F
ats, oils, and grease (FOG) from municipal
wastestreams are widely variant from each
other, as municipal wastestreams tend to
be. It is also maddeningly difficult to obtain
meaningful data for FOG, partly due to this variance
and partly because FOG are natural products. What
will or won't work for the removal of FOG is never
universal, but there are parameters for success.
All FOG wastestreams contain hydrophobic
components, meaning they contain "water-hating"
parts that are insoluble in water. These hydrophobic
components are usually less dense (lighter) than
water and float on the surface. This results in clogging
masses interfering with the physical and chemical
functioning of the treatment process — both the
collection and the actual treatment of the wastestream
at the wastewater plant. This floating mass entrains
other floating debris, making it even more difficult
to remove. In short, this is probably the biggest and
most aggravating problem that those working with
collection systems and treatment systems encounter.
Keys To Overcoming FOG
The successful removal, alleviation, and control of FOG
deposits in wet wells, lift stations, and grease traps will
involve both physical and chemical considerations.
The key parameters are:
1. providing oxidation potential to the deposits, and
2. providing a means to increase the surface area (and
thereby the reactivity) by decreasing the size of
components of the deposits into microparticulates.
FOG microparticulates are defined in wastestreams
as very small hydrophobic organic particles (either
solid or liquid, as in the case of emulsoids) that are
stable within the wastestream. The solid's structure
on a macromolecular level may be lamellar (as in a
composite or crystalline material, such as graphite)
or branched (as in steel wool). The surface of
these solid microparticulates is generally referred
wateronline.com
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Water Online The Magazine
Shear Power:
How To Defeat FOG Once And For All
Overcome the problem of fats, oils, and grease (FOG) by understanding it and choosing the right equipment.
By Dr. J.H. Wakefield
FOG composition is varied, but often thick and sedentary. Great balls of FOG: Balls of grease clog the collection system.
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