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Failure of upstream conveyors should cause sequential shutdown of down-
stream conveyors or sequential treatment processes. This should be timed
based to ensure that the previous load on the downstream side has been
conveyed or processed.
(5) The sludge cake receptacle interlock should ensure that the sludge cake
receptacle (i.e., dumpster or truck) is in place before the sludge cake is discharged. This
is essential when the filter operator cannot see the receptacle. For this type of system, a
manual push-button could be used. Electric eye devices or load cells could also be
2-4.7.3 Specific Control Elements. The filter press and supporting systems can be
equipped with several types of control elements, depending on the degree of control
desired. The types of specific control elements for a filter press system may include
sensors, meters, interlocks, controllers, control valves, and recorders. Further informa-
tion for these types of control elements are presented in WEF (1992).
Sludge Cake Handling and Storage.
2-4.8.1 Sludge Cake Handling. Sludge cakes are typically handled either by
dumping them directly into a bunker below the unit for storage or by dumping them onto
a conveyor for subsequent processing or storage. The specific cake handling method
used primarily depends on the ultimate disposal method. For example, if an offsite
disposal method such as landfilling or incineration is to be used, the sludge may be
deposited directly into a storage container or truck.
Storage containers typically used for smaller presses are extended platforms
equipped with drum or roll-off box chutes and appropriately sized storage containers.
For example, for smaller presses (i.e., 18 to 24 inches [470 and 630 mm]) a drum
platform chute may be better than the roll-off platform or direct discharge into trucks,
whereas the roll-off platform and chute may be better for the 0.7-m3 (25-cubic yard) roll-
off box. When using direct discharge into trucks, the filter press may need to be
elevated, adequate space should be allowed for the trucks or containers to be loaded
and unloaded, and an ample number of trucks should be available for the anticipated
volume of sludge generated.
For further onsite treatment, such as sludge cake drying and incineration, or
remote loading for offsite disposal, two potential sludge cake handling methods using
conveyor systems could be used. The first method provides storage directly below the
press and a conveying system that leads to the onsite treatment device. The second
method includes a conveying system from the press to an intermediate storage facility
between the press and onsite treatment device. The accumulated sludge in
intermediate storage would be subsequently metered to the onsite treatment device.
Typical sludge conveying systems are further described in Subparagraph 2-4.9.1. For
additional information on thermal processing methods (i.e., sludge drying and
incineration), equipment, and design criteria, refer to WEF (1992).