EPA/60G/2-C9/034
June 1989
CLEANING EXCAVATED SOIL USING EXTRACTION AGENTS:
A STATE-OF-THE-ART REVIEW
by
R. Raghavan
E. Coles
D. D1etz
Foster Wheeler Enviresponse, Inc.
Livingston, NJ 07039
Contract Number 68-03-3255
Project Officer
Darlene Williams
Releases Control Branch
Superfund Technology Demonstration Division
Risk Reduction Engineering Laboratory
Edison, NJ 08837
RISK REDUCTION ENGINEERING LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OH 45268
-------
NOTICE
The information in this document has been funded wholly or in part by the
United States Environmental Protection Agency under Contract No. 68-03-3255 to
Enviresponse, Incorporated. It has been subject to the Agency's peer and
administrative review, and it has been approved for publication as an EPA
document. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
-------
FOREWORD
Today's rapidly developing and changing technologies, and industrial
products and practices frequently carry with them the increased generation of
materials that, if improperly dealt with, can threaten both public health and
the environment. The U.S. Environmental Protection Agency is charged by
Congress with protecting the Nation's land, air, and water resources. Under a
mandate of national environmental laws, the agency strives to formulate and
implement actions leading to a compatible balance between human activities and
the ability of natural systems to support and nurture life. These laws direct
the EPA to perform research to define our environmental problems, measure the
impacts, and search for solutions.
The Risk Reduction Engineering Laboratory is responsible for planning,
implementing, and managing research, development, and demonstration programs
to provide an authoritative, defensible engineering basis in support of the
policies, programs, and regulations of the EPA with respect to drinking water,
wastewater, pesticides, toxic substances, solid and hazardous wastes, and
Superfund-related activities. This publication is one of the products of that
research and provides a vital communication link between the researcher and
the user community.
This report reviews technologies that have potential for cleaning
excavated soils by use of extraction agents. Areas for further research and
development are identified to aid in developing potential treatment
technologies for volume reduction of Superfund soils prior to land disposal.
For further information, please contact the Superfund Technology
Demonstration Division of the Risk Reduction Engineering Laboratory.
E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory
-------
ABSTRACT
In response to the RCRA Hazardous and Solid Waste Amendments of 1984
prohibiting the continued land disposal of untreated hazardous wastes, the
U.S. Environmental Protection Agency (EPA) has instituted a research and
development program for new technologies to treat RCRA and Superfund wastes.
As part of this research program, technologies applicable to cleaning
excavated soils were reviewed.
This report presents a state-of-the-art review of soil washing
technologies and their applicability to Superfund sites in the United States.
The review includes Superfund site soil and contamination characteristics; as
well as soil cleaning technologies, their principles of operation, and process
parameters. The technical feasibility of using soil washing technologies at
Superfund sites in the United States is assessed.
Contaminants are classified as volatile, hydrophilic, or hydrophobic
organics; PCBs; heavy metals; or radioactive material. Soils are classified
as either sand, silt, clay, or waste fill.
Three generic types of extractive treatments are identified for cleaning
excavated soils: water washing augmented with a basic or surfactant agent to
remove organics, and water washing with an acidic or chelating agent to remove
organics and heavy metals; organics-solvent washing to remove hydrophobic
organics and PCBs; and air or steam stripping to remove volatile organics.
Although extraction of organics and toxic metal contaminants from
excavated sandy/silty soil that is low in clay and humus content has been
successfully demonstrated at several pilot-plant test facilities, extraction
from clay and humus soil fractions is more complicated.
More pilot-scale testing must be conducted to support any statement on the
environmental and economic practicability of extraction technologies at sites
in the United States.
This report was submitted in partial fulfillment of Contract No.
68-03-3255 by Enviresponse, Inc. under the sponsorship of the U.S.
Environmental Protection Agency.
-------
CONTENTS
Foreword iii
Abstract iv
Figures vi
Tables vii
Abbreviations viii
Acknowledgments ix
1. Introduction 1
Background 1
On-site Soil Treatment 1
Soil Cleaning for Safe On-site Redeposit 2
2. Conclusions and Recommendations 4
Conclusions 4
Recommendations 5
3. Patterns of Contamination and Soil Composition at NPL Sites . . 6
Classification of Contaminants 6
Soil Classification 8
Site Survey Procedures 8
Apparent Patterns of Soil and Contaminant Occurrence ... 9
4. Extraction Treatments To Clean Soil 11
Process Classifications: An Overview 11
Water Washing With Extraction Agents 13
Solvent Extraction 30
Air Stripping 39
References 46
Bibliography 51
Appendix: Priority Pollutants and Acutely Hazardous Substances ... 67
v
-------
FIGURES
Number Page
1 General block diagram for soil cleaning 16
2 Rotocel percolation extractor ....... ... 33
3 Lurgi frame belt extractor ......... 35
4 DeSmet continuous-belt extractor ...... , . , 35
5 DeDanske Sukkerfabrtker (DDS) diffuser , , 3?
v L
-------
TABLES
Number Page
1 Summary of Total Soil Volume and Contaminent Types at
Surveyed Region II NPL Sites 10
2 Extraction Treatment vs. Contaminant Classification .... 12
3 Soil-Contaminant Technology Matrix 14
4 Selected Results from Heijman's Soil Cleaning Runs 18
5 Selected Results from HWZ Soil Cleaning Runs 18
6 Selected Results from BSN Soil Cleaning Runs 19
7 Selected Results from Klockner Soil Cleaning Runs 21
8 Selected Results from Harbauer Soil Cleaning Runs 21
vi i
-------
ABBREVIATIONS
APOC Ammonium pyrrolidine carbodithiate
atm Atmosphere
B.E.S.T. Basic Extraction Sludge Treatment
°C Degrees Celsius
CHC Chlorinated hydrocarbons
CERCLA Comprehensive Environmental Response, Compensation, and Liability
Act (Superfund), 42 U.S.C.A. Chapter 9601 et seq.
cm Centimeter
CFR Code of Federal Regulations
DTPA Diethylenetriamine pentaacetic acid
EDTA Ethylenediaminetetraacetic acid
EPA Environmental Protection Agency
EP Tox Extraction Procedure Toxicity (40 CFR 260.20, 260.21)
ERT Emergency Response Team
QF Degrees Fahrenheit
FS Feasibility Study
g Gram
hr Hour
HSWA Hazardous and Solid Waste Amendment (to RCRA)
kg Kilogram
kw Kilowatt
L Liter
M Molar
m3 Cubic meters
mg Milligram
mm Millimeter
MM Million
NPL National Priority List (established under CERCLA, 42 U.S.C.A.
Chapter 9601 et seq, Section 105(B)
NTA Nitrilotriacetic Acid
PCB Polychlorinated biphenyls
PNA, PAH, Polynuclear aromatic hydrocarbons
ppm Parts per million
psi Pounds per square inch
RAMP Remedial Action Master Plan
RCRA Resource Conservation and Recovery Act (42 U.S.C.A. Chapter 9601
et seq)
RI Remedial Investigation
SARA Superfund Amendments and Reauthorization Act of 1986 (Public
Law 99-499)
TEA Triethylamine
USATHAMA U.S. Army Toxic and Hazardous Materials Agency
um Micron
VOC Volatile organic compounds
vi i i
-------
ACKNOWLEDGMENTS
The authors gratefully acknowledge the intelligent and resourceful
guidance received over the life of this project from project officers A. Roubo
and D. Williams. The continuing contribution of F. Freestone and Dr. J.
Brugger, Releases Control Branch, Risk Reduction Engineering Laboratory, U.S.
Environmental Protection Agency, has been invaluable throughout this project.
In addition, contributions and guidance from R. Rayford of Enviresponse,
Inc., P. Albulescu of Foster Wheeler USA, and C. Marlowe and R. Evangelista
formerly of Enviresponse are deeply appreciated.
The editorial and word processing support and cooperation of D. Mausner,
M. DeFort, and C. Malinak of Enviresponse, inc., and J. Rabe of Foster Wheeler
Development Corporation are appreciated.
ix
-------
SECTION 1
INTRODUCTION
BACKGROUND
Under the Comprehensive Environmental Response, Compensation, and
Liability Act of 1980 (CERCLA) as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA), clean up activities at hazardous waste
sites must reduce the toxicity, mobility, and volume of hazardous substances.
The 1984 amendment to the Resource Conservation and Recovery Act (RCRA), the
Hazardous and Solid Wastes Amendment (HSWA), was created in large part in
response to citizen concerns that existing methods of hazardous waste
disposal, particularly land disposal, were not safe [1].
The 1984 RCRA amendments prohibit the land disposal of untreated
hazardous waste unless the Environmental Protection Agency (EPA) finds that
there will be "no migration of hazardous constituent for as long as the wastes
remain hazardous [1]." The land ban provisions of the 1984 RCRA amendments
have given considerable impetus to developing more economic and more effective
means of treating waste. EPA is now sponsoring research on new treatment
technologies to destroy, detoxify, or incinerate hazardous waste; on ways to
recover and reuse hazardous waste; and on methods to decrease the volume of
hazardous waste requiring treatment or disposal [1]. On-site treatment
technologies that remove or decrease contaminant levels may achieve a more
positive control than containment techniques. Off-site disposal in landfills
probably will be allowed in the future, but only when no treatment technology
is available, because transportation of a hazardous waste creates
opportunities for spills and accidents. In addition, as landfill disposal
becomes more expensive and as hazardous waste transportation is more
stringently regulated, on-site waste treatment technologies will become more
desirable--if they are technologically demonstrated, environmentally safe, and
economical.
ON-SITE SOIL TREATMENT
In response to the RCRA Amendment of 1984 which prohibits the continued
land disposal of selected groups of untreated hazardous waste in the U.S., the
EPA has instituted research and development programs for new treatment
technologies for RCRA and Superfund wastes.
One of the research areas initiated by the EPA is cleaning excavated
contaminated soil by extraction agents. Cleaning (washing) excavated soils
holds promise for being applicable to all contaminants.
1
-------
SOIL CLEANING FOR SAFE ONSITE REDEPOSIT
Soil cleaning employing extraction agents consists of soil excavation,
above-ground onsite treatment, isolation and removal or destruction of the
contaminant, and redeposit of the cleaned soil. Each technique used to
separate the contaminant from the soil requires an extraction agent--a liquid,
gas, chemical additive, or a combination of agents. The agent must mobilize
the contaminant, which is chemically or physically attached to the soil
particles. Because of some complex interactions between contaminants and
certain soil fractions (clay and humus), further research and development work
is needed.
As a first step, this report reviews the technologies that may be
applicable for cleaning (washing) excavated soil. The purpose is to examine
and evaluate physical separation and extraction technologies in the context of
their applicability to soil cleaning. Specifically, this report:
1. surveys the contaminants (by type and concentration) and soil (by
type and quantity) at the various NPL* sites to define the most
frequently occurring problems at these sites,
2. reviews the extractive treatment technologies that have potential
for cleaning the contaminants from soils, and
3. recommends areas for future research.
As of March 1987 a total of 951 sites are either on or proposed for inclusion
on the NPL (40 CFR 300 Appendix B).
Section 2 of this report contains conclusions and recommendations for
further research and development efforts in this area.
A manual search of the EPA files containing data on NPL sites in New
York, New Jersey, and Puerto Rico was performed to identify the most
frequently occurring problems. Section 3 presents the results of the survey.
Reviews of the extractive treatment technology show that there are three
generic types of extraction processes for cleaning contaminated soils:
1. Water Washing with Extraction Agents;
Surfactants that promote the solubility of the contaminants in
water;
Chelating additives that chemically react with metal ions and
promote their solubility; and
Acid or alkaline solutions that mobilize, neutralize, or
destroy the contaminant.
^Section 105 of CERCLA required EPA to establish a list of hazardous waste
sites (National Priority List).
2
-------
2. Solvent Extraction of Organic Contaminants: An organic solvent
dissolves and mobilizes the contaminant into the solvent.
3. Air Stripping of Volatile Organic Contaminants: Agents such as
steam or air are applied. Heat, vacuum, or both increase the
extraction rate.
These processes are reviewed in Section 4.
3
-------
SECTION 2
CONCLUSIONS AND RECOMMENDATIONS
CONCLUSIONS
The following conclusions and recommendations have emerged from this
literature review of theoretical, bench-scale, and pilot-scale investigations
on state-of-the-art technologies for the extraction of contaminants from soil.
¦ At 57 of the 82 sites surveyed in Region II, the contaminated soil
is characterized as sand or silt. Total sandy/silty soil volume
exceeds 10 million cubic meters. Pilot-scale tests conducted by
TNO, Heijmans, HWZ Bodemsanering, BSN, and Ecotechniek show that
sand or silt can be washed.
• Above-ground extraction of organics and heavy metals is feasible
from sandy soil containing very low levels of clay and humus
fractions.
¦ Above-ground extraction of organics and heavy metals from clay and
humic soil fractions has not been demonstrated on the pilot-plant
scale.
¦ Separation of the extractant from the soil and regeneration of the
extractant have not been successfully demonstrated for clay soils.
¦ Contaminant extraction experience does provide enough information to
support a decision on the technical feasibility of applying the
technology at NPL sites.
¦ More applied pilot-scale testing must be conducted to support any
statement on the environmental and economic practicability of
extraction technologies.
¦ Experience with contaminant removal via water washing at the bench,
pilot, and prototype scale supports the technology as it applies to
sandy and silty soils. Its economic competitiveness with other
remedial technologies such as incineration or fixation is implied at
this time, but not fully quantified.
4
-------
RECOMMENDATIONS
A program is needed that would include:
¦ Characterization of soil at NPL sites from a soil washing
perspective. This would include particle size distribution,
mineralogical observations, physical and chemical analyses, etc.
m Bench-scale testing program to establish the required processing
configurations and operating conditions of the various wastewater
treatment and regeneration subsystem options.
¦ Preliminary process design, sizing, and costing of a modular
transportable pilot-plant system to determine process economics for
comparison with incineration and other remedial technologies.
¦ Design, construction, and operation of a modular transportable
pilot-scale unit to demonstrate applicability at selected NPL sites.
¦ Research and development efforts to broaden the application of
washing soil containing high clay/humus fractions, if economically
justified.
5
-------
SECTION 3
PATTERNS OF CONTAMINATION AND SOIL COMPOSITION AT NPL SITES
A variety of contaminants and soil types can be found at Superfund
sites. A survey of NPL site information files was conducted to determine the
possible contaminants and soil types that are prevalent at these sites. Based
on the survey, the various soil-contaminant type pairs were grouped to
identify the pairs occurring with highest frequency. These pairs were matched
with the potential extractive technologies that can be applied for cleaning
soils, thus helping to determine which of the potential extractive
technologies should be pursued further. The identification of the various
soil-contaminant pairs is also essential in selecting and assessing agents
used in the processes applicable to soil cleaning.
CLASSIFICATION OF CONTAMINANTS
The four most common multicompound concentration analyses performed on
soil samples from NPL sites are those listed in 40CFR 136 [2] and the EPA Test
Method for Evaluating Solid Waste (SW846) [3], These are:
¦ Priority Pollutant Scan
¦ Priority Pollutants + 40
¦ Extraction Procedure Toxicity Test
¦ Partial scans of the above three (e.g., Volatile Organics Analysis)
These analyses are performed to determine the level of concentration of
the priority pollutants and acutely hazardous substances chat are listed in
40CFR 122.21, Appendix D [1] (see Appendix). These contaminants were grouped
by the following four physical and chemical parameters that affect the ability
of an extraction agent or process to mobilize them:
¦ water solubility;
¦ vapor pressure;
¦ octanol/water partition coefficient; and
¦ density.
6
-------
These parameters were used to create separate lists of hydrophilic
organic compounds, hydrophobic organic compounds, volatile organic compounds,
and heavy metals (see Appendix). An additional contaminant classification,
which is not addressed in this report, is radioactive materials. Definitions
of the contaminant classifications addressed here are:
¦ "Volatile"--Having a vapor pressure greater than 5 mm of mercury at
25°C.
¦ "Hydrophilic"--Having a solubility in water over 10 g/L at 25°C.
¦ "Hydrophobic"--Possessing an octanol/water partition coefficient
(Kow)* greater than 100.
¦ "Heavy metal"--Toxic metals and their compounds in ionic form.
This choice of definitions makes some highly soluble contaminants both
hydrophilic and hydrophobic, while very slightly soluble materials are
neither. Professional judgment was used to assign a single classification to
each contaminant. Since Kow data are not available for all of these
materials, some of the characterizations were based on statements in the
reference literature like "slightly soluble in water, very soluble in benzene."
Physical property information used to determine contaminant
classification were obtained from:
¦ The CRC Handbook of Chemistry and Physics [4]
¦ The Chemical Engineering Handbook [5]
¦ The Condensed Chemical Dictionary [6]
¦ Sax's Dangerous Properties of Industrial Materials [7]
¦ The Handbook of Environmental Data for Organic Compounds [8]
¦ The Merck Index of Chemicals [9]
¦ The Chemical Profiles Appendix to the EPA Chemical Emergency
Preparedness Program [10]
*The octanol/water partition coefficient is defined as the ratio of a
chemical's concentration in the octanol phase to its concentration in the
water phase.
