United States
Environmental Protection
Office of Emergency and
Remedial Response
Washington, DC 20460
Office of
Research and Development
Cincinnati, OH 45268
Superfund
EPA/540/2-90/016
September 1990
Engineering Bulletin
x°/EPA Slurry Biodegradation
Purpose
Section 121(b) of the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maximum
extent practicable" and to prefer remedial actions in which
treatment "permanently and significantly reduces the volume,
toxicity, or mobility of hazardous substances, pollutants and
contaminants as a principal element." The Engineering Bulletins
are a series of documents that summarize the latest information
available on selected treatment and site remediation
technologies and related issues. They provide summaries of
and references for the latest information to help remedial
project managers, on-scene coordinators, contractors, and
other site cleanup managers understand the type of data and
site characteristics needed to evaluate a technology for potential
applicability to their Superfund or other hazardous waste site.
Those documents that describe individual treatment
technologies focus on remedial investigation scoping needs.
Addenda will be issued periodically to update the original
bulletins.
Abstract
In a slurry biodegradation system, an aqueous slurry is
created by combining soil or sludge with water. This slurry is
then biodegraded aerobically using a self-contained reactor or
in a lined lagoon. Thus, slurry biodegradation can be compared
to an activated sludge process or an aerated lagoon, depending
on the case.
Slurry biodegradation is one of the biodegradation methods
for treating high concentrations (up to 250,00 mg/kg) of
soluble organic contaminants in soils and sludges. There are
two main objectives for using this technology: to destroy the
organic contaminant and, equally important, to reduce the
volume of contaminated material. Slurry biodegradation is not
effective in treating inorganics, including heavy metals. This
technology is in developmental stages but appears to be a
promising technology for cost-effective treatment of hazardous
waste.
Slurry biodegradation can be the sole treatment technology
in a complete cleanup system, or it can be used in conjunction
with other biological, chemical, and physical treatment. This
technology was selected as a component of the remedy for
polychlorinatedbiphenyl (PCB)-contaminated oils at the General
Motors Superfund site at Massena, New York, [11, p. 2]* but has
not been a preferred alternative in any record of decision [6, p.
6]. It may be demonstrated in the Superfund Innovative
Technology Evaluation (SITE) program. Commercial-scale
units are in operation. Vendors should be contacted to determine
the availability of a unit for a particular site. This bulletin
provides information on the technology applicability, the types
of residuals produced, the latest performance data, site
requirements, the status of the technology, and sources for
further information.
Technology Applicability
Biodegradation is a process that is considered to have
enormous potential to reduce hazardous contaminants in a
cost-effective manner. Biodegradation is not a feasible treatment
method for all sites. Each vendor's process may be capable of
treating only some contaminants. Treatability tests to determine
the biodegradability of the contaminants and the solids/liquid
separation that occurs at the end of the process are very
important.
Slurry biodegradation has been shown to be effective in
treating highly contaminated soils and sludges that have
contaminant concentrations ranging from 2,500 mg/kg to
250,000 mg/kg. It has the potential to treat a wide range of
organic contaminants such as pesticides, fuels, creosote, penta-
chlorophenol (PCP), PCBs, and some halogenated volatile
organics. It is expected to treat coal tars, refinery wastes,
hydrocarbons, wood-preserving wastes, and organic and
chlorinated organic sludges. The presence of heavy metals and
chlorides may inhibit the microbial metabolism and require
pretreatment. Listed Resource Conservation and Recovery Act
(RCRA) wastes it has treated are shown in Table 1 [10, p. 106].
'[Reference number, page number]
-------
Table 1
RCRA-Listed Hazardous Wastes
Wood Treating Wastes
Dissolved Air Floatation (DAF) Float
Slop Oil Emulsion Solids
K001
K048
K049
American Petroleum Institute (API) Separator
Sludge K051
The effectiveness of this slurry biodegradation on general
contaminant groups for various matrices is shown in Table
2 [12, p. 13]. Examples of constituents within contaminant
groups are provided in Reference 12, "Technology Screening
Guide for Treatment of CERCLA Soils and Sludges." This table
is based on current available information or professional
judgment when no information was available. The proven
effectiveness of the technology for a particular site or waste
does not ensure that it will be effective at all sites or that the
treatment efficiency achieved will be acceptable at other sites.
