PB87-133112
PCB (Poly chlorinated Biphenyl) Sediment "
Decontamination - Technical/Economic
Assessment of Selected Alternative Treatments
Research Triangle Inst.
Research Triangle Park, NC
Prepared for
Environmental Protection Agency, Cincinnati, OH
Dec 86
U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
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PBd7- 1331 12
.EPA/600/2-86/112
December 1986
PCB SEDIMENT DECONTAMINATION-
TECHNICAL/ECONOMIC ASSESSMENT
OF
SELECTED ALTERNATIVE TREATMENTS
by
Ben H. Carpenter
Research Triangle Institute
Research Triangle Park, North Carolina 27709
Contract No. 68-02-3992
RTI Project No. 471U-3065-26
Project Officer
Donald L. Wilson
Hazardous Waste Engineering Research Laboratory
Cincinnati, Ohio 45268
HAZARDOUS WASTE ENGINEERING RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
REPRODUCED BY
U S DEPARTMENT OF COMMERCE
NATIONAL TECHNICAL
INFORMATION SERVICE
SPRINGFIELD, VA. 22161
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TECHNICAL REPORT DATA
(Please read Inunctions on the reverse before completing)
1. REPORT NO.
EPA/600/2-86/112
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
PCB SEDIMENT DECONTAMINATION - TECHNICAL/ECONOMIC
ASSESSMENT OF SELECTED ALTERNATIVE TREATMENTS
5. REPORT DATE
December 1986
6. PERFORMING ORGANIZATION CODE
Research Triangle Institute
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
Ben H. Carpenter
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Research Triangle Institute
P. 0. Box 12194
Research Triangle Park, NC 27709
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12: SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
Hazardous Waste Engineering Research Laboratory
Office of Research and Development
U. S. Environmental Protection Agency
Cincinnati, OH 45268
Final - 6/85-2/86
14. SPONSORING AGENCY CODE
EPA/600/12
IS. SUPPLEMENTARY NOTES
16. ABSTRACT
Eleven emerging alternative treatments for PCB-contaminated sediments have been
compared and ranked using technical performance, status of development, test and
evaluation data needs, and cost as factors. In ranking the processes, weights were
assigned the factors to emphasize the extent of decontamination, the estimated cost
of treatment, and the versatility of the process.
The emerging treatment processes represent six of the nine potentially applicable
types of technologies: low-temperature oxidation, chlorine removal, pyrolysis, re-
moving and concentration, vitrification, and microorganisms. Types of technologies
not developed are chlorinolysis, stabilization, and enzymes.
On the basis of the comparisons made, the treatment processes were ranked in the
following order from highest to lowest: KPEG, LARC, Acurex, Bio-Clean, Supercritical
Water, Advanced Electric Reactor, Vitrification, OHM Extraction, Soilex, Composting,
and Sybron Bi-Chem 1006. The first eight processes show potential for reduction of
PCB concentrations to the desired background levels (1 to 5 ppm) or less, with minimum
environmental impacts and low to moderate cost. All the technologies except the
advanced electric reactor require further development and testing.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Croup
18. DISTRIBUTION STATEMENT
RELEASE TO THE PUBLIC
19. SECURITY CLASS (Thit Report/
UNCLASSIFIED
21. NO. OF PAGES
134
20. SECURITY CLASS
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the
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FOREWORD
Today's rapidly developing and changing technologies and industrial prod-
ucts 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 Environ-
mental Protection Agency, the permitting and other responsiblities of State
and local governments and the needs of both large and small businesses in
handling their wastes responsibly and economically.
This report describes eleven emerging treatment processes that show poten-
tial for decontaminating Polychlorinated Biphenyl (PCB)-contaminated sedi-
ments. The comparisons of these processes in terms of technical performance,
status of development, test and evaluation data needs, and estimated cost of
application should be useful to EPA Regional Offices, to those concerned with
developing hazardous waste treatment regulations, and to those interested in
the development of new and innovative treatments.
For further information, please contact the Alternative Technologies
Division of the Hazardous Waste Engineering Research Laboratory.
Thomas R. Hauser, Director
Hazardous Waste Engineering Research
Laboratory
iii
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ABSTRACT
Eleven emerging alternative treatments for PCB-contaminated sediments have
been compared and ranked using technical performance, status of development,
test and evaluation data needs, and cost as factors. In ranking the process-
es, weights were assigned the factors to emphasize the extent of decontamina-
tion, the estimated cost of treatment, and the versatility of the process.
The emerging treatment processes represent six of the nine potentially
applicable types of technologies: low-temperature oxidation, chlorine re- :
moval, pyrolysis, removing and concentration, vitrification, and micro-
organisms. Types of technologies not developed are chlorinolysis, stabiliza-
tion, and enzymes.
On the basis of the comparisons made, the treatment processes were ranked
in the following order from highest to lowest: KPEG, LARC, Acurex, Bio-Clean.
Supercritical Water, Advanced Electric Reactor, Vitrification, OHM Extraction,
Soilex, Composting, and Sybron Bi-Chem 1006. The first eight processes show
potential for reduction of PCB concentrations to the desired background levels
(1 to 5 ppra) or less, with minimum environmental impacts and low to moderate
cost. All the technologies except the advanced electric reactor require fur-
ther development and testing.
This report was submitted in fulfillment of Contract No. 68-02-3992 Task
26 by Research Triangle Institute under the sponsorship of the U.S. Environ-
mental Protection Agency. This report covers a period from June 1985 to
February 1986, and work was completed as of March 1986.
iv
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CONTENTS
Section
Notice
Foreword
Abstract
Figures
Tables
Abbreviations and Symbols
Acknowledgments
1 Introduction 1
1.1 Background 1
1.2 Purpose 1
1.3 Approach 2
1.3.1 Data Acquisition 2
1.3.2 Screening and Selection of Most Technically
Feasible Processes 2
1.3.3 Development of Criteria 3
1.3.4 Process Assessment 3
1.4 Scope of the Report. 4
2 Conclusions
3 Screening of Alternative Treatment Processes
4 Development of Evaluation Criteria , 12
4.1 Problem Definition 12
4.2 Regulatory Factors 12
4.3 Technical Factors 13
4.3.1 Residual PCB Consideration in Treated
Sediments 14
4.3.2 Available Capacity 14
4.3.3 Conditions/Limitations 14
4.3.4 Concentration Range Handled 14
4.3.5 Status of Development 14
4.3.6 Test and Evaluation Data Needs 15
4.3.7 Unit Operations . . . ..... /..'. '. 15
4.3.8 Estimated Costs 15
4.4 Cost Estimates , 15
4.4.1 Cost Estimation.Methodology ... 15
4.4.2 Baseline Cost Estimate ......:.. 19
4.4.3 Incineration. Cost. Estimate 19
4.4.4 Alternative Treatment Cost Estimate 19
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Section
CONTENTS (continued)
Assessment of Alternative Treatment Processes 20
5.1 Processes Based on Chemical Technologies 20
5.1.1 Supercritical Water Oxidation 20
5.1.1.1 Principles 20
5.1.1.2 Modar SCW Process 21
5.1.2 Nucleophilic Substitution 24
5.1.2.1 Principles 24
5.1.2.2 KPEG Terraclean-Cl Process 26.
5.1.3 Radiant Energy-Ultraviolet Light 38
5.1.3.1 Principles 38
5.1.3.2 LARC Process 39
5.1.4 Pyrolysis 46
5.1.4.1 Prinicple 46
5.1.4.2 Advanced Electric Reactor,
J. M. Huber Corporation 46
5.1.5 Thionation 53
5.2 Processes Based on Physical Technologies 54
5.2.1 Extraction 54
5.2.1.1 Principles 54
5.2.1.2 Acurex Solvent Wash Process 56
5.2.1.3 O.H. Materials Methanol
Extraction Process 60
5.2.1.4 Soilex Solvent Extraction
Process 63
5.2.2 Vitrification 67
5.2.2.1 Principles 67
5.2.2.2 Battelle In Situ Vitrification
Process 67
5.3 Biological Technologies 71
5.3.1 Microorganisms and Enzymes 71
5.3.1.1 Principles 71
5.3.1.2 Indigenous and Conventional
Chemical Mutants 72
5.3.1.3 Enzyme Mechanisms 77
5.3.1.4 Bio-Clean Process 78
5.3.1.5 Sybron Bi-Chem 1006 PB/Hudson
River Isolates Process 81
5.3.1.6 Composting 83
5.4 Supporting Processes 84
5.4.1 Dredging 85
5.4.1.1 Classes of Dredge 85
5.4.1.2 Dredge System Evaluation 88
5.4.2 Wastewater Treatment Methods 91
5.4.2.1 Mechanical Removal " 91
5.4.2.2 Activated Sludge 91
5.4.2.3 Trickling Filter 92
5.4.2.4 Special Biological Treatment
Processes 92
5.4.2.5 UV/Ozonation 93
5.4.2.6 Carbon Adsorption 93
vi
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Section
CONTENTS (Continued)
Characterization and Ranking of Alternative
Treatment Processes 95
6.1 Characterization 95
6.2 Ranking of Treatment Processes 98
6.2.1 Residual PCB Concentration in
Treated Sediments 102
6.2.2 Available Capacity 102
6.2.3 Conditions/Limitations 102
6.2.4 Concentration Range Handled 103
6.2.5 Status of Development 103
6.2.6 Test and Evaluation Data Needs 103
6.2.7 Estimated Costs 104
6.2.8 Overal 1 Ranking 104
Bibliography 107
vii
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FIGURES
Page
1 Schematic of the Modar SCW oxidation process 22
2 Schematic of KPEG process 28
3 Schematic of scaled-up KPEG process 31
4 Schematic of dioxin-treatment system 32
5 Schematic of single-lamp LARC reactor 40
6 LARC degradation of Aroclor 1260 in basic
isopropanol . . 43
7 Schematic of LARC mobile unit for destruction
of PCB's in soil 45
8 Vertical cross section of the Advanced
Electric Reactor 47
9 Schematic of Advanced Electric Reactor process 49
10 Schematic of Acurex solvent wash process 59
11 Conceptual flow sheet, methanol extraction of
PCB's from discussion with Robert Caron, EPA,
Philadelphia regional office 61
12 Soilex pilot plant 64
13 Soilex steam distillation unit 66
14 Engineering scale vitrification system and sample
locations 69
15 Bio-Clean process applied to contaminated soils 80
16 Alternative treatment costs, PCB D/D/R processes 101
viii
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TABLES
Number Page
1 Screening of PCB Treatment Processes 8
2 Unit Cost Estimates for Steps Involved in Treatment
and Disposal of PCB-Contaminated Sediments 18
3 Extraction Data for Chlorinated Organics from Soil 42
4 Extraction of PCB's from Soil, Effect of Tween 55
5 Results of Soil Cleaning Tests, Acurex Solvent
Washing Process 57
6 PCB Degradation by Bacterial Strains: Percent
Degradation by Cogener (Rapid Assay Test) 74
7 PCB Degradation by Bacterial and Fungal Strains:
Longer Tests .' 75
8 Dredge Evaluation Matrix; Spill Scenario: Land and
Nonnavigable Waters—All Spill Sizes . . . . 89
9 Dredge Evaluation Matrix; Spill Scenario: Rivers—All
Spill Sizes 90
10 Treatment Process Assessment 96
11 Treatment Process Assessment 99
12 Ranking of Emerging Treatments for PCB-Contaminated
Sediments , 106
ix
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LIST OF ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
AER — Advanced Electric Reactor
ATP — Adenosine triphosphate
CFR — Code of Federal Regulations
COD — chemical oxygen demand
CWO — catalyzed wet oxidation
D/D/R — destruction/detoxification/reraoval
DE — destruction efficiency
DMSO — dimethyl sulfoxide
DNA — deoxyribonucleic acid
ISV — in situ vitrification
kcal — kilocalorie
KPEG — potassium poly(ethylene glycolate)
%CV's — percent coefficients of variability
MT -- metric ton
PCB(s) — polychlorinated biphenyl(s)
PEG — poly (ethylene glycol)
PEGM — poly (ethylene glycol methyl ether)
PRTZ — post-reactor treatment zones
RCRA — Resource Conservation and Recovery Act
scfm — standard cubic feet per minute
SCM — standard cubic meter
TSCA — Toxic Substances Control Act
UV — ultraviolet
x
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SYMBOLS
A — angstrom
atm — atmosphere
CC14 — carbon tetrachloride
d -'- day
g — gram
g/L — grams per liter
h — hour
HC1 — hydrogen chloride
kWh — kilowatt hour
m — meter
m^ — square meter
Mg — megagrams
mg/L — milligrams per liter
mitt — minute
nm — nanometer
pd — palladium
ppb — parts per billion
ppm — parts per million
ppt — parts per trillion
Ug/mL — micrograms per milliliter
V — volt
wk — week
# — pound
g/mL — grams per milliliter
METRIC CONVERSIONS
1 gal = 3.785 L
1 Ib = 0.4536 kg
1 yd3 = 0.7646 m3
xi
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ACKNOWLEDGMENTS
The contributions, guidance, and advice provided by the EPA Technical
Project Manager, Donald L. Wilson, and by Charles J. Rogers, Chief. Chemical
and Biological Staff, are gratefully acknowledged. At RTI. the study was
conducted under the supervision of Dr. Forest 0. Mixon, Jr., Vice President,
Chemical Engineering. Ms. Coleen M. Northeim conducted the literature search.
Several proponents of emerging technologies provided descriptions, test data.
and cost estimates for their developing PCB treatments, which are presented in
the ranking and evaluation sections of this report. Their contributions are
also gratefully acknowledged and are referenced throughout the report.
xii
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SECTION 1
INTRODUCTION
1.1 BACKGROUND
The PCB contamination problems in New Bedford. Massachusetts, the Hudson
River in New York, and in Waukegan, Illinois, are reported to be the worst in
the United States in terms of concentration and total quantity of PCBs. Also.
there are numerous industrial lagoons contaminated with large quantities of
PCBs. Dredging to decontaminate harbors/rivers and lagoons is only a partial
solution to the problems until effective disposal/treatment methods for
dredged PCB-contaminated sediments become available.
The EPA Regional Offices have been asked to comment on the technical and
economic feasibility of processes proposed for the cleanup of these sediments
and sludges. The Regional Offices do not have adequate data to recommend any
specific process from a number of processes currently being proposed or
tested/evaluated for the removal of PCBs from contaminated sediments.
1.2 PURPOSE
This study was undertaken for three main reasons: to identify the most
technically feasible processes that have been proposed by research concerns
for the removal of PCBs from sediments: to identify their extent of develop-
ment, effectiveness, limitations, and probable costs; and to compile a report
describing the technical and economic data available on such processes. The
primary objective was to identify the most promising process(es) and to deter-
mine needs for further development.
This is the first phase of three phases of study." Future phase two will
deal with the evaluation of the unit operations involved in the processes,
examine them further against engineering, health, and environmental criteria,
and recommend three of them for further testing and evaluation. Phase three
will address a definitive assessment of these alternative treatment processes
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using bench or pilot systems and representative contaminated sediments. On-
going related work by the EPA Technical Evaluation Staff at Edison, New Jersey
is addressing the adaptation of existing commercial extraction technologies to
removal of contaminants from solids (soils, sediments, etc.), the characteri-
zation of superfund site contamination, and pilot-scale studies of extraction,
using water with additives (particulates, chelating, phase-transfer, etc.).
1.3 APPROACH
The study involved four phases: data acquisition, screening and selection
of the most technically feasible processes, development of criteria for proc-
ess assessment, and process assessment.
1.3.1- Data Acquisition
Three major sources of data were EPA's Technical Project Officer, the open
literature, and direct contacts with proponents of treatment technologies.
EPA's file of proposals and correspondence concerning problems of PCB contam-
ination and possible approaches to alternative solutions proved invaluable in
directing the contacts for further information.
A bibliography was prepared, which included approximately 100 references
containing information useful in defining potential treatment technologies and
in analyzing treatment process performance data. This bibliography was ex-
panded to 171 references by addition of treatment feasibility study reports.
process test and evaluation reports, process development proposals, and
patents. As processes were identified, direct contacts were made with the
investigators for details of their process studies. These contacts are
identified throughout the text.
1.3.2 Screening and Selection of Most Technically Feasible Processes
Alternative (non-incineration) destruction/detoxification/removal (D/D/R)
processes were subjected to screening to identify those to be assessed fur-
ther. The processes were categorized according to their generic technology so
that appropriate technical screening criteria could be applied for each. This
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screening yielded 11 emerging processes for further assessment. The selected
processes represent six different generic technologies.
1.3.3 Development of Criteria
Criteria used to assess the identified emerging technologies included:
residual PCB concentration in treated sediments, available capacity, condi-
tions/limitations (including range of PCB concentration handled), the develop-
mental status, test and evaluation (T and E) data needs, and estimated cost of
treatment.
1.3.4 Process Assessment
The assessment of the different processes required consideration of the
characteristics inherent in the criteria. Their capability to remove PCBs
adequately from wet contaminated sediments, the required processing time, and
process controllability were all considered. Available data were examined for
limits on the range of PCB concentrations that could be adequately reduced by
the process to yield a treated sediment eligible for delisting. The status of
development, whether laboratory-scale or pilot-scale, was identified. The
extent of available data - whether showing only tests of the concept or lists
of the unit processes of a pilot-scale process system - was identified. A
preliminary estimate of the cost of applying the process was developed in
conjunction with the Developer.
Because the processes identified were at various stages of development,
data deficiencies exist, and engineering judgement was used to supplement
available information.
Using the information obtained and developed, the characteristics for each
process were given subjective ratings relative to an arbitrarily-defined per-
fect process. These ratings were then weighted and summed to give a single
number that could represent the overall relative rating of each process.
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1.4 SCOPE OF THE REPORT
Section 3 of this report describes the screening of alternative tech-
nologies for technical feasibility to treat PCB-contaminated sediments. Sec-
tion 4 describes the development of criteria to assess selected processes.
Section 5 describes the assessment of the processes, including descriptions,
analyses of performance potential, and cost estimates. Section 6 summarizes
the characteristics of the selected processes and ranks them subjectively.
Section 7 presents a bibliography of references used and other relevant
sources. Contacts with developers of the processes are noted throughout the
text.
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SECTION 2
CONCLUSIONS
Emerging treatment processes for decontamination of PCB-contarainated sedi-
ments that show potential as alternatives to incineration and chemical waste
landfill have been identified. Eight processes — KPEG, LARC. Acurex, Bio-
Clean, Supercritical Water, Advanced Electric Reactor, Vitrification, and
O.H.M. Extraction — rank highest in terms of potential for cleanup of contam-
inated sediments. The sediments must be dredged for application of these
treatments.
Of the 11 processes assessed, all but the Advanced Electric Reactor (AER)
are in various stages of development from laboratory-scale through field
tests. The AER is a permitted treatment based on completed trial burns.
There is no immediately available capacity for any of the treatments.
Further data are needed in most cases to define the final system design for
the process.
At this stage of development, estimated costs of application of the emerg-
ing treatments are less than or within the range of the costs of chemical
waste landfill, except the AER estimated cost, which exceeds that of landfill
but is below the cost of incineration. The ranges of estimated costs (1985
dollars) are as follows:
KPEG
O.H.M. Methanol Extraction
Advanced Electric Reactor
Acurex solvent wash
Bio-Clean
Vitrification
LARC
Modar supercritical water
Sollex solvent extraction
Sybron Bi-Chem 1006 PB
Composting
Chemical waste landfill
Incineration
i 211 to $ 378/m3
400 to 514/m3
830 to 942/m3
196 to 569/m3
191 to 370/m3
255 to 548/m3
223 to 336/ra3
250 ' to 733/m3
856 to 913/ma
unable to estimate cost
unable to estimate cost
260 to 490/m3
1,713 to 1,826/m3
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These costs are planning estimates only. In most cases, further research is
needed to provide data suitable for more definite cost estimates.
The emerging treatment processes are based on six different technologies:
one on low-temperature oxidation, two on chlorine removal, one on pyrolysis.
three on removing and concentrating, one on vitrification, and three on micro-
organisms. Types of generic technologies not yielding competitive emerging
processes are: chlorinolysis, stabilizing, and enzymes. A search of these
technologies yielded no suitable candidate processes at. this time.
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SECTION 3
SCREENING OF ALTERNATIVE TREATMENT PROCESSES
This section describes the screening of all processes disclosed in the
acquired data to select those to be assessed further as potential alternative
treatments for PCB-contaminated sediments. The processes were screened by
examining each for any undesirable aspects. Processes with such aspects were
rejected from further assessment. For example, lack of tolerance for water by
a process is undesirable because of the extensive sediment drying it necessi-
tates. There is evidence in the collected data that such drying generates
fine particulates that must be removed from the exit gases of the dryers. The
recovered particulates must also be decontaminated. Processes showing insuf-
ficient tolerance for water were therefore rejected from further consideration
as a primary treatment process in favor of more tolerant alternatives.
Table 1 lists the processes screened, identifies those selected for fur-
ther assessment, and gives the reasons for rejection of the rest. The proc-
esses are arranged according to the generic types of technologies upon which
they are based. The use of generic technology types guided the survey and
assessment phases of this study by providing technologies from which treatment
processes could arise. Some of the technologies (e.g., nucleophilic substitu-
tion) have provided several processes. Some (e.g.. enzymes) have not yet
provided any processes. These technologies are nevertheless discussed to
describe their status, with respect to PCB-contaminated sediment treatment, so
that their potential may be considered in research planning.
A process rated "1" in Table 1 for each technology has been selected for
further assessment and will be discussed in Section 5. Higher rating numbers
assigned the rest of the screened processes refer to footnotes that identify
the reason for rejection of the process for further assessment.
