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Richness of drilling sludge taken from an oil field quagmire: potentiality and environmental interest
Mansour, D.; Nasrallah, N.; Djenane, D.; Amrane, A. & Maachi1, R.
Abstract
The drilling sludge represents a complex environment,
containing several types of pollutants that can be
even used as nutrients by indigenous microorganisms, like
hydrocarbon-degrading bacteria, having good potentialities
for the biodegradation of petroleum products. In this study, a
drilling sludge was collected from drilling quagmire.
Physicochemical characterization of the drilling sludge was
done. Its mineralogy was obtained by diffractometry. The
indigenous aerobic sludge hydrocarbon-degrading bacteria
were checked by counting on Bushnell–Haas medium, and
their isolation and purification were performed by the
selective microbial enrichment technique in a batch-enriched
Bushnell–Haas culture, with crude oil as the sole
carbon source. Isolates were characterized, and their power
to emulsify crude oil was determined by emulsification
index and oil spreading tests. Environmental conditions in
the quagmire, like temperature, pH and moisture, were
suitable for bacterial development. Physicochemical characteristics
of the drilling sludge showed richness in chemical
elements and promote microbial life. Fifteen different
colonies of hydrocarbon-degrading bacteria were isolated
and purified; they have diversified morphological and
microscopic aspects. Most isolates had a good emulsification
index (between 31 and 76 %). Oil spreading test gave clear
zone diameters>28 mm, with a maximum of 60 mm. The
results of these investigations prove the elementary, mineralogy
and microbiology richness of drilling sludge and
reveal the high diversity of its indigenous hydrocarbon-degrading
bacterial flora. These properties can be exploited for
the own restoration of petroleum quagmires in oil fields, by
means of bioremediation applications and by integrating
indigenous microorganisms.
Keywords
Bioremediation; Drilling sludge; Hydrocarbon-degrading bacteria; Petroleum industry pollution; Physicochemical characterization; Sustainable environment
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