v>EPA
Environmental Protection
Agency
Office of Emergency and
Remedial Response
Washington, DC 20460
Office of
Research and Development
Cincinnati, OH 45268
Superfund
EPA/540/2-90/017
September 1990
Engineering Bulletin
Soil Washing Treatment
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
Soil washing is a water-based process for mechanically
scrubbing soils ex-situ to remove undesirable contaminants.
The process removes contaminants from soils in one of two
ways: by dissolving or suspending them in the wash solution
(which is later treated by conventional wastewater treatment
methods) or by concentrating them into a smaller volume of
soil through simple particle size separation techniques (similar
to those used in sand and gravel operations). Soil washing
systems incorporating both removal techniques offer the greatest
promise for application to soils contaminated with a wide
variety of heavy metal and organic contaminants.
The concept of reducing soil contamination through the
use of particle size separation is based on the finding that most
organic and inorganic contaminants tend to bind, either
chemically or physically, to clay and silt soil particles. The silt
and clay, in turn, are attached to sand and gravel particles by
physical processes, primarily compaction and adhesion.
Washing processes that separate the fine (small) clay and silt
particles from the coarser sand and gravel soil particles effectively
separate and concentrate the contaminants into a smaller
volume of soil that can be further treated or disposed. The
clean, larger fraction can be returned to the site for continued
use. This set of assumptions forms the basis for the volume-
reduction concept upon which most soil washing technology
applications are being developed.
At the present time, soil washing is used extensively in
Europe and has had limited use in the United States. During
1986-1989, the technology was one of the selected source
control remedies at eight Superfund sites.
The final determination of the lowest cost alternative will
be more site-specific than process equipment dominated.
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 resulting
from the use of the technology, the latest performance data,
site requirements, the status of the technology, and where to
go for further information.
Technology Applicability
Soil washing can be used either as a stand-alone technology
or in combination with other treatment technologies. In some
cases, the process can deliver the performance needed to
reduce contaminant concentrations to acceptable levels and,
thus, serve as a stand-alone technology. In other cases, soil
washing is most successful when combined with other
technologies. It can be cost-effective as a pre-processing step
in reducing the quantity of material to be processed by another
technology such as incineration; it also can be used effectively
to transform the soil feedstock into a more homogeneous
condition to augment operations in the subsequent treatment
system. In general, soil washing is effective on coarse sand and
gravel contaminated with a wide range of organic, inorganic,
and reactive contaminants. Soils containing a large amount of
clay and silt typically do not respond well to soil washing,
especially if it is applied as a stand-alone technology.
A wide variety of chemical contaminants can be removed
from soils through soil washing applications. Removal efficiencies
depend on the type of contaminant as well as the type of soil.
Volatile organic contaminants often are easily removed from
soil by washing; experience shows that volatiles can be removed
with 90-99 percent efficiency or more. Semivolatile organics
-------
may be removed to a lesser extent (40-90 percent) by selection
of the proper surfactant. Metals and pesticides, which are more
insoluble in water, often require acids or chelating agents for
successful soil washing. The process can be applicable for the
treatment of soils contaminated with specific listed Resource
Conservation and Recovey Act (RCRA) wastes and other
hazardous wastes including wood-preserving chemicals
(pentachlorophenol, creosote), organic solvents, electroplating
residues (cyanides, heavy metals), paint sludges (heavy metals),
organic chemicals production residues, pesticides and pesticides
production residues, and petroleum/oil residues [1, p. 659][2,
p. 15][4][7 through 13]*.
The effectiveness of soil washing for general contaminant
groups and soil types is shown in Table 1 [1, p. 659][3, p.
