Patent ID: 7025885

Claim:
A process for filtering water comprising, (a) introducing a feed water containing an initial concentration of solids into an open tank to immerse one or more filtering membranes located in the open tank, the feed water contacting a first side of the membranes; and (b) in repeated cycles, (i) applying suction on a second side of the membranes to withdraw a filtered permeate while adding sufficient feed water to keep the membranes submerged and permitting the concentration of solids in the water in the tank to rise to an increased concentration; and, (ii) partially deconcentrating the tank by (A) draining a volume of water equal to between about 75% to 20% of the volume of the water in the tank at the end of step (i) from the tank and (B) introducing a similar volume of feed water into the tank.