PxEPA
United States
Environmental Protection
Agency
Research and
Development
(RD681)
EPA/540/A5-91/003
February 1992
BioTrol Soil Washing
System for Treatment of a
Wood Preserving Site
Applications Analysis Report
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
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EPA/540/A5-91/003
February 1992
BioTrol Soil Washing System
for Treatment of a
Wood Preserving Site
Applications Analysis Report
Risk Reduction Engineering Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268
Printed on Recycled Paper
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Notice
The information in this document has been funded by the U.S. Environmental
Protection Agency under the auspices of the Superfund Innovative Technology
Evaluation (SITE) Program under Contract Nos. 68-03-3485 and 68-CO-0048 to
Science Applications International Corporation. It has been subjected to the Agency's
peer and administrative review, and it has been approved for publication as an EPA
document. Mention of trade names or commercial products does not constitute an
endorsement or recommendation for use.
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Foreword
The Superfund Innovative Technology Evaluation (SITE) Program was autho-
rized in the 1986 Superfund Amendments. The Program is a joint effort between
EPA's Office of Research and Development and Office of Solid Waste and Emergency
Response. The purpose of the program is to assist the development of hazardous waste
treatment technologies necessary to implement new cleanup standards which require
greater reliance on permanent remedies. This is accomplished through technology
demonstrations designed to provide engineering and cost data on selected technolo-
gies.
This project consisted of a demonstration of BioTrol, Inc.'s sequence of three
processes for treatment of contaminated soil. It consists of (1) soil washing to wash and
segregate coarse, relatively uncontaminated soil from more heavily contaminated
fines; (2) biodegradation of the organic contamination on the soil fines in a slurry
bioreactor; and (3) fixed-film, amended biological treatment of process water recycled
in the soil washing operation. Extensive analysis was used to assess the effectiveness
of each stage in the system. The study was carried out at the MacGillis and Gibbs
Company site in New Brighton, Minnesota, where wood preserving operations have
been carried out over several decades using the traditional wood preserving chemicals:
first creosote, later pentachlorophenol, and most recently, chromated copper arsenate.
In 1984 the site was added to the National Priorities List as one where soil and
groundwater were contaminated with hazardous chemicals. The goals of this study
were to evaluate the technical effectiveness and economics of a treatment process
sequence to concentrate and then eliminate pentachlorophenol and polynuclear
aromatic hydrocarbons from contaminated soil and to assess the potential applicability
of the process to other wastes and/or other Superfund and hazardous waste sites.
Additional copies of this report may be obtained at no charge from EPA's Center
for Environmental Research Information, 26 West Martin Luther King Drive, Cincin-
nati, Ohio 45268, using the EPA document number found on the report's front cover.
Once this supply is exhausted, copies can be purchased from the National Technical
Information Service, Ravensworth Bldg., Springfield, VA, 22161, 703-487-4600.
Reference copies will be available at EPA libraries in their Hazardous Waste Collec-
tion. You can also call the SITE Clearinghouse hotline at 1-800-424-9346 or 202-382-
3000 in Washington, D.C. to inquire about the availability of other reports.
E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory
ill
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Abstract
This project was an evaluation of the gioTrol, Inc. Soil Washing System (BS WS),
consisting of aproprietary mechanical soil washer andseparation system, aSlurryBio-
Beactor (SBR) provided by EIMCO Process Equipment Co., and BioTrol's propri-
etary Aqueous Xreatment System (BATS), a fixed-film, aerobic biological treatment
process. In this study, both biological processes use bacterial populations selected to
specifically degrade pentachlorophenol (penta).
This report summarizes and analyzes the results of the Superfund Innovative
Technology Evaluation (SITE) Program's demonstration at the MacGillis and Gibbs
Company wood preserving site in New Brighton, MM during the Fall of 1989.
Extensive sampling and analysis were carried out to establish a data base against which
the vendor's claims for the technology could be evaluated reliably. Data from other
investigations by BioTrol are included to support the demonstration results. Conclu-
sions were reached concerning the technological effectiveness and economics of the
process and its suitability for use at other sites.
The primary conclusions from the demonstration study are:
(1) The Soil Washer effectively segregates the local soil into a coarse, relatively
uncontaminated fraction constituting the largest output portion, smaller fractions of
coarse and fine woody debris, and a contaminated fine fraction accounting for about
10% of the input solids weight.
(2) Starting with soils containing either 130 mg/kg or 680 mg/kg of penta, the
removal efficiency for penta in the Soil Washer, defined as the change in contaminant
concentration (weighted average) between the feed soil and the washed soil output
stream, ranged between 89% and 87%. Removal efficiencies for polynuclear aromatic
hydrocarbons were slightly lower, 83% and 88%, in tests with two soils. Concern
about the efficiency of the extraction step during analysis of the feed soil, leading to
low penta and PAH values, suggests that these values may be biased low. The vendor
claims a 90% removal efficiency.
(3) Based on the demonstration study, 27.5% to 33.5% of the pentachlorophenol
mass is concentrated in the fine particle cake fraction (as-is weight basis), between 18
and 28% is found in the coarse and fine oversize, and 34% to 39% is found in the
processing water. The washed soil retains only about 9%. Thus, while washing or
extraction of pentachlorophenol takes place, the predominant effect of the soil
processing was segregation of coarse and fine particles. Similar distribution occurs
with PAHs except that extraction into the aqueous fraction is much smaller due to the
much lower solubilities.
(4) While steady-state operation was not achieved in the anticipated acclimation
time (one week), the Slurry Bio-Reactor did achieve pentachlorophenol removals as
high as 93% and, based on extrapolation of the data, may well be capable of even higher
removal levels.
(5) The BATS successfully degraded between 91 and 94% of the pentachloro-
phenol in the aqueous process liquor, the Combined Dewatering Effluent: (CDE).
(6) Combined capital and operating costs for the integrated system are estimated
at $168/ton of feed soil, based on the MacGillis and Gibbs site. The Soil Washer
accounts for about 90% of the cost, followed by slurry biodegradation of the fine
particle slurry (about2%) and treatment of the aqueous stream (about 1 %). Unassigned
_
IV
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costs contribute about 5% to the total cost. Incineration of the woody debris found in
the soil is a major component of the Soil Washer costs, contributing about 80% of the
cost.
(7) On an individual unit basis, costs for the process were:
Soil Washer $185/metric ton or $154/short ton of soil or $197/yd3
(including incineration)
SBR $9.22/1000 Lor $34.39/1000 gal of 20% slurry
BATS $0.44/1000 Lor $1.65/1000 gal of water treated
Secondary conclusions that have been reached on the basis of the demonstration
study and other data provided by the vendor include:
(1) The Soil Washer also separates highly contaminated coarse oversize (wood
chips) and fine oversize (sawdust) fractions, typical of wood preserving facilities.
These fractions may be incinerated.
(2) The nature of the soil has a significant effect on the efficiency of soil washing
and/or the segregation into coarse and fine fractions that can be achieved. The soil
character (e.g., particle size) must be considered in evaluating the applicability of the
Soil Washing System.
(3) Depending on the nature and concentration of contaminants of concern,
acclimation of the Slurry Bio-Reactor may take considerably longer than the expected
one week. Laboratory scale experiments would be needed in each case to establish the
acclimation period. This may be important in scheduling and integrating units for a
particular site.
(4) The system is not without mechanical problems and complexities that still
need to be resolved. For example, clogging in the soil feed system forced a reduction
in Soil Washer operating rates, and foaming in the BATS, probably due to thickening
agent added for dewatering of the fines, created operational problems.
(5) The units evaluated in the demonstration study may not be appropriately-
sized for integrated operation. Similarly, for a full scale system, calculations have
indicated that a BATS capacity of about 300 gpm would be needed for the proposed
20 ton/hour soil processing rate. However, as discussed in the report, reuse of at least
a portion of the process water without treatment may be possible.
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Contents
Foreword x.u
Abstract ^
Figures VU1
Tables -. 1X
Abbreviations and Symbols x*
Conversion Factors XU1
Acknowledgments xlv
1. Executive Summary 1
2. Introduction 5
The Site Program 5
Site Program Reports 5
Purpose of the Applications Analysis Report 6
Key Contacts 6
3. Technology Applications Analysis 7
Introduction 7
Conclusions 7
Discussion of Conclusions 8
Operational Reliability/Stability 14
Costs 14
Applicable Wastes ; 1*
Site Characteristics "
Environmental Regulation Requirements 16
Materials Handling Requirements 17
Personnel Issues 17
Testing Issues 18
4. Economic Analysis 1"
Introduction 19
Conclusions 19
Issues and Assumptions , : 20
Basis for Economic Analysis 22
Results 26
5. Bibliography 2^
6. Appendices 31.
A. Process Description 31
Introduction 31
Process Description 31
Soil Washer 31
Slurry Bio-Reactor 31
BioTrol Aqueous Treatment System 32
Vll
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B. BioTrol Soil Washing System 35
Technology Description 35
Applicability 35
Performance 35
Laboratory Testing Services 35
On-site Demonstration Testing 37
Full Scale Soil Washing Systems 37
Advantages 37
Costs 38
C. Site Demonstration Results 39
Introduction 39
Soil Washer Performance 39
Input and Output Flow Rate Stability 39
Feed and Washed Soil Flow Rate Effects on Contaminant Removal 41
Fate of Contaminants 42
Slurry Bio-Reactor Performance 42
BioTrol Aqueous Treatment System Results 44
Test Procedures , 44
Sampling and Analysis , 44
System Parameters 44
Pentachlorophenol Removal 45
Mineralization of Penta 45
Polynuclear Aromatic Hydrocarbon (PAH) Removal 46
Heavy Metals 46
D. Case Studies 47
1. Treatability Studies of Soil Washer System 47
Wood Treatment Site (Penta/PAHs) 47
Wood Treatment Site (Penta/TRPs) 47
Pesticides Formulation Site 47
Industrial Chemical Site 47
Metal Contaminated Site 48
2. BATS Treatment at a Full Scale Wood Preserving Site 49
Introduction 49
Pilot Scale Studies 49
Commercial System Evaluation 49
Cost Data , 49
Conclusions 50
3. BATS Treatment at a Tape Manufacturer - California , 51
Introduction '. 51
Bench Scale Study ; 51
Results 51
Cost Data ...^51
4. BATS Treatment of BTEX-Minnesota 53
Introduction 53
Pilot Scale BATS 53
Full Scale BATS 53
Cost Data 53
5. Pilot Plant BATS-Minnesota ..".!.."."...."".. 55
Introduction 55
Pilot Scale Study ..."J..........55
Results 55
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Figures
1. Soil Washing System (SWS)
2. Penta and Particle-Size Distribution - Low Penta Soil Sample .
3. Penta and Particle-Size Distribution - High Penta Soil Sample.
4. Low Penta Soil Washer Test - Average Hourly Figures
5. High Penta Soil Washer Test - Average Hourly Figures
6. Penta Removal in the Slurry Bio-Reactor
7. Flowsheet - MacGillis and Gibbs Soil
A-l. Flow Diagram of the Soil Washing System (SWS)
A-2. Slurry Bio-Reactor Process Flow Diagram
A-3. Trailer Mounted BATS
A-4. BATS Process Flow
A-5. Polyvinyl Chloride Support Medium
B-l. Simplified BSWS Flow Sheet
B-2. Typical Plan View of Mobile 20 T/hr SWS .....
