METHOD OF TREATING A SUSPENSION HAVING A LOW CONCENTRATION OF SUSPENDED MATERIAL

In a method of treating a suspension contained in a reservoir (8), the suspension is flowed through a tube (1) which has an inlet end (1a) and an outlet end (1b) and the interior of which communicates, via a perforated portion (1c), with a closed chamber (2) having an outlet (4). The tube (1) and the chamber (2) are immersed in the suspension, the outlet end (1b) of the tube (1) being connected to an outlet pipe (13), its inlet end (1a) being exposed to the suspension, and the outlet (4) of the chamber (2) being connected to an outlet pipe (15). The suspension is continuously pumped through the tube (1) by a first pump (14) to form, close to the tube wall, a laminar boundary layer in which the concentration of suspended material is lower than in the rest of the suspension and which is drawn off into the chamber (2) through the perforated portion (1c). The suspension having a lower concentration of suspended material is pumped out of the chamber (2) by a second pump (16) connected to the outlet pipe (15) of the chamber. A lower pressure is maintained in the chamber than in the tube (1).