Mechanism of filter fouling in coagulation-membrane water treatment process

水处理过程的主要目标是从水中分离杂质，即固/液分离。杂质通常以颗粒聚集体(絮体)的形式存在。成功地去除水中的絮凝物减少了消毒剂及其致癌副产品的剂量。 许多市政当局正在探索用膜过滤等先进工艺取代传统的固液分离工艺。然而，水源往往含有高浓度的化合物(污物)，有效地堵塞了膜过滤器。 这些污染物可以有效地固定在膜过滤前处理过程中形成的絮体上。一旦被吸附到絮凝体上，污物就不能再穿透到膜内；相反，它们会在过滤器的表面形成一个多孔饼。这种滤饼通常可以通过对膜的物理清洗来去除。 本研究拟对膜式滤池堵塞机理进行研究。滤清器堵塞蛋糕的结构将使用光学显微镜和医学上使用的先进方法进行分析。蛋糕渗透率的数学模型将利用分形几何的概念来建立。已安排与位于马尼托巴省的两个膜式水过滤厂对这项研究的实验室结果进行现场验证。 许多供水系统可能不得不考虑膜过滤，以满足饮用水质量的严格规定。污垢是无法避免的，但通过仔细设计过滤前处理工艺是可以控制的。膜污染的控制允许更长的过滤运行时间和更少的水被拒绝，这直接关系到工厂的运营成本。

The main objective of a water treatment process is the separation of impurities from water, that is solid/liquid separation. The impurities are usually in the form of particle aggregates (flocs). The successful removal of flocs from the water reduces the dose of disinfectant and its carcinogenic by-products. Many municipalities are exploring replacing conventional solid/liquid separation processes with advanced processes such as membrane filtration. However, water sources often contain high concentration of compounds (foulants) that effectively clog membrane filters. These foulants can be effectively immobilized on the floc formed in the membrane filtration pre-treatment process. Once adsorbed onto the floc, the foulants can no longer penetrate inside the membrane; rather they form a porous cake on the surface of the filter. This cake can usually be removed by physical cleaning of the membrane. This research proposes to study mechanisms of membrane filters clogging. The structure of the filter clogging cakes will be analyzed using optical microscopes and advanced methods used in medical science. Mathematical models of the cakes permeability will be developed using concepts of fractal geometry. Field verification of the laboratory results of this study has been arranged with the two membrane water filtration plants located in Manitoba. Many water supply systems may have to consider membrane filtration to meet the stringent regulations for potable water quality. Fouling cannot be avoided but it can be controlled with careful design of filtration pre-treatment processes. Control of membrane fouling allows for longer filtration runs and for less water to be rejected, which is directly related to the operating cost of the plant.