B-3. Estimated Treatment Cost ;
C-l. MacGillis and Gibbs Site
C-2. Solid Feed Rates - Low Penta Soil Washer Test
C-3. Liquid Flow Rates - Low Penta Soil Washer Test
C-4. Solid Stream Flow Rates - High Penta Soil Washer Test
C-5. Water Flows - High Penta Soil Washer Test
C-6. Penta Concentration - Low Penta SW Test
C-7. Penta Concentration - High Penta SW Test
C-8. Penta Removal in SBR
C-9. BATS Removal - Concentration in Low Penta Test
C-10. BATS - Concentration in High Penta Test
D-l. Phenolics Removal In Commercial BATS
D-2. PAH Removal in Commercial BATS
...9
.10
.10
.12
.12
.13
.20
.31
.32
.33
.33
.34
,.36
,.38
,.38
,.40
,.40
..40
..41
..41
..41
..42
..44
..45
..45
..50
..50
IX
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Tables
1. Particle-Size Distributions - Low & High Penta Contaminated Soil 8
2. Chemical Analysis of Fractions - Low Penta Concentration Soil .....:..9
3. Chemical Analysis of Fractions - High Penta Concentration Soil 10
4. Particle-Size and Chemical Analysis of Solid Process Streams/Low Penta SW Test 11
5. Particle-Size and Chemical Analysis of Solid Process Streams/High Penta SW Test 11
6. Average Mass/Hour Balance 12
7. Effectiveness of BATS System for Aqueous Stream (CDE) 13
8. Soil Washing System Mass Balance - Low Penta Soil 21
9. Soil Washing System Mass Balance - High Penta Soil 21
10. Estimated Product Flow Rates from Soil Washing '. 21
11. Estimated Costs for MacGillis and Gibbs Site 23
12. Soil Washing Capital Requirements Cost Analysis 23
13. Soil Washing Labor Requirements and Rates 25
B-l. Results of Laboratory-Scale Testing 36
C-l. Fate of Materials in the Soil Washer 43
C-2. Dioxin/Furan Distribution in the Soil Washer .; 43
C-3. Mass Removal of Pentachlorophenol 45
C-4. Comparison of Chloride and TOX Changes with Penta Removal 45
C-5. Weighted Concentrations of Metals in BATS Tests 46
D-l. Characteristics of Phenolic Process Water ..49
D-2. Wood Preserving Wastewater Treatment by BATS 49
D-3. Operating Cost for BATS Commercial Unit 49
D-4. BATS Removal Efficiency -Tape Process Water 51
D-5. Operating Cost for 10GPMBATS System 51
D-6. BTEX Treatment with the BATS 53
D-7. Groundwater Treatment in 30-Gal Packed Reactor 55
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Abbreviations and Symbols
BATS BioTrol Aqueous Treatment System
BOD biochemical oxygen demand (mg oxygen/liter)
BSWS BioTrol Soil Washer System
BTEX benzene, toluene, ethyl benzene, and xylenes
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act of 1980
cfm cubic feet per minute
COD chemical oxygen demand (mg oxygen/liter)
GC/MS gas chromatograph/mass spectrometer
gpd gallons per day
gpm gallons per minute
HPLC high pressure liquid chromatograph
HSWA Hazardous and Solid Waste Amendments to RCRA -1984
kwh kilowatt-hour
mg/kg milligrams per kilogram (ppm)
mg/L milligrams per liter (ppm)
NPL National Priorities List
O/G oil and grease
ORD Office of Research and Development (EPA)
OSWER Office of Solid Waste and Emergency Response (EPA)
PAHs polynuclear aromatic hydrocarbons
Penta pentachlorophenol (also PCP)
POTW publicly owned treatment works
ppb parts per billion
ppm parts per million
psi pounds per square inch
PVC polyvinyl chloride
QA/QC quality assurance/quality control
RCRA Resource Conservation and Recovery Act of 1976
RI/FS Remedial Investigation/Feasibility Study
RREL Risk Reduction Engineering Laboratory (EPA)
SAIC Science Applications International Corporation
SARA Superfund Amendments and Reauthorization Act of 1986
SBR Slurry Bio-Reactor
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SITE Superfund Innovative Technology Evaluation
TOC total organic carbon (rag carbon/liter)
TRPH total recoverable petroleum hydrocarbons
TSS total suspended solids (mg solids/liter)
Hg/kg micrograms per kilogram (ppb)
jig/L micrograms per liter (ppb)
xu
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Conversion Factors
Area:
Flow Rate:
Length:
Mass:
Volume:
English (US)
1ft2
lin2
1 gal/min
1 gal/min
1 Mgal/d
1 Mgal/d
1 Mgal/d
1ft
lin
lyd
lib
lib
1ft3
1ft3
Igal
Igal
Metric (SI)
9.29 x 10-2m2
6.45cm2
6.31 x lO5m3/s
6.31 x 10-2L/s
43.81 L/s
3.78 x KPmYd
4.38 x lO^Ys
0.30m
2.54 cm
0.91m
4.54 x KPg
0.45kg
28.32 L
2.83 x 10-2m3
3.79 L
3.79 x 10-?m3
ft = foot, ft2 = square foot, ft3 = cubic foot
in = inch, in2 = square inch
yd = yard
Ib = pound
gal = gallon
gal/min (or gpm) = gallons per minute
Mgal/d (or MOD) = million gallons per day
m = meter, m2 = square meter, m3 = cubic meter
cm = centimeter, cm2 = square centimeter
L = liter
g = gram
kg = kilogram
m3/s = cubic meters per second
L/s = liters/sec
m3/d = cubic meters per day
xm
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Acknowledgments
This project was directed and coordinated by Mary K. S tinson, EPA SITE Project
Manager in the Risk Reduction Engineering Laboratory - Cincinnati, Ohio.
Preparation of this report for EPA's Superfund Innovative Technology Evalua-
tion (SITE) Program was coordinated by Herbert S. Skovronek of Science Applica-
tions International Corporation for the U.S. Environmental Protection Agency under
Contract Nos. 68-03-3485 and 68-CO-0048. Contributors were William R. Ellis,
Omer Kitaplioglu, Jorge McPherson, Venkat Rao, Susan Roman, Sanjiv Shah and
others.
The cooperation and participation of Dennis D. Chilcote, Steven B. Valine,
Thomas J. Chresand and supporting staff of BioTrol, Inc. throughout the course of the
project and in review of this report are gratefully acknowledged, as is the assistance
of A J. Bumby of MacGillis and Gibbs.
Mark Lahtinen of the Minnesota Pollution Control Agency (MPCA) and Rhonda
McBride, Linda Kern, and Darryl Owens, the Remedial Project Managers of USEPA's
Region V, provided assistance and guidance in initiating the project and in
interpreting and responding to regulatory needs of the project.
Michael Borst, Douglas Grosse, and Gordon M. Evans of USEPA's Risk Reduc-
tion Engineering Laboratory provided technical reviews of the draft report.
XIV
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Section 1
Executive Summary
Introduction
One configuration of BioTrol, Inc.'s Soil Washing Sys-
tem (BSWS) has been used to treat pentachlorophenol-con-
taminated soil at a site on the Superfund National Priorities
List. Operational and cost data were collected for that inves-
tigation and serve as the primary basis for an evaluation of
the utility of this sequence of processes for remediation of
other sites across the Nation. Supporting data from other
studies and evaluation of one or more of the processes at
other sites are. discussed in Appendix D.
Conclusions
Based on the results of the SITE demonstration project
at the MacGillis and Gibbs site in New Brighton, MN and
information concerning other studies provided by the ven-
dor, BioTrol, Inc., for different wastes at other sites, several
conclusions can be drawn.
The Soil Washer is capable of segregating a penta-
contaminated feed soil (FS) into a major fraction of
washed soil (WS) retaining little (-10% by weight)
of the penta; smaller coarse and fine oversized (CO,
FO) fractions retaining contamination (-20-30%),
probably as woody debris; a fine particles (FPC)
fraction retaining the bulk of the contamination
(-30%) in a small mass; and a penta-contaminated
(-30%) aqueous stream called the Combined De-
watering Effluent (CDE).
Removal efficiencies for penta removal, defined as
the change in concentration from the feed soil to the
washed soil output stream (1-WS/FS), averaged
89% in the soil washer test for a soil with a low
penta concentration (130 mg/kg) and 87% in the
test with the high penta (680 mg/kg) soil. These
values are only slightly less than the vendor's claim
for a 90% removal efficiency. The removal effi-
ciencies for total polynuclear aromatic hydrocar-
bons (PAHs) were slightly lower, 83% and 88% in
the two tests.
Once acclimated, the Slurry Bio-Reactor (SBR)
should be capable of biologically degrading over
90% of the penta contamination in the fine particle
fraction. Concentrations of polynuclear aromatic
hydrocarbons are also extensively reduced (>70%).
Because of longer-than-anticipated acclimation at-
tributed to very high penta concentration in the
slurry, the system was not at steady-state for much
of the 14 day test. Consequently, the removal achiev-
able under steady-state operation could not be de-
termined.
The fixed-film biological treatment system (BATS)
is capable of destroying at least 91% of the penta-
chlorophenol in the process water from the soil
washer after acclimation with a penta-specific bac-
terium. Because of low influent concentrations and
high detection levels, removal of PAHs could not
be determined.
The removal of PAHs from the bulk of the soil and
concentration in the fines fraction appears to paral-
lel the behavior of the pentachlorophenol, except
that little is found in the process water, the Com-
bined Dewatering Effluent, probably due to lower
solubility.
Other constituents commonly encountered at such
sites, including oils and heavy metals, were re-
moved from the washed soil to varying degrees
(removal efficiency: oil: 80-90%; copper, chromium,
and arsenic: 50-70%).
Predicting operating costs for other sites is difficult
since one or more of the three processes may not be
needed (or the most attractive alternative) for a
particular site. Sizing of each process unit also must
be considered within a particular scenario and will
be dependent on time constraints for a cleanup,
volume/characteristics of soil, etc.
On the basis of an assumed 30,000 yd3 of soil to be
processed in a commercial system at the MacGillis
and Gibbs site using a 20 ton/hr Soil Washer coupled
with appropriately sized Slurry Bioreactpr (23 gpm)
and BATS (three 100 gpm) units, the cost (amor-
tized capital plus operating), based primarily on the
demonstration study, is estimated at $168/ton of
feed soil.