For the ratings used for this table, demonstrated biodegradability
means that, at some scale, treatability was tested to show that,
for that particular contaminant and matrix, the technology was
effective. The ratings of potential biodegradability and' no
expected biodegradability are based upon expert judgment.
Where potential biodegradability is indicated, the technology
is believed capable of successfully treating the contaminant
group. When the technology is not applicable or will probably
not work for a particular contaminant group, a no-expected-
biodegradability rating is given. Another source of general
observations and average removal efficiencies for different
treatability groups is contained in the Superfund LDR Guide
#6A, "Obtaining a Soil and Debris Treatability Variance for
Remedial Actions," (OSWER Directive 9347.3-06FS [10],, and
Superfund LDR Guide #6B, "Obtaining a Soil and Debris
Treatability Variance for Removal Actions," (OSWER Directive
9347.3-07FS [9].
Limitations
The various characteristics limiting the process feasibility,
the possible reasons for these, and actions to minimize impacts
of these limitations are listed in Table 3 [11, p. 2]. Some of these
actions could be a part of the pretreatment process. The
variation of these characteristics in a particular hardware design,
operation, and/or configuration for a specific site will largely
determine the viability of the technology and cost-effectiveness
of the process as a whole.
Table 2
Degradability Using Slurry Biodegradation
Treatment on General Contaminant Groups for
Soils, Sediments, and Sludges
Contaminant Croups
1
O
•s
Q
0
5
1
«
Halogenated volatiles
Halogenated semivolatiles
Nonhalogenated volatiles
Nonhalogenated semivolatiles
PCBs
Pesticides
Dioxins/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
Oxidizers
Reducers
Biodegradability
All Matrices
T
•
T
T
•
_l
V
3
3
3
J
3
a
T
2
3
• Demonstrated Effectiveness: Successful treatability testat some scale completed
V Potential Effectiveness: Expert opinion that technology will work
G No Expected Effectiveness: Expert opinion that technology will not work
Technology Description
Figure 1 is a schematic of a slurry biodegradation process.
Waste preparation (1) includes excavation and/or moving
the waste material to the process where it is normally screened
to remove debris and large objects. Particle size reduction,
water addition, and pH and temperature adjustment are other
important waste preparation steps that may be required to
achieve the optimum inlet feed characteristics for maximum
contaminant reduction. The desired inlet feed characteristics
[6, p. 14] are:
Organics: .025-25%
Solids: 10-40%
Water: 60-90%
Solids particle size:
by weight
by weight
by weight
Less than 1 /4"
Temperature: 15-35*C
pH: 4.5-8.8
Engineering Bulletin: Slurry Biodegradation Treatment
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After appropriate pretreatment, the wastes are suspended
in a slurry form and mixed in a tank (2) to maximize the mass
transfer rates and contact between contaminants and
microorganisms capable of degrading those contaminants.
Aerobic treatment in batch mode has been the most common
mode of operation. This process can be performed in contained
reactors (3) or in lined lagoons [7, p. 9]. In the latter case,
synthetic liners have to be placed in existing unlined lagoons,
complicating the operation and maintenance of the system. In
this case, excavation of a new lagoon or above-ground tank
reactors should be considered. Aeration is provided by floating
or submerged aerators or by compressors and spargers. Mixing
is provided by aeration alone or by aeration and mechanical
mixing. Nutrients and neutralizing agents are supplied to
relieve any chemical limitations to microbial activity. Other
materials, such as surfactants, dispersants, and compounds
supporting growth and inducing degradation of contaminant
compounds, can be used to improve the materials' handling
characteristics or increase substrate availability for
degradation [8, p. 5]. Microorganisms may be added initially to
seed the bioreactor or added continuously to maintain the
correct concentration of biomass. The residence time in the
bioreactor varies with the soil or sludge matrix; physical/
chemical nature of the contaminant, including concentration;
and the biodegradability of the contaminants. Once
biodegradation of the contaminants is completed, the treated
slurry is sent to a separation/dewatering system (4). A clarifier
for gravity separation, or any standard dewatering equipment,
can be used to separate the solid phase and the aqueous phase
of the slurry.
Site Requirements
Slurry biodegradation tank reactors are generally
transported by trailer. Therefore, adequate access roads are
required to get the unit to the site. Commercial units require a
setup area of 0.5-1 acre per million gallons of reactor volume.
