Optimisation of a back-flush sequence for zeolite microfiltration

Cross-flow microfiltration experiments were performed on a zeolite suspensi on through a 0.45 mu m pore size ceramic membrane. A back-flush device was designed in order to remove fouling deposits periodically from the membrane surface. This device allows a direct measurement of the amount of permeate back-flushed into the system and this feature enables a better understandi ng of the cake removal. The optimal back-flush conditions minimising the am ount of permeate back-flushed and ensuring a complete removal of the cake w ere 0.2 s back-hushing time at a back pressure of 2 bar. The optimal forwar d filtration time between flushing depends on the suspension concentration. This technique gave more than a 100% improvement in some cases, and a gene ral model based on a dead-end filtration process was developed and gave ver y consistent results. The cake deposit on the membrane surface was also stu died and compared to a deposit in a dead-end process. (C) 2000 Elsevier Sci ence B.V. All rights reserved.