Abstract: An oil separation method and apparatus for separation by coarse particulation which includes the steps of forming a coarse particulating element with an oil water separation layer which includes forming a water insoluble hydrogel which has an oil resisting and oil repelling function as well as water permeating and absorbing function on the surface of a porous material and/or the surface of a fluid passage to be contacted with oil holding water and alternately passing the oil holding water through the surface of the element to perform coarse particulation separation of oil at the surface of the element.

Abstract: A method of recycling and purifying water-soluble cutting agents is disclosed. The used water-soluble cutting agent is recycled by filtering through an oil-water separating filter consisting of a porous sheet and an oil-water separating layer composed essentially of a water-insoluble and water absorbable gel layer, which is formed on a surface portion of the porous sheet and is adapted to be contacted with the cutting agent and/or surface portions of the porous sheet serving as flow path.