TREATMENT OF CONTAMINATED SOILS
WITH AQUEOUS SURFACTANTS
PB86-122561
-------
PES6-12256-.
Treatment of Contaminated Soils with
Aqueous Surfactants
Science Applications International Corp.
McLean, VA
Prepared for
Environmental Protection Agency
Cincinnati, OH
Nov 85
U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
-------
EPA/600/2-85/129
November 1985
TREATMENT OF CONTAMINATED SOILS WITH AQUEOUS SURFACTANTS
by
William D. EJJis
James R. Payne
G. Daniel McNabb
Science Applications International Corporation
8400 Westpark Drive
McLean, VA 22102
Contract No. 68-03-3113
.Project Officer
Anthony N. Tafuri
Hazardous Waste Engineering Research Laboratory
Releases Control Branch
Edison, NJ 08837
HAZARDOUS WASTE ENGINEERING RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA/600/2-85/129
2.
RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
TREATMENT OF CONTAMINATED SOILS WITH
AQUEOUS SURFACTANTS
REPORT DATE
November 1985
PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
W.D. Ellis, J.R. Payne and G.D. McMabb
. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Science Applications International Corporation
8400 Westpark Drive
McLean, VA 22102
0. PROGRAM ELEMENT NO.
TEJY1A
1. CONTRACT/GRANT NO.
68-03-3113
12. SPONSORING AGENCY NAME AND ADDRESS
Hazardous Waste Enginearing Research Laboratory
Office of Research and Development
U.S. Environmental Protection Ajency
Cincinnati, Ohio 45268
3. TYPE OF REPORT AND PERIOD COVERED
nterim Report May'82-Auq '85
4. SPONSORING AGENCY CODE
EPA/600/11.
15. SUPPLEMENTARY NOTES
Project Officer: Anthony
Tafuri (?01) 321-^504
16. ABSTRACT
The overall objective of this project was to develop a technical base for decisions on the use of chemical
counter-measures at releases of hazardous substanc-s. Work included a literature search to determine the nature
and quantities of contaminants at Superfund sites and the applicability of existing technology to n situ treatment
Of contaminated solK. I ahnratnrv etiiHio.; uprp rnnrtiirtari t« Ha-.nl,,,, ,_ • j • •» •— — <•'eauneni
•» were tanaucieu to aeveiop an improved in situ t
inificant enhancement to the efficiency of water
water used in a continuous recycle.
The use of aqueous nonionic surfactants for cleaning soil spiked with PCBs. petroleum hydrocarbons and
chlorophenol was developed through shaker table and soil column iests. ContaminantVe^'aT from the soil was 92'
for the PCBs, using 0.751 each of Adsee 799* (Witco Chemical) and Hyonic NP-90» (Diamond Shamrock) in water For
the Petroleum hydrocarbons, the removal with a Z% aqueous solution of each surfactant was 931 These removals
are orders of maomtude Greater than nhminori wit* <..«<• u,»«. i.^__ .-^ .:__ •"•"«""• ""» »-»»• mese removals
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
6.IDENTIFIERS/OPEN ENDED TERMS
COSATi l-'icld/Gruup
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS /This Report/
UNCLASSIFIED
21. NO. OF PAGES
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (R«». 4-77) PREVIOUS COITION is OBSOLETE
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NOTICE
This document has been reviewed in accordance with U.S. Environmental
Protection Agency policy and approved for publication. Mention of trade names
or commercial products does not constitute endorsement or recommendation for
use.
11
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FOREWORD
Today's rapidly developing and changing technologies and industrial
products and practices frequently carry with them the increased generation of
solid and hazardous wastes. These materials, if improperly dealt with, can
threaten both public health and the environment. Abandoned waste sites and
accidental releases of toxic and hazardous substances to the environment also
have important environmental and public health implications. 'The Hazardous
Waste Engineering Research Laboratory assists in providing an authoritative
and defensible engineering basis for assessing and solving these problems.
Its products support the policies, programs, and regulations of the
Environmental Protection Agency, the permitting and other responsibilities of
State and local governments and the needs of both large and small businesses
in handling their wastes responsibly and economically.
This report describes the development of a countermeasure for in situ
cleanup of organic soil contaminants using aqueous surfactants, and will be
useful to those who develop and test in situ chemical counter-measures. For
further information, please contact the Land Pollution Control Division of the
Hazardous Waste Engineering Research Laboratory.
David G. Stephan, Director
Hazardous Waste Engineering
Research Laboratory
m
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ABSTRACT
This report presents the results, conclusions, and recommendations of a
project performed to develop a technical base for decisions on the use of
chemical countermeasures at releases of hazardous substances. The project
included a brief literature search to determine the nature and quantities of
contaminants at Superfund sites and the applicability of existing technology
to in situ treatment of contaminated soils. Laboratory studies were conduc-
t'ecTTo develop an improved methodology applicable to the in situ treatment of
organic chemical contaminated soil.
Current technology for removing contaminants from large volumes of soils
(too large to excavate economically) has been limited to in situ "water wash-
ing." Accordingly, the laboratory studies were designed to determine whether
the efficiency of washing could be enhanced significantly (compared to water
alone) by adding aqueous surfactants to the recharge water and recycling them
continuously.
The use of an aqueous nonionic surfactant pair for cleaning soil spiked
with PCBs, petroleum hydrocarbons, and chlorophenols was developed through
bench scale shaker table tests and larger scale soil column tests. The extent
of contaminant removal from the soil was 92 percent for the PCBs, using 0.75
percent each of Adsee 799® (Witco Chemical) and Hyonic NP-90® (Diamond Sham-
rock) in water. For the petroleum hydrocarbons, the removal with a 2 percent
aqueous solution of each surfactant was 93 percent. These removals are
orders of magnitude greater than obtained with just water washing and repre-
sent a significant improvement over existing in situ cleanup technology.
Treatability studies of the contaminated leachate were also performed to
investigate separating the surfactant from the contaminated leachate to allow
reuse of the surfactant. A method for separating the surfactant plus the con-
taminant from the leachate was developed; however, all attempts at removing
the surfactant alone proved unsuccessful.
Based upon the results of -the laboratory work, the aqueous surfactant
countermeasure is potentially useful for in situ cleanup of hydrophobic and
slightly hydrophilic organic contaminants in soil, and should he further
developed on a larger scale at a small contaminated site under carefully
controlled conditions. However, reuse of the surfactant is essential for
cost-effective application of this technology in the field. Accordingly, any
future work should investigate the use of other surfactants/surfactant combi-
nations that may be more amenable to separation.
This report was submitted in partial fulfillment of Contract No. 68-03-
3113 by SAIC/JRB Associates under the sponsorship of the U.S. Environmental
Protection Agency. This report covers the period from May 1982 to August
1985, and work was completed on August 23, 1985.
iv
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CONTENTS
Page
FOREWORD iii
ABSTRACT iv
FIGURES vi i
TABLES . viii
ABBREVIATIONS AND SYMBOLS ix
ACKNOWLEDGMENTS x
1. INTRODUCTION 1
2. INFORMATION SEARCH 3
2.1 Potential In Situ Countermeasures for Soils 9
2.1.1 HydTophobic Organics 9
2.1.2 Slightly Hydrophilic Organics 13
2.1.3 Hydrophilic Organics 14
2.1.4 Heavy Metals ; ... 14
2.2 Potential Pilot-Scale, and Full-Scale Tests
of Soil Countermeasures 15
2.2.1 Pilot-Scale Testing 15
2.2.2 Site of Opportunity Testing 17
3. CONCLUSIONS \ . 19
3.1 Effectiveness of the Surfactants 19
3.2 Effects of the Test Soil 20
3.3 Potential Target Contaminants 21
3.4 Effective Treatment Methods 21
4. RECOMMENDATIONS 23
4.1 Selecting Surfactants for In Situ Soil Cleanup 23
4.2 Testing Other Soils 23
4.3 Developing Leachate Treatment Methods 24
4.4 Further Countermeasure Development Before
Field Use 24
5. MATERIALS AND METHODS 25
5.1 Soil Selection and Characterization 25
5.2 Surfactant Screening Tests 29
5.3 Shaker Table Tests 29
5.4 Soil Column Tests 30
5.5 Analytical Procedures , .32
5.5.1 Extraction of Organics from Aqueous Media 32
5.5.2 Extraction of Organics from Soil 34
5.5.3 Instrumental Analysis 34
5.5.4 Internal Standards 35
5.6 Leachate Treatment 35
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6. RESULTS AND DISCUSSION 36
6.1 Soil Characteristics 36
6.2 Surfactant Selection 41
6.3 Preliminary Soil Column Experiments 42
6.4 Optimization of Surfactant Concentration 47
6.4.1 Shaker Table Tests 47
6.4.2 Column Tests 50
6.5 Evaluation of Leachate Treatment Techniques 50
6.5.1 Laboratory Tests of the Most Feasible
Treatment Alternatives 52
6.5.1.1 Foam Fractionation 53
6.5.1.2 Sorbent Adsorption 56
6.5.1.3 Surfactant Hydrolysis and Phase
Separation 56
6.5.1.4 Ultrafiltration 59
6.5.2 Less Feasible Treatment Alternatives 62
6.5.2.1 Flocculation/Coagulation/Sedimentation. . 62
6.5.2.2 Centrifugation 63
6.5.2.3 Solvent Extraction 63
6.6 Evaluation of Leachate Recycling 63
6.6.1' Column Tests With Untreated Leachate 63
6.6.2 Column Tests With Treated Leachate 64
REFERENCES 72
APPENDICES
A. Shaker Table Extraction Procedure. 77
B. Gas Chromatography Run Conditions and Run Programs .... 78
C. High Performance Liquid Chromatography Run Conditions
and Run* Programs 80
D. Calculations and Quality Control for Instrumental
Analysis 82
E. Metric Conversion Table 84
VI
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FIGURES
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Hammer Compaction Device in Glass Soil Column
Standard Soil Column Test Arrangement
Standard Grain Size Gradation Curve
Compaction Test Results: Moisture vs.
Density Relationship
Permeability vs. Density Relationship
Murban Soil Column Cleanup With 2 Percent of
Each Surfactant
PCB Soil Column Cleanup With 2 Percent of
Chlorinated Phenol Soil Column Cleanup With
2 Percent of Each Surfactant
PCB Shaker Table Recoveries vs. Surfactant Concentration. . . .
Murban Shaker Table Recoveries vs. Surfactant
PCB Soil Column Cleanup vs. Surfactant Concentration
Bench-Scale Foam Fractionation Column
Raw Leachate Recycling: PCB Column Soil Levels
Raw Leachate Recycling: Soil and Leachate Results
Treated Leachate Recycling: PCB Column Soil Levels
Treated Leachate Recycling: Soil and Leachate Levels
Page
31
33
37
-
39
40
44
45
46
48
49
51
54
60
65
66
68
69
VI 1
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TABLES
Number
^^^^^^^••^•^^•H
1
2
.•
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
»
Hazardous Soil Contaminants at Superfund Sites
Maximum Concentrations of Hydrophobic Organics
at 50 Superfund Sites
Maximum Concentrations of Slightly Hydrophilic
Organics at 50 Superfund Sites
Maximum Concentrations of Hydrophilic Organics
at 50 Superfund Sites
Potential In Situ Chemical Countermeasures
for Soils
Scale-Up Options for Testing In Situ Treatment Methods
Soils of Ten Region II Superfund Sites
Most Common Soil Subgroups at Region II
Superfund Sites
Grain Size Distribution by Wet Sieve and
Pipette Analyses
Surfactant Solubilities in Water .
Results of Surfactant Clay and Oil Dispersion Tests
Single Column Foam Fractionation Cleanup Results
Sorbent Batch Test Results
Base Hydrolysis Treatment of Leachate
Hydrolysis and Foam Fractionation Treatment
of Leachate
Ultrafiltration Test Results
PCB Levels in Hydrolysis and Sorbent Treated Leachate
PCB Mass Balance for Hydrolysis and Sorbent
Treated Leachate
Page
4
7
8
9
10
16
26
.
28
36
41
43
55
57
58
61
62
67
71
vm
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ABBREVIATIONS AND SYMBOLS
CEC
cm
cm/sec
cm?
01
ECD
EOR
EPG
ET6
FID
ft
9 .
g/cnH
g/g
GC
GC/MS
HCB
HPLC
hr
in
kg
LC
Ib
Ib/ft3
log P
m
mg
mg/1
ml
mm
m3/s
NaPEG
ng
nm
PBB
PCB
pcf
POTW
ppb
ppm
PVA
rpm
TOC
UV-VIS
ug
ug/ml
urn
ul
cation exchange capacity
centimeter
centimeters per second
square centimeters
deionized
electron capture detector
enhanced oil recovery
Emulsan Purified Grade from Petroferm
Emulsan Technical Grade from Petroferm
flame ionization detector
feet
gram
grams per cubic centimeter
grams per gram
gas chromatography
gas chromatography/mass spectrometry
hexachlorobenzene
high performance liquid chromatography
hour
inch
kilogram /
liter
liquid chromatography
pound
pounds per cubic foot
log (base 10) of octanol/water partition coefficient
meter
milligram
milligrams per liter
milliliter
millimeter
cubic meters per second
sodium polyethylene glycolate
nanogram
nanometer
polybro"minated biphenyl
polychlorinated biphenyl
pounds per cubic foot
publicly owned treatment works
parts per billion
parts per million
polyvinyl alcohol
revolutions per minute
total organic carbon
Ultraviolet-Vi sible
microgram
microgram per milliliter
micrometer
microliter
IX
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ACKNOWLEDGMENTS
This document was prepared by SAIC/JRB Associates for EPA's Office of
Research and Development in partial fulfillment of Contract No. 68-03-3113,
Task 29-1. Mr. Anthony N. Tafuri of the Hazardous Waste Engineering
Research Laboratory, Releases Control Branch, Edison, New Jersey, was the
Project Officer. The work presented in this document was performed by
Dr. William D. Ellis, Dr. James R. Payne, Mr. 6. Daniel McNabb, and
Mr. James Lambach of Science Applications International Corporation (SAIC),
with the assistance of Messrs. Daniel Baxter, Michael Beckel, Nicholas
DeSalvo, Ms. Dana Errett, Messrs. Gary Farmer, Michael Guttman, Joseph Rotola,
and Nicholas Trentacoste, all of SAIC, and Mr. James Nash of Mason and
Hanger - Silas Mason Company, Inc.
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SECTION 1
INTRODUCTION
The "Comprehensive Environmental Response, Compensation, and Liability
Act of 1980" (CERCLA or Superfund) recognizes the need to develop counter-
measures (mechanical devices, and other physical, chemical, and biological
agents) to mitigate the effects of hazardous substances that are released
into the environment and are needed to clean up inactive hazardous waste
disposal sites. One key countermeasure is the use of chemicals and other
additives that are intentionally introduced into the environment for the
purpose of controlling the hazardous substance. The indiscriminate use of
such agents, however, poses a distinct possibility that the release situation
could be made worse by the application of an additional chemical or other
additive.
The U.S. Environmental Protection Agency's Hazardous Waste Engineering
Research Laboratory has initiated a Chemical Counter-measures Program to
define technical criteria for the use of chemicals and other additives at
release situations of hazardous substances such that the combination of the
released substance plus the chemical or other additive, including any result-
ing reaction or change, results in the least overall harm to human health and
to the environment.
The Chemical Countermeasure Program has been designed to evaluate the
efficacy of in situ treatment of large volumes of subsurface soils, such as
found around uncontrolled hazardous waste sites, and treatment of large,
relatively quiescent water-bodies contaminated with spills of water-soluble
hazardous substances. For each situation, the following activities are
planned: a literature search to develop the body of existing theory and data;
laboratory studies on candidate chemicals to assess adherence to theory and
define likely candidates for full-scale testing; full-scale, controlled-
condition, reproducible tests to assess field operation possibilities; and
full-scale tests at a site requiring cleanup (i.e., a "site of opportunity").
This project, to develop the use of aqueous surfactants for in situ
washing of soils contaminated with hydrophobic (water insoluble) organics and
slightly hydrophilic (slightly water soluble) organics, was the first tech-
nique to be developed under the Chemical Counter-measures Program. Another
countermeasure for soils, the use of acids and chelating agents for washing
heavy metals from soils, is also being developed under the Program.
The Aqueous Surfactant Countermeasures Project included an information
search and laboratory development of the countermeasures. The results and
conclusions from the information search formed the basis for the laboratory
. 1
-------
development work. Similarly, the results and conclusions from the laboratory
work are intended to provide the basis for another project involving large-
scale testing of a chemical countermeasure, either in a large test tank (e.g.,
15 m x 15 m x 7.5 m deep), or under controlled conditions at a similarly
sized contaminated site or portion of a site of opportunity.
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SECTION 2
INFORMATION SEARCH
The information search was conducted to determine the nature and
quantities of hazardous soil contaminants at Superfund sites, and to assess
the applicability of existing technology to in situ treatment of contaminated
soils. To determine what types of soil contaminants requiring cleanup were
likely to be found at hazardous waste sites, a survey was made of the con-
taminants at 114 high priority Superfund sites. The classes of chemical
wastes found at the most sites were, in order of decreasing prevalence:
o Slightly water soluble organics (e.g., aromatic and halogenated
hydrocarbon solvents, chlorophenols)
o Heavy metal compounds
•*
o Hydrophobic organics (e.g., PCBs, aliphatic hydrocarbons).