7
-------
SOIL CLASSIFICATION
Attempts were made to characterize the soil present at each NPL site, but
because detailed information on soil type was not available, gravel, sand,
silt, clay, and waste fill were used as soil categories. The waste fill
classification refers to dump sites where waste fill predominates and the type
of associated soil is not defined. The municipal and chemical waste found in
landfill sites are examples of waste fill. The humus or organic matter in Che
soil was noted when that identifying information was available.
It should be noted that soils are not homogenous and this classification
system only assures that a soil classified as sand, silt, or clay will have a
major fraction as sand, silt, or clay, respectively. For example, soils
classified as sandy may also have silt or clay lenses in them.
SITE SURVEY PROCEDURES
The following information was obtained on each NPL site to evaluate
applicability of potential extraction technologies:
¦ Name of site
¦ Types of contaminants present (see Appendix)
¦ Quantity of contaminated soil (including waste)
¦ Types of soil
¦ Average concentrations of contaminants
Originally, only NPL site information data bases maintained by EPA
contractors were to be searched. The most likely data bases were identified
by conferring with the personnel at CERCLA offices in Washington, D.C. The
data bases were examined for the range of sites and the type and amount of
information they provided. Data bases examined were:
¦ MITRE Data Base: Lists every NPL site and no other sites. The
database contains information on contaminants present in
groundwater, surface water, and air. There is no information on
soil type, soil quantity,or contaminants in soil.
¦ Damage Incident Data Base: Lists most NPL sites and many others.
Information on soil contaminants, contaminant concentrations, and
quantity of contaminated soil is present, but there is no
information on soil type.
¦ NPL Records of Decision Data Base: Lists 130 NPL sites. The data
base consists of information on soil contaminants, contaminant
concentrations, and quantity of contaminated soil; there is no
information on soil type.
8
-------
CDM CERCLA Waste Tvpe Data Base: Lists 39 NPL sites. Information
encompasses soil contaminants and quantity of contaminated soil; no
information is provided on soil type or contaminant concentrations.
The available electronic data bases did not contain all the information
needed for this study. Therefore, EPA's files on as many NPL sites as
possible were examined manually. A manual search of EPA Region II files of
the NPL sites in New York, New Jersey, and Puerto Rico was performed.
Files on 194 sites were examined. The information on soil contamination
was not adequate for assessment regarding soil washing in 56 of the files.
Remedial/removal work was complete at 8 of the sites. Ground water (as
opposed to soil) contamination was the important consideration at 35 sites,
and no quantitative information on soil contamination was provided at ground
water sites. Other types of nonsoil contamination were important at
13 sites. At the remaining sites, soil contamination data were adequate.
Most of the concentrations reported in these files were not: computed, but
are approximated averages of many individual data points listed in raw data
tables at the back of Remedial Investigation (RI), Feasibility Study (FS),
Remedial Action Master Plan (RAMP), Phase I, or Phase II reports. The
approximate average was used because a simple arithmetic average would
over-represent less-contaminated soil, which would be neither excavated nor
processed. The type of soil was sometimes stated in great detail, as in an RI
or FS. It was often only vaguely described (e.g., "This property is
swampy."). Because the goal of the study was to obtain a soil contamination
profile, precision was sacrificed in a few individual cases to increase the
number of sites listed. The quality of the data was considered good enough
for a profile study, but not good enough for definitive characterization of
individual sites.
APPARENT PATTERNS OF SOIL AND CONTAMINANT OCCURRENCE
The 82 sites that had adequate soil contamination data were included in
the data base for this study. If the Region II data are proportionally
representative of the nation, then soil contamination at 402 of the 951 NPL
sites can be assumed to have been characterized.
From data on soils and contaminants at 82 sites, 32 soil-contaminant type
pairs were identified along with their frequencies of occurrence (Table 1).
Many of the sites have more than one type of contaminant present; these sites
appear under each applicable pair category in Table 1. Of the 176 occurrences
identified in the search of the soil-contaminant type pairs as shown in
Table 1, only three occur at significantly greater frequency than the
remaining 29 pairs. These are hydrophobic volatile compounds, hydrophobic
nonvolatile compounds, and heavy metals, all of them in sites with sandy
soil. A typical site is about 40,000 cubic meters of sand with contaminant
levels between 100 and 1,000 ppm. The occurrence of multiclass contamination
at a site makes the requisite cleanup technology more complex. These are best
assessed on a category-by-category basis.
9
-------
TABLE 1. SUMMARY OF TOTAL SOIL VOLUME AND CONTAMINANT TYPES AT SURVEYED REGION II NPL SITES
Soil type
Sand Silt Clay Uaste Total
No. of Soil volume No. of Soil volume No. of Soil volume No. of Soil volume No. of Soil volume
Contaminant sites MM nr sites MM m* sites MM m* sites MM nr sites MM m*
Hydrophilic volatile
12
0.73
3
0.24
4
0.03
7
14.83
26
15.83
Hydrophilic nonvolatile
4
0.51
1
0.61
1
0.01
2
0.91
8
2.04
Hydrophobic volatile
24
3.41
6
0.82
5
0.03
6
7.41
41
11.67
Hydrophobic nonvolatile
27
3.36
6
0.87
4
1.18
6
8.15
43
13.56
PCBs
4
0.47
1
0.01
2
1.15
1
0.05
8
1.68
Heavy Metal
20
6.42
8
1 .18
3
0.43
10
17.2
41
25.23
Other Inorganic
2
0.05
1
0.01
-
-
2
4.59
5
4.65
Radioactive
3
0.21
1
0.03
1
0.02
0.06
5
0.32
-------
SECTION 4
EXTRACTION TREATMENTS TO CLEAN SOIL
PROCESS CLASSIFICATIONS: AN OVERVIEW
Three primary types of extraction processes for cleaning contaminated
soil are:
1. Water Washing with Extraction Agents:
Surfactants that promote the solubility of the contaminants in
water;
Chelating additives that chemically react with metals and
promote their solubility; and
Acid and/or alkaline solutions that mobilize, neutralize, or
destroy the contaminant.
2. Solvent Extraction of Organic Contaminants: Organic solvent
dissolves and mobilizes the contaminant into the solvent.
3. Air Stripping of Volatile Organic Contaminants: Agents such as
steam or air are applied. Heat, vacuum, or both increase the
extraction rate.
Water washing with extractive agents is applicable for cleaning
nonvolatile hydrophilic and hydrophobic organics and heavy metals from soils.
The solvent extraction processes show potential for cleaning nonvolatile
hydrophilic and hydrophobic organics from soil. Air stripping processes are
limited to cleaning soil of volatile organics.
These extraction treatment classifications encompass the information
found in the literature pertinent to cleaning contaminated soil above ground.
The relationship between extraction treatment and contaminant classifications
is given in Table 2.
The information discussed in this section was obtained from the open
literature. Water washing of soils with chelating agents and surfactants has
undergone some recent bench-scale and pilot-scale testing. The use of acids
and bases to remove metals and organics from contaminated soils has been
successful. Soil washing with organic solvents has been tried on a limited
11
-------
TABLE 2. EXTRACTION TREATMENT VS. CONTAMINANT CLASSIFICATION*
Contaminant classification
Hydrophilic Hydrophobic Volatile Heavy Other
Extraction treatment organics organics organics metals inorganics Radioactive
Water washing
Surfactants X
Chelation
Acid and/or base X
Solvent Extraction
Stripping
*Based on experimental treatment processes that have been proven effective on
specific contaminants.
12
-------
scale and for limited types of contaminated soil. Volatile organic stripping
of soil with air has been utilized, whereby fresh air is induced or forced
into the subsurface, and the vapor-laden air is withdrawn under vacuum from
recovery wells.
Most of the soil cleaning processes involve intimate mixing of the
extractant with soil, followed by solid/liquid separation where the cleaned
soil is separated from the extractant fluid. The extractant is then cleaned
of the contaminant and recycled as required. Table 3 shows the
soil-contaminant type pairs along with their frequency of occurrence**. The
type of potential extractant along with the applicable extractant and
solid/liquid separation equipment for the soil-contaminant type pairs are also
shown in Table 3. Some of the potential technologies that can be used to
clean the extractant fluid as suggested by researchers and process developers
are also shown in Table 3.
Cleaning soil contaminated with radioactive material was beyond the scope
of this study and is not discussed.
In the next section, the generic extraction processes are described. For
each of the processes the general process considerations, process description,
related experience, and procedures for contaminant removal from soil are
discussed. For the contaminants removal, the process parameters that will
affect the process are identified. The specific soil cleaning experiences
related to the contaminants removal are also presented.
WATER WASHING WITH EXTRACTION AGENTS
General Process Considerations
In water washing with extraction agents the washing solutions can be
basic aqueous solutions (caustic, lime, slaked lime, or industrial
alkali-based washing compounds); acidic aqueous solutions (sulfuric,
hydrochloric, nitric, phosphoric, or carbonic acids); or solutions with
surfactant or chelating agents. Hydrogen peroxide, sodium hypochlorite, and
other oxidizing agents also are used to chemically change the contaminants. A
strong (highly ionized) basic or surfactant solution can be used for some
organic extraction, and strong (highly ionized) acidic or chelating agent
solutions can be used for metal extraction. The surfactant and chelating
solutions have a moderate (almost neutral) pH, making equipment metallurgy
simpler, and operation safer. The successful development of a means to clean
soil with surfactants and chelating agents is important because most soil at
NPL sites is contaminated with organics and heavy metals.
^Frequency of occurrence is based on 82 Region II NPL sites.
13
-------
M
X X X X
• SAND
SOIL
TYPE
X X X X
• SILT
X X X X
• CLAY
X
X
X
• HYDROPHOBIC -
NONVOLATILE ORGANICS
CONTAMINANT
TYPE
X
X
X
• HYDROPHILLIC -
NONVOLATILE ORGANICS
X
X
X
• VOLATILE ORGANICS
X
X
X
• HEAVY METALS/
INORGANICS
2.3
06
5.1
17
en cn o uj
— — en x-
ro
ro O ro en
cn en co co
• FREQUENCY OF
OCCURRENCE (°/o)
X
X
X
• WATER
EXTRACTANT
X
X
• WATER/SURFACTANT
X
X
X
• WATER/CHELATE
X X
X X
X X
• WATER/ACID/BASE
X
X
X
• WATER/pH/CONTROL
X
X
• SOLVENT WASH
X
X
• STEAM OR AIR
X XX
X XX
X XX
• STIRRED TANK
EXTRACTOR TYPE
X X
• INCLINED SCREW
X
X
• ENDLESS BELT
X
X
• H0L0-FLITE SCREW
X
X
• ROTARY KILN
X
X
• FLUID BED
X XX
X XX
• CORRUGATED PLATE
GRAVITY SEPARATOR
SOLID-LIQUID
SEPARATION
X XX
• HYDROCYCLONE
X XX
• BASKET/PUSHER
CENTRIFUGE
X XX
• VACUUM FILTER
X X
X X
X X
• CHEMICAL/BIOLOGICAL
OXIDATION
X
X
X
• HYDROLYSIS
33
m m
X X
X X
X X
• CARBON FILTRATION
m —1
m
3D Q
P
§-
X
X
• ION EXCHANGE
X
X
~ PRECIPITATION/
ELECTROLYSIS
X
X
• CONDENSATION/
INCINERATION
CD
-------
Process Unit Description
Rulkens, et al., proposed a general block diagram of the equipment train
that can be used to extract contaminants from excavated sandy soil
(Figure 1) [11]. They also discuss commercially available types of equipment
and processes for each unit operation. The excavated soil is pretreatcd by
screening to remove large objects like pieces of wood, concrete, and drums;
and hard clods of soil are reduced in size. These large objects are cleaned
separately. The pretreated soil is mixed thoroughly with extraction agents,
to strip the contaminant from the soil. This is followed by solid/liquid
separation where the coarse fraction of the soil is separated. The extraction
agent with contaminant and smaller soil particle (clay and fine silt)
undergoes further solid-liquid separation where fine soil fractions arc
separated as much as possible. The extraction agent Is cleaned and recycled.
The separated soil fraction undergoes post-treatment where it is cleaned of
any residual extraction fluid. Review of the literature reveals extractors
and other equipment that can be used to treat excavated sandy, silt, clay, and
humus soil. The equipment used is noted in the following section.
Related Experience
To date, several aqueous extraction systems for cleaning excavated
contaminated soil have been demonstrated on a pilot scale. Demonstrating the
operation of the equipment involves pretreatment, extraction of contaminated
soil, and post-treatment of the extractant. The effective separation of the
extractant from the soil, concentration of the contaminant, recycle of the
regenerated extracting agent, and destruction of the contaminant have been
demonstrated at a pilot level for very limited types of contaminated soil.
Described below are the soil pretreatment/extraction
experiences and post-treatment experiences.
Soil Pretreatment and Extraction Equipment Experience--
Limited experience with pilot-scale size equipment indicates that sandy
soil probably can be processed. The processing of clays and silts has not
been demonstrated and would involve developing unit processes to treat these
fine colloidal soil fractions.
Netherlands Bromide Removal from Sand Study [121 --Reports published in
November 1982 describe laboratory and pilot-plant-scale investigations
undertaken in the Netherlands for removal of organic bromine compounds from
soil. Sandy soil containing less than 10 percent clay and humus was cleaned
by a 2:1 caustic solution (pH >11). The soil was pretreated by grinding in a
low speed pen mill to reduce the size of soil clods. A 1-ton/hr inclined
(306) screw conveyor was used to extract the contaminant and separate the
extractant from the soil. The soil and fresh extractant were fed into a
hopper at the lower end of the screw. The spent extractant was removed as
overflow from the hopper, and the clean soil was discharged from the screw
top. The test information was used to engineer a future on-site treatment
plant.
15
-------
CONTAMINATED
SOIL
SIEVING RESIDUE
POSTTREATMENT
OF SOIL
SOL (FINE
PARTICLES)
EXTRACTING
AGENT
PURIFED
EXTRACTING
AGENT
CLEAN
SOIL
o>
SOLtOS OR SLURRY
(MAINLY) LIQUID
SLUDGE
MIXING &
EXTRACTION
PRETREATMENT
OF SOIL
POSTTREATMENT
OF SOI
TREATMENT OF
EXISTING AGENT
SEPARATION OF
FINE PARTICLES
SEPARATION OF SOB.
AND EXTRACTING AGENT
SURPLUS
EXTRACTING
AGENT
Figure 1. General block diagram for soil cleaning. Reprinted from Rulkens, W.H., J.W. Assink and W.S. Van Gemert.
Project B: On-site Processing of Contaminated Soil. In: Contaminated Land Reclamation and Treatment,
M.A. Smith,ed. Published in cooperation with NATO committee on the Challenges of Modern Society.
Copyright © 1985 by Plenum Press, New York. Reprinted by permission of Plenum Press, New York.
-------
Heijman's Milieutechniek's Extraction Cleaning of Heavy Metal and Cyanide
from Soils f131 --Heijman's installation has been in operation since the spring
of 1985 and has 10 to 15 ton/hr soil-handling capacity. The process begins
with separating coarse (>10 mm) and fine materials by sieving and intensive
mixing of soil with extracting agents and oxidizing chemicals. This is
followed by coarse sand (>60 urn), low-density materials (grass, coke, etc.),
and silt separation by hydrocyclone, sieves, and tilt plate separators. The
extracting agent is cleaned by flocculation and coagulation. The cleaned
extracting agent is recycled. The process has potential for cleaning soil
contaminated with cyanides, heavy metals, and water-immiscible and low-density
hydrocarbons. Table 4 shows results of some of the runs of the Heijman
process. The process is suitable for soils that contain less than 30 percent
fine solids (<63 um) and humus-like compounds.
HWZ Bodemsanering's Extractive Cleaning of Cyanide Contaminated Sandy
Soils --The HWZ [13] plant, with soil handling capacity of 20 ton/hr, has been
in operation since 1984. The process scheme consists of separating the coarse
material (>10 mm); intensive mixing of soil and NaOH in a scrubber; washing
the soil with an extractive agent in an upflow classifier; and separating the
coarse sand, low-density particles (coke, grass, etc.), and silt by sieves and
hydrocyclone. The extracting agent is cleaned by pH adjustment followed by
flocculation and coagulation. The cleaned extractive agent is recycled.
Table 5 shows some of the results of the HWZ soil cleaning runs. The
extracting agent used in the soil cleaning process was a detergent [13].
Ecotechniek's Thermal Washing Installation for Cleaning Sandy Soil
Contaminated with Crude Oil M3]--This installation, in full-scale operation
since 1982, has a 20 ton/hr soil handling capacity. The process consists of
slurrying sand with water and indirectly heating with steam to a maximum of
90°C. Oil is dispersed in water, and any floating oil is skimmed off. The
sand is separated from the water, and the process water containing oil is
cleaned by sedimentation and skimming operations. The process is suitable for
separating crude oil that is less dense than water. The process temperature
is dependent on the type of oil to be separated. So far, 5,000 tons of beach
sand contaminated by oil spills have been cleaned using this process. Sands
containing 200,000 ppm of oil were cleaned to the 20,000 ppm level. The
treated sand was recycled for use in preparation of asphalt.
Bodemsanering Netherlands (BSNI High Pressure Washing of Sandy Soil
Contaminated with Oil [131--This installation, in operation since 1983,
separates oil from sandy soil. The plant has a 20 ton/hr soil handling
capacity and is transportable. The process consists of separating coarse
material (>100 mm) by sieving; high pressure jet washing of soil (<100 mm);
separation of coarse sand by sieves and hydrocyclone (>63 um); separation of
silt by sedimentation; separation of process water, oil, and fine mineral
fractions (<30 um) by oil/water separator and use of coagulants and
flocculants. An option is additional microbiological treatment of treated
sand and spent process water. The water is recycled to a high-pressure
washer. Table 6 shows the results of some of the BSN runs.
