A regeneration method for a filtration apparatus, a filtration apparatus, and a water treatment apparatus are disclosed that shorten a time required until stabilization of water quality of filtrate after backwashing, and stably provide filtrate satisfying a desired water quality standard. The regeneration method for a filtration apparatus according to the invention is a regeneration method for a filtration apparatus that has a filter layer formed by filling a solid filter material formed with a protrusion on a surface, and passes water to be treated containing suspended matters through the filter layer to perform filtration of the suspended matters. The regeneration method for a filtration apparatus includes a step of backwashing the filter layer by passing washing liquid through the filter layer in a direction opposite to a passing direction of the water to be treated such that the protrusion is retained on the surface of the solid filter material.

A hydrocarbon filtration system is provided for removing a contaminant. The filtration system includes a housing unit; a porous compressible filtration media disposing within the housing unit; and a lower and upper perforated plates in between which the porous compressible filtration media is disposed. At least one of the upper or lower perforated plate is movable relative to the other perforated plate for compressing and decompressing the porous compressible filtration media. A coalescence promoting device is positioned within the housing unit and above the upper perforated plate. The coalescence promoting device is configured to promote the coalescence of a hydrocarbon in the housing unit. Also provided is a method of treating hydrocarbon containing fluid by performing a filtration cycle followed by performing a wash cycle to wash a contaminant from the filtration media. During the wash cycle, an upper segment of the housing unit between an upper wall of the housing unit and the filtration media can be a gas-free zone.