The survey results are presented in Table 1. A variety of chemical
treatment methods were considered that might prove effective in cleaning up
soils contaminated with these wastes. However, methods for in situ chemical
treatment of soils will probably be feasible and practical for only certain
cleanup problems. They can be expected to be potentially most effective for
cleanups under the following conditions:
o The contamination is spread over a relatively large volume of
subsurface soil, e.g., 100 to 100,000 m3, at a depth of 1 to 10 m
o The contamination is not highly concentrated, e.g., not over
10,000 ppm total, or the highly concentrated portion of the site
has been removed or sealed off
o The contaminants can be dissolved or suspended in water, degraded to
nontoxic products, or rendered immobile, using chemicals that can be
carried in water to the zones of contamination.
For contamination less than 1 m deep, other methods such as landfarming
(surface tilling to promote aerobic microbial degradation of organics) would
probably be more practical. For highly contaminated zones of an uncontrolled
hazardous waste landfill or a spill site, methods such as excavation and
removal, or excavation and onsite treatment would probably be more practical
than in situ cleaning of the soil.
It was recognized that the use of aqueous surfactant solutions, which had
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TABLE 1. HAZARDOUS SOIL CONTAMINANTS AT SUPERFUND SITES
Number of
Sites
Total
Site
Score
Examples
Slightly Hydrophilic Organics
Aromatics
Benzene 9
Toluene 8
Xylene 5
Other aromatics 3
Halogenated hydrocarbons
Trichloroethylene 11
Ethylene dichloride 6
Vinyl chloride 4
Methylene chloride 3
Other halogenated 15
hydrocarbons "
Phenols 12
76
styrene, naphthalene
chloroform, trichloro
ethane, tetrachloro-
ethylene, trichlpro-
fluoromethane
picric acid, pentachloro-
phenol, creosote
Heavy Metal
Wastes
Chromium
Arsenic
Lead
Zinc
Cadmium
Iron
Copper
Mercury
Selenium
Nickel
Vanadium
Fly ash
Plating wastes
47
9
8
7
5
4
3
2
2
2
1
1
1
2
(continued)
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TABLE 1. HAZARDOUS SOIL CONTAMINANTS AT SUPERFUND SITES (Continued)
Number of
Sites
Total
Site
Score
Examples
Hydrophobia Organics
Polychlorinated biphenyls 15
Oil, grease 11
Volatile hydrocarbons 6
Chlorinated hydrocarbon 5
pesticides
Polynuclear anomalies 1
Other Inorganics
Cyanides 6
Acids 7
Alkalis 6
Radioactive wastes 3
Miscellaneous * 4
Hydrophilic Organics
Alcohols 4
Other hydrophilics 4
38
26
Varsol, hexane
endrin, lindane, DDT, 2,4,5-T,
dieldrin
sulfuric acid
lime, ammonia
uranium mining and purifica-
tion wastes, radium, tritium
beryllium, ooron hydride,
sulfides, asbestos
methyl, isopropyl, butyl
dioxane, bis(2-chloroethyl)
ether, urethane, rocket fuel
Unspecified Organic Solvents
and Other Organics
30 dioxin, dioxane, dyes,
pigments, inks, paints,
nitrobenzene
-------
been shown in laboratory tests to flush spilled gasoline from sand (Texas
Research Institute (TRI), 1979), might be used for in situ washing of slightly
hydrophilic (water soluble) and hydrophobia organics from soils. TRI used a
combination of equal parts of Witco Chemical's Richonate®-YLA, an anionic
surfactant, and Diamond Shamrock's Hyonic® NP-90, a nonionic surfactant.
To further verify which organic waste chemicals should be targeted for
countermeasures development, Field Investigation Team (FIT) summaries were
examined for the approximate order.of magnitude of the maximum concentrations
of organic contaminants in the soil and groundwater surrounding 50 Superfund
sites. The FIT Summaries provided data on the concentrations of the following
numbers of soil contaminants:
o 17 hydrophobic (water insoluble) organics
o 7 slightly hydrophilic (water soluble) organics
o 12 heavy/toxic metals
o 1 toxic_inorganic anion.
No soil concentrations of hydrophilic organics were found. The categories of
organic compounds were based on the logarithm of the octanol/water partition
coefficients (log'P) of the compounds, as follows:
o Hydrophobic organics: log P > 3.00
o Slightly hydrophilic organics: 1.00 < log P _< 3.00
o Hydrophilic organjcs: log P < 1.00.
The log P is an approximate measure of the tendency of a compound to adsorb
to soil rather than dissolve in water. Many hydrophobics, but no hydro-
philics, were detected in the soils, because hydrophilics tend to be washed
from soil by infiltrating rainwater. Hydrophobics had the highest levels of
all the organic contaminants, with ll^compounds averaging in the 1 to 100 ppm
range, and with chlordane exceeding 1,*000 ppm at one site. The soil concen-
trations of slightly hydrophilic compounds were in the range of 0.001 to 10
ppm; only two of the seven slightly hydrophilic compounds found, xylene and
phenol, were 1 ppm or above. Additional slightly hydrophilic organics were
found in the groundwater, because they also tend to be washed from soil. The
FIT Summary maximum concentration data are presented in Tables 2, 3, and 4.
Based on these findings, two hydrophobic and one slightly hydrophilic
pollutant groups were chosen as model contaminants for testing and development
of an aqueous surfactant counter-measure:
o High boiling Murban crude oil fraction containing aliphatic and
aromatic hydrocarbons
o PCB mixture in chlorobenzenes (Aroclor® 1260 transformer oil)
o Di-, tri-, and pentachlorophenols mixture.
A representative soil was chosen, based on a study of the characteristics of
soils at ten Superfund sites in EPA Region II. The countermeasure was labora-
tory-tested on the soil spiked with each of the three contaminant groups.
-------
TABLE 2. MAXIMUM CONCENTRATIONS OF HYDROPHOBIC ORGANICS
AT 50 SUPERFUND SITES*
SOIL NEAR SITES
GROUNDWATER
MAXIMUM NUMBER OF MAXIMUM
CONCEN- SITES CONCEN-
TRATIONS13 WHERE TRATIONSb
(ppm) DETECTED (ppm)
Chlordane 1
Dieldrin
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Fluoranthene
Pyrene
DDT
Bis(2-ethylhexyl) Phthal-ite
Di-n-butyl Phthalate
o-Dichlorobenzene
PCBs
Dioxin
Naphthalene
Oil
Grease
1 ,2 ,4-Tri chl orobenzene
Hexachlorobutadiene
Ethyl Benzene
Bis(2-ethylhexyl ) Adi pate
Cyclohexane
Benzo(b)pyrene
1,1,2-Trichlorotrifluoroethane
,000-10,000
10-100
10-100
10-100
10-100
10-100
10-100
10-100
1-100
1-10
1-10
0.1-10
0.1-1
c
c
c
c
-
-
-
-
-
-
1
1
1
1
1
1
1
2
3
1
2
7
1
1
1
1
1
-
-
-
-
-
-
-
-
-
c
c
-
-
-
0.1-10
-
c
10-100
-
100-1,000
1-10
-
-
10-100
1-1,000
1-10
c
c
c
NUMBER OF
SITES
WHERE
DETECTED
-
-
-
1
1
-
-
-
2
-
1
2
-
3
4
-
-
1
4
1
1
1
1
(a) Hydrophobic means log P > 3.00 (P = octanoT/water partition
coefficient).
(b) Order of magnitude ranges of the highest levels found at a site.
(c) Detected; concentration not reported.
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TABLE 3. MAXIMUM CONCENTRATIONS OF SLIGHTLY HYDROPHILIC
ORGANICS AT 50 SUPERFUND SITES*
SOIL NEAR SITES
Xylene
Phenol
Perchloroethylene
Methyl ene Chloride
Toluene
Trichloroethylene
Carbon Tetrachloride
Dichlorophenol
Vinylidene Chloride
Methyl Chloroform
Chloroform
Ethyl Chloride
Fl uorot ri chl oromethane
Methyl Isobutyl Ketone
Vinyl Chloride
Ethyl ene Di chloride
1 ,2-Di chl oroethyl ene
Benzene
1 ,2-Di phenyl hyd razi ne
Tetrahyd ropy ran
1,1-Dichloroethane
Chlorobenzene
2-Ethyl -4-methyl -1 ,3-di oxol ane
Isopropyl Ether
MAXIMUM
CONCEN-
TRATIONSb
(ppm)
1-10
1-10
c
c
c
c
c
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
NUMBER OF
SITES
WHERE
DETECTED
1
4 .
1
1
3
2
1
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
GROUNDWATER
MAXIMUM NUMBER OF
CONCEN- SITES
TRATIONSb WHERE
(ppm) DETECTED
0.1-100
0.01-0.1
0.1-100
0.01-100
0.01-100
0.001-100
0.1-1
10-100
10-100
0.001-100
0.001-100
1-10 •
1-10
1-10
0.1-10
0.01-10
0.01-10
0.001-10
0.1-1
0.1-1
0.01-1
0.01-0.1
c
c
4
3
5
6
9
10
1
4
4
8
1
4
4
•
9
1
4
3
1
1
(a) 'Slightly hydrophilic' means 1.00< log P < 3.00 (P = octanol/water
partition coefficient).
(b) Order of magnitude ranges of the highest levels found at a site.
(c) Detected; concentration not reported.
-------
TABLE 4. MAXIMUM CONCENTRATIONS OF HYDROPHILIC ORGANICS
AT 50 SUPERFUND SITES3
Acetone
Methyl Ethyl Ketone
Acrolein
Tetrahydrofuran
1,4-Dioxane
Acrylonitrile
Isobutanol
2-Propanol
SOIL
MAXIMUM
CONCEN-
TRATIONS'3
(ppm)
-
-
-
-
-
-
-
-
NEAR SITES
NUMBER OF
SITES
WHERE
DETECTED
- .
-
-
-
-
-
-
-
GROUNDWATER
MAXIMUM
CONCEN-
TRATIONS'3
(ppm)
0.01-10,000
1-10
0.1-1
0.1-1
0.01-0.1
c
c
c
NUMBER OF
SITES
WHERE
DETECTED
4
3
1
2
1
1
1
1
(aj "Hydrophilic" means log P < 1.00 (P = octanol/water partition
coefficient).
(b) Order of magnitude ranges of the highest levels found at a site.
(c) Detected; concentration not reported.
2.1 POTENTIAL IN SITU CHEMICAL COUNTERMEASURES FOR SOILS
The results of this information gathering on soil countermeasures are
shown in Table 5. The table lists the four categories of hazardous waste
materials previously identified as significant, several potential in situ
mitigation techniques for each hazardous waste category, and key citations to
the sources of information.
2.1,1 Hydrophobic Organics
The in situ treatment of hydrophobic organics can sometimes be accom-
plished by water injection/recovery systems using additives, followed by
final treatment above ground. In general, effectiveness of these treatment
-------
TABLE 5. POTENTIAL IN SITU CHEMICAL COUNTERMEASURES FOR SOILS
Hazardous Waste
In Situ Treatment
Selected References
Slightly hydrophilic
organics
Heavy metal wastes
• Water injection/recovery system
with surfactants
• Chemical and aerobic oxidation
• Sulfide precipitation
• Fixation with municipal refuse
• Water leaching to dissolve and/or
flush with injection/recovery
system
Texas Research Institute (1979, 1982b)
Dragun and Helling (1982)
Texas Research Institute (1982a)
Pohland et al. (1981, 1982)
USEPA (1979)
Huibregtse and Kastman (1978)
Myers et al. (1980)
Phung et al. (1982)
Kinman et al. (1982)
Jones and Malone (1982)
Epstein et al. (1978)
Fuller and Korte (1976)
Huibregtse et al. (1978)
Hydrophobic organics
Water injection/recovery system
with:
Surfactants
NaOCl, HO reactions
Micellar-polymer, e.g., petroleum
sulfonates - polyacrylamides
Hill et al. (1973)
Chou et al. (1982)
Klins et al. (1976)
(Continued)
-------
TABLE 5. (Continued)
Hazardous Waste
In Situ Treatment
Selected References
Hydrophobia organics
(continued)
Hydrophilic organics
Solvents
»
• Sodium polyethylene glycol reactant
•
• Water injection/recovery system with:
pH adjustment (buffering)
Surfactants
NaOCl,
reactions
Micellar-polymer , e.g., petroleum
sulfonates - polyacrylamides
Anderson et al. (1982)
Griffin and Chou (1980)
Pytlewski et al. (1980)
Laguros and Robertson (1978)
Hill et al. (1973)
Texas Research Institute (1979, 1982b)
Chou et al. (1982)
Klins et al. (1976)
-------
techniques is limited by the strong soil adsorption of hydrophobia organics
(Chou et al., 1981; Griffin and Chou, 1980). Therefore, any successful
recovery technique must first desorb the organic from the soil, either by
dissolving it in an appropriate micellar emulsion, dissolving it in a good
organic solvent, or destroying the soil's sorption capacity in order to flush
the hydrophobic contaminant to recovery.
A significant range of chemical additives, polymers, and surfactants has
been proposed to overcome the soil/organic adsorbence and flush hydrophobic
organics from contaminated soil at hazardous waste sites.
Law Engineering Testing Company (1982) completed an inventory of treat-
ment techniques applicable to gasoline-contaminated groundwater for the
American Petroleum Institute and proposed a number of treatment options for
further study. Texas Research Institute (1979) completed several laboratory
column and two-dimensional modeling studies on the use of surfactants to
enhance gasoline recovery from sand. The results showed that a combination
of commercial nonionic (Hyonic® PE-90) and anionic (Richonate®-YLA) surfac-
tants was effective in displacing gasoline from the column sand packs. Up to
40 percent of the residual gasoline after initial flooding was removed from
the sand using this surfactant combination.
Subsequently, Texas Research Institute (1982b) completed a study on
surfactant-enhanced gasoline recovery in a large-scale model aquifer. Three
surfactant application procedures were tested: a single application perco-
lated down through the sand bed, multiple applications by percolation, and
daily application into the water table. The percentages of gasoline removed
associated with each procedure were 6, 76, and 83,'respectively.
Texas Research Institute (1982a) also conducted studies on the microbial
degradation of underground gasoline by increasing available oxygen. The
Institute has also initiated research on the use of hydrogen peroxide to
provide oxygen for underground degradation of gasoline (C. Carlson, API,
personal communication, April 1982).
Griffin and Chou (1980) demonstrated that polybrominated biphenyls
(PBBs), which are similar in behavior to polychlorinated biphenyls (PCBs),
and hexachlorobenzene (HCB) are highly resistant to aqueous phase mobility
through earth materials. They are highly mobile in organic solvents such as
dioxane, and to a lesser extent in pure acetone and methanol. The solubility
of these materials in water can be directly correlated with dissolved organics
in the waters. Recent studies by Anderson et al. (1982) on the effect of
organic fluids on permeability of clay soil liners confirmed the significant
impact of acetone and methanol on clay soils. Acetone increased permeability,
probably as a result of soil dehydration, while methanol increased permea-
bility perhaps as a result of a decrease in interlayer spacing and accom-
panying structural changes. The use of these solvents appears promising as a
means to recover hazardous organics from uncontrolled releases, but treatment
above ground and subsequent disposal will still be necessary.
The enhanced oil recovery (EOR) studies of Hill et al. (1973) concen-
trated on displacing crude oil with a flooding medium and decreasing the
12
-------
"surface tension" between the phases, as do most EOR methods. The technique
might work for a soil highly contaminated with a hydrophobic hazardous waste.
As an example of tertiary EOR, Hill et al. (1973) described the development of
an aqueous surfactant system for recovering Far Springs crude oil in Benton,
Illinois. Petroleum sulfonate was selected as the surfactant because of the
wide range of types commercially available and their low cost. The addition
of sodium chloride to the 3.1 percent active surfactant further lowered the
interfacial tension between the crude oil and the aqueous solution. A
sequestering agent, sodium tripolyphosphate, was included to further improve
compatibility with Benton reservoir water. Once the surfactant-oil emulsion
slug was injected, a higher viscosity water wash containing a soluble polymer
(such as Dow Pusher 520) was introduced to achieve a stable plug flow
displacement. A final water drive completed the recovery. This tertiary
recovery approach is an example of using water with a combination of
surfactants as described earlier.
A unique approach for in situ removal of hazardous wastes from soils is
to employ micellar solution~Tlcoding, another tertiary oil recovery technique.
Micellar solution flooding is a process in which a solution containing a
surfactant-stabilized dispersion of water and hydrocarbons is injected into
the oil reservoir. The microemulsion is miscible with both the crude oil and
water. After injecting the micellar solution, a high viscosity mobility
buffer is injected to protect the emulsion from degradation by the drive
water. The composition of typical micellar material, e.g., Richburg Micellar
Solution, is as follows:
Water 68.03%
Diesel Oil . 17.97
Witco Sulfonate TRS 16 5.46
Witco Sulfonate TRS 40 5.51
Amyl Alcohol 2.37
Butyl Alcohol 0.66
For removal of various hazardous hydrophobic organics from the soil matrix,
the development of compatible micellar solutions for hazardous wastes could be
explored.
Chou et al. (1982) studied the effect of soluble salts and caustic soda
on the solubility and adsorption of hexachlorocyclopentadiene on soils. While
increasing the concentrations of brine, sodium chloride, and sodium hydroxide
caused an increase in adsorption, sodium hypochlorite caused a slight de-
crease. The salts causing the greatest depression in solubility also caused
the greatest increase in adsorption. No explanation was given for the reduced
adsorption caused by the sodium hypochlorite, but more intensive study may be
warranted.
2.1.2 Slightly Hydrophilic Organics
The in situ treatment of slightly hydrophilic organics will probably
require water injection/recovery systems using additives, followed by final
treatment above ground. The EOR methods presented above for hydrophobic
organics should also be applicable to slightly hydrophilic organics.
