The mixture of solids and water that flows in the rigid horizon-tal pipe and the return flexible pipe is then passed through a sep-arator consisting of a closed box fitted with a side hatch and whose bottom side consists of a grid of stainless steel. The water then falls into the tank 2, and the solids flow in a chute that is inclined at 45. This chute provides at its end an adjustable flap in order to control the solids flow rate. The end of the chute is above a grid container of known capacity that is immerged in tank 1 and connected with a grid pipe to the outlet of tank 1. The separated water flows from
tank 2 into tank 1 through a pipe with an electromagnetic flow-meter. The mixture is sucked by a vortex pump (Ensival Moret MT 100-100-250) connected to the outlet of tank 1 and delivered in the circuit.