Stepwise membrane fouling model for shear-enhanced filtration of alfalfa juice: experimental and modeling studies

Alfalfa juice is predominantly created from the production of fodder pellets for cattle. Due to its high nutritive value and abundant sources, an inappropriate treatment may cause important environmental problems. Membranes are used to separate and concentrate leaf protein from alfalfa juice. However, membrane fouling reduces process efficiency and hinders wide application. This study investigated the fouling of MF and UF membranes by foulants of alfalfa juice. Permeate flux gradually increased with TMP in a stepwise pattern. A stepwise multisite Darcy's law model (SMDM) was proposed to simulate the stepwise multisite fouling process. Besides, the resistance coefficient and compressibility for different steps and sites were calculated to explain the complex fouling process. The effects of feed composition, membrane and hydraulic conditions on the stepwise fouling process were investigated. These various factors have a strong effect on the fouling process of industrial membranes. A series of long term tests were utilized to study flux decline and membrane fouling at various steps and sites of the fouling process. The results of this investigation can help us to understand the fouling process of alfalfa juice and facilitate membrane fouling control.