13
-------
To date, the primary efforts to remove benzene, toluene, and other
slightly water-soluble floating aromatics from releases to the saturated/
unsaturated interface has been by a water injection/recovery system. If
necessary, in a drawdown well, the floating organics are skimmed from the
groundwater while still in the well and recovered independently. The water
layer containing only dissolved organics is pumped from the well and the
organics are removed by a combination of air stripping plus activated carbon.
In a recent study, Oragun and Helling (1982) reported soil- and clay-
catalyzed reactions of organic chemicals, such as benzene and ethyl-benzene,
through free-radical oxidation. These reactions occur most often in a well-
aerated soil environment; therefore, they would be important if in situ
microbial oxidation were considered.
An approach for treating low water solubility chlorinated organics in
place is reaction with sodium polyethylene glycolates (NaPEG). Pytlewski et
al. (1980) first demonstrated in the laboratory that NaPEG could effectively
dechlorinate PCBs to form possibly reusable materials. At USEPA/HWERL-CINN,
Rogers has recently initiated laboratory and field studies on the use of NaPEG
as a spray-on reagent for treatment of chemically contaminated low moisture
soils. Using the. NaPEG reaction to treat chlorinated organic hazardous
material may be limited to aboveground destruction of partially dried chlor-
inated aromatic materials. Another possibility might be an in situ reaction
within a partially dried area around a chlorinated organic waste site. The
drying could be achieved by a combination of containment, including covering
with a surface cover, and underground forced air drying with removal of
vaporized organics prior to surface venting.
2.1.3 Hydrophilic Organics
Water injection/recovery systems for hydrophilic organic soil contam-
inants such as phenols and alcohols would not require surfactants or other
additives to recover the contaminants. The high water solubility of hydro-
philics is usually also accompanied by low adsorptivity on soil, due to the
polar nature of the molecules. The use of an alkali in the water could,
however, improve the solubility of phenols (which are weak acids) in water.
2.1.4 Heavy Metals
Releases of heavy metals from uncontrolled hazardous waste sites might be
mitigated using an injection/recovery system or an injection system alone to
precipitate the metals in place or to remove dissolved cations using a water
wash or a buffered water wash. In an earlier study, Huibregtse and Kastman
(1978) proposed using a water wash followed by dilute sodium sulfide to
precipitate metallic sulfides in place. However, it was only recently that
Pohland et al. (1981, 1982) substantiated the high stability of many heavy
metal sulfide precipitates in soils. Their results showed that the solubility
data, combined with the persistence of low levels of dissolved sulfide anion,
provided confirming evidence that the sulfide should be the controlling
precipitation mechanism in landfills. According to USEPA (1979), the low
solubility of the sulfide precipitate has resulted in increased acceptance of
14
-------
these techniques especially where more stringent control of the dissolved
metal is required. For soil treatment, a sodium sulfide or sodium hydro-
sulfide solution would be injected, with a buffer if necessary to maintain
sufficient sulfide ion concentration. An important potential concern is that
the sulfide precipitation will obstruct the soil pores and diminish the flow
rate. Reaction conditions would have to be adjusted to produce the finest
sulfide precipitates possible to minimize clogging of soil pores.
Another approach to stabilizing electroplating sludge is to combine
electroplating waste with municipal solids. Studies by Myers et al. (198U),
Phung et al. (1982), Kinman et al. (1982), and Jones and Malone (1982) have
been mostly favorable, although testing is still in progress and the chemistry
has not been thoroughly explained or documented.
Finally, leaching to remove heavy metal compounds using chelates or
acidified solutions and an injection/recovery system would be feasible.
However, removal of large quantities of heavy metal contaminants from a waste
site would require an efficient aboveground treatment system to concentrate
the spent leaching solutions before disposal.
f
2.2 POTENTIAL PILOT-SCALE, AND FULL-SCALE TESTS OF SOIL COUNTERMEASURES
The previous subsection focused on laboratory and pilot-scale findings
disclosed in the literature and appropriate ideas for laboratory testing.
Based on these findings, a range of scaled-up studies is discussed here that
can serve as models for studying in situ treatment of hazardous releases from
uncontrolled waste sites and spilTs.
2.2.1 Pilot-Scale Testing
Table 6 lists examples of scaled-up testing arrangements. The table
lists selected references that discuss the scale-up advantages and disad-
vantages. Table 6 has been subdivided into three types of scale-up: pilot
testing, in disturbed soils, modeling and verification using computer simula-
tion, and full-scale controlled condition testing in undisturbed soils.
To date, pilot-scale column tests [using columns 15 cm (6 in) to 305 cm
(10 ft) in diameter] have been oriented toward co-disposal of heavy metals
with municipal waste. The justification for using larger columns for these
plug flow tests has been the need to secure a large representative sample of
municipal refuse and the desire for better measurement and control of the
test procedure. De Poorter and Hakonson (1981) conducted tests with low
level radioactive wastes on a large scale for better measurement and sampling
without disturbing the long-term results of their low level contamination
test program. In general, the larger column tests have the advantages of
reduced wall effects; improved instrumentation, monitoring, and sampling
capability; adaptability to handle a heterogeneous waste mixture; and practi-
cality of carrying out the testing in an exposed, more natural environment.
The disadvantages of large column tests are that costs are high, testing is
nearly one-dimensional, and ultimately, more hazardous waste will have to be
disposed afterward.
15
-------
TABLE 6. SCALE-UP OPTIONS FOR TESTING IN SITU TREATMENT METHODS
Pilot Testing
(Disturbed soils primarily)
Pilot-scale column tests
(15-305 cm diameter)
Pilot-scale box tests
(Three-dimensional)
Modeling and Verification
Pilot~scale model
(Three-dimensional)
Selected References
Myers et al. (1980), Phung et al. (1982),
Kinman et al. (1982), Jones and Malone
(1982), De Poorter and Hakonson (1981)
Texas Research Institute (1979, 1982b)
Huibregtse et al. (1978)
Huibregtse and Kastman (1978)
Garon et al. (1980) (fireflooding-EOR]
Huygen and Lowry (1979) [steamflooding-EORJ
Full-Scale Testing
(Undisturbed soils)
Simulated release tests with surrogates
(In s^itu containment and treatment
unit as delivery/system)
Sites of opportunity
—Superfund sites
—Other uncontrolled hazardous
waste sites
—Spills
Rollinger (1978), Huibregtse and Kastman
(1978)
USEPA (1984a)
Harsh (1978), Uinn and Schulte (1982)
-------
Pilot-scale box tests provide the capability to conduct tests on a three-
dimensional scale. The Rexnord studies (Huibregtse et al., 1978; Huibregtse
and Kastman 1978) included tests in a sand box that was 122 cm (4 ft) deep,
107 cm (3.5 ft) wide, and 152 cm (5 ft) long. The very high recoveries of
contaminants from the testing suggest that the adsorption capacity of the sand
may have been very low. The Texas Research Institute studies (1979, 1982b) on
surfactant-enhanced gasoline recovery were conducted in a 3 m x 3 m x 1.2 m
deep sand-filled concrete tank with a nominal 0.3 m deep, 3 percent gradient
water table. These studies showed a greater spread of results with recovery
markedly improved by daily percolation or injection of surfactant.
In general, larger pilot-scale box tests such as those used by the Texas
Research Institute provided the advantages of testing in a facility with the
following capabilities:
o Three-dimensional tests at a scale approaching the field
b Water table with gradient
o Time cycle for weather conditions
o Sampling and monitoring easily implemented
o Leakage collection
o Moderate soil waste generated.
Conversely, only limited pilot-scale box testing has been conducted on the
larger scale (Texas Research Institute 1979, 1982b), so the interpretation of
results and scale-up value, although encouraging, cannot be compared with
other findings.
Three-dimensional pilot-scale model testing has been applied to fire-
flooding and steamflooding for enhanced oil recovery (see Table 6). One goal
of the testing was to establish a basic understanding of the mechanisms in
order to validate numerical models. Although the results were useful, the
modeling techniques may not directly apply to chemical counter-measures studies.
2.2.2 Site of Opportunity Testing
The application of chemical countermeasure techniques at a site of oppor-
tunity has been very limited. The main reasons are caution and scarcity of
experience in implementing in situ countermeasures to hazardous release
problems. For example, according to a USEPA survey completed by Neeley et
al. (1981), of 180 remedial actions (on 169 sites), there were only two
instances in which in situ treatment was used. In one case, lime was added
to a phenol waste and in another phosphates were added to accelerate biode-
gradation of a gasoline spill. Purging wells or interception ditches were
used in 15 examples, with or without surface treatment, to prevent ground-
water contamination from landfills.
A case study review on remedial actions at 23 hazardous waste sites has
been published by the EPA (1984). This included several studies on use of
slurry walls and direct recovery techniques for removing groundwater contam-
inants. Of considerable interest was the system used by O.H. Materials,
Findlay, OH, at the Goose Farm site in Plumstead Township, NJ. O.H. Materials
worked closely with the Department of Environmental Protection (N,)) and used
17
-------
a spray irrigation and well-point collection system with aboveground treat-
ment to remove the contaminants from the groundwater. The treatment consisted
of a carbon adsorption system to remove orga'nics, a clarifier, a four-cascade
aqueous carbon treatment system, aeration to strip organics not -treated by
carbon, and an effluent storage tank. The treated groundwater was reinjected.
Determining the magnitude and severity of groundwater contamination, particu-
larly in highly permeable soils (sand), may require installation of extensive
monitoring wells and the development and implementation of a staged cleanup.
Spills of hazardous waste have resulted in the rapid development and
implementation of technology to treat these wastes in place. Harsh (1978)
documented the in situ neutralization of acrylonitrile by first raising the
pH of the contaminated area above 10 with lime, and then spraying sodium
hypochlorite over the area. This treatment was successful, although the
water sprayed over the area in fighting the fire aggravated the contamination
problem.
The field techniques that would be applicable to in situ cleanup of soils
would be:
o Water and chemical additive injection or surface spraying, followed by
recovery using a drawdown well system (hydrodynamic control) or
possibly an interceptor trench, or French drains downgradient from
the source; leachate treatment would be conducted above ground
o in situ precipitation using an injection system with or without a
recovery-system
o in situ fixation process with an injection system if needed, but
probably no recovery, system
o in situ chemical reaction or degradation using an injection system
with or without a recovery system.
18
-------
SECTION 3
CONCLUSIONS
The laboratory research was conducted to determine whether significant
improvements to in situ cleanup of contaminated soils could be obtained using
aqueous surfactants rather than just "water (the only cleanup method demon-
strated to date). Further laboratory development of the surfactant counter-
measure included optimizing the concentration of surfactant used for cleanup,
and development of contaminated leachate treatment methods to enable reuse of
the surfactant.
The aqueous surfactant countermeas.ure was tested in the laboratory using
two basic methods. The first method was shaker table agitation, to quickly
determine the soil/aqueous surfactant partitioning of the model contaminants
under differing conditions. Shaker studies measured cleanup under conditions
permitting equilibration of the contaminants between soil and solution. After
the shaker table tests, cleanup was measured under gravity flow conditions
using soil column tests. These tests took much longer to run, but were
necessary to verify the cleanup behavior of the aqueous surfactant under con-
ditions resembling field use. Besides the optimum surfactant concentration,
the effects of leachate treatment and recycling were also studied using soil
column tests, to minimize the hazardous waste generated upon scale-up.
3.1 EFFECTIVENESS OF THE SURFACTANTS
Based on bench-scale tests designed to screen potential surfactants for
use as in situ soil washing enhancers, a 1:1 blend of Adsee® 799 (Witco Chem-
ical Corp.) and Hyonic® NP-90 (Diamond Shamrock) was found to be an effective
combination because of adequate solubility in water, minimal mobilization of
clay-sized soil fines (to maintain soil permeability), good oil dispersion,
and adequate biodegradability.
Shaker table and column experiments with this blend of surfactants dis-
solved in water at a total concentration of 4.0 percent (v/v), showed that
they were effective in removing 93 percent of the hydrocarbon and 98 percent
of the PCB pollutants from contaminated soil. These removals are orders of
magnitude greater than those obtained with just water washing and represent a
significant improvement to the efficiency of existing technology. Chlori-
nated phenols were readily removed from the test soil by water washing alone.
Shaker table experiments conducted to determine the optimum surfactant
concentration for soil cleanup, with PCB and petroleum hydrocarbon (Murban)
contaminated soils,, showed the optimum concentration to be 1.5.percent total
19
-------
surfactant. Individual surfactant concentrations of 0.25 percent or less
were unacceptable for effective soil washing, and surfactant concentrations
above 0.75 percent were excessive, since no significant enhancement of clean-
up resulted. In addition, similar partitioning between soil and surfactant
solution by the two pollutant types suggests that the results which would be
obtained in further large-scale experiments with the low toxicity hydrocarbons
in a fuel oil like Murban might reliably model the behavior of other more
toxic hydrophobic pollutant groups, such as PCBs.
The experiment which evaluated the effect of leachate recycling, with
treatment applied to the PCB leachate between cycles, showed that:
o Soil cleanup with 1.5 percent total surfactant is good, with less than
1 percent of the PCB remaining on the soil
o The product of hydrolysis represents a relatively small volume (about
12 percent of the total mass of leachate) of highly contaminated
material, which can be further treated by incineration, or disposed of
for a minimal cost
o The use of the same water for repeated cycles precludes the generation
of large volumes of waste leachate
o The final treated water after four cycles contains less than 0.0005
percent of the initial contamination encountered in the soil.
3.2 EFFECTS OF THE TEST SOIL
The efficiency of cleanup of the hydrophobic organic contaminated
Freehold soil by the aqueous surfactant solution was directly affected by the
low natural organic carbon content of the soil. The low TOC (0.12 percent)
represented little organic matter in the soil to adsorb the organic pollutants
spiked onto the soil, so the contaminant removal could be expected to be
relatively easy compared to a soil with, for example, a 1 percent TOC.
However, while the removal of hydrophobic organics from a 1 percent TOC soil
using the Adsee® 799 - Hyonic® NP-90 surfactant pair might be difficult, the
surfactants would probably be effective for removing chlorophenols, water
alone would not work nearly as well as with the low TOC Freehold soil.
The hydraulic conductivity of the Freehold soil as it was packed in the
soil columns, which was measured at 1.05 x 10~3 cm/sec, would he practical
for field implementation of the counter-measure. However, the time required
for .a pore volume of surfactant solution to flow through the soil should be
considered. With this hydraulic conductivity, if surface flooding were used
to obtain saturated conditions from the surface to a groundwater depth of
10 m (32.8 ft), and assuming a porosity of 50 percent, the maximum possible
hydraulic velocity would only be about 1.8 m/day, or 13 m/wk (42 ft/wk). And,
it would take 5.5 days for one pore volume of solution to flow through the
soil from surface to groundwater. A flow rate under similar conditions, with
a soil permeability of 1 x 10~4 cm/sec, would yield flow rates of about
1.2 m/wk, which is probably a practical lower limit for the method.
20
-------
The type of soil most likely to have the required hydraulic conductivity,
which is considered moderate permeability, would be a sandy soil or a sandy
loam, relatively low in silt and clay or being poorly sorted with respect to
grain size. If the soil had zones of low permeability, such as clay horizons
or clay lenses, the effects of even a low degree of clay particle mobilization
and redeposition by the surfactant could decrease flow rates and treatment
effectiveness significantly.
3.3 POTENTIAL TARGET CONTAMINANTS
The type of hazardous chemical for which the surfactant countermeasure
was more effective than just water included hydrophobic organics (the PCBs,
and the aliphatic hydrocarbons in the Murban fraction) and slightly hydro-
philic organics (the aromatic hydrocarbons in the Murban). The chemicals for
which the method would probably not be applicable would be heavy metal salts
and oxides, or cyanides. The method is not needed for slightly hydrophilic
organics, including chlorophenols, unless the soil had a higher natural TOC.
For hydrophilic organics such as low molecular weight alcohols, amines, and
acids, water alone will usually be sufficient for soil cleanup.
3.4 EFFECTIVE TREATMENT METHODS
Conservation of both water and surfactant prompted the investigation
of leachate reuse or recycling. Recycling of the untreated leachate is
unacceptable because portions of the soil that have been previously cleaned
will be recontaminated rapidly by the introduction of spent leachate.
The desire to recycle surfactants and the large volumes of contaminated
leachate generated during soil washing required investigations into the
treatment and concentration of the contaminants contained in the leachate.
The ideal treatment method would remove and concentrate the contaminants
while leaving the surfactants behind for further use. However, the same
chemical and physical properties of the surfactant mixture used that act so
well to extract the pollutants from the soil also inhibited separation of the
contaminants from the surfactants. Due to the high (percentage) level of
surfactant contained in the leachate, most of the treatment methods evaluated
were ineffective. The best treatment that could be obtained removed both
surfactants and pollutants, leaving clean water behind for possible reuse or
easy disposal. A summary of methods and their potential for leachate treat-
ment follows:
o Hydrolysis — Very effective as a primary treatment method for
removing both the surfactant and the contaminants.
o Foam fractionation — Unsuitable for primary treatment due to the
elevated (above the critical micelle concentration) levels of
surfactant in the leachate; quite suitable as a secondary treatment
step.
o Adsorption onto solids — Of eleven different sorbents tested,
including activated carbons, clays, etc., due to the surfactants
21
-------
present, none adsorbed contaminant well enough for primary treatment;
adsorption onto activated carbon should be effective as a secondary
treatment step after initial surfactant removal by other means (e.g.,
hydrolysis).
o Ultrafiltration -- After only limited testing, this approach appeared
to be another possible primary treatment method and should be evalua-
ted further.
