Abstract: A process and apparatus for the chemical-mechanical treatment and purification of ground and surface waters and effluents of various types employs adding materials for coagulation, flocculation, precipitation, sedimentation and altering the pH value. The process comprises separate process stages carried out successively as follows: (1) a first initial process stage wherein certain additives are admixed to the raw water by stirring; (2) a second initial process stage wherein contact sludge is admixed by stirring; (3) a third initial process stage wherein a flocculent aid and possibly also at least some of the other materials added in the first stage are admixed by stirring with high energy input; and alternatively (4) a fourth initial process stage for the formation of course flocs and completion of reaction of the previously added materials and formation of settleable particles and conglomerations of particles together with adsorbed and attached and occluded raw water components with moderate movement.

Abstract: Liquid to be treated flows into a combined sedimentation and thickening tank. The upper part of this tank is a sedimentation zone in which the liquid passes through parallel flow paths between downwardly inclined separator plates below which the solids fall to the bottom of the tank into the thickening zone whereat the solids are stirred and removed by a suitable stirring and scraping device. The liquids flowing with the solids through the parallel paths are removed at the end of said paths and delivered directly to the top of the sedimentation zone thus leaving the thickening zone essentially flow-free. Flocculants may be added to the water to be treated in a separate flocculation compartment arranged upstream from the sedimentation compartment. A separate destabilization compartment may be provided upstream from the flocculation compartment. A square sedimentation zone may merge smoothly into a circular thickening zone. The thickening zone may extend beneath the flocculation compartment for compactness.

Abstract: Liquid to be treated flows into a combined sedimentation and thickening tank. The upper part of this tank is a sedimentation zone in which the liquid passes through parallel flow paths between downwardly inclined separator plates below which the solids fall to the bottom of the tank into the thickening zone whereat the solids are stirred and removed by a suitable stirring and scraping device. The liquids flowing with the solids through the parallel paths are removed at the end of said paths and delivered directly to the top of the sedimentation zone thus leaving the thickening zone essentially flow-free. Flocculants may be added to the water to be treated in a separate flocculation compartment arranged upstream from the sedimentation compartment. A separate destabilization compartment may be provided upstream from the flocculation compartment. A square sedimentation zone may merge smoothly into a circular thickening zone. The thickening zone may extend beneath the flocculation compartment for compactness.