Grit removal and oil removal unit consists of a block made in sheets of PP-HD thermowelded with continuous wire of the same material, complete with internal septa which determine the various compartments of separation and reinforcement structure, capable of ensuring the pedestrianization class A15, pipes and profiles made ​​of similar material. These units consist of two or more branches of which, the first "catch" the oil sands and aggregates at the top and bottom number, the second and any other compartments allow the further separation of any oil sands and waste, as well as the 'output of treated wastewater. Are also accompanied by manhole covers for the inspection and removal of the oils and of the sands and inert precipitates prepared in the compartment, and inlet and outlet pipes suitably dimensioned.