Treat Hydrocarbon Processing Industrial
Wastes with Bugs
DUANE B. SKOGEN, Process Superintendent
Continental Oil Company
Billings, Montana
By use of biological oxidation ponds, known more affectionately by refinery personnel as "bug ponds", Continental Oil Company has reduced major pollutants in the waste water effluent of its Billings Refinery by over 90 per cent. The rate
of water biologically treated averages 225 gpm, and the daily operating cost amounts
to $145 per day.
In 1962, Continental Oil Company engineers and refinery personnel embarked
on a long range program to clean up the refinery's waste water effluent. At the time
the only waste water treatment facility in the plant was an API oil separator, through
which flowed all the waste water except the boiler plant and recirculating cooling
water system blowdown streams. The boiler plant blowdown stream relied on pots
installed at intervals in the blowdown sewer to reduce solids content. With these very
limited facilities the plant effluent water stream generally exceeded receiving water
standards for phenol, sulfides, oil and suspended solids.
A waste water survey and pollution abatement analysis indicated the need for
three waste water collection and treatment systems. These systems have been completed in a step wise program, with the major additions occurring in 1962, 1964,
1966, and 1969. Minor additions and refinements have been and will be a continuing
project as conditions warrant.
The first system collects sour waters - the source of these waters is primarily
condensed steam which has been in contact with oil during the refinery process, and
is contaminated with phenols, sulfides, and ammonia. This is a very extensive system
since there are many sources of sour water in a refinery, some of them as small as
one-half gpm. The streams are pumped or pressured into a main receiving drum. The
receiving drum is equipped with an internal oil skimmer and is vented to the flare.
The sour water is pumped on level control from the receiving drum to a
stripper tower where the water is steam stripped to reduce the concentration of
sulfides and ammonia. The stripped sour water is then pumped through an aerial
cooler to the first of the two aerated bio ponds that operate in series. The reason for
reducing the sulfide and ammonia concentrations prior to feeding the water to the
bio ponds is the "bug" population prefers sulfides to phenols, preferentially consuming the sulfides and leaving the phenols. Ammonia makes them sick and inactive. The
two bio ponds are operated in series so that in the event of a bio pond feed upset
resulting in sick bugs in the first pond, the population of the second pond completes
the clean up job. Only rarely has a feed upset resulted in the second pond also
becoming partially inactive. Bug ponds generally are very sensitive to feed concentra-
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