Method of plain sedimentation and physical-chemical sedimentation of domestic or industrial waste water

摘要

An untreated flow of waste water is normally introduced into a plain sedimentation unit during plain sedimentation periods to separate it into sand and a flow treated by plain sedimentation. During other periods, for example periods of heavy rain, a coagulating agent, ballast sand and a flocculating agent are introduced. The coagulated flow is passed into a maturation intermediate area and then, with substantially all the sand and colloids of particles attached to it, into the plain sedimentation unit. Here effluent is separated by plain sedimentation and evacuated and sludge made up of the sand and the adhering colloids and particles is extracted and evacuated via an extraction system and the sand outlet channel of the plain sedimentation unit. The sludge is collected, the ballast sand is separated from it to be recycled into the sand injection area and the sludge and excess sand are extracted.