Hydrolysis followed by adsorption onto activated carbon was the most
effective treatment method for leachate generated by the aqueous surfactant
countermeasure. However, none of the methods evaluated was successful in
effectively separating out the surfactants alone.
22
-------
SECTION 4
RECOMMENDATIONS
4.1 SELECTING SURFACTANTS FOR IN SITU SOIL CLEANUP
Additional surfactant tests are warranted before this technology can be
applied in the field. The surfactant combination used was water soluble, and
effective in soil column studies with both the Murban distillation fraction
and PCB pollutant groups. Furthermore, the combination allowed good, soil
percolation rates, as the mixture did not resuspend a significant amount of
the clay-sized particles in the soil, thereby inhibiting flow. These.charac-
teristics are definitely important; however, for this technology to be cost-
effective, reuse of the surfactant is equally important. Accordingly, it is
recommended that other surfactants/surfactant combinations be evaluated that
have the same "flushing" characteristics but are also more amenable to separa-
tion for reuse. Also, the surfactant screening tests for solubility, clay
dispersion, and soil dispersion should be followed by mutagenicity tests to
ascertain that any surfactants used for larger scale/field testing (and
ultimately in actual release situations) do not make the situation worse than
the original situation by the application of an additional chemical.
» *
During the soil column studies with these pol.lutant groups, there was a
marked decrease in soil percolation rates with time and accumulated leachate
volume. Therefore, in any laboratory, test tank, or controlled condition
field testing it seems advantageous to limit (or eliminate) any initial water
rinses and initiate aqueous surfactant treatment immediately to effect the
maximum soil decontamination before the percolation rate decreases. Also, it
may be possible to reduce the total amount of surfactant solution volume and
still obtain acceptable soil cleanup. Very significant soil cleanup of
Murban hydrocarbons and PCB mixtures was obtained after as little as five pore
volumes of aqueous surfactant had passed through the soil columns.
4.2 TESTING OTHER SOILS
The total organic carbon in the Freehold soil was very low (0.12 percent
by weight), and numerous studies (Lyman et al., 1982; Karickhoff, 1981;
Tinsely, 1980) have indicated that the percentage of organic carbon has a
critical effect on the degree of pollutant adsorption. Furthermore, the
cation exchange capacity (CEC) was 8.6 milliequivalents per 100 gms, an
extremely low value, confirming the absence of mineralogic clay in the soil.
If additional laboratory or tank testing were to he undertaken, a second soil
type with greater percentages of organic carbon, with mineralogic clay, and/or
higher CEC values might be considered to expand the overall applicability of
the program results to a broader variety of soil matrices. .
23
-------
4.3 DEVELOPING LEACHATE TREATMENT METHODS
Additional efforts should be directed toward optimizing feasible and
cost-effective methods of leachate treatment and in particular separation
of the surfactant for reuse. Specifically, ultrafiltration appears promising
and warrants further investigation; foam fractionation should also be inves-
tigated further. The use of equipment and technologies already existent
should be examined in greater detail to minimize scale-up costs.
4.4 FURTHER COUNTERMEASURE DEVELOPMENT BEFORE FIELD USE
The testing of a new technique, in which hazardous contaminants are
rendered more mobile, presents a potentially greater environmental threat
unless the tests can be readily stopped at any point as required, to permit
the immediate remedy of any failure by established techniques. Because the
aqueous surfactant countermeasure is still developmental, the field tests
should be conducted on a reduced scale until the procedures are proven work-
able and the important parameters are understood and controlled.
The laboratory tests have established the effectiveness of the technique
for soil cleanup sufficiently to justify tests on a larger scale. Pilot-
scale (test tank) possibilities for testing the countermeasure are described
under the Information Search Section. Pilot-scale testing would require the
use of disturbed soil, and would probably not further the development of the
method as much as controlled condition field testing at a site of opportunity.
An appropriate site for field testing would have the following charac-
teristics:
o Moderate to high permeability (coefficient of permeability of
10"4 cm/sec or better)
o Small size (e.g., 30 m x 30 m x 10 m deep)
o Minimal immediate threat to drinking water supplies
o Hydrophobic and/or slightly hydrophilic organic contaminants
o Concentrated contamination source removed or controlled
o Low to moderate natural organic matter content in soil (TOC 0.5-2
percent).
If either small sites, or physically separated sections of a large site
(e.g., with a slurry or grout wall) were selected, the aqueous surfactant
countermeasure described in this report could be applied, tested further, and
improved to a point of full field countermeasure applicability.
The hydrostatic pressure during all of the column tests was relatively
low: about 60 cm. The flow rate could be increased significantly, thereby
reducing treatment times, if the hydrostatic head of the treatment solution
were greater.
24
-------
SECTION 5
MATERIALS AND METHODS
5.1 SOIL SELECTION AND CHARACTERIZATION
In choosing a soil to be used in the surfactant washing tests, the
applicability of the results to actual field situations was a primary con-
sideration. The selection process included identifying the native soils at
each of the Region II Superfund sites for which data was available, deter-
mining the most commonly occurring soil type series, and locating a soil of
the same soil taxonomic classification which could be excavated and used in
the testing experiment. The limited availablity of published soil surveys
and the fact that some of the sites were mapped only as "urban land," which
indicated that the original soil had been altered or removed, reduced the
number of Superfund sites for which information could be gathered to 10 sites.
Supplementary data for the D'Imperio, Price, and Lipari Landfill sites were
obtained from the Region II Superfund site investigation files located in the
New York City Regional office.
Each site's exact location was ascertained using topographic maps and
information supplied in the Field Investigation Team (FIT) report summaries.
Next the site was located on soils maps contained within Soil Survey Reports
compiled by the U.S. Department of Agriculture (USDA) Soil Conservation
Service (SCS). The soils indicated within a radius of two times the square
root of the total area of each site were identified. If more than five
different soil series were present, the five major soils in terms of area
were chosen. Table 7 lists the soils series as well as the taxonomic classi-
fication to the subgroup level according to Soil Taxonomy (Soil Survey Staff,
1975) for the soils encountered at the Region II Superfund sites. Also
outlined within Table 7 are the textural classes and permeability ranges
for each soil series. The most commonly occurring classification was Typic
Hapludults, fine- to coarse-loamy. An explanation of the nomenclature is as
follows:
Typic Representative of the great group
Hapl Great group element meaning "simple or minimum horizons"
ud Suborder element meaning "of humid climate"
ults Of the order Ultisols: the soils have an argillic horizon,
i.e., a zone of clay accumulation, and have low base saturation.
The coarse-loamy textural class indicates a soil with a low content of clay
(less than 18 percent) and a high content (more than 15 percent) of fine,
25
-------
TABLE 7. SOILS OF TEN REGION II SUPERFUND SITES
Sice
Soil Series
Taxonoralc Classification Texture
Permeability*
Liparl Landfill
Aura
Sassafras
Typlc Hapludulte
Typlc Hapludults
fine-loamy
fine-loamy
moderately slow to moderate
moderate to moderately rapid
D' Iraperio
ro
Price
Facet Enterprises
Love Canal
Matawan
Klej
Woodsiown
Pocomoke
Sassafras
Downer
Klej
Sassafras
Howard
Canandalgua
Madalla
Bridgeport Brothers Sassafras
Downer
Dragston
Klej
Woodstown
Molra
Niag.ra Co. Refuse
Coveytown
Scarboro
Wai pole
Eiopeyvl He
Faliey
Canundaigua
Kaynharo
Aqulc Hapludults
Aqulc Quartztpsaraments
Aqulc Hapludults
Typlc Umbraquults
Typlc Hapludults
Typlc Hapludults
Aqulc Quartzlpsaroroents
Typlc Hapludults
Clossoborlc Hapludalfs
Molllc Haplaquepts
Molllc Ochraqualfs
Typlc Hapludults
Typlc Hapludults
Aqulc Hapludults
Aqulc Quartzlpsamments
Aquic Hapludults
Aerlc Haplaquents
Hlstlc Humaquepts
Aerlc Haplaquepts
Aquic Fraglorthods
Aquentlc llaplorthods
Molllc Haplaquepts
Aerlc Haplaquepts
fine-loamy
sandy
fine-loamy
coarse-loamy
fine-loamy
coarse-loamy
sandy .
fine-loamy
loamy-skeletal
flne-sllty
fine (30-60Z clay)
fine-loamy
coarse-loamy
coarse-loamy
sandy
fine-loamy
sandy/loam
sandy
sandy
loam
sandy-skeletal
fine-sllty
coarse-sllty
moderately slow to moderate
rapid to very rapid
moderate to very rapid
moderate to moderately rapid
moderate to moderately rapid
moderate to moderately rapid
moderate
moderate to moderately rapid
moderate
moderate
moderate
moderate to moderately rapid
moderate to moderately rapid
moderate
moderate
moderate
moderately rapid to rapid
rapid to very rapid
moderately rapid
slow
rapid
moderate
moderate to moderately rapid
(continued)
-------
TABLE 7. (continued)
Site
Soil Series
Taxonoralc Classification Texture
Permeability*
Pollution Abatement Scrlba
Services Ira
Sodus
Aerie Fraglaquepts
Typlc Fraglochrepts
Typic Fraglochrepts
coarse-loamy
coarse-loamy
coarse-loamy
slow
slow
slow
Helen Kramer
Landfill
Freehold
Typlc Hapludults
fine-loamy
moderate
ro
*Terms used to describe permeability are as follows:
Very slow <4.2 x 10~5 cm/sec
Slow 4.2 x Id'5 to 1.4 x 10-4 cm/sec
Moderately Slow 1.4 x 10'4 to 4.2 x 10~4 cm/sec
Moderate 4.2 x 1C)-4 to 1.4 x 10~3 cm/sec
Moderately Rapid 1.4 x lO'3 to 4.2 x 10~3 cm/sec
Rapid 4.2 x 10~3 to 1.4 x 10-2 cm/sec
Very rapid >1.4 x 10~2 cm/sec
-------
medium, and coarse sands plus coarse fragments up to three inches. Fine-loamy
is the same as above except that clay content is 18 to 35 percent.' Table 8
outlines the frequency of occurrence of the various soil subgroups and
permeability ranges for each.
TABLE 8. MOST COMMON SOIL SUBGROUPS AT REGION II SUPERFUND SITES
Soil Subgroup
Range of Permeability
Frequency of
Occurrence *
Typic Hapludults
Aquic Hapludults
Aquic Quartzipsamments
Mollic Haplaquepts
Aerie Haplaquepts
Typic Fragiochrepts
Typic Umbraquults
Aerie Haplaquents
Aquentic Haplorthods
Mollic Ochraqualfs
Aerie Fragiaquepts
Typic Rhodudults
Hi stic Humaquepts
Glossoboric Hapludalfs
moderately slow to moderately rapid
moderately slow to very rapid
moderate
moderate
moderate to moderately rapid
slow
moderate to moderately rapid
moderately rap.id to rapid
rapid
moderate
slow
moderate
rapid to very rapid
r-'
moderate
10
4
3
2
2
2
1
1
1
1
1
1
1
1
*of 10 sites studied
In addition to taxonomic classification, other factors were considered in
choosing the soil for surfactant tests. A permeability rating of 10-2 to
10~4 cm/sec was considered an acceptable range; less permeable soils would
take too long to test. Also, the soil could not contain significant amounts
of the clay of marine origin called glauconite. The glauconitic soils found
in the Coastal Plain of Region II are known to lose their permeability upon
wetting.
28
-------
The soil selected for use in the study was a Freehold series typic
hapludult from Clarksburg, New Jersey. Initial characterization of the soil,
consisting of grain size analyses, determination of natural moisture content,
compaction tests, and permeability vs density tests, was conducted by Raamot
Associates, Parlin, NJ. Mineralogy by X-ray diffraction was undertaken by
Technology and Materials Company, Santa Barbara, CA, on a Phillips Electronics
X-ray diffractometer; the X-ray diffraction charts were interpreted by compari-
son with standard diffraction file data. The total organic carbon content
(TOC) was measured by Laucks Testing Laboratories, Inc., Seattle, WA, according
to EPA Method 415.1. Laucks Testing Laboratories, Inc., also determined the
cation exchange capacity of the soil using the method of Jackson (1960).
5.2 SURFACTANT SCREENING TESTS
The surfactant combination used by Texas Research Institute for flushing
gasoline from sand (TRI, 1979), Richonate®-YLA and Hyonic® NP-90 (formerly
called Hyonic® PE-90), was screened along with several other surfactants and
surfactant combinations for three critical characteristics:
o Water solubility (deionized water)
o Clay particle dispersion
o Oil dispersion.
Any candidate surfactant must dissolve in water to form an effective solution
for in situ cleanup. Deionized water was used to test the solubility because
it was available in quantity and had constant physical and chemical charac-
teristics. The laboratory tap water varied greatly in salts content from week
to week.
Preliminary soil column tests with the Richonate®-YLA and Hyonic1® NP-90
surfactant combination showed constantly decreasing flow rates; this was
attributed to clay-sized particle mobilization and redeposition by one or both
surfactants. To minimize this effect, and to assist in selection of another
surfactant combination other than the one used by TRI, screening tests for
clay dispersion were run. A 250 mg sample of the Freehold soil was shaken on
a wrist action shaker with 10 ml of the surfactant solution for 5 minutes in a
15 ml screwcap vial, then allowed to settle overnight. The cloudiness of the
solution was noted as an indication that the clay was still suspended.
The ability of the chosen surfactant(s) to disperse a hydrophobic organic
like an oil (Prudhoe Bay crude was used for the test) was considered an
accurate model for the ability to clean organics from soil. A 50 ml aliquot
of the surfactant solution was swirled in a 100 ml beaker with two drops of
oil , and the extent of oil dispersion was determined by the cloudiness and
darkness of the solution.
5.3 SHAKER TABLE TESTS
To represent the approximate levels found at waste sites (Section 2,
Information Search), soils were spiked with 100 ppm PCB, 1000 ppm Murban
29
-------
distillation fraction, and 30 ppm chlorophenol for shaker table studies by
the following procedure. The amount of soil necessary for one set of shaker
table samples was spread evenly in aluminum pans to a depth of approximately
1.3 cm (0.5 in) and spiked with an aerosol spray of the required amount of
contaminant mixture dissolved in methylene chloride. The methylene chloride
was allowed to evaporate, and the soil was mixed by stirring in the pans,
then stored in sealed containers. Approximately 100 g of the contaminated
soil was weighed into each of the 500 ml Teflon jars. In preparing soil for
flow-through column studies each of the nine portions of soil (lifts) of
775 g each was spiked as described above and then packed into the column as
described in the next section.
Shaker table partitioning experiments were conducted to determine the
effects of various surfactant concentrations on soil cleanup. After spiking
the Freehold soil with PCBs or hydrocarbons, various concentrations of sur-
factants in water were used to wash the soil under well-shaken conditions
allowing equilibration of the contaminants between the soil and the surfactant
solution.
The procedure for conducting the shaker table tests was as follows. One
hundred grams of contaminated soil was agitated with 200 ml of the appropriate
surfactant concentration on a shaker table for 1 hour, then centrifuged for
15 minutes at 2500 revolutions per minute (rpm). The leachate was decanted
and both soil and leachate were analyzed for the contaminants. Leachates and
soils were extracted and analyzed according to the methods described in
Section 5.5, Analytical Procedures. The results of these experiments can be
found in Section 6.3, Preliminary Soil Column Experiments.
5.4 SOIL COLUMN TESTS
The custom fabricated soil columns used in this study were 7.6 cm (3 in)
I.D. by 150 cm (5 ft) glass columns. Both ends of the column were sealed with
nippled glass caps. A Teflon 0-ring, placed between the glass column and cap,
sealed the two surfaces as they were crimped together by an adjustable
stainless steel jacket. Teflon tubes connected to the end caps allowed the
introduction of the aqueous surfactant solutions and the collection of
leachates.
At the initiation of each experiment, using one pollutant mixture, a
series of columns was prepared. Contaminated soil was packed into the columns
using the following procedure. After leak testing the column with deionized
water, a plug of glass wool was inserted at the top of the column and pushed
down to.the bottom using the compaction device. A lift of soil weighing
approximately 775 g was then added to the column and packed to a height of
10 cm (4 in) using a custom-made controlled drop-hammer compactor designed to
fit inside the column. Figure 1 shows the addition and compaction of one lift
of contaminated soil. Following compaction of each 10 cm lift, the soil was
tested with a pocket penetrometer (Soil Test Model CL-7000, Soil Test, Inc.)
modified for use in the 7.6 cm diameter columns. To ensure better cohesion
between layers, the upper 0.6 cm (0.25 in) of each plug was scarified before
the next lift of soil was placed.
30
-------
Reproduced from
best available copy.
FIGURE 1. HAMMER COMPACTION DEVICE IN GLASS SOIL COLUMN
31
-------
Soil weight, packing depth, number of taps required, and compaction
data were monitored for uniformity as each column was packed. The soil was
packed to a total height of 90 cm (3 ft) and compacted to a density of
1.68-1.76 g/cm3 (105-110 lbs/ft3), yielding a percolation rate of 3 to 5 x
10~4 cm/sec, which was comparable to the natural permeability measured by ASTM
methods (Raamot Associates, 1983). Compaction/density and percolation rate
testing in the laboratory demonstrated that this procedure was reproducible.
Figure 2 shows a set of packed soil columns, with leachate receiving carboys
below, in the standard arrangement for column tests.