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TABLE 1. SCREENING OF PCS TREATNBTC PROCESSES
Generic
technology
References
Process
Evaluation13
CHEMICAL
Lew-temperature oxidation
Wet air oxidation
Centofanti 1971; Chan 1982; Childs 1982;
Craddock 1982; Edwards et al. 1982;
Environment Canada 1983; Homig 1984;
Massey and Walsh 1985; Rogers and Kernel
1985; Rogers 1983; Rogers 1985.
Baillodet al. 1978; Miller and
Sevientoniewski (n.d.); Miller and fox
1982.
Supercritical water oxidation Modell et al. 1982.
Chemical oxidants
Ozonation
Chlorine removal
Oehydrochlorinaticn
Reducing agents
Nucleoohilic substitution
FMC Corporation (n.d.); March 1968.
Arisman et al. 1981; Lacy and Rice
Oeschlaeger 1976; Prengle and MauK1978.
U.S.P. 346, 636
Chu and Vick 1985; Lapiere et al. 1977.
Chu and Vick 1985; Sworzen and Ackeraan 1982.
8rom et al. 1985a; Srunelle and Singleton
1985; March 1968; New York university 1984;
Ruzz et al. 1985; Smith and Qurbachan 1981;
Sunohio (n.d.); Sweeny and Fischer 1970;
United States Patent Office 1984b; Heitzman
1984; Weitzman 1984; Weitzman 1985.
Uncatalyzed, general 2
Zimoro Process, Santa Maria, 4,13
CA Waste Site
Catalyzed
Ocw Chsmical Co. Patent 3,984,311 2
IT Environmental Science 2
Mcdar 1
Potassium permanganate plus Chromic
Acid and Nitric Acid 5
Chloroiodides 4,7
Ruthenium tetroxide 3,4,8
G£ UV/ozonatien process 2
ttolten aluminum/distillation 14
Catalytic: 2,3
Nickel on kieselguhr 2,3
Pd on charcoal 2.3
Lithium aluminum hydride 2,3
Butyl lithium 2.3
Raney Nickel 2,3
Sodium in liquid ammonia 7,9
Nickel-catalyzed zinc reduction 7,9
Hydrazine 7,9
UV light plus hydrogen 2
Mildly acidic zinc powder,
Sweeney and Fisher (1970) 2,14
Sodium-based-processes:
Goodyear, sodium in naphthalene (1980) 10
Acurex, proprietary solvent 10
PC8X/Sun Ohio 10
PPM 10
Ontario Hydro Power 10
(continued)
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TA8LE 1 (continued)
Generic
technology
References
Process
Evaluation3
Nucleophilic substitution
.(continued)
Radiant energy
Sail in and Hertzler 1977; Bail in and
Hertzler 1978; Bailin et al. 1978;
Craft etal. 1975; Oevetal. 1985;
Kalmaz et al. 1981; Meuser and Weimer 1982;
Plimner 1978; Rogers and Kernel 1985;
Rogers 1985; Trump et al. 1979; West et al.
1983.
Electromechanical reduction Massey and Itelsh 1985.
Chlorinolysls Sworzen and Ackerman 1982.
Pyrolysis
PHYSICAL
Removing and concentrating
Heated Air Stripping
Extraction
Adsorption
Vitrification
Goyd 1985; New York State Department of
Environmental Conservation 1985a; New
York State Department of Environmental
Conservation 1985b.
Angiola and Soden 1982; Caron 1985; Gilmer
and Freestone 1978; Githens 1934; Handler
et al. 1984; Hawthorne 1982; Lee et al.
1979; Saunders 1985; Schwim et al. 1984;
Versar. Inc. 1984.
Potassium poly (ethylene glycolate)
based:
EPA In-tause KPEG
KPEG Terraclean-C1
GEKQH-PEG
New York university KPEG
UV/photolysis
Syntex photolytic
Thermal corona glow
Microwave plasma
RF insitu heating
radiation (Craft et al. 1975)
LARC
Electromechanical research process
Hoechst process
Goodyear catalytic hydrogenolysis
Exhaustive chlorinaticn
1
i
11
12
5
3,17
13
9
1
14
9
9
9
Advanced Electric Reactor I
Wright-Malta alkaline catalyst fuel-gas
process 12
Timmennan 1985.
American Toxics Disposal, Inc. 14
Critical Fluid Systems, COj 14
Furfural 15
Acurex solvent wash 1
0. H. «. extraction 1
Soilex process 1
Carbon adsorption, general 13
Neoprene rubber adsorption 15
Battelle vitrification process 1
(continued)
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TABLE 1 (continued)
Generic
technology
References
Process
Evaluation3
Stabilizing
Bottom recovery
8IOLOGICAL
Microorganisms
Ghassenri and Haro 1985; Law Engineering
Testing Company 1982; Straud et al. 1978;
Subnamanian and Mahalingam 1977; Tittlebaum
et al. 1985.
Carich and Tofflemire 1983; Hand and Ford
1978; Murakami and Takeishi 1978; U.S. Army
Corps of Engineers Water Resources Support
Center 1983; Ziimrie and Tofflenire 1978.
Bedard et al. 1985; 8unpus et al. 1985;
Clark et al. 1979; Oaves and Sutherland
1976; Furakawa 1982; Isbister et al. 1984;
Kong and Sayler 1983; teCormick 1985;
New York State Department of Environmental
Conservation 1985a; New York State Depart-
ment of Environmental Conservation 1985b;
Rhee et al. 19856; Rhee et al. 1985;
Unterman et al. 1985.
Catelani et al. 1971; tochkind et al.
Unterman et al. 1985.
Asphalt with lime pretreatment
Z-Impremix
Sulfur-asphalt blends (K-20)
Ground freezing
Dredging
8io-C1ean
Sybron 8i-Chem 1006 P8
Composting
Bio-Surf
Ecolotrol, Inc.
Wormes Siochemical's Phenobac
Rhee anaerobic degradation
No processes found
16
15
16
13
13
1
1
1
4,13
4,13
1,13
14
aExplanaticn of process rating:
1. Identified emerging sediment treatment process.
2. Destruction efficiency appears to be too low to meet environmental goals.
3. Processing time appears to be extremely long for practical timely cleanup.
4. Data available for dioxin, other chlorinated compounds, or other contaminants, but not PCB's.
5. Process has been shew to destroy PCB's in gas streams only. It may be feasible for sediments, but has not been show to
be.
6. PCB's with 5-7 chlorine atoms per molecule are not destroyed.
7. Products of partial degradation may be toxic.
8. Reagent is very costly/toxic or both.
9. Process costs appear to be excessively high compared with other emerging treatment processes.
10
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10. Water destroys the reagent or interferes with its action, ttus the process would require excessive drying of sediments and,
probably, extraction in pretreatments. The process would therefore have application only as a subordinate final step to
several extraction and concentration operations.
11. This particular process was not evaluated because data were'not available for assessment.
12. This process is an alternative to another process using the same generic technology, but it is in very early stages of
development, and data were not available for assessment.
13. This technique is basically applicable to preliminary operations prior to treatment or to treatment of wastestreams (e.g.,
wastewaters) from chemical or physical treatments.
U. This process is in the concept stage and data are insufficient to assess it for PCS-contaoinated sediments.
15. This process has been found to be ineffective.
16. This technology provides only for encapsulation of the PC8-ccntaminated sediments.
17. This process supports incineration of PCS's.
18. The process does not appear to be feasible for submerged sediments.
11
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SECTION 4
DEVELOPMENT OF EVALUATION CRITERIA
4.1 PROBLEM DEFINITION
The PCB contamination problem in the Hudson River is representative of the
type of PCB destruction/detoxification problems focused on in this study. The
New York State Department of Environmental Conservation (DEC) recently con-
cluded a 2-year survey of 40 miles of the upper Hudson River (1976-1977). The *
survey, conducted with consultant Malcolm Pirnie, Inc. (White Plains, New
York) identified 40 spots collectively containing more than an estimated
382.000 m3 (500,000 yd3) of sediment contaminated with PCBs at concentrations
greater than 50 ppm. The depth of contamination seems to be between 0.25 and
0.45 meters. A more recent survey (1984) was made of a 5-mile reach extending
downstream 5 miles from Ft. Edward, New York. Samples from the near-shore
area showed from 40 to 60 ppm PCBs (M. P. Brown 1985).
A pilot dredging operation, performed with hydraulic dredges between 1978
and 1979, netted 152,900 m3 (200,000 yd3) of material with seemingly little
dispersion of the contaminant downstream. The contaminated areas are located
in shallow, slow-moving waters near the riverbanks.
Although DEC is investigating other disposal methods, it is expected to
dredge the contaminated sediments and bury them because of the high costs of
alternatives (ENR, January 9, 1986).
The wetness of the sediments will preclude the use of many treatment proc-
esses designed to treat PCB-containing oils using reagents that would be
destroyed or made ineffective in the presence of water.
4.2 REGULATORY FACTORS
The goal for detoxification/destruction is to have no more than 1 to 5 ppm
PCBs in the treated sediment. At present, PCB disposal is regulated under
TSCA [40 CFR 761.60 a 5 (i-iii)J: 12
-------
(5) All dredged materials and municipal sewage treatment
sludges that contain PCBs at concentrations of 50 ppm or
greater shall be disposed of:
(i) In an incinerator which complies with 761.70,
(ii) In a chemical waste landfill which complies with
761.65*; or
(iii) Upon application, using a disposal method to be approved
by the'Agency's Regional Administrator in the EPA Region
in which the PCBs are located. Applications for disposal
in a manner other than prescribed in (i) or (ii) of this
section must be made in writing to the Regional Admin-
istrator. The application must contain information that,
based on technical, environmental, and economic consid-
erations, indicates that disposal in an incinerator or
chemical waste landfill is not reasonable and appropri-
ate, and that the alternate disposal method will provide
adequate protection .to health and the environment. The
Regional Administrator may request other information that
he or she believes to be necessary for evaluation of the
alternate disposal method. Any approval by the Regional
Administrator shall be in writing and may contain any
appropriate limitations on the approved alternate method
for disposal. In addition to these regulations, the
Regional Administrator shall consider other applicable
Agency 'guidelines, criteria, and regulations to ensure
that the discharges of dredged material and sludges that
contain PCBs and other contaminants are adequately con-
trolled to protect the environment. The person to whom
such approval.is issued must comply with all :
limitations contained in the approval.
The criterion of 1 to 5 ppm for a promising alternative treatment should
result in a treated sediment that is disposable without restriction.
4.3 TECHNICAL FACTORS
Technical factors relate to a broad range of principles of operation of
diverse applied technologies. Factors have been chosen that can be used
effectively in comparing one treatment process with another. Additional
*The reference CFR 761.65 in 5 (ii) cited above is apparently an error
because this part of the regulation covers .temporary storage for dispos-
al. Chemical waste landfill compliance requirements are cited as CRF
761.75 in other parts of the regulations. •••'.:
13
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factors, specific to a technology, have been chosen to help portray the inher-
ent strengths and limitations of a process.
4.3.1 Residual PCB Concentration in Treated Sediments
The goal set for process performance is to reduce the PCB concentration in
treated sediments to background levels of 1 to 5 ppm. Several of the process-
es were found to meet this goal.
4.3.2 Available Capacity
Available capacity was found not to exist for any of the processes. How-
ever, several were developed sufficiently to permit projections of the time
required to build a facility for application of the treatment.
4.3.3 Conditions/Limitations
Conditions/limitations that were considered included tolerance for water,
required processing time, and controllability of process conditions. Those
treatments that could tolerate water up to about 40 percent would not require
a drying step with its attendant fines control problems. Those requiring only
1 day for treatment could generally show a faster rate of cleanup than those
requiring 3 days. Some biological processes required more than 3 weeks. The
treatments generally provided control of the processing conditions; however, a
few (e.g., composting) would not necessarily do so.
4.3.4 Concentration Range Handled
Concentration range handled in data developed for the processes ranged
from unknown to 3.000 ppm. Some processes had limits inherent in the tech-
nology; others had no apparent limits.
4.3.5 Status of Development
Processes were found to range from concept stage to completed field tests.
Most were in the pilot stage.
-------
4.3.6 Test and Evaluation Data Needs
Data needs varied with the' status of the process. At worst, data were
available showing tests of the concept. At best, the process had been field
tested, and only permits and checkout were needed.
4.3.7 Unit Operations
Unit operations employed in each process were identified. Collectively,
the processes use 18 different unit operations. The number of operations per
process varied from two to eight, depending upon the complexity of the tech-
nology.
4.3.8 Estimated Costs
Estimated costs (obtained as described in Section 4.4) were assembled
graphically (see Figure 16 in Section 6).
4.4 COST ESTIMATES
4.4.1 Cost Estimation Methodology
Costs of applying an alternative technology are very difficult to predict
because of the uncertainties regarding the potentially available new treatment
processes. Estimates of the quantities of PCB-contaminated sediments are
under review and may change significantly as a result of the reviews. In most
cases, additional information is needed regarding the yet to be proven effec-
tiveness of emerging treatment processes before the costs of their application
can be assessed accurately. Therefore, the cost estimates presented here
should be viewed as preliminary with respect to the new treatment processes.
A range of costs is given for supporting operations (dredging and transporta-
tion) to reflect differences in different geographical areas of the country.
Because the regulations permit the use of incineration or chemical waste
landfill and the application costs of these two methods are available from
firms engaging in their practice, .these costs were used as lower and upper
limits with which to compare the costs of applying new alternative technology.
15
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This provides a range of costs within which the alternative treatment proc-
esses could become attractive economically.
The application of any treatment process can involve the need for one or
more of the following unit operations: dredging, transport, storage, landfill
disposal, land treatment disposal, incineration, and/or alternative treatment.
Estimates have been developed for all of these so that, in any given process-
ing evaluation, the proper elements could be added to obtain an estimate of
the cost of application. The estimates were made in terms of the cost per
cubic meter of sediment treated. The sediment was assumed to have a density
of 1.68 Mg/m3.
The alternative treatment costs are based on current law; we assume that
the treated sediments will be delisted.
Dredging costs for those treatments requiring removal of the sediment
before treatment are estimated at $20/m3 based on the recent experience of the
U.S. Army Corps of Engineers in contracting for dredging in the New York State
area (Wheeler 1986).
Transport costs are given as a range. The Corps' experience is $13/m3 for
short hauling distances. A cost of $126/m3 was used for long hauling dis-
tances, which represents an assumed 483-km average transport distance to RCRA
landfills capable of accepting PCB-contaminated wastes (Industrial Economics.
Inc., 1985).
Storage cost will sometimes be incurred to hold the dredged sediments
pending treatment; e.g., where dredging rates exceed the rates at which the
treatment can be applied. These have been set arbitrarily at $10/m3.
Land treatment involves the controlled application of wastes to the sur- ,
face of the soil. At land-treatment facilities, wastes are either spread on
or injected into the soil, followed by tilling into the soil with farm equip-
ment. The physical and chemical properties of the soil, in unison with the \
biological component of the soil and sunlight work together to immobilize,
degrade, and transform portions of the wastes. The application and tilling
process can be repeated many times on the same plot, making land treatment a
16
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dynamic system designed to reduce and ultimately eliminate a portion of the
waste, as opposed to permanent storage such as landfills.
The American Petroleum Institute (1983) has reported that there were 213
land-treatment facilities In operation handling waste from 16 different .indus-
try sectors. The most extensive use of land treatment is for petroleum
refinery wastes, with 105 land-treatment facilities, many of which are located
on the same site as the refinery. More recently. EPA verified the existence
of 114 land-treatment facilities and obtained information on operating parame-
ters at some of these sites (Thomeloe, 1986).
Wastes are typically mixed to a depth of 0.5 to 1.0 feet, where biochemi-
cal reactions take place. Application frequencies can range from daily to
yearly, with tilling occurring as frequently as daily.
The average cost of controlled, managed land treatment cited by the
American Petroleum Institute, $60/ton, equates to $lll/m3 of sediments. For
short-term land treatment of readily-degradable solvents remaining in treated
sediments free of PCBs after they are washed or dried, the cost is estimated
at $33/m3 (Caplan. 1986).
« *
Redeposition costs of decontaminated sediments were also estimated at
$33/m3. Slightly lower costs might be expected in special cases.
Landfill disposal costs, incurred when the sediments must be placed in
authorized chemical waste landfills, are estimated as ranging from $260/m3 for
the Michigan area (CPA Regional Office) to $490/m3. based on the highest
prices charged for hazardous wastes by commercial facilities (Industrial
Economics, Inc.. 1985). This range includes an intermediate value reported by
the Corps of Engineers: $420/m3.*
*The New York State Department of Environmental Conservation has estimated
that the costs of permitting and constructing a landfill facility for the
Hudson River PCB Reclamation Demonstration Project would be approximately
$25/m3 (M. P. Brown, 1986). The estimate includes site construction and cover
costs, but does not include line items for land, overhead, profit, subsequent
monitoring, and insurance costs. Since alternative treatment costs cited
herein include overhead, profit, and insurance, they have been compared with
the higher landfill costs cited above. . -
17
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Costs for incineration techniques capable of achieving 99.9999 percent
destruction and removal efficiencies for PCBs are difficult to predict. Even
more difficult is prediction of the price commercial facilities will charge to
accept the responsibility of handling such a sensitive waste. Surveys made to
determine the likely charges to incinerate dioxin-containing wastes resulted
in a reported price on the order of $l,000/Mg (Pope-Reid Associates 1985).
This translates to $l,680/m3. the value adopted for this evaluation, and the
cost of disposal of residue from incineration is included. The total cost of
use of incineration including dredging at $20/m3 and transport at $13 to
$126/m3 is $1713 to $1826/m3.
When available, alternative treatment costs were obtained from the propo-
nent of the process. Otherwise, they were estimated based on the types of
unit processes involved and the environmental controls required, or they were
determined not to be estimable considering the status of development of the
process.
While all costs are in 1985 dollars, the treatment costs are not all
necessarily based upon the same labor rates, corporate fixed charges, or
profit. These costs vary from one firm to another. The cited estimates are
costs of purchasing the treatments. Further cost analyses will be needed to
provide a basis for comparison of processes on the basis of individual cost
elements.
Table 2 shows the unit cost estimates used to develop cost ranges for the
emerging treatments.
TABLE 2. UNIT COST ESTIMATES FOR STEPS INVOLVED IN TREATMENT
AND DISPOSAL OF PCB-CONTAMINATED SEDIMENTS
Operation Cost, $/m3
Dredging 2O
Transport 13 to 126
Storage 10
Landfill disposal 260 to 490
Land treatment 33 to 111
Incineration 1,680
18
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4.4.2 Baseline Cost Estimate
Baseline costs are taken as the range of costs for sediment removal,
transport, and disposal in a chemical waste landfill. This range is calcu-
lated using the unit costs from Table 2:
Baseline costs, $/ra3 = dredging cost and transport cost + disposal cost
= $20 + $13 to $126 * $260 to $490
= $293 to $636.
4.4.3 Incineration Cost Estimate
Incineration costs include those for dredging, transport, and in-
cineration. The cost of residue disposal is included in the incineration
cost:
Incineration cost, $/m3 = dredging cost + transport cost + incineration
cost
= $20 + $13 to $126 + $1,680
= $1,713 to $1.826.
4.4.4 Alternative Treatment Cost Estimate.
The costs' of alternative treatments are calculated in the same way, by
summing the costs for the separate operations involved.
19
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SECTION 5
ASSESSMENT OF ALTERNATIVE TREATMENT PROCESSES
The processes assessed in this section represent six different technolo-
gies; each of which is briefly described prior to discussing the processes to
which it applies. For the process themselves, the depth of presentation
varies because of the varying extent of available information.
5.1 PROCESSES BASED ON CHEMICAL TECHNOLOGIES
5.1.1 Supercritical Water Oxidation
5.1.1.1 Principles—
The supercritical water (SCW) oxidation process is a relatively low •
temperature oxidation process that utilizes temperatures and pressures of
supercritical water (above 374 °C and over 22.09 MPa) to break down hazardous
organics to carbon dioxide, water, and other simple, less harmful molecules.
The treatment is not selective but rather applicable to a broad range of com-
pounds. Normally water-insoluble organics become highly soluble in super-
critical water. The water also acts to reform complex organics, and hetero-
atoms, including halogens, phosphorous, sulfur, and metals, are readily pre-
cipitated as salts when present with appropriate counter-ions.
In the supercritical region, water exhibits properties far different from
normal water. The density of supercritical water (0.05 to 0.3 g/ml.) is low
enough and the temperature high enough to essentially eliminate hydrogen bond-
ing. As a result, the dielectric constant is reduced from 80 to less than 2,
and water becomes a good solvent for organic substances (Thomason and Model1
1984). In contrast, inorganic salts become only sparingly soluble. Thus, the
solubility characteristics of supercritical water are the inverse of those of
normal liquid water.
In water above 350 °C, organic materials reform to low molecular weight
products. Whereas many organic compounds tend to form a high molecular weight
20
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char at temperatures below 350 °C, in supercritical water the same organics
are reformed to gases (e.g., CO, H2. CH4, CC^) and volatile organic liquids
(alcohols, aldehydes, furans) without producing char.
The products of supercritical water reforming can be subjected to oxida-
tion while still under supercritical conditions. The residence time usually
required for oxidation is less than 1 minute, which greatly reduces the volume
of the oxidizer vessel. In addition, oxygen is completely miscible with
supercritical water, and the oxidation can be conducted under homogeneous
(i.e., single-phase) conditions. Contaminated sediments may not contain suf-
ficient organics. and supplementary fuel would be required to maintain reac-
tion temperatures.