Standard 440V three-phase electrical service is required.
Compressed air must be available. Water needs at the site can
be high if the waste matrix must be made into slurry form.
Contaminated soils or other waste materials are hazardous and
their handling requires that a site safety plan be developed to
provide for personnel protection and special handling measures.
Climate can influence site requirements by necessitating
covers over tanks to protect against heavy rainfall or cold for
long residence times.
Large quantities of wastewaterthat results from dewatering
the slurried soil or that is released from a sludge may need to be
stored prior to discharge to allow time for analytical tests to
verify that the standard for the site has been met. A place to
discharge this wastewater must be available.
Onsite analytical equipment for conducting dissolved
oxygen, ammonia, phosphorus, pH, and microbial activity are
needed for process control. High-performance liquid
chromatographic and/or gas chromatographic equipment is
desirable for monitoring organic biodegradation.
Process Residuals
There are three main waste streams generated in the slurry
biodegradation system: the treated solids (sludge or soil), the
process water, and possible air emissions. The solids are
dewatered and may be further treated if they still contain
organic contaminants. If the solids are contaminated with
inorganics and/or heavy metals, they can be stabilized before
disposal. The process water can be treated in an onsite
treatment system prior to discharge, or some of it (as high as 90
percent by weight of solids) is usually recycled to the front end
of the system for slurrying. Air emissions are possible during
operation of the system (e.g., benzene, toluene, xylene [BTX]
compounds); hence, depending on the waste characteristics,
air pollution control, such as activated carbon, may be necessary
[4, p. 29].
Performance Data
Performance results on slurry biodegradation systems are
provided based on the information supplied by various vendors.
The quality assurance for these results has not been evaluated.
In most of the performances, the cleanup criteria were based on
the requirements of the client; therefore, the data do not
necessarily reflect the maximum degree of treatment possible.
Remediation Technologies, Inc.'s (ReTeC) full-scale slurry
biodegradation system (using a lined lagoon) was used to treat
wood preserving sludges (K0001) at a site in Sweetwater,
Tennessee, and met the closure criteria for treatment of these
sludges. The system achieved greater than 99 percent removal
efficiency and over 99 percent reduction in volume attained for
PCP and polynuclear aromatic hydrocarbons (PAHs) (Table 4
and Table 5).
Engineering Bulletin: Slurry Biodegradation Treatment
-------
Figure 1
Slurry Biodegradation Process
I
Wa<
Prepar
(1
Si-Hi 1 Soil *-
> |
Water
^,
^
Nutrients/
Additives
L
Mixing Tank
(2)
Slurry
Oxygen
— ^^
t
L
Bio Reactors
(3)
Slurry
Emissk
Contr
\
Dns
ol
Dewatering
(4)
^—
^ Treated
^ tmissions
^ Water
Solids
Oversized
Rejects
Table 3
Characteristics Limiting the Slurry Biodegradation Process
CHARACTERISTICS LIMITING
THE PROCESS FEASIBILITY
Variable waste composition
Nonuniform particle size
Water solubility
Biodegradability
Temperature outside 1 5-35°C
range
Nutrient deficiency
Oxygen deficiency
Insufficient Mixing
pH outside 4.5 - 8.8 range
Microbial population
Water and air emissions
discharges
Presence of elevated, dissolved
levels of:
• Heavy metals
• Highly chlorinated organics
• Some pesticides, herbicides
• Inorganic salts
REASONS FOR POTENTIAL IMPACT
Inconsistent biodegradation caused by
variation in biological activity
Minimize the contact with microorganisms
Contaminants with low solubility are
harder to biodegrade
Low rate of destruction inhibits process
Less microbial activity outside this range
Lack of adequate nutrients for biological
activity
Lack of oxygen is rate limiting
Inadequate microbes/solids/organics
contact
Inhibition of biological activity
Insufficient population results in low
biodegradation rates
Potential environmental and/or health
impacts
Can be highly toxic to microorganisms
ACTIONS TO MINIMIZE IMPACTS
Dilution of waste stream. Increase mixing
Physical separation
Addition of surfactants or other emulsifiers
Addition of microbial culture capable of
degrading particularly difficult compounds or
longer residence time
Temperature monitoring and adjustments
Nutrient monitoring; adjustment of the
carbon/nitrogen/phosphorus ratio
Oxygen monitoring and adjustments
Optimize mixing characteristics
Sludge pH monitoring. Addition of acidic or
alkaline compounds
Culture test, addition of culture strains
Post-treatment processes (e.g., air scrubbing,
carbon filtration)
Pretreatment processes to reduce the
concentration of toxic compounds in the
constituents in the reactor to nontoxic range
Engineering Bulletin: Slurry Biodegradation Treatment
-------
Table 4
Results Showing Reduction in Concentration for Wood Preserving Wastes
Compounds
Phenol
Pentachlorophenol
Naphthalene
Phenanthrene & Anthracene
Fluoranthene
Carbazole
Initital Concentration
Solids Slurry
(mg/kg) (mg/kg)
14.6
687
3,670
30,700
5,470
1,490
1.4
64
343
2,870
511
139
*May be due to combined effect of Volatilization and Biodegradation.
