MIL-HDBK-1005/9A
b) Pilot studies are essential in selecting the optimum
filter. Design should be based on economic tradeoffs between
filter size, operating head requirements, and run length for a
specific effluent quality. Refer to EPA PB 214551, Process Design
Manual, Suspended Solids Removal, for methodology for making this
comparison.
c) Gravity filter tanks can be constructed of either
reinforced concrete or carbon steel. Pressure filters are
normally prefabricated package units built in carbon steel
pressure tanks. Carbon steel tanks should be specified to have
both interior and exterior surfaces blast cleaned, prime coated,
and finish coated with a coal-tar epoxy.
3.10.7.2 Coalescing Filtration. A coalescer system consists of a
prefilter followed by two stages of coalescer elements. The
prefilter removes free oil and solids and can be either a
mechanical pack or disposable cartridges. The coalescing
elements, often cartridges, remove dispersed and some emulsified
oil to below 10 ppm. Eventually, the elements become blinded and
must be replaced.
a) Equipment. Coalescing filtration units are
available as prefabricated package units. Specify tankage
fabricated of carbon steel with interior and exterior surfaces
blast cleaned, prime coated, and finish coated with a coal-tar
epoxy system. Specify maximum use of stainless steel for internal
components including mechanical coalescer packs, piping, and
cartridge and filter supports or brackets. Prefilter and
coalescer cartridges are manufactured from a variety of synthetic,
noncorrosive materials. Figure 24 shows a typical arrangement of
components for a coalescing filtration unit.
3.10.7.3 Activated Carbon Adsorption. Polishing of oily
wastewater by activated carbon adsorption produces effluence of
high quality containing less than 10 mg/L oil and grease and low
levels of dissolved organics. A large number of compounds listed
as toxic on EPA's priority pollutants lost are amenable to removal
by this treatment.
160
Previous Page