When toxic or hazardous organic chemicals are subjected to SCW oxidation,
carbon is converted to 003 and hydrogen to 1^0. The chlorine atoms from
chlorinated organics are liberated as chloride ions. Similarly, nitrogen
compounds will produce nitrogen gas, sulfur can be converted to sulfates,
phosphorous to phosphates, etc.* Upon addition of appropriate cations (e.g.,
Na*. Kg**, CA'1"1"), inorganic salts can be formed.
When the concentration of organics is above 5 percent by weight, the heat
of oxidation is sufficient to bring the supercritical, stream to temperatures
in excess of 550 °C. At these conditions, inorganic salts have, extremely low
solubilities in water. Inorganic salts will be precipitated out and readily
separated from the supercritical fluid. After removal of inorganics, the
resulting fluid is a highly purified stream of water at high temperature (>500
°C) and high pressure (25.5 MPa). It can be used as a source of high-
temperature process heat. •
;
5.1.1.2 Modar SCW Process—
A schematic flow sheet for the MODAR process as applied to soil-slurry
decontamination is presented in Figure 1. The process consists of the follow-
ing steps: " ;
1. PCB-contaminated sediments are fed as a slurry with 20 to 40 percent
solids, as determined by some continuous flow bench-scale testing'and
'Personal communication. William R. Killilea to Donald L. Wilson. April 11,
1986.
21
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IV
Slurry Tank
Slurry
Pump
Oxygen Oxygen
Pump Preheater
Gas Effluent
f
»-
Slurry
Preheat
Exchanger
,
Gas/Li
Separi
anc
Letdc
^
Recycle Pump
Oxidizer
Solids
Separator
Solids
Letdown
Solids
Receiver
Figure 1. Schematic of the MODAR SCW oxidation process for sediment decontamination.
Liquid
Effluent
-------
preliminary economic studies. The slurry is pressurized to super-
critical pressure then heated by heat exchange with oxidizer effluent
generated in a subsequent step.
2. At the oxidizer. pressurized oxygen, organic fuel, preheated slurry
and oxidizer recycle are brought together. Because the water is
supercritical, the oxidant is completely miscible with the solution
(i.e.. the mixture is a single, homogeneous phase). Organics are
oxidized in a controlled but rapid reaction. Because the oxidizer
operates adiabatically, the heat released by combustion of readily
oxidized components is sufficient to raise the fluid phase to tempera-
tures at which all organics are oxidized rapidly. For a feed of 5
percent organics by weight, the heat of combustion is sufficient to
raise the oxidizer effluent to at least 550 °C.
3. The effluent from the oxidizer is fed to a salt and sediment separa-
tor, where inorganics and sediments originally present in the feed are
removed as a solid slurry. At 500 °C and above, the solubility of
inorganics in SCW is extremely low.
4. A portion of the superheated SCW is recycled to the SCW oxidizer by a
high temperature, high pressure pump. This operation provides for
sufficient heating of the feed to bring the oxidizer influent to
supercritical conditions.
5. The remainder of the superheated SCW (with some CC^) is used to
preheat the incoming soil slurry.
As a waste destruction process, the Modar concept has several advantages.
The chemical reactions that occur are carried out in a closed system, making
it possible to maintain total physical control of waste materials from stor-
age, through the oxidation process, to the eventual discharge of the products
of combustion and any associated wastes.
,, - *' -
In addition, bench-scale results indicate essentially complete destruction
of chemically stable materials (such as PCBs) at projected costs that are well
within those currently associated with hazardous waste operations. The proc-
ess can be adapted to a wide range of feed mixtures and scales of operation.
Skid-mounted, transportable systems are being designed as well as larger scale
stationary units.
A liquid PCB waste treated by SCW oxidation at the CECOS International
facility in Niagara Falls, New York, under permits, showed > 99.995 percent
complete oxidation (Modar 1985). This percent oxidation would have been
greater if the methods of analysis could have detected lower concentrations.
The analytical detection limits for the effluent were < 0.1 ppb in the liquid
23
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and < 4.8 ug/SCM in the gas effluent. Process tests with feeds at higher
concentrations, and lower effluent detection limits have shown 99.9999 percent
oxidation (e.g. dioxin). The company plans to commercialize the process in
1986 for treatment of liquid PCB.
Bench-scale tests of dioxin-contaminated soils have shown reduction to
background levels. The process is continuous, and the primary problems in its
development for treatment of soils are the selection of pumps for slurries (20
to 40 percent solids) and the need for supplemental fuel sources to maintain
heat input when trace concentrations are being treated.
The Modar System has been tested for soils, and major problems in handling
this type of process feed have been identified. The components would be con-
structed from corrosion-resistant, high-nickel alloys. Projected costs of
treatment alone are $184 to $554/m3 of PCB-contaminated sediment. Dredging
would be required, as well as transport for treatment and redeposition of
treated sediments. The overall cost estimate is thus:
Cost. $/m3 = ($20 dredging) + ($13 - $126 transportation)
* ($184 - $554 treatment) + ($33 deposition)
= $250 - $733/m3.
5.1.2 Nucleophilic Substitution
5.1.2.1 Principles—
Nucleophilic (electron-donating) substitution removes chlorine from aro-
matic compounds by two mechanisms, the intermediate complex mechanism and the
benzyne mechanism (March 1986). The intermediate complex mechanism consists
of the following two steps, with the first usually rate-determining:
Fast
-------
The resonance hybrid formed in the first reaction is represented by the
structures within the brackets. These are shown in an alternative representa-
tion for reaction 2. The overall reaction rate is increased by the presence
of activating groups (e.g., NO. N02) on the molecule.
The benzyne mechanisms occur on aryl halides such as PCBs, which require
stronger bases than normally used because they lack activity groups on the
molecule:
+ NH;
H
IMH,
If the aryl halide contains two ortho substituents, this mechanism cannot
occur.
Nucleophilic substitution using alkali metal hydroxides in poly (ethylene
glycol) [PEG], or poly (ethylene glycol methyl ether) [PEGM] (Brunelli et al.
1985) has been shown to remove chlorine from PCBs. Chlorine removal probably
involves alkoxide reaction, as illustrated by the following mechanism:
ArCln + ROK -» ArCln_! - OR + KC1
Chlorinated Potassium .. „„;, ...
. . + , ,. . -» PEG ether
aromatic glycollate
The partially dechlorinated, water-soluble reaction product may continue to
undergo dechlorination. depending on the reaction conditions. .
-------
The application of alkali-PEG (APEG) reagent to decontamination of
PCB-contaminated soils and sediments is. under investigation at EPA. The reac-
tion proceeds rapidly at 70 to 100 °C. The degree of dechlorination can be
controlled by modification of the reaction conditions. The KOH-PEG reagent
tolerates a fair percentage of water. PCBs and other halogenated molecules
are soluble in the reagent. Extraction of the PCBs from the soil is accom-
plished by adding a phase transfer agent to the reagent.
The number of nucleophiles that have been investigated for PCB dechlorina-
tion is small, relative to the number identified as affecting the substitution
reaction. Although it is not possible to construct a nucleophilicity rank
order that is invariant because different substrates and different conditions
lead to different orders, an overall approximate order is: NH2~ > PlvjC" >
PhNH~ > ArS~ > R0~ > R2NH > ArO~ > OH~ > ArNH2 > NH3 > I~ > Br~ (March, 1968).
Nucleophilicity is generally dependent on base strength, and it increases from
atom to atom down a column of the periodic table.
Nucleophilic substitution by alkali reagents such as sodium naphthalide
has been used extensively for dechlorination of PCBs in transformer oils. The
reaction is fast, but it is not tolerant of water.
i
5.1.2.2 KPEG Terraclean-Cl Process—
5.1.2.2.1 Description—The KPEG treatment process is the subject of an
in-house study at the Hazardous Waste Engineering Research Laboratory, of
preliminary work on a conceptual treatment at New York University based on the
high absorptive affinity of soils for PCBs, and of a process identified by
Galson Research Corporation as Terraclean-Cl. Evaluation of this process is
based upon data for the Terraclean-Cl version. A patent has been granted on
this process and will be published in mid-1986.
The Terraclean-Cl process involves the chemical dehalogenation of PCBs
under mild conditions. This is achieved by mixing the s'oil with an equal
volume of hot (150 °C) reagent in a rotating mixer such as a converted cement
mixer. - Water coming in with the soil is volatilized and recovered for later
use in the process. The reagent consists of a mixture of polyglycols and
capped polyglycols (PEG and PEGM), potassium hydroxide (KOH), and dimethyl
26
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sulfoxide (OMSO). The exact formulation of the reagent is varied according to
the specific soil and contaminant combination. The DMSO does not take part in
the reaction but acts as a catalyst and phase transfer agent to extract the
PCBs from the soil.
At the end of the reaction, usually 30 to 120 min. the bulk of the reagent
(>80 percent in field tests) is decanted from the soil. A small part of the
reagent remains on the soil, along with some of the dechlorinated reaction
products. The residual reagent and dechlorinated by-products are removed from
the soil by mixing the soil with an equal volume of water and decanting the
water. This washing is done two or three times and provides >99 percent over-
all recovery of reagent. The washwater from the last wash is passed through a
bed of activated carbon, which preferentially removes the dehalogenated prod-
ucts. The contaminated carbon is burned in a PCB incinerator. The overall
process, including recycle streams, is shown in Figure 2.
The partially dechlorinated PCB continues to dechlorinate, with >98 per-
cent of the chlorine associated with the PCB being recovered as KC1 under some
conditions. The DMSO does not take part in the reaction but acts as a cata-
lyst and phase transfer agent, increasing both the rate of reaction and the
rate of transport of PCB from the soil into the reagent.
Process kinetics for the Terraclean-CL process are affected by:
• Soil carbon content
• Soil particle size distribution
• PCB isomer distribution
• Water content of the soil
• Reaction temperature
• Reagent formulation.' . ~
', . •
High carbon soils give the slowest rates of reaction, with reaction times
as long as 2 h for reduction to <1 ppm PCB. Very fine soils with poor perco-
lation characteristics take longer to drain,-although the constant mixing used
during the washing steps reduces the time -required for draining the soil. The
rate of reaction for different PCB isomers is inversely proportional to their"""
27
-------
ro PCB
00 soil
Water
Reagent
Makeup
Water_
Vapor"
Condensor
r if
Reaction
(150 C)
Decant
Reagent
Heater
First
Soil
Wash
Second
Soil
Wash
Byproduct Removal
by Activated Carbon
T
Byproduct Adsorbed
on Activated
Carbon
Fresh
Water
Non-PCB
Soil Reagent
(trace)
Figure 2. Schematic of kPEG process.
-------
biodegradability, with the most heavily chlorinated isomers being the easiest
to react. At reaction temperatures below 100 "C, the water content of the
soil affects the rate of reaction. At reaction temperatures around 150 °C
(the preferred reaction temperature)," the initial soil water content is
irrelevant because the water rapidly volatilizes. Dioxin-contaminated soils
with initial water contents as high as 40 percent have been decontaminated
rapidly using this process. The rate of reaction increases with temperature
up to around 200 °C. where degradation and volatilization of reagents becomes
a problem.
A variety of successful reagent formulations have been used in this
process, each employing a different mixture of glycol/sulfoxide/hydroxide.
Laboratory experience indicates that the optimum reagent formulation varies
somewhat for different soils and patterns of contamination. At present, it is
necessary to determine experimentally the optimum reagent formulation for each
soil.
Under preferred reaction conditions, PCBs are reduced from 500 ppm to
<0.1 ppm in 0.5 to 2.0 h. Residual PCB concentrations in treated soils can be
<0.04 ppm as determined by solvent extraction/gas chromatography. The current
laboratory and field test data support a fairly good mass balance (+: 2 to 5
percent).••...
The Terraclean-CL process can be handled in several sizes of mobile
(trailer-mounted) equipu,^.., >. por .use in cleaning Hudson River sediments, it
is assumed that a; total of 153.000 m3 are to —Qslted over a !_yr period.
At a 75-percent utilization rate,....this would require a no«maa. ~-____ ^f
570 m3 per day. This could be supplied by a set of five treatment modulesT
Each module would consist of three reactor trailers, each with a capacity of
14 m3, served by a.single utility trailer and associated tank trailers:'
Boiler
---.Tanker .
Tanker
Tanker
<2>
-±
Reactor
^ -Reactor
Reactor ~~""~J
Utility Trailer
29
-------
Process flow rates for a single 14-m3 capacity reactor trailer in this
size system are shown in the flow sheet in Figure 3. Flow rates would be the
same for each reactor trailer. This balance assumes incoming and outgoing
soil at 40 percent moisture and 1 percent reagent loss. The actual values for
items will vary as a function of the soil characteristics.
The boiler sizing assumes a nominal reaction temperature of 150 °C. Tem-
peratures in the range of 120 to 180 °C are acceptable. Much lower tempera-
tures may extend the reaction time unnecessarily, and higher temperatures may
cause reagent degradation or pressure buildup.
_ :*r
Because of the closed nature of the process, no pollution control equip- r
ment is likely to be required. The major potential problem is slow draining
time caused by a buildup of fines on the reactor filter screens. This should
be handled by the constant mixing of the reactor contents during the reaction
and washing steps. The mixing should prevent buildup of an impervious layer
during processing. This assumption is to be tested shortly using a pilot-
plant unit to be built in mid-1986.
Laboratory-scale trials of this process have mostly processed soils con-
taminated with 1,2.3,4- or 2,3,7.8-tetrachloro-p-dibenzo dioxin. The small
amount of PCB work in this area has been done as a preliminary to the dioxin
studies. Dioxin levels in treated soil have been reduced to jf 0 - .o*-"PP'b , al-
though the usual detection limit has been in _t h-. -.-"•-«*'• 1 .0 PPb. Of the four
or five PCB soils tested to .d»t— ~"cn has been reduced to
-------
Reagent Makeup
300#/Batch
PCS Soil
32,400*
21.600*
.17* PCB
\
Reagent T
30,000#/B
i
•18yd
Soil —
Water
I
\
»•
ank
i -
Water Vap
30.000 #/£
Heater
30,000,000
Btu/Batch
React PCBs/
Decant Reagent
Phase
or
latch—
— »»
Condensor •
Wash Tank 2
30,000#/Batch
•'\
f
First Water
Wash of Soil
.—
f
Wash Tank 1
30,000#/Batch
\
Second
"•*" Washc
Bipherr
174
r
Water
»f Soil
/Is Removal
match
Non-PCB Soil
32,400# Soil
21,600#Water
300# Reagent
Figure 3. Schematic of scaled-up KPEG process.
-------
Material
PCB soil
2-Methoxyethoxyethanol
Dimethyl sulfoxide
Potassium hydroxide
Water
Reaction temperature (°C)
Reaction time (h)
Initial average PCB concentration (ppm)
Final average PCB concentration (ppm)
Weight of materials, Ib
Run 8 Run 13
87
39.25
37.75
20
40
100
2
25.4
0.9
97
44
45
20
20
100
8
21 .8
0.8
This pair of runs demonstrated that temperatures as low as 100 °C were
adequate to reduce PCB levels to <1 ppm and that reaction time was not a major
factor in the overall degree of removal.
The apparatus used for decontamination of PCB-contaminated soils is shown
in Figure 4. The apparatus consists of six items:
DRUM PUMP
RESERVOIR VALVE
REAGENT DR WASH
WATER DRUM
REACTION DRUM
ON DRUM ROCKER
VENT
CARBON
FILTER DRUM
Figure 4. Schematic of dioxin-treatment system.
A two-section reaction drum with a section for soil on top of a reser-
voir for liquids. The two sections are separated by a steel plate with
a valve in it. A drum pump.is fitted into the lower section (liquid
reservoir), and there are two taps into the top se'ction. One tap
allows liquids to be pumped into the drum, and the other tap is a vent.
In addition, a thermometer well fitted with a bimetallic thermometer
(not shown) is part of the top of the drum. A drum heater is wrapped
around the drum, followed by Fiberglas insulation.
A steel rocker, used to agitate the soil/reagent mixture by moving the
drum and contents from side to side.
32
-------
• A carbon filter drum attached to the vent from the reaction drum.
• Two drums used for washwater.
. One reagent recycle drum.
• A source of freshwater, either a drum or hose.
The test protocol used for testing the process consisted of the following
tasks:
1. Obtain contaminated soil in 55-gal drums. Sample and analyze to
determine initial PCB concentration.
2. Weigh approximately 45.4 kg (100 Ib) of contaminated soil into a
reaction drum, with the reaction drum resting on a scale. Wet the
soil prior to transfer if dust generation is likely to be a problem.
Sample drum contents and place lid on reaction drum.
3. Place heat tape and insulation around the reaction drum.
4. Attach the vent line to reaction drum and connect to carbon filter
drum.
5. Place the reaction drum on the rocker.
6. Weigh reagents into the reaction drum from reagent drums using drum
pumps on each reagent drum.
7. Turn on power to the heat tape and agitator and heat the reaction
drum and contents to 150 °C, mixing during heating.
8. Allow reaction to proceed for the required time with mixing.
9. Turn off power to the heat tape,and allow reaction drum contents to
cool. Continue mixing during cooldown.
10. Open valve in reaction drum (see Figure 4) and allow reagent to drain
into reaction drum reservoir. Continue mixing during cooldown.
11. Weigh reagent out of reaction drum reservoir into reagent recycle
drum. Sample reagent.
12. Pump, 45.4 kg (100 Ib) water, from water supply drum into the. reaction
drum and' mix.
13. Allow water to drain into reservoir.
14. Pump water into wash drum 1. Sample water.
15. Pump 45.4 kg (100 Ib) water from water supply drum into the reaction
drum and mix.
33
-------
16. Allow water to drain into reservoir and pump into wash drum 2.
Sample water.
17. Open reaction drum, mix and sample soil. Seal drum for storage,
pending analysis of soil.
5.1.2.2.2 Vent from reaction drum—The purpose of the vent on the reac-
tion drum Is to allow water vapor to escape. The carbon drum filter prevents
the escape of any reagent or PCB vapors into the atmosphere, although analysis
of vent streams in multiple laboratory samples did not show any cases where
PCB vapors were vented under processing conditions.
5.1.2.2.3 Efficiency—The efficiency of the process for PCB removal from
the soil varies with reaction temperature and reagent formulation. PCB re-
moval to less than 1 ppm is routinely achieved, and PCB removal to <0.04 ppm
has been demonstrated. Dioxin removal to the part per trillion (ppt) level
has been demonstrated in the laboratory, and it is reasonable to assume that
PCB reductions to that level are possible, although at present it would be
extremely difficult to analyze soil samples at such a low level.
5.1.2.2.4 Reaction products—Analytical methods applied to the soil sam-
ples following reaction has been set up to identify any partially reacted PCB
reaction products as PCBs. It is not known if there are any residual, totally
dechlorinated PCBs in the soil, although it seems probable that these materi-
als would be readily removed by the water wash. The water wash is passed
through activated carbon to remove the biphenyl materials (see flow sheet) and
the saturated carbon burned as a PCB waste. This practice has been devised as
an alternative to proving the innocuous nature of the substituted biphenyls.
Initial testing indicates that the substituted biphenyl products have an LUso
(oral-rate) >5 g/kg, indicating a very low degree of toxicity. Tests of the
toxicity of the dioxin reaction products are under way at EPA. with initial
tests indicating that the reaction products are not mutagenic (Ames test).
Tests of chlorobenzene reaction products indicate that the reaction products
do not bioaccumulate in fish.
5.1.2.2.5 Conditions/limitations—Conditions for successful processing of
PCB soils to <1 ppm require reaction temperatures on the order of 100 to
150 °C and reaction times of 0.5 to 2 h. Total cycle times of 4 to 8 h are
3U
-------
probable. Reagent is applied to the soil in a 1:1 ratio (dry basis) followed
by reaction and reagent recovery. Reagent recoveries in excess of 99 percent
have been obtained in PCB field testing. Initial soil water concentrations
are not relevant to the process, except as it affects process economics
because the water is volatilized during the heating step.
5.1.2.2.6 Energy usage- Energy requirements for the process are largely
involved with heating moist sediments to 150 °C and removing the water by
volatilization. For example, a sediment containing 40 percent water would
require 4,818,000 kJ of energy per cubic meter, calculated as follows:
Mass of sediment 1680 kg
Mass of Water
in sediment 1119.7 kg
in wash return 659.4 kg
Total 1779.1 kg
Mass of Reagents 1555 kg
Temperature rise
volatilized water 100-20 = 80 °C
soil and reagents 150-20 = 130 °C
kJ required ,
to heat water: 1779 x 4.18 x 80 = 594,898
to vaporize water: 1555 x 2,326 = 3,616.930
to heat sediment: 1680 x 0.84 x 130 = 183.456
to heat reagent: 1555 x 2.09 x 130 = 422.494
Total kJ 4.817,778
The cost of energy, assuming a cost of S0.26/L #2 fuel oil and an energy value
of 37,730 kJ/L, would be approximately $33.20/m3 of soil.
Full-scale (730 m3/day) processing of Hudson River sediments could begin
in 21 to 24 months. The events required include:
• Design full-scale (7-trailer) unit * 6 months
* Construct first full-scale unit 6 months
• Test full-scale unit 3 months
• Construct additional units 6 months
35
-------
5.1.2.2.7 Cost estimate—This process has not been scaled up to the size -,
necessary for application to a site of this size. However, some initial cost
estimates have been made and may be used as order of magnitude values.