Final Concentration
Solids
(mg/kg)
0.7
12.3
23
200
67
4.9
Slurry
(mg/kg)
<0.1
0.8
1.6
13.7
4.6
0.3
Percent Removal
Solids Slurry
(mg/kg) (mg/kg)
95.2*
98.2
99.3*
99.3
98.8
99.7
92.8
92.8
99.5*
99.5
99.1
99.8
[Source: ReTec, 50,000 gal. reactor]
Table 5
Results Showing Reduction in Volume For Wood Preserving Wastes
Compounds
Phenol
Pentachlorophenol
Naphthalene
Phenanthrene & Anthracene
Fluoranthene
Carbazole
Before Treatment
(Total pounds)
368
141,650
1 79,830
2,018,060
190,440
114,260
*May be due to combined effect of Volatilization and Biodegradation.
After Treatment
(Total pounds)
41.4
193.0
36.6
303.1
341.7
93.7
[Source: ReTec, 50,000 gal. reactor]
Percent Volume
Reduction
88.8*
99.9
99.9*
99.9
99.8
99.9
Data for one of these pilot-scale field demonstrations,
which treated 72,000 gallons of oil refinery sludges, are shown
in Figure 2 [8, p. 24]. In this study, the degradation of PAHs was
relatively rapid and varied depending on the nature of the
waste and loading rate. The losses of carcinogenic PAHs
(principally the 5- and 6-ring PAHs) ranged from 30 to 80
percent over 2 months while virtually all of the noncarcinogenic
PAHs were degraded. The total PAH reduction ranged from 70
to 95 percent with a reactor residence time of 60 days.
ECOVA's full-scale, mobile slurry biodegradation unit was
used to treat more than 750 cubic yards of soil contaminated
with 2,4-Dichlorophenoxy acetic acid (2,4-D) and 4-chloro-2-
methyl-phenoxyacetic acid (MCPA) and other pesticides such
as alachlor, trifluralin, and carbofuran. To reduce 2,4-D and
MCPA levels from 800 ppm in soil and 400 ppm in slurry to less
than 20 ppm for both in 1 3 days, 26,000-gallon bioreactors
capable of handling approximately 60 cubic yards of soil were
used. The residuals of the process were further treated through
land application [3, p. 4]. Field application of the slurry bio-
degradation system designed by ECOVA to treat PCP-
contaminated wastes has resulted in a 99-percent decrease in
PCP concentrations (both in solid and aqueous phase) over a
period of 24 days [3, p. 5].
Performance data for Environmental Remediation, Inc.
(ERI) is available for the treatment of American Petroleum
Institute (API) separator sludge and wood-processing wastes.
Two lagoons containing an olefin sludge from an API separator
were treated. In one lagoon, containing, 4,000 cubic yards of
sludge, a degradation time of 21 days was required to achieve
68 percent volume reduction and 62 percent mass oil and
grease reduction at an operating temperature of 18°C. In the
second lagoon, containing 2,590 cubic yards of sludge, a
treatment time of 61 days was required to achieve 61 percent
sludge reduction and 87.3 percent mass oil and grease reduction
at an operating temperature of 14°C [1, p. 367].
