Filter presses are intended for the mechanical dewatering of wastewater sludge, as well as of the water conditioning sludge, and of the industrial slimes. Belt filter presses are used extensively at the wastewater treatment plants due to its high productivity and reliability.
For sludge with an initial moisture of more than 97.5%, the capacity can be increased by the use of “Comby” filter presses (with thickener). Such decisions increase productivity with initial sludge due to the lengthening of the gravity dewatering zone.
Dewatered sludge reaches residual moisture of about 75-80% after the filter press, at an average polymer dose of 2-3,5 kg/t of the sludge dry matter.
The filter presses are manufactured from stainless steel AISI 304 and only their high-loaded shafts are manufactured from carbon steel covered by solid polymer. The filter presses operate as a part of the mechanical dewatering system. The standard system may include the thickener, initial sludge- and flocculent solution dosing pump, the station of flocculent solution preparation, compressor and transporter for dewatered sludge.
Structurally, the belt filter press features a system of rollers installed on the frame between which the two endless belts are stretched and connected into endless ducts. Two belt flushing assemblies, sludge feeder and distributor and the filter cake removal device are provided with the filter press.
All movable parts have a high wear resistance and protection. All parts in contact with sludge on stream are protected against any corrosive medium.
Sludge dewatering installation in the “Comby” version features the belt filter press PL series and belt thickener SG mounted on it.
The filter press operates in continuous mode. The sludge mixed with flocculent is supplied to the moving top belt and distributed all over its operating length. Throughout the movement, the sludge layer is constantly mixed by a ripper system for improved water outflow.
Water draining in this zone (gravity dewatering zone 1) occurs by gravity feed. Roughly 50% of the water contained in the sludge (filtrate) is drained during this stage. The sludge then enters a wedge-shaped preliminary pressing zone where the belts converge and mechanical pressing starts. To prevent sludge splashing and extruding along the belt edges, the pressure on the sludge increases gradually. In the preliminary pressing zone, the filtrate is separated more intensively. The first rolls are manufactured from stainless steel and are perforated. This allows water drainage through both filter belts as the external and the internal surfaces make contact with the roll.
The maximum pressure on the filter cake (formed in the preliminary pressing zone) takes place on 6 rollers of which the diameter decreases along the direction of the belts. Owing to the special geometry of the rolls' location, the surface pressure, which is directed along the roll radius and tangent, affect the filter cake.
The dewatered sludge is then removed from the belts by special polymeric scrapers into a receiving bin. After the filter cake removal, the belts are flushed in the regeneration zone. Dewatered sludge can reach a residual moisture of 75-80% after filter press, at flocculent average dose 2-3.5 kg/t dry sludge matter.
In the “Comby” version, the initial sludge after the polymer treatment is fed into the top of the unit on the belt thickener, where preliminary sludge dewatering under gravity is done. After the, thickener the sludge is supplied into the filter press gravity dewatering zone.
The filter presses are provided with drives, belt position-, speed- and tension control system sensors and an air pressure loss protection system. It allows complete automation of the dewatering units on the basis of filter presses to implement.
All electric sensors and drives have a high level of protection against moisture and ambient air corrosive action.
An indication system of normal operation and emergency situations is provided.
It is possible to transfer equipment status data to a higher level automated process control system depending on the client’s requirements.
|Capacity by dry matter, up to, kg/h||200...1100|
|Capacity by initial sludge, up to, m3/h||5...50|
|Belt, width, mm||600...2000|
|Belt's speed, m/min||2...10|
|Drive power, kW||0,75...3,3|
|Weight, not more than, kg||2990....660|