17
-------
TABLE 4. SELECTED RESULTS FROM HEIJMAN'S SOIL CLEANING RUNS'
Contaminant
Initial
concentration
(mg/kg)
Conceiitra t ion
after treatment
(mg/kg)
Removal
efficiency
(%)
Mineral oil
Galvanic CN
Zn
Cd
Ni
3,000-8,000
450
1,600-3,200
66-125
250-890
90-120
15
300-500
5-10
85-95
approx. 98
approx. 94
approx. 83
approx. 92
66-89
Source: Reference 13.
TABLE 5. SELECTED RESULTS FROM HWZ SOIL CLEANING RUNS'
Contaminant
Initial
concentration
(rag/kg)
Concentration
after treatment
(mg/kg)
Removal
effic iency
(%)
CN (gaswork)
PNA (gaswork)
Chlorinated
hydrocarbons
Zn
Pb
100-200
36
20-24
81
approx. 100
approx. 10
0.7
0.3-0.5
27
approx. 25
approx. 95
98
98
67
approx. 75
Source: Reference 13.
18
-------
TABLE 6. SELECTED RESULTS FROM BSN SOIL CLEANING RUNS*
Contaminant
Initial
concentration
(mg/kg)
Concentration
after treatment
(rag/kg)
Removal
eff ic icncy
(%)
Aromatics
240
45 +
81*
PNAs
295
lb
9b
Crude oil
79,000
2,300
97
*Source: Reference 13.
+The concentration of aromatics was reduced to 10 mg/kg on account of
microbiological activity 6 months after treatment.
19
-------
Klockner Umweltechnik, using a version of the BSN process, blasts soil
particles with a high-pressure water jet (5075 psi) to clean contaminated
sandy soils [14]. Klockner uses a circular water jet nozzle arrangement.
Test run results are shown in Table 7.
The process has potential for cleaning all types of soils with fines
(<63 um) not exceeding 20 percent. The developer claims the soil can be
cleaned of the following contaminants:
¦ all aliphatics and aroraatics with low densities (less than water);
¦ volatile contaminants; and
¦ some water soluble and biodegradable hydrocarbons.
Harbauer Soil Cleaning System [151--This wet extraction process uses
hydraulically produced oscillation or vibration to achieve the initial
separation of soil particles and contaminants. The prepared soil is mixed
with water and chemicals and is introduced into a decontamination chamber
where a vibrating screw conveyor moves the soil forward under constant
vibration. Hydraulically produced oscillations or vibrations at high energy
are applied axially to the conveyor to vibrate the soil particles and separate
the contaminants. The soil cleaned is separated from the extraction by
stages. In the first stage, coarse soil fractions (15 nun to 130 um) are
separated by sedimentation. In the second stage, medium soil fractions
(130-20 um) are separated by 5-step hydrocyclone. In the third stage, fine
soil fractions (20-15 um) are separated by vacuum filter press. The water is
cleaned using counter-current flotation and flocculation, followed by air
stripping and activated carbon filtration.
The treated water is recycled. Table 8 shows the results of a test run
with contaminated soil excavated from the Berlin-Mariendorf gas works
location. The soil grain size distribution shows that 37 percent of the soil
fractions are less than 100 micron in size. The unit has an average
throughput of 40 tons/hour with recovery of 95 percent of input soil by volume.
EWH-Alsen-Breitenburp: Pilot Plant to Glean Sandy Soil Contaminated with
Oil ri61--This pilot plant (DEKOMAT System) uses special reagents added to
water to clean sandy soil. After separation of large particles (>80 mm) by
grizzly screens, the reagent, soil and water are mixed in a high-shear stirred
tank. The cleaned soil is separated with different fractions using vibrating
screens, screw classifiers, hydrocyclones, and sedimentation tanks. The oil
is skimmed by an oil skimmer, and fine particles are separated by use of a
flocculant. The water is recycled. The clean soil is analyzed for residual
contamination and sent for redeposit. The clay and skimmed oil are analyzed
for hazardous material and either sent to a special incinerator for burning or
if clean used in cement production. The pilot plant has operating capacities
of 8 to 10 cubic meters/hour. The water to soil ratio is 1:1, and 95 percent
cleaning efficiencies are reported by the developer.
20
-------
TABLE 7. SELECTED RESULTS FROM KLOCKNER SOIL CLEANING RUNS*
Contaminant
Initial
concentration
(mg/kg)
Concentration
after treatment
(mg/kg)
Removal
efficiency
(%)
Hydrocarbons
Chlorinated
hydrocarbons
2,222
0.04
82.05
<0.01
96.3
100
Aromatics
PAHC
Phenol
12.4
333.0
5.44
<0.02
15.48
<0.01
99.8
95.4
100.00H
* Source: Reference 14.
+Phenol is highly soluble. Complete removal is expected and does no
indicate that this system is superior to others.
TABLE 8. SELECTED RESULTS FROM HARBAUER SOIL CLEANING RUNS*
Contaminant
Initial
concentration
(mg/kg)
Concentrat ion
after treatment
(mg/kg)
Removal
of£iciency
(%)
Petroleum ether
extract
PAHs
Phenol
Total Cyanide
476
752
60.5
5.3
67
2
ND
0.059
68
99.7
100
98.9
* Source: Reference 15.
-------
Lee's Farm Lead Extraction from Soils ri71--ln 1985, a lead-contaminated
soil at an NPL site was screened and crushed to <50 mm. The crushed soil was
washed by a 30 percent EDTA solution, using an inclined-screw washing unit.
One part of soil was mixed with three parts of extractant in a hopper at the
lower end of the screw. The equipment was operated solely as a batch unit
because the soil contained too many fines, overwhelming the ability of the
equipment to continuously separate the clean soil from the extractant. The
test information is being used to specify equipment that can handle clays for
future pilot-plant work at this site or other NPL sites.
EPA's Mobile System for Extracting Spilled Hazardous Materials from
Excavated Soil f18.191 --Pilot studies were performed to determine the
equipment train. Three unit operations were developed and tested:
¦ Water Knife--A thin, flat, high-speed jet was optimized to break up
clumps of soil and scrub contaminants from larger soil particles
like stone and gravel. Testing showed that this concept is very
effective.
¦ Rotary Drum Screener--A rotary drum was employed as a pretreatment
to mix the soil with the extractant and to separate the coarse and
fine particles.
¦ Extraction and Separation Concept--A four-stage counterflow
extraction process was built employing hydrocyclones between each
extraction tank to separate the soil and washing fluid.
Contaminated soil is fed to the first tank and mixed with extractant
from the first hydrocyclone. Froth flotation is used to produce
maximum mixing between the soil and extractant. The slurry
collected from the bottom of the tank is pumped to the first
hydrocyclone. Solids from the hydrocyclone are mixed in the second
tank with extractant from the second hydrocyclone. This procedure
is repeated until the cleaned soil is removed from the fourth and
final hydrocyclone. Spent washing fluid is withdrawn from the first
stage, while fresh extractant is added to the fourth stage tank.
Hot Water Process for Extraction of Oil from Tar Sand f201--The sand is
mixed with hot water and violently agitated to mobilize the oil. The sand/oil
mixture is continuously separated in a settling tank. The oil froth overflows
the tank and is separated by a centrifuge. Water is added to the centrifuge
to form another layer between the oil and sand.
Gasoline Removal from Sand f211 — A fixed-bed pilot test program was
sponsored by the American Petroleum Institute using a sand bed. Surfactants
were used to enhance the recovery of gasoline. The sand bed was about
3 square meters by 1.2 meters deep. Multiple applications by percolation
resulted in good recovery of the gasoline.
22
-------
Post-treatment Experience--
Treatment of the contaminated extractant is required so that purified
water and recovered additives can be recycled. Processing of a contaminated
extractant is similar to processing polluted water, which is a mature science
[22], Equipment is readily available for the processing unit operations
discussed below.
Biological Treatment--Most organic contaminants can be destroyed
biologically. Work at Rutgers University is extending this established
treatment concept to the field of hazardous waste [23,24]. The key unit
operation is a biological treatment bed for destroying organic chemicals in an
aqueous extractant.
Coagulation and Sedimentation f251 --Additions of coagulant and flocculant
to contaminated water can separate the colloidal organic and inorganic
contaminants from the water. This technique is also useful for removing fine
soil particles from the extraction fluid.
Ion Exchange--This technique is usually a polishing treatment for low
levels of ionic contaminants. In the case of radioactive contaminants, the
technique applies as a primary cleaning method.
Activated Carbon--Most organic contaminants are removed from water using
the carbon filter. This technique is the most useful in cleaning low levels
of toxic organics.
Supercritical Oxidation f261--This wastewater treatment process is very
effective in destroying all organics. Oxygen stored as liquid is fed to a
pressurized vessel with the aqueous slurry waste feed. The vessel is heated
and pressurized to approximately 400 to 650°C and 220 to 250 atm (above the
critical point) to destroy the contaminant. An additional benefit is that
some inorganics separate out from the supercritical water. End products are
innocuous: N2; C02; salts such as CaSO^, MgSO^, and FejSO^; and
clean water.
Photochemical Destruction [27. 281 --Ultraviolet light enhances chemical
reaction rates. This technique allows for destruction of organics at moderate
temperature. Oxidizing agents are added to enhance the destruction of
organics.
Oxidizing. Agent [291 --Oxidizers such as chlorine, hydrogen peroxide, and
ozone are used to destroy organics.
Electrolysis [301 --Electrolysis provides the means to regenerate the
chelate and recover the metal.
Volatile Stripping of Organics from Water f31.321 --Volatile organics ear-
easily be stripped from water in a scrubbing tower. The contaminant can be
either vented to atmosphere or destroyed by incineration.
23
-------
Filtering--Fine particles in the extractant can be removed by a filter.
The use of sand, diatomaceous earth, or some other type of porous disposable
layer might be required instead of conventional reusable filter material,
because soil fines may permanently plug the filter material.
Other filtration/separation techniques that may be useful in removing
fine particles from the extraction water include microfiltration,
ultrafiltration, hyperfiltration, and nanofiltration. The use of mechanical
cleaning or air or water actuated backwash techniques may mitigate fouling of
the filter media.
The postextractant treatments discussed above have not been demonstrated
fully for treating soil. Operating experience on a complete above-ground soil
cleaning facility is very limited. Existing studies are primarily at the
pilot level.
Procedures for Contaminant Removal from Soil
Hydrophilic Organic Contaminants Removal--
A hydrophilic organic is an organic compound that is soluble in water.
Examples of hydrophilic compounds are methylene chloride and aldehydes.
Important process parameters and experience in removal of hydrophilic
compounds from soil matrices are discussed below.
Process Parameters--
¦ j)H--For some organics, manipulation of pH is useful to improve the
mobility of the contaminant into solution. For example, phenols arc
easily mobilized with an alkaline solution. Reversing pH can be
used to separate the organic from water in a postextractant
treatment step.
¦ Humic Content in Soil--Humus in soil contains bonded water,
colloids, and chelates that retain the contaminant. A caustic
solution is used to free these contaminants by altering the surface
charge of the humic substrate allowing solubilization of the
contaminants.
¦ Agitation--A turbulent mixing process is required to disperse the
soil in the washing solution and to provide abrasion to break down
inhibiting film conditions in the soil.
¦ Time. Soil Loading, and Staging--Extraction time may be a more
important variable than water to soil ratio or number of extraction
stages. The economics will dictate the design specifications of
these variables.
¦ Wetting Agent--A wetting agent may be required to improve the
penetration of the water into the soil particles to mobilize the
contaminant.
24
-------
Specific Experience--Hvdrophilic contaminants are effectively removed by
in situ pump and treatment techniques. Therefore, the opportunities for
above-ground cleaning are limited. The only naturally occurring mechanism
competing for hydrophilic compounds in soil is the presence of humus in the
soil. Humic material (colloids) present above 1 percent and high contaminant
levels may favor above-ground treatment [33].
Hydrophobic Nonvolatile Organic Contaminants Removal--
A hydrophobic organic is defined as being insoluble in water. However,
some hydrophobic organics with an octanol/wator partition coefficient between
10 and 1,000 are referred to as slightly hydrophilic. These organics tend to
be found in the ground water because of natural washing by ground water
movements. The slightly hydrophilic organics are more easily washed than the
insoluble organics. Typical slightly hydrophilic compounds are aromatics and
halogenated hydrocarbons. Insoluble hydrophobics commonly found at NPL sites
are pesticides, heavy oils, and greases.
Process Parameters - -
¦ Surfactants - - Surface active agents are added to the water to reduce
the surface tension between two liquids or a liquid and a solid.
Surfactants provide the link between water (a polar compound) and
the hydrophobic contaminant (a nonpolar compound). Aqueous
surfactant washing is not applicable to soils with a high huinic
content.
¦ Caustic Agent--Soils high in humic content require a high pH
solution (pH 12) t.o mobilize some contaminant from the humus. The
caustic breaks down the organic structure and mobilizes the
contaminant if the contaminant docs not react with the caustic to
form an insoluble compound.
¦ Extraction Stages--More than one extraction step is required. The
contaminant level should be reduced by one order of magnitude per
step. The residence time in each step should be long enough to
achieve this reduction. The hydrophobic contaminant level at NPL
sites varies between 100 and 10,000 ppm, and thus may require two to
four stages of extraction.
¦ Agitation--Mixing is required to disperse the soil, but excessive
mixing will produce large amounts of sludge. The mixing should aid
in mobilizing the organic, but not be so intensive as to create an
excessive amount of fines which adds to the problem of soils washing
¦ Temperature--A temperature near the boiling point of water (can be a
slightly pressurized system) should aid in mobilizing the
contaminant. The contaminant is removed as a froth from each stage.
¦ Reactor Conf i p.urati on - - For contaminants that are slightly
hydrophilic and permeable, a fixed-bed arrangement is satisfactory.
For insoluble hydrophobics, a constantly stirred reactor is required
-------
¦ Solid-to-Extraction Solution Ratio--A ratio of one part solids to
one part extraction fluid is preferred to minimize the treatment of
the extractant. However, two to three parts of extraction fluid is
a more practical range with respect to equipment operation.
Specific Experience--The most recent and thorough investigation of
aqueous surfactants used for soil cleaning is discussed in a report sponsored
by the EPA [33]. Sandy soil with low humic content (<1/2 percent) was spiked
with two hydrophobic compounds-- crude oil and transformer oil containing
PCBs. Crude oil (1,000 ppm level) was reduced by 93 percent using 2 percent
each of Adsee 799 (Witco Chemical) and Hyonic NP-90 (Diamond Shamrock)
surfactants. The extent of removal of PCBs was 92 percent for 0.75 percent of
each surfactant.
Similar soil cleaning studies using surfactants were conducted by the
Texas Research Institute [21]. Gasoline was recovered from sand in a pilot
study by percolating an aqueous surfactant solution through a bed of
gasoline-contaminated sand using a combination of commercially nonionic
(Hyonic, PE-90) and anionic (Richonate, YLA) surfactants. Multiple washing
recovered 76 percent of the gasoline.
A bench-scale study conducted by Rutgers University in cleaning sandy
loam soil contaminated with organics showed 92 to 95 percent removal
efficiencies using a combination of 2 percent each of Adsee 799 and NP 100
surfactant (private communication, Dr. Rajput, Rutgers University, April 1988.)
Heavy Metals Extraction Using Chelating Agents--
All metal cations have one or more "reactive" sites available to ligands
(molecules that can bind to a metal ion to form a complex). An interaction
occurs at reactive sites between positively charged metal cations and
electron-donating ligands to form complexes. Chelants are ligands that form
multiple chemical bonds in a ring structure [34]. Chelants react with metals
in ionic form only, not in a free metallic state.
Chelation may be defined as achieving an equilibrium between a metal ion
and a complexing agent, characterized by the formation of more than one bond
between the metal and a molecule of the complexing agent and resulting in a
ring structure incorporating the metal ion.
Process Parameters--
¦ Effect of Other Metal Cations--A stability constant measures the
affinity of a metal for a particular chelant. The greater the
affinity, the greater its ability to displace other chelated
metals. This preferential chelation occurs at a thousandfold
stability difference between metals [35]. Naturally occurring
soil-bearing metal cations compete for the chelating agent with the
contaminant metal ions requiring excessive chelate quantities.
However, proper pH control and chelate selection may minimize this
effect.
26
-------
Effect of Other Anions --Anions have little effect on chelation.
However, sulfide anions form very stable metal sulfide complexes,
which may be useful in regenerating spent chelation solutions.
Soil Classification--Process problems resulting from the silt/clay
soil fraction have been encountered in previous efforts to extract
lead from soil [36]. Solid/liquid separation difficulties and
failure to decontaminate the silt/clay fraction can be eliminated by
classifying soil into its constituent fractions before or during
chelation. Remediation methodology and equipment can be adapted to
each classified fraction.
Temperature--Temperature has a negligible effect on chelation.
Chelant-metal complex stability decreases one order of magnitude per
55°C increase [35].
