Cross flow filter apparatus

A cross flow filter apparatus and method uses an open tank having a first liquid retaining section, a second filter retaining section and a third solids collecting section in fluid communication with each other. A filter assembly is retained within the second section and includes a filter panel having a generally vertically disposed filter membrane surface, preferably with submicron pores. Filtrate is removed by applying low vacuum pressure, in the range of about 5 inches vacuum pressure (Mercury), in communication with the filter panel such that filtrate is drawn through the pores of the filter membrane surface at a flow rate Qout. Fluid to be filtered is cross flowing vertically downward across the filter membrane surface at a flow rate Qx, such that the horizontal velocity Vh of fluid drawn through the filter membrane surface is less than the vertical velocity Vv of the cross flowing unfiltered fluid. The excess high velocity cross flowing unfiltered fluid imparts a shearing action to particles resting on the filter membrane surface to rehabilitate the filter membrane, thereby continuously offering a clean filter membrane surface for continued filtration. Excess unfiltered cross flowing fluid is recirculated between the first and second sections of the tank, while allowing entrained particles to settle to the solids collecting section of the tank as the recirculated fluid mixes with incoming unfiltered fluid prior to recirculation and discharge vertically downward across the filter membrane surfaces.