基于人工神经网络的MBR膜污染研究现状

膜生物反应器(MBR)是膜分离技术与生物处理技术相结合的一种新型、高效的污水处理技术,当前膜污染已成为限制MBR工艺推广应用的主要问题.分析了当前MBR膜污染规律的研究现状,指出了现有研究的不足,明确了人工神经网络(ANN)方法运用于MBR膜污染规律研究的优势.对ANN模型在MBR膜污染研究中的应用案例进行系统梳理,阐明了该方法在MBR膜污染研究领域的发展方向,为ANN模型在MBR膜污染研究领域的应用提供依据和参考.     

计算流体力学在膜技术及膜生物反应器研究中的应用

介绍了计算流体力学(CFD)的基本原理、内容和特点,综述了CFD在膜技术领域中的研究和发展,特别讨论了其在膜生物反应器(MBR)技术中的研究和应用,并对其应用前景进行了展望.     

EPS及其测定方法分析

膜污染问题一直是限制MBR(Membrane Bio-Reactor,膜生物反应器)发展和应用的一个瓶颈,而EPS(Extracellular Polymeric Substance,胞外聚合物)则被认为是MBR膜污染中的优先污染物.文中概括地介绍了EPS的类型、空间结构、对活性污泥特性的影响以及其与膜污染的关系,并对MBR中EPS提取及分析方法进行了综述,以期更全面的认识EPS特性,对实际运行的MBR工艺研究及膜污染控制等提供一定的理论依据.     

膜过程强化和组件放大的CFD应用

膜分离作为21世纪最具前景的高新技术之一,已广泛应用于化工、环境、生物、医药、电子等领域.然而,能耗高、产量低和寿命短三大问题始终制约着膜组件的应用.寻求合适的方法研究膜组件非理想流动下的传递过程,可用于指导膜组件放大和性能提升.计算流体力学(CFD)作为继量纲分析法和模型法之后一种新兴的化学工程研究方法,已被广泛应用于膜分离领域.本文以膜单元为对象的过程强化研究和以组件为对象的设备放大研究两方面综述了膜分离CFD模拟的最新进展.前者归纳了中空纤维膜、卷式膜和平板膜CFD研究所采用的模型和处理方法;后者总结了中空纤维膜组件三维CFD模拟的简化策略.然后提出两类CFD研究应着重发展的方向.最后根据CFD和膜技术的发展路线,预测两者在未来的结合将更加紧密.     

PAC-MBR组合工艺在水处理中的应用研究现状

膜生物反应器(MBR)技术目前已在水处理领域得以广泛的研究和大规模的应用,为了进一步扩大该技术的应用领域并有效的控制其膜污染问题,粉末活性炭-膜生物反应器(PAC-MBR)组合工艺成为MBR技术领域的研究热点之一.在介绍PAC-MBR组合工艺原理的基础上,详细论述了投加PAC对该工艺的关键运行参数和膜污染的影响,以及该组合工艺在水处理领域中的应用现状,并展望了该技术的研究及应用前景.     

颗粒物质控制膜污染的增强型膜生物反应器工艺的研究

用于废水处理的膜生物反应器工艺(MBR),是指通过膜过滤实现活性污泥与产水的分离的新型生化法处理废水技术.由于MBR具有占地面积小和出水水质好的优点,膜生物反应器成功应用到废水处理中的案例正在迅速增加.膜污染是MBR废水处理工艺面临的主要问题之一.膜污染会导致膜的渗透性能降低,为此必须通过化学清洗才能恢复膜的性能.为了实现无化学清洗的MBR工艺,研究使用持续物理冲刷去除膜污染层的方法.在活性污泥中加入颗粒物质(粉料),通过这些颗粒物质的持续冲刷作用实现去除膜污染层的目的.经过8个多月的实验,膜组件的渗透性能保持不变,通量可以达到40 L/(m2.h)以上.系统安装了在线的浊度仪作为产水质量的检测,在试验过程中,浊度始终没有变化.作为对比,同时也进行了一个参照实验(MBR标准工艺,没有加入颗粒物质),实验结果表明,传统的MBR工艺的膜组件渗透性能会不断下降导致通量下降,需要进行化学清洗.新型MBR工艺高通量和无需化学清洗的优势,将极大地提高MBR工艺的成本效益.     

