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Literature Review & Summary Report Design Basis Memorandum

BCI Project No. 19-15089 September 2007

St. Johns River Water Management District Contract # SK940AA

Page 15

flocculated solids. The dewatered belt press cake is scraped off the belts and drops into a containment pan.

Generally, a belt filter press receives pre-thickened sludge ranging from a very low 4 % to a more typical 15 % solids and produces a final product of 12 - 35 % cake solids; performance depending on the nature of the solids being processed. Filtration rates for the largest units are approximately 450 gallons per minute treating about 15 tons of solids per hour.

Figure 10 Belt Filter Press

2.4.3 Equipment Type- Plate and Frame Press

A plate and frame press (Figure 11) consists of a series of frame supported plates that contain facing recessed sections. This forms a void into which liquid sludge can be transferred for dewatering. The plates that form the recessed chambers are filter media lined to retain sludge solids while discharging filtrate. During the filtration cycle, sludge is pumped under pressure into the volume formed between the plates. As the filtration process progresses, filtrate passes through the solid cake and filter media. This process continues until a maximum pressure or minimum flow rate is achieved. This maximum design pressure is then maintained until the desired cake solids content is achieved. The filtration cycle is ended when a practical low feed rate is achieved. The sludge feed pumping is stopped, the individual plates are separated, and the sludge cake is discharged.

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