This system is similar to a conventional decanter but the addition of lamellae multiplies the decantation area and therefore increases the effectiveness. It is a rectangular tank made of stainless steel, GRP or PP, open at the top. Inside there are packages of hollow plastic lamellae with an inclination of 60 degrees. The spill is introduced through an inlet chamber that allows the flow to be directed in a uniform way towards the lamellae. The water rises through the lamellar ducts while the solids are depositing and sliding down the lamellae towards the bottom, where they are collected. The clarified water reaches the surface and is collected by a landfill.