13][15, p.1]. Examples of constituents within contaminant
groups are provided in Reference 3, "Technology Screening
Guide For Treatment of CERCLA Soils and Sludges." This table
is based on currently available information or professional
judgment where definitive information is currently inadequate
or unavailable. 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 in this table, good
to excellent applicability means the probability is high that soil
Table 1
Applicability of Soil Washing on General Contaminant
Groups for Various Soils
Contaminant Croups
^
i>
6
^
1
1
"~
u
«
Halogenated volatiles
Halogenated semivolatiles
Nonhalogenated volatiles
Nonhalogenated semivolatiles
PCBs
Pesticides (halogenated)
Dioxins/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
Oxidizers
Reducers
Matrix
Sandy/ Silty/Clay
Gravelly Soils Soils
•
V
•
T
T
T
V
T
V
•
•
a
V
T
V
T
V
V
T
V
T
V
V
V
V
T
T
T
a
T
T
V
T
V
• Good to Excellent Applicability: High probability that technology will be
successful
T Moderate to Marginal Applicability: Exercise care in choosing technology
Q Not Applicable: Expert opinion that technology will not work
washing will be effective for that particular contaminant and
matrix. Moderate to marginal applicability indicates situations
where care needs to be exercised in choosing the soil washing
technology. When not applicable is shown, the technology will
probably not workforthatparticularcombination of contaminant
group and matrix. Other sources of general observations and
average removal efficiencies for different treatability groups are
the Superfund LDR Guide #6A, "Obtaining a Soil and Debris
Treatability Variance for Remedial Actions" (OSWER Directive
9347.3-06FS), [16] and Superfund LDR Guide #6B, "Obtaining
a Soil and Debris Treatability Variance for Removal Actions"
(OSWER Directive 9347.3-07FS) [17].
Information on cleanup objectives as well as the physical
and chemical characteristics of the site soil and its contaminants
is necessary to determine the potential performance of this
technology and the requirements for waste preparation and
pretreatment. Treatability tests are also required at the laboratory
screening, bench-scale and/or pilot-scale level(s) to determine
Table 2
Waste Soil Characterization Parameters
* [reference number, page number]
Parameter
Key Physical
Particle size distribution:
>2 mm
0.25-2 mm
0.063-0.25 mm
<0.063 mm
Other Physical
Type, physical form,
handling properties
Moisture content
Key Chemical
Organics
Concentration
Volatility
Partition
coefficient
Purpose and Comment
Oversize pretreatment requirements
Effective soil washing
Limited soil washing
Clay and silt fraction—difficult soil
washing
Affects pretreatment and transfer
requirements
Affects pretreatment and transfer
requirements
Metals
Humic acid
Other Chemical
pH, buffering
capacity
Determine contaminants and assess
separation and washing efficiency,
hydrophobic interaction, washing
fluid compatibility, changes in
washing fluid with changes in
contaminants. May require
preblending for consistent feed. Use
the jar test protocol to determine
contaminant partitioning.
Concentration and species of
constituents (specific jar test) will
determine washing fluid compatibility,
mobility of metals, posttreatment.
Organic content will affect adsorption
characteristics of contaminants on soil.
Important in marine/wetland sites.
May affect pretreatment
requirements, compatibility with
equipment materials of construction,
wash fluid compatibility.
Engineering Bulletin: Soil Washing Treatment
-------
Figure 1
Soil Washing Applicable Particle Size Range
Gravel
, Average ( Large
Sand
Average • Large
Soil Washing
(Regime III)
Soil Wash with
Specific Washing Fluid
(Regime II)
Economic Wash
with Simple Particle
Size Separation
(Regime I)
0.001 0.002 0.006 0.01 0.02
0.063 0.1 0.2 0.6 1 2
Diameter of Particle in Millimeters
10 20
60 100
the feasibility of the specific soil washing process being
considered and to understand waste preparation and
pretreatment steps needed at a particular site. If bench-test
results are promising, pilot-scale demonstrations should normally
be conducted before final commitment to full-scale
implementation. Treatability study procedures are explained
in the EPA's forthcoming document entitled "Superfund
Treatability Study Protocol: Bench-Scale Level of Soils Washing
for Contaminated Soils" [14].
Table 2 contains physical and chemical soil characterization
parameters that must be established before a treatability test is
conducted on a specific soil washing process. The parameters
are defined as either "key" or "other" and should be evaluated
on a site-specific basis. Key parameters represent soil
characteristics that have a direct impact on the soil washing
process. Other parameters should also be determined, but they
can be adjusted prior to the soil washing step based on specific
process requirements. The table contains comments relating to
the purpose of the specific parameter to be characterized and
its impact on the process [6, p. 90][14, p. 35].