At another site, the total wood-preserving constituents
were reduced to less than 50 ppm. Each batch process was
Engineering Bulletin: Slurry Biodegradation Treatment
-------
Figure 2
Pilot Scale Results on Oil Refinery Sludges
1500 _/
1000 -
[J Non Care. PAH
• Care. PAH
500 —
[Source: ReTeC]
Days:
% Solids:
Sample:
0 60
5%
0 60
10%
Lagoon
Sludge
0 60
5%
0 60
30%
Pit
Sludge
carried out with a residence time of 28 days in 24 foot-
diameter, 20-foot-height tank reactors handling 40 cubic yards
per batch [6]. The mean concentrations of K001 constituents
before treatment and the corresponding concentrations after
treatment, for both settled solids and supernatant, are provided
in Table 6 [2, p. 11 ]. The supernatant was discharged to a local,
publicly owned wastewater treatment works.
RCRA Land Disposal Restrictions (LDRs) that require
treatment of wastes to best demonstrated available technology
(BOAT) levels prior to land disposal may sometimes be
determined to be applicable or relevant and appropriate
requirements (ARARs) for CERCLA response actions. Slurry
biodegradation can produce a treated waste that meets
treatment levels set by BOAT, but may not reach these treatment
levels in all cases. The ability to meet required treatment levels
is dependent upon the specific waste constituents and the
waste matrix. In cases where slurry biodegradaton does not
meet these levels, it still may, in certain situations, be selected
for use at the site if a treatability variance establishing alternative
treatment levels is obtained. EPA has made the treatability
variance process available in order to ensure that LDRs do not
unnecessarily restrict the use of alternative and innovative
treatment technologies. Treatability variances may be
justified for handling complex soil and debris matrices. The
following guides describe when and how to seek a treatability
variance for soil and debris: Superfund LDR Guide #6A,
"Obtaining a Soil and Debris Treatability Variance for Remedial
Actions," (OSWER Directive 9347.3-06FS) [10] and Superfund
LDR Guide #6B, "Obtaining a Soil and Debris Treatability
Variance for Removal Actions" (OSWER Directive 9347.3-07FS)
[9]. Another approach could be to use other treatment
techniques in series with slurry biodegradation to obtain desired
treatment levels.
Technology Status
Biotrol, Inc. has a pilot-scale slurry bioreactor that consists
of a feed storage tank, a reactor tank, and a dewatering system
for the treated slurry. It was designed to treat the fine-particle
slurry from its soil-washing system. Biotrol's process was
included in the SITE program demonstration of its soil-washing
system at the MacGillis and Gibbs wood-preserving site in New
Brighton, Minnesota, during September and October of 1989.
Performance data from the SITE demonstration are not currently
available; the Demonstration and Applications Analysis Report
is scheduled to be published in latel 990.
Engineering Bulletin: Slurry Biodegradation Treatment
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Table 6
Results of Wood Preserving Waste Treatment
Wood Preserving Waste
Constituents
2-Chlorophenol
Phenol
2,4-Dimethylphenol
2,4,6-Trichlorophenol
p-Chloro-m-cresol
Tetrachlorophenol
2,4-Dinitrophenol
Pentachlorophenol
Naphthalene
Acenaphthylene
Phenanthrene + Anthracene
Fluoranthene
Chrysene + Benz(a)anthracene
Benzo(b)fluoranthene
Benzo(a)pyrene
lndeno(1,2,3-cd)pyrene +
Dibenz(a,h)anthracene
Carbazole
Before treatment
In Soil
(mg/kg)
1.89
:$.9i
7.73
6.99
118.62
11.07
4.77
420.59
1078.55
998.80
6832.07
1543.06
519.32
519.32
82.96
84.88
135.40
After Treatment
In Settled Soil
(mg/kg)
<0.01
<0.01
<0.01
<0.01
<0.01
<0.02
<0.03
3.1
<0.01
1.4
3.8
4.9
1.4
<0.03
0.1
0.5
<0.05
In Supernatant
(mg/L)
<0.01
<0.01
<0.01
<0.01
<0.01
<0.02
<0.03
<0.01
0.04
1.60
3.00
16.00
8.20
4.50
2.50
1.70
1.70
[Source: Environmental Solutions, Inc.]
ECOVA Corporation has a full-scale mobile slurry
biodegradation system. This system was demonstrated in the
field on soils contaminated with pesticides and PCP. ECOVA
has developed an innovative treatment approach that utilizes
contaminated ground water on site as the make up water to
prepare the slurry for the bioreactor.
ERI has developed a full-scale slurry biodegradation system.
