Separation of Oil from Wastewaters with
Crushed Graphite Ore
EARNEST F. GLOYNA, Director
SIDNEY O. BRADY, Associate Director
Center for Research in Water Resources
The University of Texas at Austin
Austin, Texas
PEDRO MARTINEZ-PEREDA, Professor
Sanitary Engineering Department
University of Mexico
Mexico City, Mexico
INTRODUCTION
Removal of suspended solids by filtration through beds of porous media is one
of the oldest and most widely used processes in water treatment. However, relatively
little use has been made of this process for removal of emulsified oil from water.
Primary treatment of oil wastewater by a conventional method such as a
gravity separator tank or other settling basin is usually not sufficient to meet the
required effluent quality criteria. Usually after primary treatment by gravity
separation, the effluent contains 30 to 150 mg/l of emulsified or soluble oil. In terms
of oil globule size, separators usually are effective over a globule diameter range
having a lower limit of 0.015 cm (15 microns) and therefore such units will not
separate oil globules of smaller size, nor will they break emulsions. Therefore, an
additional treatment is becoming desirable and as an alternative high-rate filtration
should receive consideration.
Although a few references are found in the literature to the use of rapid sand
filters for removal of oil from water, there is a distinct lack of technical articles on oil
filtration. It is known that the petroleum producing industry is using some
proprietary filter equipment to remove oil from the brine produced with crude oil.
Again there appears to be a dearth of useable information on the subject in available
literature.
With the imposition of stricter quality standards on all effluents discharged
into surface waters, it is imperative that more effective wastewater treating methods
be developed. The development of new uses for old proven processes may be a
simple, economical and effective means of helping to meet the more rigid standards.
Source and Characteristics of Waste Oil
The oil used in these experiments was a typical slop oil from a major refinery.
Stable  emulsions  formed  in  the  sewer-separator  system are filtered on vacuum
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