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 lamellar pack in PP with padding of 44x44 mm and internal septa to determine the various compartments of separation and structure reinforcement, which will also ensure walkability class A15, tubes and profiles made ​​of similar material (PP HD). Said units are accompanied by inspection manhole and withdrawal floating materials, sand and aggregates and inlet and outlet holes suitably dimensioned and equipped with suitable gaskets rubber lip.