气升循环分体式MBR的CFD模拟及优化

基于计算流体力学(CFD)方法,对气升循环分体式膜生物反应器(AL EC MBR)的关键结构参数与水力学参数的相关关系进行了模拟、优化和敏感性分析.研究结果表明,增加气液混合高度和曝气元件数量可提高混合液的混合程度及膜面流速、剪切力分布的均匀性,有利于膜污染控制;曝气器位置升高会使MBR流场分布的均匀性下降;混合液黏度的增加会降低混合液循环流速,但使膜组件中气液混合流的均匀度提高.在MBR膜组件中存在着混合液流速和剪切力分布中部区域高外部区域低的不均匀性,这种不均匀性是导致膜有效利用面积降低和水处理成本升高的重要流体力学因素.     

计算流体力学在纳滤膜分离技术研究中应用

介绍了计算流体力学(CFD)在膜分离过程模拟中的基本原理,探讨了CFD在膜隔网优化设计、纳滤膜污染机理研究、纳滤膜对无机离子截留等领域中的应用,并对CFD在纳滤膜分离技术研究中的应用前景进行了展望.     

计算流体力学对膜生物反应器水力学特征的模拟研究

通过计算流体力学(CFD)中的FLUENT软件,对膜生物反应器内流场和流态进行模拟,定量给出了其流速与剪切力的分布.研究了膜组件距离反应器底部不同距离时的水力学情况和水力学条件.对比了膜生物反应器中,玻璃纤维编织管式膜组件与平板膜组件,由于构型不同所导致的水力学条件差异.结果表明,从雷诺数和质量流速率参数分析,玻璃纤维编织管式膜组件的水力学条件更好,更有利于膜污染的防治.探讨了单个与多个曝气器情况下的流速分布,结果表明,后者流速分布更为均匀.由本文研究结果可知,计算流体力学可以作为一个有力的工具应用于MBR及其膜污染控制研究中.     

气升循环分体式MBR中H循环管水力学研究

以气升循环分体式MBR为研究对象,采用计算流体力学数值模拟方法,展开H循环管水力学条件优化研究.对H循环管的作用及H循环管管径大小的影响进行了模拟分析,并推导出H循环管循环流速U的计算公式.结果表明,H循环管对于气升循环分体式MBR具有必要性;膜单元与生物单元之间的循环流量随H循环管管径增大而增大,而当D/L(H循环管管径/膜池回流口长度)=22.2%时,H循环管平均循环流速最大,循环效率较高;推导得出H循环管内流速计算公式为:U=1/n R2/3(H0/l)(Qa1/v1A1-Qa2/v2A2[])1/2.本文研究结果可为MBR水力学研究与气升循环分体式MBR研究与应用提供科学依据和参考.     

检定和校准证书的异同与应用

本文介绍了检定和校准以及证书的两点相同、五点不同之处,说明了对检定证书和校准证书的正确应用。     

Heat and Mass Transfer and Modeling and Prediction of Environmental Catastrophes

Basic definitions and concepts of the physicomathematical theory of natural catastrophes are given. Possibilities of mathematical modeling of natural and technogenic catastrophes are discussed in the context of the theory of heat and mass transfer and the mechanics of reacting media. The importance of taking into account conjugate heat and mass exchange in modeling catastrophes is emphasized. A formula for evaluating the probability of a collisional catastrophe is given.     

