Waste water, coming from production process, is collected into a pit. Submersible pump (1) placed inside the pit sends the waste water, through the central pipe, deep inside the clarifier (3). Flocculent solution, prepared with a dosing station (2), is injected in this phase, beginning the separation process of the mud from the water. Clarified water rises up and overflow from the top of the silo, being collected into a storage tank (4), ready to be used again in the production process thank to a booster pump group (5); for central spindles of CNC machines a further CNC filter (8) is required. The mud, thickened on the bottom of the clarifier, is discharged into the filter-press homogenizer tank (6). The filter-press (7) dehydrates and compresses the mud until it obtains completely dry panels, ready to be disposed.