Particle size distribution is the key physical parameter for
determining the feasibility of using a soil washing process.
Although particle size distribution should not become the sole
reason for choosing or eliminating soil washing as a candidate
technology for remediation, it can provide an initial means of
screening for the potential use of soil washing. Figure 1
presents a simplistic particle size distribution range of curves
that illustrate a general screening definition for soil washing
technology.
In its simplest application, soil washing is a particle size
separation process that can be used to segregate the fine
fractions from the coarse fractions. In Regime I of Figure 1,
where coarse soils are found, the matrix is very amenable to soil
washing using simple particle size separation.
Most contaminated soils will have a distribution that falls
within Regime II of Figure 1. The types of contaminants found
in the matrix will govern the composition of the washing fluid
and the overall efficiency of the soil washing process.
In Regime III of Figure 1, soils consisting largely of finer
sand, silt, and clay fractions, and those with high humic
content, tend to contain strongly adsorbed organics that
generally do not respond favorably to systems that work by only
dissolving or suspending contaminants in the wash solution.
However, they may respond to soil washing systems that also
incorporate a particle size separation step whereby contaminants
can be concentrated into a smaller volume.
Limitations
Contaminants in soils containing a high percentage of silt-
and clay-sized particles typically are strongly adsorbed and
difficult to remove. In such cases, soil washing generally should
not be considered as a stand-alone technology.
Hydrophobic contaminants generally require surfactants
or organic solvents for their removal from soil. Complex
mixtures of contaminants in the soil (such as a mixture of
metals, nonvolatile organics, and semivolatile organics) and
Engineering Bulletin: Soil Washing Treatment
-------
Figure 2
Aqueous Soil Washing Process
Volatile:
Contaminated
Soil
Makeup water
Extracting Agent(s)
(Surfactants, etc.)
Soil
Preparation
(1)
Prepared
Soil
Soil Washing
Process
(2)
-Washing
-Rinsing
-Size Separation
I
Emission
Control
Treated
Air Emissions
Recycled water
Chemicals
Slowdown
Water
1
Wastewater
Treatment
(3)
Treated
Water
Sludges/
Contaminated Fines
Clean Soil
Oversized Rejects
frequent changes in the contaminant composition in the soil
matrix make it difficult to formulate a single suitable washing
fluid that will consistently and reliably remove all of the different
types of contaminants from the soil particles. Sequential
washing steps may be needed. Frequent changes in the wash
formulation and/or the soil/wash fluid ratio may be required [3,
p. 76][14, p. 7].
While washwater additives such as surfactants and chelants
may enhance some contaminant removal efficiencies in the soil
washing portion of the process, they also tend to interfere with
the downstream wastewater treatment segments of the process.
The presence of these additives in the washed soil and in the
wastewater treatment sludge may cause some difficulty in their
disposal [14, p. 7][15, p. 1 ]. Costs associated with handling the
additives and managing them as part of the residuals/wastewater
streams must be carefully weighed against the incremental
improvements in soil washing performance that they may
provide.
Technology Description
Figure 2 is a general schematic of the soil washing process
[1,p.657][3,p.72][15,p.1].
Soil preparation (1) includes the excavation and/or moving
of contaminated soil to the process where it is normally
screened to remove debris and targe objects. Depending upon
the technology and whether the process is semibatch or
continuous, the soil may be made pumpable by the addition of
water.
A number of unit processes occur in the soil washing
process(2). Soil ismixed with washwater and possibly extraction
agent(s) to remove contaminants from soil and transfer them
to the extraction fluid. The soil and washwater are then
separated, and the soil is rinsed with clean water. Clean soil is
then removed from the process as product. Suspended soil
particles are recovered directly from the spent washwater, as
sludge, by gravity means, or they may be removed byflocculation
with a selected polymer or chemical, and then separated by
gravity. These solids will most likely be a smaller quantity but
carry higher levels of contamination than the original soil and,
therefore, should be targeted for either further treatment or
secure disposal. Residual solids from recycle water cleanup may
require post-treatment to ensure safe disposal or release. Water
used in the soil washing process is treated by conventional
wastewater treatment processes to enable it to be recycled for
further use.