Ionic Strength Effect--An ionic equilibrium exists within the
chelant-metal complex. Although a large concentration of ions not
participating in chelation lowers the complex stability, the effect
is negligible [35],
Chelant Concentration*-The amount of chelant needed to react with a
unit weight of a specific metal is provided in manufacturers'
literature; this quantity should be verified by laboratory tests
[35]. For continuous processing of soils, additional considerations
in determining chelant quantity are chelant solution viscosity and
the amount of chelant needed to drive the reaction to completion.
Chelation Duration--If the objective is to chelate the maximum
amount of metal, then empirical determination is necessary to obtain
the reaction duration (retention time).
Soil Loading--The chelating solution-to-soil ratio must be high
enough to allow proper mixing. However, as the ratio increases,
reactor size, number of reactor vessels, or both increase. If the
chelant-soil mixture reaches chemical equilibrium, soil loading must
be balanced with spent chelant removal and fresh chelant
introduction rates.
£H--pH is one of the most important parameters of the system. Both
metal cation and chelating agents are influenced by hydrogen ions.
Hence any change in pH affects the equilibrium of the system [35].
Since stability constants are pH dependent, an adjustment of
solution pH may favor the formation of a preferred metal complex.
For example, pH 7 to 9 favors lead (II) chelation over the generally
more stable Fe(III), so contaminated soil may be treated without
significantly extracting the ubiquitous iron.
27
-------
Specific Experience--Metal chelation research has examined metals to soil
binding and metal availability for removal of metal from the soil. Soil
treatment research has focused on in situ metals chelation with low
concentration, mild extractants. Limited extraction work on excavated soil
has yielded encouraging metal reduction results, but has encountered soils
handling problems. DTPA sludge extractions by Silviera and Sommers yielded
maximum removals of 50, 29, 40, and 30 percent for total Pb, Zn, Cd, and Ca,
respectively [37]. Brown, et al., reported the percentage of extractable
metals for removal in sludge-treated Padina soil was as high as 105, 84, 56,
178, and 46 percent for Pb, Zn, Ni, Cd, and Ca, respectively [38].
In EDTA chelation experiments for in situ treatment Connick, et al.
preadsorbed metal salts onto Typic Hapludults (fine to coarse loamy) soil
contained in columns and rinsed with 0.144M EDTA, achieving 63, 93, 94, 100,
and 82 percent removal of Pb, Zn, Ni, Cd, and Cu, respectively [39,40].
During soil leaching studies, extraction of preadsorbed clays by Farrah and
Pickering showed EDTA effectiveness on the strongly binding clay fraction
[41]. Some researchers assert that metal-soil binding changes with time until
an equilibrium is established [38,40]; hence preadsorbed soils used in the
previous extraction studies may not be representative of "mature" NPL soils.
Ellis and Fogg used an EDTA/hydroxylamine/citric acid sequential extraction
for in situ remediation of Western Processing, Inc., NPL site soil, reducing
Pb, Ni, Cd, Cu and Cr by 96, 22, 100, 75, and 52 percent, respectively [34].
Their multiagent extraction was more effective than a single-step EDTA
chelation, because a greater range of metal binding mechanisms was vulnerable
to release.
Other chelants reduced lead content in soil at Church of Cod in Leeds,
Alabama, by 95 percent with ammonium pyrolidinecarbodithioate (APOC) [36]; and
EPA reported that "NTA did not work as effectively as EDTA" in chelating lead
from the soil at the Lee Farm in Woodville, Wisconsin during laboratory
studies [42,43].
Recent pilot-scale chelation studies on excavated soils have produced
promising results. The USEPA Releases Control Branch, utilizing 13 to
16 percent EDTA chelant, removed 94 to 97 percent of total lead from Church of
God soil using the 4 to 5 ton/hr capacity screw extractor. At the Lee Farm,
USEPA Region V reduced gross lead contamination below the EP toxicity limit of
5 ppm leachable lead in laboratory-scale EDTA chelations. However, during
production-scale treatment, the broken battery casing fraction alone was
decontaminated below EP Toxicity requirements [42,43].
Soil-handling problems at both sites included:
¦ Clogging of plate and frame filter presses due to silt and clay;
¦ Plugged pumps, worn augers, and difficulty in handling sands;
¦ Large quantities of chelation solution carryover into rinse tanks;
and
¦ Solid/liquid separation of silt and clay between process steps.
28
-------
To eliminate some of the problems encountered at the Lee Farm,
Enviresponse, Inc. (EI) under USEPA Emergency Response Team (ERT) auspices
classified Lee Farm soil into three fractions (0.25 in.; 100 um-0.25 in.;
<100 um) before laboratory EDTA chelation. They achieved 700 ppm residual
total lead in the 100 um-0.25 in fraction, a 95 percent reduction, while
maintaining EP toxicity values within limits [17]. By adjusting the EDTA
solution to pH 7, thereby maintaining a high stability constant for lead over
iron, these researchers chelated little Fe(III) in the high-iron-bearing soil.
Heavy Metals Extraction Using Acids--
Heavy metals can be extracted from soil by using acid as an extraction
agent. This is a common technique for extracting minerals from ores. The
heavy metals are separated from the acid solution either by precipitation or
ion exchange.
Process Parameters--
¦ Extractant Type--Factors to consider in choosing an acid are
effectiveness, safety, disposal, and cost.
¦ Extractant Concentration--Acid extractant concentrations have varied
greatly (e.g., 0.001M HN03 to concentrated HN03) [41,44]. If
the release of metals occluded in coprecipitates as oxides and
sulfates is desired, then higher acid concentrations are necessary.
The literature reported that extractant concentrations vary greatly;
therefore, experimental data are needed to determine the appropriate
concentration to obtain a desired reaction product.
¦ Soil Loading--As with soil chelation, the extractant-to-soil ratio
should allow for intimate mixing. The soil loading should be low
enough to allow maximum metal extraction at a particular extractant
concentration.
Specific Experience--Singh and Narwal [44] state the following order of
extraction performance for removing metals from sewage sludge-treated soil:
HNOj > Aqua Regia > HC1 > NH^OAc (pH 4.8). However, different
concentrations used in this study make acid comparisons difficult. A
treatment study at the Celtor Chemical Works site in Hoopa, California
utilizing sodium glutonate solution, EDTA, acetic acid, hydrochloric acid, or
hydrochloric acid/hydrogen peroxide, found that "none of the extractants were
capable of producing a soil below cleanup level for all metals" [45]. This
study reported that lead removals were poor for hydrochloric acid and acetic
acid extractants, although lead removals were up to 44 times greater for hot
HCl vs. ambient HC1. The removal pattern for HC1-H202 was similar to the
pattern for HCl. On the other hand, an ammonium carbonate-fluorosilicic acid
extraction of the Lee Farm classified soil (100 um to 0.64 cm fraction) was
performed by Cole at the U.S. Bureau of Mines in Rolla, Missouri. This
process reduced total soil lead in this fraction to 500 to 800 ppm--a 94
percent reduction from an average initial lead concentration of 10,749 ppm
[17] .
29
-------
The Muller leaching process extracts heavy metals from contaminated
dredged materials, sludges, combustion residues and soils. After the heavy
metals are extracted with HC1, the solids are separated from the filtrate.
The heavy metals are removed using hydroxide and carbonate precipitation. The
remaining filtrate contains
-------
For a single batch extractor, contaminant-free solvent is sprayed until
the bottom solvent shows no traces of contaminant and the extraction can be
considered total. The process is slow and requires large amounts of solvent;
the rate of extraction decreases with contaminant concentration.
To overcome these disadvantages, a battery of extractors can be operated
in countercurrent extraction. The more fully extracted soil is leached with
virgin solvent; the raw contaminated soil is the last in the extraction line.
Immersion Extraction--
For low-solubility contaminants, fine soils like clay and silt, or soils
with a very low residual contaminant content, the leaching process is
unacceptable due to slow mass transfer rates. For these cases the solid is
dispersed into the liquid in an immersion extraction.
In its simplest form, an immersion extractor is an agitated tank filled
with the solvent, in which the soil is suspended and thoroughly mixed. When
the extraction equilibrium has been reached, the agitation is stopped and the
solid is allowed to settle. The solvent is drained and fresh solvent can be
used for a second step extraction. The countercurrent extraction concept
described for leaching extraction also applies for immersion extraction.
Soil-Solvent Separation--
Soil-solvent separation can be a simple unit operation or a cumbersome
series of unit operations. For coarse, easy-draining soils such as gravel and
sand, the solvent is just drained from the soil. For hard-to-settle fines,
such as clay or silt, the operation will require mechanical solid-liquid
centrifuges.
Residual Solvent Removal--
Granular solids retain liquids because of surface adherence forces and
interstitial surface tension forces. The higher the viscosity and surface
tension of the liquid and the smaller the granules of the solid, the more
solvent is retained in the solid bed. Selected solvents are expected to have
low viscosity and surface tension, which will reduce liquid retention. Fine
soils, high surface adsorption materials, or colloidal suspensions tend to
retain large amounts of solvent.
The most easily treated soil is a coarse sand which will retain, after
free gravity drainage, approximately 2 to 3 weight percent solvent. For finer
grained soils, centrifugation or thermal desorption may be necessary to obtain
low solvent residuals.
Solvent Displacement--
Most, if not all, of the organic solvents are undesirable contaminants in
soil and, regardless of the cost of the lost residual solvent, must be
eliminated from the soil before reburial. Some examples of elimination
processes are solvent displacement, gas or vapor stripping, and steam
stripping.
31
-------
Solvent displacement is another solid-liquid extraction process where the
new solvent is nontoxic and is left in the soil. The initial extraction
solvent must be totally miscible with the displacement solvent. The least
expensive and most nontoxic displacement solvent is water. Unfortunately,
most good organic solvents (e.g., hydrocarbons or halogenated hydrocarbons)
are not soluble in water, and this method cannot be applied. Alcohols,
ketones, and esters are classes of solvents with high miscibility with water;
consequently, displacement of the residual solvent with water is possible.
Process considerations and equipment used for solvent extraction also apply
for this displacement process. Gas, vapor stripping and steam stripping are
processes similar to volatile organic contaminants stripping, described in
detail later.
Solvent Recovery--
Environmental and economic considerations require solvent recovery and
reuse of the recovered solvent. As initially discussed, to obtain a high
level of solvent recovery, a recommended solvent must have a relatively low
boiling point quite different from the contaminant boiling point. The most
used and recommended solvent recovery method is distillation. The recommended
solvent need not be totally contaminant free. Small amounts of contaminant
may be recycled in the soil extraction.
Another possible, though unlikely, solution for solvent recovery is a
chemical reaction of the contaminant with the formation of a precipitate, an
immiscible phase, or a nontoxic component. In these cases a precipitate can
be separated by filtration and a nonmiscible phase by liquid-liquid
separation; the nontoxic compound can be left to accumulate in the recycled
solvent until its concentration interferes with the extraction process.
Related Experience
Pertinent experience in commercial solid-liquid extraction applied to
large amounts of solids includes ore, tar sand, and sugar beet extraction. In
all these processes, the extractor contributes substantially to the capital
and operating cost of the whole plant. Consequently, a substantial
engineering effort has been put into developing continuous extractors.
Theoretically, continuous extraction can be operated in co-current,
cross-current, or counter-current modes. Consideration of the thoroughness of
extraction and solvent consumption make the counter-current extraction the
only commercially feasible option.
Starting from the battery of extractors concept, Dravo Corporation
developed the Rotocel Extractor. In this extractor (Figure 2), the material
to be extracted is fed continuously as a slurry with the extraction solvent or
as a dry feed to sector-shaped cells arranged around a horizontal rotor. The
cells have a perforated base to permit the solvent to drain into stage basins,
from which, on the countercurrent principle, it is pumped to the next cell.
In the last cell, where fresh solvent is supplied, an extended drainage period
is provided (by allowing a proportionately larger arc of the rotary motion for
this cell); thereafter, the extracted solids are dumped. In addition to being
32
-------
Figure 2. Rotocel percolation extractor. Courtesy of Dravo Corporation.
Reprinted from Encyclopedia of Chemical Technology, 3rd ed. Vol. 9
by Kirk-Othmer; Copyright ©1979. Reprinted by permission of
John Wiley and Sons, Inc.
33
-------
filtered by the bed of material being extracted, the fines are filtered over a
tent screen before complete solvent removal. Rotary extractors similar in
principle to the Rotocel are offered by other equipment manufacturers.
Filtration of the fines over a bed of coarse material has been claimed to
achieve solvents with less than 5 ppm suspended solids [48].
Another continuous extractor is the Endless-Belt Extractor; its principle
operation is similar to the Rotocel. Two key parameters, extraction time and
percolation rate, determine belt speed and the required drainage area,
respectively. Since bed height is virtually fixed by the mechanical design of
the extractor, these parameters control the plant capacity. A low percolation
rate could make the required drainage area prohibitively large. Solvent,
which can be fed by spraying or simply from overflow weirs, may be used in a
simple counter-current manner or, where the percolation rate is high, may be
recycled internally to improve the approach to equilibrium [48].
The Lurgi Frame-Belt Extractor (Figure 3) has a two-tier system in which
the solid material travels the length of the extractor while being extracted
in an upper series of compartments (frame buckets), with the perforated
endless belt serving as a false bottom. The bed is then partially drained of
solvent and discharged into a lower series of compartments. There extraction
continues with an increasingly leaner solvent until reaching a final drainage
zone before discharge of the exhausted solids [48].
The De Smet Belt Extractor (Figure 4) uses a single endless belt to hold
the material being extracted. The risk of solvent migration is minimized by
rakes that penetrate the upper 150 mm of the bed (overall bed height 1.3 to
1.8 meters) to form ridges of solid material at intervals. The rakes also
break up the upper layer of the bed to maintain steady percolation
conditions. The belt moves discontinuously, providing a clearly defined
extraction period followed by a drainage period [48].
The immersion extractors have the ability to handle fines and to extract
materials with low diffusion rates. This type of process is used for the
extraction of sugar beets, oil seeds, or trace pigments and pharmaceuticals
from plant materials. Continuous immersion extractors were originally
constructed in tower forms, and such designs have maintained an important
place in the sugar industry.
The BMA Diffusion Tower has a central shaft fitted with a series of
inclined plates that direct movement of the solid material. The tower shell
is also fitted with a series of staggered guide plates that serve the same
purpose. Another tower extractor, in this case designed and built by Wolf,
also employs the principle of wings attached to the central shaft to transport
the solid material to be extracted up the tower. In both cases sugar beets
are fed to the base of the tower. The towers are commonly 10 to 15 meters
high; different capacities are achieved by variations in tower diameter. In
either form of construction, power consumption for a 5.5 meter diameter tower
(capacity: 3,000 metric tons of beets per day) is about 40 kW [48].
34
-------
- - 9< + X'
Extracted solids
discharge
Solvent
recycle
Rich miscella
discharge
Figure 3. Lurgi frame belt extractor. Courtesy of Lurgi Umwelt und
Chemotechnik G.m.b.H. Reprinted from Encyclopedia of Chemical
Technology, 3rd ed. Vol. 9 by Kirk-Othmer; Copyright ©1979.
Reprinted by permission of John Wiley and Sons, Inc.
A
Solids feed
h
^
:7t^7z
&
* rhr
e-
222
&
~ Extract
Be't wash
r,
t
Solvent
Discharge
Figure 4. DeSmet continuous-belt extractor. Courtesy of Extraction DeSmet, S.A.
Reprinted from Encyclopedia of Chemical Technology, 3rd ed. Vol. 9 by
Kirk-Othmer; Copyright ©1979. Reprinted by permission of
John Wiley and Sons, Inc.
•35
-------
The De Danske Sukkerfabriker (DDS) diffuser extractor (Figure 5) may be
regarded as a tower extractor with its axis turned about 80°. The extractor
is normally installed at a one (vertical) to seven (horizontal) slope, and a
double screw in the housing is used to transport the solids. The operating
temperature is reached by employing jacket heating, thus avoiding the
requirement for preheating. The dimensions of the DDS diffuser and its power
consumption are, broadly speaking, similar to those of the tower
extractors [48].
The use of these immersion extractors is contingent upon the ability to
transport solids without excessive back mixing. They need less space than
percolation extractors and lower power for the band drive and liquor
circulation [48].
The need to improve the desired product removal yield and to reduce the
contact time led researchers to introduce extra energy into the extraction
process. The most successful attempt seems to be the use of ultrasonic energy
along with immersion extraction. Using acetone as a primary extraction
solvent with heptachlor epoxide, contaminants were extracted in the laboratory
with ultrasonic waves; results were better than with the simple solvent
extraction [49]. Ultrasonic energy plus slow stirring enhancement was used
for removing the bitumen from tar sands with good results. Solvent extraction
pilot study results showed that ultrasonic energy plus slow stirring achieved
78 percent bitumen removal after 30 seconds, while stirring alone achieved
only 63 percent removal after 4 hours [50].
Procedures for Contaminant Removal from Soil
Nonvolatile Organic Contaminants - -
Nonvolatile organic contaminants can be hydrophilic or hydrophobic
organics. Both types of these organics can be handled by solvent extraction.
Commonly found hydrophobic organic compounds at NPL sites are pesticides,
heavy oils, and grease. Commonly found hydrophilic organic compounds at NPL
sites are phenols, methylene chloride, and aldehydes.
