展。首先介绍了反渗透膜生物污染的机理,包括微生物与膜表面的吸附作用以及外界因素对微生物沉积的影响;然后阐述了如何监测和预警生物污染;并讨论了对生物污染的控制和预防方法,包括预处理、膜表面改性、膜清洗以及微生物群体感应抑制。     

群体感应抑制控制膜生物污染的研究进展

水中微生物及其代谢产物沉积吸附在膜表面,进而生长繁殖,形成了膜生物污染。膜生物污染的控制已经成为学者们研究的热点之一,而基于驱散群体感应体系对膜生物污染进行控制是国内外新兴的研究课题之一。本文综述了传统的膜生物污染控制方法,并阐述了基于驱散群体感应体系控制膜生物污染的研究新进展,并提出前景展望。     

中空纤维膜组件内纤维束间流体流动状况研究

建立了一套电导率仪──微机数据采集系统，采用脉冲示踪法，对一自制的二维膜组件模型内流体流动状况进行了研究，分析了开孔状况和操作条件对液体在膜件内停留时间分布的影响，提出了膜组件在结构设计和操作参数选择的原则和范围，对膜组件的设计和使用有一定的参考价值。     

中空纤维渗透汽化复合膜及组件研究进展

中空纤维渗透汽化膜组件具有器件小型化及成本较低等方面的优势,其工业应用潜力巨大。本文介绍了中空纤维渗透汽化复合膜及组件的研究进展,阐述了膜材料、成膜方法以及组件结构参数等对组件渗透汽化性能的影响,并对中空纤维渗透汽化膜组件的中试研究进行了总结。通过组件放大及中试研究发现,中空纤维渗透汽化膜组件的装填密度、长度以及抽吸方式均会影响其下游侧的真空度,从而影响其渗透汽化性能。膜材料的分子设计、组件的结构参数优化以及耐溶剂耐高温封装将是中空纤维渗透汽化膜组件未来工业放大过程中的关键环节。     

膜生物反应器膜污染的研究进展

从膜的结构性质、反应器操作条件、处理液微生物性质三个方面介绍了膜生物反应器膜污染机理研究的进展,总结了优化膜生物反应器设计、调节膜生物反应器操作条件、在线超声控制、化学方法等膜污染控制的常用方法,对未来膜污染研究进行了展望。     

Impact of module design on the performance of membrane bioreactors treating municipal wastewater

Membranes are located in a membrane module that physically seals and isolates the feed stream from the permeate flux in membrane bioreactors (MBRs). Therefore, module type, structure, and geometrical configuration are critical design considerations affecting membrane performance in MBRs. In this study, impact of membrane module design on treatment and filtration performance of MBRs was investigated. For this purpose, two flat sheet membrane modules with different outlet structures and module geometries, including rectangular- and D-shaped, were tested. In addition to the differences in outlet structure and module geometry, size of circular structures which supported membranes in rectangular- and D-shaped modules differed from each other. Considering the results, permeate quality was not affected from the change in the module design. However, the most remarkable impact of the module design was observed on the transmembrane pressure (TMP) evolution and fouling potential. D-shaped membrane module including smaller circular structures resulted in a decrease in fouling potential and thus, this module could be operated longer time in comparison to rectangular-shaped membrane module without a severe TMP increase. The observed differences in TMP increase and fouling potential lead to the hypothesis that module design is a critical factor affecting filtration performance in MBRs.     

Design and performance characterization of a new shear enhanced module with inbuilt cleaning arrangement

BACKGROUND: Shear enhanced membrane modules are becoming popular as they enable high permeate flux in almost all membrane filtration processes due to the high shear rate they generate at the membrane surface. In this article, the design of a new shear enhanced module with unique hydrodynamic cleaning facility is proposed. The device, presently at laboratory scale was named the Spinning Basket Membrane (SBM) module because of its inherent structural similarity with the well known Spinning Basket Reactor. An aqueous solution of polyethylene glycol was chosen as test fluid for the present study. RESULTS: The module was characterized under different parametric conditions of transmembrane pressure (TMP), feed concentration (C₀) and rotational speed of the basket (Ω). It was observed that with its inbuilt cleaning facility the module was able to restrict the flux decline to within 15% of its start up value, even after 21 h of continuous running, with a maximum initial flux as high as 612 L m^?2 h^?1. CONCLUSION: Based on the performance of the module, it may be concluded that this module could be scaled up for nearly uninterrupted industrial operation with reduced requirement for chemical cleaning, which is rare in the membrane industry to date. Copyright © 2012 Society of Chemical Industry     