The first test, a preliminary experiment with columns of each of the
three contaminant mixtures, tested water followed by 4 percent total surfac-
tant for soil cleanup. Four sets of soil column tests were conducted using
Murban hydrocarbons, PCBs, and/or chlorophenols spiked soil. The second test
was designed to assure that the optimum surfactant concentration under gra-
vity flow conditions was not significantly different from that established
under equilibrium conditions. The third column test evaluated the effect of
washing soil with recycled, untreated leachate compared to soil washing with
fresh surfactant only. The fourth column test evaluated the effects of
washing soil with recycled, treated leachate. In each round of column exper-
iments the soil spiking and column packing procedures were identical.
Column tests were run by allowing the surfactant mixture to percolate
through the soil column under a 30 cm constant head. Leachate was collected
in LO liter glass carboys; columns were sacrificed after the appropriate
number of passes had been administered (one pass was defined as three to four
pore volumes). Column sacrifice consisted of allowing the column to drain
overnight then scraping the top,-middle, and bottom sections out using a
specially designed tool. The individual sections from the columns were
homogenized prior to extraction; leachate and soil analyses were conducted as
described in Section 5.5, Analytical Procedures. The experimental procedures
for the four column tests differed, therefore, they are described in detail
preceding the results and discussion of each experiment (see Section 6,
Results and Discussion).
5.5 ANALYTICAL PROCEDURES
The analysis of contaminated soils and aqueous leachates involved solvent
extraction, liquid chromatography (fractionation into aliphatic, aromatic, and
polar fractions) and instrumental analysis by a combination of flame ioniza-
tion detector gas chromatography (FID-GC), electron capture detector gas
chromatography (ECD-GC), and high performance liquid chromatography (HPLC).
Extraction procedures for the two types of samples that were generated by this
study are presented in the next two subsections.
5.5.1 Extraction of Organics from Aqueous Media
The protocols employed for priority pollutant sample preparation
involving aqueous media were EPA Methods 608 and 625 (Federal Register, 1979).
32
-------
Reproduced from ^*»
best available copy.
FIGURE 2. STANDARD SOIL COLUMN
TEST ARRANGEMENT
33
-------
For leachates in which aromatic hydrocarbons or PCBs were present, EPA
Method 608 was followed. Both contaminant types were carried through the
sodium sulfate drying step, after which the Murban hydrocarbon extract was
subjected to silica gel column liquid chromatography (LC). This LC fractiona-
tion scheme is described in detail in subsection 5.5.2, Extraction of Organics
from Soil. In this manner, the separate behavior of aliphatic and aromatic
Murbaji hydrocarbons during shaker table equilibration and soil column leaching
could be observed. The Murban hydrocarbon contaminant extracts were analyzed
by FID-GC.
The extract from the PCB (Arochlor® 1260) contaminant leachate was
analyzed by ECD-GC immediately after the sodium sulfate drying step, without
silica gel fractionation.
For the leachate-containing chlorinated phenols, EPA Method 625 was
utilized. Because the concentration of specific phenolic compounds was being
monitored, the base/neutral extraction was omitted. The leachate was.
subjected to the Method 625 acid/phenol extraction step only, and then
analyzed by HPLC.
5.5.2 Extraction of Organics from Soil
Soil samples were prepared for pollutant analysis utilizing a rigorous
shaker table extraction procedure which is simildr to that described by
Payne et al. (1978) and Brown et al. (1980), and which has been shown to
yield comparable results to Soxhlet extraction (MacLeod et al., 1982;
MacLeod and Fischer, 1980; Payne et al., 1979). This procedure is
presented in Appendix A. • "
The extracts were then concentrated to approximately 1 ml using a K-D
evaporator and, for Murban extracts, solvent exchanged to hexane in prepa-
ration for silica gel LC separation and analysis by FID-GC. PCB and phenol
extracts were analyzed by ECD-GC and HPLC, respectively. No further cleanup
steps were necessary for these two pollutant groups.
5.5.3 Instrumental Analysis
The GC and HPLC run conditions and run program specifications, necessary
for analyzing each of the three types of contaminants and the surfactants,
are presented in Appendix B.
A Hewlett Packard 1084B HPLC was used to analyze for phenols in soil
column sediments and leachates. The HPLC was equipped with an HP 79841A Auto-
sampler with a 60 vial sampling capacity. The HPLC was interfaced to a Waters
Model 440 absorbance detector set at a wavelength of 280 nm.
Quantifying the surfactants in leachates and treated leachates was
accomplished by UV spectroscopy on a Hitachi Model 100-80 UV-VIS spectro-
photometer. Linear response was established using a deuterium lamp at a
wavelength of 271 nm in the double beam mode of operation. The linear range
34
-------
for total surfactants (Adsee® 799 + Hyonic® NP-90) was determined to be from
0.001 to 0.20 percent with deionized (DI) water in the reference cell.
Quality control tests were completed to evaluate the extent of inter-
ferences due to the presence of PCBs, or the effects of leachate contact with
soil, filtration, or centrifugation. Interferences due to these effects were
minimal.
5.5.4 Internal Standards
Every sample to be analyzed was spiked with an internal standard mixture.
The standards were added to the raw samples in a precise and quantitative
manner. They were carried throughout the analytical scheme to check and
monitor the recoveries of the compound classes they represented. The main
consideration when selecting the compounds to be used as internal standards
was their solubility and chromatographic similarity to the compounds of
interest; i.e.:
o M-Decylcyclohexane (aliphatic) and hexamethylbenzene (aromatic) were
. used as internal standards for the Murban hydrocarbon contaminant
samples.
o The pesticide Lindane was the internal standard for PCB samples. It
behaved similarly to Aroclor® 1260 and gave a separate, distinct peak
during GC analysis.
o For the chlorinated phenol test mixture (di-, tri-, and penta-
chlorophenols), the internal standard was 4-chloro-3- methyl phenol. It
was an ideal surrogate compound since it exhibited the same chemical
behavior as the other chlorophenols, but was not present in the
prespiked sample.
The amounts of standards added were in the range of concentrations
expected for the analytes. Utilization of these spiked materials as refer-
ences in analysis of the pollutants of similar structures was necessary for
reproducible determinations in samples of widely varying matrices (i.e.,
aqueous leachate, leachate plus surfactant, and soils).
5.6 LEACHATE TREATMENT
The methods of leachate treatment, which were investigated, included
hydrolysis, solid adsorption, foam fractionation, and ultrafiltration. The
materials and methods used during these short investigations are presented
with the results in subsection 6.4, Evaluation of Leachate Treatment Tech-
niques, to allow easier understanding of the effects that the methods had
upon the results.
35
-------
SECTION 6
RESULTS AND DISCUSSION
6.1 SOIL CHARACTERISTICS
Subsection 5.1, Soil Selection and Characterization, describes how a
Freehold series typic hapludult soil was selected for the study. Prior to
undertaking shaker table or column experiments, the soil was characterized by
grain size, density, percent moisture, porosity, mineralogy by X-ray
diffraction, cation exchange capacity (CEC), and total organic carbon (TUC).
Preliminary soil characterizations were completed by Raamot Associates
(1983). Grain size analyses, determinations of natural moisture content, and
modified Proctor compaction tests were undertaken to develop moisture/density
characteristics and determine optimum moisture content for permeability
testing at various densities. Figure 3 presents the cjrain size gradation
curve of the Freehold soil following dry sieve analysis. The soil was
relatively sandy (83 percent) and low in silt/clay (10 percent). Although the
soil was packed in the columns without wetting, its. behavior during column
tests under saturated conditions was predictable more, accurately by wet
sieve grain size analysis. Table 9 presents the grain size distribution
obtained by wet sieve and pipet analyses.
TABLE 9. GRAIN SIZE DISTRIBUTION BY WET SIEVE AND PIPETTE ANALYSIS
Class
Gravel
Sand
Silt
Clay
Size Range
(urn)
>1000
62-1000
8-62
<8
Mass
(percent)
16
61
15
8
Estimated Surface Area
(percent)
<0.5
5
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61
36
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As the data illustrate, compared to the dry sieve analyses, significantly
higher levels of percent fines (silt, 15 percent and clay, 8 percent) were
observed in the wet sieve analyses. The fines tend to limit soil perme-
ability. Approximately 95 percent of the theoretical surface area is
represented by these fine particle sizes. The tendency of a soil to adsorb
organic contaminants is a function of the soil surface area available for
adsorption, and of the soil natural organic matter, which also adsorbs to, as
well as provides adsorptive surface.
Figure 4 presents the compaction test report showing the moisture versus
density relationship for the soil, and the maximum compaction of approximately
1.89 g/cm3 (118 Ib/ft3) at 11 percent moisture content. The compaction test
followed the modified Proctor method. Permeability vs density data are
presented in Figure 5.
To determine the effect of the degree of soil compaction on the perco-
lation rates through the soil.columns being tested, the soil was packed as
received, with a natural moisture content of 11 percent. By compacting the
soil in the columns to a density of 1.68 g/cm^ (105 Ib/ft3), a percolation
rate of 1.5 x 10~3 cm/sec (i.e., discharge rate divided by column area) was
obtained under a constant 60 cm head. The soil column percolation rate
measurements provide an estimate of the maximum expected flow rate under
laboratory or field conditions. At greater soil densities, the percolation
rate (which is proportional to permeability at a given hydraulic head and depth
of soil) would be correspondingly lower.
To determine the mineralogical composition of the Freehold soil, X-ray
diffraction studies were undertaken by Technology of Materials Company. The
sample was prepared by grinding and sieving an aliquot of soil to 200 mesh
particle size. This powder was then run in a Phillips Electronics X-ray
diffractometer, equipped with a crystal monochrometer. The X-ray diffraction
charts were analyzed and phase identifications were made by comparison with
standard diffraction data files. The results showed quartz and feldspar to be
the only measurable constituents. Quartz was the major phase, representing at
least 98 percent of the total weight. No measurable amounts of any clay
minerals appeared in the native sample or in a subsample of just the clay
sized particles. The color of the Freehold soil suggested iron carbonate or a
hydrated iron oxide; however, this color is evidently due to an amorphous iron
oxy-hydroxide or hydroxide as no measurable peaks were found representing the
suspected phases.
The cation exchange capacity (CEC) of the soil was also determined by
Laucks Testing Laboratories, Inc. The total exchangeable metallic cations,
•and the exchangeable hydrogen were each determined, and the results were
added to yield the total CEC. The result was 8.6 milliequivalents per 100
gms, an extremely low value, confirming the absence of mineralogic clay in
the soil. The absence of mineral clay and the low CEC could be expected to
allow removal of polar organic contaminants from the soil more easily than
from a more clayey soil.
The total organic carbon content (TOC) of the soil, as measured by Laucks
Testing Laboratories, Inc., (using a Oohrmann DC 80 TOC Analyzer) was 0.12
percent by weight. This relatively low level of organic matter in the soil
38
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|0 «0 l« *l 01 « al AIM 000* 0001
OHAIN SIZE IN UILLIMEIINS
L
I 1
• AND
SILT OH CLAY
gStSSS SS Z i
PERCENT COARJER BT WEI6HT
».B2 20 09* 02S 0074 UIIII»iUil
g u Hoi 10 1O iO ZOO Slixi
Clirkiturg Pit
Reil-froun cm
* I" SAND. lrtc»* £l«r«» SIM. Irtce t finvil.
FIGURE 4. COMPACTION TEST RESULTS:
MOISTURE VS. DENSITY RELATIONSHIP
-------
1.0 I ID'J
ui
I
.0 I ID'4
UI
o
.0 I 10-'
'a' lot 10; lot 101 no ill lit in in IK 114 MI \\tt.t.t.
B9.o a?.t »o.i *i.t ii.4 n.i M.I M.I is.i tt.t »;.i 9a.i «.i loo.o i
DRY UNIT WEIGHT, U , (pcf)
COMPACTION (Porctn! Modified Proctor Oeniily )
PERMEABILITY VS. DENSITY
SOURCE :a*i«siu«c rn
FIGURE 5. PERMEABILITY VS. DENSITY RELATIONSHIP
-------
implied that the soil would have a relatively low adsorption capacity for
organic contaminants. Therefore, contaminants could be expected to wash off
relatively easily, compared to a high TOC soil, e.g., 2-4 percent.
6.2 SURFACTANT SELECTION
The results of the water solubility tests of several surfactants and
surfactant combinations are presented in Table 10.
TABLE 10. SURFACTANT SOLUBILITIES IN WATER
SURFACTANTS
SOLUBILITY RESULTS
1% Richonate® YLA
4% Adsee® 799
2% Adsee® 799
2% Adsee® 799
3% PFC - 2639
0.5% ETGa
0.5% ETG +
0.5% ETG +
0.5% EPGb
0.5% EPG +
0.5% EPG +
2% Richonate® YLA
2% Hyonic® NP-90
1% Adsee® 799
1% Hyonic® NP-90
1.5% Active 8000
1.5% Nepco® 1186-A
1% Adsee® 799
1% Hyonic® NP-90
insoluble
soluble
soluble
soluble
soluble
insoluble
insoluble
insoluble
insoluble
insoluble
insoluble
soluble
insoluble
a Emulsan Technical Grade from Petroferm
b Emulsan Purified Grade from Petroferm
Manufacturers: Witco Chemical -- Adsee® 799, Richonate® YLA
Diamond Shamrock — Hyonic® NP-90, Nepco® 1186-A
Petroferm -- PFC-2639, Emulsan
Bull en Chemical Co./Midwest -- Active 8000
Richonate® YLA was not soluble in deionized water to the extent of 1 percent
unless mixed with another surfactant (Adsee® 799). A 4 percent combination of
Adsee® 799 and Hyonic® NP-90 was soluble. The Petroferm Emulsans, which are
1ipoheteropolysaccharide biopolymers produced by fermentation, were insoluble
even at 0.5 percent (weight/volume), even with 1 percent Adsee® 799 or 1
percent Hyonic® NP-90 added.
41
-------
The clay and oil dispersion test results, presented in Table 11, showed
excellent oil dispersion and minimal clay dispersion by a combination of
equal parts of Hyonic® NP-90 and Adsee® 799, which are both nonionic surfac-
tants used as wetting agents. Hyonic® NP-90 is a polyethoxylated nonyl
phenol, with an average of 9 ethoxyl groups in the polyethoxy side chain.
Adsee® 799 is a blend of polyethoxylated fatty acid esters. Both of the
surfactants have been shown in multiple test systems to be biodegradable.
The solubility, minimal clay dispersion, and excellent oil dispersion
characteristics of a 1:1 mixture of Adsee® 799 and Hyonic® NP-90 suggested
that this mixture would be effective for organics contaminated soil cleanup,
and deserved further testing.
6.3 PRELIMINARY SOIL COLUMN EXPERIMENTS
At the beginning of the study, the effect of soil washing with water,
followed by 4.0 percent surfactants (2 percent each of Adsee® 799 and
Hyonic® NP 90), and a final water rinse was investigated in soil column
experiments using the Murban distillation fraction, PCBs, and di-, tri-, and
pentachlorophenol contaminants. Separate samples of freehold soil were
spiked with 1,000 ppm Murban distillate cut, 100 ppm PCBs, and 30 ppm chlor-
inated phenols. In each case, nine columns were treated with a 10 pore
volume water wash, then a 10 pore volume 4.0 percent surfactant wash, and
then an additional 10 pore volume water rinse. The soil columns were sacri-
ficed serially for soil analysis, one after each 3 to 4 pore volumes (called
one pass). Duplicate leachate samples were collected and analyzed for the
pollutant group of interest at the time of each column sacrifice.
Results of these column experiments are presented in Figures 6 through 8
which show the relative contaminant concentration in the soil and leachate as
a function of the treatment stage. The effect of the various wash steps on
Murban contaminated soil is seen in Figure 6. The initial water wash had no
effect: less than <0.002 percent of the contaminant was detected in the
'leachate, even after ten pore volumes. However, upon initiation of surfactant
washing, 74.5 percent of the pollutants were removed in the leachate after
three pore volumes. Additional pore volumes of surfactant increased the amount
of Murban distillate cut removed to 85.9 percent after 10 pore volumes. The
pollutant concentration in the soil was reduced to 6.18 percent of the initial
spike value after the tenth pore volume of surfactant. The final water rinse
showed only minimal effects: after the tenth pore volume of water rinse, the
soil still contained about 7.0 percent of the initial spike whereas the total
amount of contaminant leached was 88 percent. (Note that since the soil and
leachate concentrations are based on several different columns treated in
parallel, some variability between results at different stages of each test
are unavoidable. This variability caused the apparent increase in soil levels
between the second pass (pore volumes 4-7) and third pass (pore volumes 8-1U)
of the water wash, and again between the last pass of surfactant washing, and
the subsequent water rinses.)
