UFC 3-280-03
23 JULY 2003
if the operation is based on a 5-day work week instead of a 7-day week, the dewatering
equipment would need to be sized to store a portion of the additional sludge generated
or have a filter capacity greater than the daily sludge volume capacity generated.
Typically, it is assumed the filter press will only be operated during one shift operating 8
hours per day in a 5-day work week.
2-7.3.2 Equipment Requirements. Sizing criteria are also applied to the equipment
associated with the plate and frame filter press and supporting systems, such as
chemical handling (i.e., conditioning) and storage.
2-7.3.2.1 Sludge Processing Units. The following are general requirements that
should be considered in sizing and designing the sludge processing units (GLUMRB
1990).
a. General Provisions. Service should be maintained so that sludge may be
dewatered without accumulating beyond the storage capacity. Multiple units with a
capacity to dewater the design sludge flow with the largest capacity unit out of service
should be available, or facilities should be available to store the sludge from at least 4
days of operation, unless other standby dewatering facilities are available.
b. Ventilation. Adequate ventilation for the dewatering area should be
provided to avoid nuisance odors or hazardous fumes. Additional provisions for
ventilation are described in Subparagraph 2-9.8.2.
c. Chemical Handling Systems. Facilities used for chemical handling should
be automated as much as possible to limit personnel exposure from manual operations.
In addition, facilities that generate dust, such as lime mixing facilities, should be
enclosed to prevent escape of dust.
2-7.3.2.2 Sludge Storage. The following general requirements should be considered
for either liquid sludge or sludge cake storage units (GLUMRB 1990).
a. General Provisions. Appropriate storage should be provided for both liq-
uid and dried sludge.
b. Storage Capacity. A storage facility capable of storing 4 days' production
volume should be provided unless other standby dewatering facilities are available.
2-7.4
Cycle Time. Cycle time also plays a major role in the sizing of equipment.
The cycle time not only consists of the time required for the filtration cycle, but also
includes the time required for cake discharge and other operations, such as filter media
washing. Cycle time primarily depends on the filtration period and degree of desired
cake dryness. Typical cycle times for sludge dewatering in various fixed-volume and
variable-volume filter presses are presented in Tables 2-4 and 2-5, respectively. Based
on the anticipated sludge loading divided by the cycle time and operations and labor
requirements, the sludge volume and optimum number and size of filter presses
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