Engineering Bulletin: Soil Washing Treatment
-------
Wastewater treatment (3) processes the blowdown or
discharge water to meet regulatory requirements for heavy
metal content, organics, total suspended solids, and other
parameters. Whenever possible, treated water should be
recycled to the soil washing process. Residual solids, such as
spent ion exchange resin and carbon, and sludges from biologi-
cal treatment may require post-treatment to ensure safe disposal
or release.
Vapor treatment may be needed to control air emissions
from excavation, feed preparation, and extraction; these
emissions are collected and treated, normally by carbon
adsorption or incineration, before being released to the
atmosphere.
Process Residuals
There are four main waste streams generated during soil
washing: contaminated solids from the soil washing unit,
wastewater, wastewater treatment sludges and residuals, and
air emissions.
Contaminated clay fines and sludges resulting from the
process may require further treatment using acceptable
treatment technologies (such as incineration, low temperature
desorption, solidification and stabilization, biological treatment,
and chemical treatment) in order to permit disposal in an
environmentally safe manner [16]. Blowdown water may need
treatment to meet appropriate discharge standards prior to
release to a local, publicly owned wastewater treatment works
or receiving stream. To the maximum extent practical, this
water should be recovered and reused in the washing process.
The wastewater treatment process sludges and residual solids,
such as spent carbon and spent ion exchange resin, must be
appropriately treated before disposal. Any air emissions from
the waste preparation area or the washing unit should be
collected and treated, as appropriate to meet applicable
regulatory standards.
Site Requirements
Access roads are required for transport of vehicles to and
from the site. Typically, mobile soil washing process systems
are located onsite and may occupy up to 4 acres for a 20 ton/
hour unit; the exact area will depend on the vendor system
selected, the amount of soil storage space, and/or the number
of tanks or ponds needed for washwater preparation and
wastewater treatment.
Typical utilities required are water, electricity, steam, and
compressed air. An estimate of the net (consumed) quantity of
local water required for soil washing, assuming water cleanup
and recirculation, is 130,000-800,000 gallons per 1,000 cubic
yards (2,500,000 Ibs.) of soil (approximately 0.05-0.3 gallons
per pound).
Because contaminated soils are usually considered
hazardous, their handling requires that a site safety plan be
developed to provide for personnel protection and special
handling measures during soil washing operations.
Moisture content of soil must be controlled for consistent
handling and treatment; this can be accomplished, in part, by
covering excavation, storage, and treatment areas.
Fire hazard and explosion considerations should be minimal,
since the soil washing fluid is predominantly water. Generally,
soil washing does not require storing explosive, highly reactive
materials.
Climatic conditions such as annual or seasonal precipitation
cause surface runoff and water infiltration. Berms, dikes, or
other runoff control methods may be required. Cold weather
freezing must also be considered for aqueous systems and soil
excavation operations.
Proximity to a residential neighborhood will affect plant
noise requirements and emissions permitted in order to minimize
their impact on the population and meet existing rules and
regulations.
If all or part of the processed soil is to be redeposited at the
site, storage areas must be provided until analytical data are
obtained that verifies that treatment standards have been
achieved. Onsite analytical capability could expedite the
storage/final disposition process. However, soil washing might
be applied to many different contaminant groups. Therefore,
the analytes that would have to be determined are site specific,
and the analytical equipment that must be available will vary
from site to site.
Performance Data
The performances of soil washing processes currently
shown to be effective in specific applications are listed in Table
3 [1 ][2][4][7 through 13]. Also listed are the range of particle
size treated, contaminants successfully extracted, byproduct
wastes generated, extraction agents used, major extraction
equipment for each system, and general process comments.
The data presented for specific contaminant removal
effectiveness were obtained from publications developed by
the respective soil washing system vendors. The quality of this
information has not been determined.
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. The soil
washing technology 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 soil washing 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
Engineering Bulletin: Soil Washing Treatment
-------
and DebrisTreatability Variance for Remedial Actions" (OSWER
Directive 9347.3-06FS) [16], and Superfund LDR Guide #6B,
"Obtaining a Soil and Debris Treatability Variance for Removal
Actions" (OSWER Directive 9347.3-07FS) [17]. Another
approach could be to use other treatment techniques in series
with soil washing to obtain desired treatment levels.