42
-------
TABLE 11. RESULTS OF SURFACTANT CLAY AND OIL DISPERSION TESTS
Extent of Clay Dispersion
Oil Dispersion Ability
Surlactamts)
Clearest
Internediate Cloudiest
Excellent
Good
Average
Poor
CO
Detoniied Uaier
41 Adsee' 799
IX Adsee' 799
IX Adsee:799 • IX NP-90
IX lichonate'fLA
IX Adsee 799 • tX *tchonale*UA
0.25X NP 90 • O.SX ftichonate^YLA
IX PfC-2619 • IX Adsee'-W
O.SX EPC (a) « 2X Adse#?7V9
)X PfC-2619
}X PfC-2619 • IX MP 90
O.SX EIG (b)
O.SX EIC • 2X A
O.SX EIC • 2X KP 90
0.5X EPC
O.SX EPC • 2X HP-90
1.SX Active 8000
I.SX Nepco 1186 A
X
X X
X X
X
X X
X X
X X
(a) Enulsan technical Grade from Petrofera
(b) Eiulsan Purified Grade tram Pelrofera
Manufacturer*: Uitco Chemical •• Adsee'^99. ftichonate**IA
OianoiiiJ Shamrock •• HP 90, Nepco&1ia6-A
fclrolcrm •• P»C-2619, Enulsan
Sullen Cheraical Co./Hiduest •• Active 8000
-------
100 '
3 go '
i
h-
c
II
£ 60 '
o
O
c
s
i
2 «o "
c
o
O
u
*" 20
< 001
I-J
'* ••,.,„
10 1
I
r oul
II 1
I
D =
t 0»
< 111
1
Su
Lf
il
sacliale
i
1
u i
1-J H-IO • I-J H-J
Vlll.HIK.-4 **"* I'OIC Vlllll
n »
1
1 11
a-io
1
II *
1 M
II •
1-3 1-1
Wdlei Him
1 •
Ps>,
L^
r>o.
II •
H-IO
I'lllC VulllllK.-! '
FIGURE 6. MURBAN SOIL COLUMN CLEANUP
WITH 2"L OF EACH SURFACTANT
-------
tn
m =
: • Suit
1 1 — Leal-hale
•i i
100 '
Relative Contaminant Concentration ( i)
„ * v a>
S 0 O 0
1 1 - 1 .
M •
I
uu«
- — 1 1
^0
I
\
I
010
1
I
1-1 H-l B-IO
Wjlci V/jili _,_
^ I'oic Vi.Uiinci '''
.
« » j
I
>* •
P7?
«> i
I I1"
tl t
1 HU
m
i
1 V>
P77
.11
1 3»
• • •
kt 1
•-« ,-i »-,„ i-. --I
Siufjcldiil Wd^l) WjU-i Unibi--
I'lll C VUIIIIIie& I'll! C V4HUIIU:^
FIGURE 7. PCB SOIL COLUMN CLEANUP
WITH 27o OF EACH SURFACTANT
-------
n
leachate
Hid
»' III! '
Concent rat ic"
c
c
i
3 -tn
o
c-l
a>
Sc 20 "
-
•a •<
•
- '..
'
x'
X
^
X
\
V
|2J So"
< .1 Ll.
H.J
<
.HI
rr
,-..«
»^r
».»
.
.1
k9.t
1
< 1
».t
^ .1
tt.9
1
<.,
v.s
i
< i
....
<
< i
i
,».»
I-J
4-7
(I-IU
1-3
4-7
U-IO
I-.1
4-7
11-10
(KllllllUlt
Uulci Wash
Tore Volumes
SurfacMiil Mash
Pore Volumes
Core Volumes
FIGURE 8. CHLORINATED PHENOL SOIL COLUMN CLEANUP
WITH 2% OF EACH SURFACTANT
-------
Similar cleanup behavior was observed for the column experiments using
PCB spiked soil. Figure 7 shows that the initial water wash was ineffective
in cleaning PCBs from the soil with only 0.015 percent being removed after
the tenth pore volume. As for the Murban distillate cut column test, the
soil was cleaned substantially by the 4.0 percent surfactant solution. In
this case, 60.8 percent of the PCBs was detected in the leachate after the
third pore volume with less than 10 percent remaining on the soil. After the
final tenth pore volume of water rinse, 68.2 percent of the PCBs was detected
in the leachate and only 1.38 percent was detectable on the soil.
Similar soil column experiments were also conducted using a 30 ppm chlo-
rophenols mixture and, in contrast to the PCB and Murban results, the bulk of
these contaminants was removed with the initial pass of water wash. Figure 8
shows that 64.5 percent of the chlorinated phenols was removed by the first
water wash, while only 2.1 percent was detected in the soil. After the third
pore volume of surfactant wash, no chlorinated phenols could be detected in
the soil while almost 70 percent was found in the aqueous leachate. The sur-
factant probably interfered with the extraction of the .PCBs and chlorinated
phenols when the leachate samples were extracted with methylene chloride.
Thus, a complete mass balance was not obtained in these early tests, and the
leachate plus soil values equal less than 100 percent.
For all contaminant groups investigated, soil washing methods were good,
as 68-88 percent of each contaminant mixture was ultimately removed from the
soil. The encouraging results obtained from these initial soil column studies
warranted further investigations into the feasibility of aqueous surfactant
soil washing. The same experimental design was used for further evaluations
to optimize surfactant concentrations and leachate treatments (as discussed
in the following sections).
6.4 OPTIMIZATION OF SURFACTANT CONCENTRATION
To optimize the cost-effectiveness of a soil washing counter-measure, it
was necessary to determine the minimum concentration of surfactant that would
yield acceptable soil cleanup. Surfactant concentrations were variecf from
0 to 1.0 percent of each individual surfactant in shaker table experiments
using both PCB and Murban contaminated soils. Then column experiments were
undertaken to verify the shaker table test data and also to narrow the range
of viable surfactant concentrations.
6.4.1 Shaker Table Tests
Using Freehold soil with a PCB spike of 100 ppm, a series of surfactant
concentrations was examined for soil cleaning potential. One hundred grams
of PCB spiked soil was agitated with 200 ml of surfactant solution for one
hour, then centrifuged, and the soil and leachate were analyzed for PCB
content. The surfactant concentrations tested in duplicate were: 0, 0.001,
0.01, 0.10, 0.25, 0.50, 0.75, and 1.0 percent of each of the two individual
surfactants in combination (0 to 2.0 percent total surfactant).
47
-------
Figure 9 shows the effect of varying surfactant concentrations on PCB
partitioning between soil and Teachate. There was essentially no cleanup of
the soil with surfactant concentrations of 0.25 percent (0.50 percent total)
or below. At a concentration of 0.50 percent there were noticeable amounts
of PCBs contained in the leachate; cleanup was further enhanced by increasing
the surfactant concentration to 0.75 percent. However, increasing the sur-
factant concentration to 1.0 percent did not further improve cleanup: similar
PCB partitioning was observed for 0.75 percent and 1.0 percent surfactant
concentrations.
102
U
w
e
41
-------
A similar shaker table experiment was conducted in duplicate, using the
Murban hydrocarbon pollutant at a spike level of 1,000 ppm. The same surfac-
tant concentrations were tested to determine if the optimum concentration was
contaminant dependent. Figure 10 presents the relative hydrocarbon content in
the leachate and soil for the various surfactant concentrations. Small but
measurable amounts of hydrocarbons—ranging from 1.48 to 2.49 ppm—were
detected in the leachate with surfactant concentrations of 0.001 percent to
0.25 percent. As with the PCB shaker table experiment, there was enhanced
cleanup beginning at 0.50 percent surfactant concentration, with 35.8 ppm
hydrocarbons detected in the leachate. Increasing the surfactant concentra-
tion to 0.75 percent further enhanced cleanup, with 47.6 ppm hydrocarbon
content in the leachate.
100
90
80
70
60
SO
40
30
20
10
91.3
92.1
86.5
2.0
1.6
88.9
• Soil
| [ » leachate-
1.2
52.2
!
28.4
42.0
37.8
32.5
26.3
I
.001
.01
.10 .25 " " .50
Surfactant Concentration (?)
1.0
FIGURE 10. MURBAN SHAKER TABLE
RECOVERIES VS. SURFACTANT CONCENTRATION
49
-------
Figures 9 and 10 show that the partitioning behavior (i.e., distribu-
tion between surfactant solution and the soil) for hydrocarbons and PCBs with
varying surfactant concentrations is somewhat similar. Individual surfactant
concentrations of 0.25 percent and below were ineffective; increased surfac-
tant concentrations caused increased soil cleanup from 0.50 percent to 0.75
percent surfactant; however, above 0.75 percent of each surfactant there was
little significant enhancement of soil cleanup.
6.4.2 Column Tests
To ensure that the optimum surfactant concentration under gravity flow
conditions was not significantly different from the optimum under equilibrium
conditions, column tests with various surfactant concentrations were run on
soil spiked with 100 ppm PCBs.
Columns were treated with one pass of 0.50, 0.75, and 1.0 percent of
each surfactant (1.0, 1.5, and 2.0 percent total surfactant), and the migra-
tion and mobilization of PCBs within the column was noted. Columns 1, 2, and
3 received one, two, and three pore volumes, respectively, of 0.50 percent
surfactant before sacrifice and soil analysis. Columns 4, 5, and 6 received
one, two, and three pore volumes, respectively, of 0.75 percent surfactant
before sacrifice! Likewise, columns 7, 8, and 9 received one, two, and three
pore volumes, respectively, of 1.0 percent surfactant before sacrifice.
Three columns of unspiked soil were used as controls, each one receiving
three pore volumes of 0.5 percent, 0.75 percent, or 1.0 percent of each test
surfactant.
No initial water washes or final water rinses were run through the
columns. The downward migration.of PCBs is apparent from the graphical
presentation of data in Figure 11, which presents the PCB concentrations in
the various portions of the columns as a function of pore volume for each of
the three surfactant concentrations tested. A comparison of PCB migration
rates indicates that PCB mobilization was greatest at 1.0 percent surfactant,
somewhat less at the 0.75 percent surfactant concentration, and much less at
0.50 percent surfactant. This fact can be observed most readily by noting
the differences between bottom soil PCB concentrations with the varying
surfactants. After the three pore volumes there was a PCB concentration at
the bottom of the column of 244 ug/g with the 0.50 percent surfactant,
compared to 405 ug/g when using 0.75 percent surfactant and 562 ug/g when
using the 1.0 percent surfactant. As Figure 11 indicates, there was a smaller
improvement in the PCB migration rates between 0.75 percent and 1.0 percent
surfactant concentrations than between 0.50 percent and 1.00 percent.
6.5 EVALUATION OF LEACHATE TREATMENT TECHNIQUES
Large amounts of surfactants and wash water are required for field
application of this countermeasure technology. Surfactants are expensive,
and for this technology to be cost-effective, surfactant recycling is an
important consideration. Accordingly, various leachate treatment techniques
were evaluated for their ability to remove and concentrate the contaminants
while leaving the surfactants behind for further use. All treatment methods
evaluated were ineffective in accomplishing this. It appears that the same
50
-------
620
580
540
500
460
400
360
320
§ 240
S 200
c
41
§ 160
u
120
' 80
40
Par*
Volun.
491
316
33.6
210
244
102
71
^
16.2
77.4
61.2
5.9
28.2
* 100
« Middle
» Bottom
562
405
116
233
^
* —
31.
7.06
332
Z18
78.9
184
>
1st
0.5
2nd
3rd
1st
2nd
0.75
3rd
7.50
—F1
2ii r
14.9
1st
2nd
- 1.0
Surfactant Concentration (*)
* Samples Lost
FIGURE 11. PCB SOIL COLUMN CLEANUP
VS. SURFACTANT CONCENTRATION
chemical and physical properties of the surfactant mixture used that act so
well to extract the pollutants from the soil also inhibit separation of the
contaminants from the surfactants.
As a second consideration, large volumes of contaminated leachate are
generated by cleaning soil with aqueous surfactants. Consequently, various
leachate treatment techniques were evaluated for their ability to (1) concen-
trate the contaminants to facilitate disposal, and (2) clean the water enough
that it could be sent to a POTW or reused.
51
-------
Experiments with various leachate treatment alternatives showed that
dilute alkaline hydrolysis of a surfactant in the leachate, followed by
neutralization, produced a clean aqueous effluent containing a fraction of a
percent of salts — the surfactant components separated from the leachate
solution and sank, taking the contaminants with them. Either activated carbon
or foam fractionation could be used to further purify the leachate following
hydrolysis, producing a very clean effluent. The experiments leading to these
results will be described in this subsection.
Evaluation of leachate treatment alternatives for the aqueous surfactant
countermeasure has included three phases:
o Examining potentially feasible leachate treatment methods
o Preliminary testing of the most feasible methods
o Adapting the best of the feasible methods for use with soil column
tests.
Seven techniques for leachate treatment were identified for initial
examination of potentially feasible alternatives:
o Foam fractionation
o Sorbent adsorption
o UUrafiltration
o Surfactant hydrolysis/Phase separation
o Flocculati on/Coagulati on/Sedimentati on
o Centrifugation
o Solvent extraction.
Foam fractionation, sorbent adsorption, and ultrafiltration, were
considered most likely to be feasible techniques for leachate treatment, so
they were subjected to preliminary laboratory tests using simulated leachate.
Surfactant hydrolysis was also tested; the idea was conceived by SAIC staff as
a novel method for leachate cleanup. The goal in leachate treatment was to
remove the contaminants from the leachate solution, and isolate them in a
concentrated form. Partial or complete recycle of the surfactants, because of
their high cost in field scale applications, was also a goal. This was not,
however, attained with any of the treatment methods.
The other three techniques initially considered, flocculation/coagula-
tion/sedimentation, centn'fugation, and solvent extraction, were considered to
be much less feasible, for reasons explained in Section 6.5.2, Less Feasible
Treatment Alternatives.
6.5.1 Laboratory Tests of the Most Feasible Treatment Alternatives
Preliminary laboratory tests of foam fractionation, sorbent adsorption,
hydrolysis, and ultrafiltration were conducted to assess the feasibility of
these methods for removing the contaminants from leachate following surfactant
washing of soils. All of these methods were effective for removal of contam-
inants in the preliminary tests, described below. Ultrafiltration was the
52
-------
only method not further developed through tests with actual column leachate;
time and budget limitations precluded further work. The only treatment method
that effectively removed contaminants from the raw leachate was hydrolysis,
which destroyed one of the surfactants in the leachate and made it impractical
to recycle the other.
6.5.1.1 Foam Fractionation
Foam fractionation is one of several separation methods which involves
the selective adsorption of surface-active solutes (surfactants) at the
gas-liquid interfaces of bubbles rising through a liquid column. As gas is
bubbled through a solution containing a surfactant, a surfactant-rich foam
forms at the top of the column. Removal of the foam as.it forms results in a
gradual reduction of surfactant concentration in the liquid column, and simul-
taneous removal of any liquid or solid contaminants suspended in the liquid.
Foam separation techniques are ideally suited to removing the surfac-
tants and associated contaminants from the collected leachate. The removal
efficiency of the technique is mostly dependent on three variables:
o Bubble size
o Gas flow rates
o Surfactant concentration.
The experimental system to test foam fractionation techniques was
initially a single fractionation column using a batch process. The column
design is depicted in Figure 12. Diffusers which produced a range of bubble
sizes were employed, because" in most of the published studies reviewed, bubble
size was not tightly controlled.
The results of the batch foam fractionation tests, presented in Table 12,
show that good clean up of the leachate was achieved if the concentration of
surfactant was below about 0.1 percent, while no significant reduction in
surfactant occurred if the starting concentration was above that.
For example, in Run #3, the surfactant concentration in the model
leachate was decreased from a starting concentration of 0.013 percent to only
0.003 percent in the final residue, a decrease of 77 percent. The volume of
the starting leachate decreased by only 13 percent (from 485 ml to 420 ml in
the residue), the balance becoming foamate, the liquid which condenses from
the surfactant-laden foam. The net effect, 77 percent of the surfactant
becoming concentrated in only 13 percent of the liquid volume reflects a
substantial reduction in volume of leachate. This could be improved through
further foam fractionation steps. However, starting with surfactant levels of
0.045 percent (Run #5), the foamate contained 87 percent of the surfactant,
but was also 54 percent of the liquid volume. At 0.128 percent starting
surfactant, using a continuous flow mode of fractionation, the performance was
even worse: the level of surfactant after 108 minutes of foam fractionation
decreased by only 5 percent (from 0.128 percent to 0.122 percent).
The foam fractionation system was upgraded to a multistep continuous
process for testing the cleanup efficiency for leachate solutions using a more
53
-------
.n
*
Broken Foam In
*
Air [n
-------
TABLE 12. SINGLE COLUMN FOAM FRACTIONATION CLEANUP RESULTS
Run t
2
It
ft
3
It
It
4
ii
it
5
It
ft
7
n
it
8
It
It
It
9
it
it
it
M
»
H
It
It
Sample
Starting Surfactant
Time Final Residue
Foamate
Starting Surfactant
Time Final Residue
Foamate
Starting Surfactant
Time Final Residue
Foamate
Starting Surfactant
Time Final Residue
Foamate
Starting Surfactant
Time Final Residue
Foamate
»
Starting Surfactant
Residue SI
Time Final Residue
Foamate
Starting Surfactant
Residue @ 42 min.
Foamate @ 42 min.
Residue @ 61.5 min.
Foamate @ 61.5 min.
Residue 9 83.3 min.
Foamate @ 83.3 min.
Residue @ 108 min.
Foamate @ 108 min.
Concentration (J)
.013
.003
.064
.013
.003
.064 (
.032
.003
.041
.045
.006
.056
.390
.336
.678
.133
.134
.133
.144
.128
.124
.134
.110
.126
.119
.132
.122
.312
Volume (ml )
500
310
_a
485
420
-
480
335
-
490
225
-
360
255
-
360
-
-
-
Continuous Flow
ti
n
it
it
it
n
it
it
a - Foamate volumes can be calculated by difference, continuous flow volumes can be
obtained bj rates
55
-------
efficient design. Dual column, multiple pass foam fractionation was tested
for treating 1.5 percent surfactant solutions with and without 2.0 percent
calcium chloride (added to promote phase separation following hydrolysis).
