UFC 3-280-03
23 JULY 2003
CHAPTER 3
DESIGN CALCULATIONS
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INTRODUCTION. This chapter describes the general types of calculations
that may be required for filter press applications. Based on the specific type of sludge
being dewatered, sludge dewatering conditions, and the specific type of equipment and
accessories used, additional calculations may be required. Although the calculations
that are described refer primarily to filter presses, several of these calculations depend
on, or should be used in conjunction with, other calculations that should be used in the
development of the design for the entire treatment process or treatment facility. Design
examples illustrating the use of several of these calculations are presented in Chapter
5.
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PURPOSE. Filter press design calculations primarily provide design criteria
for sizing equipment for editing guide specifications and developing construction
drawings. Based on the preliminary selection of equipment, additional calculations can
also determine parameters such as utility requirements and supporting mechanical and
electrical distribution systems.
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DESIGN BASIS AND DATA SOURCES. Several types of data sources can
be used for the basis of the design calculations. Typical sources of data include pre-
engineering design reports and treatability studies, standard reference materials, and
other sources such as telephone conversations. Any source of data or basis used for
the design calculations should be identified and referenced appropriately in the design
analysis.
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Pre-engineering Design and Treatability Studies. Pre-engineering design
reports and treatability studies (i.e., laboratory, bench-scale or pilot scale testing, or all
three) are typically used as the basis of the design calculations. Before doing the filter
press design calculations, the following specific parameters should be identified, if pos-
sible, from these sources:
Sludge flow rates and solids concentration from each process generating
sludge.
A representative or composite density or specific gravity of the wet sludge
feed stream or streams.
A determination of sludge conditioning chemical dosages required, usually
based on a weight percent of dried sludge solids.
Minimum dry solids allowed in the cake by percent weight of wet sludge feed.
A representative or composite density or specific gravity of the wet sludge
cake.
A determination of the sludge cake thickness.
A determination of the filtrate solids content.
A determination of operating time (i.e., 8 hour/day).
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