The tank (1) has a bottom (2) surmounted by two side walls (3), where upper end of one of the side walls includes an attachment unit (5) on a support. A waste-prevention frame (7) and the attachment unit are inclined at an angle relative to a vertical, where the angle of inclination of the waste-prevention frame relative to the vertical is preferably between 45 and 75 degrees. The attachment unit includes a horizontal surface (6) and a slope having an inclination angle preferably between 45 and 75 degrees relative to a plane of the horizontal surface.