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The Soil Washer accounts for 90% of the total cost,
with incineration of the woody debris contributing
about 80% to the calculated Soil Washer cost. Slurry
biodegradation accounts for 2% of cost and aqueous
treatment accounts for 1% of the cost. Unassigned
costs contribute the remaining 5%.
Since all three unit operations may not be necessary
for a site, the following unit costs were also devel-
oped:
Soil Washer $154/ton or $197/yd3
Slurry BioReactor $34.39/1000 gal of 20% slurry
BATS $1.65/1000 gal of process water
Operating labor was a major operating cost factor
for all three units.
A major contributor to the cost for the Slurry Bio-
Reactor is the volume or mass of fines produced per
unit mass of feed soil, which translates directly into
the volume of slurry that will need to be treated.
The developer indicates that the Soil Washer Sys-
tem is effective with soils containing less than 25%
fines.
While contaminant concentrations and flow rate
attainable would be major contributors to the oper-
ating cost of the BATS, these factors are not major
considerations in the overall economics, assuming
that regulatory requirements for return of the washed
soil to the site can be satisfied.
One advantage of the Slurry Bio-Reactor and the
BATS processes over other biological treatment
processes is that they generate minimal quantities
of sludge that would require solids separation and
disposal.
Auxiliary equipment needed to support this process
is comparable to that for other aboveground treat-
ment systems, such as excavation and prescreening
of soil to remove oversized material and debris, oil/
water separators and clarifiers for pretreatment of
process water going to the BATS, and polishing
filters, carbon adsorbers, etc. that may be needed
for the effluent to meet local discharge require-
ments.
Discussion of Conclusions
The mobile pilot system tested at the MacGillis and
Gibbs site consisted of a Soil Washer (SW) with a nominal
capacity of 500 Ib/hr wet (as is), a Slurry Bio-Reactor (SBR)
with a throughput capacity of about 0.024 L/min (0.38 gal/
hr) as a 2-10% slurry, and a pilot scale BioTrol Aqueous
Treatment System (BATS) with a nominal hydraulic capac-
ity of about 10 gpm. All units can be transported to a site for
use in an evaluation.
Extensive data were collected over various segments of
a six week period to assess the ability of the system to
concentrate and then degrade pentachlorophenol and poly-
nuclear aromatic hydrocarbons from the soil at the site; to
establish the operational requirements of the system and its
individual components; and to arrive at the costs of opera-
tion in such a manner that future decisions could be made as
to the viability of one or all of the units for other sites. The
data from this study serve as the primary basis for the
foregoing conclusions. Additional supporting evidence was
provided from other studies by BioTrol.
An extensive Quality Assurance (QA) program was
conducted by SAIC under the supervision of EPA's QA
program, including audits and data review along with correc-
tive action procedures and special studies to resolve specific
data quality problems. These programs are the basis for the
quality of the data derived from the SITE project. Discussion
of the QA program and the results of audits, data reviews,
and special studies can be found in the Technology Evalua-
tion Report.
t
Two feed soils, containing different penta concentra-
tions, were prepared from the available soil for the study.
The "low penta" concentration soil was prepared by mixing
slightly contaminated soil from a former penta processing
area with a more highly contaminated soil previously exca-
vated at the site by BioTrol, The "high penta" soil was used
as excavated. The primary variables studied were:
A. In the Soil Washer:
a. input and output stream flow rates and totals
b. penta concentration of input and output streams
c. PAH concentrations of input and output streams
d. soil characteristics
B. In the Slurry Bio-Reactor:
a. overall penta concentration
b. penta distribution between solids and liquid
c. PAH distribution
C. In the BATS:
a. penta concentration
b. effect of metals, oil, etc.
The results of the SITE project demonstrated that the
soil washing process successfully segregated coarse soil
(major fraction) from fine clay and silt (small fraction).
While the bulk of the mass remains in the coarse soil, the
bulk of the penta and PAHs are in the fines fraction. In
addition, woody debris was removed as coarse and fine
oversize fractions, and an aqueous stream containing consid-
erable penta but little PAHs was generated. Of these, the key
product streams were the washed soil and the fine particle
cake (clay/silt), although the coarse oversize fraction also
retained a significant mass of penta, probably in woody
debris.
While one option may be off-site disposal of the highly
contaminated but small volume and weight of fine particle
material, a more attractive option may be treatment of that
material on-site in equipment such as the Slurry Bio-Reac-
tor. This unit was tested on a small portion of the fine
particle output stream. Over 90% of the pentachlorophenol
and over 70% of the PAHs were removed in the SBR when
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the system had been stabilized, leaving a fine particle slurry
with minimal contamination.
The system is a net consumer of water, absorbing about
10% of the 1200-1500 gallons introduced to transport and
process each ton of soil. Municipal water, treated effluent
from the BATS, and a dewatering polymer stream fed to the
thickener provide this water. Dewatering of the solid frac-
tions produces wastewater (Combined Dewatering Effluent,
CDE) contaminated with the pollutants of concern, in this
case penta and PAHs. The penta concentrations in the aque-
ous stream, up to its solubility limit of 80 ppm in the test
with the high penta soil, appear to validate BioTrol's claim
that the soil is washed or extracted as well as segregated by
particle sizes.
BioTrol's fixed-film aerobic reactor (BATS) success-
fully treated this wastewater (at 3 gpm), degrading over 90%
of the penta and producing an effluent suitable for recycle or
discharge at the MacGillis and Gibbs site. In retrospect,
there is some question whether there is a need to or benefit
from treating all of this water before recycle. Losses to the
various soil fractions, replaced by uncontaminated munici-
pal water, may avoid buildup of penta (and perhaps metals).
One option may be to treat a blowdown of the wastewater
before recycle to assure that penta and other contaminants do
not affect the quality of the washed soil product. Obviously,
considering the capital cost for the BATS at $250,000 for
300 gpm capacity, this could lead to considerable savings.
While the primary factor in the evaluation of the system
is the amount of penta on particular fractions of the soil, a
second critical factor is the concentration of key pollutants
that can be tolerated in the feed to the SBR and the BATS. At
least on a small scale, this study demonstrated that the Slurry
Bio-Reactor is capable of tolerating up to 5500 ppm of penta
(dry weight basis) on the incoming fines in the slurry. At
such a level, the solid surfaces may be inhibitory or toxic to
penta-degrading bacteria. Nevertheless, the fine solids may
serve as a reservoir of penta for the liquid phase until the
adsorbed film finally reaches a concentration amenable to
biodegradation on the surface. The dispersed bacterial popu-
lation would only see and degrade the soluble penta (under
100 ppm), which is much more tolerable based on BATS
results obtained by BioTrol in other studies.
Secondary pollutants such as oil and metals (including
copper, chromium, and arsenic from current CCA wood
treatment) did not appear to interfere with any of the three
processes, at least not at the concentrations present in the
soils (20-40 ppm each for arsenic, copper, and chromium in
the high penta soil test) and the duration of the tests during
the demonstration. If necessary, oil removal could be incor-
porated into the soil washing sequence or into the BATS.
The centrifuge used to separate the fine particle cake from
water can also separate oil if present. While there was some
indication that metals were building up as the wastewater
was recycled from BATS to soil washing, the short duration
of this investigation did not make it possible to establish if
an inhibitory effect might be observed in continuous opera-
tion. Clearly, such problems are surmountable, as by the
incorporation of metal precipitation, but overall treatment
cost would increase accordingly and additional hazardous
wastes would have to be managed.
Several of the polychlorinated dioxins and furans were
found in the soil and in some of the output streams at widely
varying but low concentrations. Of these, the octachloro
dioxin was the major isomer and the critical isomer, 2,3,7,8-
TCDD, was not detected. While concern over these pollut-
ants as byproducts from the manufacture of penta has, to
date, delayed disposal of the wastes from the demonstration,
their presence is not expected to affect large scale remediation
once safe disposal levels are established and approved dis-
posal routes are designated.
-------
-------
Section 2
Introduction
The SITE Program
The EPA's Office of Solid Waste and Emergency Re-
sponse (OSWER){and the Office of Research and Develop-
ment (ORD) established the Superfund Innovative
Technology Evaluation (SITE) Program in 1986 to promote
the development and use of innovative technologies to clean
up Superfund sites across the country. Now in its sixth year,
the SITE Program is helping to provide the treatment tech-
nologies necessary to meet new federal and state cleanup
standards aimed at permanent remedies, rather than short-
term corrections. The SITE Program includes two major
elements: the Demonstration Program and the Emerging
Technologies Program.
The major focus has been on the Demonstration Pro-
gram, which is designed to provide engineering and cost data
on selected technologies. EPA and the developers participat-
ing in the program share the cost of the demonstration.
Developers are responsible for demonstrating their innova-
tive systems at sites, usually Superfund sites agreed to by
EPA and the developer. EPA is responsible for sampling,
analyzing, and evaluating all test results. The outcome is an
assessment of the technology's performance, reliability, and
cost. This information, used in conjunction with other data,
enables EPA and state decision-makers to select the most
appropriate technologies for the cleanup of Superfund sites.
Developers of innovative technologies apply to the Dem-
onstration Program by responding to EPA's annual solicita-
tion. To qualify for the program, a new technology must
have a pilot or full scale unit and offer some advantage over
existing technologies. Mobile technologies are of particular
interest to EPA.
Once EPA accepts a proposal, EPA and the developer
work with the EPA Regional offices and state agencies to
identify a site containing wastes suitable for testing the
capabilities of the technology. EPA prepares a detailed sam-
pling and analysis plan designed to evaluate the technology
thoroughly and to ensure that the resulting data are reliable.
A demonstration may require a few days to several months,
depending on the type of process and the quantity of waste
needed to assess the technology. Thus, while it may be
possible to obtain meaningful results in a demonstration of
one week using an incineration process, where contaminants
are destroyed in seconds, this is not the case for a process
sequence such as that offered by BioTrol, where operational
reliability, integration of outputs from one unit to others, and
biological and system acclimation and stability must be
examined. In order to evaluate such parameters, it was
determined that a minimum of six weeks of operations was
necessary to evaluate the Soil Washer at two different penta
concentrations, provide the input streams for the Slurry Bio-
Reactor and BATS, and allow steady-state operation of the
biological reactors for about two weeks each. After com-
pleting a demonstration, EPA prepares two reports which are
explained in more detail below. Ultimately, the Demonstra-
tion Program leads to an analysis of the technology's overall
applicability to Superfund problems.
The second principal element of the SITE Program is
the Emerging Technologies Program, which fosters the fur-
ther investigation and development of treatment technolo-
gies that are still at the laboratory scale. Successful validation
of these technologies could lead to the development of
systems ready for field demonstration. A third component of
the SITE Program, the Measurement and Monitoring Tech-
nologies Program, provides assistance in the development
and demonstration of innovative technologies to better char-
acterize Superfund sites.
