METHOD FOR TREATING WATER BY BALLASTED FLOCCULATION AND DECANTATION

• Main Authors: ZUBACK, JOE, DAHL, CLAUS, POULSEN, BINOT, PATRICK
• Format: Patent
• Language: English; French; German
• Published: 19.10.2005
• Edition: 7
• Subjects: APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES; CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL ORCHEMICAL PROCESSES; CHEMISTRY; METALLURGY; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; SEPARATION; TRANSPORTING; TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE

The procedure for treating water containing colloidal, dissolved or suspended impurities, pre-coagulated in advance, consists of passing the water through a flocculation zone (3) containing an insoluble ballast such as sand, followed by a decantation zone (4) in which the treated water is poured off the sludge and ballast mixture. The procedure for treating water containing colloidal, dissolved or suspended impurities, pre-coagulated in advance, consists of passing the water through a flocculation zone (3) containing an insoluble ballast such as sand, followed by a decantation zone (4) in which the treated water is poured off the sludge and ballast mixture. The mixture is fed to a separator (7), from which over 20 per cent of the volume entering it is recycled to or upstream of the flocculation zone. The ballast (sand) has an actual density greater than 2, and the separator has one or more cyclones that recover 99.5 per cent of the ballast and 40 per cent of the sludge. A variant of the system uses a simple gravity decanter under pressure and a hydrocyclone to separate the sludge and ballast mixture, and activated carbon in powder form can be injected into or upstream of the flocculation zone.