Technology Status
During 1986-1989, soil washing technology was selected
as one of the source control remedies at eight Superfund sites:
Vineland Chemical, New Jersey; Koppers Oroville Plant,
California; Cape Fear Wood Preserving, North Carolina; Ewan
Property, New Jersey; Tinkam Garage, New Hampshire; United
Scrap, Ohio; Koppers/Texarkana, Texas; and South Cavalcade,
Texas [18].
A large number of vendors provide a soil washing
technology. Table 3 shows the current status of the technology
for 14 vendors. Thef ront portion of the table indicates the scale
of equipment available from the vendor and gives some
indication of the vendor's experience by showing the year it
began operation.
Processes evaluated or used for site cleanups by the EPA are
identified separately by asterisks in the Proprietary Vendor
Process/EPA column in Table 3.
The following soil washing processes that are under
development have not been evaluated by the EPA or included
in Table 3. Environmental Group, Inc. of Webster, Texas, has
a process that reportedly removes metals and oil from soil.
Process efficiency is stated as greater than 99 percent for lead
removal from soils cleaned in Concord, California; greater than
99 percent for copper, lead, and zinc at a site in Racine,
Wisconsin; and 94 percent for PCB removal on a Morrison-
Knudsen Company project. The process does not appear to
separate soil into different size fractions. Detailed information
on the process is not available. Consolidated Sludge Company
of Cleveland, Ohio, has a soil washing system planned that
incorporates their Mega-sludge Press at the end of the process
for dewatering solids. The system has not yet been built.
Vendor-supplied treatment costs of the processes reviewed
ranged from $50 to $205 per ton of feed soil. The upper end
of the cost range includes costs for soil residue disposal.
EPA Contact
Technology-specific questions regarding soil washing may
be directed to:
Michael Gruenfeld
U.S. EPA, Releases Control Branch
Risk Reduction Engineering Laboratory
Woodbridge Avenue, Building 10
Edison, New Jersey 08837
Telephone FTS 340-6625 or (201) 321-6625.
Engineering Bulletin: Soil VM
Treatment
-------
Table 3. Summary of Performance Data and Technology Status - Part I
Proprietary Vendor
Process/EPA
Highest Scale
of Operation
Year Operation
Began
Range of Particle
Size Treated
Contaminants
Extracted From Soil
Extraction Agent(s)
U.S. Processes
(1) SOIL CLEANING COMPANY
OF AMERICA [5][1 5, p. 2]
(2)* BIOTROLSOILTREATMENT
SYSTEM (BSTS)
Kp.6][12]
(3) ERA'S MOBILE COUNTER-
CURRENT EXTRACTOR
[9][5, p. 5]
(4)* ERA'S FIRST GENERATION
PILOT DRUM SCREEN
WASHER [10, p. 8]
(5)* MTA REMEDIAL
RESOURCES
[11][15,p.2]
Full scale
15tons/hr
Pilot scale
500 Ibs/hr
Pilot scale
4.1 tons/hr
Pilot scale
Bench scale
1988
Fall, 1987
Modified with
drum washer
and shakedown-
1982
Full Scale-1 986
1988
N/A
Bulk soil
Above clay size and
below 0.5 in. Some
cleaning of fine par-
ticles in bio-reactor
2-25 mm in drum
washer
<2 mm in four-stage
extractor
Oversize (>2 mm)
removed prior to
treatment
Oversize removed
prior to treatment
Oil and grease
Organics - pentachloro-
phenol, creosote,
naphthalene, pyrene,
fluorene, etc.
Soluble organics
(phenol, etc.)
Heavy metals
(Pb, etc.)
Petroleum
hydrocarbons
Organics (oil)
Heavy metals (inorganics]
removed using counter-
current decantation
with leaching
Hot water with
surfactant
Proprietary
conditioning
chemicals
Various solvents,
additives, surfactants,
redox acids and bases
Chelating agent
(EDTA)
Biodegradable
surfactant
(aqueous slurry)
Surfactants and
alkaline chemicals
added upstream of
froth flotation cells.
Acid for leaching.
