United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-87/093 Jan. 1988
&EPA Project Summary
Report on Decontamination of
PCB-Bearing Sediments
Donald L.Wilson
Polychlorinated biphenyls (PCBs)
exist as contaminants in sediments
throughout the country. Conventional
and emerging waste management
methods have not addressed
decontamination of these sediments.
EPA has initiated a program to
identify chemical/biological methods
as alternatives to incineration and
chemical land disposal for cleanup
of PCB-contaminated sediments.
The overall objective of the program
is to identify, validate, and
demonstrate effective and
economical chemical/biological
processes for removal/destruction of
PCBs in sediments. This report
summarizes progress on
chemical/biological methods for the
detoxification/destruction of PCBs in
sediments.
This Project Summary was
developed by EPA's Hazardous Waste
Engineering Research Laboratory,
Cincinnati, OH, to announce key
findings of the research project that
is fully documented in a separate
report of the same title (see Project
Report ordering information at back).
Introduction
Polychlorinated biphenyls (PCBs)
were widely used as a dielectric fluid in
transformers and capacitors as well as in
hydraulic and heat-transfer fluid
systems because of their stability and
heat resistance. During the 50 years that
PCBs were manufactured and used in
this country, an estimated 400 million
pounds of these chemicals entered the
environment. Because of the broad use
of PCBs (ranging from transformer
dielectric oils to carbonless paper
production), they are widespread in the
modern environment, especially the
aqueous environment.
Although PCBs are a suspected
carcinogen, their acute toxicity is
considered to be non to slightly toxic by
the LD50 Method. A more significant
health impact has been linked to the
incomplete combustion (burning) of
PCBs. Under certain circumstances,
oxidation of PCBs form dioxins and
furans, most toxic of all man-made
substances. While PCBs have long been
known to be toxic, they have only
recently been acknowledged to be a
general threat to the environment. The
characteristics that made PCBs such a
problem is their stability and therefore,
persistence in the environment. These
chemicals have been found in
measurable concentrations in waterways
and sediments through the world and are
widely spread contaminants of fish and
wildlife resources. PCB contamination
began in an era when industrial wastes
were disposed of by flushing them
directly into waterways, local sewage
plants or landfills.
The PCB contamination problems in
New Bedford, Massachusetts (EPA
Region I), the Hudson River in New York
(EPA Region II), and in Waukegan, Illinois
(EPA Region V) are reported to be the
worst in the United States in terms of
concentration and total quantity of PCBs.
It is estimated that 290,000 kg of PCBs
are contaminating 382,000 m3 (500,000
yd3) of sediments of the Hudson River.
During the 1970's approximately 907,000
kg of PCBs were used in the New
Bedford area annually, of which an
estimated 45,500 kg were improperly
disposed. Also, there are many industrial
lagoons contaminated with large
quantities of PCBs. For example, EPA
Region III reports three sites in
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Pennsylvania and two in West Virginia
where over 3200 m3 (2447 yd3) of
soil/sediments are contaminated with
PCBs. The RGBs contamination
problems pose threats to both drinking
water and the fishing industry.
The only available proven
technology is dredging and expensive
incineration. Land disposal of the
untreated sediments has legal
restrictions. Biodegradation is a
possibility, but sufficient information does
not exist to design and operate such a
system There is little experience in the
application of encapsulation technology
to PCB-contammated sediments.
Although a great amount of work has
been done by many research groups in
the area of PCB-contaminated liquids,
relatively little effort has been directed
toward PCB-contaminated sediments
and sludges. The EPA Regional and
Program Offices are being asked to
comment on the technical and economic
feasibility of chemical/ biological
processes for cleanup of these
sediments and sludges These Offices
do not have adequate data to
recommend any of a number of
processes proposed or being
tested/evaluated for the decontamination
of sediments containing PCBs.
Assessment of Processes
Because there is little known about
the application of chemical and biological
processes to the decontamination of
PCBs m sediments, Research Triangle
Institute (RTI) was engaged by EPA to
undertake a study 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 development,
effectiveness, limitations and probable
costs, and to determine needs for their
further development. The study involved
three phases: identification of the most
promising processes and their further
development needs, evaluation of the
unit operations involved in the processes
against engineering, health, and
environmental criteria for further testing
and evaluation; and definitive
assessment of the recommended
treatment processes using pilot systems
and contaminated sediments
The first phase involved four steps:
data acquisition, screening and selection
of most technically feasible processes,
development of criteria for process
assessment, and process assessment.
