v°/EPA
United States
Environmental Protection
Agency
EPA/540/M5-91/002
August 1991
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Demonstration Bulletin
AquaDetoj^/SVE System
AWD Technologies, Inc.
Technology Description: The AWD technology simultaneously
treats groundwater and soil-gas contaminated with volatile or-
ganic compounds (VOC), such as trichloroethylene (TCE) and
tetrachloroethylene (PCE). This technology integrates two pro-
cesses: (1) AquaDetox®, a moderate vacuum (pressure about 50
mm Hg or greater) stream stripping tower that treats contami-
nated groundwater, and (2) a soil vapor extraction (SVE) system
that removes contaminated soil-gas for subsequent treatment
with granular activated carbon (GAG) beds. The two technologies
are integrated into a closed-loop system, providing simultaneous
remediation of contaminated groundwater and soil-gas with no air
emissions. The major components of the integrated AquaDetox®/
SVE system are shown in Figure 1.
AquaDetox® is a high-efficiency, countercurrent stripping tech-
nology developed by Dow Chemical Company. Stripping is com-
monly defined as a process that removes dissolved volatile com-
pounds from water. A carrier gas, such as air or steam, is
purged through the contaminated water, with the volatile compo-
nents being transferred from the water into the gas phase. Ac-
cording to the developer, the AquaDetox® technology can be
used to remove a wide variety of volatile compounds, as well as
many compounds that are normally considered "non-strippable"
(i.e., those with boiling points in excess of 200°C).
SVE is a technology commonly applied for the in-situ removal of
VOCs from soil. A vacuum is applied to vadose zone extraction
wells to induce air flow within the soil toward the wells. The air
acts as a stripping medium that volatilizes the VOCs in the soil.
Soil-gas from the extraction wells is typically treated in GAC beds
before release to the atmosphere/Alternatively, the treated soil-
gas can be reinjected in the soil to control the direction of air flow
in the soil.
The AquaDetox® and SVE systems are connected in a closed
loop. Non-condensable vapors from the AquaDetox® system are
combined with vapors from the SVE compressor and treated
using two GAC beds in series. The GAC beds are regenerated
periodically using steam. The regeneration steam removes the
adsorbed contamination from the GAC as it moves upward through
the bed. ft is then condensed and sent to the AquaDetox® tower
for treatment.
Recovered organics are collected in an on-site storage tank and
are periodically trucked to an off-site facility for recycling.
Waste Applicability: The AWD technology is designed to
treat groundwater and soil contaminated with volatile and semi-
volatile organic compounds. Desirable soil characteristics for
successful soil vapor extraction are high permeability, large grain
size, and a low moisture content. However, for soils with even
moderate permeability (permeability range about 1Q-3 to 10* cm/
sec), sufficient air flow for removal of contaminants is possible.
Demonstration Results: The AWD technology was demon-
strated over a 2-week period in September 1990 at the Lockheed
Aeronautical Systems, Inc. facility in Burbank, California. The
testing plan consisted of 21 test runs performed under varying
operating conditions. The test runs were grouped into six phases.
Phase 1 test runs were performed at AWD-specified operating
conditions (tower pressure at 105 mm Hg, steam flow rate at
3,800 Ib/hr, and groundwater flow rate at 900 gpm). The steam
flow rate was varied in Phase 2 test runs. Steam flow rates and
tower pressures were varied simultaneously in Phases 3 and 4.
The groundwater flow rate was varied in Phase 5 test runs.
Phase 6 involved the SVE system in which the GAC bed regen-
eration frequency was varied.
Based on the analytical results and observations from the AWD
SITEE demonstration, the following conclusions were made about
the technology's effectiveness and cost.
• The AWD technology can successfully treat groundwater and
soil-gas contaminated with VOCs.
• The efficiencies were in the 99.92 to 99.99 percent range for
removal of VOCs from contaminated groundwater. VOC removal
efficiencies for soil-gas ranged from 98.0 to 99.9 percent when the
GAC beds were regenerated according to the SWD-specified
frequency (8-hourshifts). VOC removal efficiencies dropped to as
low as 93.4 percent when the GAC beds were regenerated less
frequently.
• The AWD technology produced effluent groundwater that com-
plied with regulatory discharge requirements for TCE and PCE (5
(xg/L for each compound ) at the Lockheed site throughout the
SITE demonstration. In addition, routine sampling by Lockheed
has shown that the effluent groundwater has been in compliance
with the regulator requirements throughout the 2-year operation
of the system with no reported violations.
• The GAC beds effectively removed VOCs from contaminated
soil-gas even after 24 hours of continuous operation without
steam regeneration
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• The AquaDetox® system proved highly effective in removing
VOCs such as TCE and PCE (boiling points up to about 120°C)
from contaminated groundwater. The system should also be
effectiveforlessvolatileorganics (boiling points in excess of 200°C
according to the developer). However, because higher boiling
point organlcs were not present in the groundwatertreated during
the AWD SITE demonstration, the system's effectiveness in re-
moving this type of contamination could not be evaluated. Water
containing such organics should be subjected to a treatability
study.
• The system's steam consumption dropped with decreasing tower
pressures. During the demonstration, the system proved more
efficient at lower operating tower pressures.
•The system has been operating successfullyfor over2 years at the
Lockheed site. During this time period, the system has been
operational for 95 percent of the time, with 5 percent down time due
to scheduled or non-scheduled repairs.
respectively. The total annual operation and maintenance costs
are approximately $410,000, $630,000, and $1,500,000 for the
500-, 1,000-, and 3,000-gpm systems, respectively.
A Technology Evaluation Report and an Applications Analysis
Report describing the complete demonstration will be available in
the Summer of 1991.
For Further Information:
EPA Project Managers:
Gordon Evans (513-569-7684 or FTS 684-7684)
Norma Lewis (513-569-7665 or FTS 684-7665)
Risk Reduction Engineering Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
26 West Martin Luther King Drive
Cincinnati, OH 45268
• The AWD system is estimated to cost approximately $3.2, $4.3,
and $5.8 million for the 500-, 1,000-, and 3,000-gpm systems,
Rerun Water
Tank
Control Room
Granular Activated
Carbon Beds
Containment
Berm
Vacuum Pump
Gravity Separator
Note:SourGO of Steam Not Shown
Aquadetox
Stripping Tower
Solvent
Storage Tank
Condenser
Heat Exchanger
United States
Environmental Protection
Agency
Figure 1. Isometric View of the AWD Integrated AquaDeto,
Center for Environmental
Research Information
Cincinnati, OH 45268
'stem.
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/540/M5-91/002
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