SITE Program Reports
The results of the SITE Demonstration Program are
incorporated in two documents, the Technology Evaluation
Report and the Applications Analysis Report. The former
provides a comprehensive description of the demonstration
and its results for engineers responsible for detailed evalua-
tion of the technology relative to other specific sites and
waste situations. These technical evaluators will want to
understand thoroughly the performance of the technology
during the demonstration, and the advantages, risks, and
costs of the technology for the given application.
The Applications Analysis Report is directed to officials
responsible for selecting and implementing remedial actions
for specific sites. This report provides sufficient information
for a preliminary determination of whether the technology
merits detailed consideration as an option in cleaning up a
specific site. If the candidate technology described in the
Applications Analysis appears to meet the needs of the site
engineers, more thorough assessment can be made based on
the Technology Evaluation Report and information from
remedial investigations for the specific site. In summary, the
Applications Analysis will assist in determining whether the
specific technology should be considered further as an op-
tion for a particular cleanup situation.
-------
Purpose of the Applications Analysis Report
Each SITE demonstration evaluates the performance of
a technology while treating the particular waste matrix found
at the demonstration site. Additional data from other projects
carried out by the developer also is presented where avail-
able.
Usually, the waste and/or soil at other sites requiring
remediation will differ in some way from the waste matrix
tested. Waste characteristic differences could affect waste
treatability and use of the demonstration technology at other
sites. Successful demonstration of a technology at one site
does not assure that the same technology or configuration
will work equally well at other locations. The operating
range over which the technology performs satisfactorily can
only be determined by examining a broad range of wastes
and sites. This report provides an indication of the applica-
bility of the BioTrol Soil Washer, the Slurry Bio-Reactor,
and the BioTrol Aqueous Treatment System, both as indi-
vidual operating units and as an integrated system, by
presenting and examining not only the demonstration test
data but also data available from other applications of the
technology by the developer.
To enable and encourage the general use of demon-
strated technologies, EPA considers the probable applicabil-
ity of each technology to sites and wastes in addition to those
tested, and strives to estimate the technology's likely costs in
these applications. The results of these analyses are made
available through the Applications Analysis Report.
Key Contacts
For more information on the demonstration of the Bio-
Trol Soil Washing System for contaminated soil or on the
companion evaluation of the BATS for contaminated ground-
water, please contact:
1. Vendor concerning the process:
BioTrol, Inc.
UPeaveyRoad
Chaska.Mn 55318
612-448-2515
Mr. Dennis D. Chilcote, Vice-President,
Engineering
Mr. Thomas J. Chresand, Development Engineer
2. EPA Project Manager concerning the SITE
Demonstration:
Ms. Mary K. Stinson
U.S. EPA - ORD
Technical Support Branch (MS-104)
2890 Woodbridge Avenue
Edison, NJ 08837-3679
908-321-6683
3. State contact concerning the MacGillis and Gibbs site:
Ms. Cathy O'Connell
Minnesota Pollution Control Agency
Site Response Section
Groundwater and Soil Waste Division
520 Lafayette Road
St. Paul, MN 55155
612-296-7775
4. EPA Regional contact concerning the MacGillis and
Gibbs site:
Mr. Darryl Owens
U.S. EPA, Region V
230 South Dearborn Street
Chicago, IL 60604
312-886-7089
-------
Section 3
Technology Applications Analysis
Introduction
This section addresses the potential applicability of the
BioTrol Soil Washing System (BSWS) to other soils and
Superfund site situations where pentachlorophenol and/or poly-
nuclear aromatic hydrocarbons are the pollutants of primary
interest. The demonstration at the MacGillis and Gibbs site
provides an extensive data base as a foundation for conclu-
sions on the effectiveness and the applicability to other clean-
ups. This data base is expanded somewhat by information
from treatability studies concerning other soils, other wastes,
and combinations of the two that have been provided by the
vendor.
The following subsections summarize observations and
conclusions drawn from the current study and supporting
information. Included are discussions of factors such as site
and soil characteristics, impact of state and federal environ-
mental regulations, unique handling requirements, resource
needs, and personnel factors. Additional information on the
BioTrol technology, including a process description, vendor
claims, a summary of the demonstration test results, and case
studies of treatability studies are provided in the Appendices.
Conclusions
Based on the results of the demonstration test program at
the MacGillis and Gibbs site, the vendor's claims for removal
efficiency are largely substantiated.
Removal efficiency, defined as [l-(Washed Soil cone/
Feed Soil cone)], averaged 89% and 87% for pentachlorophe-
nol (penta) in the tests with low penta- and high penta-
contaminated soils, respectively. Polynuclear aromatic
hydrocarbon removals were 83% and 88% in the two tests,
with removal values for some individual PAHs well above
90%.
The process can segregate a penta-contaminated soil that
is largely sand into a relatively uncontaminated coarse sand
fraction representing the bulk of the volume and weight of the
soil. The process is attractive where the washed soil meets
cleanup requirements and can be returned to the site without
further treatment. A smaller volume and weight of a highly
contaminated fines fraction (clay/silt) is also produced. Coarse
and fine oversize fractions containing penta-contaminated
woody debris also are separated. These materials could be
containerized and disposed of relatively inexpensively as a
hazardous waste, e.g., by incineration. Thus, the Soil Washer
acts as a waste volume reduction process.
Treating the contaminated fines fraction in a unit such as
the Slurry Bio-Reactor, using a bacterial strain acclimated to
the penta, may be more attractive than other destructive
means. Although based on only limited data, it appears that
the small-scale Slurry Bio-Reactor tested in this project can
achieve over 90% destruction of the penta and 70% or higher
removal of the associated PAHs, leaving a relatively
uncontaminated fine particle slurry (clay/silt). Disposal re-
quirements for all of these output streams from a particular
site will be dependent on both the material characteristics and
applicable state and federal regulations.
The water used to process (transport, agitate, abrade,
extract, and classify) the soil becomes contaminated with
penta, both by solubilization (washing/extraction) and by
entraining fine particles bearing penta. This water, called the
Combined Dewatering Effluent (CDE) and containing as much
as 80 ppm penta in the demonstration study, can be treated
successfully with BioTrol's Aqueous Treatment System
(BATS). Over 90% degradation of penta is achieved when the
CDE influent to the BATS contains 44 ppm penta. Based on
this study and the groundwater study of the BATS in the
companion SITE project, effluent concentrations of 1 ppm
and significantly lower are achievable. Conversion of penta to
inorganic chloride, water and carbon dioxide (mineralization)
rather than to intermediate organics appears to take place.
The concentration of PAHs from the feed soil into the
fines fraction probably reflects adsorption on the large surface
area of the fines. Biodegradation in the Slurry Bio-Reactor
achieved concentrations below detection limits for several of
the individual PAHs (10-100 ppb) even though the unit had
clearly not reached steady-state operation for much of the test.
Estimated removals between 70% and 99% were attained.
The costs for the system were examined on both an
integrated and on a unit process basis. This will help decision
makers decide if one, two, or all three of the processes are
needed and appropriate for a particular remediation. Extrapo-
lating the demonstration study to full scale treatment of the
MacGillis and Gibbs site, the integrated cost, including both
operating costs and capital costs amortized over an assumed
10 years, was $168/ton of feed soil. As individual units, the
costs were as follows:
-------
Soil washing/
segregation:
Slurry Bio-Reactor:
BioTrol Aqueous
Treatment System:
$154/ton soil treated (includes
incineration of woody debris)
$34.39/1000 gal of 20%
slurry
$1.65/1000 gal of process
water
How a system is designed, i.e., which processes are
employed, the sizes selected, how frequently they operate,
etc., obviously can affect total capital and contributing operat-
ing factors significantly. Section 4 of this report presents the
cost analysis in more depth along with the assumptions used
in arriving at the costs.
Discussion of Conclusions
The SITE program evaluation of one configuration of the
BioTrol Soil Washer System at the MacGillis and Gibbs
Company facility in New Brighton, MN demonstrated that the
contamination in the bulk of a soil can be greatly reduced.
The penta and PAHs are concentrated in a much smaller
volume of fines that can be further treated to biodegrade the
penta and PAHs. In the case of soluble contaminants such as
penta, contaminated process water is also produced and can be
treated biologically. Depending on the characteristics of the
soil (e.g., percent of fines, distribution of contaminants) and
the level of penta and PAH contamination, the washing pro-
cess will be more or less successful in segregating
uncontaminated sandy material (washed soil) and contami-
nated fines. Because of the nature of this SITE study, the
discussion is presented in terms of the process units evaluated,
i.e., Soil Washer, Slurry Bio-Reactor, and BioTrol Aqueous
Treatment System. Figure 1 provides a schematic of the entire
BSWS.
were subjected to particle size analysis by wet sieving. The
Unified Soil Classification System (USCS) was used to clas-
sify the soils into four characteristic soil fractions based on
size ranges, as follows:
Fraction
Size Range
Cobbles >76.2mm (3 inch)
Gravel 76.2mm to #4 sieve (4.75mm)
coarse gravel 78.2mm to 19.05mm
fine gravel 19.05mm to #4 sieve (4.75mm)
Sand #4 to # 200 sieve (4.75mm to .075mm)
coarse #4 to #10 sieve (4.75mm to 2.0mm)
' medium #10 to #40 sieve (2.0mm to .425mm)
fine #40 to #200 sieve (.425mm to ,075mm)
Fines (silts and clays) Below #200 sieve (<.075mm)
The low penta concentration soil sample was composed
of 5.74% gravel by weight, 71.2% sand, and 4.54% silt and
clay with 81.5% recovery of the original sample weight. The
high penta soil was composed of 2.53% gravel, 83.03% sand,
and 7.4% silt and clay with 93.0% recovery (Table 1).
Table 1. Particle-Size Distributions-Low & High F'enta
Contaminated Soil
Retained on Sieve
SoiTFraction Size Range
Low Penta
feed out
gm' %2 %2
High Penta
feed out
gm1 %2 %2
Grave!
Said-coarse
Sand-medium #10 to #40 sieve
Sand-fine #40 to #200 sieve
Fines
(Sift/Clay) betow #200 sieve
76.2mm to #4 sieve 61.8 5.74 7.0 11.7 2.53 2.7
#4to#10sieve 158.6 14.75 18.1 28.5 6.14 6.6
461.8 42.94 52.7 155.3 33.48 36.0
145.2 13.51 16.6 201.4 43.41 46.7
48.4
% Recovery
4.54
81.5
5.6
34.3 7.4
93.0
8.0
1 gm refers to the dry weights of the feed soil sample fractions
2 Feed results are based on material as recovered
Soil Washing
To help in properly evaluating the effect of the soil
washing, it is important to understand the size distribution of
the original soil and the distribution of penta in the soil
fractions. It should, however, be recognized that the particle
size analysis itself, using water, may have altered the distribu-
tion of penta by extracting additional penta. Consequently, the
particle size analysis may not be directly parallel to the soil
washing operation. Both particle size and contaminant distri-
bution can be significant factors in the utility of the BSWS.