Capital costs were estimated assuming a set of six treatment modules com-
pletely amortized over the life of the project. Costs for each module are
comprised of the following items:
• Utility trailer $600.000
• Reactor trailers (3) $800,000
• Tank trailers (3) $200,000
Total for each module $1,600,000 ^
Total for modules $9,600,000
Capital cost. $/m3 $25.11
This cost assumes an 8-h cycle time. If a 4-h cycle time can be achieved,
the capital cost would be $4,800,000 or $12.56/m3 of soil processed.
Other processing costs include reagents, energy, labor, and maintenance.
These are estimated below:
Reagent costs—At a usage rate of 1555 kg/m3 of soil and an average
cost of $1.65/kg/ a 1 percent loss equals $25.66 =
1,423 x 0.01 x $1.65 = $25.66/m3 soil
• Energy costs—At 40 percent incoming moisture = $33.20/m3
(see previous calculation)
• Maintenance costs—Assume 10 percent of capital costs = $1.26 -
$2.51/m3
• Labor costs—Assume, for each module:
9 operators § $300/day $2,700
3 backhoe operators @ $350/day $1.050
3 chemists at $400/day $1,200
1 site manager § $550/day $550
Total $5.500/24-h day
Processing rate = 124 to 247 p»3/24-h day
(4- or 8-h cycle)
Manpower costs = $22 to $44/ra3.
36
-------
This manpower cost estimate assumes that the sediments are moved from a
storage area to the reactor. However, manpower costs would be reduced and the
holding area eliminated if the sediments were moved by hydraulic dredge
directly into the reactor, with the reactor serving to handle the gross de-
watering of the sediments. Soil and water would be pumped to the reactor,
which removes most of the water, retaining the bulk of the soil. Fine sedi-
ment particles are removed by a filter press, which is emptied periodically
into a reactor. This approach would reduce the land area required and the
labor involved, but it requires a closer fit between dredging capacity and
reactor cycle time. Potential emissions of PCBs from holding areas would be
eliminated, which may be a significant consideration:
Waste disposal - 2 kg activated carbon/m3 soil at $1.10/kg = $2.20.
The total cost of application of the treatment process is estimated as
follows:
Cost item Cost. $/m3
: 4-h cycle 8-h cycle
Capital 12.56 25.11
Reagent 25.66 25.66
Energy 33.20 33.20
Maintenance 1.26 2.51
Labor 22.00 44.00
Water disposal 2.20 2.20
Subtotal 96.88 132.68
Profit/contingency (50 percent) 48.44 66.34
Total 145.32 199.02
These costs do not Include dredging or permitting costs. With dredging
costs of $20/m3. transportation costs of $13 to $126/m3. and final placement
costs of $33/m3, total costs in the range of $211 to $378/m3 are anticipated.
Permitting costs are a separate item and would depend on the degree of cooper-
ation given by the various regulatory bodies involved. However, the total
costs are not highly sensitive to this item because permitting costs of
$5.000,000 would only add $5/m3 to the costs of processing.
37
-------
5.1.3 Radiant Energy-Ultraviolet Light
5.1.3.1 Principles—
Ultraviolet (UV) radiation may drive chemical reactions in PCBs. The
structure of the products of UV radiation alone are not well defined (Sworzen
and Ackerman 1982). The primary reaction at wavelengths greater than 290 nm
is stepwise dechlorination. Photolysis experiments in methanol at 298 to 313
K for 10 to 15 h showed that HC1 was evolved. The products contained in the
methanol solution consisted of dechlorinated PCB and certain methanol substi-
tution products. The amount of methoxylated products did not exceed 5 percent
of the total amount of products formed.
UV light energy, combined with a reducing environment, has been used to
dechlorinate PCBs essentially completely in 1.5 to 2 h (Kitchens et al. 1982,
1984). Because the photochemical reaction is initiated by the absorption of
light energy, the irradiation wavelength must match the absorption band asso-
ciated with the chemical bond of interest in the molecule and the solvent must.
not absorb significantly at the irradiation wavelength. For PCBs, low-
pressure mercury lamps that emit approximately 95 percent of their energy at
2,537 A provide adequate irradiation.
Suitable solvents include water, alcohols, and hydrocarbons. However,
these have very different effects on the process efficiency and mechanism. In
heavy hydrocarbons, the dominant PCB reaction is the polymerization of the
biphenyl radicals to yield polyphenylenes. In basic alcohol solutions, a
stepwise dechlorination of the molecule occurs. This reaction occurs via the
triplet state, and the reaction rate is dependent on the lifetime of that
state. The hydrogen for the hydrodehalogenation initially comes from the
solvent. In alcohol solutions, sparged hydrogen gas increases the reaction
rate by removing triplet quenchers from the solution by combination with the
solvent free radicals formed. In addition to the hydrogen, small amounts of
sodium hydroxide are added to the alcoholic solution as a chlorine scavenger.
These photochemical reaction conditions lead to a rapid, highly control-
lable destruction of the PCBs, yielding only biphenyl and sodium chloride as
the final products. Oxygenated derivatives, chlorinated dibenzofurans. or
38
-------
chlorinated dioxins have never been observed in the gas chromatographs or the
mass spectra of the intermediates or products in the LARC degradation of PCBs.
5.1.3.2 LARC Process—
The LARC process (Light Activated Reduction of Chemicals, U.S. Patent
4.144,152) uses UV light and an optimized reducing environment to dehalogenate
various chlorinated compounds extracted from soils.
Studies were performed to determine the extraction efficiency from soil of
Aroclor 1260 using isopropanol as the extraction solvent (Kitchens et al.
1984). Isopropanol was chosen because it is a good LARC solvent, dissolves
PCBs readily, and is relatively inexpensive.
For the initial extraction studies, a clay soil was used (2.0 percent
organic matter; pH 5.6; Ca, Mg, P, and K levels were 660. 77, 56. and
20 mg/kg, respectively). Air-dried soil samples were spiked with Aroclor 1260
in acetone and thoroughly mixed; the acetone then was allowed to evaporate in
a hood. Random subsamples of the soils were taken and Soxhlet extracted using
a mixture of 50 percent acetone and 50 percent hexane. The extracts were
diluted to the appropriate range and analyzed by gas chromatography.
Weighed amounts of dried, spiked soils were placed in four 1-L beakers
(two for each chemical). Added to each of the four spiked soil samples were
100 raL of distilled water; these samples were thoroughly mixed to yield wet
soils containing approximately 25 percent water. Then, 500 raL of isopropanol
was added to each beaker and the mixtures stirred for 10 min. The liquid from
each beaker was decanted and the volume measured. This procedure was repeated
once. A portion of each extract was taken, diluted, and chromatographed as
described above to determine the amount of halogenated organics removed from
the soil in each extraction step. The soils then were air-dried, and a random
sample was taken from each, Soxhlet extracted, and analyzed as above to deter-
mine the amount of Aroclor 1260 remaining in the soils.
One set of extractions of each chlorinated organic was combined and sub-
jected to LARC using the single-lamp batch recirculation reactor shown in
Figure 5. The reaction rates in this single-lamp reactor are significantly
lower than in a multiple lamp, high-light-density reactor. However, only
39
-------
H2
Vent
X
Feed
Supply
Liquid Level »•
Gauge
Jf Pump
CE)
t^s*
Gauge
0-200 psi
Circ.
Pump
J
\
Sample
Port
Power Supply
and Ballast
.6
. t
o*
* •
•>
ea
*
;o
o.
•i^m
1 Sight Glass
•« SST tube
housing
and Sleeve
> Gas Sparger
~j Sight Glass
Figure 5. Schematic of single-lamp LARC reactor.
-------
800 mL of solution is required for operation as compared to 30 gal for the
64-lamp pilot unit. Because the scaling factors between the two reactors were
known, this single-lamp reactor was a convenient unit for evaluating the deg-
radation rates under differing conditions.
Sodium hydroxide pellets were added to each set of extracts to form
2-percent solutions, and a portion of each solution was analyzed to determine
the initial Aroclor 1260 concentration. The reaction was started by placing
the solution into the reactor. The hydrogen gas then was turned on and allow-
ed to purge the reaction mixture for 5 min. Then the UV light was turned on.
Samples (10 mL) were drawn from the reactor after 20, 40, 60, 90, 120, and 180
minutes so that the degradation reaction could be followed and the reaction
rate.determined.
PCB analyses for the degradation were conducted using a Varian 3700 gas
chromatograph and an autosampler with a Hewlett-Packard 5880 computer con-
troller/integrator.
The results for the extraction of Aroclor 1260 from soil are. summarized in
Table 3. For dry soil, the Aroclor was extracted with an efficiency of 70 to
75 percent per stage and an overall two-stage efficiency of 92 percent. The
single-stage extraction efficiency from wet soil was slightly lower than from
dry soil (55 to 60 percent). Overall extraction efficiency based on the
amount remaining in the soil was 90 percent. At least five stages of extrac-
tion would be required to achieve the goals of residual concentrations at
background levels. The ratio of solvent to soil also may have to be increased
from the 1.2/1.0 (wt/wt) used in these experiments.
The results of the LARC degradation of Aroclor 1260 in the isopropanol
soil extracts are shown in Figure 6. Degradation proceeded rapidly, even in
the presence of particulates with a pseudo first-order rate constant of
0.052/min. This was calculated based on the disappearance of all chlorinated
species. In a larger reactor with a greater light density, the degradation
rates can be expected to be 2 to 2.5 times those of the single-lamp reactor.
-------
TABLE 3. EXTRACTION DATA FOR CHLORINATED ORGANICS FROM SOIL
Aroclor 1260
Dry soil Wet soil
Initial concentration (rag/kg) 487 486
Weight of soil (g) 330 330
Amount removed from soil in
first extraction (mg/kg) 337 268
Solvent recovered from first
extraction (mL) 320 360
Amount recovered from soil in
second extraction (mL) 113 131
Solvent recovered from second
extraction (mL) 420 410
Final concentration in extracted
soil (mg/kg) 38 50
Overall extraction efficiency (%) 92 90
-------
100
90
20 40 60 90 120
Residence Time (minutes)
Figure 6. LARC degradation of Aroclor 1260 in basic isopropanol.
-------
5.1.3.2.1 Efficiency--The laboratory tests indicate that PCBs can be
extracted efficiently from both wet and dry soil using a solvent such as iso-
propanol (>99 percent). The PCBs in the extract can be successfully degraded
by the LARC process. Any process must be capable of handling extremes in
concentrations of PCBs and still maintain preset criteria for their removal
from the soil and destruction.
5.1.3.2.2 Scale-up—The data from laboratory tests were used to design a
mobile unit that can clean up spills of chlorinated organics from soils. A
process schematic is shown in Figure 7. The equipment would be mounted in a
standard trailer and consist of two extraction units to remove the chlorinated
organics from the soil. After extraction, the soil would be vacuum-stripped
to remove and recover residual solvent. The soil could then be returned to
any suitable site. The extraction solvent would be sent to a still where the
solvent would be recovered for reuse in the extractors and the chlorinated
organics concentrated. Enough concentrate will be produced to provide feed
for the LARC reactors on a continuous 24-h basis. Thus, the concentration
entering the LARC units can be tightly controlled even though the concentra-
tion in the soil varied dramatically. This process design provides the flexi-
bility to treat any type of soil at varying concentrations of chlorinated
organics and still maintain optimum rates of reaction in the reactor. Costs
for the removal of PCBs from soil and destruction by the LARC process are
dependent on their average concentration in the soil. In most soils, high
concentrations may be found close to the site of contamination. Once out of
the immediate area, the concentration will drop off rapidly. However, if
leaching has occurred, large areas contaminated at between 1 and 500 ppm can
be expected.
5.1.3.2.3 Cost—The cost of treatment using this process has been esti-
mated using an average concentration in the soil of 1,500 ppm (Kitchens et al.
1984). Cost items include daily operation, labor, analytical, travel, per
diem, and profit. These total approximately $157/m3 of soil. Adding costs of
dredging, transportation, and placement gives a cost range of $223 to $336/m3.
-------
\^
V«l«M
' Dry Sediment Product
•1
(III!
tun
M*UIM
TMk
-OH
-D-O-I
N«ON W««t»
M*«lMi n»t»*r»
Figure 7. Schematic of LARC mobile unit for destruction of PCB's in soil.
-------
5.1.4 Pyrolysis
5.1.4.1 Principle—
Pyrolysis is a thermal rupture of the chemical bonds of a molecule that
destroys it without oxidation. The energy requirements vary with the material
being processed. The use of pyrolysis requires the adoption of process
designs that provide for transport of material that can melt, char, or become
sticky during passage through a reactor. The design must provide for effi-
cient heat transfer to the material so that it can be heated to 2,000 to
2,300 °C. Pollution controls are required to remove particulates and toxic
components from exit gases. Feeds to pyrolysis units must usually be pre-
dried.
Compared to chemical processes, pyrolysis processes have higher energy
requirements.
5.1.4.2 Advanced Electric Reactor, J. M. Huber Corporation—
The advanced electric reactor (AER) is a thermal treatment process. Pre-
treatment of the feed material is required. It must be dried to a moisture
content of less than 3 percent and ground to 35 mesh particle size.
The process is patented, and all patents are owned by the J. M. Huber
Corporation. The process is fully permitted under the Toxic Substance Control
Act (TSCA) in EPA Region VI for the destruction of PCBs (permit received in
May 1984}.
As described in the trial burn report (J. M. Huber, October 31, 1983), the
treatment process is based on a high-temperature fluid-wall reactor
(Figure 8). The reactor heats organic compounds rapidly to temperatures in
the range of 2,200 "C using intense thermal radiation in the near infrared.
The reactants (in this case, nonliquid PCBs) are isolated from the reactor
core walls by a gaseous blanket of nitrogen flowing radially inward through
the porous core walls. Carbon electrodes are heated and. in turn, heat the
reactor core to incandescence so that heat transfer is accomplished by radi-
ative coupling from the core to the feed materials. The only feed streams to
the reactor are the solid waste containing PCBs and the blanket gas (nitro-
gen). PCBs are destroyed by pyrolysis rather than oxidation. Therefore.
16
-------
1. Expansion Bellows
Z Power Feedthrough
Cooling Manifold
4. Power
Feedthrough
Assembly
6. End Plate
8. Electrode
10. Radiation
Heat Shield
11. Heat Shield
Insulator
12. Cooling Jacket
3. Power Clamp
5. Radiation Deflector
7. Electrode Connector
9. Porous Core
13. Radiometer Port
14. Blanket Gas Inlet
(typical)
t Figure 8. Vertical cross section of the Advanced Electric Reactor.
-------
typical products produced by incineration such as carbon monoxide, carbon
dioxide, and oxides of nitrogen are not formed in significant concentrations.
The principal products of soil-borne PCB destruction are H2, C12. HCl, ele-
mental carbon, and a granular free-flowing solid-derived waste.
Figure 9 shows a simplified process diagram. The solid feed stream is
introduced at the top of the reactor by a metered screw feeder connecting the
air-tight feed hopper to the reactor. Nitrogen is introduced primarily at two
points in the reactor annulus formed by the external Containing vessel and the
porous graphite core to create the fluid wall.
Small nitrogen streams are used to sweep sight glasses, prevent oxygen
intrusion at the electrode ports, and similar nonprocess uses. Nitrogen flow
is monitored by calibrated orifices in each feed line. The solid feed passes
through the reactor where pyrolysis occurs. After leaving the reactor, the
product gas and waste solids pass through two post-reactor treatment zones
(PRTZ). The first PRTZ is an insulated vessel that provides additional
high-temperature (-1,095 *C) residence time (~5 s), and the second PRTZ is
water-cooled. It also provides additional residence time (-10 s), but it
primarily cools the gas to less than 538 °C prior to downstream particulate
cleanup.
The product gas then enters a baghouse for fine particle removal followed
by an aqueous caustic scrubber for chlorine removal. Any residual organics
and chlorine are removed by passing the product gas through two banks in
series of five parallel activated carbon beds just upstream of the emissions
stack. The organic-, particulate-, and chlorine-free product gas, composed
almost entirely of nitrogen, is then emitted to the atmosphere through the
process stack.
Solids exiting the PRTZ are collected in a solids bin that is sealed to
the atmosphere. Additional solids in the product gas are removed by a cyclone
and routed back to the solids bin. The solids collected'in the solids bin are
removed by plant personnel after each test or pair of tests.
5.1.4.2.1 Process operating parameters—The trial burn consisted of four
tests conducted on 3 days. In all cases Aroclor 1260 was mixed with sand to
U8
-------
POST
REACTOR
ZONES
AIRTIGHT
HOPPER
FOR FEED
METEREO
SCREW FEEEOER
ELECTRIC
REACTOR
ACTIVATED
CARBON BEOS
MAKEUP WATER
AND N«OH
STACK
CAUSTIC
SCRUBBER
(J. M. Huber).
Figure 9. Schematic of Advanced Electric Reactor process.
149
-------
form a solid waste feed containing approximately 3,000 ppm PCBs. Carbon black
was also mixed with the feedstock at approximately a 6.25:1 ratio to the PCB
oil. This was equivalent to about 2.5 percent of the total feed mass. Carbon
black functioned to enhance radiant energy transfer to the feedstock and to
reduce coagulation of the sand particles.
There were no major differences in the process parameters for the four
test periods. Feed rates were 7 kg/rain to 7.2 kg/min with total feed masses
ranging from approximately 1,580 kg to 1.927 kg depending on test duration.
These feed rates were approximately halfway between the engineering design
feed rates for the pilot plant of 4.5 kg/min and 9 kg/min. The nitrogen flow
rate was held at 4 SCM/min for all test periods. Process temperature and
scrubber pH also were essentially constant for the duration of the trial burn.
Process maintenance during the burn included changing the scrubber liquid
after each test and emptying the baghouse filters.
5.1.4.2.2 Sampling methods—Sampling was performed using EPA reference
methods when available, in some cases with appropriate modifications.
5.1.4.2.3 Removal by scrubber and carbon beds—Chloride removal in the
product gas was accomplished by using a caustic scrubber installed prior to
charcoal bed installation. Removal efficiencies based on scrubber inlet and
stack concentrations indicate greater than 99.999 percent removal of chloride.
This high efficiency may reflect chloride reacting with and/or being trapped
by the carbon beds in addition to the expected 90 to 99 percent removal by the
caustic scrubber.
5.1.4.2.4 Dechlorination of PCBs—Test data indicated that, in general,
the chlorine content in the Aroclor 1260 was accounted for by C12 and/or HC1
at the scrubber inlet. Because there are no other sources for chlorine in the
process except possible low levels of chlorine salts in the sand, it may be
concluded that the chlorine content in the PCB feed is being converted to free*
.chlorine in the reactor.
.5.1.4.2.5 Test results and conclusions—The major thrust of the sampling
and analytical effort carried out during the trial burn was the determination
50
-------
of PCB disposition in the process and PCB destruction and removal efficien-
cies. To accomplish these goals, PCB analyses (GC/MS) were performed for all
effluent and waste streams, the PCB feedstock, and the process gas at the
cyclone outlet. Other parameters that were measured included PCDDs and PCDFs
in the cyclone outlet, major gas composition NOX, chloride, participate load-
ing, volatile halogenated organic species in the stack and cyclone outlet, and
chloride at the caustic scrubber inlet.
Results for the two potential solid waste streams, treated sand and bag-
house filter catch, were in the range of 0.0005 Ug/g to 0.001 Ug/g (0.5 ppb to
1 ppb) and 0.024 Ug/g to 0.53 Ug/g (24 ppb to 530 ppb) PCB, respectively.
These values are all well below the 50 ug/g (50 ppm) lower limit set for
solids to be treated as hazardous wastes (40 CPR 761.60 Subpart D). These
data indicate that for PCBs both streams can be considered nonhazardous wastes
for disposal. The PCB concentration determined for the posttest charcoal was
0.001 ug/g (1 ppb) and was lower than that of the pretest sample.. Both values
closely approach detection limits. These'data indicate that for PCBs the
activated charcoal can be considered nonhazardous for disposal. However,
surrogate recoveries may be artificially high due to spiking of the extraction
thimble rather than the charcoal. Therefore, these data are not conclusive
because the actual recovery of PCBs from the charcoal may be lower than indi-
cated. .
The only liquid waste produced by the AER process was the scrubber liquid.
Although the results of the PCB analyses were variable, ranging from 0.29 ug/L
to 2.7 ug/L (0.29 ppb to 2.7 ppb), all determined concentrations were well
below the 50-rag/L (50-ppm) lower limit set for liquids to be treated as
hazardous wastes (40 CFR 761.60 Subpart 0). These data indicate that for PCBs
the scrubber liquid can be, considered nonhazardous. ;
Gas samples were taken at.the cyclone outlet and stack using modifications
of EPA Method 5. PCB concentrations ranged, from 4.1 ug/SCM to .21 Ug/SCM for
the cyclone outlet. Stack concentrations-were,approximately one to-.two orders
of magnitude lower, ranging from 0.03 ug/SCN to 0.30 ug/SCM. The high stack
blank value reflects interferences due.to overheating during sample prepara-
tion and represents the interferences in ions 292 and 326; Blank subtraction -
was not performed for determining destruction and removal efficiencies.
51
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5.1.4.2.6 PCB destruction and removal efficiencies—Destruction efficien-
cies (DE) for the AER reactor were determined by comparing PCB concentrations
at the cyclone outlet to calculated gas phase feed concentrations based on
solid feed concentrations and feed rates. Destruction and removal efficien-
cies (ORE) were determined by comparing PCB concentrations at the stack to
calculated gas-phase feed concentrations.
