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: A process and apparatus for treating wastewater with oxygen in which the wastewater is circulated on a horizontal course and is exposed to the introduction of oxygen or oxygen-enriched air in one or several sections of its course whereas it is exposed to the atmosphere on the remainder of its course. Oxygen of a higher concentration than atmospheric oxygen is contacted at least intermittently with the water surface and introduced into the wastewater through agitation of the water surface. At least a part of the total volume of the wastewater is treated by carrying out alternately at least two of the following three modes of operation: (a) surface aeration of the wastewater using atmospheric air; (b) oxygenation while maintaining atmospheric pressure above the wastewater; and (c) oxygenation while maintaining positive pressure above the wastewater with the operating modes alternating with each other in response to variations in the volume and/or character of the wastewater being treated.

Abstract: A pump for conveying waste water and the like embodying a substantially vertically arranged drivable screw mounted for rotation within a fixed pipe having an inlet at the lower end thereof and an outlet at the upper end thereof. At least one upstanding baffle is mounted below the screw and in the vicinity of the inlet with at least the upper portion of the baffle extending in the direction of conveyance.

Abstract: A plate-type filter press having filter plates suspended by centrally disposed support means is provided with a flushing unit insertable from below into the space between adjacent filter plates. Guide means are arranged in the proximity of at least one of the upper corners of the filter plates to prevent the plates from swinging relative to the support means and still permit insertion of the flushing unit between adjacent filter plates.

Abstract: Spraying apparatus for cleaning filter press plates which are slidable along horizontal guides. A spray unit is provided with at least one row of spray nozzles located at spaced apart locations thereon and directed at the vertical surface of an adjacent filter plate. The spray unit is reciprocated over a distance equalling the distance across the filter plate to be cleaned whereby spaced apart areas are sprayed by the nozzles of the row of nozzles as the spray unit makes one run relative to the filter plate. Spray nozzles are positioned on the spray unit during the return run thereof between the spaced apart locations of the nozzles of the row of nozzles to spray the areas between the previously sprayed spaced apart areas on the return run of the spray unit. Fluid is supplied under pressure to the row of spray nozzles as the spray unit makes one run and to the spray nozzles located between the spaced apart locations as the spray unit makes its return run.

Abstract: A process and apparatus for operating a filter press having a sludge feed pump and a pressure tank in communication therewith wherein during filtration a quantity of sludge is withdrawn and stored in the pressure tank under a cushion of compressed air and wherein sludge is introduced under pressure from the pressure tank into the press during the next charging operation. A conduit having flow control means therein communicates the upper portion of the pressure tank with the press for injecting compressed air therein. The upper portion of the pressure tank also communicates with a compressed air supply conduit having flow control means therein which is controlled automatically as a function of the sludge level in the pressure tank.

Abstract: A filter plate having a plate frame with filtrate discharge means covered by filter cloth adjacent the bottom of a filter cake chamber defined by recesses in the plate. A cam projects from the bottom of the filter cake chamber and is adapted to support the filter plate on a corresponding cam on an adjacent filter plate with the cam extending substantially to the level of the outer surface of the frame of the filter plate. An opening is provided in the filter cloth covering the plate frame for receiving the cam. A clamping ring surrounds the cam and the filter cloth adjacent thereto to form a seal therebetween. A washer-like member overlies the cam and a portion of the clamping ring and retains the clamping ring in place.

Abstract: An endless traveling band screen formed of a plurality of screening elements is carried by endless, impermeable, flexible drive belts which extend along opposite sides of the traveling band screen adjacent the ends of the screening elements. The belts travel around upper and lower rotary members with sealing means interposed between adjacent screening elements, between the screening elements and the belts, and between the belts and adjacent walls of the screening unit.

Abstract: A cover for manhole structures embodying a metal portion constructed of high strength material and assembled to provide maximum strength with a minimum of weight. A concrete portion is carried by the metal portion with the weight of the concrete portion being so proportioned relative to the weight of the metal portion that the combined weight thereof provides a manhole cover of a predetermined minimum weight.

Abstract: A rotary aerator is mounted for rotation about a horizontal axis and has a plurality of agitator elements formed integrally with hub segments to provide generally star-shaped members which extend radially from the circumference of the aerator along the length thereof for introducing air or other gases into waste water or other fluids.