The results were consistent with the results of the batch foam fractionation
tests. The high concentration of surfactant found in the raw column leachate
could not be reduced using foam fractionation, even with an ionic species
added to the solution to promote separation. The foamates showed no increase
in surfactant concentration over the residue. Even if the leachate removed
through extraction wells in field tests of the surfactant counter-measure
would be diluted two- to threefold by groundwater, this leachate would still'
be too concentrated for treatment by foam fractionation.
Foam fractionation was further tested for polishing low surfactant level
solutions after preliminary treatment by other methods. (See Subsection
6.5.1.3, Surfactant Hydrolysis and Phase Separation.)
6.5.1.2 Sorbent Adsorption
Eleven solid sorbents were screened to determine their efficiency in
removing PCBs and,the surfactants from an aqueous solution. The sorbents were
tested by adding one gram of each sorbent to 50 ml of model leachate contain-
ing 1.5 percent total surfactant and 1.10 mg of PCB, swirling for 5 minutes
and letting stand for 10 minutes. The sorbents tested and their performance
in this experiment are summarized in Table 13. None of the sorbents was very
efficient in removing PCBs from a surfactant solution. A removal efficiency
of about Ig per gram of sorbent represents good sorption efficiency.
The most efficient sorbent for PCB removal was the Filtrol XJ-8401, with
an efficiency of 0.00045 g/g, followed by WV-B 14x35, WV-G 12x40, and WV-L Rx30
Activated Carbons, and Celkate magnesium silicate. The surfactants are
apparently as effective in removing PCBs from, or preventing their adsorption
to, sorbent materials as in removing PCBs from soil.
For selective removal of PCBs from solution in preference to the
surfactant, the WV-B 14x35 Activated Carbon was best, with 19 percent PCR
removal compared with 11 percent removal of the surfactants. Thus, even
though the overall adsorption efficiency of the sorbents in the presence of
surfactants is low, small amounts of very hydrophobic compounds could be
removed if a sufficiently large proportion of sorbent were used. For
relatively toxic materials like PCBs, this may be practical.
6.5.1.3 Surfactant Hydrolysis and Phase Separation
Hydrolysis treatment of the surfactant and contaminant containing
leachate was tested to find if the Adsee® 799, a fatty acid ester, would
form a separate organic phase upon hydrolysis which contained both the sur-
factants and the organic contaminants. The first tests of hydrolysis for
leachate treatment involved boiling the solution with approximately one
equivalent of acid for 0.5 hr, followed by neutralization with a base, addi-
tion of salt, and cooling to allow separation of the organic .phase. Salt
was also added to the hydrolysis mixture to promote separation of the organic
56
-------
TABLE 13. SORBENT BATCH TEST RESULTS
Removal Efficiency3
(grams adsorbed/grams sorbenc)
Sorbenc Name
Filtrol Grade XJ-8308 (clay pellets)
Fllcrol Grade XJ-8401 (clay pellecs)
QS-13683 (clay pellets)
Airfloated Bond Filter (clay pellets)
Sorbo Gel (Cellte diatomite)
Celkate (magnesium silicate)
WV 3-14x35 (granular activated carbon)
WVG-l2x40 (granular activated carbon)
WVL-8x30 (granular activated carbon)
WVW-12x40 (granular activated carbon)
Oil Loc (expanded basalt)
Control (no sorbent)
PCB
.00011
.00045
.0002
.00016
.00021
.00028
.00032
.00028
.00028
.0002
0.0
0.0
Surfactant
.150
(b)
.180
.090
.090
.195
.083
.195
.150
.105
.120
0.0
a - One gram of each sorbent was added to 50 ml of leachate containing 1.57.
surfactant and 1.10 mg of PCB, swirled for 5 minutes, then let stand
for 10 minutes.
b - Sample lost
57
-------
phase from the aqueous phase. The reuse of the aqueous salt solution from
treatment of the contaminated leachate for treatment of another sample of
contaminated soil, by dissolving additional fresh surfactants, was tested in a
shaker table experiment. Because of the high (8 percent) content of salt in
the water solution following hydrolysis, the PCB removal with the recycled
solution was only 34 percent as efficient as removal with new surfactant
solution. The salt content was mainly the calcium chloride which was added
to the leachate solution to promote phase separation following hydrolysis
(see Table 14); acid neutralization also produced a salt.
In later tests of hydrolysis treatment, hydrolysis with a strong base
such as sodium hydroxide was found to promote better separation of the organic
phase than acid-catalyzed hydrolysis, so alkaline conditions were used for all
subsequent hydrolyses.
Although foam fractionation and sorbent adsorption could be used as
polishing methods for remov.ing traces of contaminant and surfactant from
leachate solutions, only hydrolysis with a strong base was found to be an
effective initial treatment for the higher surfactant concentrations found in
the raw leachate. To reduce the volume of aqueous salt solution generated by
leachate treatment, thereby allowing the water to be recycled and minimizing
the cost of disposal during field implementation, treatment procedure modifi-
cations were tested.
TABLE 14. BASE HYDROLYSIS TREATMENT OF LEACHATE
Sample Description
Concentration (mg/l) Volume (ml ) Tocal Mass (siq)
- Surfactant PCB's Surfactant
PCH-l Starting Leachate
PCH-2 Aqueous Phase After
Hydrolysis (w/CaC!2)
PCH-3 Oil Phase After
Hydrolysis (w/CaCl2>
PCH-4 Aqueous Phase After
Hydrolysis (no CaCl2)
PCH-5 Oil Phase After
Hydrolysis (no CaCl2)
19.8 15,000
.137 24
205
(a)
2.10
155
250 4.95 3750
330 O.U452 7.9
16.3 3.34
234 0.491
59.0 9.l5b
a - Not analyzed
b - Suspect non-homogeneous sample
58
-------
A synthetic PCB leachate was treated by hydrolysis without adding salt;
only the 0.1 percent of salt from base neutralization was left in the solu-
tion. Alkaline hydrolysis of 6 1 of this leachate, containing 16 ppm of
PCBs in 1.44 percent aqueous surfactants, followed by neutralization, yielded
6.9 1 of treated aqueous solution with only 0.017 percent of surfactants
remaining; a small (0.09 1) separate layer of surfactant hydrolysis products
containing 95.4 percent of the PCBs (1100 ppm PCBs) also formed.
Further treatment of the aqueous surfactant solution with a column of
activated carbon (WVB 14x35) yielded a solution containing only 0.01 ppm of
PCBs.
Following hydrolysis, the treatment of the aqueous effluent by foam
fractionation was also shown to remove the residual surfactants from the
leachate. A four-column series of foam fractionation columns operating in a
continuous counter-current flow mode was used (see Figure 13). The test
results demonstrating this are summarized in Table 15. Both the final salt
level (1800 ppm) and the residual PCB level (0.0036 ppm) should be low enough
to allow disposal to a publicly owned treatment works, and were low enough to
permit reuse of the leachate water for soil cleaning.
The cleanup of a soil column spiked with PCBs, by recycling the treated
leachate water for successive passes of aqueous surfactants through the
column, was as effective as with fresh surfactant solution (see Section 6.6,
Evaluation of Leachate Recycling). The recycled leachate was treated by
alkaline hydrolysis/phase separation, with polishing by granular activated
carbon. The final PCB level in the treated leachate was only 0.57 ppb.
6.5.1.4 Ultrafiltration
*
Ultrafiltration is a hydraulically driven separation technique that
employs a thin (0.1 - 0.5 micron) semipermeable membrane integrally bonded to
a highly porous polymeric substrate for filtering very fine particles from a
suspension under pressure. The Millipore Pell icon Cassette system, which was
used for testing, utilizes a transverse-flow geometry to continually sweep
the membrane clear. For our tests we used a 460 cm^ (0.5 ft^) Millipore PT
series membrane with a pore size equivalent to a molecular weight cutoff of
10,000. The PT series membrane consists of polysulfone on a polyethylene
support.
Testing was conducted on two leachate types; the first consisted of
approximately two liters of an aqueous phase after hydrolysis, containing
0.546 percent surfactant, to which was added 20 mis of saturated polyvinyl
alcohol (PVA) in water. PVA is a safe, inexpensive, water-soluble polymer,
with an average molecular weight of 40,000. The addition of PVA was thought
to be a way to promote a polymer-surfactant complex that would stabilize
large surfactant micelles, thus allowing efficient filtration. The second
test was conducted on straight 3.3 percent (total) surfactants without any
complexing agent. Test results are presented in Table 16.
The first 100 ml of filtrate was discarded, then an aliquot was collect-
ed and its surfactant concentration was determined to be 0.01)26 percent. A
. 59
-------
CD
O
Foam Breakers
Concentrated
foam
Kir In
Spray
UdtLT
Oul
FIGURE 11. COUNTERCURRENT FOAM FRACTIONATION SCHEME
-------
composite and, therefore, more representative sample was obtained after
540 ml of filtrate had been collected and it showed a concentration of 0.025
percent while the remaining retentate had concentrated to 0.696 percent.
The system was allowed to flush with DI water before the second test was
conducted. After discarding the first 100 ml of filtrate, 150 ml of filtrate
was collected. The filtrate sample was analyzed and its surfactant concen-
tration was 0.27 percent, while the retentate had concentrated to 3.79
percent.
It should be noted that time did not allow for running the tests to
completion, which might have resulted in a tenfold reduction in the retentate
volume. The results presented here represent approximately 40 minutes of
filtering time per-test.
TABLE 15. HYDROLYSIS AND FOAM FRACTIONATION TREATMENT OF LEACHATE
PCB's
Surfactant
Salt
Concentration Changes
in a Treated Aliquot
Volume
Starting Simulated
Leachate
Aqueous Phase After
Hydrolysis
Oil Phase After
Hydrolysis
105 mg
0.47 mg
142 mg
110 g 0 g 8000 ml
2.47 g- 8. 2 g 6970 ml
n.a. a. a. 120 ml
Starting Simulated
Leachate
Aqueous Phase After
Hydrolysis
Oil Phase After
Hydrolysis
Aqueous Phase After
Foam Fractlonation
Foamate Phase
13
•0
1180
0
0
.1 ppm 13,800. ppm
.067 ppm 354. ppm
. ppm n.a.*
.0036 ppm 209. ppm
.100 ppm 1280 ppm
0 ppm 6190
1200 ppm' 5390
n.a.* 92
n.a.* 5030
n.a.* 360
ml
ml
.7 ml
ml
ml
*not analyzed
61
-------
6.5.2 Less Feasible Treatment Alternatives
Three techniques initially considered feasible for leachate treatment
were not tested in the laboratory because other methods seemed more promising
for efficient cleanup, and because of budget limitations for the project. The
reasons for considering these techniques less feasible than the ones tested
are presented in the next three subsections.
TABLE 16. ULTRAFILTRATION TEST RESULTS
Test #
Sample
Volume (ml) Concentration (%)
1
1
1
1
1
2
2
2
2
Initial leachate before PVA
Initial leachate with PVA added
First filtrate
Composite filtrate
Retentate
Initial leachate
First filtrate
Composite filtrate
Retentate
1950
1960
540
1420
1350
150
1200
0.546
0.531
0.0026
0.025
0.696
3.30
0.144
0.270
3.79
6.5.2.1 Flocculat ion/Coagulation/Sedimentat ion
The addition of materials to the leachate solution to encourage the
formation of settleable floes appears to have little potential for leachate
cleanup. The formation of floes requires that the suspended material to be
removed have a surface charge, which results mainly from the presence of ions,
leading to coagulation of the suspended particles in the presence of appro-
priate polyvalent ionic flocculation materials.
Removal of suspended solids from the leachate, especially soil particles,
occurs as it moves through the soil column and as it exits the column through
a glass wool filter. Fines are also removed through settling in the leachate
62
-------
receiving vessel. However, removal of the very fine surfactant-contaminant
droplets (micelles) requires more stringent methods. The micelles will not
have full ionic charges,at their surface, and the charges at their surface
due to polarization and electron delocalization within the surfactant mole-
cules are not likely to be strong enough to produce efficient floccing.
Sweep floccing, in which very large amounts of flocculant literally sweep
the particles out of suspension was considered possibly feasible, but not
practical.
6.5.2.2 Centrifugation
The settling of contaminant-surfactant particles suspended in the
leachate solution might be accelerated by centrifugation if the particles were
denser than the solution. In the case of PCB cleanup, this would occur; but
in the more general case in which the bulk of the contamination is hydro-
carbons, the suspended particles will probably be less dense than the aqueous
solution. Centrifugation would not be very effective in that case.
6.5.2.3 Solvent Extraction
Solvent extraction of the organic contaminants from the aqueous leachate
appeared infeasible because whenever solvent extractions of the solution were
performed in the laboratory during work-up for analysis, inseparable emulsions
formed. These emulsions broke very slowly, preventing phase separations for
hours. Furthermore, the extraction of low concentrations of organics from an
aqueous solution using an organic solvent can be expected to contaminate the
solution with the extraction solvent at a level significantly higher than the
level of the organic contaminants being removed.
*
6.6 EVALUATION OF LEACHATE RECYCLING
6.6.1 Column Tests With Untreated Leachate
To evaluate the effect of recycling the aqueous leachate on soil cleanup
a PCB soil column experiment was conducted. Eight columns were packed, as
before, with Freehold soil spiked with 100 ppm PCB. Two control columns were
packed identically, but with no PCB spike.
For comparison purposes, four columns received one, two, three, and four
passes (three, six, nine, or twelve pore volumes) (three pore volumes equals
one pass) of fresh 0.75 percent surfactant before being sacrificed, while four
other columns received similar amounts of recycled untreated surfactant solu-
tion before sacrifice. Recycling of raw leachate was accomplished by reintro-
ducing it to the top of the column. Three pore volumes of surfactant solution
(6 1) was used four times.
63
-------
The data from the raw leachate recycling column experiment are presented
graphically in Figures 14 and 15. Figure 14 compares the soil PCS concen-
trations in the fresh surfactant solution and the recycled (raw) leachates.
Figure 14A shows that fresh surfactant solution cleaned the top third of the
column first, and then the middle, followed by the bottom. In Figure 14B,
the effect of recycling leachate on the top portion of the column is shown.
It never gets as clean as when using fresh surfactant, and actual concentra-
tions increase from 5.71 ug/g PCB after the third pass to 34.1 ug/g PCB after
the fourth pass. Also, Figure 15 shows that after the third pass with fresh
surfactant, a "plug" of PCBs (182 mg) eluted off the column. This never
occurred with recycling—probably because of repartitioning of the PCBs onto
the previously cleaned top fraction of soil. Good cleanup of all portions of
the column was achieved after four passes of fresh surfactant; however,
recycling treatment at the same stage showed only limited cleanup at best.
Figure 15 presents a comparison of the total relative PCB concentration in
the whole soil versus the leachate for both fresh and recycled surfactant.
Only 6.9 percent of the PCBs remained on the soil after four passes of fresh
surfactant, while 43.4 percent of the PCBs remained on the soil after four
passes with leachate recycling.
6.6.2 Column Tests With Treated Leachate
Because recycling untreated leachate proved to be unacceptable, a column
experiment was devised in which the recycled leachate received treatment
between each pass. Four PCB spiked columns and one unspiked control column
were packed as before.
Four passes of surfactant solution were put through the columns, with
leachate recycling after each pass. The aqueous'leachate was treated by
^hydrolysis, followed by adsorption by activated carbon, remade back up to
1.5 percent total surfactant and allowed to pass through the column again.
The leachate was analyzed for PCB content before hydrolysis, after hydrolysis,
and after activated carbon treatment. The oil phase, which is the product of
hydrolysis, was also analyzed for PCB content. After each pass one of the
columns was sacrificed and the top, middle, and bottom sections were also
analyzed for PCBs.
The result of leachate hydrolysis was a relatively small volume of a
waxy, oil phase. Because of their hydrophobic nature, the contaminants
present in the leachate tended to preferentially partition out of the aqueous
leachate and into this oil phase. In other words, the aqueous surfactant
solution passed through the contaminated soil column and extracted the
contaminants, resulting in a large volume of uniformly contaminated surfactant
mixture. Upon hydrolysis, the surfactants separated out as an oil phase and
carried the contaminants with them. This resulted in a relatively clean
volume of water and a highly contaminated, much smaller volume of waxy oil
phase.
After hydrolysis, the oil and water phases were separated and the water
was further treated by passage through columns of activated carbon. Chroma-
tograms of extracts of leachate after secondary treatment with activated
64
-------
140
120 .
100 .
GO
CT
~ 60 .
e
1 *° '
s
^ = Too
IJI = Middle
r~j = Sotton
A. With Fresh Surfactant Solution
5.2.3
9.75
l^^
13.2
i.<525;3 I
7T&&
1st Pass
2nd Pass
3rd Pass
4th Pass
= .op
= Middle
1 _ |=
Bottom
B. With Raw I -achate
1st Pass
2nd Pass
3rd Pass
4th Pass
FIGURE 14. RAW LEACHATE RECYCLING:
PCB COLUMN SOIL LEVELS
65
-------
100
90
80
70
H 60
£ 50
30
20
10
72.4
80.3
I
Leachate
A. With Fresh Surfactant Solution
33.0
1st Pass
2nd Pass
3rd Pass
4th Pass
65.2
n
= Soil
= Leachate
1st Pass
2nd Pass
3rd Pass
B. With Raw Leachata
4th Pass
FIGURE 15. RAW LEACHATE RECYCLING:
SOIL AND LEACHATE RESULTS
66
-------
carbon showed detectable amounts of PCBs even after the third pass; however,
after the fourth and final pass there were no PCBs present in the leachate.