Process Parameters*-
Physical Properties of Solvents--Low surface tension increases
wetting of the soil and provides for better contact, whereas low
viscosity improves diffusion of contaminant into the solvent. Low
solvent density reduces the mass of solvent held up in the soil
being extracted. The vapor pressure of the solvent should be
sufficiently low so that the storage and extraction operations can
be carried out at atmospheric or low pressure. The solvent should
be nontoxic and nonhazardous.
36
-------
PucnO
-e-
- e
&
• 1 H«»«« '
<3-- ^
Sow*
tfc-
bJJ '0Q- • ' GO ¦ -' O
pyfT*p I PuiT>P ^ ^
| Heal McMnge' |
t_/C\_j 1 ) '•.
Solid*
ditch*?*
Heat excwt*' | Ufa!
L
Extract
Spin* v>»v«nt outlet
« a/c (s]]ro Atomized
John Wiley and Sons, Inc.
37
-------
¦ Extraction Stapes--More than one stage is required. The residence
time in each stage should be long enough to achieve system
equilibrium.
¦ Selectivity--For aqueous extraction varying the pll gives some
control over selectivity. With organic solvents, greater
selectivity can be obtained by choosing a single solvent or by using
a mixture of solvents.
¦ Solid-to-Extraction Solution Ratio--A ratio of one part solid to one
part extraction solution is preferred to minimize the treatment of
extractant. However, a ratio of two-to-five is a more practical
range.
¦ Temperature--The choice of the solvent determines the processing
temperature that is optimal for mobilizing the contaminants.
Certain solvents operate best at low temperatures, others at higher
temperatures. Furfural as a solvent is used at relatively high
temperature, usually in the 150° to 250°F range. Nitrobenzene is a
solvent used at relatively low temperature (in the vicinity of
50°F). Both of these solvents are extensively used in the petroleum
refining process.
Specific Experience--Removal of organic contaminants from soil has been
limited to laboratory techniques directed toward soil analysis rather than
directed toward soil decontamination. Specific laboratory apparatus, such as
SOXHLET and POLYTRON, is used; the extraction time is extended beyond any
commercially acceptable period (e.g., 120 to 240 minutes) [3].
Experiments with two nonmiscible solvents, water (polar) and kerosene
(nonpolar), have been successful in transferring the contaminant to the
nonpolar solvent, but end up with high solvent content in the cleansed soil
(e.g., 20 to 25 percent) [51,52]. All these experiments were conducted with
high solvent-to-soil ratios.
M.B. Saunders [53] describes pilot-scale studies of the Soilex process
for removing PCBs from soil. A mixture of kerosene and water was the solvent
of choice. A ratio of water-to-soil of 3 together with a kerosene-to-soil
ratio of 3 resulted in a slurry having good hydraulic mixing characteristics
and yielded a PCB leaching percentage of 84 percent.
The pilot plant consisted of three mixing stages, operated in a
counter-current mode. Soil and water were added to stage 1 and clean kerosene
to stage 3. Each mix tank had a 200 liter capacity and was mixed with an
air-driven agitator. Sampling during the tests showed that equilibrium
extraction was achieved in 90 minutes. Kerosene was recovered from the
kerosene-water solvent by batch distillation. Kerosene losses in the soil
were estimated to be about 25 percent of the kerosene charged. Solid-liquid
separation in the pilot plant was by settling and decantation. Kerosene
losses were estimated to represent only 2 to 5 percent of the total operating
cost. The author reports that the capital cost for solvent extraction was
about 50 percent of that for incineration.
38
-------
The CF Systems Corporation of Cambridge, Massachusetts is currently
marketing a system that employs propane as the extractant [54]. Propane at or
near its "critical point" is used to contact a 50 percent by weight
sludge-water slurry in a reactor. Organic contaminants in the sludge dissolve
in the "critical fluid" phase and thus are extracted. Typically, 99 percent
of the organics in the sludge are extracted. The "critical fluid" containing
dissolved organics is then decompressed. The solvent flashes into a vapor.
The organics remain as a liquid. The solvent is recorapressed and cooled and
recycled to the extraction step as a "critical fluid."
The system vendor indicates that three units will go on stream in 1988.
Two units will be fixed installations, and the third will be a skid-mounted
mobile unit that can be moved from site-to-site. The mobile unit will have a
capacity of 1,000 barrels/day of a sludge-water slurry.
The Basic Extraction Sludge Treatment (B.E.S.T.) [55] process uses
triethylamine (TEA), a flammable solvent soluble in water below 65°F and
insoluble above 65°F, to extract oil from oily sludges. The sludge and
solvent are mixed in an extractor at temperatures below 65*F. The water with
dissolved solvent and oil is separated from the solid by centrifuge. The
water is heated, and solvent with the oil is separated from the water. The
solvent is then sent to a stripping column where solvent is recovered and oil
discharged. Hazardous oils and heavy chemicals are recovered and not
destroyed by this process. These must be disposed. The B.E.S.T. process is a
complex process requiring high degrees of sophistication for operation.
AIR STRIPPING
General Process Considerations
Air stripping is normally used to remove VOCs from soil. To strip
volatile organic compounds (VOCs) from soil, the VOC must be vaporized. The
stripping may be done at essentially ambient temperatures, or heat may be used
to increase the rate of vaporization. Air or steam is the most likely
stripping gas. VOCs are removed from a circulating air stream by use of
adsorption or combustion. When steam is used as the stripping medium it can
be removed by condensation leaving a relatively concentrated vapor of VOC
for disposal.
Process Unit Description
In general, any system that is employed in drying solids is applicable to
stripping VOCs from soil. These systems consist of:
¦ A gas/vapor solids stripping device;
¦ A stripping gas circulating device; and
¦ A means to remove, recover, or destroy the VOCs in the stripping gas.
39
-------
When treating soils that adhere and form large particles (i.e., are
fine-grained and tend to agglomerate), the following items of equipment may be
used for stripping/drying:
¦
Holo-flite screw
Rotary kiln/dryer
¦
Hereschoff furnace
When processing granular free-flowing sandy soils, which disperse easily,
fluid bed combustors of the circulating or bubbling type are applicable.
Related Experience
Holo-Flite TM Screw--
The Holo-Flite Screw is identified by name only because it has been
specifically tested on soils; however, any similar device would perform as
well. Testing performed for the U.S. Army Toxic and Hazardous Materials
Agency (USATHAMA) of the removal of VOCs from soil using a Holo-Flite Screw
with induced airflow through the trough showed a removal efficiency of
99 percent [56].
The system consisted of a jacketed trough which housed a double-screw
mechanism (Holo-Flite.) The screws were 7 inches in diameter and ran the
entire length of the trough. The screw shafts and flights were hollow to
accommodate circulation of the heat transfer liquid (i.e., hot oil.) The hot
oil flowed through the flights in a direction concurrent to the movement of
the soil. The oil entered the unit at the soil feed end of the system
processor, circulated through the flights, and flowed back through the shaft
to exit the unit at the same end that it entered. The trough jacket also
circulated hot oil, providing additional heat exchange.
The screws were driven at various rotational speeds via a chain drive
connected to the gear reducer located beneath the conveyor. The continuous
action of the screws promoted forward movement of the soil through the
trough. The screws were set in the trough so that the flights of the two
screws intermeshed to break up the soil and improve heat transfer.
Reported process operating conditions are:
Soil Discharge Temperature
50cC to 150'C
¦
Soil Residence Time
30 to 90 minutes
Air Inlet Temperature
Ambient (20*C) to 90°C
Circulating Oil Temperature
100°C to 300°C
AO
-------
Based on the reported test results, this technology appears to provide
significant contaminant removal and merits additional investigation on
specific contaminated soils. The system has the following advantages:
¦ Mobile units are available.
¦ The units can be designed for energy efficiency because of the good
contact between the soil and the flights and the relatively low gas
flowrate,
¦ The low gas flowrate reduces the cost of gas treatment facilities.
¦ Reported soil discharge temperatures are moderate (50°C to 150°C),
which should further reduce processing costs.
¦ The unit should be capable of processing all types of soil. Soils
high in clay could be a problem, requiring the addition of gravel
that would be removed by screening after treatment and recycled.
A disadvantage of the system is the size of the equipment and the long
holding times limiting throughput. This possibly could limit the size of a
site applicable to the technology and increase unit processing cost,
particularly labor costs.
Rotary Kiln/Dryer--
A rotary kiln is normally used in waste processing as an incinerator.
However, if the purpose is to remove VOCs without destroying the character of
the soil or to operate at lower temperatures to avoid fouling the walls of the
kiln, the temperature in the kiln can be controlled at between lOO^C and 400QC.
Rulkens, et al, [11] describe a facility in the Netherlands for cleaning
5,000 tons of soil contaminated with hydrocarbons using a two-stage rotating
drum evaporator. Ecotechniek has developed a full-scale system for heating
the soil to 200°C to 3G0°C and releasing the burned vapors in an afterburner
at 800°C,
The rotary kiln thermal treatment to remove contaminants from soil by
evaporation uses direct or indirect heat transfer to the soil. Direct heat
transfer requires large volumes of gas (1 to 2 cubic meters/kg soil) to
provide the energy for raising the temperature of the soil. Indirect heating
requires one-third less hot combustion gas. The system has the following
advantages:
¦ Can be designed to be mobile;
¦ Can process any type of soil, but special processing is required for
soil with a high proportion of clay; and
¦ With indirect heat transfer, the airflow can be relatively low.
41
-------
The following are the disadvantages of the system:
¦ With direct heat transfer, the gas flow will be high, requiring
expensive gas treatment facilities;
¦ With indirect heat transfer, a very large heat-transfer surface
(rotary kiln drum) is required;
¦ Unless extensive heat conservation is provided, the process will
expend large amounts of heat energy;
¦ Rotary kilns are difficult to seal and since the contaminants are
not destroyed in the kiln, it must be operated at negative pressure;
and
¦ Soil containing a high concentration of fines may not be suitable
for processing, because prevention of fines entrainment is
impossible.
The Hereschoff Furnace--
The Hereschoff furnace is a proven technology used in drying clays and
regenerating activated carbon and other solids. To prevent binding and
possible breakage of the flights, feed pretreatment to reduce the particle
size is required. The pretreated soil, containing water and contaminants, is
fed in at low temperature to the center of the top tray, gradually moved by
the rotating flights to the outer edge, and falls to the second tray. These
rotating flights gradually move the soil to the center, where it falls to the
third tray. Access ports are provided on each tray.
The process is repeated with the soil moving back and forth on the trays,
falling off the bottom tray of the furnace, and being transferred to
disposal. Fired heaters produce hot gases that are introduced into the
furnace under the trays. For flexibility, many entrance ports are provided.
The point for introducing the hot gases is optional, as is the number of
trays. Trays below the point where the hot flue gas is introduced can be used
for cooling the soil by introducing air at ambient temperature. The gas moves
countercurrent to the soil, and the flights cause the soil to roll as it is
moved, thus exposing new surfaces to the gas.
Special precautions are needed when using this technology for treatment
of soil containing hazardous VOCs. The unit must be airtight or operate under
a slight vacuum. The gas is moved through the unit by an induced-draft fan.
The type of gas treatment facilities to be provided depends on the
contaminants removed and gas treatment may not be needed in some cases.
The system has the following advantages:
¦ Temperatures to 500*C are attainable.
42
-------
¦ With a sufficient number of trays and proper operation, a reasonable
energy efficiency is attainable.
¦ It is a demonstrated technology. However, whether it has been used
to strip VOCs from soils is not known. It is used to burn
hydrocarbons from clay.
¦ With reasonable pretreatment, all soils can be processed.
This system, however, has the following disadvantages:
¦ A transportable unit for use in treating soil would be difficult to
design.
¦ Many trays would be required to achieve energy efficiency.
Circulating Bed Combustor--
The circulating bed combustor was developed for the combustion of
high-sulfur fuel to produce steam. It was developed as a modification of the
bubbling fluidized bed combustor to achieve substantially higher system
volumetric efficiencies. The technology should be applicable, given certain
modifications, to stripping VOCs from soil with a gas. The technology would
be applicable to free flowing feedstocks (sand or silt).
The incoming gas is preheated sufficiently to heat the soil to the
required temperature. The hot gas is passed through a distributor at a
velocity sufficient to entrain the soil. Contaminated soil is added above the
distributor, entrained, and heated by the hot gases. The entrained soil is
separated from the hot flue gases in a cyclone and recirculated into the bed.
A solids draw-off from the cyclone maintains the material balance in the
system. High clay soils would require significant premixing with sand before
feeding to avoid agglomeration in the bed.
The major advantage of this process is its very high volumetric
efficiency. Its major disadvantage is that it is limited to free flowing
feedstocks.
Bubbling Bed Combustor--
A bubbling bed is made of a granular material (sandy soil) through which
a gas is blown from a distributor at the bottom of the bed. The gas rate is
controlled so that the bed material bubbles just to the point of incipient
fluidization, but not sufficiently to lift solids from the bed. This
technology can be used to remove VOCs from sandy soil by preheating the gas
sufficiently to raise the temperature of the bed material so that the VOCs
adsorbed on the solids are vaporized. The contaminated soil, which becomes
the bed material, is fed in at the top of the bed and is withdrawn from the
bottom. The gas leaving the top of the bed is withdrawn from the freeboard
above the bed and appropriately treated before venting it to the atmosphere.
43
-------
The residence time can be controlled by bed height or soil feedrate. The
bed temperature is controlled by the temperature of the gas entering the bed.
The advantage of this technology is the lower energy required for gas
circulation. The major disadvantage is that it is limited to free-flowing
feedstocks. High clay soils would require significant premixing with sand
before feeding to avoid agglomeration in the bed.
Procedures for Contaminant Removal from Soil
Volatile Organic Compounds--
Process Parameters--
¦ Heat--Although very little testing has been done in this area, the
soil will have to be heated if VOCs are to be removed to acceptable
levels by gas stripping. The soil will need to be heated to between
100° and 400°C, depending upon the vapor pressure of the VOCs to be
removed and the adsorptive forces binding the organic molecule to
the soil particle. The addition of recuperative heat exchangers
will reduce the amount of fuel required.
¦ Stripping Gas--Gas flow can be accomplished by blowing the air
through or over the soil under pressure or by using an induced-draft
fan to pull the gas through the soil, under a vacuum. Any gas may be
used as the stripping agent. Practical considerations tend to limit
the choice to air or steam. Which should be chosen will depend on
the type of soil to be treated, the type of VOC to be removed, the
site location, and the objectives of the procedure.
¦ Post-treatment--Stripping of VOCs from soil with a gas at relatively
low temperatures will produce a gas stream containing VOCs that must
be removed or destroyed before the gas can be vented to the
atmosphere. Removal of a condensible from a noncondensible by
condensation is difficult and inefficient. For this reason, if the
stripping agent is a gas such as air, removal and concentration of
the VOCs by adsorption, or destruction by after-burning, would
probably be required in many cases. However, if the stripping
medium is a condensible such as steam, condensation followed by an
appropriate treatment procedure such as gravity separation,
biological oxidation or adsorption, or a combination, would be
possible. There are four air gas treatment options: a secondary
combustion chamber, catalytic oxidation, gas scrubbing, and
adsorption.
¦ Soil Preparation--Some form of feed pretreatment is required.
Pretreatment may be merely prescreening to remove the large material
such as boulders and logs. It is reasonable to assume that almost
all soils will contain fines that will be entrained in the gas.
Provision must be made for the removal and adequate handling of
these fines. Consideration must be given to the possibility that
the VOCs may well be readsorbed on the surface of the fines if the
gas is allowed to cool before the fines are removed.
44
-------
¦ Soil Tvpe--Silts and clays provide much more surface area per unit
mass than sand and rock. In addition to a higher external surface
area, some of this material may be porous, providing additional area
and pores for adsorbing the VOC molecules. The wide range in
particle size and density of most soils will provide severe problems
for most stripping technologies and may well rule out the use of
some. Soil high in clay will be particularly difficult to treat.
Special provisions to prevent agglomeration in the bed will be
required.
45
-------
REFERENCES
X. U. S. Environmental Protection Agency. Solving Hazardous Waste
Problems. EPA's RCRA Program. EPA/530-500-86-037, November 1986.
2. Office of Federal Register, Code of Federal Regulations 40, Parts 100 to
149, July 1, 1986.
3. U. S. Environmental Protection Agency. Proposed Sampling and Analytical
Methodologies for Addition to Test Methods, SW-846, 2nd Edition,
4. ORG Handbook of Chemistry and Physics, 65th Edition. CRC Press, Inc.
Boca Raton, FL, 1984-1985.
5. Chemical Engineers* Handbook, 5th Edition. McGraw-Hill, NY, 19/3.
6. The Condensed Chemical Dictionary, 10th Edition. Van Nostrand-Reinhold,
NY, 1981.
7. Sax, N.I., et. al. Dangerous Properties of Industrial Materials, 5th
Edition. Van Nostrand-Reinhold, NY, 1979.
8. Verschueren, K. Handbook of Environmental Data on Organic Chemicals, 2nd
Edition. Van Nostrand-Reinhold, NY, 1983.
9. The Merck Index, 10th Edition. Merck and Co., Railway, NJ , 1983.
10. U. S. Environmental Protection Agency, Chemical Emergency Preparedness
Program, Interim Guidance. 9223.0-lA, Revision 1, November, 1985.