Feed Soil Characterization
Two soil piles were prepared for the SITE study. The
"high penta" soil consisted of indigenous soil containing
about 600 ppm penta based on a composite analysis. The "low
penta" soil was prepared by mixing relatively uncontaminated
soil from a former penta processing area with another highly
contaminated soil excavated at the site earlier by BioTrol. The
mixed soil had an average penta concentration of 133 ppm.
Samples of both the low and high penta concentration
soils used to demonstrate the BioTrol Soil Washing System
After wet sieving, solid fractions were analyzed for pen-
tachlorophenol (penta), polynuclear .aromatic hydrocarbons
(PAHs), and copper, chromium, and arsenic (CCA). The
fractions were grouped as follows for analyses:
Material retained on the #4 and #10 sieves
Material retained on the #20 and #40 sieves
Material retained on the #60, #140, and #200 sieves
Solid material passing the #200 sieve
Aqueous solution passing the #200 sieve.
Table 2 summarizes the chemical analyses for the low
penta concentration soil sample. While the analyses do not
quite parallel the USCS classification of the soil shown in
Table 1, the highest concentrations of contamination are found
in the traction with the smallest grain sizes (<200 mesh),
equivalent to the fine particle cake from the Soil Washer, and
the fraction with the largest grain sizes (>10 mesh), which
would be equivalent to the coarse and fine oversize fractions.
The medium and fine fractions most closely match up with the
washed soil from the Soil Washer. Similar results were
obtained for the high penta concentration soil (Table 3).
Figures 2 and 3 graphically show the distribution of penta
mass and the percent of soil represented by each size range in
8
-------
[ Oversize |
1 Debris J
"" ^\ 1 - * I
Contaminated ^_ ,, ซ ___ Mixing
Soil oueen Trommel -1
Water
Holding
Tank
1,
Aqueous
Treatment
System
[Coarse j
I Oversize)
j
1 Municipal |
Water
^ Supply J
4
* Froth
*" Screen " s"" Hotation
V
C Fr
l
nth V .....
Combined -ซฃ, Thir.Uoninn -
Dewatering j
Effluent
Holding Tank
\
E ,
>,
Sluage t
Jnderflowor L--
Fine Particle
Slurry J
\
t
f~ Fine ^N
\OversizeJ
Multi-Stage
Attrition/Classification
Circuit
...J ,
Clays, and
1 1 OrganicsJ
Slurry
Bio-Reactor
i
r .- ^\
t ;- Fine Particle 1
^ Cake J
(Washed
>-5ป~ Soil
. Product
x-
(Cationic
Polymer
Figure 1. Flow Diagram of the Soil Washing System (SWS) with Sample Points.
the two soils. In both cases, the gravel and coarse sand
contribute the largest mass of penta while accounting for 25%
or less of the soil weight. While a significant portion of the
penta may have dissolved into the aqueous solution, as found
later in the demonstration study, the solutions were not ana-
lyzed due to laboratory problems.
It should be noted that the coarse fraction retained glob-
ules of tar or "tar balls", which did not break up readily and
which may contribute to the high penta concentration.
Solid Process Stream Characterizations
Samples of the solid process streams from both the low
penta soil washer test and the high penta test also were
subjected to particle-size and chemical analysis. These pro-
cess streams (see Figure 1) were as follows:
Washed Soil (WS)
Fine Particle Cake (FPC)
Fine Oversize (FO)
Coarse Oversize (CO).
On the USCS basis, the washed soil (WS) would be
classified as a medium-grained sand with 89% and 96% of the
particles for the low and high tests, respectively, falling in the
sand range. The fine particle cake would be classified as fines
(silts and clays) with 75% and 62% of the particles in the fines
range.
Table 2. Chemical Analysis of Fractions - Low Penta
Concentration Soil
Fraction
feed gravel/ medium fine silt/ aqueous
soil* coarse sand sand clay
sand
% of sample **
% of orig. sample 100
pentachbrophenol 133
PAHs
fluorene 11.5
phenanthrene 25.3
anthracene 118.5
fluoranthene 16.4
pyrene 28.0
benzo(a)anthracene 4.1J
chrysene 9.9
benzo(b)fluoranth3ne 3.1J
arsenic 13.1
chromium 15.5
copper 13.0
25.16
20.49
240
ND '
15
140
16
29
ND
12
ND
13.3
14
13.2
52.72
42.94
42
3.4J
7.1
45
4.8
6.4
1.2J
2.8J
1.0J
2.9
5.5
4.2
16.58
3.51
la'^a
48
1.1J
3.1
13
2.2
^8
ND
1.3J
ND
2.4
5.4
3.7
5.53
4.54
240
14
31
230
21
40
ND
16
ND
17.5
46
22.7
nj ^
3.05
MA
MA
NA
NA
NA
NA
NA
NA
NA
3.6
3.2
2.9
NA = not analyzed; ND = not detected
J = estimated, 0. if necessary.
* = organic analyses are averages of eight samples, metals are
from composite sample.
** % = 100 x (sample wt. on screen/total sample wt. recovered).
-------
Tablo 3. Chemical Analysis of Fractions - High Penta
Concentration Soil
Fraction
%of sample**
% of orig. sample
ponta
PAHs
acanaphthone
(luorono
phonanthrone
anthracene
fluoranthene
pyrene
benzo(a)anthracene
chrysene
benzo(b}fluoranthene
bonzo(k)fluoranthene
benzo(a)pyrene
arsenic
chromium
copper
feed
soil*
100
100
512
19.6
20.8
76.2
35.5
69.5
69.6
17.0
26.9
11.5
9.9
5.3
21.9
32.1
28.5
gravel/
coarse
sand
9.32
8.67
1200
27
25
97
66
89
99
24
40
10
ND
ND
41.1
64.5
55
medium
sand
36.02
33.48
250
6.6
4.6
18
19
29
26
6.3
14
4.9
4.5
2.4J
5.9
20.8
10.4
fine
sand
46.70
43.41
160
4.7
4.4
17
8.5
21
19
4.2 J
7.4 J
ND
ND
ND
7.2
7.6
6.7
silt/ aqueous
day
7.96
7.40
1100
22
19
130
32
200
160
18
30
13
10
8.4
67
97.4
78.6
____T_
4.23
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA .
NA
0.38
0.28
0.34
NA = not analyzed; ND = not detected
J - Estimated, 0
* - Organic analyses are averages of 12 samples, metals are from
composite sample
" % = 100 x (sample wt. on screen/total sample wt. recovered)
The fine oversize fractions would be classified as me-
dium-grained sand with 85% and 77% of the particles falling
in the sand range. It had the appearance of peat moss and
consisted largely of very small organic fibers. Based on this
laboratory description and using the USCS, the fine oversize
could be classified as a highly organic soil. The coarse over-
size would be classified as a coarse-grained sand, with the
predominant particle-size falling in the sand range (72% and
82% respectively). It also contained gravel (30% in the low
penta soil and 21% in the high penta soil).
60
55
50
45
40
35
30
25
20
15
10
5
0
Pentachlorophenol (mg)
% of Soil by Weight
Mass of PGP V7771 % of Soil By Weight
aravel +
Coarse Sand
Fines
(Silts/Clays)
100%
90%
1 80%
1 70%
60%
50%
40%
30%
20%
10%
0%
Soil Fractions
Rgure 2. Particle-Size Fraction Analysis
Low Penta Concentration Soil Sample.
(1075 gm sample)
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Pentachlorophenol (mg)
% of Soil by Weight
I Mass of PGP E223% of Soil By Weight
100%
Gravel +
Coarse Sand
Fines
(Silts/Clays)
- 90%
80%
- 70%
- 60%
- 50%
- 40%
- 30%
- 20%
410%
o%
Soil Fractions
Figure 3. Particle-Size Fraction Analysis
High Penta Concentration Soli Sample.
(464 gm sample)
The highest concentrations of penta and PAHs occur in
the coarse oversize (gravel, wood particles, and coarse sand)
and fine particle cake (silts and clays) streams. Distribution of
PAHs and chromium, copper, and arsenic follow a similar
pattern, in general, with higher concentrations on fine particle
cake and coarse and fine oversize fractions. Particle size and
contaminant distribution are summarized in Tables 4 and 5.
Particle-size analysis of the individual process streams
confirms that the BioTrol Soil Washing System succeeded in
separating the soil into specific particle-size fractions.
The following observations can be made by comparing
the results from the particle-size analysis and chemical analy-
sis of particle-size fractions of the feed soils and the solid
process streams:
The highest concentrations of contamination occur
in the oversize (>10 mesh) and fines (<200 mesh)
particles.
The oversize (>10 mesh) and fines (<200 mesh)
contribute more than 50 % of the penta mass while
making up only 20-30 % of the soil weight.
r
Mass Distribution - Soil Washer
Overall, the soil washing process results can be summa-
rized for the low and high penta contaminated soils as shown
in Figures 4 and 5. The major portion of the penta is found on
the fine particle cake (33.5% and 27.5%, respectively in low
penta and high penta soil washer tests). The total (carcino-
genic and non-carcinogenic) PAHs follow a similar pattern
with 61% and 55%, respectively, on the fine particle cake.
Much less of the relatively insoluble PAHs are extracted into
the aqueous phase. In spite of the careful use of proper
procedures in making all measurements, the output rates of
solids, penta, and PAHs are higher than the input rates, as
summarized in Table 6. While there are no explanations for
10
-------
Table 4. Particle-Size Analysis and Chemical Analysis of Solid Process Streams Low Concentration Soil Test
Washed Soil Fine Particle Cake Fine Oversize Coarse Oversize
% Soil on Sieve % Soil on Sieve% Soil on Sieve
Process Stream:
Particle-Size Results
sieve ff/rracuun OI^B
#3/8 /9.50mm
#4 / 4.75 mm
#10 /2.00mm
#20 / .850 mm
#40 / .425 mm
#60 / .250 mm
#140 /.106mm
#2007 .075 mm
Pan < .075 mm
Total % Recovery
Analytical Results*
Pentachlorophenol
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Benzo(a)anthracene
Chrysene
Benzo(b)fluoranthene
Copper
Chromium
Arsenic
+
3%
76%
7%
6%
1%
2%
95%
19
ND
0.870 J
5.2
1.5 J
2.9
0.33 J
1.2J
ND
5
6.4
3.9
+
+
+
8%
5%
3%
3%
75%
94%
210
43
120
490
42
83
12
34
6.5 J
44.9
47.6
41.9
+
+
76%
3%
2%
3%
1%
6%
91%
130
33
74
260
18
15
3.7 J
9.8 J
2.4 J
8.8
9.7
7.5
9%
21%
30%
38%
1%
1%
1%
1%
3%
105%
190 E
15
38
68E
14
21
3.3
8.8
1.7J
15
22.4
5.6
+ - Sieve not used in particle-size analysis of this sample.
