Abstract: To improve the dewaterability of sludge, which is dewatered in a dewatering device, in particular a plate filter press, a polymeric filter aid is added to the sludge. Since the flocs require a certain ripening time to form, a part stream of the unfiltered sludge is to be taken off according to the invention at the point opposite the feed and recycled into the main stream. The recycled flocs serve as flocculation nuclei. A further advantage of the sludge recycle is that the floc structure and/or size can then be scanned in the recycled part stream. The representative measured results are utilized for changing parameters which determine the dewaterability.

Abstract: The invention relates to filter plates of plate filter presses, particularly for freeing sewage sludge from water.The problem of premature failure of the filter cloth is overcome in that the filter cloth is fastened only at some of the support bosses surrounding the central inlet opening and is laid loose over the other bosses. Excessive bulging of the filter cloth when the cake is thrown off is thereby avoided. The filter cloth may be held by a subsequently fastened boss or by a cap engaging over the boss.

Abstract: In order to enlarge the size of the filter plates of a plate filter press without prejudicing the handling of the filter plates, an additional filter plate is arranged beneath each filter plate and is connected to this uppermost filter plate by members, such as by articulated connecting elements. Suspension and guide means are provided only for the uppermost filter plates.

Abstract: A filter press with filter plates slidable individually by a transport element has on each filter plate a locking hook which cooperates for locking with a locking bolt of the adjacent filter plate. A pivotable blocking element, which in the blocked position, positively blocks the locking hook locking this filter plate against unlocking and is connected to an actuating member which projects into the path of the transport element so that immediately before the latter takes along the relevant filter plate it engages the actuating member and thus pivots the blocking element into a release position so that the filter plate is separable after release of the locking hook. Each respective filter plate to be slid thus remains positively locked to the as yet unopened plate stack until immediately before it is taken along by the transport element and cannot become separated from the stack accidentally.

Abstract: To equalize the precoat application over the length of the filter press and/or over the height of each filter cloth, the drainage of at least a part of the carrier medium occurs at at least one, and preferably at a plurality of regularly distributed, drainage points located between the ends of the filter press, and preferably at a throttled rate, so that a pressure is built up in the filter chambers. At least one filter plate, and preferably a plurality of filter plates arranged at regular intervals, is provided with additional drainage orifices for the carrier medium at the upper end thereof with such additional drainage orifices being connected by flexible hoses to one or more filtrate-collecting pipes. The total cross-sectional area of all of these additional drainage orifices is smaller than the total cross-sectional area of the filtrate drainage channels used during filtration.

Abstract: A plate-type filter press having a cleaning truck movable in the direction of movement of the slidable filter plates embodies a drive and a pusher adapted to be brought into engagement with the filter plates. The cleaning truck has a releasable brake and the pusher is extensible by the drive in the direction of movement of the filter plates.

Abstract: A sludge de-watering plant has a plurality of filter presses connected in parallel with at least two low-pressure pumps delivering a high rate of sludge for rapid filling of the presses and at least two high-pressure pumps substantially effecting the filtration. A particular pipe system is associated with each of the low-pressure and high-pressure pumps with the pipe systems being connected to the individual filter presses for mutually independent delivery. Control means mutually controls the pumps in the two pipe systems independently by the relevant pressure in the pipe systems.

Abstract: A process and apparatus for the batch-wise filtering of a sludge-like material in which the discharge period of the filter press is used for filling a pressure vessel containing air with a pump being also used during this period. During the filtration period the pump can operate solely for feeding the filter press to thereby increase the filtration capacity and reduce the required filtration period. During the discharge period the pump also operates exclusively for feeding the pressure vessel to further speed up the process. The pump can operate continuously and the different steps of the process can be controlled by only opening and closing control valves.

Abstract: A chamber filter press embodying movable filter plates suspended for movement along horizontal guides by an endless transporting assembly driven by a reversible motor and carrying dogging members which cooperate with cams on the filter plates as the press is opened. A switch connected to a time control device reverses the motor when the filter plate which has just been moved rests against the previously moved filter plate and at the end of a preset time the time control device switches the motor from reverse to forward motion. The motor is stopped by a limit switch which is operated by a dogging member at the end of a preset time after the last filter plate has been moved forward.

Abstract: Apparatus for conveying and dewatering wet coarse screenings debris comprises a drag chain conveyor having a conveying flight. A pressing unit is mounted above the conveying flight and exerts a downward pressure on the debris. A trough having a perforated bottom is mounted beneath the conveying flight in the vicinity of the pressing unit.

Abstract: A transport device for displacement of filter plates embodying a transport pawl pivotally mounted on a drawing element disposed to move the plates in the direction of opening. The pawl has a recess which cooperates with upwardly extending catches and a forward deflector surface which cooperates with the catch of an adjacent plate in a stack of plates to prevent the pawl from dropping into operative position. At least one additional pawl is pivotally mounted on the drawing element and has an additional deflector surface rearwardly of the recess therein which cooperates with the catch of an adjacent plate. The recess in the pawl may be of a length to engage two catches carried by two adjacent plates.

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: The upper flight of an endless filter belt is supported by a backing sheet as it passes through a feeding and initial partial dewatering zone. The upper flight of the filter belt then passes through a main dewatering zone while being subjected to pressure in a direction to force liquid therethrough. Drainage slots in the upper surface of the backing sheet extend at an angle to the direction of travel of the upper flight and leave narrow strips between adjacent slots which engage the under surface of the upper flight.