Two sets of DE's were computed: one based on weighed feed concentrations
(3,000 ppm in the solid feedstock) and the other on analyzed feed concentra-
tions. For both bases, the minimum DE was 99.9995 percent, with results
ranging from 99.9996 to 99.99995 percent based on weighed feed concentrations
(process data) and 99.9995 to 99.99995 percent based on analyzed feed concen-
trations. Two sets of DRE's were also calculated: one based on weighed feed
.concentrations and the other on analyzed feed concentrations. In all cases,
regardless of calculation method, the DRE's exceeded 99.99999 percent. Effi-
ciencies were at least an order of magnitude greater than the criterion estab-
lished for incinerators by TSCA (40 CFR 761.760 Subpart D).
5.1.4.2.7 Conditions required for successful processing--The AER requires
approximately 1,100 kWh per ton of soil treated. Operation of the required
pretreatment equipment (crushers, grinders, etc.) and other auxiliary items
use an additional 200 kWh per ton of soil.
The soil must be dry and sized to 35 mesh or smaller before it is fed to
the reactor. Moisture concentrations of 3 percent can typically be accommo-
dated. However, this may vary depending on the characteristics of the soil.
5.1.4.2.8 Cost—For very large volume cleanups, a cost estimate of
$412/ton ($763/m3) was supplied by J. M. Huber, strictly as a budgetary cost
figure and not as an absolute or a quotation. This amount does not include
the costs of dredging, transporting soil to the AER site, or facilities for
storage of dredged soil. It also does not provide for cost of landfill ing or
other disposal of the treated sediment.
The capital cost for construction and initial testing of a single
25.000-ton/year transportable AER is approximately $4 million, not including
-------
permits and trial burns. With six units, it would require approximately 3.5
years to treat 382.000 m3 of sediment.
Dredging would be required, also transport for treatment and redeposition
of treated sediments. The overall cost estimate is thus:
Cost, $/m3 = ($20 dredging) + ($13 - $126 transportation)
+ ($763 treatment) + ($33 deposition)
= $829 - $942/m3.
5.1.5 Thionation
Thionation introduces sulfur into an organic molecule to displace chlo-
rine. The possible use of sulfur reactions to degrade pollutants has not been
systematically exploited. Macallum (1984) showed that, at 150-170 °C. sulfur
and sodium carbonate react with p-dichlorobenzene, removing the chlorine to
form an insoluble polymer, sodium chloride, and carbon dioxide. Von Meyer
(1986) conducted limited tests of a mixture of dried loam soil sparged with
mixed dichlorobenzenes (DCBs). sodium carbonate, and sulfur. The dichloro-
benzenes were added as a 0.01 g/ml solution in acetone. Reaction was carried
out in a tilted 50tf-ml flask fitted with a condenser and sodium carbonate
trap. The trap was required to remove hydrogen sulfide gas evolved during the
reaction. The reactants were mixed periodically by rotating the flask a
quarter turn every two hours over the 9 hour reaction period. The temperature
ranged to 88 °C, and rose in the eighth hour to 260 °C when an exothermic
excursion followed evaluation of voiatiles formed from the sulfur. The re-
sults, based on analyses by thin layer chromatography and gas chromatography,
were as follows:
1.2 dichlorobenzene: 8.4 percent dechlorinated
3.4 percent volatilized
1.3 dichlorobenzene: . 90.8 percent, dechlorinated
3.4 percent volatilized
1.4 dichlorobenzene: 91 percent dechlorinated
1.4 percent volatilized. •
53
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This is the extent of Von Meyer's investigation of the application of *
thionation to contaminated soils. As part of his study. DCB's and three chlo-
rinated pesticides (Dieldrin, Lindane, and Heptachlor) were treated directly
with two reagents: sodium polysulfide in an ethylene glycol-water media, and
sulfur in ethylene glycol. With water present, the organics were all con-
sistently volatilized at the 108-114 °C reaction temperature. The sulfur-
ethylene glycol reagent degraded Dieldrin 99 percent and Lindane 90 percent.
Heptachlor was not tested with this reagent.
Thionation is in the early stages of investigation, and a process for
treatment of PCBs has not been sufficiently identified to permit further
evaluation.
5.2 PROCESSES BASED ON PHYSICAL TECHNOLOGIES
5.2.1 Extraction
5.2.1.1 Principles—
The term "extraction" is employed to cover not only liquid-liquid extrac-
tion but also leaching of solids with organic solvents. Extraction of PCBs
from a contaminated soil or sediment is emerging as a prerequisite for most
chemical processes. PCBs are first extracted using a suitable solvent, and
the obtained PCB solution is then subjected to one of the processes for
destruction of the PCBs. Proven solvents include kerosene, methanol, ethanol,
isopropanol, furfural, dimethyl formamide (DMF). dimethyl sulfoxide. ethylene
diamine, and Freon mixtures. Supercritical fluids such as carbon dioxide have
also been considered. Destruction of the dissolved PCBs is accomplished by a
chemical reagent such as APEG detoxification, or the PCBs are concentrated by
distillation or adsorption on carbon to give an RCRA waste that can be incin-
erated.
Water with and without 1 percent Tween 80 surfactant was shown to remove
PCBs by less than 50 percent. The additive increased removal from inorganic
soils but appeared to inhibit removal from organic soils (Scholz and
Milanowski 1984). The results in Table 4 show substantial residual amounts of
PCBs.
-------
TABLE 4. EXTRACTION OF PCBs FROM
SOILS. EFFECT OF TWEEN
Supernatant
Soil Dose Percent Residual Concentration
Soil Solvent (ppm PCB) removal (ppm PCB) (mg/L)
Inorganic Water 3,000 24.6 2,660
1* Tween 80 3,000 37.5 1.880
Organic Water 26.000 48.3 13.200
1% Tween 80 26,000 23.8 19,500
72
110
418
366
Hancher et al. ("Soilex" process, 1984) reported pilot plant data showing
an estimated 85 percent removal of PCBs from soils using a kerosene-water
mixture. The kerosene solubilized the PCBs and attendant other oils, and the
water helped break up the soil particles. The mixture ratio found to give the
most complete extraction of PCB was one part of soil to three parts of kero-
sene and three parts of water.
Adams et al. (1985) showed that the rate of liquid-liquid extraction of
PCBs from oils solution by APEG reagents could be substantially increased by
adding dimethyl sulfoxide (DMSO) or ethylene diamine to the hydroxide/PEG
phase. The reagent with DMSO reached <2 ppm PCB after 30 rain versus about
400 rain for the reagent without DNSO.
Weitzman (1985) reported that repeated washings of PCB-contaminated soils
with Freon-type solvents reduced the residual loading to <2 ppm. The soil
types tested were sand-clay mixtures and a dark loam. PCB loadings to
1.983 ppm were leached in an agitated extractor.
Chu and Vick (1985) reported that the use of isopropanol as a cosolvent
with DMF enhanced the reduction of PCBs by zinc in the presence of nickel
catalyst.
0. H. Materials (Caron. 1985) is using methanol to extract PCBs from pre-
dried contaminated soils in a Super fund cleanup project at Minden, West
Virginia. The soil is reduced to <25 ppm PCB and land-farmed. Further re-
-------
duction in PCB concentration could be achieved using more stages of extrac- =
tion. The PCBs in the extract are concentrated by adsorption on carbon, and
the spent carbon is incinerated as an RCRA waste.
5.2.1.2 Acurex Solvent Wash Process—
The Acurex process is based on solid/liquid extraction (Weitzraan 1984,
1985). A proprietary solvent is used, having been selected by comparisons of
adsorption isotherms and PCB diffusion rates into several fluids: pure
hexane. pure FC-113 (1,1,2-trichlorotrifluoroethane), a proprietary solvent
blend, and an FC-113/hexane blend. With the pure Freon and topsoil, the
equilibrium was favorable; however, it took up to 18 h for the system to reach
equilibrium. Other solvents and solvent combinations were found that reduced
the time to reach equilibrium to 30 to 40 min. a practical value.
Based on these fundamental studies, calculations showed that the ratio of
PCB concentrations yn and yn_i in the liquid leaving the nth and (n-l)th
washes, respectively (fresh liquid into each stage), was constant at 0.5:
0.5 = yn/yn-l •
This value proved to be reasonably independent of the type of soil being
cleaned and the PCB concentration in the soil itself. The wash liquid leaving
a wash would thus have a PCB concentration of approximately half that of the
preceding wash.
The process was pilot tested using the proprietary solvent to extract the
PCB from the soil. The PCB was then concentrated and the solvent reclaimed.
Final PCB concentrations of less than 2 ppm on the soil were achieved.
The system was designed and built in late 1984. It was operated using
non-PCB soils and shown to perform to design specifications. A permit to
operate the system with PCB-contaiuinated soil was obtained in February 1985.
Eight sets of tests were conducted, and these demonstrated that soils contain-
ing up to 1,983 ppm PCB were successfully treated to less than 2 ppm. In
addition to demonstrating this pilot- scale system, these tests provided
design data for construction of a full-scale proto-type soil-washing system.
The results of these tests are summarized in Table 5.
56
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TABLE 5. RESULTS OF SOIL-CLEANING TESTS.
ACUREX SOLVENT WASHING PROCESS
Run By amount of
number PCB added
1 37
2 503
3
4
5
6
7
8
PCB (ppm)
By
analysis
38
492
67
135
548
832
773
18
By amount of
PCB removed
38
436
72
141
1.941
910
678
16
Number
of
washes
3
10
6
6
12
12
10
5
Final PCB
concentration
(ppm)
<2
<2
<2
<2
<2
<2
<2
<2
Source: Weitzman 1985.
57
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Figure 10 gives the schematic of the pilot soil-washing system. It con-
sists of a soil contactor, dirty and clean solvent storage tanks, a solvent
reclamation system, steam generator, and ancillary piping equipment. It also
includes vent condensers and an activated carbon adsorption system for air
pollution control. Operation proved very simple; one person had no difficulty
operating it. Based on the results obtained with this system, a 5.4-m3 mobile
soil-washing system was designed and is now under construction.
The soil contactor is a semicylinder 1.2 m in length with a radius of
0.6 m. The soil washer is subdivided into two wash chambers along its axis.
The volume of each wash chamber is 0.3 m3. The isolated chambers allow opera-
tion of the soil washer with two different batches of soil at a time. Access
to each chamber for soil loading and removal, or to obtain soil samples for
analyses, is through two hinged lids that comprise the entire flat side of the
semicylinder. The lids are sealed with a Neoprene gasket and are clamped to
the main body for operation.
Each wash chamber is subdivided by filters installed in presses isolated
in slotted holders at each end of the central soil chamber. The available
volume in the soil chambers is 2 m3, although the chambers were not filled
entirely during operation. Approximately 0.2 metric ton of soil was cleaned
during each test.
The washer is mounted to a frame by the shaft along its axis. It is
rocked about its axis to agitate the soil/solvent mixture. It has a drive
mechanism for rocking the washer that swings the contactor 90 degrees in
either direction. Based on these successful results, field tests are planned
for a site in St. Louis, Missouri. The process tolerates up to 40 percent
water in the PCB extraction step. :
5.2.1.2.1 Costs—Basic estimated costs for the treatment alone range from
$130 to $390/m3 (Weitzman 1985). Adding costs for dredging, transport, and
placement of the treated sediments gives a total cost estimate of $196 to
$569/m3.
-------
VJ1
DEMISTER
CONDENSER
COMPR._
A1H
-M-
SOIL
I HASHER I
I I
I I
•H-
REBOILER
iFEED PUMP
V =7
CLEAN
SOLVENT
TANK
VENT
DIRTY
SOLVENT
TANK
f
O
rj
X
DRAIN
PUMP
CLEAN
SOLVENT
PUMP
CONDENSER
D
0°F
TRAP
CHILLER
VENT
ADSORBER
AIR POLLUTION CONTROL SYSTEM
Figure 10. Schematic of Acurex solvent wash process.
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5.2.1.3 O.K. Materials Methanol Extraction Process*—
The O.H. Materials methanol extraction process is being field tested in an
EPA Region III sponsored cleanup of PCB-contaminated soil at Minden, West
Virginia (Robert Caron 1986). The process involves slurrying the ground and
predried soil with methanol, separating and redrying the treated soil, and
solvent cleanup for resale. The cleanup employs activated carbon, which is
subjected to incineration (other treatments could be used) as an RCRA waste.
The cleaned soil is subjected to light land farming for degradation of any
residual methanol. Wastewaters are treated in a holding pond.
The field test report for this process is to be issued during the next 6
months. The description and evaluation given here are based upon the findings
to date, as obtained from the EPA Regional Office and from O.H. Materials.
A conceptual flow sheet for the process. Figure 11, was prepared to repre-
sent the system for evaluation purposes. The system size. 9.1 Mg/h (10 ton/h)
corresponds with the size of unit use'd in the field test. The process con-
sists of the following steps.
1. The toxic sediment is crushed to a size range suitable for drying. A
Grizzly grinder was used and performed satisfactorily for the material
processed (soil containing 15 percent water).
2. The sediment is dried to a water content of 5 percent. Drying is
carried out under negative pressure. Hollow Flite dryers were used.
In larger cleanup operations hot-oil-heated dryers of the same type
would provide greater capacity using commercially available dryers of
the same type.
The air flow rate was about 42 m3/min (1,500 ft3/min). Pollution
controls were used for cleanup of the exit gases and the particulates
recovered from the scrubbers were subjected to the methanol extraction
along with the dried sediments.
3. The dried sediment, plus recovered fines, was subjected to countercur-
rent extraction. The field test achieved a reduction from 400 to
"The O.H. Materials Corporation has subsequently merged with the Envionmental
Testing and Certification Corporation to form the Environmental Treatment and
Technologies Corporation.
60
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PCB Decontamination Process, O.H. Materials
Soil
x = 400 ppm
.15 water""*
Grinder
Methanol
40 gal/min
Clean
Sediment
<25 ppm
. Steam
Dryer
Exit Gas
J->. Wet Particle Scrubber
M^^SIudge
Methanol
Counter Current
Extraction, 2 Stage
Dryer
Dried sediment
10 ton's/hour
0.05 water
Solids
Removal
— Sludge —»•>
<25 ppm
PCB
pond
Methanol + PCB + fines (6.000 Ib/h)
Methanol
f
Water
Solids
Methanol
Rinse
~T~
Water
Rinse
10.000 ppm PCB to SCA as RCRA waste
for incineration
Methano' Condenser
To Holding
Pond
Cj To land farm or compost
(spray with sewage, microorganisms remove
residual methanol in 4 days)
Figure 11. Conceptual flow sheet, methanol extraction of PCBs
from discussion with Robert Caron, EPA, Philadelphia regional office.
-------
25 ppm. A two-stage extraction was used to reach the goals of 25 ppm
for the treated sediment. Greater reduction (to less than 1 ppm)
could be attained by adding additional stages to the extraction step,
and this was taken into consideration in ranking the potential of this
process.
4. The cleaned sediment was dried using a Hollow Flite dryer equipped
with a condenser for the raethanol carried in the exit gases. Air flow
rates for drying were 14 m3/min.
5. The dried, treated sediment was subjected to mild land farming, in
which it was surface-spread and seeded with microorganism-containing
waters. Residual methanol was found to be destroyed within 4 days.
6. The effluent from the extractors was heavily loaded with small par-
ticulate matter carried over from the sediments. About 2.7 Mg (6,000
Ib) of fines was carried over for each 9 Mg (10 tons) of sediment
treated. The solids were removed by settling. A centrifuge would
probably be more appropriate for this step. It would give better
separation and reduce carryover to the carbon adsorbers.
7. The separated particulates are combined with the main feed of cleaned
sediments for drying and land farming.
8. The effluent, after removal of particulate matter, is treated by car-
bon adsorption to reduce its PCB content from about 10,000 to 10 ppm.
This treatment produced a product suitable for resale as a
fuel.
While further test and evaluation of this process will be required before
its potential can be firmly assessed, it appears that the process is a viable
alternative to landfill. The PCB removal efficiency attainable will depend
upon the performance of the extraction system. There is, however, no reason
why additional stages of extraction would not improve the efficiency so that
the treated sediment would meet the goals of 1 to 5 ppm residual PCB.
The drying operation contributes to the cost and creates the need for
pollution controls, particulate recovery, and handling of the particulate as a
toxic waste. It may be possible to avoid drying if the process can be driven
by-50 percent methanol, such as would be generated if the sediments with
15 percent moisture were treated without removal of the water. One single-
stage wash would yield a diluted methanol solution. Then countercurrent
extraction could be applied to the sediments.
The extraction operation has a substantial particulate carryover problem,
which will need to be addressed for other extraction processes as well.
62
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5.2.1.3.1 Cost—Based on the conceptual process and the experience thus
far, the process is estimated to cost $400 to $514/m3, including dredging and
transport costs (Caron 1985). In the field application, methanol was pur-
chased at $0.69/gal (S0.18/L) and resold at $0.23/gal ($0.06/L).
•5.2.1.4 Soilex Solvent Extraction Process—
"Soilex" is a process in development at the Oak Kidge National Laboratory
(M. B. Saunders 1985). Kerosene and water were determined to be the solvent
of choice. Kerosene can be recovered for recycle by stream-stripping.
Soil-to-water ratios of 3 to 5 and soil-to-kerosene ratios of 3 to 5 were
found to be best. No difference in extraction performance could be determined
between 15- and 30-min mixing times. The kerosene retention in the soil was
about 25 vol percent. A three-stage batch pilot unit operating with a 6-to-l
volume ratio experienced soil feed PCB concentrations of 180 to 350 ppm and
discharge soil levels of 6 to 9 ppm. Lower soil values could be obtained
using additional stages.
5.2.1.4.1 Selection of solvent mix—The soil tested also had a high con-
centration of oils and tars, resulting in a total organic carbon concentration
of 10 to 20 percent. The PCB and oil were solubilized using the.kerosene
leaching solvent. Water was also added to the solvent mixture to help break
up the soil particles.
The extent of PCB extraction from the soil as a function of soil-water-
kerosene ratios and the mixing times was determined to define areas of accept-
able operation. To minimize operation and equipment costs, the water and
kerosene-to-soil ratios must be as low as possible. The data indicate that a
water-to-soil ratio less than 1.0 and/or a kerosene-to-soil ratio less than
1.0 result in a mixture that does not have enough fluid to allow for adequate
mixing and is therefore not acceptable for operation. A ratio of water-to-
soil and kerosene-to-soil greater than 5.0 requires processing a high volume
of material. A ratio of 3.0 to 5.0 for the water-soil ratio and kerosene-soil
ratio resulted in a system having good hydraulic mixing characteristics and
yielded a PCB leaching percentage of 84 percent.
5.2.1.4.2 Description—The pilot plant (Figure 12) consists of three
stages of mixing equipment. The plant is operated in a countercurrent mode;
63
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Soil -
Water
300*
Mixer 1
55*
Kerosene
Out
*PCB cone. mg/L
25*
Mixer 2
Recycle
Kerosene
In
Mixer 3
Soil Water 112*
112*
Figure 12. Soilex pilot plant.
-------
soil and water were added to stage 1 and clean kerosene to stage 3. Each mix
tank has a 200-L capacity and an air-driven mixer. An interstage solvent pump
and a 120-L solvent-hold tank allows the kerosene to be transferred in a
countercurrent mode. The distillation packed column system was 7.56 cm in
diameter by 2.4 m long, with an 18-L steam-heated reboiler and product con-
denser (Figure 13). The distillation unit was used to.steam-strip the re-
cyclable kerosene from the other oils and PCB.
5.2.1.4.3 Operation—The pilot plant is a 1-day batch-cycle operation.
Each day the solvent is pumped from each of the three mix tanks to their
solvent-hold tanks. The water-soil mixed phase is transferred by gravity to
the next stage, untreated soil and recycle water to stage 1, and fully treated
soil and water are discharged from stage 3. The kerosene is then drained from
the hold tanks to the next lower numbered mixer. The transfer operation takes
about 3 h to complete. The tanks are mixed for 4 h. Samples removed from the
mix tanks at 30-min intervals indicate that the mix tanks are at steady-state
after 90 min. After mixing has been stopped, the mix tanks are allowed to .
phase-separate for 16 h, thus consuming 1 d per batch.
5.2.1.4.4 Performance—The pilot plant was operated for 19 batch days.
Successful steady operation was obtained after 4 d. A 25-L batch of PCB and
oil from the solvent-extraction pilot plant was steam-stripped to recover the
kerosene in 3 h using 500 mL/min of water feed to the boiler operating at
110 °C. Twenty-two liters of kerosene were recovered at a PCB concentration
less than 5 mg/L. The PCB was concentrated to 15 mg/L (6 to 9 ppm).
Since the process operates best with from 42 to 45 vol percent water
present, it offers the advantage of accepting wet sludges for treatment with-
out drying. The drying operation, with its attendant pollution controls is
obviated. The process requires simple stirred tanks for extraction, as pro-
jected from the pilot plant. However, each batch of sediment requires 3 days
(72 hours) for treatment. After that, it is discharged holding 25 to 30
weight percent adsorbed kerosene. The sediment-solvent mixes were stirred for
only 90 min of each 24-h cycle, and the cycle was repeated three times. Most
of the processing time was spent in allowing the solid phase to settle and the
liquid phases to separate. More time- efficient separation techniques need to
be tested for applicability to the separation step.
65
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TOP
ON
ON
PRODUCT I
CLEAN
KEROSENE
2 mg/L PCB
DISTILLATION
COLUMN
BOILER
WATER
PHASE
SEPARATOR
PCB-CONCENTRATE
1,500 mg/L PCB
FROM SOILEX
"PILOT PLANT
55 mg/L PCB
PCB-CONTAMINATED
KEROSENE
Figure 13. Soilex steam distillation unit.
