540MR95525
&EPA
United States
Environmental Protection
Agency
EPA/540/MR-95/525
August 1995
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Demonstration Bulletin
New York State Multi-Vendor Bioremediation
R.E. Wright Environmental, Inc.'s
In-Situ Bioremediation Treatment System
Technology Description: The R.E. Wright Environmental, Inc.'s
(REWEI) In-situ Bioremediation Treatment System is an in-situ
bioremediation technology for the treatment of soils contaminated
with organic compounds. According to the Developer, contami-
nated soils are remediated in-situ by stimulating the activity of
indigenous soil microbes through the introduction of essential
nutrients, an easily oxidized co-substrate and an electron accep-
tor. The technology's primary nutrient amendment, essential for
microorganism growth, is nitrogen in the form of gaseous anhy-
drous ammonia. The technology uses methane as the easily
oxidized co-substrate. Methane stimulates the growth of
methanotrophic organisms and induces the production of an
enzyme (methane monoxygenase) capable of degrading low mo-
lecular weight chlorinated alkanes and alkenes. The electron
acceptor for the aerobic methanotrophic enzyme system is oxy-
gen. Oxygen is distributed throughout the treatment zone at
atmospheric concentrations by use of an air injection system.
Depending on the contaminants' phase and volatility, and particu-
larly during the early stages of remediation when the microbial
consortium has not had adequate time to become established, a
certain portion of the contaminant mass is removed from the soil
by vapor extraction/air stripping. The Developer maximizes bio-
degradation as the principal mechanism for contaminant reduc-
tion by limiting vapor extraction to only the level necessary to
meet biological oxygen demand.
The technology consists of networks of small-diameter bioventing
(extraction) and injection wells which are used to aerate and
introduce amendments into the treatment zone. The bioventing
wells are manifolded together and connected to the vacuum port
of a blower system. Each bioventing well head is equipped with
a valve to control air flow across the treatment zone. The amend-
ment injection wells are manifolded together and connected to
the pressure port of the blower system. An anhydrous ammonia
tank and a methane tank are connected in-line downstream from
the injection port. Ammonia vapor is introduced into the subsur-
face at concentrations well below those considered toxic to mi-
croorganisms. Application frequency and the amounts of nitrogen
added (as ammonia) are periodically adjusted based upon moni-
toring. Methane injection into the soil is limited in order to
prevent excess methane from inhibiting oxidation of the target
contaminants. The methane content measured in the extracted
off-gas and periodic monitoring of methane-degrading microor-
ganisms in the soil are used to determine methane optimum
application rates.
The blower system is equipped with a moisture separating tank.
Moisture collected in the tank is pumped through two water-
Extraction Well Valve
PLOT BOUNDARY
- Off-Gas Extraction Lateral
- Air & Amendment Injection Lateral
Discharge
Figure 1. Schematic of R.E. Wright's In-Situ Bioremediation Treatment
System
phase carbon drums before it is discharged. The blower system
is designed to be fully automated and controlled by a blower unit
timer. Vacuum extraction off-gases are treated with activated
carbon before being exhausted to the atmosphere.
Waste Applicability: According to the Developer, the In-situ
Bioremediation Treatment system is applicable to soils contami-
nated with VOCs and semivolatile compounds, including those
comprising various fuels, hydrocarbons, and solvents. The use
of methane as an easily oxidized cometabolite makes the tech-
nology amenable to treating soils contaminated with halogenated
hydrocarbons.
Demonstration Results: Pilot-scale testing of the In-situ Biore-
mediation Treatment system was conducted at the Sweden-3
Chapman Site in Sweden, New York as part of the Multi-Vendor
Demonstration of Bioremediation Technologies over a -5-month
period between July 1994 to December 1994. The presently
inactive 2-acre landfill was used to dispose of construction and
demolition debris between 1970 and 1975. A state sponsored
investigation of the site conducted between 1985 and 1987 re-
vealed buried drums throughout the landfill. In 1991, over 2,300
drums were removed from the landfill under an interim remedial
measure (IRM). Studies conducted after the drums were re-
moved identified three areas of heavily contaminated soil. The
area referred to as the "Northwestern source area", the focus of
the technology evaluation and the largest of the three areas,
Printed on Recycled Paper
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contained soils contaminated with TCE, PCE, acetone, MEK,
MIBK, toluene, and xylenes.
The In-situ Bioremediation Treatment system constructed at the
site consisted of 3 adjacent plots. Each plot measured 36 feet by
40 feet and consisted of several separately valved rows of ex-
traction and injection wells arranged in an alternating fashion.
Each well is valved independently for optimal system flexibility
and air flow control.
A primary objective of the Demonstration was to determine the
effectiveness of the In-situ Bioremediation Treatment system in
reducing VOC contamination in the soil. Based on this objective,
it was claimed that 90% of the final samples collected from each
plotafter 6 months of continuous operation would be below New
York State Cleanup Objectives for six target VOCs (acetone, 2-
butanone [MEK], 4-methyl-2-pentanone [MIBK], trichloroethene
[TCE], tetrachloroethene [PCE] and 1,2-dichloroethene [DCE]).
The Developer claimed that biodegradation would be the domi-
nant mechanism of contaminant removal. A second objective of
this study was to assess the biological contribution to contami-
nant removal. Additional analytes from the soil, knockout water,
and extracted air streams were collected to further assess perfor-
mance and effectiveness of the technology.
The first primary objective was evaluated by measuring the re-
maining concentrations of the selected VOCs from 9 subplots of
each plot at the completion of the test period. Soil sampling was
conducted initially to determine baseline conditions at the start of
the treatment. Excessive soil moisture and surface water pre-
vented the collection of intermediate samples at the end of 3
months of operation.
The second primary objective, determination of biodegradation
contribution, was estimated by determining the difference be-
tween the initial mass of each VOC in each plot and the sum of
the VOC masses removed in the extracted air stream and
knockout water to the specified time, and that remaining in soil
samples after 6 months. Coupled with other observations and
analyses, the difference between the total mass reduction and
mass reduction by abiotic mechanisms was considered the maxi-
mum mass destroyed by biological processes.
An Innovative Technology Evaluation Report (ITER) describing
the complete demonstration will be available by late 1995.
For Further Information:
EPA Project Manager
Annette Gatchett
U.S. EPA NRMRL
26 W. Martin Luther King Jr. Dr.
Cincinnati, OH 45268
(513) 569-7697
NYSDEC Project Manager
Nick Kolak
NY State Dept. of Environ.
Conservation
Room 208
50 Wolf Rd.
Albany, NY 12233
(518)458-8792
United States
Environmental Protection Agency
National Risk Management Research Laboratory (G-72)
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/540/MR-95/525
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