Non-U.S. Processes
(6) ECOTECHNIEK BV
[2, p. 17]
(7) BODEMSANERING
NEDERLAND
BV (BSN)
[2, p. 17]
(8) HARBAUER
[2, p. 20][7, p. 5]
(9) HWZ
BODEMSANERING BV
[2, p. 17]
(10) HEIJMAN
MILIEUTECHNIEK BV
[2,p.17][7,p.6]
(11) HEIDEMI] FROTH
FLOTATION
[7, p. 8]
Commercial
100 ton/hr max
Commercial
20 ton/hr
Commercial
15-20tonS/hr
Commercial
20-25 tons/hr
Pilot scale
10-1 5 tons/hr
Full scale
1982
1982
Lab -1985
Commercial -1 986
With fines
removal - 1 987
1984
1985
N/A
Sandy soil
>1 00 mm removed
No more than 20%
<63jim
Sludge <30 jim not
cleaned
1 5 urn - 5mm Pre-
treatmcnt: coarse
screens, electromagnet
blade washer
<10 mm and >63 jim
<1 0 mm and no more
than 30% <63 urn
<4 mm and no more
than 20% <50 urn
Crude oil
Oil from sandy soil
Mostly organics
Limited heavy metals
removal experience
Cyanide, Chlorinated
HC, some heavy
metals, PNA
Cyanide, heavy metals,
mineral oil (water
immiscible hydro-
carbons)
Cyanide, heavy metals,
chlorinated HCs, oil,
toluene, benzene,
pesticides, etc.
None. Water-sand
slurry heated to 90°C
max^with steam.
^f
None. Uses high
pressure water jet
for soils washing.
Hydraulically
produced oscillation/
vibration
Surfactants
Acid/base
Sodium Hydroxide
to adjust pH
Surfactants
Proprietary extraction
agents. Hydrogen
Peroxide (H202)
added to react
with extracted CN
to form CO2 and NH3
Proprietary Surfact-
ants and other pro-
prietary chemicals
'Process evaluated^ used for site cleanup by the EPA. N/A = Not available.
Engim
\lletin: Soil Washing Treatment
-------
Table 3. Summary of Performance Data and Technology Status - Part I (continued)
Proprietary Vendor
Process/EPA
Highest Scale
of Operation
Year Operation
Began
Range of Particle
Size Treated
Contaminants
Extracted From Soil
Extraction Agent(s)
Non U.S. Processes (continued)
(12) EWHALSEN-
BREITENBURG
Dekomat System [2, p. 20]
(13) TBSC
INDUSTRIEVEITIETUNGEN
Oil Crep I System [7, p. 7]
(14) KLOCKNER
UMWELTECHNIK
Jet-Modified BSN [2, p. 20]
Pilot scale
8-1 0 cu. m/hr
Pilot scale
Pilot scale
N/A
1986
N/A
<80mm
Clays treated offsite
Sand <50 mm
Particles <1 00 (im
treated offsite
No more than 20%
<63 urn
Oil from sandy soil
Hydrocarbon and oil
Aliphatics and aromatics
with densities < water,
volatile organics, some
other hydrocarbons
Proprietary
Proprietary combina-
tion of surfactants,
solvents, and aromatic
hydrocarbons
None. Soil blasted
with a water jet (at
5,075 psi)
Table 3. Summary of Performance Data and Technology Status - Part II
Proprietary Vendor
Process/EPA
Byproduct Wastes
Generated
Extraction
Equipment
Efficiency of
Contaminant Removal
Additional
Process Comments
U.S. Processes
(1) SOIL CLEANING
OF AMERICA
(2)* BIOTROLSOIL
TREATMENT SYSTEM
(BSTS)
(3) EPA's MOBILE
COUNTER-CURRENT
EXTRACTOR
(4)* EPA's FIRST
GENERATION PILOT
DRUM SCREEN
WASHER (PDSW)
(5)* MTA REMEDIAL
RESOURCES (MTARRI)
Froth Flotation
Wet oil
Oil and grease
Sludge from bio-
ogjcal treatment
Clay fraction
Recovered organics
(extractor skimmings)
Spent
carbon (oversize)
Sludge
Flocculated fines
Flocculation froth
Screw conveyors
Agitated
conditioning tank
Froth flotation
Slurry bioreactor
Drum screen
Water knife
Soil scrubber
4-Stage
Counter-current
chemical extractor
Drum screen
washer
Reagent blend
tank
Flotation cells
Counter-current
decantation
Contam- Removal Residual
inant Efficiency % ppm
Oil and 50-83 250-600
grease
For the case presented:
90-95% for Pentachlorophenol;
to residuals <1 15 ppm.
