11    ACCELERATED IN-SITU BIOREMEDIATION OF
CUTTING OIL CONTAMINATED SEDIMENTS USING
OXYGENATED NUTRIENT WATER
Glenn R. Gustafson, Graduate Student
Walter J. Maier, Professor
Dept. of Civil Engineering
University of Minnesota, Minneapolis, Minnesota 55455
ABSTRACT
The Superfund site near Morgan Park, Minnesota has been severely contaminated by cutting
oils (6.47 wt %) and small concentrations of polynuclear aromatic hydrocarbons (PAHs). In-situ
bioremediation studies were carried out on a composite sediment sample using a series of continuous flowthrough columns to study the treatability at high and low oxygen additions (i.e., air or
pure oxygen sparging). It was shown that the masses of oil and PAHs were removed at a significantly larger rate using high oxygen addition. The removal of oil and PAHs using high oxygen
addition was 30.6% and 41.6%, respectively.
INTRODUCTION
Sediments contaminated with petroleum products are a continuing source of pollution for the
waters in the Great Lakes, in general, and harbor areas specifically. Polynuclear aromatic hydrocarbons (PAH's) are of particular concern because they are toxic to benthic communities, cause
tumor epizootics in fish, and public health concerns. Relatively little progress has been made in
cleaning up these sources of water pollution and new technologies are needed that can be applied
at relatively low cost.
Researchers have shown that in-situ bioremediation of petroleum contaminated soils and sediments is a promising and cost-effective technology. Hildebrandt and Wilson1 performed one case
study where aerated-nutrient water was cycled through a berm of petroleum contaminated soil.
The soil was determined to be contaminated with oil and grease at a concentration of 1000
mg/kg dry soil and was successfully bioremediated below the available detection limits of 50
mg/kg dry soil after an eight week period. This is an overall approximate removal of 95% of the
contaminants added in a relatively short period of time.
In contrast to the claim that PAHs are recalcitrant to microbial populations, research has shown
that PAH removal does occur. Aprill et al.2 showed that PAH removal was as high as 71%. Aprill
showed that even the higher molecular weight PAHs (i.e., fluoranthene, pyrene, benzo(a)an-
thracene, and chrysene), which are much more recalcitrant than low molecular weight compounds, show a degradation as high as 53%.
This research concentrates on a Superfund site contaminated with cutting oils which contain
low concentrations of PAHs. The site was contaminated from the USX steel mill operations located at Morgan Park, MN on the St. Louis River. The site is approximately 230 acres in area
and the contamination extends to levels of 2 to 20 ft into the sediments. Most of the contaminated sediments are in a shallow area of the estuary with water levels ranging from 0 to 2 ft in
depth.
Preliminary site investigations showed that the dissolved oxygen concentrations were below
the limits of detection for the groundwater in the estuary. Exploratory laboratory tests also
showed that addition of oxygen resulted in rapid aerobic biodegradation. This indicates that engi-
52nd Purdue Industrial Waste Conference Proceedings, 1997, Ann Arbor Press, Chelsea, Michigan 48118. Printed in
U.S.A.
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