ERI's slurry biodegradation system was used to reduce sludge
volumes and oil and grease content in two wastewater treatment
lagoons at a major refinery outside of Houston, Texas, and to
treat 3,000 cubic yards of wood-preserving waste (creosote-
K001) over a total cleanup time of 18 months.
Environmental Solutions, Inc. reportedly has a full-scale
slurry biodegradation system, with a treatment capacity of up
to 100,000 cubic yards, that has been used to treat petroleum
and hydrocarbon sludges.
Groundwater Technology, Inc. reportedly has a full-scale
slurry biodegradation system, which employs flotation, reactor,
and clarifier/sedimentation tanks in series, that has been used
to treat soils contaminated with heavy oils, PAHs, and light
organics.
ReTeC's full-scale slurry biodegradation system was used
in two major projects: Valdosta, Georgia, and Sweetwater,
Tennessee. Both projects involved closure of RCRA-regulated
surface impoundments containing soils and sludges
contaminated with creosote constituents and PCP. Each project
used in-ground, lined slurry-phase bioreactor cells operating at
100 cubic yards per week. Residues were chemically stabilized
and furthertreated by tillage. Forfinal closure, the impoundment
areas and slurry-phase cells were capped with clay and a heavy-
duty asphalt paving [5]. ReTeC has also performed several pilot-
scale field demonstrations with their system on oil refinery
sludges (RCRA K048-51).
One vendor estimates the cost of full-scale operation to be
$80 to $150 per cubic yard of soil or sludge, depending on the
initial concentration and treatment volume. The cost to use
slurry biodegradation will vary depending upon the need for
additional pre- and post-treatment and the addition of air
emission control equipment.
EPA Contact
Technology-specific questions regarding slurry bio-
degradation may be directed to:
Dr. Ronald Lewis
U.S. EPA Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, Ohio 45268
Telephone: FTS 684-7856 or (51 3) 569-7856.
Engineering Bulletin: Slurry Biodegradation Treatment
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REFERENCES
6.
Christiansen, J., T. Koenig, and G. Lucas. Topic 3:
Liquid/Solids Contact Case Study. In: Proceedings
from the Superfund Conference, Environmental
Remediation, Inc., Washington, D.C., 1989. pp. 365-
374.
Christiansen, j., B. Irwin, E. Titcomb, and S. Morris.
Protocol Development For The Biological Remediation
of A Wood-Treating Site. In: Proceedings from the 1 st
International Conference on Physicochemical and
Biological Detoxification and Biological Detoxification
of Hazardous Wastes, Atlantic City, New jersey, 1989.
ECOVA Corporation. Company Project Description,
(no date).
Kabrick, R., D. Sherman, M. Coover, and R. Loehr.
September 1989, Biological Treatment of Petroleum
Refinery Sludges. Presented at the Third International
Conference on New Frontiers for Hazardous Waste
Management, Remediation Technologies, Inc.,
Pittsburgh, Pennsylvania, 1989.
ReTeC Corporation. Closure of Creosote and
Pentachlorophenol Impoundments. Company
Literature, (no date).
Richards, D. j. Remedy Selection at Superfund Sites on
Analysis of Bioremediation, 1989 AAAS/EPA
Environmental Science and Engineering Fellow, 1989.
10.
11
12.
Stroo, H. F., Remediation Technologies Inc. Biological
Treatment of Petroleum Sludges in Liquid/Solid
Contact Reactors. Environmental and Waste
Management World 3 (9): 9-12, 1989.
Stroo, H.F., J. Smith, M. Torpy, M. Coover, and R.
Kabrick. Bioremediation of Hydrocarbon-
Contaminated/Solids Using Liquid/Solids Contact
Reactors, Company Report, Remediation Technologies,
Inc., (no date), 27 pp.
Superfund LDR Guide #6B: Obtaining a Soil and Debris
Treatability Variance for Removal Actions. OSWER
Directive 9347.3-07FS, U.S. Environmental Protection
Agency, 1989.
Superfund LDR Guide #6A: Obtaining a Soil and
Debris Treatability Variance for Remedial Actions.
OSWER Directive 9347.3-06FS, U.S. Environmental
Protection Agency, 1989.
Innovative Technology: Slurry-Phase Biodegradation.
OSWER Directive 9200.5-252FS, U.S. Environmental
Protection Agency, 1989.
Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/004, U.S.
Environmental Protection Agency, 1988.
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati, OH 45268
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