UFC 3-280-03
23 JULY 2003
CHAPTER 2
DESIGN CONSIDERATIONS
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INTRODUCTION. Filter presses have been used successfully to dewater and
reduce the volume of sludge for domestic wastewater treatment facilities since the mid-
1800s. However, it was not until around 1970 that they received widespread acceptance
as a practical sludge-dewatering alternative. In addition to traditional wastewater
applications, filter presses are currently being used to reduce and minimize the volume
of sludge being generated from water and wastewater and other treatment operations at
hazardous, toxic, and radioactive waste sites, including types of remediation projects
being performed for the Corps of Engineers, and may be the most appropriate
dewatering option.
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Purpose. This chapter provides design considerations for engineering and
design of plate and frame filter presses. These engineering and design procedures will
be applicable to all DOD projects. However, this documentation is specifically applicable
to the hazardous, toxic, and radioactive waste (HTRW) programs and should be
adapted to the requirements of other programs.
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Scope. This document covers the applicability and use of plate and frame
filter press technology, equipment, and ancillary technologies and equipment. Two pri-
mary systems are described: fixed-volume and variable-volume (diaphragm) recessed
plate and frame filter presses.
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References. A list of references, other supporting documentation, and litera-
ture used in the development of this chapter is presented in Appendix A.
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Background. Pressure filtration for dewatering sludge evolved from a similar
technology used to manufacture sugar by forcing juices through cloth (EPA 1979). The
technology was first used successfully during the mid-1800s in England for dewatering
sludge without chemical precipitation (WPCF 1983). The technology was first used in
the United States from 1898 to 1917 in Worcester, Massachusetts. Until the 1970s, filter
presses were not widely considered because of the large amount of manual labor
required. However, with mechanization and automation of internal systems, such as
plate-shifting, cake discharge, and filter cloth washing, from a batch to an automated
system, the overall labor requirement decreased dramatically. In addition, the capacity
of these units increased substantially, decreasing the number of presses required and,
thus, reducing overall operations and labor requirements. Currently, recessed fixed- and
variable-volume filter presses are used in both municipalities and industry.
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Theory. Pressure filtration separates suspended solids from a liquid slurry
using a positive pressure differential as the driving force. In general terms, filter
pressure dewatering may be described as a combination of constant flow rate and
constant pressure processes. In the beginning of the filter cycle, a constant flow rate is
used to build a maximum pumping head. When the maximum pumping head is
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