The proposed project comes from the need of the company Sicula Trasporti s.r.l. to increase the treatment capacity of the ever-growing amount of undersieve waste produced by mechanical selection of mixed waste. In particular, the enlargement of the existing plant consists of a new section of aerobic biostabilization of undersieve originated from mixed waste treatment plants. In this section, the aerobic biostabilization will occur through dynamic windrows subjected to forced ventilation, inside two closed concrete sheds. These sheds will be kept in aspiration with no. 3 hourly air changes; exhaust air will be conveniently treated. The project provides an increase of the aerobic biostabilization treatment of non-hazardous waste amount equal to 150.000 t/year. This new capacity, together with the existing authorized one which is 315.000 t/year, increases the plant capacity up to 465.000 t/year (operation D8 according to Encl. B and C referring to Part IV of Law Decree No. 152/06 (D.Lgs. 152/06) and further amendments.