With the Filter Press we get to dehydrate the sludge, even reaching dryness of 35-40%. Taking into account that in a WWTP, the costs of sludge management, account for almost 70% of the total expenditure, it is important to have an equipment that achieves the maximum degree of dryness of the sludge, with consequent savings in the cost of management.
With the filter press you get:
– Low energy consumption.
– Great dryness of the sludge.
– Large filtering surface in a small space.
– Ease maintenance.
– Fully automated.
Stages of the Filtering Cicle
1. CLOSURE OF FILTER PRESS. The initial phase of the filtering cycle starts with the closure of filter press. Movable plate is triggered by hydraulic system and is moved closing the filter at the pressure needed for the work, which is controlled with a pressure switch positioned in hydraulic circuit.
2. FILLING. Starts the sludge pumping to filter press. Chambers are filled with sludge and starts the formation of cakes. Solid particles are retained on the cloth’s surface, while the liquid crosses them and flows out through the draining system of filtering plates. Initial filtering pressure is minimal and raises as the number of retained particles increases.
3. FILTRATION. Maximum filtering pressure is reached and maintained until the sludge pump stops. An appropriate dewatering level for cakes is reached during the initial draining time. Then, the compressed-air valve is opened to clean the central channel and remove the remaining sludge.
4. OPENING OF FILTER PRESS AND CAKES DISCHARGE. After final draining the filtering unit is opened. Shaped cakes now drop as plates are separating. Once the filter is completely opened, the shaker starts to run and it helps to the total discharge of cakes.
Table 1.- Characteristics of different mechanical dehydration technologies