UFC 3-280-04
17 DEC 2003
5-3.4
Advantages/Disadvantages. Cartridge filters are flexible in that different rat-
ings and materials of construction can be interchanged to accommodate changing con-
ditions in waste streams. Multiple cartridges housings are available to supply the sur-
face area needed to meet desired throughput and flow rate while minimizing pressure
drop. Multi-cartridge housings also have the advantage of requiring little space. Multi-
cartridge housings can be anywhere from 216 mm (8.5 in.) to 914 mm (36 in.) in di-
ameter and 2261 mm (89 in.) to 3277 mm (129 in.) in length, depending on the manu-
facturer and the number of cartridges installed within a single unit.
5-3.4.1 Cartridge filtration can be used for any flow rate simply by adding more filter
area. Some applications have flow rates of 4 to 8 million L/day (1 to 2 mgd), such as in
the semiconductor industry. In this application the wet stream undergoes rigorous pre-
treatment to minimize changing of filter elements. For HTRW applications, cartridge fil-
ters can be used to remove pinpoint flocs not readily removable by granular media fil-
ters. In addition, there is no need for backwash tanks, or pumps, and there is no need
for upstream treatment. As discharge limitations become more stringent, cartridge filtra-
tion will have a larger role at HTRW sites.
5-3.4.2 The biggest limitation for cartridge filters is their inability to treat waste
streams with solids loadings greater than 1 or 2 mg/L. Higher solids can be handled but
only through the addition of more filter elements. For this reason cartridge filters are of-
ten used as a polishing step or to protect a downstream treatment unit subject to bio-
logical or particulate attack. On an equivalent-flow basis, for a waste stream with a
moderate level of suspended solids, filter cartridges would often be more expensive
than granular media owing to the greater required frequency of cartridge change out
(i.e., higher O&M costs for cartridge relative to granular media in this situation).
5-3.4.3 Disposable cartridge filters are limited in use on hazardous waste sites be-
cause the cartridge housing needs to be opened to replace filter elements. This creates
health and safety concerns. Such concerns include possible exposure to vapors and
dermal contact during cartridge removal, thus necessitating increased levels of personal
protective equipment. When used in treating hazardous waste, the costs for disposal of
a single cartridge is significant when compared to the total quantity of contaminant re-
moved. Other systems that can be backwashed have the advantage of being able to
remove the solids from the filter bed without disposing of the media. Because there is
no need to change the media, as with cartridge filtration, there can be significant cost
savings. However, it should be noted that capital costs for cartridge filter systems are
typically less than for other types of filtration systems (e.g., pressure or gravity granular
media systems).
5-4
BAG FILTRATION
5-4.1
Description of Unit. Bag filtration is similar to cartridge filtration in that it uses
numerous types of fabricated media enclosed in housings, and that the filter media and
housings are constructed of materials compatible with the waste stream being treated.
Some bag filters may be backwashed to extend media life and operation. Bag filters are
effective at straining slurries and dispersions and removing particle sizes in the range of
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