17 DEC 2003
Table 6-1. Commonly Encountered O&M Problems
Unacceptable levels of turbidity in efflu-
Pre-treat with chemicals or polymers, or
ent before terminal head loss is
both, upstream of the filter bed.
Reduce solids loading through pre-
filtration solids removal, such as
Masses of solids, dirt, and media, the
Auxiliary washing processes (e.g., air
mudballs sink into the filter bed,
scour, surface wash) with, or followed
reducing the effectiveness of filtering
by, water wash
Buildup of grease
Oil or grease emulsifying within the
Air and surface wash usually help.
May be necessary to install washing
system using special solutions.
Pre-treat for oil and grease.
Carbonate buildup on media after lime
Acid rinse or, for small systems, replace
Influent pH adjustment.
Develop when filter bed is not cleaned
Adequate backwash and scour.
Loss of media
Correct placement, sizing of wash water
troughs, and underdrain system.
Correct backwash flow or pressure.
Gases coming out of solution in the
Backwash at terminal head loss no
water because of negative heads.
greater than the depth of submergence
of the top of the filter media or increase
Support gravel disruption during
Overlay gravel support layer with layer of
high density material, such as ilmenite or
Correct backwash flow rate or pressure.
Filter element clogged without alarm
Change elements and check alarm for
Filter element damaged.
Change element more frequently and look
for waste stream components that could
damage filter fabric.
Filtration system improperly sized for
Increase the number of filter elements
operating in parallel.
If allowed by the application, increase the
cartridge removal rating so that fewer
solids are retained.
Influent pretreatment to reduce solids
The growth of a biologic mass, such as
Chemical pretreatment at the source or
algae, either within the waste stream or
within the treatment process using
the treatment process, that creates a
solids loading of a concentration and
Identify the factors contributing to bio-
character that cannot be effectively
mass growth (e.g., heat, excessive
holding time, high organics in the waste
stream) and eliminate them.