11. Rulkens, W. H., J. W. Assink, and W. J. Van Gemert. Project B: On-site
Processing of Contaminated Soil. In: Contaminated Land Reclamation and
Treatment. M. A, Smith, ed. Published in cooperation with NATO Committee
on the Challenges of Modern Society. Plenum Press, New York, 1985,
12. Rulkens, W. H., J. W, Assink, and W. J. Van Gemert. Development of an
Installation for On-Site Treatment of Soil Contaminated with Organic
Bromine Compounds, Netherlands Organization for Applied Research,
Division of Technology for Society, Apeldoorn, The Netherlands.
13. J. W, Assink. Extractive Methods for Soil Decontamination; A General
Survey and Review of Operational Treatment Installations. In:
Proceedings of the First International TNO Conference on Contaminated
Soil, Ultrecht, Netherlands. November, 1985.
46
-------
14. Heimhard, H. J. High Pressure Soil Cleaning Process for Cleaning
Polluted Soil in Berlin. In: Proceedings of the Second International
TNO Conference on Contaminated Soil, Hamburg, Federal Republic of
Germany, April, 1988.
15. Sonnen, H. D., and S. Klingebiel. Experience Gained with a Soil
Decontamination System in Berlin. In: Proceedings of Second
International TNO Conference on Contaminated Soil, Hamburg, Federal
Republic of Germany, April, 1988.
16. EWH Recycling Gmbh-Alben-Brietenburg, Mobile Bodenwaschanlage, Lagerdorf,
Federal Republic of Germany, 1988.
17. Rayford, R., R. Evangelista, and R. Unger. Lead Extraction Process.
Draft Report, EPA Contract No. 68-03-3255, U.S. Environmental Protection
Agency, Emergency Response Branch, Edison, NJ, 1986, 63 pp.
18. Scholz, R., and J. Milanowski. Mobile System for Extracting Spilled
Hazardous Materials from Soils. Report, EPA Contract No. 68-03-2696, U.
S. Environmental Protection Agency, Office of Research and Development,
Cincinnati, OH, 1982.
19. Traver R. CERCLA BDAT SARM Preparation and Results of Physical Soil
Washing Experiments. Vol. I. Report, Contract No. 68-03-3413, U.S.
Environmental Protection Agency, Hazardous Waste Engineering Research
Laboratory, Cincinnati, Ohio, 1988, 89 pp.
20. Coulson, G. R. Hot Water Process for the Extraction of Oil from
Bituminous Sands. U. S. Patent No. 2,968,603, 1961.
21. Texas Research Institute, Inc. Test Results of Surfactant Enhanced
Gasoline Recovery in a Large-Scale Model Aquifer. American Petroleum
Institute Publication 4390, 1982.
22. Van Luin, A. B., and H. Warner, Treatment of Polluted Water from the
Clean-Up of Contaminated Soil. Rijkswaterstaat, Institute for Inland
Water Management and Wastewater Treatment, Telyrtad, Netherlands.
23. Venhataramani, E. S., R. C. Ahlert, and P. Corfo. Biological Treatment
of Landfill Leachates. CRC Critical Reviews in Environmental Control,
14(4): 333-376, 1984.
24. Ahlert, R. C., and D. S. Kosson. Remediation of an Industrial Dump Site
- A Case History. EPA-600/9-86/022. In: Proceedings of the 12th
Annual Research Symposium, 1986.
25. Dempsey, B. A. Removal of Naturally Occurring Compounds by Coagulation
and Sedimentation. CRC Critical Reviews in Environmental Control, 14(4):
311-331, 1984.
47
-------
26. Freeman, H. M., and E. T. Oppelt. Innovative Thermal Process for
Hazardous Waste Treatment and Destruction. EPA/600/D-85/169. Thermal
Destruction Branch, Alternative Technologies Division, Hazardous Waste
Engineering Research Laboratory, Office of Research and Development,
U. S. Environmental Protection Agency, Cincinnati, OH, 1985.
27. Zepp, R. G., G. L. Baughman, and P. F. Schlotzhauer. Comparison of
Photochemical Behavior of Various Humic Substances in Water: II.
Photosensitized Oxygenations. Chemosphere, 10(1):119-126, 1981.
28. Kitchens, J. F., G. L. Anspach, L. B. Mangoba, and E. A. Hobylynska.
Cleanup of Spilled Chlorinated Organics with the LARC Process. In:
Proceedings of the Hazardous Materials Spills Conference, Philadelphia,
PA, 1984.
29. Prengle, H. W. Jr., C. G. Hewes, and C. E. Mauk. Oxidation of Refractory
Materials by Ozone with Ultraviolet Radiation. In: Proceedings of the
Second International Symposium on Ozone Technology, International Ozone
Institute, Montreal, 1975.
30. Cole, E. R. Jr., A. Y. Lee, and A. L. Paulson. Electrolytic Method for
Recovery of Lead from Scrap Batteries. Report of Investigations 8602,
Report No. R18857, U. S. Department of the Interior, Bureau of Mines,
Rolla, MO, 1984.
31. Rosain, R., and C. Morton. Design and Operation of a 3500-CPM Air
Stripping System for VOC Removal. In: Proceedings of the Int. Water
Conf. Annual Meeting. Eng. Soc. West. EJa. Pittsburgh, PA, 1984.
32. Byers, W. D., and C. M. Morton. Removing VOC from Croundwater-Pilot,
Scale-up, and Operating Experience. Env Progress, 4(2):112-118, 1985.
33. Ellis, W. D., J. R. Payne, and G. D. McNabb. Treatment of Contaminated
Soils with Aqueous Surfactants. Interim Report. EPA Contract No.
68-03-3113, U. S. Environmental Protection Agency, Office of Research and
Development, Cincinnati, OH, 1985.
34. Ellis, W. D., and T. Fogg. Treatment of Soils Contaminated with Heavy
Metals. Interim Report. EPA Contract No. 68-03-3113. Hazardous Waste
Engineering Research Laboratory, Office of Research and Development U. S.
Environmental Protection Agency, Cincinnati, OH.
35. Dow Chemical Co. Keys to Chelation. Dow Chemical Co., Organic Chemical
Dept., Midland, MI, 1985.
36. Black, M. S. Feasibility of Lead Extraction From Battery Waste.
Environmental Health and Safety, EES/Georgia Institute of Technology,
Atlanta, GA, 1984.
37. Silviera, D. J., and L. E. Sommers. Extractability of Copper, Zinc,
Cadmium, and Lead in Soils Incubated with Sewage Sludge. Journal of
Environment Quality, 6 (1): 47-52. Jan-Mar 1977.
48
-------
38. Brown, K. W., J. C. Thomas, and J. F. Slowey. Extractibility of Metals
Applied to Soils in Sewage Effluent. Soil Sci., 138(6):423-431, December
1984.
39. Connick, C. Mitigation of Heavy Metal Migration in Soil. New England
Water Pollution Control Association J., 19(1), 1985.
40. Connick, C., F. Blanc, and J. O'Shaughnessy. Adsorption and Releases of
Heavy Metals in Contaminated Soil. Unpublished study. U. S.
Environmental Protection Agency, Boston, MA, 1985.
41. Farrah, H., and W. F. Pickering. Extraction of Heavy Metal Ions Sorbed
on Clays. Water Air Soil Pollution, 9(4):491-98, 1978.
42. Castle, C. Cost Summary by Task Description and Process Status for the
Immediate Removal at Kenneth Lee Farm, Woodville, WI. Draft Report, U.
S. Environmental Protection Agency, Region V, 1986.
43. U.S. Environmental Protection Agency. EDTA-Pb Soil Extraction Process.
Draft Report. Cincinnati, OH, 1986.
44. Singh, B. R., and R. P. Narwal. Plant Availability of Heavy Metals in a
Sludge-Treated Soil: II. Metal Extractability Compared with Plant Metal
Uptake. J. Env. Quality, 13(3):344-49, 1984.
45. U. S. Environmental Protection Agency. Waste Soil Treatment Study,
Celtor Chemical Works Site, Hoopa, California. Draft Report, EPA
Contract No. 68-01-6692. Hazardous Site Control Division, 1986.
46. Rulkens, W. H., and J. W. Assink. Extraction as a Method for Cleaning
Contaminated Soil: Possibilities, Problems, and Research. In:
Proceedings of the Fifth National Conference on Management of
Uncontrolled Hazardous Waste Sites, Washington, DC, 1984.
47. Zoltek, J. Jr., and J. F. K. Earle. Feasibility Study: Liquid-Liquid
Extraction (LLX) as a Cleanup Process for Groundwater, Soils, and CBW
(chemical and biological warfare) Agents. Final Report,
AFESC/ESL-TR-84-44. Air Force Engineering and Services Center, 1984.
48. Kirk - Othmer. Encyclopedia of Chemical Technology, 3rd Edition,
Vol. 9. John Wiley and Sons, NY, 1979.
49. Johnson, R. E., and R. I. Starr. Ultrarapid Extraction of Insecticides
from Soil Using a New Ultrasonic Technique. J Ag Food Chem, 20(1):48-51,
1972.
50. Hart, L. I. Jr., J. J. Schmidt-Collerus, and L. R. Burroughs. Methods of
Removing Bitumen from Tar Sand Utilizing Ultrasonic Energy and Stirring.
U. S. Patent No. 4,054,506, 1977.
49
-------
51. Hancher, C. V7., M. B. Saunders, and J. M. Googin. Process for Removing
Polychlorinated Biphenyls from Soil. U. S. Patent No. Appl. 6,672,230,
1984.
52. Hancher, C. W., J. M. Napier, and F. E. Kosinski. Removal of PCB from
Oils and Soils. In: Proceedings of the Fifth Department of Energy Env
Protection Conference, Albuquerque, NM, 1984.
53. Saunders, M. B. Pilot Plant Studies for Solvent Extraction of
Polychlorinated Bipheny (PCB) from Soil. 1985 EPRI, PCB Proceedings,
CS/EA/EL-4480.
54. CF Systems Corporation. Organic Extraction System. CF Systems
Corporation, Cambridge, MA, 1987.
55. J. A. Burruel, S. Hitchcock, M. Norman, and M. J. Lampkins. The B.E.S.T.
Sludge Treatment Process: An Innovative Alternative Used at a Superfund
Site.
56. U. S. Army Toxic and Hazardous Waste Materials Agency. Low Temperature
Thermal Stripping of Volatile Organic Compounds from Soil. Report No.
AMXTH-TE-CR 86085, August, 1986.
50
-------
BIBLIOGRAPHY
BIOLOGICAL/HORTICULTURAL
1. Hyde, C. S. The Growing Business of Bacterial Cultures. Biocycle,
22(6):25-29, 1981.
2. Wentsel, R. S., R. H. Foutch, W. E. Harward III, W. E. Jones III, and J.
F. Kitchens. Restoring Hazardous Spill-Damaged Areas: Technique
Identification/Assessment. Project Summary, EPA-600/S2-81-208, U. S.
Environmental Protection Agency, 1981.
3. Lee, C. R., B. L. Folsom Jr., and D. J. Bates. Prediction of Plant Uptake
of Toxic Metals Using a Modified DTPA Soil Extraction. Sci Tot Env,
28:191-202, 1983.
51
-------
DETOXIFICATION. PHOTOCHEMICAL & CHEMICAL CHANGES
1. Christensen, D. C., and W. C. Weiraar. Enhanced Photodegradation of
Persistent Halogenated Organic Materials. Proceedings of the 34th
Industrial Waste Conference, Purdue Univ., Lafayette, IN. Published by
Ann Arbor Sci Publications, Ann Arbor, 1980.
2. Zepp, R. G. , G. L. Baughman, and P. F. Schlotzhauer. Comparison of
Photochemical Behavior of Various Humic Substances in Water: II.
Photosensitized Oxygenations. Chemosphere, 10(1):119-126, 1981.
3. Zepp, R. G., G. L. Baughman, and P. F. Schlotzhauer. Comparison of
Photochemical Behavior of Various Huraic Substances in Water: I. Sunlight
Induced Reactions of Aquatic Pollutants Photosensitized by Humic
Substances. Chemosphere, 10(1):109-117, 1981.
4. Mackay, D., and G. E. Hoag. A Perspective on the Behaviour of Chemicals
Spilled in Soil. Spill Tech Newsletter, II(2):53-71, Ottawa, Canada, 1986.
5. Kitchens, J. A. F. Dehalogenation of Halogenated Compounds. U. S. Patent
No. 4,144,152, 1979.
6. Prengle, H. W. Jr., C. G. Hewes, and C. E. Mauk. Oxidation of Refractory
Materials by Ozone with Ultraviolet Radiation. Second International
Symposium on Ozone Technology, International Ozone Institute, Montreal,
1975.
7. Kitchens, J. F., G. L. Anspach, L. B. Mangoba, and E. A. Hobylynska.
Cleanup of Spilled Chlorinated Organics with the LARC Process. Hazardous
Materials Spills Conference, 1984.
8. Kossow, D. S., and R. C. Ahlert. Design Criteria for In-Situ and On-Site
Renovation of an Industrial Sludge Lagoon. Third International Symposium
on Operating European Hazardous Waste Management Facilities, Odense,
Denmark, 1986.
9. Kossow, D. S., E. A. Dienemann, and R. C. Ahlert. Field Studies of
In-Situ Extraction and Soil Based Microbial Treatment of an Industrial
Sludge Lagoon. Hazardous Wastes and Hazardous Materials HMCRI, Atlanta,
GA, 1986.
52
-------
ELECTROLYSIS -ELECTROCHEMICAL
1. Van Duin, P. J., J. Van Erkel, D. Schraal, and P. J. Van den Driest.
Electrochemical Treatment of Rinsing Water from Extractive Soil
Cleaning. Contaminated Soil International TNO Conference, Nijhoff,
Netherlands, 1986.
53
-------
METAL EXTRACTION
1. Navratil, J. D. Process Chem of 24lAm, J Less Common Metals,
100:189-194, 1984.
2. Farrah, H. , and W. F. Pickering. Extraction of Heavy Metal Ions Sorbed
on Clays. Univ of Newcastle, NSW Australia. Water Air Soil Pollution,
9(4):491-498, 1978.
3. Faber, K. T., and R. L. Landingham. The Separation, Identification and
Characterization of Radioactive Wastes in Topsoil. Powder Tech,
16(2):209-216, 1977.
4. Schulz, R. K., G. A. Tompkins, L. Leventhal, and K. L. Babcock. Uptake
of Plutonium and Americium by Barley from Two Contaminated Test Site
Soils. J Env Quality, 5(4):406-410, 1976.
5. Nishita, H., M. Hamilton, and A. J. Steen. Extractability of 238Pu and
242Cra from a Contaminated Soil as a Function of pH and Certain Soil
Components: HN03--Ha0H System. Soil Sci Soc Am J, 42:31-55, 1978.
6. Nishita, H., and R. M. Haug. The Effect of Fulvic and Humic Acids and
Inorganic Phase of Soil on the Sorption and Extractability of 239Pu
(IV). Soil Sci, 128(5):291-296, 1979.
7. Spalding, B. P. Extraction of Radiostrontium Coprecipitated with Calcium
Carbonate in Soil. Soil Sci Am J, 49(l):69-73, 1985.
8. Cao, H. F., A. C. Chang, and A. L. Page. Heavy Metal Contents of
Sludge-Treated Soils as Determined by Three Extraction Procedures. J Env
Quality, 13(4):632-634, 1984.
9. Silviera, D. J., and L. E. Sommers. Extractability of Copper, Zinc,
Cadmium, and Lead in Soils Incubated with Sewage Sludge. J Env Quality,
6(1):47-52, 1977.
10. MacLean, K. S., and W. M. Langille. Extractable Heavy Metals in Atlantic
Coast Soils. Communications Soil Sci Plant Analysis, 11(11):1041-1049,
1980.
11. Nishita, H., R. M.%Haug, and T. Rutherford. Effect of Inorganic and
Organic Compounds on the Extractability of 239Pu from an Artificially
Contaminated Soil. J Env Quality, 6(4):451-455, 1977.
12. Scott, D., and J. H. Thomas. Comparative Efficiencies of Various Methods
for Extracting Trace Heavy Metals from Soils. Soil Sci, 124(6):319-322,
December 1977.
13. Singh, B. R., and R. P. Narwal. Plant Availability of Heavy Metals in a
Sludge-Treated Soil: II. Metal Extractability Compared with Plant Metal
Uptake. J Env Quality, 13(3):344-349, 1984.
-------
14. Raja, M. E., and B. R. V. Iyengar. Effect of Oven Drying on DTPA
Extractable Zinc. J Indian Soil Sci, 33:433-436, 1985.
15. Brown, K. W., J. C. Thomas, and J. F. Slowey. Extractability of Metals
Applied to Soils in Sewage Effluent. Soil Sci, 138(6):423-431, December
1984.
16. Neuhauser, E. F., and R. Hartenstein. Efficiencies of Extractants Used
in Analyses of Heavy Metals in Sludges. J Env Quality, 9(l):21-22, 1980.
17. Mashhady, A. S. Heavy Metals Extractable from a Calcareous Soil Treated
with Sewage Sludge. Env Pollution/Series B, 8(1):51-62, 1984.
18. Beckett, P. H. T., E. Uarr, and P. Brindley. Changes in the
Extractabilities of Heavy Metals in Water-Logged Sludge-Treated Soils.
J Water Pollution Control Federation. United Kingdom. 82(1):107-113,
1983.
