Abstract: A method and apparatuses are presented for rejuvenating a bed of granular filter medium that has accumulated contaminants during filtration of a liquid stream. The method first includes the step of establishing a small volumetric flow rate of clean filtrate in reverse flow. Then, the filter media is agitated to break-up contaminants that have become agglomerated on the surface of or within the interstitial spaces of the filter media. The agitating step is accomplished by exposing the liquid-full filter media to a jetting stream comprised mostly of a gas mixed with a clean liquid. The jetting stream is dispersed throughout the filter media through a plurality of radial nozzles located within the filter bed. The radial nozzles disperse the gas within the liquid and filter media causing sufficient turbulence and agitation of the filter media granules to liberate the trapped contaminants without the need for high liquid flow rates.

Abstract: A gas flotation separator for use in horizontal tanks, such as those used for oil storage on board Floating Production Storage and Off-loading (FPSO) vessels, includes dividing the tank into a plurality of chambers operating in series. Prior to entering each chamber, the contaminated aqueous phase is mixed with a stream containing gas bubbles to aid in flocculation and flotation of the immiscible phase contaminant. The gas bubble recycle stream can be generated by injecting a controlled rate of a pressurized gas into a liquid stream of the clean produced water in a process external to the tank or by induction of a gas phase internal to the tank. The mixture flows into the first chamber and impinges on an angled inlet water weir. A portion of the immiscible phase and the gas phase rises to the top of the chamber while the remaining immiscible contaminants flow downward with the aqueous phase to the bottom of the chamber.