TREATMENT OF TAR SAND PROCESS
WATERS BY MEANS OF TWO-STAGE,
POLYMER-AIDED, AIR FLOTATION
Marie H. Bushway, Graduate Student
Gregory D. Boardman, Associate Professor
Department of Civil Engineering
Virginia Polytechnic Institute and State University
Blacksburg, Virginia 24061
William F. McTernan, Division Leader
University of Wyoming Research Corporation
Laramie, Wyoming 82071
INTRODUCTION
Finding new sources of petroleum products is one our our nation's greatest concerns. Widespread
deposits of tar sand may help to alleviate this growing shortage of fossil fuel. In the late 1960's the
United States tar sand bitumen resource was estimated to contain between 2.5 and 5 billion barrels
of oil [1J. It is now believed that the reserves contain about 30 billion barrels of oil with 29 billion
barrels present in Utah, alone. Canada and Venezuela are believed to have 900 billion and 1.7 trillion
barrels of oil, respectively, associated with tar sand deposits [2].
The term tar sand refers to consolidated or unconsolidated rock with interstices that contain
viscous or solid bitumen which, in its natural state, cannot be recovered by methods commonly used
in the petroleum industry. To extract bitumen from tar sand, it is necessary to first convert the
material into a form which can be transported to production wells. Among the more promising extraction techniques now recognized are in situ combustion and steam purge methods. The Department
of Energy Office at Laramie and Wyoming Research Corporation (formerly united as the Laramie
Energy Technology Center or LETC) have been studying the two types of recovery methods for
several years. The wastewater used in this study was generated in an in situ steam purge experiment
conducted by LETC in 1980. In this experiment 1,150 barrels of bitumen and 6,250 barrels of wastewater (referred to as TS-IS process waters) were produced [3]. The TS-1S waters contained high levels
of solids and organic matter so some form of treatment would be required before the waters could
be recycled or disposed of in an acceptable manner.
The work described in the following paper was undertaken to investigate the potential of using
a two-stage, air flotation system to treat the TS-1S waters. Earlier studies conducted in our laboratories revealed that air flotation was a viable process, but the configuration and/or operation of
the systems considered previously were/was somewhat different [4, 5]. System performance was evaluated on the basis of changes in total organic carbon, total solids, total suspended solids, total dissolved solids, and chemical oxygen demand.
METHODS AND MATERIALS
The Two-Stage Air Flotation System
A two-stage, air flotation system was developed following the design of single-stage, air flotation
systems used previously in our laboratories (4, 5). A diagram of the two-stage system is provided in
Figure 1. As may be discerned from the schematic, compressed air provided by a Gast compressor
(Gast Manufacturing Corporation, Benton Harbor, MI) was delivered through a pressure regulator
at 10 psi to an air filter, air saturator, rotameter, and stainless steel disc sparger (PTM Corporation
of Cortland, N.Y.). The sparger had a 67 mm diameter and pores less than 3 microns in diameter.
This sequence of components was used to reduce the contaminant levels of the air and to deliver it
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