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Literature Review & Summary Report Design Basis Memorandum St. Johns River Water Management District Contract # SK940AA

BCI Project No. 19-15089 September 2007 Page 29

Disadvantages:

The belt filter press cake is not as “dry” as filter press cake; therefore, waste volume reduction is somewhat less than other technologies.

The belt filter press functions as a secondary dewatering step, necessitating a pre- thickening step; usually accomplished by a conventional thickener or clarifier. This technology must be considered a step in a more complex process and is not applicable as a stand-alone dewatering system. Additionally, return water will likely need treatment to remove dissolved phosphates prior to reintroduction to the lake.

4.4.3

Plate and Frame Press

Advantages:

Due to the nature of the plate and frame press, sludges typically difficult to dewater respond well and reach solids as high as 30% by weight. In some applications, the plate and frame press has a very high solids capture rate and is one of the few mechanical devices capable of producing a cake dry enough to meet landfill requirements in some locations.

As with most mechanical dewatering systems, the need for settling basins, return water systems, and containment area restoration, as well as the piping and pumps to the settling area is eliminated.

Disadvantages:

Plate and frame presses have a high capital cost, especially for variable-volume filter presses. Large quantities of conditioning chemicals are commonly used, and if the sludge is poorly conditioned or if the press is not automated, labor cost may be high as well.

Additional disadvantages include replacement filter media that is both expensive and time consuming, and noise levels caused by feed pumps can be excessive. Batch discharge after each cycle also requires consideration of receiving and storage.

The plate and frame press functions as a secondary dewatering step, necessitating a pre- thickening step; usually accomplished by a conventional thickener or clarifier. This technology must be considered a step in a more complex process and is not applicable as a stand-alone dewatering system. Additionally, return water will likely need treatment to remove dissolved phosphates prior to reintroduction to the lake.

4.4.4

Bucher Hydraulic Press

Advantages:

The Bucher hydraulic press is fitted with a strong, hard wearing filter cloth (similar to recessed-plate filter cloth) which holds back the sludge solids. The Bucher HP hydraulic press

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