* - All analytical results are reported in mg/kg.
E - Exceeds the calibration.
J - Estimated value; less than the sample quantitation limit but greater than zero.
ND - Analyzed, not detected.
Table 5. Particle-Size Analysis and Chemical Analysis of Solid Process Stream* - High Concentration Soil Test
Process Stream:
Particle-Size Results
Sieve #/Fraction Size
#3/8 / 9.50 mm
#4 / 4;75 mm
#10 /2.00mm
#20 / .850 mm
#40 /.425mm
#60 / .250 mm
#140/.106mm
#200 /.075mm
Pan < .075 mm
Total % Recovery
Analytical Results*
Pentachlorophenol ,
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Benzo(a)anthracene
Chrysene
Benzo(b)fluoranthene
Copper
Chromium
Arsenic
Washed Soil
% Soil on Sieve
+
+
+
4%
63%
19%
9%
i%
2% '
98%
110
4.3
16
6.7
17
11
3.1 J
5.6
1.9
20.6
33
11.8
Fine Particle Cake
% Soil on Sieve
+
+
+
+
'4%
12%
11%
1 1%
62%
100%
1500
56
240
130
180
200
59 J
65J
31
120
113
80.8
Fine Oversize
% Soil on Sieve%
+
+
+
73%
1%
1%
1%
1%
24%
101%
430
14
47
42 B
39
35
9.1
17
6
17.3
24.8
16.8
Coarse Oversize
Soil on Sieve
5%
16%
28%
48%
2%
2%
3%
1%
3%
106%
1000
oo
ฃc.
81
33J
74
60
14
26
7.8 J
36.7
80.8
36.6
+ - Sieve not used in particle-size analysis of this sample.
* - All analytical results are reported in mg/kg.
B - Found in the associated method blank.
J - Estimated value; less than the sample quantitation limit but greater than zero.
11
-------
As is Soil
(Dry Solids
Penta
Total PAH's
220kg
195.8kg)
28.6 gm
54.3 gm
Soil Wash, Classify, Dewater
"
Asiswt.
Diywt.
Penta wt.
% Total Penta
PAH's
% of PAH's
Figure 4. Low Penta Soil Washer Test - Weighted Hourly Rates.
1
1
Coarse
Oversize
32kg
22.1 kg
5.44 gm
14.0%
9.88 gm
16.1%
Fine
Oversize
13kg
1.04kg
1.25gm
3.2%
2.71 gm
4.4%
Fine
Particle
48kg
14.4kg
1 2.96 gm
33.5%
37.33 gm
60.8%
Washed
Soil
260kg
189.8kg
3.64 gm
9.4%
10.93gm
17.8%
Combined
Dewatering
Effluent
1100kg
0
15:4gm
39.8%
0.55 gm
0.9%
Asiswt
Dry wt.
Penta wt.
% Total Penta
PAH's
% of Total PAH's
Figure 5. High Penta Soil Washer Test - Weighted Hourly Rates.
As is Soil
(Dry So I)
Penta
Total PAH's
Coarse
Oversize
28kg
13.2 kg
39.2 gm
23.0%
14.75gm
22.0%
160kg
134.4kg
108.8gm
64.6 gm
Fine
Oversize
9.1kg
1.4kg
8.2 gm
4.8%
4.13 gm
6.2%
Water 816 kg
Penta 1 .85 gm
PAH's 0 gm
I
i
Fine
Particle
36kg
12.6kg
46.8 gm
27.5%
36.88 gm
55.0%
Washed
Soil
210kg
144.9 kg
18.3gm
10.8%
9.89 gm
14.8%
Combined
Dewatering
Effluent
720 kg
0
57.6 gm
33.9%
1 .38 gm
2.0%
Table 6. Average Mass/Hour Balance
Low Penta Soil Washer Test:
material
input/hr
dry son solids
water
ponta
PAHs
195.8kg
1404.2 kg
28.6 gm
54.3 gm
High Penta Soil Washer Test:
dry soil solids
water
ponta
PAHs
134.4 kg
841.6kg
110.6gm
64.6 gm
output/hr
227.3 kg
1225.7kg
38.7 gm
61.4gm
173.2kg
829.9 kg
170.1 gm
67.0 gm
mass
balance
-t-16%
-13%
+35%
+13%
+29%
-1%
+54%
+ 4%
the poor soil mass balance, it has been postulated that the
higher total penta and PAH concentrations and masses mea-
sured in the output streams may be the result of improved
accessibility for the analytical extractions from the break-
down of agglomerated soil during the soil washing.
Only low concentrations of any of the dioxins and furans
were detected in any of the feed or output streams from the
soil washing. The key isomer of concern, 2,3,7,8-TCDD, was
not detected. The distribution of dioxins and furans to the
output streams also followed the general pattern observed
with penta, with the highest concentration of combined spe-
cies, as "Total CDD/CDFs", in the fine particle cake and the
lowest in the washed soil in both the low penta and the high
penta soil washer tests. On this basis, the removal efficiencies
(1-WS/FS) were 92% and 97%, respectively.
12
-------
On a mass basis, the fine particle cake accounted for 63%
(low penta) and 71% (high penta) of the Total CDD/CDFs.
The washed soil from the two tests accounted for only 12%
(low penta) and 5% (high penta) of the Total CDD/CDFs
mass.
Slurry Bio-Reactor Effectiveness
The fine particles from the soil washing can simply be
dewatered, containerized, and disposed of as a hazardous
waste, probably by incineration. By eliminating the bulk of
the soil, the mass of contaminated material is drastically
reduced to about 20% of the feed soil weight on an as-is basis
and such disposal may, in certain circumstances, be the most
cost-effective route. However, to demonstrate a more envi-
ronmentally attractive alternative, the output of 1 day of the
fine particle slurry production was collected during the high
penta soil washer test and then treated in the Slurry Bio-
Reactor over about fourteen days after first acclimating the
system for five days. With an average retention time in the
system of about 5.2 days, the system did not reach steady-
state until about the fifth day of evaluation. Only after 9 days
of operation did: degradation of penta begin to level off, at
almost 95% removal (Figure 6). Other operating difficulties
(e.g., insufficient nutrient for high penta concentrations, fro-
zen lines) also made the results of the earlier days non-
representative. It should also be noted that the size of the
equipment used and the resulting throughput rate, 24 ml/min,
are significantly smaller than for the Soil Washer or the
BATS.
On the basis of these results it appears that in a commer-
cial operation, where the acclimation period would be less
important, consistent removals of at least 90% of penta can be
achieved from the fines. Removal of the PAHs also appeared
to parallel that of penta, with removals of between 70% and
over 90% being achieved for various species in the later days
of the test.
o
c
o
O
100
90
80
o_
o
Q.
a 70
ฃ
60
50
40
30
20
10
0
g
(8
m
o
I
_L
_L
The fines in the slurry from this high penta test that are
fed to the Slurry Bio-Reactor contain about 5500 ppm of
penta on a dry weight basis. At this level, biodegradation may
be inhibited on the surface of the solid. Instead, the solids may
be serving as a reservoir or ballast for penta. As penta is
consumed in the aqueous phase, more is dissolved from the
solid. Only when the concentration on the solids has de-
creased to some non-toxic level is it likely that biodegradation
on the surface of the fines begins to play a role. This may be a
contributing factor for the delay in attaining steady-state
conditions in the reactor.
BioTrol Aqueous Treatment System
The process water generated by the attrition/classification
sequence is separated from the soil fractions. Since a signifi-
cant volume of water is retained by the solids, it is beneficial
to recycle as much of the water as possible.
BioTrol's Aqueous Treatment System is well suited to
treatment of this wastewater. Having been studied in depth in
the companion study, investigation of the BATS in this project
was limited to a demonstration of its effectiveness for the
wastewaters generated from the low penta and the high penta
soil washing to assure that no new or unexpected effects were
encountered when using an influent other than groundwater.
The mobile (nominal 10-gpm) system was used for this pur-
pose. Once the system was acclimated and inoculated with
penta-specific bacterium, it operated effectively on the two
wastewaters, achieving over 90% penta removal and produc-
ing a reusable effluent (Table 7).
Makeup water requirement of the soil washing process is
such (=4200 gal/ton soil) that a very large BATS would be
required to treat all of the output water. For a 20 ton/hour
commercial soil washer, BATS units with 300 gpm capacity
would be needed. However, in light of the much higher
concentration and mass of penta in certain output soil streams,
treating all of the recycle water may not be necessary. This
would be a much more attractive option from both an opera-
tional and a cost point of view.
Table 7. Effectiveness of BATS System for Aqueous Stream
(CDE)
Influent Penta* Effluent Penta* Removal
mg/L mg/L %
34567
Influent Flow Test Day
low penta test
high penta test
15
44
1.4
3.0
90.6
93.2
Figure 6. Overall Penta Removal Efficiency in SBR.
* All concentrations are weighted averages derived from the total
mass of penta divided by the total flow during a sampling period
PAH concentrations were below detection limits (2-15
jig/L in the low penta test and 1-400 jxg/L in the high penta
test) in the influent to the BATS; consequently, no determi-
nation can be made as to the ability of the BATS to remove
these materials. However, the influent to the BATS from the
low penta and high penta soil washer tests (after storage) did
contain PAHs, at total concentrations of about 0.41 mg/L
and 1.5 mg/L, respectively. In a pilot scale study of the
BATS at another wood preserving site, >80% removal of
PAHs was demonstrated. Those results also indicated that
13
-------
both biodegradation and absorption on biomass contributed
to PAH removal from the aqueous waste stream.
Mineralization of Pentachlorophenol
Limited analyses of influent and effluent for chloride
and total organic chlorine were carried out in an effort to
confirm that the removal of penta occurred by total degrada-
tion to water, carbon dioxide, and chloride ions rather than to
partially chlorinated products not detected by the analytical
protocol. While the changes in these parameters were consis-
tent with total degradation (mineralization) of the penta,
insufficient data were gathered to allow a conclusion con-
cerning mineralization. The companion study using the BATS
on groundwater as well as published studies with carbon
isotopes provide a more defensible basis for concluding that
mineralization is the primary mechanism.
Operational Reliability/Stability
SoilWasher (SW)
The only major operating problem encountered during
the SW tests occurred during the transfer of soil from the
feed hopper to the conveyor belt. The feed hopper was a new
feed system being used for the first time during this demon-
stration. Coating of the screws in the feed hopper with soil
required an increase in the auger rate from 10% to 80% to
maintain the same feed rate. This higher auger rate is subject
to greater variability in output. The problem was attributed
to a higher-than-expected moisture content of the soil. Aera-
tion of the feed soils to decrease their moisture content and
modification of the feed hopper with a vibrating device and
inclined wooden walls helped keep the augers clear and
enabled the demonstration tests to be completed, although at
a lower input rate. In a commercial scale system, a different
means of delivering soil to the conveyor belt will be needed.
