Water treatment method by ballasted floc including a recycling of granular material

• Main Authors: PATRICK BINOT, GENEVIEVE BOISSONNADE, PASCAL MOREAU
• Format: Patent
• Language: English
• Published: 05.06.2000
• Edition: 7
• Subjects: APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES; CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL ORCHEMICAL PROCESSES; CHEMISTRY; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLIDMATERIALS OR FLUIDS; METALLURGY; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATICTABLES OR JIGS; SEPARATION; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS; SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATICTABLES OR JIGS; TRANSPORTING; TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE

The invention concerns a flocculation-decantation method by ballasted flocs using a granular material and a step which consists in treating the sludge derived from flocculation-decantation in a circular grit trap wherein the auxiliary liquids tangentially injected into the sludge substantially in the same direction as the latter. The invention also concerns a circular grit trap with a cylindrical part of diameter D tangentially supplied with the suspension to be treated and a conical part and provided with a cylindrical chamber injecting wash-water provided at the conical part outlet and having a diameter D' ranging between 0.35 D and 0.65 D, said cylindrical chamber having at least a tangential supply of auxiliary liquid along the same feeding direction as said tangential supply of the suspension to be treated.