'    THE DESIGN, ECONOMICS, AND OPERATION OF A
BIOLOGICAL TREATMENT SYSTEM FOR KETONE
CONTAMINATED GROUND AND SOLVENT
RECOVERY PROCESS WATERS
George J. Skladany, Research Manager
DETOX, Inc.
Dayton, Ohio 45459
Jeffrey M. Thomas, Western Regional Manager
DETOX, Inc.
San Francisco, California 94103
Greg Fisher, Corporate Environmental Engineer
Rom Ramachandran, Staff Safety & Corporate Environmental Engineer
Memorex Corporation
Santa Clara, California 95054
INTRODUCTION
The MEMOREX Computer Tape Plant in Santa Clara, California uses several solvents in the
production of magnetic tape. The discovery of contaminated ground water due to a leaking underground solvent storage tank prompted the company's engineering staff to initially investigate different
ground water remediation technologies as well as search for ways to improve the facility's overall
hazardous waste handling program. The immediate need was to locate, control, and remediate a
ground water plume containing several solvents. Secondary needs at the plant included instituting a
hazardous waste treatment program, and to reduce both the liability and costs associated with off-site
disposal of hazardous materials.
INITIAL GROUND WATER CONTAMINATION PROBLEM
An environmental investigation at the plant identified a localized ground water contaminant plume
downgradiant of the underground solvent tank farm. A leaking storage tank was identified and
removed. Monitoring wells were installed at the facility to identify the vertical and horizontal extent
of the problem, and an extraction well was installed to hydraulically contain the contamination and
transfer water to the surface for treatment. A single well pumping at 15 gpm was able to capture the
entire plume. Chemical analysis of the ground water identified the presence of methyl-ethyl ketone
(MEK) up to 500 mg/L, xylenes & ethyl benzene up to 40 mg/L, cyclohexanone up to 30 mg/L,
cyclohexanol up to 10 mg/L, acetone up to 10 mg/L, and toluene, tetrahydrofuran, 2-butanol, and
methyl-propyl ketone each less than 1 mg/L. Initial MEK concentrations were expected to decrease
rapidly with treatment. The treatment system was required to handle a continuous flow of 15 gpm,
and had to attain effluent MEK concentrations of less than 1 mg/L and other total organics concentration less than 100 Mg/L.
Initially, a carbon adsorption system was installed at the site to provide emergency treatment of the
contaminated water. Required effluent treatment levels from the carbon system were set at 1 mg/L for
discharge to the local sanitary sewer. The carbon system had many operational problems treating the
ground water. Activated carbon has only limited affinity for MEK, thus the system was not able to
consistently reduce MEK concentrations to less than 1 mg/L. In addition, odor problems developed
within the system. Bacteria able to readily biodegrade the contaminants present in the ground water
began growing on the activated carbon, depleting the water of dissolved oxygen. Without free oxygen,
the bacteria then began using oxygen present in dissolved sulfates as a terminal electron acceptor,
reducing sulfate to hydrogen sulfide. Hydrogen sulfide caused the characteristic "rotten egg" smell
present in the system effluent.
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