Minor problems that were encountered included blown
fuses, a broken shim on an attrition machine, and failures of
the centrifuge and various pumps. In a commercial opera-
tion, back-up equipment or parts would need to be readily
available to avoid shut-down of the system, or two soil
washers might need to be run in a parallel configuration to
allow for the shut-down of one unit for routine maintenance.
BioTrol Aqueous Treatment System (BATS)
Operational problems encountered during the demon-
stration included a leaking influent pump, a leaking recycle
line, worn bearings in the influent pump, and overheating of
the BATS reactor. Repairs of the pumps and recycle line
were relatively minor but did require the cut-off of feed to
the system for short periods of time. Having replacement
pumps on hand would avoid any loss of feed for more than a
few minutes. The overheating of the BATS reactor occurred
due to a major decrease in flow rate (from 3 gpm down to 0.5
gpm) when the bearings in the influent pump wore out. This
decrease in flow rate should have been accompanied by a
corresponding decrease in the thermostat setting on the
heater; overheating occurred when the thermostat was not
manually readjusted. The result was thermal deactivation of
the biomass due to extreme temperatures in the BATS reac-
tor. Since this occurred on the 10th day of the demonstration
and considerable data had already been collected, the dem-
onstration was terminated.
The system proved to be quite stable and required a
minimum of attention during the study. Other than emer-
gency repairs noted above, routine checking of pH, and
preparation of nutrient solutions, there was little need for an
operator. With a large reservoir of relatively constant feed
water such as that provided, by the soil washer system, the
operator attention required would be minimal. In a larger
system, some means of on-line monitoring to alert an opera-
tor to out-of-compliance conditions or other failures may be
desirable when the operator is occupied elsewhere.
Slurry Bio-Reactor (SBR)
Operating problems encountered during the demonstra-
tion of the SBR included clogging of the lines connecting the
cells of the reactor, rupture of the line in the effluent pump,
overloaded circuit breakers, and frozen lines due to ambient
temperatures below freezing. A rubber mallet was used to
loosen material caught between reactor cells; in a larger
system this is not expected to be a problem. The line in the
effluent pump was replaced following each occurrence of a
rupture. The overloaded circuit breaker was reset as soon as
it was discovered, which was immediately upon occurrence.
Because the capacity of the SBR was significantly lower
than the output from the soil washer, the fine particle slurry
was collected in a reservoir tank for about one day during the
middle of the high penta soil washer test. The slurry in the
tank was circulated to minimize settling and a portion was
diverted as feed to the SBR for 6 sec/min, using a timer and
solenoid valve, throughout the 14 day test of the SBR. If
power were lost for any extended period of time, this timer
would need to be reprogrammed. Although the reactor cells
are equipped with automatic temperature controls, the feed
tank was not. A propane heater was used inside the tempo-
rary structure on extremely cold nights to keep the feed from
freezing.
Costs
Cost data were developed for the system as demon-
strated at the MacGillis and Gibbs site and by applying other
information provided by BioTrol. Scaling up the entire sys-
tem can require or allow some changes in equipment selec-
tion (and cost) for soil handling; the effect on operating costs
such as labor and electrical uiie are not, however, expected to
be significant. The equipment used in the commercial-scale
Soil Washer is commonly used by the mineral processing
industry.
Based on this demonstration test, the Slurry Bio-Reactor
is simply not well enough developed at this point to be able
to anticipate any changes in operating costs that might occur
on scale-up. As with scale-up of the BATS, other than some
savings achievable by buying nutrients and acid/base in
bulk, the major factor in operating cost is the labor to
14
-------
oversee the operation; larger systems will require less atten-
tion on a volume ithroughput basis.
In the case of the BATS, the developer has indicated
that the proposed three parallel trains of bioreactor cells
would provide some cost saving since fewer pumps and
monitoring instruments would be required.
Applicable Wastes
It should be emphasized that treatability tests should be
done to determine the feasibility of the soil washing process
for specific soils and contaminants at a particular site.
BioTrol has demonstrated its soil washing technology
in such treatability tests at the laboratory scale on soils with
a variety of contaminants. Organic contaminants on the
washed soil, the primary soil output stream, are reduced by
87-89% and heavy metals by 46-72% in this demonstration
and somewhat higher based on other data provided by the
vendor. Where the contaminants are associated principally
with the fine particle fraction, the amount of silt and clay,
i.e., the weight of soil passing a 200 mesh screen (<0.075
mm), should not normally exceed 25-35 percent of the feed
soil in order to achieve an economical volume reduction
(see Reference 4). Fluctuations in the particle size distribu-
tion of the feed soil also may upset soil washing. These
constraints have been verified (References 19 and 31) by
vendors whose primary experiences have been in Europe.
Furthermore, high organic matter and high moisture content
may interfere with the use of soil washing as a cost-effec-
tive remediation option.
While this study of the BioTrol Soil Washer System
was limited to two contaminated soils derived from a single
site and data on other soils is limited, the results of the study
along with other information provided by the vendor sug-
gest that the technology would have wide applicability to
other contaminated sites. Interest in soil washing is clearly
reflected in the design and marketing efforts of other ven-
dors.
The BioTrol system should be readily applicable to
other Superfund sites where wood preservation was carried
out with penta or creosote. In each case, the soil would need
to be characterized to assure that it met the coarse/fine
(under -30% fines) needs of the BioTrol system and that
moisture content (from rainfall, water table, etc.) would not
hinder processing. And, while this study does not provide
any insight into the fundamental chemistry of the soil at the
MacGillis and Gibbs site, such studies may be necessary to
predict the adsorption/desorption equilibrium for other con-
taminant/soil matrices. This could affect the role washing/
extraction plays as well as the distribution of contaminants
between fine and coarse material.
The very different nature of the key chemical species,
pentachlorophenol and polynuclear aromatic hydrocarbons,
suggests that at many Superfund sites where hydrophobic
organic chemicals are of concern soil washing could be
useful for volume reduction by particle size segregation.
This might, for example, include contaminants such as
dioxins and polychlorinated biphenyls (PCBs) where con-
centration into a particular fraction for a specific destruction
process might be economically attractive. At this time it is
not possible to state whether the Slurry Bio-Reactor would
be an effective means of degrading concentrates of such
pollutants.
Further, if a washing/extraction phenomenon does occur
with a particular soil and contaminants, it suggests an avenue
for removal and concentration of a variety of organic and
inorganic contaminants, either with water alone or, perhaps,
with aqueous solutions of various reagents (e.g., acid/base,
surfactants, etc.). More hydrophilic organics (e.g., acetone,
methyl ethyl ketone, phenol, etc.) would be expected to
partition more into the aqueous phase, while oils, hydrocar-
bons, and halogenated hydrocarbons would be retained by
fine soil particles and be partitioned to a lesser extent into
the aqueous phase. Simple additives (acids, bases, wetting
agents, etc.) may increase solubility or solubilization rate.
For example, the addition of acid to the processing water
may improve metal extraction from soil; caustic would be
expected to increase the extraction of phenols (including
pentachlorophenol) by conversion to the more water-soluble
phenate ions. Of course, such contaminated extracts may
require additional treatment and impose additional cost for
their disposal.
The experience at MacGillis and Gibbs with the Slurry
Bio-Reactor and the BATS did not indicate nor suggest a
particular sensitivity to temperature, dissolved oxygen, met-
als, or oil beyond that which is inherent in aerobic biological
treatment. Thus, with minor pretreatment, a variety of con-
taminated slurries and aqueous waste streams from soil
washing may be adaptable to treatment in these units - with
or without pollutant-specific inocula.
Site Characteristics
The first consideration at any site would be the type and
amount of debris that can be expected during excavation.
Bulky materials must be removed before the soil washing
process is implemented. The time and cost of such opera-
tions can play a role in the overall cost-effectiveness of any
soil remediation project.
While this project did not specifically investigate the
effect of soil character and particle size distribution on the
nature of the output, such factors can affect the efficiency of
washing and the volumes and masses of different output
fractions; pollutant distribution may behave in the same or a
different manner. Any soil being considered for the BSWS
would benefit from a particle size distribution and pollutant
distribution analysis, even though the results probably can
only be used in a general sense in predicting performance
during soil washing. As noted earlier, too high a fines
content may interfere with operation of the soil washer
equipment (clogging) and produce a relatively small yield of
coarse sand and large amounts of fines requiring off-site
disposal or treatment in equipment such as the Slurry Bio-
Reactor. And, only if washing and segregation partition the
contaminants of interest into the water and/or onto one
15
-------
predominant solids stream (e.g., the fines), would the pro-
cess provide the desired benefits.
In the demonstration program, mobile pilot plant units
were used. These required only a level base (a concrete pad),
power, and water. The process is a significant consumer of
water, the amount depending on the moisture content of the
soil and the ability and need to dewater coarse and fine
output streams before returning them to the site or transport-
ing them for off-site disposal. Reuse of aqueous streams
from dewatering of solid streams, from the Slurry Bio-
Reactor, and from the BATS will almost be mandatory to
provide the large amount of water for the soil washer and to
minimize the volume/mass of material requiring off-site
disposal. There remains some question, which may be site
and contaminant specific, to what extent water that is re-
cycled must be treated in the BATS.
Where a site requires cleanup of the soil, it is likely that
the groundwater below that site also is contaminated. Decon-
tamination of groundwater with the BATS may provide a
means of treating the groundwater and simultaneously pro-
viding the water needed for the soil washer. This can only be
determined after volumes and contamination levels of soils
and groundwater have been estimated.
Climate could play a small role in the effectiveness of
the BioTrol system, as it would with any biological treat-
ment. Significantly colder ambient temperatures can reduce
biological reaction rates. The BATS is equipped with a heat
exchanger and heater to minimize this effect and extremely
low ambient temperatures can be overcome by a small
increase in heat input, since most of the heat is reclaimed. In
addition, processing during very cold periods could encoun-
ter problems due to freezing of transfer lines and vessels. At
the MacGillis and Gibbs site in the late fall there was some
concern about freezing in the Slurry Bio-Reactor storage
tank. In a full-scale system, many of these concerns could be
readily overcome with heaters and heated lines.
