Method of treating water by ballasted flocculation/settling, which includes a continuous measurement of the ballast, and corresponding installation

A method for treating water in a ballasted flocculation system comprises directing water into a ballasted flocculation zone and adding ballast and a flocculation reagent to the water to form a water-floc mixture. The water-floc mixture is directed into a settling zone to form treated water and sludge containing ballast. The ballast is then directed to a recirculation line where the ballast is recirculated to the ballasted flocculation zone. The method further includes determining the ballast concentration and comparing the ballast concentration with a predetermined threshold value. The rate at which ballast is recirculated to the ballasted flocculation zone is adjusted based on the determined ballast concentration and the predetermined threshold value. A ballasted flocculation system for treating water comprises a ballasted flocculation zone, a water inlet for directing water into the ballasted flocculation zone, and a flocculation reagent inlet for directing flocculation reagent into the ballasted flocculati