Under step one, three major sources of
data were: EPA's file of proposals and
correspondence concerning problems of
PCB contamination and possible
approaches to alternative solutions; the
open literature; and direct contacts with
proponents of treatment technologies. In
step two, the processes were
categorized according to their generic
technology so that their potential
performance could be judged
appropriately. Processes with
undesirable aspects, for example lack of
tolerance for water, were rejected from
further assessment. Criteria for
assessment, step three, were chosen
which relate to a broad range of
principles of operation of diverse applied
technologies, yet can be used effectively
in comparing one treatment process with
another. Additional factors, specific to a
technology, were included to help
portray the inherent strengths and
limitations of a process. The seven
criteria used and three additional factors
were: estimated residual PCB; available
capacity; conditions/limitations; con-
centration range handled; status of
development; test and evaluation data
needs; estimated cost; unit operations;
RCRA waste generated; and estimated
destruction/detoxification/removal ef-
ficiency. In the final step, the processes
were assessed by characterization and
ranking. Characterization provided for
objective comparison of the processes.
Ranking provided a subjective
comparison of the processes based on
the seven criteria.
In the first phase, eleven emerging
alternative treatments of the sixty-four
processes considered for PCB-
contaminated sediments were compared
and ranked. Eight candidate treatment
processes showed potential as
alternatives to chemical waste landfill and
to incineration. Some had been tested on
soils but none were tested specifically on
PCB-contaminated sediments.
Sediments of concern differ from soils in
several properties that influence the
performance of unit operations involved
in the treatment processes.
The second phase built upon the
first phase of the assessment so that
EPA may have more complete
information before evaluating any
technology in the field. This second
phase involved three steps: consulting
with the treatment process developers,
technical assessments of the process,
and the selection of three of the
processes for thorough test and
evaluation Consultations included visits
to the developers' facilities where further
information was developed. The most
recent performance data were reviewed.
The availability of the system was
determined. The visits included
checklist of needed information a
criteria for assessment of the process'
The technical assessment was bas
upon the projection of the performan
and cost of a large-scale treatrm
system of sufficient capacity to treat
estimated 380,000 m3 Of PC
contaminated Hudson River sediments
2.5 years. Specific sample data frc
Hudson River sediments were used
guide the projection of operati
conditions required for treatment by ea
process assessed. The processes w<
compared and rated using the results
the assessment. Based on compos
ratings, three processes showing t
highest rating were recommended
test and evaluation.
The objective of the proposed th
phase is to provide EPA with a defensit
thorough test and evaluation of the thr
alternative treatments selected in Pha
2. In carrying out this phase, EPA v
arrange to have PCB-contaminat
sediments treated in pilot-sea
processing systems selected in Phase
The pilot tests will evaluate performan
under field conditions, and will
supported by laboratory test
Confirmation of treatment proce
effectiveness will make these process
very viable and cost-effective metho
of treating these hazardous wastes.
The following processes we
studied by RTI on Phase 2 of the study
B.E.ST.
The Basic Extraction Sludi
Treatment (B.E.S.T.) process w
developed by the Resourci
Conservation Co. (RCC) 3101 N.
Northup Way, Belleview, WA 98004. T
process uses a solvent having an inver
critical solution point in water to remo
water and oily material from solid matt'
It has been applied to cleanup of PC
contaminated oily sludges at a CERCI
site (Savannah, Georgia).
Ultrasonics/Hydrogen •
Ozone/UV Technology
The process is based up<
simultaneous extraction and treatment
a sediment slurry with ultrasound (abo
20KHz) added to increase rates
dissolution of the PCB contaminants a
reduce coalescence of bubbles of g
reactants The treatment is achieved
either ozone/ultraviolet irradiation
hydrogen/ultraviolet irradiation. Tl
sediments are fed as a slurry containi
about 20 wt. percent solids into a mixi
tank where predetermined amounts
detergent and sodium hydroxide a
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added. The conditioned mix is pumped
o the reactor where the solids are
maintained in suspension while the
mixture is exposed to ultraviolet
irradiation and ozone (or hydrogen) is
added. During this treatment,
microscopic turbulence is produced
through ultrasonics. The treated slurry is
fed into a cyclone where the solids are
removed, sampled, and tested to certify
them for discharge. The separated water
is neutralized and also tested before
discharge.
Bio-Clean Naturally-Adapted
Microbial
The Bio-Clean Naturally-Adapted
Microbial process has been developed
by Bio-Clean, Inc. Bio-Clean is a
company engaged in developing process
systems to clean up, remove or destroy
hazardous chemicals in the environment.
The process utilizes Arthrobacteria sp
and/or other naturally-adapted microbes
to destroy PCBs (and related organics)
under aerobic conditions.
