PROCESS CONSIDERATIONS IN LAND TREATMENT
OF REFINERY SLUDGES
Thomas G. Sprehe, Engineer
Solid and Hazardous Waste Division
Post, Buckley, Schuh, and Jernigan, Inc.
West Palm Beach, Florida 33401
Leale E. Streebin, Director
James M. Robertson, Professor
Paul T. Bowen, Assistant Professor
School of Civil Engineering and Environmental Science
University of Oklahoma
Norman, Oklahoma 73019
INTRODUCTION
Land application of various wastes has been practiced worldwide for over 100 years. Today, many
industrial wastes, including petroleum refinery sludges, are applied to land for treatment and disposal
on an ever-increasing basis. Studies completed to date show that land treatment can be an environmentally safe technique for both biological and oily sludge disposal. When land area is readily available, land treatment is usually more cost effective than other disposal methods, including landfilling.
The relative simplicity of operation is a major advantage. However, operational simplicity can lead
to quick abuse, especially in the absence of rational guidelines for process design and operation.
As part of EPA's Hazardous Waste Land Treatment Research Program, an extensive field project
was undertaken at the University of Oklahoma to evaluate and optimize physical, chemical, biological, and operational factors which control the process of land treatment of oily sludge [1]. The
purpose of the research was to study the land treatment process for treatment of API separator sludge
in order to establish operational guidelines and a rational basis for process design. It was recognized
that the usefulness of such guidelines would be less in their application to situations closely matching
the conditions of the subject study than as a general approach applicable to a variety of oily waste
types and site conditions.
Specific objectives were to determine optimum sludge loading rates and application frequencies,
as well as to identify operational considerations important to the process. Additional research objectives were to study the fate of selected priority pollutants commonly present in oily sludges, and
to assess the volatile atmospheric emissions from their application to land. In assessing volatile emissions from land treatment, the objectives were to: 1) determine the rate and magnitude of fugitive
hydrocarbon emissions; 2) evaluate and model the effects of parameters such as sludge loading rate,
temperature, soil moisture, and relative humidity on the quantity of emissions; and 3) identify and
quantify individual compounds being emitted. Volatile emissions were thus accounted for in the oil
mass balance equation.
PROTOTYPE FIELD FACILITY
In order to gain as much practical insight into the land treatment process as possible, a full scale
prototype field facility was constructed and actual refinery API separator sludges treated. A ten-acre
site owned by the University of Oklahoma was selected for use in the study. The site soil, a bethany
silt loam, was underlain by several hundred feet of impermeable clay. The site was designed to hold
a maximum of 50 plots, 2.7 m x 6 m (9 ft x 20 ft). Twenty-foot buffer zones were provided to
minimize material transfer between plots. This spacing also made it convenient to maneuver the
tractor and applicator to each plot. The site was diked and provided with a stormwater retention
pond. Two tanks for on-site storage of the API separator sludges were provided with a total capacity
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