Abstract: A system for filtering fluids uses the pressure differential across a filter element between an internal filter volume and an external filter volume to control the rate of fluid flow through the filter element. The internal filter volume communicates with a backwash volume contained in the external filter volume. The backwash volume may be movable relative to the filter element to clean accumulated filtrate from the filter element through backwashing. By increasing the pressure in the internal filter volume, the rate of backwashing can be increased while the rate of fluid flow into the internal filter volume is decreased. Particularly when the filter element becomes clogged, damage to a filter caused by an excessive pressure differential across the filter element may be decreased.

Abstract: Dispersions of oil and similar liquids in water are clarified with separation of the oil and water phases by mixing the dispersion with a polymer dissolved in an oil miscible solvent in a manner such that contact between the polymer solution and dispersed oil droplets is achieved. The polymer must be soluble in the oil and must have a molecular weight sufficiently high to impart viscoelasticity to the resulting solution of polymer in solvent and oil. Thereafter, the oil and water phases are readily separated by settling and decantation, or by enhanced phase separation techniques such as centrifugation.