KPEG with DMSO
Nucleophilic substitution with the
KPEG process and the Galson Research
version (Terraclean-CI process) was
looked at as a means of decontaminating
PCB-bearing sediments. The potassium
polyethylene glycolate (KPEG) process
has two potential applications in the
treatment of PCB-contaminated
sediments: the treatment of the
sediments themselves, or the treatment
of concentrated PCBs resulting from
extraction processes. The former is
assessed in terms of the Galson
Modified KPEG process, that is, with
dimethyl sulfoxide (DMSO). The latter
application would require treatment of a
relatively concentrated solution of PCBs
in a non-aqueous solvent (triethylamine,
kerosene, etc.).
CFS Propane Extraction
The CFS Propane Extraction Process
is a technology available from C. F.
Systems Corporation, 25 Acorn Park,
Cambridge, Massachusetts 02140. The
company is a subsidiary of Arthur D.
Little. As applied to PCB-contaminated
sediment, the process uses propane at
ambient temperature and 1378 kPa (200
Ib/in2) to extract PCBs along with other
oily organics from a water slurry of the
sediment. The treated slurry is
discharged after separation from the
liquid propane which contains dissolved
contaminant. The propane solution is fed
to a separator where the solvent is
removed by vaporization and recycled.
The contaminants are drawn off as a
concentrate for final treatment. The
process has been tested for PCB-
contaming refinery sludge. The PCB
content of the solids component of the
sludge was reduced to 5 ppm.
Modar Supercritical Water -
Oxidation
This process has been developed by
MODAR, Inc., 3200 Wilcrest, Suite 220
Houston, Texas 77042. The process
utilizes water above critical conditions
(374°C and 22.1 MPa) to increase the
solubility of organic materials and
oxygen and effect a rapid oxidation,
destroying organic contaminants. It has
been applied to destroy PCBs in oils,
and to decontaminate dioxin tainted soil.
The company has a laboratory test unit
and skid-mounted pilot test unit having
a nominal organic material flow capacity
of 190 liters/day. This unit has been
operated at MODAR's research facility in
Natick, Massachusetts and at the
CECOS International Niagara Falls site.
In Situ Vitrification
In Situ Vitrification was previously
discussed as a process developed to
treat radionuclide-contaminated wastes,
and subsequently tested for possible
adaptation to the treatment of PCB-
contaminated soils. Submerged
sediments would be dredged before
treatment. The process stabilizes
contaminated soils by melton into a
durable glass and crystalline form. Four
electrodes are inserted into the
sediments in a square array. A path for
electric current is made by placing a
mixture of graphite and glass frit between
the electrodes. Dissipation of power
through the starter materials creates
temperatures high enough to melt a layer
of sediment, which establishes a
conductive path. The molten zone grows
downward through the contaminated soil.
At the high temperatures created
(<1700°C), organic materials pyrolyze,
diffuse to the surface, and combust.
Off-gases are collected, monitored, and
treated.
Solvent Extraction Process
In a separate study, scientists at the
New York University's Department of
Applied Science have been carrying on a
three year EPA supported investigational
program on the development and
evaluation of a low energy process
technology for the solvent extraction and
subsequent chemical destruction of
PCBs from contaminated sediments and
sludges. This is also one of the
processes which was assessed by RTI in
Phase 2. This program involves
experimental studies on potentially more
cost-effective PCB disposal alternatives
to currently accepted practices. The
research activities during the first year of
this program comprised the investigation
of suitable solvent extraction and
supporting equipment, identification of
candidate solvents for extraction and
concurrently developed application and
verification of analytical methodology for
quantitative determination of PCBs in
contaminated sediments. Exploratory
experiments were also carried out on the
extraction of PCBs from contaminated
sediments obtained from Waukegan
Harbor, Illinois.
The concept of using kerosene as an
extraction solvent for removing PCBs
from sludges and sediments was based
on two factors: (1) the low cost of
kerosene and (2) some work conducted
on extraction of PCBs from soils (M. B.
Saunders at Oak Ridge National
Laboratory, 1985) While the cost factor
is a driving force in any development, it
alone cannot overcome technical
impracticahties. It became quite evident
early in this study that the presence of
large quantities of water in the
contaminated samples presented an
insurmountable barrier to the use of
kerosene in this application. A new
approach to this difficult problem was
needed and is herein presented.