85-95% for most other organics;
to residuals <1 ppm.
Contam- Removal Residual"
inant Efficiency % ppm
Phenol 90 from in. soil 1
80 from or. soil 96
AS205 50-80 0.5-1.3
So/7 Size Res/-'
Contam-Fraction Removal dual
inant mm Effic.% ppm
Oil and 0.25-2 99 <5
grease <0.25 90 2400
Contam- Removal Residual
inant Efficiency 96 ppm
Volatile
organics 98-99+ < 50
Semivolatile
organics 98-99+ < 250
Most fuel
products 98-99+ < 2200
Three screw conveyors operated
in series, hot water with surfactant
injected into each stage. Final soil
rinse on a fourth screw conveyor.
Dewatered clays and organics to be
treated offsite by incineration,
solidification, etc. Washed soil was
approx. 78% of feed. Therefore,
significant volume reduction was
achieved.
Clay fraction treated elsewhere.
Process removal efficiency
increases if extracting medium is
heated. Install wet classifiers
beneath the PDSW to remove
waste water from treated soil.
Auger classifiers are required to
to discharge particles effectively.
Flotation cells linked by underflow
weir gates. Induced air blown
down a center shaft in each wll.
Continuous flow operation, froth
contains 5-1 0 wt% of feed soil.
'Process evaluated or used for site cleanup by the EPA. N/A = Not available.
8
Engineering Bulletin: Soil Washing Treatment
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Table 3. Summary of Performance Data and Technology Status - Part II (continued)
Proprietary Vendor
Process/EPA
Byproduct Wastes
Generated
Extraction
Equipment
Efficiency of
Contaminant Removal
Additional
Process Comments
Non U.S.
(6) ECOTECHNIEK BV
(7) BODEMSANERINC
NEDERLAND BV (BSN)
(8) HARBAUER
OF AMERICA
(9) HWZ
BODEMSANERINC BV
(10) HEIJMAN
MILIEUTECHNIEK BV
(11) HEIDEMIJ FROTH
FLOTATION
(12) EWHALSEN-
BREITENBURC
Dekomat System
(13) TBSC
INDUSTRIEVEITIET-
UNCEN
Oil Crep 1 System
(14) KLOCKNER
UMWELTECHNIK
High Pressure Water
Jet-Modified BSN
Wet oil
Oil/organics
recovered from
wastewater fines
Carbon which may
contain contami-
nants
Fines
Sludge containing
iron cyanide
Large particles —
carbon, wood, grass
Flocculated fines
sludge
Oil (if any) and silt
Contaminated float
Recovered oil
Flocculated fines
(sludge)
Oil phase contain-
ing Oil Crep 1
Oil/organics
recovered from
wastewater fines
Sludge
Jacketed, agitated
tank
Water jet
Conditioning tank
Low frequency
vibration unit
Scrubber
(for caustic
addition)
Upflow classifier
Mix tank
followed by soils
fraction equip-
ment — hydro-
clones, sieves,
tilt plate separators
Conditioning tank
Froth flotation
tanks
High-shear
stirred tank
Screw mixer
followed by a
rotating separation
drum for oil
recovery
Water jet -
circular nozzle
arrangement
About 90%
20,000 ppm residual oil
Selected results:
Contam- Removal Residual
inant Efficiency % ppm
Aromatics >81 >45
PNAs 95 IS
Crude oil 97 2300
Contam- Removal Residual
inant Efficiency 96 ppm
Organic-CI ND
Tot. organics 96 159-201
Tot. phenol 86-94 7-22.5
PAH 86-90 91.4-97.5
PCB 84-88 0.5-1.3
Contam- Removal Residual
inant Efficiency % ppm
CN 95 5-15
PNAs 98 15-20
Chlorin-HC 98 <1
Heavy metals 75 75-125
Contam- Removal Residual
inant Efficiency % ppm
Cyanide 93-99 <15
Heavy metal
cations approx. 70 <200
Contam- Removal Residual
inant Efficiency 96 ppm
Cyanide >95 5
Heavy metals >90 avg >1 50
Chlorin-HC >99 0.5
Oil >99 20
About 95% oil removed
>95% Removal of hydrocarbons
has been achieved. Results are
influenced by other contaminants
present.