-------
The selected water, kerosene, and soil ratios gave good hydraulic mixing
characteristics and yielded "a PCB leaching of 84 percent." Since the soil
tested contained from 10 to 20 percent oils and tars with 300 to 600 ppm PCBs,
the solvent mix test dealt with PCB-containing oils spilled onto the soil. It
is not clear how the PCBs were distributed, how much was dissolved in ail
films surrounding the soil, or how much was adsorbed directly into the soil.
Tests using several more stages of extraction would be needed to demonstrate
that the extraction could, by use of more stages, achieve the 1- to 5-ppm
residual PCB levels desired. Studies of kerosene extraction at EPA and at New
York University may resolve this problem.
The process generates an RCRA waste (concentrated PCBs) requiring treat-
ment and disposal.
5.2.1.4.5 Cost—A rough cost estimate by RTI, based on increasing the
number of extraction stages to achieve desired background levels of PCBs in
the treated soil, is: $856 to $913/m3. This includes dredging, transporta-
tion, treatment, and redeposition of the treated sediments.
5.2.2 Vitrification
. i
5.2.2.1 Principles—
Vitrification stabilizes radioactive-contaminated soils by melting.
Large-scale tests have demonstrated the vitrification of 300 Mg per setting
(Timmerman 1985). At the high temperatures created (>1700 °C), the process
pyrolyzes organic materials. The products of pyrolysis diffuse to the surface
and combust. Any off-gases must be collected, monitored, and treated.
Remaining ash, along with other noncombustible materials, dissolves or becomes
encapsulated in the melt. Natural convective currents within the molten mass
help distribute the'stabilized materials more uniformly, the molten soil or
sediment is allowed to cool to a durable glass and crystalline form.
5.2.2.2 Battelle In Situ Vitrification Process--
In situ vitrification (ISV) is a patented process developed at Battelle
Pacific Northwest Laboratory for the U.S. Department of Energy as an in-place
stabilization technique (Timmerman 1985). Submerged sediments would be
67
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dredged before being subjected to this treatment. In evaluation of its poten^
tial application to soils contaminated with PCBs, an engineering-scale in situ
vitrification test with PCB-contaminated soil has been performed for the
Electric Power Research Institute to determine the fate of PCBs and their
byproducts when the process is applied.
5.2.2.2.1 Description—The process tested on a small scale is shown
schematically in Figure 14.
1. A 20-cm-diameter by 30-cm-deep zone of loamy-clay soil, containing
500 ppm PCBs was centrally located in a sealed metal container. The
contaminated soil was surrounded by noncontaminated soil and was 25 cm
beneath the surface.
2. Four cylindrical molybdenum electrodes were set on a 23-cm square to
surround the contaminated soil. The electrodes extended to a depth of
61 cm.
3. A path for electric current was established by placing a small amount
of graphite and glass frit mixture between the electrodes on the soil
surface.
4. Off-gases were collected and passed through a dual-stage activated
carbon filter to contain any PCBs or decomposition products released.
Online grab samples of exit gases were taken from a sample port. The
samples were analyzed for chlorine and hydrogen chloride.
5. Electric power was applied for a 6-hour period. A vitrified block
(220 kg) and 0.14 ra3 was produced. The melt extended to a depth of
81 cm.
6. In addition to sampling off-gas emissions, residues in off-gas lines
and containment equipment, the migration of PCBs into the surrounding
soil, and the residual level of PCBs in the vitrified block were
monitored.
5.2.2.2.2 Performance data—Online grab samples revealed less than
detectable quantities of chlorine and hydrogen chloride (<0.33 ppm and
<0.2 ppm, respectively). Data from off-gas release and soil container smears
provided the most quantitative values on the release from the melt during and
after processing. Information collected from the adsorption tubes and the
smear sample extractions indicated a 4.4-mg total off-gas emission, 1.1 rag of
which was deposited on container surfaces. These off-gas releases accounted
for 0.05 wt* of the initial PCB quantity, corresponding to a greater than
99.9 percent thermal destruction and removal efficiency for the ISV process.
68
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Electrical
Metering
Valve
Sample Train
Sample Port
Water Air Desiccant
Impingers Dryer
Piping
Supply ._J
Electrodes
Off Gas
Vitrification Zone
Surrounding Soil
Figure 14. Engineering scale vitrification system and sample locations.
69
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This does not include the removal efficiency of the off-gas system; therefore,
a system ORE cannot be calculated from the available data. Activated carbon
filters can effectively contain any of the off-gas emissions.
Analyses of the florisil adsorber also indicated a small amount of furan
(PCDF) and dioxin (PCDD) generated in total quantities of 0.4 ug and 0.1 ug.
respectively. Only the tetra and penta isomers of the PCDF were detected, and
only the hepta and octa isomers of the PCDD were detected. These small
quantities are less than the reported amounts typically generated from a PCB
fire and do not represent a hazardous operational concern.
The vitrified mass showed no detectable residual level of PCB, which is to
be expected considering the high processing temperatures. Also, no PCB con-
tamination was detected in the majority of soil surrounding the vitrified
block, indicating that migration outside the vitrification zone was not a
significant problem. A few samples directly adjacent to the block contained
measurable concentrations up to 0.7 ppm, which is acceptable. These results
indicate that the vitrification rate must be higher than the diffusion rate of
volatilized PCBs in soil, thus overcoming migration away from the hot molten
mass.
The product of this process is a solid glass and crystalline block. This
form may be more costly to redeposit. There may be fewer options than would
be available for ordinary sedimental material. The nature and extent of emis-
sions from the melt would likely vary from one type of sediment to another.
Sediments containing significant amounts of organic matter would lose all of
it by pyrolysis and vaporization. To conserve energy usage, sediments high in
moisture should be dried prior to treatment.
5.2.2.2.3 Cost—The cost of using the vitrification as a technique for
in-situ treatment has been estimated by the developers. The estimate includes
expenses from four categories: site preparation and closure activities, annu-
al equipment charges, operational costs, and consumable" supplies including
electrical power and molybdenum electrodes. These costs are estimated to be
between $150 and $330/m3 depending on electrical power rates and soil moisture
content. Soil moisture content increases the cost by requiring more energy
and time to vitrify a given volume of contaminated soil because the water in
70
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the soil oust be evaporated. The total cost of using this approach requires.
for submerged sediments, the addition of dredging, transportation, and redepo-
sition costs.
The solidified blocks of treated sediment could not be disposed of by land
treatment. If treated at a hazardous waste facility, they could be landfilled
there. The cost of such disposal would probably be the regular charge for
hazardous waste disposal, $260 - $490/m3. The treated material is estimated
to be eligible for delisting, however, and redeposition at a lower cost should
be possible. Given that the physical form of the treated sediments will limit
somewhat the available locations for its redeposition, a cost of $72/m3 has
been estimated. This cost is less than that of controlled, managed land
treatment ($111) since the material would require no control or management.
It is greater than the $33/m3 cost of short-term land treatment. The overall
cost estimate is thus:
Cost, $/m3 = ($20 dredging) + ($13 - $126 transporation)
*• ($150 - $330 treatment) * ($72 redeposition)
= $255 to $548.
5.3 BIOLOGICAL TECHNOLOGIES
5.3.1 Microorganisms and Enzymes
5.3.1.1 Principles—
Biological technologies for PCB treatment include the use of free microbes
or their enzymes. The microbes may be bacteria or fungi and may act
aerobically (or anaerobically) or facultatively. They may be indigenous
microorganisms.conventional chemical mutants, or recombinant microorganisms.
Their action may result in partial or 'total degradation of the PCBs. Total
degradation, termed mineralization, occurs when the metabolic products are
C02, 1130, and HC1. •Their action may take place within the cell (bacteria) or
external thereto; (fungi).
Enzymes may be applied as free-flowing solutions or bonded to a solid
substrate. The use of enzymes alone has great conceptual potential but has
not progressed very far at this time.
71
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Thirty-four bacterial strains and five fungal strains have been shown to
have varying degrees of competence in degrading PCBs (Unterman et al. 1985;
McCormick 1985; Rochkind et al. 1985, Bumpus et al. 1985. Isbister et al.
1984). These microorganisms metabolize FCBs using enzymes specific to the
strain. Since most enzymes are notably specific in their actions, different
enzymes catalyze the reaction of different FCB isomers (termed cogeners in the
biotechnology literature). In some cases, the cogener may be metabolized only
partially by a particular species, and a product (e.g., a chlorobenzoate) may
accumulate. In a parallel situation, another species may be able to metabo-
lize that product further, although the second species may lack enzymes needed
to metabolize the parent PCB. By themselves, neither species could mineralize
the cogener. However, a mixed culture might act in concert mineralizing the
product resulting from metabolism of the substrate by the other species. A
consortia of more than two species may be required to mineralize a substrate
and the effective species may be bacteria, fungi, or a mixture of the two.
Some cells cometabolize PCBs; that is, they metabolize a PCB cogener while
obtaining their carbon and energy from other sources. Such metabolism may be
partial or complete and depends upon enzymes already active in the cell.
Biological technologies include a very broad spectrum of potential
capabilities, many aspects of which are being explored. True measures of
their ultimate capabilities for PCB-destruction cannot yet be made. In the
following sections, recent developments in mutant and enzyme technology are
described.
5.3.1.2 Indigenous and Conventional Chemical Mutants—
Indigenous and conventional chemically mutated microorganisms (those found
growing naturally in diverse PCB-containing soils and sediments) have been
isolated, identified, and tested for PCB-degradation capability using an assay
mixture containing five types of cogeners selected to pro- vide.different
resistances to enzyme attack (Bedard et al. 1985). The assay mixture was
composed of the following types, selected from the over 100 different coge-
ners:
1. Single-ring substitution: 2,3 Dichlorobiphenyl
2. Double para substitution no free
3,4 sites: 4,4' Dichlorobiphenyl
-------
3. No free 2.3. sites: 2,5,2'.5' Tetrachlorobiphenyl
4. No adjacent unchlorinated sites: 3.5.3',5' Tretrachlorobiphenyl
5. Two or more ortho chlorines.
steric hindrance: 2.6.2*.6' Tetrachlorobiphenyl
Table 6 lists the results obtained using 25 strains, including 15 isolates
and 11 unidentified field isolates (e.g., H337 is an unidentified gram-
negative organism isolated from Hudson River sediments).
The results identify Alcaligenes eutrophus H850 and Pseudomonas putida
LB400 as the best microorganisms, both being able to degrade. 13 test cogeners
80 to 100 percent.
Table 7 lists 10 additional strains of bacteria studied by different
investigations. Of these, the Arthrobacteria degraded the most PCB cogeners.
The table also lists 5 fungi that have been studied. To date, the fungi show
less effectiveness than the bacteria (2 percent vs 80-100 percent).
The degradative pathways and cogener preferences differ among the micro-
organisms. Many bacteria oxidize PCBs via chlorobenzoic acid intermediates
and often accumulate the chlorobenzoate products (Furukawa, 1982). The major
pathway proposed for A^ eutrophus H850 involves a dioxygenase that preferen-
tially attacks at carbon positions 3.4 (Unterman et al. 1983). In contrast,
Corynebacterium sp MB1 probably employs a more common 2,3 dioxygenase mech-
anism.
Genetics studies of PCB-degrading bacteria have demonstrated that some of
the effective strains contain one or more plasmids (Unterman et al. 1985).
Plasmids are stable extrachromosomal circular double-stranded DNA replicons
that are inheritable but are also dispensable. Mutants of H850 that have lost
their plasmid have also lost the ability to metabolize PCBs.
Mutations that living cells may undergo alter the genetic message. Some-
times the alterations in the DNA code may lead to alteration of the cell's
metabolism. Some mutations allow the cell to survive in the presence of
potentially toxic compounds. In other cases, the cell acquires the ability to
use previously unsuitable substrates. Some agents, including UV light, some
73
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TABIE 6. PCB DEGRADATION BY BACtERIAl STRAINS: PERCENT DEGRADATION 6V COCENER .
(RAPID ASSAY TEST)
PCB cog«n«r («)
B.cl.rl.l .tr.in 2,1 2,4' 2.6.4- 2.2' J.», I.S.I' 2.1, 2,4,6, 2,6, 2,1,4, 4,4- 2,4,4* 2,4, 2,4. 1,4, 2,6, 2,4,6, 2,4,6,
2',!' 2',t* 2'.!' !',«' 2'.6' l',4' 2'.4' l',4' 2',S' 2'.6' 2'.4'.6'
Acldovor.nt group H762 M-IM M-IM M-1M M-IM
Pllel M-IM M-IM M-79 26-19 26-19 M-IM M-IM 26-19
Alc.lla«n«i .utrophm HIM M-IM M-IM M-IM M-IM M-IM M-IM M-IM 46-69 M-IM M-IM 66-79 (6-IM 46-61 66-IM 46-69 M-IM M-IM 46-69
Alc«llp«n»» f»»c«ll» PI 4|4 M-IM M-IM 26-18 M-IM 4a-6»
C»rm«b«et«rlu«i •» Ml M-IM OS-IB* M-IM M-IM M-IM 66-79 M-IM M-IM 46-69 M-IM M-IM M-IM
Pl«u« t«ttoit«ronl HI2( M-IM M-IM «»-T» M-IM M-IM 2*-M M-IM M-IM 4I-6B
HIM M-IM M-IM M-IM M-IM M-7» M-IM 41-69 46-69 66-79 66-79
N4M M-IM M-IM M-IM M-IM M-IM 66-79 M-IM 96-IM 46-69
P««udo«on«i c»p.c.« NJB 96-IM 96-IM 46-69 26-19 26-19 66-IM 66-79
PI 764 M-IM 66-IM 46-69 M-IM 96-IM 26-19
H 261 (6-IM 96-IM 68-IM 96-IM
Pt«
-------
TABLE 7. PCS DEGRADATION BY BACTERIAL AND FUNGAL STRAINS: LONGER TESTS
Reference
2,3
2.4'
2,5,4'
2.2'
2,3.2' ,3'
2.5,2'
2.4,4'
3,4,3',4'
«.«'
2.4.5.2'.4',5'
2.5
3.4,3'
3,4
4
2,3,2'
2.3,4'
Bacterial strains
Alcaligenes Klebsiella
Acinobacter 8M2 Alcaligenes AchrorobKter Arthrobacter Facultative (coqener not
sp P6 (3-day test) sj Y42 sp PCS w plasmid anaerobe B206 iiijerjixkij specified)
McCormick, 1985 Rochkind et al., 1985 Rochkind et al., 1985 Rochkind et al., 1985 Isbister et al, 1984 Rochkind et al.. 1985 HcConnick, 1985 McCormick, 1985
80-100% NO
80-100% ND
80-100% ND
ND
80-100%
NO 80-100%
80-100% ND
1
NO ND ND ND ND ND
(continued)
ND=percent not determined.
-------
TABLE 7 (continued)
Reference
2,3
2.4'
2,5,4'
2,2'
2,3,2'.3I
2,5,2'
2,4,4'
3,4,3',4'
4,4'
2,4,5.2',41.5'
2,5
3.4,3'
3,4
4
2,3,2'
2,3,4
Bacterial strains (continued)
Norcadia
10603
(2-veek test)
Pseudcnavis
splsol
Rochkind et al. 1985 Rxhkind et al. 1985
60-79%
60-79% ND
60-79%
(10-veek test)
60-79%
60-79%
60-79%
60-79%
fungal strains
Candida tropical is Cunninghamena CunninghameVja Phanerochaete
(cogener not echlnulata elegans chrysosporium Rhizopus
specified) (Thaxter) (cogener not specified) (white rot fungus) Japonicus
McCorroick 1985 Rochkind et al. 1985 McCormick et al. 1985 Buipnus et al. 1985 Rochkind et al. 1985
2.0%
2.0%
ND
ND
ND=percent not determined.
-------
kinds of radiation, and some chemical agents, cause increased rautagenesis.
These mutations are characterized, by being randomly distributed across the
ONA. Mutations can be selected by applying selective pressures to a popula-
tion, creating an unfavorable environment in which only those cells that have
nutated so as to adapt to the environmental situation will survive. Such
•adaptation may take months before the altered population is large enough to be
observed.
5.3.1.3 Enzyme Mechanisms—
Limited studies on the degradation of specific chlorinated biphenyl com-
pounds by pure strains of bacteria have established some general features of
PCB metabolism (Rochkind et al. 1985). A few strains have been shown to
mineralize some chlorinated biphenyls. In most cases, bacteria can degrade
one ring of a chlorinated biphenyl but are unable to degrade the resulting
chlorinated benzoates. These compounds accumulate in pure cultures. Other
strains have been shown to be capable of completely mineralizing chlorinated
benzoates (e.g., the hybrid strain of Pseudomonas sp B13 carrying the rela-
tively nonspecific oxygenase of P^ putida mt-2 carried on the TOL plasmid).
Mixed cultures of bacteria have been shown to mineralize PCBs with four or
fewer chlorines per molecule. More heavily substituted PCBs appear to resist
degradation to a greater extent.
The mechanism of hydroxylation of PCBs by bacteria has not been eluci-
dated, nor have the enzymes mediating the steps in the proposed pathways been
isolated. Two pathways have been proposed. The first involves initial
hydroxylation in the 2.3-position of the less substituted ring, followed by
meta cleavage and subsequent degradation of the aliphatic portion of the
molecule to form substitiated benzole acids. Chlorines on the aliphatic car-
bons are lost during this-process.
COOH
77
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However, this may not be the. mechanism for degradation of PCBs substituted
in all the ortho positions. A second pathway, based on the action of a mono-
oxygenase in bacteria has been proposed after discovery of 4-hydroxy-4'-
chlorophenyl in extracts of bacteria cultures incubated with 4-chlorobiphenyl
(Catelani et al. 1971). More evidence corroborating this mechanism is needed.
Unterman et al. (1985) proposed that the major pathway of PCB metabolism in A...
eutrophus H850 utilizes a dioxygenase that preferentially attacks at carbon
positions 3,4; while Corynebacterium sp. MB1 probably employs a more common
2,3 dioxygenase.
Limited evidence on fungal metabolism of PCBs indicates activity of a
monooxygenase.
Little has been done to prepare or work with enzymes alone, separated from
the organisms, despite the conceptual attractiveness of the approach. The
separation processes for PCB-degrading enzymes are yet to be developed. Some
enzymes may be cell wall bound, requiring special handling in their prepara-
tion. At present, little is known concerning the use of enzymes alone for i'CB
decontamination of sediments.
5.3.1.4 Bio-Clean Process—
The Bio-Clean process is a biological treatment process developed by
Bio-Clean, Inc., Bloomington. Minnesota. It has been well demonstrated for
PCPs. It requires further testing with, perhaps, the use of some additional
strains of microorganisms to bring it through the pilot stage for PCBs. It is
listed here as a representative bio-process that has potential application and
can be made available commercially. It does not require pretreatment to
dewater sediments, and it does not appear to generate any RCRA wastes or emis-
sions. Bio-Clean has proposed to process the sediments as they are dredged,
using a series of nine floating barges with processing units on board. This
would eliminate the need for sediment transport and replacement, and would
eliminate the associated costs.
5.3.1.4.1 Description—The process involves two steps: (1) extraction.
sterilization, and solubilizing the contaminants using high pH and tempera-
ture, and (2) bacterial destruction of the contaminant. These steps generally
require 3 days. Standard digesters that can handle 22 to 28 m3 of sediment
78
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(dry bases) are used in sets of three to provide a daily capacity in multiples
of 22 to 28 m3/day. (Larger units are discussed later in this section).
Figure 15 is a flow diagram of the process as applied to contaminated soils.
The processing cycle requires four steps:
1. Contaminated sediment is charged to the digester, in slurry form if so
received. The final digester charge will be approximately 2/3 water
and 1/3 solids. The charge is made alkaline with sodium hydroxide (or
other alkaline hydroxide), then heated to approximately 82 °C, at
which temperature it is held for one hour. The mix is agitated to
promote solubilization of the PCBs.
2. After the extraction, the slurry is cooled to 30 °C, neutralized and
inoculated with a selected microorganism(s) to initiate decontamina-
tion. The slurry is kept under these conditions for 48 to 72 h as
required, until the desired degradation has been attained. The exact
time requirements must be determined by tests for each particular
decontaminant. The degradation is an aerobic process and uses sterile
filtered air for oxygen.
3. A treated batch of sediment is discharged to a dewatering pit where
the sediment is separated for redeposition. The material is sampled
and tested to determine the concentration of residual PCB prior to its
relocation. The water is also analyzed for PCBs and thus disposed of
in a manner suitable for the particular site (e.g., through sanitary
sewer systems, storm sewer systems, or percolation into the ground or
recycle).
4. At the end of the decontamination period, the cycle begins again at 1.
5.3.1.4.2 Residual PCB concentration—In laboratory tests, selected PCB
cogeners have been reduced to 10 ppb in 48 to 72 hours. The process utilized
Arthrobacteria sp under aerobic conditions.; Further testing.must be done
using the specific sediment of interest to determine the specific capabilities
for given PCBs. Bio-Clean is equipped to do screening tests. However, a more
extensive test and development study is needed to assess the potential of the
process adequately. In.such tests, other species of microorganisms that have
shown broad capabilities for degrading many PCBs could be tried (e.g.,
Alcaligenis eutrophus and Pseudomonas putida LB8400). .
5.3.1.4.3 Conditions/limitations—The organisms are naturally occurring.
Their degradation products have been shown to:be 'C02. NaCl and bacterial
cells. Supplementary nutrients (ammonia nitrogen, phosphorus, and potassium)
would be required with some sediments.