The first step of the process takes
advantage of the extremely low solubility
of PCBs in water In a typical PCB-
contaminated sediment or sludge
composed primarily of water with
generally 20% total solids, virtually all of
the PCBs are associated with the
sediment. Thus, the first processing step
is a physical separation of water and
solids. In the second step, the PCB-
contaminated oil is dissociated from the
sediment substrate This is accomplished
by a multi-stage counter-current
leaching with a hydrophyllic solvent. The
third step is a stripping operation in
which the PCB-containing stream from
above is contacted m a liquid-liquid
extractor with a hydrophobic solvent and
additional water The two streams which
leave this step are the PCBs
concentrated in stripping solvent which
proceeds to appropriate methods for final
destruction, and the hydrophyllic
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solvent/water mixture containing trace
PCBs. The solvent/ water mixture goes
next to a distillation column in which the
solvent is separated and returned to the
leaching process. The water
contaminated with trace amounts of
PCBs is recycled to the front of the
stripping process to close the cycle
Conclusions
Various experimental and supporting
activities were carried out during the first
year of the EPA-supported research in
order to develop an adequate data base
for achieving an effective low energy
process for the extraction of PCB's from
contaminated sediments and sludges.
Achievements from these investigations
are summarized as follows:
1 Selection of extraction and
supporting equipment for a
specific extraction,
2 Identification of candidate
solvent systems for extraction.
3 Development of an appropriate
analytical methodology for the
determination of PCBs in
contaminated sediments and
sludges
4 Development of an innovative
process scheme for the
extraction of PCBs from
sediments and sludges
Emerging treatment processes for
decontamination of sediments containing
PCBs that show potential as alternatives
to incineration and chemical waste
landfill have been identified in Phase 1 of
an assessment study. Eleven alternative
treatments were compared and ranked
using technical performance, status of
development, test and evaluation data
needs, and cost as factors. The first eight
processes show potential for reduction of
PCB concentrations to the desired
background levels (1-5ppm) or less,
with minimum environmental impacts
and low to moderate cost. The sediments
must be dredged for application of these
treatments. Based on the weighted
ratings of Phase 1, eleven processes
ranked as follows from highest to lowest.
KPEG, LARC, Acurex, Bio-clean,
Modar-Supercntical Water, Advanced
Electric Reactor, Vitrification, OHM
Extraction, Soilex, Composting, and
Sybron Bi-Chem 1006
At the start of the final assessment
study before field tests, some former
developers indicated their processes
should not be considered, and some new
processes became available. Thus, in the
next assessment study-Phase 2, eight
emerging treatment processes for
decontamination of PCB-contaminated
sediments were evaluated as candidates
for thorough test and evaluation using a
test system of sufficient size to provide
performance, cost, and scale-up data
for a large commercial plant. The
processes assessed and listed in relative
desirability of test and evaluation include:
(1) Basic Extraction Sludge Treatment
(B.E.S.T.) developed by Resources
Conservation Co.;(2) UV/ Ozone or
Hydrogen/Ultrasonics Technology of
Ozonic Technology, Inc.; (3) Bio-Clean
Naturally-Adapted Microbial Process of
Bio-Clean, Inc., (4) KPEG (Galson)
Process modified by Galson Research
Corp.; (5) Low Energy-Acetone-
Kerosene Extraction Process developed
by the Applied Science Dept. of New
York University; (6) Modar Supercritical
Water Oxidation Process of Modar, Inc.;
(7) CFS Propane Extraction Process of
C. F. Systems and (8) In-Situ
Vitrification Process by Battelle Pacific
Northwest Research Laboratories.
Recommendations
While all the processes except In Situ
Vitrification appear to merit further
development for this application, those
three with the highest comparative
ratings are recommended for EPA-
supported thorough test and evaluation.
These are the Basic Extraction Sludge
Treatment, UV/Ozone or Hydrogen/
Ultrasonics Technology, and Bio-Clean
Naturally-Adapted Microbe processes.
There is, in an evaluation of processes
such as this, much uncertainty.
Additional research of the other
processes is very important to fill in the
data gaps The other processes, for
example, may be more cost effective on
a smaller scale than what the study
assumed or with other unit processes.
The results of the EPA funded study at
the New York University have led to a
novel approach to treatment of PCB-
contaminated sediments and sludges. It
is recommended that a study is needed
to model, engineer and otherwise fully
characterize this process so that its full
potential might be realized.
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The EPA author Donald L. Wilson (also the EPA Project Officer, see below) is with
Hazardous Waste Engineering Research Laboratory, Cincinnati, OH 45268.
The complete report, entitled "Report on Decontamination of PCB-Bearing
Sediments, "(Order No. PB 88-113 2201 AS; Cost: $14.95, subject to change)
will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Hazardous Waste Engineering Research Laboratory,
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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