Mechanism of filter fouling in coagulation-membrane water treatment process

点击翻译按钮获取中文摘要

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.