Characterization of a New Flat Sheet Membrane Module Type for Gas Permeation

Modern high‐performance flat sheet gas separation membranes exhibit high permeances as well as high selectivities, e.g., for CO₂ separation. Novel membrane modules are desirable to transfer the intrinsic membrane performance to the process. The introduced module implements countercurrent flow, which allows for the best utilization of the required driving force, provided concentration polarization and pressure drops can be kept at bay. As such, it is different from established flat sheet modules for gas separation. The design features allow for straightforward scaling and easy adjustment to other operating conditions. During module development equation‐oriented modeling, computer‐aided engineering design and application of computational fluid dynamics for flow optimization were integrated. The prototype was investigated in a pilot plant. The experimental results reflected the simulation predictions and proved the validity of the module concept.     

Separation of greenhouse gases from gas mixtures using nanoporous polymeric membranes

Removal of greenhouse gases from gas streams using porous membranes was carried out in this work. Theoretical studies were performed in terms of mathematical modeling and numerical simulation of CO₂ capture in a flat‐sheet membrane contactor. Numerical simulation was performed using computational fluid dynamics (CFD) of mass and momentum transfer in the membrane module for laminar flow conditions. Physical absorption was considered in the simulations for absorption of CO₂ in pure water. CO₂ concentration distribution in the membrane module was determined through numerical solution of continuity equation coupled with the Navier‐Stokes equations. The modeling predictions indicated that the CO₂ concentration difference is not appreciable in the membrane direction. Moreover, velocity distribution was determined in the liquid side of membrane contactor. CFD also represents a design and optimization tool for membrane gas separation processes. POLYM. ENG. SCI., 55:975–980, 2015. © 2014 Society of Plastics Engineers     

新型气隙式膜蒸馏组件脱盐过程

利用基于聚丙烯中空纤维膜和聚丙烯中空纤维换热管的新型能量回收式膜组件(AGMD-HF),以70 g·L^-1的氯化钠溶液为研究对象,考察了膜组件长度和膜孔径大小对膜组件脱盐性能的影响。为直接衡量操作条件、组件参数以及温差、浓差极化现象对传质系数的影响,引入总传质系数,并研究进料温度和膜孔径对总传质系数的影响。实验结果表明,总传质系数随着温度的升高、膜孔径的增大而增大,提高膜孔径可有效提高总传质系数,同时可有效提高通量和造水比。通量随组件长度的增大而减小,而造水比增大,因此在应用过程中可综合考虑通量和造水比以便选择合适的组件长度。     

PULSED ELECTROCHEMICAL CLEANING OF INORGANIC MICROFILTRATION MEMBRANES

The effect of the application of pulsed electric fields during cross-flow microfiltration has been studied at two novel types of inorganic membrane. Pulsed electrophoretic membrane cleaning was shown to be a very effective, improving filtration rates at anodic film membranes (Anopore) by factors of up to 6.5 under the conditions studied. Improvements were also measured at zirconia membranes (Ceramesh). The incorporation of a mesh in these latter membranes allowed direct use of the membrane as an electrode, giving a potential simplification in module design. Application of a force balance model incorporating changes in the resistances to flow on application of the electric field showed that the likelihood of membrane cleaning depended on the interplay of two opposing phenomena of comparable magnitude-particle electrophoresis and membrane/filter cake electro-osmosis. However, due to the complexity of the phenomena involved, such an approach can not readily lead to a quantitative prediction of the effectiveness of membrane cleaning. KEYWORDS: Membrane, Filtration Microfiltration, Electrofiltration, Electrophoresis.     

Advantageous and detrimental effects of air sparging in membrane filtration: Bubble movement, exerted shear and particle classification

In various membrane applications air scour is applied to minimise fouling and to remove cake layers. Optimisation of module design and operating conditions (e.g., geometry and aeration intensity) requires knowledge of the most suited hydrodynamic conditions for the filtration task. However, many fundamentals of this multiphase flow in membrane modules are still unknown and difficult to access experimentally. Using experimental and numerical investigations it was shown that air sparging can have advantageous but also detrimental effects: depending on membrane plate spacing, wall shear can decrease with bubble size. Additionally, particle classification or segregation which increases the cake’s hydraulic resistance must be taken into account. Based on such findings, it will be possible to derive optimum bubble sizes, membrane spacing, aeration intensities and start-up strategies.