After leachate treatment, the surfactant concentration was measured and,
in most cases, found to be less than 0.01 percent. Therefore, between each
pass fresh surfactant was added to the treated leachate prior to recycling,
and the soil in the column received four passes of fresh surfactant. Only
the water was recycled.
Soil cleanup was successful. Figure 16 shows the PCB concentration for
the top, middle, and bottom portions of the column. The PCBs tended to
accumulate toward the bottom of the column before elution from the column.
After the fourth pass, only 6.17 mg of PCBs remained on the column (down from
an initial spike of 697.5 mg per column). This represents less than one
percent of the original soil contamination. Figure 17 shows the partitioning
behavior of PCB between soil and leachate as a function of the number of
passes delivered.
TABLE 17. PCB LEVELS IN HYDROLYSIS AND
SORBENT TREATED LEACHATE
Cumulative mg
removed from soil
Cumulative %a
removed from soil
PCB Content (total mg)
First Pass
Second Pass Third Pass
Fourth Pass
Before Hydrolysis
After Hydrolysis
After Activated
Carbon
653 + 113
1.21 + .57
.115 + .021
106 + 3.0
.448 -i- .306
.0697 + .0423
16.8 + .8
.539 + .221
.0488 + .0173
6.32
.0839
.00285
653
93.6
759
108.8
776
111.3
782
112.1
a - based on an initial spike of 697.5 mg/column
Results of duplicate leachate analysis are presented in Table 17, which
shows how effective the treatment method was. After the first pass, the
leachate contained 653 mg of PCB before treatment. After hydrolysis, the PCB
content was reduced to 1.21 mg and, following secondary treatment (by activated
carbon), the PCB concentration was further reduced to 0.115 mg. As the soil
67
-------
28
26
24 .
22 .
20
18
^16
3
c 14
o L*
» *
**
s-
g 12
u
c
o
s I0
Q.
.
6
» 4
4
2
5
. 2
•
10.5
HR(
.28
jrr
1
1
*
g
»
1
1
1
i
KS
25sS
f^J^U
fe
7.2
I^BOM
-
^ * TOP
5&S = MIDDLE
1 1 = BOTTOM
•
9,83
—
3.27
1.94
^
1
2'48 1.41
994^1 1 -747
' , *j5> .495 I I
;^«i c^d5S 1
1st Pass 2nd Pass 3rd Pass 4th Pass
FIGURE 16. TREATED LEACHATE RECYCLING:
PCS COLUMN SOIL LEVELS
68
-------
= Leachate
= Soil
112
1 IV
100 .
90 .
S 30 .
c
o
'5 70 .
w
*J
e
0)
2 60 .
o
5 40 .
eu
cc
30 .
20 .
10 .
33.6
14.3
1
"
.
4 \J J
5.02
^
-
111
1.72
S/S71
*
.38
1st Pass
2nd Pass
3rd Pass
4th Pass
FIGURE 17. TREATED LEACHATE RECYCLING:
SOIL AND LEACHATE LEVELS
69
-------
column was cleaned of PCBs with each pass, the contaminant concentration in
the leachate was also reduced, as shown in the table. With reduced PCS
content in the leachate, treatment became more effective, as indicated by the
PCB content in the leachate after the fourth pass. After the fourth pass,
only 6.32 mg was present in the untreated leachate; primary treatment removed
all but 0.0839 mg and this value was reduced to 0.00285 mg by treatment with
activated carbon. Used repeatedly, and initially contaminated with up to 131
ppm (653 mg/5.0 1) PCB, the contamination in the leachate was ultimately
reduced to 0.00057 ppm (0.00285 mg/5.0 1), of PCBs.
The ultimate fate and mass balance of the PCB contamination is summarized
in Table 18, where the PCB mass and volume or weight of the matrix is delin-
eated for the initial conditions, each pass, and the final conditions. The
initial conditions show that 697.5 mg PCB are contained in 6,975 grams of
soil, which is the 100 ppm soil spike. The final conditions show that only
6.17 mg of PCBs remained on the 6,975 grams of soil, only 0.00285 mg was
present in the 5.03 1 of treated water, while 641 mg of the PCBs was contained
in only 609 grams of oil phase material.
70
-------
TABLE 18. PCB MASS BALANCE FOR HYDROLYSIS AND SORBENT TREATED LEACHATE
(
INITIAL CONDITIONS
First Pass
Second Pass
Third Pass
Fourth Pass
FINAL CONDITIONS
Mass Balance : 641 *
Oil
512mg
82.4mg
39.ftng
6.5Qng
641/ng
6.17 t 2.28* .
Phase
^^
in 114g
1
in 118g
1
in 200g
1
in 14Sg
1
in 609g
Soil Phase
697. 5mg in 6,97Sg
99. Stag in 6.976g
1
36.Qng in 6.975g
1
12.Qng in 6.9/Sg
1
6.17mg in 6.975g
1
6.17mg in 6.97Sg
00285 = 649. Sing 93.
Treated Water
. 1 1 5 mg in 4
1
.0697mg in 4
I
.0488119 in 5
1
.0028 ing in 5
1
.OU28frng in 5
1%
Phase
70 i
93 i
n i
.03H
.03(1
* Sum of PCti mg before activated carbon
-------
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Myers, T.E., N.R. Francinogues, D.W. Thompson, and P.G. Malone. 1980,
Chemically Stabilized Industrial Wastes in a Sanitary Landfill
Environment. Disposal of Hazardous Waste: Proceedings of the Sixth
Annual Research Symposium. EPA-600/9-80-010, U.S. Environmental
Protection Agency, Cincinnati, OH. 291 pp.
Neely, N.D., Gillespie, F. Schauf, and J. Walsh. 1981. Remedial Actions at
Hazardous Waste Sites - Surveys and Case Studies. EPA-430/9-81-05
SW-910.
Payne, J.R., P.J. Mankiewicz, J.E Nemmers, et al. 1978. High Molecular
Weight Petroleum Hydrocarbon Analytical Procedures. Southern California
Baseline Study Year II Final Report III (5.0). Submitted to Mineral
Management Services.
Payne, J.R., .J.E. Nemmers, R.E. Jordan, et al. 1979. Measurement of Petroleum
Hydrocarbon Burdens in Marine Sediments by Three Commonly Accepted
Procedures: Results of a NOAA Inter-Laboratory Calibration Exercise;
Jan. 1979. 34 pp. plus appendix. Submitted to Dr. J. Calder, Staff
Chemist, OCSEAP, National Oceanographic and Atmospheric Administration,
Environmental Research Laboratory, Boulder, CO.
Phung, H., D.E. Ross, P.S. Pagoria, and S.P. Shelton. 1982. Landfilling of
Sludges Containing Metal Hydroxides, pp. 212-223 in Land Disposal of
Hazardous Waste: Proceedings of the Eighth Annual Research Symposium.
EPA-600/9-82-002, U.S. Environmental Protection Agency. 549 pp.
74
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REFERENCES (continued)
Pohland, F.G., J.P. Gould, R.E. Ramsey, and D.C. Walters. 1982. The Behavior
of Heavy Metals During Landfill Disposal of Hazardous Wastes, pp. 360-371
in Land Disposal of Hazardous Waste: Proceedings of the Eighth Annual
Research Symposium. EPA-600/9-82-002, U.S. Environmental Protection
Agency. 549 pp.
Pohland, F.G., J.P. Gould, R.E. Ramsey, B.J. Spiller, and W.R. Esteves. 1981.
Containment of Heavy Metals in Landfills with Leachate Recycle, pp.
179-184 in Land Disposal of Municipal Solid Waste: Proceedings of the
Seventh Annual Research Symposium. EPA-600/9-81-002a. U.S.
Environmental Protection Agency. 244 pp.
Pytlewski, L.L., K. Krevitz, A.B. Smith, E.J. Thorne, and F.J. laconianni.
March 1980. The Reaction of PCB's with Sodium, Oxygen and Polyethylene
Glycols, pp. 72-76 in Treatment of Hazardous Wastes: Proceedings of the
Sixth Annual Research Symposium. EPA-600/9-80-011, U.S. Environmental
Protection Agency. 173 pp.
Raamot Associates. 1983. Report of Permeability Evaluation Clarksburg Pit
for Chemical Additive Treatment Tank, U.S. EPA Tinton Falls, New Jersey.
Report submitted by Raamot Associates, P.A. to Mason & Hanger - Silas
Mason Company, Inc., P.O. Box 117, Leonardo, NJ.
Rollinger, G. (Rexnord, Inc.). 1978. Operations and Maintenance Manual:
In Situ Containment/Treatment Equipment. Report to HWERL-Cinn. Contract
"65-^2508.
Soil Survey Staff. 1975. Soil Taxonomy. U.S. Department of Agriculture,
Soil Conservation Service.Agriculture Handbook No. 436. Washington,
DC. 754 pp.
Texas Research Institute. 1979. Underground Movement of Gasoline on
Groundwater and Enhanced Recovery by Surfactants. Submitted to the
American Petroleum Institute, September 1979.
Texas Research Institute. 1982a. Enhancing the Microbial Degradation of
Underground Gasoline by Increasing Available Oxygen. Final Report to
the American Petroleum Institute, February 1982.
Texas Research Institute. 1982b. Test Results of Surfactant Enhanced
Gasoline Recovery in Large-Scale Model Aquifer. Submitted to the
American Petroleum Institute, April 1982.
Tinsley, I.J. 1980. Chemical Concepts in Pollutant Behavior. Wiley-- .
Interscience, John Wiley and Sons. NY.
USEPA. June 1979. Environmental Pollution Control Alternatives: Economics
of Wastewater Treatment Alternatives for the Electroplating Industry.
IERL EPA 625/5-79-016. 72 pp.
75
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REFERENCES (continued)
U.S. Environmental Protection Agency. 1984a. Review of In-Pi ace Treatment
Techniques for Contaminated Soils. EPA-540/2-84-003a. Cincinnati,
Ohio.163 pp.
U.S. Environmental Protection Agency. 1984b. Case Studies 1-23: Remedial
Response at Hazardous Waste Sites. EPA-540/2-84-002b. Washington, O.C.
873 pp.
Winn, B.M., and J.H. Schulte. April 1982. Containment and Cleanup of a
Phenol Tank Can Spill, May-June 1978, Charleston, SC, pp. 11-14 in
1982 Hazardous Material Spills Conference, Government Institutes.
76
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APPENDIX A
SHAKER TABLE EXTRACTION PROCEDURE
o A 150-200 gram aliquot of soil was transferred to a clean, tared
Teflon jar and the sample weight was accurately determined
o A 25-50 gram aliquot of soil was transferred to a tared aluminum cup
and placed in a 105C oven for dry weight analysis
o The soil sample was initially extracted with 200 ml of methanol for a
2-hour drying period
o The jar was centrifuged at 2500 RPM for 15 minutes and the methanol
extract removed and set aside for future use
o 200 ml of 35:65 methanol/methylene chloride solution was then added to
the extraction vessel and the sample was agitated for a 12-hour period
o The jar was centrifuged at 2500 RPM for 15 minutes and the methylene
chloride extract was removed; all three filtered extracts were
transferred to a separatory funnel
o 500 ml of 3% sodium chloride organic-free water was added to the
separatory funnel, and the organics were repartitioned by shaking the
separatory funnel
o At this point, the phases were separated by draining the methylene
chloride phase through a sodium sulfate drying column (25 grams) into
a Kuderna-Danish (K-D) flask
o The methanol/water phase was extracted 3 times with 50 ml of methylene
chloride and the combined methylene chloride extracts were passed
through the sodium sulfate drying column, into the K-D flask; another
300 ml of methylene chloride was then passed through the drying
column.
77
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APPENDIX B
GAS CHROMATOGRAPHY RUN CONDITIONS AND RUN PROGRAMS
Conditions for Gas Chromatographic Analysis:
Column: SE54-30N 30 meter fused silica capillary
Column pressure: 10 to 15 psi using He as the capillary inlet
carrier gas (flow rate 1.5 ml/min)
Injection: 1 ul splitless, using auto-injection sampler
Split vent: 30-40 ml/min
Septum purge: 1-1.5 ml/min
ECD makeup gas: argon/10% methane @ 30-40 ml/min
FID makeup gas: hydrogen @ 30-40 ml/min; air at 260 ml/min; nitrogen
at -30-40 ml/min.
Integration parameters:' zero @ 20% full scale deflection; slope
sensitivity @ 0.30; integrator area reject
(3 1,000,000,000 area counts
Run Program for a Murban Distillation Fraction:
Time (minutes) Action
0 Oven temperature at 45C
0.75 Inlet purge (backflush) begins
3 Integrator Area Reject reset to 100 area
counts (i.e., solvent peak has eluted)
5 Oven temperature assumes rate of 3.5C/minute
78
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Time (minutes) Action
72 Oven temperature reaches 280C and
stabilizes
80 Stop run
Retention times: Hexamethylbenzene (internal standard) elutes at 28 min,
n-decylcyclohexane (internal standard) elutes at 36 min.
Run Program for a PCB Extract:
Time (minutes) Action •
0 Oven temperature at 50C
0.75 Inlet purge (backflush) begins
3 Integrator area reject reset to 100 area
counts (i.e., solvent peak has eluted)
3 Oven assumes a rate of 5C/minute
25 Oven assumes a rate of 2C/minute
75 Oven attains a temperature of 250C and the
run is terminated.
Retention Times: Lindane (internal standard) elutes at 37 minutes. The
Arochlor 1260 mixture elutes between 41 and 66 minutes.
79
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APPENDIX C
HIGH PERFORMANCE LIQUID CHROMATOGRAPHY
RUN CONDITIONS AND RUN PROGRAMS
Preparing for HPLC Analysis:
Column: Bondapak CIS, 30 cm long with 10 urn diameter packing.
Solvents: A - 1% Aqueous Acetic Acid
B - Acetonitrile
Injection Volume: 100 ul
Flow: 2 ml/min
Oven Temperature: 30C
Recorder settings: chart speed @ 0.50 cm/min;
zero @ 20%;
slope sensitivity @ 0.10;
integrator area reject & 1,000,000,000 area
counts
Run Program for Chlorinated Phenols:
Time (minutes) Action
0 90% solvent A, 10% solvent B
2.0 A solvent gradient of +12.5% B/min is
initiated
4.0 At 35% B a solvent gradient of +4.2%
B/min. is initiated
5.0 Area reject is changed to <100 area counts
10.0 60% B is reached and the solvent gradient
is terminated
80
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Time (minutes) Action
14.0 A solvent gradient of +10% B/min is
initiated
18.0 100% B is reached
25.0 A solvent gradient of -15% B/Min is
initiated
31.0 10% B is reached and the solvent gradient is
terminated
32.0 Stop Run
Retention times: 4-chloro, 3-methylphenol (internal standard) elutes at 8.8
minutes; dichlorophenol at 9.3 minutes; trichlorophenol at
10.5 minutes; and pentachlorophenol at 12.9 minutes.
81
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APPENDIX 0
CALCULATIONS AND QUALITY CONTROL FOR
INSTRUMENTAL ANALYSIS
Calibration and Calculations
o Prior to the analysis of sample extracts, the linearity of detection
for the internal standards and the compounds of interest was
demonstrated. These compounds were analyzed at a minimum of three
concentrations over the range of interest and response factors
generated for each concentration.
RF= Qc
A~
where:
RF = response factor in ng of .compound per GC or HPLC area count
(A)
Qc = quantity of the compound on the GC or HPLC column
(concentration of standard in ng/ul x injection volume in
ul)
o A calibration graph was prepared where the amount (Q) was plotted
against the area count (A). Using this method, the linear range of
detection for the internal standards and the compounds of interest was
determined and all future sample extracts were analyzed within this
range. If a sample was too concentrated or dilute it was reanalyzed
at a concentration which was in the linear detector response range.
o During analysis of a real sample the sample weight or volume was
determined and a known amount of internal standard in methanol was
spiked into the sample.
o Determination of the concentrations of pollutants in a sample was
accomplished through the use of the following equation.
82
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C = Ap Qis RFp
W (or V) Ais RFis
where:
C = concentration of the pollutant in the dried soil (ng/g)
or aqueous leachate (ng/1)
Ap = integrated area under the peak for the pollutant of
interest in the sample extract
RFp = response factor for the pollutant of interest (as
determined by the standard)
Qis = quantity of internal standard (in ng) added to the sample
extract
Ais = integrated area under the peak for the internal standard
in the sample extract
RFis = response factor for the internal standard (as determined
by the standard)
W = weight of dry soil analyzed (in grams)
V - volume of aqueous leachate analyzed (in liters)
This equation corrects for the recovery of the internal standards during
the extraction and concentration steps. The instrument was calibrated (and new
response factors generated) after every 10 injections. This minimized the
effect of instrument performance on reported results.
83
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APPENDIX E1
METRIC CONVERSION TABLE
Metric Unit x
cm
cm/ sec
cm 2
m
g
g/cm3
g/g
kg
1
mg
wT
mg/1
ml
mm
m-Vsec
ng
nm
ug
ug/ml
urn
ul
Multiplier = .
.3937
.3937
.1550
3.2808
0.0353
62.4280
1.0
2.2046
0.2642
3.5274 x lO-5
6.2426 x 10-5
0.0610
0.0394
264;1721
3.5274 x 10'11
3.9370 x lO-8
3.5274 x ID'8
6.2426 x 10~5
3.9370 x 10-5
6.1024 x 10-5
English Unit
in
in/sec
in2
ft
oz
Ib/ft3
oz/oz
Ib
gal
^
oz
lb/ft3
in3
in
gal /sec
oz
in
oz
lb/ft3
in
in3
84
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