79
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Contaminated
Dirt Pile
oo
o
Wood Rocks Screened
Debris & Metal 'Dirt
Debris
Caustic
Storage
a o
£ Digester #1 *•
1«? Digester #3 *•
j t
15 psi
Steam
r
L
i
-^ Onsite
~Y Well
1
Boiler
Make-Up
Water
Ammonium
Acid ; Phosphate
Storage Storage
G ft t b
Recycle Water Sump #1
•
_____ '. l to Sower
Sump #2
Pit '^^////^//W/4?Z>
7//////^^
Land-Spread /V/jfiyff//////////////
n$lt8 ^^rf^^Vr''^
•v ysytyffiffi/Y/ffldffl
i ,
Natural
Gas or
Other
Fuel
Figure 15. Bio-clean process applied to contaminated soils.
-------
Very high PCB concentrations (e.g., >300 ppm) inhibit the degradation
process. It may be slowed down or halted. Contaminated sediments may vary
significantly in PCB loading. To avoid inhibition of the process, the sedi-
ments could be slurried in a premix tank for blending to control PCB levels.
5.3.1.4.4 Availability—Laboratory-scale and pilot-scale (760 L) evalua-
tion facilities are available at Bio-Clean. Pilot tests could be carried out
under sponsorship.
5.3.1.4.5 Scale-up—For large-scale cleanups, large horizontal tank
digesters (each handling 540 Mg of sediment per charge) or floating barge
tankers would be used. These would be used in sets of three. Each set could
treat an estimated 115,000 m3/year of contaminated sediment. Three sets would
treat the estimated 382,000 m3 of contaminated sediments in the Hudson River
in 13 months or less with large barge tankers (based on 355 days operation per
year).
5.3.1.4.6 Cost—The estimated cost of treatment using the Bio-Clean proc-
ess on floating barges is $191 to $370/m3. This includes dredging at $20/m3,
and treatment costs at $171 to $350/m3.
5.3.1.5 Sybron Bi-Chem 1006 PB/Hudson River Isolates Process—
The Sybron process is a conceptual process still in the laboratory scale
(Kopecky 1985). Information obtained from the company was very limited, and
its evaluation is correspondingly limited. The process may be able to operate
under both aerobic conditions or anaerobic conditions with facultative aerobes
and supplements of nitrates. Further studies to define an anaerobic process
concept and principles have been proposed (Kopecky 1985; and Rhee 1985a).
5.3.1.5.1 Description-—This process has not been developed sufficiently
to permit a description in terras of unit operations. Information provided by
Sybron includes tests of their Bi-Chem 1006 PB for removal of PCBs from a
municipal sewage sludge. (Status Report New York Department -of Environmental
Conservation, May 21, 1985). The sludge contained 100 ppm of PCBs. After
treatment for an unspecified time with Bi-Chem 1006, the PCBs were reduced to
undetectable levels (<1 ppm). Hudson River sediments were also treated with
81
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Bi-Chem 1006. In 6 weeks of incubation, the concentrations of a raonochlori- 1
nated biphenyl and a dichlorinated biphenyl were reduced by half. When the
Hudson River isolates were added to the Bi-Chera 1006, the sediment concentra-
tions of these particular biphenyls reduced slightly more than half in the
same incubation period. However, a second dichlorinated biphenyl was not
reduced at all during this period by either treatment.
5.3.1.5.2 Application—The conditions under which microorganism activity
occurs (anaerobic or facultative) would permit two potential modes of applica-
tion to submerged sediments: in situ decontamination and treatment under
containment of dredged sediments. In situ decontamination would involve the
injection and mixing of microorganisms and nutrients in the submerged sedi-
ments, and, perhaps, maintaining them in place for rather long periods of
time. As a treatment under containment, the organisms and nutrients would be
fed from a mass culture system to sediments being pumped to holding sites.
Effluents from the holding site would be subject to treatment for leached
nutrients and other components from the inoculation process. Proof-of- prin-
ciple laboratory tests for in situ treatment have been proposed. Engineering
for in situ application has not been addressed. The parameters for mass cul-
ture and the feed system for use in conjunction with the sediment containment
site are not currently available for assessment.
The possibility of an in situ treatment process inherent in this approach
is a subject for fundamental research. Until the concept is more clearly
defined, the approach cannot be assessed. The advantages of in situ treatment
are obvious, however.
Data needs relate strongly to the engineering requirements of such a proc-
ess. The required doses of organisms and nutrients must be determined and
related to PCB degradation efficiency. The scale of resources needed to treat
300,000 m3 of contaminated sediment needs to be determined. The extent of
leaching of nutrients, and of dissolution of toxic substances, needs to be
estimated if the system is to be an open containment type.
Cost estimates for this application process could not be made, due to the
available information..
82
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5.3.1.6 Composting—
Aerobic and anaerobic composting of PCB-contaminated soil has been studied
on a laboratory scale by Isbister, Anspach, and Kitchens (1984). Experiments
were carried out with soil that was intentionally spiked with PCBs
(Aroclor 1242). Mason jars were used to contain the compost materials. . For
•the aerobic composts, warmed air was first drawn through a sodium hydroxide
trap to remove any €03 and then through a water trap to humidify the air and
remove any caustic material. The scrubbed air was then drawn through the
compost materials. The atmosphere above the compost was continually drawn out
through sulfuric acid, sodium hydroxide, and activated carbon traps to remove
any gaseous biodegradation products. The dead .traps prevent contamination of
the composts of individual gas traps in case of vacuum failure. For the
anaerobic composts, the initial NaOH scrubbing trap was eliminated. The
anaerobic composts were initially flushed with nitrogen to remove oxygen from
the system, and they were flushed every 3 to 4 d thereafter to change the
atmosphere in the composting vessels.
Each compost was made up of 23.7 g of alfalfa hay, 24.7 g Purina Sweetena
Horsefeed and 5 g of lakeland soil (a total of 50 g dry wt.). The soil was
spiked to yield 2.000 mg/kg of Aroclor 1242 in the total compost (dry wt.
basis). The compost materials were thoroughly mixed, and the composting proc-
ess was started by addition of sufficient water (containing primary effluent
and horse manure) to give the compost a 60-percent moisture content. The.
composting apparatus was then placed in a 55 °C incubator and attached to the
vacuum system. The temperature of each compost was monitored daily by means
of a thermocouple placed within the compost materials.
The composts were sacrificed after 2- and 4-week intervals, and each com-
post was examined for appearance and smell. The pH was determined on a
portion dispersed in water. The remainder of each sample was dried 24 h at
60 °C and ground with a hammer pulverizer .to 18 mesh. The powder was then
mixed. Two subsamples were Soxlet-extracted with a mixture of benzene, ace-
tone, hexane, and methanol. .(The extraction efficiency of Aroclor 1242.from
uncomposted materials ranged from 83 to 89 percent.) Each extract was diluted
and analyzed on a Varian 3700 gas chromatograph with autosampler and electron
capture detector. A Hewlett-Packard 5880 controller/integrator was used to-
cdntrol the Varian gas chromatograph.
83
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Aerobic composting resulted in the greatest decrease in PCB concentration,
with an average reduction of 62 percent in four weeks. Residual concentra-
tions ranged from 504 to 688 ppm. Anaerobic composting resulted in 27 to
47 percent reduction in four weeks, with residual concentrations ranging from
825 to 1.120 ppm.
The results of composting will, of course, depend upon the kind of micro-
organisms present. This study evaluated the effect of composting of individu-
al isomers by comparing selected normalized areas of the chromatograms with
those of controls. These comparisons showed significant decreases in the
trichlorobiphenyls and one of the tetrachlorobiphenyls contained in the
Aroclor 1242 after two weeks. No decrease in the higher chlorinated biphenyls
was observed for this period. After 4 weeks, however, significant decreases
in all of the chlorinated biphenyls occurred, with a loss of 25 percent of the
trichlorinated biphenyls remaining. Anaerobic composting showed significant
decreases in all of the chlorinated biphenyls also after 4 weeks.
Composting would appear to require considerable work-site space to handle
the sludge, with considerable monitoring to determine the progress of the
process. Lack of control of weather and other conditions would make the proc-
ess uncertain in terms of time and effort required.
5.3.1.6.1 Cost—Data for composting are insufficient to provide a basis
for cost estimates. Considerable extrapolation of the performance data would
be required to project process conditions for desired residual PCB concentra-
tions.
5.4 SUPPORTING PROCESSES
The dredging of submerged sediments is a necessary step prior to applica-
tion of the treatment processes, except, perhaps, for the Sybron process.
Many of the treatment processes have wastewater streams, the cleanup of which
must be considered in their application. This section assesses dredging and §
wastewater treatment as supporting processes. '
-------
5.4.1 Dredging
5.4.1.1 Classes of Dredges—
Dredging practices have historically been designed to achieve the greatest
possible economic return, with secondary consideration of environmental .
-aspects. Because sediment removal is .required as a first step in the applica-
tion of most treatment technologies, the various approaches to dredging have
been evaluated for suitability in bottom recovery of hazardous chemicals (Hand
and Ford 1978). For the evaluation, dredging equipment has been classified
according to mode of operation: mechanical, hydraulic, pneumatic, and special
purpose (other). It is recognized that these classes are neither mutually
exclusive nor parallel. However, they do serve to sort the equipment conveni-
ently for comparison of suitability for various job sizes and sediment proper-
ties and for assessing their overall potential use in different scenarios,
e.g., nonnavigable waters and navigable rivers.
Mechanical dredges remove bottom sediments by directly applying mechanical
force to dislodge, excavate, and bring to the surface material at almost in
situ densities. Most mechanical dredges deposit the dredged material into
scows or barges for transport to a disposal site. Two basic configurations
useful in dredging hazardous materials or contaminated sediments are the clam-
shell or grab dredge and the dipper dredge. Both types are normally barge-
mounted and deposit excavated material into scows or a disposal area immedi-
ately adjacent to.the worksite. Production rates vary according .to cycle.time
and bucket capacity up to a maximum of about 380 m3/h (500 yd3/h), limiting
them to spills covering relatively small'areas. •
Mechanical dredges cause turbidity and resuspension of sediment due to
loss of fines during the. hoisting process.. They would be ineffective against
a free liquid contaminant on the bottom. Mechanical dredges can work in rela-
tively close quarters and around structures,, obstacles, and debris. .The clam-
shell is capable of deep water excavation in excess of 30.5 m (100 ft). .••;•.-
Hydraulic dredges, .including, plain suction, dustpan, cutterhead, and hop-
per dredges, remove and transport -sediments in liquid slurry form using
diesel- or electric-powered hydraulic pumps with discharge pipes ranging from
15 to 122 cm in diameter. The slurries, containing 10 to 20 percent solids by
85
-------
weight, are normally transported through pontoon-supported pipelines for dis-
tances up to several thousand, meters. The hopper dredge stores the material
onboard instead of transporting it.
The plain suction dredge entrains a water-sediment mixture and is limited
to. free-flowing sediments such as sand or unconsoiidated silts and clays. It
would probably be effective against intact masses of liquid or granular solid
chemicals.
The dustpan dredge uses high-pressure water jets around the edges of the
flared dredging head to loosen cohesive sediments and create a slurry. This
action often causes relatively high turbidity in the dredging area. •-<-
The cutterhead dredge employs a powerful rotating mechanical digging
apparatus to loosen hard materials and generate the slurry.
Hydraulic pipeline dredges are capable of very high production rates,
e.g., in excess of 7.650 m3/h (10,000 yd3/h) for the largest diameter pipe-
lines. They are cumbersome, however, because they rely on anchors, cables.
and winches to move them across the worksite.
Hopper dredges are large, self-propelled, seagoing vessels with on-board
storage hoppers ranging in capacity from 382 to over 6,100 m3. They have
suction pipes mounted on hinged drag arms on each side of the vessel hull. :
The drag arms trail back as the dredging head is dragged along the bottom at
forward speeds up to approximately 13.3 km/h. During normal operation, the
heavier sediments settle in the hopper, and excess water with considerable
suspended fine-grained matter flows over weirs into the water, a practice that"
would generally not be acceptable when dredging hazardous material. These
dredges can work in relatively rough and open water, in relatively high cur-
rents, and in bad weather. They can also work in shipping lanes with little
disruption of traffic.
The pneumatic dredge features a crane-suspended pneumatic pump, but other-
wise it is basically a hydraulic pipeline system. The pneumatic pump is oper-
ated by an air compressor aboard the barge. The pump consists of three
cylinders that are alternately filled with sediment by hydrostatic pressure
86
-------
and emptied through check valves into a common header line by closing the
inlet and applying compressed air. The sediment does not have to be in liquid
slurry form; rather, it can be handled with solids contents corresponding to a
plastic state or up to about 70 percent solids by volume. There is no theo-
retical depth limitation to pneumatic pumps as there is with surface-mounted
centrifugal pumps; moreover, because they are crane-mounted, pneumatic systems
could be useful in and around port structures. The normal mode of operation
is with a scooplike dredging head that is pulled with cables into the excava-
tion, resulting in a minimal solids resuspension.
A pneumatic dredge was used in the Duwamish PCB incident as well as sever-
al harbor cleanup operations in Japan. The pneumatic dredge appears to have
high potential in the cleanup role.
Special purpose dredges include small hydraulic dredges such as the
MUDCAT, the handheld suction devices, and the land-based earth-loading equip-
ment used in the dredging mode. The MUDCAT is available from the National Car
Rental agency, its designer and developer. It has undergone limited EPA test-
ing in a hazardous materials cleanup role. It is a 9-m, pontoon-mounted,
20-cm hydraulic pipeline dredge featuring an augerlike cutting device mounted
horizontally along a dozertype blade that feeds sediment to the suction intake
of a diesel-driven centrifugal pump. The system is mounted on a hydraulic
boom. The MUDCAT can dredge a swath 2.4 • wide by 0.46 m thick in waters as
shallow as 0.46 m. Its Maximum dredging depth is 4.6 m.
Handheld devices include a suction hose manipulated by a diver, with a
pump and storage tank aboard a barge, boat, or land-based truck. Practical
use would be limited to very small spills, precision dredging of intact masses
of contaminant, or well-defined concentrations in difficult locations.
Land-based earth-loading equipment ranging from farm-tractor-sized loaders
and backhoes to giant shovels and draglines used in strip mining could have
valuable application to spill response, particularly for land spills and
spills in small-streams. .
87
-------
5.4.1.2 Dredge System Evaluation—
In a study of the impact of dredging, Carcich and Tofflemire (1981)
examined potential adverse effects on the ecology and on the quality of drink-
ing water drawn downstream from Hudson River sites of contamination. They •
concluded that ecological effects would not be significant and that dredging
would reduce the overall risk of contamination of downriver water supplies.
The basic types of dredges have been evaluated by Hand and Ford for over-
all potential for hazardous material contaminated sediment recovery in differ-
ent general environmental settings. Their ratings for nonnavigable waters and
for rivers are shown in Tables 8 and 9. The column headings correspond to
those site-specific factors identified as likely to be critical in each gener-
al setting and that are at the same time amenable to at least a qualitative
numerical rating.
Each major type of dredge has been assigned a numerical score from 0
(worst) to 10 (best) for each of the rating criteria. Each of the criteria is
assigned a weighting factor in accordance with its relative importance in
influencing the suitability of dredges in each of the spill settings. A
weighted average is computed to arrive at a score between 0 and 10 for each
dredge in each spill setting; the weighted average score should be viewed as
an overall indication but not an absolute measure of the dredge's potential
for use in a given setting. 'Dredges with higher scores may typically do a
better, faster, or more complete job with less harm to the environment, based
on the criteria used, than those with lower scores. The particular circum-
stances present at an actual spill site would, of course, have to be examined
and weighed against the capabilities of specific candidate dredges before a
final decision could be made.
The "notes" columns in the tables are for certain qualifications, limita-
tions, and other points that deserve special mention but are not-reflected in
the ratings themselves: •
This evaluation makes no attempt to consider or quantify the possible
influence of chemical-specific considerations. Dredging to remove hazardous
chemicals from the bottom is principally a material relocation problem and the
particular chemical spilled in most cases does not add significantly to the
88
-------
TABLE 8. DREDGE EVALUATION MATRIX; SPILL SCENARIO: LAND AND NONNAVIGABLE WATERS—ALL SPILL SIZES
Job size compatibility
Small
<1,000
yd3
(786m3)
Weighting Factor 6
Mechanical NA
Dipper
Clamshell
Hydraulic NA
Cutterhead
(and plain ...
suction)
Dustpan
Hopper
oo • •
vo Pneumatic 6
Other
Mudcat 9
Handheld vacuum 6.
Land-based 9
earth-loading
equipment
Med i um
1,000- Large
<200.000 >200.000
yd3 yd3
(163,000 m3) (>163,000
6 6 .
NA NA
(Setting
NA NA
(Setting
'
8 6
7 2
3 0
9 9
.
Solids
Resuspen-
slon of
sediments
and con-
m3) content taminants
1
NA
normal ly
NA
normal ly
7
6
2
10
2
NA
inaccessible to
NA
Inaccessible to
7
6
9
2
Debris
and struc-
tural
obstaclea
1
NA
this type of
NA
this type of
7
4
8
8
Transpor-
tation
/mobili-
zation
time
2
NA
equipment)
NA
equipment)
3
7
8
9
Overall potential
Smo 1 1 Med i um
yardage yardage
NA NA
NA NA
NA NA
6.8 6.7
7.4 6.6
6.3 6.4
7.7 7.7
Large
yardage
. NA
NA
NA
6.8
4.2
4.0
7.7
Notes
NA
NA
a,b,c
a.d
e
"Plain suctton will be effective only In free-flowing sediments such as sands; unconsolidated silty, clayey, or organic sediments; and
liquids.
''Pneumatic systems that normally are operated in a plain suction mode could be operated with a variety of suction head devices such as
augers and cutters.
°Equipment can be land-based and/or operated from the shore.
Handheld vacuum will seldom be suitable as a first-line recovery device due to extremely limited production capacity. Probably will be
most useful for precise cleanup and peripheral operations; in situations of small, concentrated well-defined spills; and for cleanup in
close quarters. .. . • • •
•includes such equipment as backhoes, front-end loaders, dozers, draglines, and shovels varying in size from small farm tractor mounted
to large ship mining equipment.
NOTE: The numerical scores reflected in this table should not be contrued as an absolute measure of the dredge's value.
-------
TABLE 9. DREDGE EVALUATION MAIRIX; SPIU SCENARIO: RIVERS--ALL SPILL SIZES
Job .it. coay.til.illL>
\D
O
Uodlw.
s»ali l.eea- l.rg.
2ea.aea
>d* yd1 yd1
(7a6o*) (Ki.aea •))(>i6i,aee •
•oigntlng Factor a « a
Hoch.nl c.l
Dippor 7 6 1
Cl».holl a a 2
Hydr.ullc
Cutt.rho.d 17 9
(•nd pi. in
•uction)
Du.tp.n 17 9
Hopp.r 37 7
•n.unulic a 7 4
Othor
Uudc.l 96 2
H.ndn.ld v.cuui. 6 1 a
•C.n only b. u.od for . .olid conto.iln.nt unl...
°Pn.uift.tic ey.teeia th.t .re normally oper.ted In
Re.uapen-
•lon of
I Solid. .edinent. Dredging
Solid. .nd con- dopth
i1) content tw.ln.nt. ll.lt. lion
1
ia
la
6
1
6
7
a
2
•uction vlll .<
• Ing ..dliMnt.
• pi. In .uctlor
'Dredging depth, c.n bo effectively Incro.i.d »lth tho .dditlon
9£quip«ont c.n bo l.nd-b..od .nd/or operated fro*
tho .horo.
1 1
1 4
I ia
6 a
6 a
a a
7 ia
a i
a a
I effective only In free-f
•ucN .. ..no*., uncon.olld
i «ode could be operated o
of ouvlll.ry boo. tor puMp
V.X.I Dobri.
Tr.n.por-
Hln- t.tion
Holt.- tur.l to IUI- l.tlon So.ll Uodlw.
tlon eb.l.cle. traffic t.tlon tl«o y.rd.ge y.rd.ge
t 2
a 7
a 9
7 1
7 *
2 1
7 9
9 4
ia ia
1 1 3 NA NA
7 a 4 6.1 6.2
7 a 4 a. a a. a
J 7 2 4.1 6.4
172 4.1 6.4
994 4.* 6.1
i a a a. a a. 9
649 7. a 6.7
a i a a. a 6. a
loving aediinenta euch aa ..nd.( uncon.ol Id.ted altty, clayey, or organic aodlM
menta.
•ted .llty( cl.yey, or organic aedlmonto, end liqulda,
Ith a vorlety of auction head dovlcea auch aa ougora and cutter*.
a at the auction hood.
L.rg.
y.rd.ge Not.*»«
NA NA
3.9 >.b.g
4.' ..t-,4
a. a c,«,'
6.7 r
6.3 1
6.9 c.d.g
4.7 i
6.) e.h
int.; .nd liquid*.
''Handhold vaeuuo tvlll aoldoo bo aultablo a* a flrat-llno rocovory dovlco duo to ovtr**oly Ilialtod production capacity. Probably «lll b« moat utoful for proclao cloanup and
oporatlona; in aituatlona of a*»all. concontratod, »olI-doffood •pillaj and for cloanup In cloao quartera.
'Uudcat cannot bo uaod In opon vator aituatlona duo to aovoro dopth and vav* ho!0ht M*lfc»tlona but probably would b* awat offoctlv* In aittaM, nonnavl0*blo atroam*.
NOTE: Tho nmnorlcal vcoroa rofloctod In thl« tablo ahould not bo conatrwod aa an ab»olut» .Maauro of tho tfrodgo'a valuo.
por)ph«ral
-------
problem of assessing the suitability of a dredging technique. The same disad-
vantages are usually present (e.g., resuspension of the contaminant) regard-
less of the particular chemical. However, precautionary measures appropriate
to the specific chemical being recovered should always be diligently observed.