19. Singer, A., and J. Navrot. Extraction of Metals from Basalt by Humic
Acids. Nature, 262:479-481, 1976.
20. Rulkens, W. H., and J. W. Assink. Extraction as a Method for Cleaning
Contaminated Soil: Possibilities, Problems and Research. Fifth National
Conference on Management of Uncontrolled Hazardous Waste Sites,
Washington, DC, 1984.
21. Connick, C., F. Blanc, and J. 0'Shaughnessy. Adsorption and Release of
Heavy Metals in Contaminated Soil. Unpublished Study, U. S.
Environmental Protection Agency, Boston, MA.
22. Ellis, W. D., and T. Fogg. Treatment of Soils Contaminated with Heavy
Metals. Interim Report, Hazardous Waste Engineering Research Laboratory,
Office of Research and Development, U. S. Environmental Protection
Agency, Contract No. 68-03-3113, 1985.
23. Black, M. S. Feasibility of Lead Extraction from Battery Waste. Report
prepared for I. T. Enviroscience, Knoxville, TN.
24. CH2M Hill, Waste Soil Treatment Study, Celtor Chemical Works Site, Hoopa,
California. Draft Report, U. S. Environmental Protection Agency,
Hazardous Site Control Division, 1986.
25. Connick, C. Mitigation of Heavy Metal Migration in Soil. New England
Water Pollution Control Association J, 19(1), 1985.
26. Connick, C. Mitigation of Heavy Metal Migration in Soil. J New England
Water Pollution Control Association, 19(1), 1985.
27. PEI Associates, Inc. EDTA-Lead Soil Extraction Process, Draft Report,
Prepared for U. S. Environmental Protection Agency, 1986.
55
-------
28. Extractable Metals in Soils, Sewage Sludge, Treated Soils and Related
Materials. U. K. Department of the Environment and the National Waste
Council. In Methods for Examining Waters and Associated Materials. 1983.
29. Rietz, E., and H. Soechtig. Extraction Properties and Linkage of Heavy
Metals in Soils with a Different Degree of Contamination,
Landwirtschaftliche Forschung, Sonderheft, 38:382-393, 1982.
30. Elrashidi, M. A., and G. A. O'Connor. Boron Sorption and Desorption in
Soils. Soil Sci Soc Am J, 46(1):27-31, 1982.
31. Blom, B. E. Sorption of Cadmium by Soils. Research Report
No. CRREL-RR-320. National Science Foundation. Cold Regions Research and
Engineering Laboratory, U.S. Army Corps of Engineers, Contract
No. DA-4-A-162121-A-891, 1974.
32. Bruns, L. E. Conceptual System for Removal of Plutonium from Soils and
Scrap. Actinide Recovery Symposium, International, N.Y.: Harwood
Academic Publishers, 1982.
33. Dow Chemical Co. Keys to Chelation. Organic Chemicals Dept., Midland,
MI, 1985.
34. Kochen, R. L., W. W. Schulz, and J. D. Navratil. Americium and Plutonium
Removal from Contaminated Soil. Actinide Recovery Symposium,
International, N.Y.: Harwood Academic Publishers, 1982.
35. IT Corporation. Quick Response Feasibility Testing of Lead Removal from
Contaminated Fill Materials by Extraction with EDTA for Application to
the EERU Mobile Drum Washer Unit. Draft Report, Project No. 9656.01,
U. S. Environmental Protection Agency, Oil and Hazardous Materials
Simulated Environmental Test Tank (OHMSETT), 1984.
36. Haddock, J. D., P. F. Landrum, and J. P. Giesy. Extraction Efficiency of
Anthracene from Sediments. Analytical Chem, 55(7):1197-1200, 1983.
37. Gibson, M. J., and J. G. Farmer. Multi-Step Sequential Chemical
Extraction of Heavy Metals from Urban Soils. Environ Pollution/Series B,
11(2):117-136, 1986.
38. Elias, H. H. Comparison of Alternate Technologies for the Removal of Lead
from Contaminated Solids. IT Draft Report for U. S. Environmental
Protection Agency, Office of Research and Development, EPA Contract
No. 68-03-3069, Cincinnati, 1984.
39. Ritcey, G. M., and M. Silver. Lysimeter Investigations on Uranium
Tailings at CANMET. Canadian Mining Metallurgical Bulletin, 75(846):
134-143, 1982.
40. Eagle Iron Works. Eagle Fine Material Phosphate Washer Dewaterer.
General Catalog Section C-l, 1981.
56
-------
41. Jeffers, T. H., and R. D. Groves. Using Solvent - Impregnated Carbon to
Recover Copper from Oxidized Mill Tailings. U. S. Department of the
Interior, Bureau of Mines. Report of Investigations 8966, Salt Lake City
Research Center, Salt Lake City, 1985.
42. Castle, C. Cost Summary by Task Description and Process Status for the
Immediate Removal at Kenneth Lee Farm, Woodville, WI. Unpublished
Internal Report, U.S. Environmental Protection Agency, Region V, 1986.
43. Grove, J. H., and B. G. Ellis. Extractable Iron and Manganese as Related
to Soil pH and Applied Chromium. Soil Sci Soc Am J, 44:243-246, 1980.
44. Kirk-0thiner , Encyclopedia of Chemical Technology, Third Edition, Vol. 9,
John Wiley and Sons, New York, 1979.
45. PEI Associates, Inc. Lessons Learned at Hazardous Waste Sites, Physical
Treatment Processes. Draft Report. EPA Contract 68-03-3413. U.S.
Environmental Protection Agency, Office of Research and Development,
Cincinnati, Ohio, 1988.
46. PEI Associates, Inc. Electromembrane Process for Recovery of Lead from
Contaminated Soils. Phase I, Final Report, National Science Foundation.
Washington, DC, 1986.
47. Phillip, T.A. Economic Evaluation of an Electrolytic Process to Recover
Lead from Scrap Batteries. U.S. Bureau of Mines, Information Circular
9071.
48. Phillip, T.A. Initial Assessment of the Economic Potential of a
Hypothetical Process to Treat Battery Breaker Residue Using
Leach-Electrowinning Technology. Internal Report, U.S. Bureau of Mines,
1987.
49. Phillip, T.A. Conceptual Process Design and Cost Estimate for Removing
Lead from Soil at the United Scrap Lead Superfund Site. Internal Report,
U.S. Bureau of Mines, 1988.
50. CDM Federal Programs Corporation. Performance of Remedial Response
Activities at Uncontrolled Hazardous Waste Sites. Draft Report, EPA
Contract 68-01-6939. U.S. Environmental Protection Agency, Washington,
DC, 1988.
51. Nash, J.M. Laboratory Study of Aqueous Washing of Soil from Polycarb
Site, Wells, Nevada. Draft Report, EPA Contract 68-03-3203. U.S.
Environmental Protection Agency, Office of Research and Development,
Cincinnati, Ohio, 1987.
52. Evangelista, R. Soil Treatability Studies for Polycarb Site, Wells,
Nevada. Draft Report, U.S. Environmental Protection Agency, Hazardous
Response Support Division, Edison, NJ, 1987.
57
-------
ORGANICS EXTRACTION
1. Rulkers, W. H., J. W. Assink, and W. J. Van Geinert. Development of an
Installation for On-Site Treatment of Soil Contaminated with Organic
Bromine Compounds. Netherlands Organization for Applied Research,
Division of Technology for Soc, Apeldoorn, The Netherlands, International.
2. Scholz, R., and J. Milanowski. Mobile System for Extracting Spilled
Hazardous Materials from Soils. Report, Contract Number 68-03-2696, U.S.
Environ Protection Agency, Office of Research and Development,
Cincinnati, OH. 1982.
3. Ellis, W. D., and D. L. Michaelsen. Information Search Report for the
Chemical Countermeasures Program. U. S. Environmental Protection
Agency, EPA Contract 68-01-3113. Oils and Hazardous Material Spills
Branch, Edison, N.J. 1982.
4. Ellis, W. D., J. R. Payne, and G. D. McNabb. Treatment of Contaminated
Soils with Aqueous Surfactants (Interim Report). EPA Contract
No. 68-03-3113, U.S. Environmental Protection Agency, Office of Research
and Development, Cincinnati, OH. 1985.
5. Nathwani, J. S., and C. R. Phillips. Adsorption-Desorption of Selected
Hydrocarbons in Crude Oil on Soils. Chemosphere, 6(4):157-162, 1977.
6. Wheeler, W. B., N. P. Thompson, R. L. Edelstein, and R. T. Krause.
Ultrasonic Extraction of Carbofuran Residues from Radishes. Bulletin
Environ Contamination Toxicology, 21(1):238-242, 1979.
7. Fowlie, P. J. A., and T. L. Bulman. Extraction of Anthracene and
Benzo(A)pyrene from Soil. Analytical Chem, 58(4):721-723, 1986.
8. Meadus, F. W. , and B. D. Sparks. Effect of Agglomerate Pore Structure on
Efficiency of Solid-Liquid Separation by an Agglomeration Technique: Use
of a Model System. Sep Sci Tech, 18(4):341-362, 1983.
9. Blaine, N. F., and G. Blaine. Solvent Extraction of Oil from Tar Sands
Utilizing a Trichloroethylene Solvent. U. S. Patent No. 4,046,669, 1977.
10. Wolff, W. F. Method for Extraction Solvent Recovery. U. S. Patent
No. 4,548,701, 1985.
11. Mouchet, P. F. Berne, and A. Puill. Coalescense on Sand: Principle of
Process and Its Application to the Recovery of Solvents in
Hydrometallurgy. Industrie Minerale, les Techniques. Table Ronde 1983
de la Section Mine, Paris. 487-496, 1983.
12. Klins, M. A., S. M. Farouqali, and C. D. Stahl. Tertiary Recovery of the
Bradford Crude by Micellar Slugs and Three Different Polymer Buffers.
ERDA (Emergency Research and Development Administration) DOE Contract
No. E(40-l)-5078, 1976.
58
-------
13. Texas Research Institute Inc. Test Results of Surfactant Enhanced
Gasoline Recovery in a Large-Scale Model Aquifer. American Petroleum
Institute Publication 4390, 1982.
14. Kelterborn, J. C., and R. A. Stone, Method for Filtering Solvent and Tar
Sand Mixtures. U. S. Patent No. 4,539,097, 1985.
15. Yildirim, E. In-Site Bitumen Recovery by Percolation. Canada Patent No.
1,195,920, 30, 1985.
16. Zoltek, J. Jr., and J. F. K. Earle. Feasibility Study: Liquid-Liquid
Extraction (LLX) as a Cleanup Process for Groundwater, Soils, and CBW
(chemical and biological warfare) Agents. Final Report,
AFESC/ESL-TR-84-44. Air Force Engineering and Services Center, 1984.
17. Benson, A. M. Filtration of Solvent-Water Extracted Tar Sand. U. S.
Patent No. 3,459,653, 1966.
18. Coulson, G. R. Hot Water Process for the Extraction of Oil from
Bituminous Sands. U. S. Patent No. 2,968,603, 1961.
19. Hart, L. I. Jr., J. J. Schmidt-Collerus, and L. R. Burroughs. Method of
Removing Bitumen from Tar Sand Utilizing Ultrasonic Energy and Stirring.
U. S. Patent No. 4,054,506, 1977.
20. Mathews, A. P., and L. T. Fan. Comparison of Performance of Packed and
Seraifluidized Beds for Adsorption of Trace Organics, Adsorption and Ion
Exchange - 83 AICHE Symposium Series, 79(230):79-85, 1983.
21. Sutikno, T., and K. J. Himmelstein. Desorption of Phenol from Activated
Carbon by Solvent Regeneration. Industrial Eng Chem Fund, 22:420-425,
1983.
22. Johnson, R. E., and R. I. Starr. Ultrasonic Extraction of Insecticides
in Soil II Refinement of the Technique. J Econ Entomology,
63(1):165-168, 1970.
23. Johnson, R. E., and R. I. Starr. Ultrarapid Extraction of Insecticides
from Soil Using a New Ultrasonic Technique. J Ag Food Chem, 20(1):48-51,
1972.
59
-------
POLYCHLORINATED BIPHENYLS CPCB')
1. Hancher, C. W. , J. M. Napier, and F. E. Kosinski. Removal of PCB from
Oils and Soils. Fifth Department of Energy Env Protection Conference,
Albuquerque, NM, 1984.
2. Hancher, C. W. , M. B. Saunders, and J. M. Googin. Process for Removing
Polychlorinated Biphenyls from Soil. U. S. Patent No. Appl. 6,672,230,
1984.
3. Kitchens, J. F., W. E. Jones III, G. L. Anspach, and D. C. Schubert.
Light-Activated Reduction of Chemicals for Destruction of Polychlorinated
Biphenyls in Oil and Soil. In Detoxification of Hazardous Waste, edited
by J. H. Exner. Ann Arbor Science Publications, Ann Arbor, 1982.
60
-------
SUPERCRITICAL FLUIDS
1. Eggers, R. Large-Scale Industrial Plant for Extraction with
Supercritical Gases. In Extraction with Supercritical Gases, edited by
G. M. Schneider, G. Wilke, and E. Stahl. Zcchnersche Buchdrukerei, West
Germany, 1980.
2. Eggers, R., and R. Tschiersch. Development and Design of Plants for
High-Pressure Extraction of Natural Products. In Extraction with
Supercritical Gases, edited by G. M. Schneider, G. Wilke, and E. Stahl.
Zechnersche Buchdruckerci, West Germany, 1980.
3. Ehntholt, D. J., C. P. Eppig, and K. E. Thron. Isolation and
Concentration of Organic Substances from Water: An Evaluation of
Supercritical Fluid Extraction. Project Summary, EPA-600/S1-84-028,
U. S. Environmental Protection Agency, Health Effects Research
Laboratory, Research Triangle Park, NC, 4, 1985.
4. Schneider, G. M. Physicochemical Principles of Extraction with
Supercritical Gases. In Extraction with Supercritical Gases, edited by
G. M. Schneider, E. Stahl, and G. Wilke. Verlag-Chemie, West Germany,
1980.
5. Tsekhanskaya, Yu. V., M. B. Iomotev and E. V. Muskina. Solubility of
Diphenylaraine and Naphthalene in Carbon Dioxide Under Pressure. Russian
J Phys Chem, 1177-1181, 1962.
6. Spiteller, M. Extraction of Soil Organic Matter by Supercritical Fluids.
Proceedings of the First Meeting of Hie International Humic Substances
Soc, Estes Park, CO, 8(1) : 111-113 , 1983.
7. Fetzer, J. C., J. C. Graham, R. F. Arrendale, M. S. Klee, and L. B.
Rogers. Characterization of Carbonaceous Materials Using Extraction with
Supercritical Pentane. Separation Sci Tech, 16(1):975-111, 1981.
8. Modell, M., R. P. de Filippi, and V. Krukonis. Regeneration of Activated
Carbon with Supercritical Carbon Dioxide. Activated Carbon Adsorption
Organization Aqueous Phase, 1:447-461, 1980.
9. Modell, M., G. G. Gaudet, M. Simson, G. T. Hong, and K. Biernann.
Destruction of Hazardous Waste using Supercritical Water. Eighth Annual
Research Symposium on Land Disposal, Incineration, and Treatment of
Hazardous Waste, Ft. Mitchell, KY, 1982.
10. Groves, F. R. Jr., B. Brady, and F. C. Knapf. State-of-the-Art on the
Supercritical Extraction of Organics from Hazardous Wastes. CRC Critical
Reviews in Environ Control, 15(3):237-274, 1985.
11. Modell, M., R. C Reid, and S. I. Amin. Gasification Process. U. S.
Patent No. 4,113,446, 1978.
61
-------
12. Modell, M. Processing Methods for the Oxidation of Organics in
Supercritical Water. U. S. Patent No. 4,338,199, 1982.
13. Morozov, V. S., and E. G. Vinkler. Measurement of Diffusion Coefficients
of Vapors of Solids in Compressed Gases I Dynamic Method for Measurement
of Diffusion Coefficients. Russian J Phys Chem, 49(9):1404-1405,1975.
14. McHugh, M. A., M. W. Mallett, and J. P. Kohn. High Pressure Fluid Phase-
Equilibria of Alcohol-Water-Supercritical Solvent Mixtures. In Chemical
Engineering at Supercritical Fluid Conditions, edited by M. E. Paulaitis,
J. M. L. Penninger, R. D. Gray, Jr. and P. Davidson. Ann Arbor: Ann
Arbor Science Publications, 1983.
15. Huk, M. S., and J. C. Montagna. Solubility of Oxygenated Hydrocarbons in
Supercritical Carbon Dioxide. In Chemical Engineering at Supercritical
Fluid Conditions, edited by M. E. Paulaitis, J. M. L. Penninger, R. D.
Gray, Jr., and P. Davidson. Ann Arbor: Ann Arbor Science Publications,
1983.
16. King, M. B., D. A. Alderson, D. L. Fallah, F. H. Kassin, K. M. Kassira, J.
R. Sheldon, and R. S. Mahmud. Some Vapor/Liquid and Vapor/Solid
Equilibrium Measurements of Relevance for Supercritical Extraction
Operations, and their Correlation. In Chemical Engineering at
Supercritical Fluid Conditions, edited by M. E. Paulaitis, J. M. L.
Penninger, R. D. Gray, Jr., and P. Davidson. Ann Arbor: Ann Arbor
Science Publications, 1983.