Selected results:
Contam- Removal Residual
inant Efficiency 96 ppm
HC 96.3 82.05
Chlorin-HC >75. <0.01
Aromatics 99.8 <0.02
PAHs 95.4 15.48
Phenol >99.8
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REFERENCES
2.
3.
4.
5.
6.
7.
8.
9.
Assink, j.W. Extractive Methods for Soil
Decontamination; a General Survey and Review of
Operational Treatment Installations. In: Proceedings
from the First International TNO Conference on
Contaminated Soil, Ultrecht, Netherlands, 1985.
Raghavan, R., D.H. Dietz, and E. Coles. Cleaning
Excavated Soil Using Extraction Agents: A State-of-the-
Art Review. EPA 600/2-89/034, U.S. Environmental
Protection Agency, 1988.
Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA 540/2-88/004, U.S.
Environmental Protection Agency, 1988.
M.K. Stinson, et al. Workshop on the Extractive
Treatment of Excavated Soil. U.S. Environmental
Protection Agency, Edison, New Jersey, 1988.
Smarkel, K.L. Technology Demonstration Report - Soil
Washing of Low Volatility Petroleum Hydrocarbons.
California Department of Health Services, 1988.
Guide for Conducting Treatability Studies Under
CERCLA, Interim Final. EPA/540/2-89/058, U.S.
Environmental Protection Agency, 1989.
Nunno, T.J., J.A. Hyman, and T. Pheiffer. Development
of Site Remediation Technologies in European
Countries. Presented at Workshop on the Extractive
Treatment of Excavated Soil. U.S. Environmental
Protection Agency, Edison, New Jersey, 1988.
Nunno, T.J., and J.A. Hyman. Assessment of
International Technologies for Superfund Applications.
EPA/540/2-88/003, U.S. Environmental Protection
Agency, 1988.
Scholz, R., and ]. Milanowski. Mobile System for
Extracting Spilled Hazardous Materials from Excavated
Soils, Project Summary. EPA/600/52-83/100, U.S.
Environmental Protection Agency, 1983.
10. Nash, j. Field Application of Pilot Scale Sorls Washing
System. Presented at Workshop on the Extracting
Treatment of Excavated Soil. U.S. Environmental
Protection Agency, Edison, New Jersey, 1988.
11. Trost, P.B., and R.S. Rickard. On-site Soil Washing—A
Low Cost Alternative. Presented at ADPA. Los Angeles,
California, 1987.
12. Pflug, A.D. Abstract of Treatment Technologies, Biotrol,
Inc., Chaska, Minnesota, (no date).
13. Biotrol Technical Bulletin, No. 87-1 A, Presented at
Workshop on the Extraction Treatment of Excavated
Soil, U.S. Environmental Protection Agency, Edison,
New Jersey, 1988.
14. Superfund Treatability Study Protocol: Bench-Scale
Level of Soils Washing for Contaminated Soils, Interim
Report. U.S. Environmental Protection Agency, 1989.
15. Innovative Technology: Soil Washing. OSWER Directive
9200.5-250FS, U.S. Environmental Protection Agency,
1989.
16. 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.
17. 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.
18. ROD Annual Report, FY1989. EPA/540/8-90/006, U.S.
Environmental Protection Agency, 1990.
OTHER REFERENCES
Overview—Soils Washing Technologies For:
Comprehensive Environmental Response,
Compensation, and Liability Act, Resource Conservation
and Recovery Act, Leaking Underground Storage Tanks,
Site Remediation, U.S. Environmental Protection
Agency, 1989.
10
Engineering Bulletin: Soil Washing Treatment
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