Also, the ratings do not take into account the problems of dredged material
transport, treatment and disposal. These factors may sometimes be found to be
controlling in selecting a system.
5.4.2 Wastewater Treatment Methods
5.4.2.1 Mechanical Removal—
The removal of PCB in primary sedimentation processes of sewage treatment
has been found to vary between 50 and 75 percent (Mclntyre, Perry, and Lester
1981). It would seem that, due to their nonpolar nature, the PCBs tend to
adsorb onto suspended solids and partition into fats and lipid material pres-
ent in the raw sewage. Sedimentation processes appear to concentrate the PCBs
into the sludges produced.
5.4.2.2 Activated Sludge-
Activated sludge methods do not apply directly to the decontamination of
PCB-contaminated sediments because their function is to remove contaminants
from wastewaters. They may be useful, however, as adjunct treatments where-
ever a sediment treatment process generates a waste stream that is aqueous and
contains dissolved PCBs. The processes have not been adapted to the immediate
problem of PCB degradation in nonaqueous media.
Wastewaters are subjected to aerobic-activated sludge treatment in con-
tinuously fed tanks where microorganisms digest and flocculate the organic
waste. The microorganisms (activated sludge) settle from the aerated liquor
in a final clarifier and are returned to the aeration tank. The purified
effluent is discharged from the final settling tank. Dissolved oxygen
extracted from the liquor is replenished by air sparged into the aeration
tank. The various engineering unit operations are sedimentation, aeration,
clarification, sludge dewatering, and chemical storage.
Using a continuously fed activated sludge unit, with a feed rate of
1 mg/48 h. Tucker et al. (1975) obtained the following degradation of PCBs:
91
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Aroclor 1221. 81 percent; Aroclor 1016, 33 percent; Aroclor 1242, 26 percent;
Aroclor 1254. 15 percent. The lower chlorinated isomers were shown to be more
readily degraded than the higher chlorinated isomers (Mihashi 1975). Mono-
chlorinated isomers were degraded 100 percent within 6 h; tetrachlorinated
isomers were degraded only 42 percent in 15 d. The major microorganisms found
in .the activated sludge were alkaligenes odorans, alkigenes denitrifleans, and
an unidentified type of bacterium.
5.4.2.3 Trickling Filter-
Trickling filters use crushed rock, slag, or stone to provide a surface
area for biological growth and passages for liquid and air. As the wastewate'r
flows over the microbial surface, the soluble organic material is metabolized
and the insoluble material is adsorbed onto the media surface. Biological
components of the filter may include bacteria, fungi, and protozoa. Nitrogen-
fixing bacteria are contained at the bottom of the filter.
A trickling filter consists of a rotary distributor, an underdraw system,
and the filter media. Because an aqueous flow medium is necessary, only
dilute soluble PCB isomers may readily be contacted with the active microbes.
No data were found relating specifically to the PCB-destruction performance of
trickling filters.
5.4.2.4 Special Biological Treatment Processes—
Several newer biological systems for the treatment of wastewaters are
emerging, none of which has been demonstrated for PCBs. These include the
Biodisc, a type of thin-film biodegradation system in which large plastic
discs are partially submerged in the aqueous waste solution. Aerobic
microorganisms colonize the disc surfaces and are oxygenated as the discs
rotate. This system creates a well-aerated surface requiring little space.
The Bio-Surf™ process creates anaerobic conditions by enclosing a sub-
merged Bio-Surf system and adding a carbon source such as methanol.
Ecolotrol, Inc., has developed a full-scale biological fluidized-bed proc-
ess, utilizing sand as the particle growth medium. A large population of
microorganisms is. generated, which makes possible a faster than conventional
treatment. A clarifier is not required (Wilkinson et al. 1978).
92
-------
A freeze-dried biochemical solution containing a mutant bacteria and vari-
ous substances to facilitate their growth has been shown by Worraes Biochemi-
cals to degrade various chlorinated hydrocarbons (Phenobac^M 1977).
5.4.2.5 UV/Ozonation—
PCB-contaminated wastewaters have been treated by ultraviolet radiation
combined with sparged ozone (Arisman and Musich 1981). In bench- scale tests,
the water was passed through a multistage reactor equipped with up to 30- to
40-watt low-pressure UV lamps. Ozone, generated from liquid oxygen, was dif-
fused into each stage. The treated effluents showed 91 to 100 percent
destruction of PCBs.
5.4.2.6 Carbon Adsorption—
Adsorption is useful for removing chlorinated hydrocarbons from aqueous
waste streams. The stream is contacted with activated carbon by passing it
through a vessel filled with a carbon slurry or with carbon granules. Impuri-
ties from the aqueous streams are removed by adsorption onto the carbon sur-
face. The complete adsorption system usually consists of a few columns used
as contactors connected to a regeneration system. After a certain period of
time, the carbon adsorptive capability is exceeded, and the carbon must be
regenerated or replaced by fresh carbon, which is also periodically added to
the system to replace that lost during regeneration and transport. Activated
carbon has an affinity for organics, and its use for organic contaminant
removal from wastewater is common. Carbon adsorption is particularly favor-
able when the solutes have a high molecular weight and low water solubility,
as is the case with dissolved PCBs. Carbon adsorption is one of the most
promising water treatment systems for removing dissolved PCBs, as indicated in
a study done by Versar, Inc.. in 1976. It was found in that study that the
activated carbon system was capable of reducing the concentration of PCBs in
the aqueous effluent to less than 1 ppb.
In 1976, the General Electric Capacitor Products Department installed a
system to eliminate the discharge of PCBs to the Hudson River from the Hudson
Falls and Port Edward manufacturing sites. All wastewater discharged from the
site was treated by carbon adsorption before the discharge to the river. This
adsorption process worked extremely well for dilute aqueous streams contami-
nated with PCBs. It was found that, while the carbon treatment system could
93
-------
reduce the concentration of PCBs in the aqueous effluent to less than 1 ppb,
it was not a very cost-effective method. This, coupled with carbon disposal
or regeneration requirements, provided a basis for the EPA and the General
Electric Capacitor Products Department to investigate alternate treatment
systems, i.e., UV-ozonation and catalytic reduction (Arisraan 1981).
Results of adsorption treatment of water polluted with PCB (Aroclor 1260)
have also been reported by Gilmer and Freestone (1978). Using sand filtration
and carbon adsorption, PCB concentrations of approximately 19 g/mL were
reduced to less than 0.05 to 0.2 g/mL. The authors also used the Mobile
Physical-Chemical Treatment System (EPA Edison) to treat impounded water con-
taining 85 g/mL of PCB. Using bag filters and carbon adsorption, the concen-
tration was reduced to 4.5 g/mL after the bag filters and to <0.2 g/mL after
carbon adsorption. The overall treatment effectiveness amounted to 99 percent
removal.
I
-------
SECTION 6
CHARACTERIZATION AND RANKING OF
ALTERNATIVE TREATMENT PROCESSES
This section provides two comparisons of the alternative treatment proc-
esses assessed in Section 5: characterization and ranking. The characteriza-
tion provides for objective comparison of the processes. The ranking provides
a subjective comparison of the processes based on the seven criteria described
in Section 4.
6.1 CHARACTERIZATION
Table 10 summarizes five characteristics of the processes: unit opera-
tions, available capacity, conditions/limitations, concentration handled, and
any generated RCRA wastes. The unit operations employed are given, and each
is identified by a number. Generally, a greater number of unit operations
will mean a greater effect on treatment costs.
None of the processes has currently available capacity approaching that
required for major cleanups. Therefore, the time required to build capacity
is listed. Construction time ranges from 12 to 24 months.
Certain conditions that typify the process or limit its versatility are
given in column 4 of Table 10. More details of the operations are given in
Section 5.
The data from studies of the processes were examined for ranges of PCB
concentrations handled to date. Generally, the values are not limitations on
the process, but only on the data acquired. The value <300 ppm for the
Bio-Clean process may, however, be a limitation requiring process adjustment
to control.
95
-------
TABLE 10. TREATMENT PROCESS ASSESSMENT
Process
Unit
operations
Available
capacity
(or time
to provide)
Conditions
and limits
Concentration
handled
RCRA
waste
generated
Chemical
Supercritical water oxidation
1.4.10
KP8G, Terraclean-a
KPEG. NYU
KPEG, EPA in-houseb
LAfiC
Advanced electric
reactor (J. M. Huber)
ical
0. H. Materials
methanol extraction
'Soilex' kerosene/water
Acurex solvent wash
Vitrification
1,3,4.7 (24 •>)
1,2.3.4,5, ~
5.7.9
Fundamental studies
1.2.5.15, (24 mo)
7,8,12,13 (16 mo)
14
2.7.8.14
15
1.2.5.15
2.4,5.6.
10,11
8.12,14
20-40% solids; 374 °C, >3000 ppra
23.3 MPa organic
content >5% or supple-
mental fuel
150 °C, 0.5-2 h
500 ppro or
greater
tolerates 25% water.
480 ppnt
2204 °C, 2,400 kWh/m3 >3000 ppm
needs predryer
predry to <1% moisture >400 ppm
25% of kerosene sol- to 350 ppm
vent retained in soil; tested
3 d per batch
3-12 washes, tolerates up to 1,983
<40% water. ppm
Electrical power usage 500 ppm
increases with soil
moisture; submerged
sediments dredged
and treated
None
w.w.tr.
act.
carbon
None
None
PCS-loadeci
carbon from
solvent
cleanup
Concentrat-
ed PCS fran
still to
incinera-
tion
Concentrat-
ed PCB's to
KPEG
None
(continued)
96
-------
TABLE 10 (cmtinued)
Process
Unit
operations
Available
capacity
(or tine
to provide)
Conditions
and limits
Concentration
handled
RCRA
waste
generated
Biological
Congesting
Bio-Clean
Sybrcn Si-Cham 1006
15,16
1.2,17
15,17
(16 no)
Seasonal effects,
reaction tine must be
>4 weeks
1,590 pan
27 md avail- Proved for PCP. labor- i300 pom
able, 12 mo for atory confirmed for
full-size PCB's
Unknown
Unknown
Treated
material
is still a
RCRA waste
None
Unknown
NOTE-Unit operations key:
1. Liquid/solids separation
2. Extracticn/solubilization (liquid-solids)
3. Liquid/liquid extraction
4. Chemical reactor
5. Stripping still :
6. Solvent recovery still
7. Adsorption
8. Dryer (solids)
9. Dryer (liquids)
10. Filtration
11. Steam cleaning
12. Thermal reactor
13. Grinding
14. Air pollution controls
15.. landfarm
16. Inrcculation/digesticn
17. UV light reactor
97
-------
Table 10 also identifies any RCRA waste streams generated by the process.
Possible treatments of some of these are discussed in Section 5.
Table 11 lists five additional characteristics of the processes and the
rating developed in the ranking process. The characteristics shown here
relate to the needs for further process development, listing, and evaluation.
The listing begins with an indication of the process status in terms of stages
of development completed. The processes range in stages completed from con-
cept to pilot plant.
Both PCB destruction and residual PCB concentration in treated sediments
are given to the extent available. Certain processes may require extension of
the unit operations (e.g., more stages of extraction) to attain the required
performance levels.
Test and evaluation data needs are indicated for each process. Needs vary
from none (AER process) to complete site-specific evaluation.
The estimated costs of applying the process are listed in $/m^. Thes« are
displayed in Figure 16. Landfill costs and incineration costs are also shown.
Although cost estimates lack the necessary accuracy at this stage of develop-
ment of the alternative processes to serve as the sole criterion of potential,
they nevertheless indicate that seven of the processes may cost no more than
landfill and five could cost less. (Cost estimates were not made for the
Sybron process and composting.)
6.2 RANKING OF TREATMENT PROCESSES
In contrast to process characterization, ranking is subjective. An
attempt was made to define and determine a single number that could represent
the overall position of each process relative to an arbitrarily defined per-
fect process. To do so, factors considered were given ratings as described
below.
98
-------
TABLE 11. TREATMENT PROCESS ASSESSMENT
Estimated Estimated
0/0/R residual Test and evaluation Estimated
Process Status3 efficiency, %b PC8, ppm data needs costs, $/m3 Rating0
Chemical/physical
Supercritical water Field test with
oxidation, Modar PCS liquids
>99.9995
1,2,3,4.5,6.7, 250-733
4.58
KPEG Terraclean-a Pilot tests
>98
ppm
1,6
208-375
5.42
LAfiC
Lab tests
>90
33-50
2,3.4.5.6,7
223-336
5.26
Advanced electric Pilot tests
reactor
>99.9999
ppb
Noned
830-943
4.58
Physical
0. H. Katerials, Field tests under
methanol extraction way
97
<25 ppm
2.3,6.7
401-514
4.16
Soilex
Pilot tests
95 6-9 ppm
(3 stages)
5.6,7
856-913
3.25
Acurex solvent wash
In-situ vitrification
Battelle Pacific
NWforEPRl
Pilot-scale e
(field tests
planned)
Pilot test of soil 99.9
<2ppm
None in vitri-
fied block, 0.7
ppn in adjacent
soil
Identity of 196-569
mixed solvent.
6.7
6 255-548
. 5.21
1.53
See footnotes at end of table.
(continued)
99
-------
Tj»BLE 5 (continued)
Process
Status3
Estimated Estimated
0/0/R residual
efficiency. %*> PCS. ppm
Test and evaluation Estimated
data needs costs, $/nr^ Rating0
Biological
Composting, aerobic Lab-scale
anaerobic Lab-scale
62
18-47
504-908
325-1268
4,5,6
4.5,6
— 2.47
— 2.47
Bio-Clean, aerobic Bench-scale
99.99
25ppb
3,5,6,7
191-370
4.84
Sybron Si-Chen 1005 Lab-scale and concept 50
3.4,5,6,7
1.48
NOTE—Data needs key:
1. 0/0/R data
2. Residual PCS data
3. Unit operations data
4. Bench-scale data
5. Pilot-scale data
6. Field test data
7. Cost data
8. RCRA waste
Status is defined in terms of the types of studies completed.
^O/D/R = destruction/detoxificaticn/removal.
°rhe rating was obtained as shown by the example, under Characterization.
dAER is fully permitted under TSCA in EPA Region IV for destruction of PCS.
treatment is continued until a residual of <2 ppm PCS's is obtained.
100
-------
Landfill
kPEGT
Sup. Crit. Water
Adv. Elec. Reac.
MeOH EM.
Sottex
Acurex
Vitrification
Bio-Clean
LARC
Incineration
Cost, $/m3
ro
J
til
o
M
U1
O
01
o
ro
o
o
o
Figure 16. Alternative treatment costs, PCB D/D/R processes.
-------
6.2.1 Residual PCB Concentration in Treated Sediments
The goal set for process performance is to reduce the PCB concentration in
treated sediments to background levels of 1 to 5 ppra. Several of the proc-
esses were found to meet this goal. Those that showed reduction to less than
2 ppra were assigned a rating of "6". Those that attained a level between 2
and 10 ppm were assigned a "4". Those with residual concentrations greater
than 10 ppm were rated "2".
6.2.2 Available Capacity
Available capacity was found not to exist for any of the processes. How-
ever, several were developed sufficiently to permit projections of the time
required to build a facility for application of the treatment. Those for
which such projections could not be made were rated "2". Those requiring 24
or more months were rated "4". Those requiring 12 to 16 months were rated
"6".
6.2.3 Conditions/Limitations
Conditions/limitations that were rated were tolerance for water, required
processing time, and controllability of process conditions. Those treatments
that could tolerate water up to about 40 percent would not require a drying
step with its attendant fines control problems. Those requiring only 1 day
for treatment could generally show a faster rate of cleanup than those
requiring 3 days. Some biological processes required more than 3 weeks. The
treatments generally provided control of the processing conditions; however, a
few (e.g., composting) would not necessarily do so. The three conditions/
limitations were ranked as follows:
Conditions/limitations Rank
Tolerates to 40 percent water and treats in 1 day 6
Sediment needs to be dried - g
Tolerates to 40 percent water and treats in 3 days 4
Tolerates water and;treats in >3 weeks 3
Sediment needs to be dried, treats in >3 weeks 2
Processing conditions uncontrollable 1
102
-------
6.2.4 Concentration Range Handled
Concentration range handled in data developed for the processes ranged
from unknown to 3.000 ppra. Ratings were assigned based on the upper limit of
feed concentration. The ratings were as follows:
PCB concentration treated, ppra Rank
>3,000 6
2,000 to 3,000 5
1,500 to 2,000 4
500 3
250 to 350 2
Unknown '. 1
\
6.2.5 Status of Development
Status of development ratings were "1" for no data, "2" for laboratory-
scale tests completed, "3" for bench-scale tests completed, "4" for pilot-
scale tests completed. "5" for field tests completed: and "6" for commercial
system designed and ready for construction.
6.2.6 Test and Evaluation Data Needs »
Test and evaluation data needs could be rated differently, depending upon
the purpose. For indicating the extent to which a treatment process is
readied for use, the more data that are available the better. For indicating
the need to support a very promising technology that lacks sufficient prog-
ress, the potential and the data needs should be rated in combination. The
ratings used here are for the former purpose and are as follows:
Test and evaluation data
None except permits and checkout 6
Field tests
Pilot tests and costs
Laboratory and bench tests
needs Rank
5
4
3
Conceptual treatment process design 2
D/D/R data, residual PCB data, RCRA waste data 1
103
-------
6.2.7 Estimated Costs
Estimated costs were assembled graphically (Figure 16). The estimates
were then rated by comparing the range of the cost estimates obtained with the
cost of placing them into a chemical waste landfill. Treatment processes
showing the lowest estimated cost range were rated "6": those showing a prob-
able cost lower than landfill were rated "4"; those showing an estimated cost
equal to landfill were rated "2"; and those showing an estimated cost range
greater than landfill were rated "1".
6.2.8 Overall Ranking
Overall ranking was accomplished through the use of weighting factors
assigned to each rated factor. The weighted average rank was then obtained by
summing the products of the weighting factors and the ratings and dividing by
the sum of the weighting factors. The weighting factors were:
Factor Weight
Residual PCB concentration 5
Capacity 2
Conditions/limitations 3
Concentration range handled 2
Status of development 2
Test and evaluation data needs 1
Estimated costs 4. .
The weightings tend to give greatest emphasis to the ability of the treat-
ment to reduce the PCBs and to the probable cost of the treatment. Much less
emphasis is placed on the status of development. Thus, an almost fully
developed process with an extremely high cost would be ranked lower by appli-
cation of the weighting process than a less developed process with a much
lower potential cost. Test and evaluation data needs have not been heavily
weighted because nearly all the alternative treatment processes that show low
potential cost require more data to be proven.
The perfect process for treating PCB-decontaminated sediments would show
the following levels for each ranking factor and would receive, using the
ratings given, a weighted rating of 6.0:
10U
-------
Factor level
1. Residual PCB, treated sediment
less than 1 ppm
2. Capacity adequate for site
cleanup available in 12-16 mo.
3. Tolerates to 40 percent water
and treats in 1 day (24 hr)
4. Handles concentrations greater
than 3,000 ppm
5. Commercial system designed and
ready for construction
6. No test and evaluation data
needs except permits and checkout
7. Lowest estimate cost range among
alternative emerging technologies
Total R x Wt £ R x Wt
Weighted rating (£ R x Wt)/£Wt
Rating. R Wt R x Wt
30
12
18
12
12
24
114
6
The weights were assigned subjectively to emphasize low residual PCB. then
estimated cost and water tolerance. The weights were used as multipliers to
give the chosen emphasis.
This procedure established a range of 1.48 to 6.0 for the weighted rating.
Under this procedure, one process just emerging, without a fully developed
concept of its operations and with very limited data available for evaluation,
received a weighted rating of 1.48. The further developed processes received
ratings up to 5.42 (Table 12). The difference (6 to 5.42) is a subjective
indication that further research would be productive in regard to all these
criteria considered collectively. Scores assigned for each factor are also
listed in Table 12. The weighted ratings show two ties at 4.58: Supercriti-
cal Water, and the Advanced Electric Reactor.
Based on the weighted ratings, the processes rank as follows from highest
to lowest: KPEG. LARC. Acurex.. Bio-Clean, Modar-Supercritical Water, Advanced
Electric Reactor, Vitrification, OHM Extraction, Soilex, Composting, and
Sybron Bi-Chem 1006 PB/Hudson River Isolates.
105
-------
TABLE 12. RANKING OF EMERGING TREATMENTS FOR PCS-CONTAMINATED SEDIMENTS
o
ON
Factor
relative
weight
Residual PCS 5
Available capacity 2
Conditions limitations 3
Concentration range handled 2
Status of development 2
Test and evaluation data
needs 1
Estimated costs . 4
Weighted rating
Supercritical
water, Modar
6
2
6
6
3
1
4
4.58
KPEG
Terraclean
6
4
6
5
4
5
6
5.42
Advanced
electric
reactor
6
6
5
6
4
6
1
4.58
0. H.
Materials
extraction
6
6
5
5
4
4
2
4.16
Soilex
4
2
4
5
4
4
1
3.26
Acurex
6
2
6
5
4
5
6
5.21
Vitrification
6
4
5
6
4
5
2
4.53
Composting
2
2
1
3
2
3
1
2.47
8io-Clean
6
6
4
2
3
4
6
4.84 .
Sybron
Bi-Chem
1006
2
2
1
1
2
1
1
1.48
LARC
6
4
6
5
3
4
6
5.26
-------
SECTION ?
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