Modelling and Control of Membrane Fouling in Ultrafiltration of Water and Wastewater

膜过滤，如超滤（UF），是一种高效节能的工艺，已广泛应用于水净化、废水处理、生物技术、油包水乳化液分离等领域。然而，由进料溶液中的溶质/颗粒引起的膜污染是行业面临的主要挑战，并且存在操作问题，目前阻碍了膜过滤的广泛应用。膜污染导致渗透通量随时间降低，过滤效率低，过滤成本高。******涂料生产企业的废水中含有多种物质，如：有机/无机颜料、乳胶、溶剂和乳化剂。超滤处理乳胶漆废水会产生污垢，导致水阻力明显增大，渗透通量下降，跨膜压力（TMP）升高。通过我们之前的研究，我们已经建立了机制模型来预测均匀和非均匀孔径膜的膜污染、TMP和功耗。我们还开发了创新的污染修复技术，能够控制乳胶废水交叉流超滤中的膜污染。为了在中试规模和工业应用中进一步发展节能，仍然需要对以下机制有深刻的理解：1)颗粒在孔隙表面的保留（孔隙收缩）；Ii)附着在膜表面，部分或完全阻塞孔入口（形成饼状）；Iii)颗粒聚集导致饼团堆积；颗粒从滤饼层破碎并重新进入截留层的行为及其对结垢的影响。******本研究的目的是使用计算流体动力学和离散元方法（CFD-DEM）来模拟板框膜上的颗粒沉积，包括孔内和表面，与膜污染现象有关。计算粒子到最终捕获位置的轨迹涉及流体动力学和表面相互作用。DEM将与CFD相结合，研究膜污染过程中发生的流体-颗粒相互作用系统，其中溶质（固体）和溶液（流体）相都有助于流动动力学和颗粒沉积。深入了解这一现象，并通过本研究计划开发新颖的创新技术来减少膜污染，对行业具有重要意义。******从拟议的研究计划中产生的主要好处是开发了一种设计分离/过滤膜的创新技术/方法。这种新方法将结合我们的机械污垢附着模型和CFD-DEM模型来实现。开发的方法将对加拿大膜制造商和膜用户产生重大影响。为加拿大工业界培训HQP是拟议研究计划的一个额外好处

Membrane filtration, such as ultrafiltration (UF), is an efficient and energy saving process that has been widely used in water purification, wastewater treatment, biotechnology, and oil-in-water emulsion separation. However, membrane fouling by the solutes/particles in a feed solution is a major challenge for the industry and has operational concerns that are currently hindering widespread application of membrane filtration. Membrane fouling causes a reduction of the permeating flux with time, resulting low filtration efficiency and higher filtration cost.******Wastewater from paint manufacturers contains variety of substances, such as: organic/inorganic pigments, latex, solvents and emulsifying agents. Treatment of latex-paint wastewater with UF results in fouling, which causes a significant increase in hydraulic resistance, permeate flux decline and transmembrane pressure (TMP) increase. Through our previous studies, we have developed mechanistic models to predict membrane fouling, TMP, and power consumption using uniform and non-uniform pore size membranes. We also have developed innovative fouling remediation techniques capable of controlling membrane fouling in the cross-flow UF of latex effluent. For further development towards energy saving in pilot scale and industrial applications, there remains a need for a profound understanding of the following mechanisms: i) particle retention on the pore surface (pore constriction); ii) attachment on the membrane surface causing in blocking of the pore inlet, partially or completely (cake formation); iii) particle aggregation causing cake buildup; and iv) particle break-up behavior from the cake layers and reentering into retenate, and their effects on fouling.******The objective of the proposed research is to use Computational Fluid Dynamics and Discrete Element Method (CFD-DEM) to model the particle deposition on the plate-and-frame membrane, both inside the pore and on the surface, in relation to membrane fouling phenomena. Computing the trajectory of a particle to its final capture location involves both hydrodynamic and surface interactions. DEM will be coupled with CFD to study fluid-particle interaction systems occurring during membrane fouling in which both the solute (solid) and solution (fluid) phases contribute to the flow dynamics and particle deposition. A thorough understanding of this phenomenon and development of novel and innovative techniques to reduce membrane fouling through this research plan are of great importance to the industry.******Main benefit arising from the proposed research plan is development of an innovative technique/method in designing separation/filtration membranes. This novel method will be achieved by combining our mechanistic fouling attachment model and the CFD-DEM model. The developed method will have a major impact on Canadian membrane manufacturers and membrane users. Training of HQP for the Canadian industry is an added benefit of the proposed research plan.**