17. Streett, W. B. Phase Equilibria in Fluid and Solid Mixtures at High
Pressure. In Chemical Engineering at Supercritical Fluid Conditions,
edited by M. E. Paulaitis, J. M. L. Penninger, R. D. Cray, Jr., and P.
Davidson. Ann Arbor: Ann Arbor Science Publications, 1982.
18. Tsekhanskaya, Y. B., M. B. Iomtev, and E. V. Mushkina. Solubility of
Naphthalene in Ethylene and Carbon Dioxide Under Pressure. Russian J
Phys Chem, 38(9):1173-1176, 1964.
19. Ziger, D. H., and C. A. Eckert. Correlation and Prediction of
Solid-Supercritical Fluid Phase Behavior. Industrial Kng Chem Process
Design and Development, 22(4):582-588, 1983.
20. Francis, A. W. Ternary Systems of Liquid Carbon Dioxide. J Phys Chem,
58:1099-1114, 1954.
21. Mackay, M. E., and M. E. Paulaitis. Solid Solubilities of Heavy
Hydrocarbons in Supercritical Solvents. Industrial Eng Chem Fund,
18(2):149-153, 1979.
22. Johnston, K. P., D. H. Ziger, and C. A. Eckert. Solubilities of
Hydrocarbon Solids in Supercritical Fluids-Hie Augmented van del" Waals
Treatment. Industrial Eng Chem Fund, 21(3):191-197, 1982.
62
-------
23. Diepen, G. A. M., and F. E. C. Scheffer. The Solubility of Naphthalene
in Supercritical Ethylene. II. J Phys Chem, 57:575-577, 1953,
24. Van Leer, R. A., and M. E. Paulaitis. Solubilities of Phenol and
Chlorinated Phenols in Supercritical Carbon Dioxide. J Chem Eng Data,
25:257-259, 1980.
25. Prausnitz, J. m., and P.R. Benson. Solubility of Liquids in Compressed
Hydrogen, Nitrogen, and Carbon Dioxide. Am Institute Chem Eng Data,
26(1):47-51, 1981.
26. Kurnik, R. T., S. J. Holla, and R. C. Reid. Solubility of Solids in
Supercritical Carbon Dioxide and Ethylene. J Chem Eng Data, 26(1):47-51,
1981.
27. McHugh, M., and M. E. Paulaitis. Solid Solubilities of Naphthalene and
Biphenyl in Supercritical Carbon Dioxide. J Chem Eng Data,
25(4):326-329, 1980.
28. deFilippi, R. P., and R. J. Robey. Supercritical Fluid Regeneration of
Adsorbents. Project Summary, EPA-600/52-83-038, U. S. Environmental
Protection Agency, Industrial Environmental Research Laboratory, Research
Triangle Park, NC, 1983.
29. King, M. B., and T. R. Bott. Problems Associated with the Development of
Gas Extraction and Similar Processes. Separation Sci Tech,
17(1):119-150, 1982.
30. Eisenbach, W., and K. Niemann. Distillation-Extraction with
Supercritical Gases - A Way to Obtain Valuable Substances from Tar Sands,
Brown Coal Tar, and Petroleum Residues. Erdoel & Kohle, Erdgas,
Petrochemie, Federal Republic of Germany. 34(7):296-300, 1981.
31. Spiteller, M. A New Procedure for the Extraction of Organic Matter from
Soils by Supercritical Gases. Bayreuth, Federal Republic of Germany:
Z. Pflanzenernaehr, Bodenkd, 145(5):483-492, 1982.
32. Bott, T. R. Supercritical Gas Extraction - Some Observations. Third
Process National Meeting, South African Institute of Chemical Engineers,
1980.
33. Zosel, K. Separation with Supercritical Gases: Practical Applications.
Angewandte: Chemical/International Edition, 17:702-709, 1978.
34. Schneider, G. M. Physicochemical Principles of Extraction with
Supercritical Gases. Angewandte Chemical/International Edition,
17:716-727, 1978.
35. Capriel, P., A. Haisch, and S. U. Khan. Supercritical Methanol: An
Efficacious Technique for the Extraction of Bound Pesticide Residues from
Soil and Plant Samples. J Ag Food Chem, 34(l):70-73, 1986.
63
-------
36. Brady, B. 0., Jr. Supercritical Extraction of Soils Contaminated with
Hazardous Organics. Thesis, the Department of Chemical Engineering,
Louisiana State University, Baton Rouge, LA, 1986.
37. Randhava, R., and S. Calederone. Hazard Analysis of Supercritical
Extraction. Chem Eng Progress, 59-62, June 1985.
64
-------
VOLATILE ORGANIC COMPOUNDS (VOC)
1. Stallings, R. L., T. N. Rogers, and R. L. Gross. Air Stripping of
Groundwater Organics. Proceedings of the American Defense Preparedness
Association, 14th Environmental Systems Symposium, 1985.
2. Byers, W. D., and C. M. Morton. Removing VOC from Groundwater-Pilot,
Scale-up, and Operating Experience. Env Progress, 4(2):112-118, 1985.
3. Van Aswegen, P. C.p The Clarification of Uranium Pregnant Solution at
Buffelsfontein by a Circulator Clarifier. J South African Inst Mining
Metallurgy, 83(4):87-91, 1983.
4. Anastos, G. J., M. H. Corbin, M. F. Coia, and P. J. Marks. Task 11:
In Situ Air Stripping of Soils. Pilot Study, Final Report, U. S. Army
Toxic and Hazardous Materials Agency, Contract No. DAAK11-82-C-0017, 1985.
5. Raczko, R. F., J. E. Dykeson, and M. B. Denove. Pilot-Scale Studies of
Air Stripping for Removal of Volatile Organics from Ground Water.
Industrial Waste Processing Mid-Atlantic Conference, 1982.
6. Baldauf, G. Removal of Volatile Halogenated Hydrocarbons by Stripping
and/or Activated Carbon Adsorption. Water Supply, Berlin 'B,'
3(1):187-196, 1985.
7. Rasquin, E. A., S. Lynn, and D. N. Hanson. Vacuum Stream Stripping of
Volatile, Sparingly Soluble Organic Compounds from Water Streams.
Industrial Eng Chem Fund, 17(3):170-174, 1978.
8. R. F. Weston, Inc., Low Temperature Thermal Stripping of Volatile Organic
Compounds from Soil. Report, U. S. Army Toxic and Hazardous Waste
Materials Agency, November 1985.
65
-------
SURVEY STUDIES
1. Camp Dresser & McKee, Inc. Alternative Technologies for Treatment and
Disposal of Soils Contaminated with Organic Solvents. Versar EPA
Contract No. 68-01-7053, U. S. Environmental Protection Agency, 1985.
2. Rulkers, W. H., J. W. Assink, and W. J. Van Gemert. On Site Processing
of Contaminated Soil, Contaminated Land Reclamation and Treatment, edited
by M. A. Smith. Plenum Press, New York, 1985.
3. Van Luin, A. B., and H. Warner, Treatment of Polluted Water from the
Clean-Up of Contaminated Soil. Rijkswaterstaat, Institute for Inland
Water Management and Wastewater Treatment, Telyrtad, Netherlands.
4. Davies, B. E. Halkyn Mountain Project Report: A Summary of Research
Work, 1976-1983. Report to the Welsh Office, 84, 1983.
5. Law Engineering Testing Company. Literature Inventory: Treatment
Techniques Applicable to Gasoline Contaminated Ground Water. Report to
American Petroleum Institute, Washington, DC, 1982.
6. DePoorter, G. L., and T. E. llakonson. Novel Experiments for
Understanding the Shallow Land Burial of Low-Level Radioactive Wastes.
International Symposium on the Scientific Basis for Nuclear Waste
Management, Boston, MA. Materials Research Society, 1981.
7. Leenheer, J. A. Fractionation Techniques for Aquatic Humic Substances.
In Humic Substances in Soil, Sediment, and Water; Geochemistry; Isolation
and Characterization, edited by G. R. Aiken, D. M. McKnight, R. L.
Wershaw. John Wiley, NY, 1985.
8. Freeman, H. M., and E. T. Oppelt. Innovative Thermal Processes for
Hazardous Waste Treatment and Destruction. EPA/600/D-85/169, Thermal
Destruction Branch, Alternative Technologies Division, Hazardous Waste
Engineering Research Laboratory, Office of Research and Development,
U. S. Environmental Protection Agency, Cincinnati, OH, 1985.
9. Frank, S. J., R. F. S. Freitas, W. J. Maism, and E. L. Cussler.
Concentration of Hazardous Wastes with Near Critical Gels. Third
International Symposium on Operating European Hazardous Waste Management
Facilities, Odense, Denmark, 1986.
10. Overcash, M. R. Waste Reduction Technology as a Hazardous Waste
Management Alternative. Third International Symposium on Operating
European Hazardous Waste Management Facilities, Odense, Denmark, 1986.
66
-------
Appendix, Priority Pollutants and Acutely Hazardous Substances
Material
Hydro-
ph i I i c
Hydro-
phobic
VoI at i t e
Met
Votati les
acrolein
acrylonitrile
benzene
bromoform
carbon tetrachloride
chlorobenzene
chlorodibromomethane
chloroform
dich torobromomethane
111-dichI oroethane
1,2-dichloroethane
1.1-dichloroethylene
1.2-di chloropropane
1.3-di chloropropylene
ethylbenzene
methyl bromide
methyl chloride
methylene chloride
tetrachI or©ethylene
toluene
1t2'dichloroethylene
1,1,1 -1r ichloroethane
1,1,2-1 richIgroethane
triehtoroethylene
vinyl chloride
yes
yes
no
no
no
no
no
no
no
no
no
no
no
no
no
no
yes
yes
no
no
no
no
no
no
no
no
no
yes
yes
yes
yes
yes
no
no
no
no
no
yes
no
yes
no
no
no
yes
yes
no
yes
yes
yes
no
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
Acid Extractables
2-chlorophenol
2,4-dfchlorophenol
2,4'dimethylphenot
4,6'dimtrocresol
2,4'dfnf trophenol
p*chloro m-cresol
2-nitrophenol
pentachIorophenoI
phenol
2,4,6-tr ichIorophenoI
yes
no
yes
no
no
no
no
no
yes
no
yes
yes
yes
yes
yes
yes
no
yes
no
yes
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
Base - Neutral Extractables
acenaphthene
acenaphthylene
no
no
yes
yes
no
no
no
no
(cont inued)
67
-------
Appendix (continued)
Hydro- Hydro-
Material philic phobic Volatile Metal
anthracene
no
yes
no
no
benzidine
no
no
no
no
benzo(a)anthracene
no
yes
no
no
benzo(a)pyrene
no
yes
no
no
3,4* benzofluoranthene
no
yes
no
no
benzo(ghi)perylene
no
yes
no
no
benzo(k)fluoranthene
no
yes
no
no
di ch loroethoxyitethane
yes
no
no
no
bis(2-chloroethyl)ether
yes
no
no
no
dichloroisopropyl ether
no
yes
no
no
diethylhexyl phthalate
no
yes
no
no
4•broraophenyl phenyl ether
no
yes
no
no
butylbenzyl phthalate
no
yes
no
no
2* chIoronaphthalene
no
yes
no
no
4•chIorophenyl phenyl ether
no
yes
no
no
chrysene
no
yes
no
no
dibenzo(a,h)anthracene
no
yes
no
no
1,2 dlchlorobenzene
no
yes
yes
no
1,3 dichlorobenzene
no
yes
no
no
1,4 dichlorobenzene
no
yes
no
no
3,31di chlorobenz i dene
no
yes
no
no
diethyl phthalate
no
yes
no
no
dimethyl phthalate
no
yes
no
no
di*n-butyl phthalate
no
yes
no
no
2,4-di ni trotoluene
no
yes
yes
no
2,6-dini trotoluene
no
yes
yes
no
di-n-octyl phthalate
no
yes
no
no
1,2-diphenylhydrazine
no
yes
no
no
fluoranthene
no
yes
no
no
fluorene
no
yes
no
no
hexachlorobenzene
no
yes
no
no
hexachlorobutadiene
no
yes
no
no
hexachlorocyclopentadiene
no
yes
no
no
hexachlorethane
no
yes
no
no
indenoO ,2,3-cd)pyrene
no
yes
no
no
i sophorone
yes
no
no
no
naphthalene
no
yes
no
no
nitrobenzene
no
no
no
no
N-ni trosodimethylamine
yes
no
yes
no
H-nitrosodiphenylamine
no
yes
no
no
N-ni trosodipropylamine
no
no
no
no
phenanthrene
no
yes
no
no
pyrene
no
yes
no
no
1,2,4-trichlorobenzene
no
yes
no
no
(cont i nued)
6S
-------
Append i x (cont i nued)
Material
Hydro-
ph ilfc
Hydro-
phobic
Vol at ile
Metal
Pesticides
aldrin
alpha BHC
beta BHC
gamma BHC
delta BHC
chlordane
4,4'-DDT
4,4'-DDE
4,4*-DDD
dieldrin
alpha endosulfan
beta endosulfan
endosulfan sulfate
endrin
endrin aldehyde
heptachlor
heptachlor epoxide
PCBs
toxaphene
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
Metals
antimony
arsenic
beryl Ii um
cadmium
chromium
copper
lead
mercury
ni ckel
selenium
si Iver
tha11ium
zinc
cyanide
asbestos
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
yes
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
no
yes
yes
no
yes
yes
yes
yes
yes
yes
no
yes
yes
yes
no
no
Acutely Hazardous Mater i a Is
acetaldehyde
allyl alcohol
allyl chloride
amyl acetate
aniIi ne
benzoni tri le
yes
yes
no
yes
yes
no
no
no
yes
yes
yes
yes
yes
yes
yes
yes
no
no
no
no
no
no
no
no
(continued)
69
-------
Appendix (cont inued)
Hydro-
Hydro*
Material
ph i I i c
phobic
Vol at iIe
Met;
benzyl chloride
no
yes
yes
no
butyl acetate
yes
yes
yes
no
butyl amine
yes
no
yes
no
captan
no
no
no
no
carbaryl
no
yes
no
no
carbofuran
no
yes
no
no
carbon disulfide
no
no
yes
no
ch lorpyri fos
no
yes
no
no
coumaphos
no
yes
no
no
cresol
no
yes
no
no
crotonaldehyde
yes
no
yes
no
cyclohexane
no
yes
yes
no
2,4-D
no
yes
no
no
di az i non
no
yes
no
no
dicamba
dichlobeniI
no
yes
no
no
dichlone
no
yes
no
no
2,2'dichloropropionic
yes
no
no
no
dichlorvos
yes
yes
no
no
diethyl amine
yes
no
yes
no
dimethyl amine
yes
no
yes
no
dinitrobenzene
no
no
no
no
diquat
yes
no
no
no
disulfoton
no
no
no
no
di uron
no
yes
no
no
epichlorohydrin
yes
yes
yes
no
ethion
yes
yes
no
no
ethylene diamine
yes
no
yes
no
ethylene dibromide
no
yes
yes
no
formaldehyde
yes
no
yes
no
furfural
yes
no
no
no
guth i on
no
yes
no
no
isoprene
no
yes
yes
no
isopropanolamine DBS
yes
yes
no
no
kelthane
kepone
yes
yes
no
no
ma lath ion
no
yes
no
no
mercaptodimethur
methoxychlor
no
yes
no
no
methyl mercaptan
no
yes
yes
no
methyl methacrylate
no
yes
yes
no
methyl parathion
no
yes
no
no
mevinphos
yes
yes
yes
no
mexacarbate
no
yes
no
no
monoethyl amine
yes
no
yes
no
monomethyl amine
yes
no
yes
no
(continued)
70
-------
Append i x (cont i nued)
Mater i a I
Hydro*
ph i I i c
Hydro-
phobi c
Volatile
Metal
naled
naphthenic acid
ni trotoluene
no
yes
no
no
parathion
no
yes
no
no
phenolsulfate
phosgene
no
no
yes
no
propargi te
yes
no
yes
no
propylene oxide
yes
no
yes
no
pyrethrins
no
yes
no
no
qui noIine
yes
yes
no
no
resorcinol
yes
no
no
no
strontium
yes
no
no
yes
strychnine
no
yes
no
no
styrene
no
yes
no
no
2,4,5-T
no
yes
no
no
TDE
2,4,5-TP
trichlorofon
triethonolamine DBS
triethyl amine
yes
no
yes
no
trimethyl amine
no
yes
yes
no
uranium
yes
no
no
yes
vanadi um
yes
no
no
yes
vinyl acetate
yes
yes
yes
no
xyIcno
no
yes
yes
no
xylenol
yes
yes
no
no
zi rconium
yes
no
no
yes
*Source: CFR AO Parts 122.21
7/
-------
TECHNICAL REPORT DATA
Jattnutuxu m Mr «ww tefw*
1. HtfQrtT MO.
7.
la. » fcCiritKT~S ACCtSSION MO,
EPA/GD0/2-UV/024
4. TITt»& ANO SUBTITLE
ft, BfcPQUT DATS
June 1909
Cleaning Excavated Soil Using Extraction Agents
A State-of-tiie-Art Review
4. PIMOAMINO ORGANIZATION COBI
7. AUTHOR1S1
R, Raghavan, D. Dietz, and E. Coles
tLF£ft?OAMIMC OACAMI2ATION ItfcPOitT NO*
------- |