Patent ID: 7445708

Claim:
A unit for purifying water contaminated by droplets of hydrocarbonaceous liquid and other pollutants, comprising: an essentially vertically positioned filter; an inlet chamber for said contaminated water partially defined by a first vertical surface of said filter; an outlet chamber for filtrated water partially defined by a second surface of said filter opposite to said first surface relative to the filter; supply means for contaminated water debouching in a lower portion of said inlet chamber; outlet means connected to an upper portion of said inlet chamber for discharging hydrocarbonaceous liquid separated from the water in said inlet chamber; duct means for recovering purified water from said outlet chamber; and means for injecting gas as fine bubbles into the contaminated water in at least one location selected from locations in the lower portion of said inlet chamber and locations in said supply means, the means for injecting gas producing a stream of gas bubbles upwards along said first vertical filter surface to release and remove upwards droplets of hydrocarbonaceous liquid and vapour bubbles settled on the filter surface and to entrain and remove upwards such droplets and vapour bubbles otherwise prone to settle on the filter surface, thereby delaying blocking of the filter surface and promoting a merging of said droplets to form a continuous hydrocarbonaceous phase in said upper portion of the inlet chamber.