Multi-ferroic and magnetoelectric materials and interfaces

The existence of multiple ferroic orders in the same material and the coupling between them have been known for decades. However, these phenomena have mostly remained the theoretical domain owing to the fact that in single-phase materials such couplings are rare and weak. This situation has changed dramatically recently for at least two reasons: first, advances in materials fabrication have made it possible to manufacture these materials in structures of lower dimensionality, such as thin films or wires, or in compound structures such as laminates and epitaxial-layered heterostructures. In these designed materials, new degrees of freedom are accessible in which the coupling between ferroic orders can be greatly enhanced. Second, the miniaturization trend in conventional electronics is approaching the limits beyond which the reduction of the electronic element is becoming more and more difficult. One way to continue the current trends in computer power and storage increase, without further size reduction, is to use multi-functional materials that would enable new device capabilities. Here, we review the field of multi-ferroic (MF) and magnetoelectric (ME) materials, putting the emphasis on electronic effects at ME interfaces and MF tunnel junctions.     

CellML and associated tools and techniques

We have, in the last few years, witnessed the development and availability of an ever increasing number of computer models that describe complex biological structures and processes. The multi-scale and multi-physics nature of these models makes their development particularly challenging, not only from a biological or biophysical viewpoint but also from a mathematical and computational perspective. In addition, the issue of sharing and reusing such models has proved to be particularly problematic, with the published models often lacking information that is required to accurately reproduce the published results. The International Union of Physiological Sciences Physiome Project was launched in 1997 with the aim of tackling the aforementioned issues by providing a framework for the modelling of the human body. As part of this initiative, the specifications of the CellML mark-up language were released in 2001. Now, more than 7 years later, the time has come to assess the situation, in particular with regard to the tools and techniques that are now available to the modelling community. Thus, after introducing CellML, we review and discuss existing editors, validators, online repository, code generators and simulation environments, as well as the CellML Application Program Interface. We also address possible future directions including the need for additional mark-up languages.     

Synthesis and luminescent properties of alkali-metal and ammonium fluorosulfatozirconates and fluorosulfatohafnates

We have synthesized a variety of alkali-metal and ammonium fluorosulfatometallates (titanates, zirconates, and hafnates). The alkali fluorosulfatozirconates and fluorosulfatohafnates have been shown to exhibit efficient roentgenoluminescence (RL) in the UV through visible spectral region, with a maximum at 390–440 nm. Their RL spectra depend significantly on their composition (cation, anion, and water content), coordination of KF and K₂SO₄, and relative amounts of fluorine and SO₄ groups. We have examined the effect of heat treatment on the RL of these compounds. The rubidium and cesium fluorosulfatozirconates Rb₃Zr₂F₉SO₄ · 2H₂O, Cs₂ZrF₂(SO₄)₂ · 2H₂O, Cs₈Zr₄F₂(SO₄)₁₁ · 16H₂O, and Cs₂ZrF₄SO₄ offer the most efficient RL.     

The shape and stability of wall-bound and wall-edge-bound drops and bubbles

The behavior of wall-bound drops and bubbles is fundamental to many natural and industrial processes. Key characteristics of such capillary systems include interface shape and stability for a variety of gravity levels and orientations. Significant solutions are in hand for axisymmetric pendent drops for a variety of uniform boundary conditions along the contact line with gravity acting normal to a planar wall. The special case of a wall-bound drop or bubble that is also pinned at an edge (i.e. a ‘wall-edge-bound’ drop) is considered here where numerical solutions are obtained for interface shape and stability as functions of drop volume, contact angle, fluid properties, and uniform gravity vector. For a semi-infinite zero-thickness planar wall (plate), a critical contact angle is identified below which wall-edge-bound drops are always stable. The critical contact angle is computed as a function of the gravity vector. The numerical procedure, which makes no account for contact angle hysteresis, predicts that such wall-edge-bound drops are unconditionally unstable for any gravity field with a component that is tangent to the wall while inwardly normal to the edge. Select experiments are conducted that support the conclusions drawn from the numerical results.