Instalación para el tratamiento del agua por floculación lastrada y decantación integradas, y procedimiento correspondiente

The invention relates to a water treatment plant comprising: means for supplying water for treatment, wherein said water has been coagulated previously, a flocculation-decantation device having means for dispensing at least one flocculant reagent, means for dispensing at least one ballast, means for extracting decantation sludge, means for discharging the treated water, means for separating said ballast contained in the ballasted sludge, and means for recycling the ballast that has been cleaned in this manner back into the flocculation-decantation device, characterised in that: said flocculation-decantation device has a single tank in the lower portion of which a stirring mechanism is arranged; wherein said single tank comprises slats in its upper portion; and said slats are separated from the stirring mechanism by a distance "d" which is between approximately 0.5 metres and approximately 3 metres. The invention also relates to a method using said plant.