23 JULY 2003
Table 2-9. Most common design and operational shortcomings
of filter press installations.
Blinding of filter cloth and poor cake
Switch conditioning chemicals or
Insufficient filter cloth washing.
Blinding of filter cloth, poor cake
release, longer cycle time required,
Inability to transport dewatered
Cake buildup and spillage onto the
Install cake breakers; redesign
cake from dewatering building.
angle of screw conveyors or belt
conveyors to 15 degrees maximum
angle. Alternatively, use a heavy-
duty flight conveyor.
Improper filter cloth media
Poor cake discharge; Difficult to
Poor cake release.
(1) Try two-stage compression
Inadequate facilities when
"pumping" cycle with first stage at
dewatering a digested sludge
low pressure to build up dewatered
with a very fine floc.
sludge on the filter media before
increasing to the second-stage
higher operating pressure.
(2) If this fails, vary conditioning or
install precoat storage and feed
Feed sludge is too dilute for
Long cycle time and reduced
Thicken sludge before feeding to
efficient filter press operation.
Sludge feed at only one end of
Unequal sludge distribution within the
large filter press.
pump to feed at opposite end of
Remedial measures for this problem include the use of reinforcement, such
as an extra layer of material, or use of a different type of material, or the use of stainless
steel covers that fit directly over the cloth media and stay boss. However, if the former
method is used, care should be taken to ensure that the additional layer of thickness is
equal to that around the perimeter of the plate to ensure proper sealing and to minimize
the potential for plate deflection.
2-22.214.171.124 Stay Boss Deterioration. Stay bosses deteriorate from excessive wear
caused by plate deflection. This wear increases the flexing of the plate and ultimately
breaks the plate. Therefore, stay bosses should be regularly inspected for deterioration
and repaired as required. Stay boss deterioration can also be minimized by following
the remedial measures listed for plate deflection in Subparagraph 2-126.96.36.199.