Environmental Regulation Requirements
Under the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA) and the
Superfund Amendments and Reauthorization Act of 1986
(SARA), EPA is responsible for determining the methods
and criteria for the removal of waste and residual contamina-
tion from a site. The utility and cost effectiveness of the
BioTrol system would be dependent on the extent of decon-
tamination necessary for site restoration and the combination
of treatment units appropriate to achieve the required clean-
up levels for a particular site. If a waste exhibits a character-
istic hazard (e.g., toxicity) or is a listed hazardous waste
(newly promulgated wood preserving wastes: F032, F034,
and F035), treatment will be required. Since the level of
necessary decontamination has not yet been defined for the
MacGillis and Gibbs site, wood preserving sites in general,
nor, in a more generic sense, for pentachlorophenol, it is
unknown whether the washed soil or even the fine particle
cake treated in the Slurry Bio-Reactor would be acceptable
for return to the site as clean material. Similarly, without
such target levels, the benefits of additional treatment with
the BSWS (e.g., two passes through the soil washer) cannot
be assessed, nor can the cost of such increased (or decreased)
treatment be estimated. Nevertheless, since the use of reme-
dial actions by treatment that "...permanently and signifi-
cantly reduces the volume, toxicity, or mobility of hazardous
substances" is strongly recommended (Section 121 of SARA),
the BioTrol Soil Washer System would appear to be an
attractive candidate for remediation of sites contaminated
with hydrophobic organic chemicals.
SARA also added a new criterion for assessing cleanups
that includes consideration of potential contamination of the
ambient air. This is in addition to general criteria requiring
that remedies be protective of human health and the environ-
ment. Other than normal concerns for workers handling
large volumes of contaminated soils and the dust generated
during those operations, there appears to be minimal oppor-
tunity for exposure by workers or neighbors to the contami-
nants. Since the soil washing is a wet process, air emissions
are minimal. The companion demonstration on the BATS
established that no pentachlorophenol and only very low
levels of PAHs (maximum found: 2-methyl naphthalene at
47 ppb) are emitted to the ambient air.
Because of concern about dioxin and furan isomers as
byproducts in the production and degradation products of
chlorophenolics, these materials are strictly regulated. With-
out testing, it is impossible to state whether the treated and
untreated soil and fines from any site contaminated with
similar constituents would be suitable for landfill, incinera-
tion, or permanent disposal in another fashion. As a precau-
tion because of this concern over dioxins and anticipated
regulations at the outset of the project, the wastes generated
from this demonstration were containerized. Subsequent ana-
lytical testing of the MacGillis and Gibbs soil and product
fractions indicated that low concentrations of certain
chlorodioxins/ furans isomeirs (other than 2,3,7,8-TCDD)
were present. The levels are such that the soil and the output
fractions do not exceed the current dioxin listing criteria.
Additional regulatory aspects that would need to be
addressed include permits for wells that might be drilled to
treat groundwater (and provide water for soil processing)
and any excavation authorization that may be necessary.
Runoff from soil piles awaiting treatment may also need to
be treated in systems that themselves require permits. De-
pending on the size of the site being remediated and the roles
of the Slurry Bio-Reactor and BATS, storage tanks may be
necessary as reservoirs and to provide needed equalization.
Such tanks may need permits, spill contingency plans, etc.
depending on their size and whether they are above or below
ground. For a large site and a large soil washer system
processing masses such as 20 tons/hour, water storage ca-
pacity could be large enougli to require basins instead of
tanks. This would, of course, raise additional regulatory
questions about liners, secondary containment, leachate col-
lection, etc.
Even assuming that BATS-treated water would be re-
cycled during operation, discharge of the residual water and
decontamination of all equipment will be necessary at the
termination of operation. It is probable that the treated efflu-
16
-------
ent would be suitable for direct discharge or discharge to a
POTW as pretreated. A NPDES permit (or state equivalent)
would be required. While the SITE project is exempted from
permit requirements under the Resource Conservation and
Recovery Act of 1976 (RCRA), the Hazardous and Solid
Waste Amendments of 1984 (HS WA), and state regulations,
a commercial site will require a RCRA permit for the entire
treatment system, to operate as a hazardous waste treatment
facility. This would include storage tanks, all treatment
equipment/reactors, effluents, and if applicable, air emis-
sions.
Materials Handling Requirements
Soil Washer (SW)
Materials handling is a significant factor for both the
feed soil and the solid process streams. Prior to treatment,
conventional earth-moving equipment is needed to excavate
and screen (to
-------
Testing Issues
The GC/MS method for analysis of semivolatiles (EPA
Method 8270) was used to analyze all of the samples for this
demonstration because this is the only EPA-approved method
for pentachlorophenol that provides the desired mass spec-
trographic confirmation. It is a time consuming and costly
procedure. Because of the complexity of the procedure and
other factors, results were unavailable until several months
after the field demonstration was finished. Upon review of
these results, it became apparent that the Slurry Bio-Reactor
system never reached a steady state of operation during the
fourteen day test period. A method with more rapid turn-
around and on-site availability to assess process control
would have indicated that the test should be delayed until
acclimation had been completed and then extended until
steady-state operation was reached. BioTrol has developed a
faster HPLC procedure for liquids that may be useful to site
management and regulatory personnel for routine use. A
comparison of the BioTrol HPLC procedure and the EPA
method conducted as part of the companion demonstration
on the BATS indicated that the BioTrol method is accurate
for samples containing penta concentrations of 1 ppm or
higher. An immunoassay test for dissolved penta is under
development by EPA. It will allow rapid turnaround of
results with minimal experience.
In addition to the time factor, inefficiency in the GC/MS
extraction procedure was reflected in the Soil Washer mass
balances. For both the low penta and the high penta soil
washer tests, the mass balances for all materials achieved
good closure (ฑ9%), but the mass balances for penta indi-
cated an overall increase of +35% and +54%, respectively.
This apparent increase in overall penta mass may be attribut-
able to the extraction step of the GC/MS procedure. A
decision had been made to use sonication rather than soxhlet
extraction. It is suggested that extraction of the feed soils
was poor because the penta was tightly adsorbed/absorbed
by the soil matrix and in soil aggregates. Extraction of the
output solid streams was much more complete after the soil
washing operation made the penta more accessible and easier
to extract. The difficulties in obtaining meaningful, accurate
analyses of solid matrices is well known and efforts to
overcome such problems are ongoing. In retrospect, a study
of penta concentration changes with extraction time or a
shift to an alternate extraction procedure might have avoided
this problem.
Water inputs to the Soil Washer System were measured
using rotameters (which were already part of the BioTrol
system) during this demonstration. This involved obtaining
the rate of water input at several times and then calculating a
volume of water input during each time interval. The rota-
meters were hard to read accurately because the rate was
constantly fluctuating. The use of totalizers instead of rota-
meters would have made the measurement of water inputs
much easier and more accurate.
18
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Section 4
Economic Analysis
Introduction
The primary purpose of this economic analysis is to
estimate costs (excluding profit) for commercial-scale
remediation using the BioTrol mobile Soil Washing System.
With realistic costs and a knowledge of the bases for their
determination, it should be possible to estimate the economics
for operating similar-sized systems at other sites utilizing
scale-up cost formulas. Among such scale-up cost formulas
available in the literature for chemical process plant equip-
ment is the "six-tenths rule"1. Since the equipment used here
is not as complicated, this was modified to a "three-tenths
rule".
This economic analysis is based on assumptions and
costs provided by BioTrol, on results and experiences from
this SITE demonstration, and on best engineering judgement
as practiced by the authors. The results are presented in such a
manner that if the reader disagrees with any of the assump-
tions made here, other conclusions can be derived from such
other assumptions.
Although this demonstration tested three different tech-
nologies in a "system" configuration, BioTrol intends to mar-
ket equipment either separately or as an integrated system,
depending on a particular customer's needs. For the purposes
of this analysis, it is assumed that the commercial-scale sys-
tem utilizes the same three technologies evaluated in the
demonstration. It is also assumed that the performance of
commercial-scale equipment will be the same as that demon-
strated here.
Certain actual or potential costs were omitted because
site-specific engineering aspects beyond the scope of this
SITE project would be required. Certain functions were as-
sumed to be the obligation of the responsible party or site
owner and also were not included in the estimates. .
Cost figures provided here are "order-of-magnitude" esti-
mates, generally +50%/-30%, and are representative of charges
typically assessed to the client by the vendor exclusive of
profit.
The reader is also urged to obtain and review the Applica-
tions Analysis Report for the companion study, in which a
more extensive evaluation of the BATS and its economics
was carried out.
1 Perry, R.H., CWIIon, C.H., Chemical Engineer's Handbook, Fifth Ed., 1973, pg. 25-16.
Conclusions
The total cost to clean up 22,938 m3 (30,000 yd3) or
34,724 metric tons (38,273 short tons) of contami-
nated soil at the MacGillis and Gibbs Superfund site
using an 18.2 MT/hr (20 short ton/hr) soil washer,
three 378.5 L/min (100 gpm) aqueous treatment units
connected in parallel, and an 87 L/min (23 gpm)
slurry bioreactor would be about $185/metric ton
($168/short ton), including incineration of the fine
and coarse oversize woody debris from the soil
washer. If incineration costs were not included, this
would drop to $44/metric ton ($40/short ton).
The Soil Washer accounted for at least 90% of the
total cleanup cost primarily due to the incineration of
the fine and coarse woody debris.
Cost component distribution was highly technology
dependent Generally, labor and consumables and
supplies were two of the three largest cost compo-
nents, while startup and utility costs were one of the
smallest. On a percentage basis, equipment costs
were lowest for the Soil Washer, highest for the
SBR, and a relatively intermediate value for the
BATS. This was primarily due to the fact that the
SW incurred effluent treatment and disposal costs
whereas the BATS and SBR did not.
Unit costs in terms of individual process streams that
each technology in the system had to treat were as
follows:
SW $170/metric ton ($154/short ton)
or$257/m3($197/yd3)
BATS $0.44/1,000 L ($1.65/1,000 gal)
SBR $9.22/1,000 L ($34.39/1,000 gal)
The cost for the SW if incineration were not included
would drop to $29/metric ton ($27/short ton) or $44/m3 ($34/
yd3).
This information will help anyone considering using a
single technology to gauge the relative costs.
Two of the twelve cost categories as well as further
treatment and disposal of effluent from the BATS or
SBR were not considered in this economic analysis.
These factors could add substantially to the cleanup
19
-------
costs depending on permits and regulatory require-
ments, and site cleanup and restoration requirements.
These were considered to be the responsible party's
(or site owner's) obligation.
Issues and Assumptions
This section summarizes the major issues and assump-
tions used to evaluate the cost of BioTrol's soil treatment
system. In general, assumptions are based on information
provided by BioTrol. Certain assumptions were made to ac-
count for variable site and waste parameters and will, un-
doubtedly, have to be refined to reflect site specific conditions.
For purposes of this economic analysis, a hypothetical com-
mercial scale clean-up of the MacGillis and Gibbs Superfund
site was assumed.
Waste Volumes and Site Size
The volume of soil to be treated at the MacGillis and
Gibbs Superfund site has not yet been determined because
cleanup objectives have not yet been established. For the
purposes of this economic analysis, Mark Lahtinen, Project
Officer with the Minnesota Pollution Control Agency (MPCA),
has estimated the volume of contaminated soil to be approxi-
mately 22,938 m3 (30,000 yd3) with 10% moisture and a bulk
density of 1,682 kg/m3 (105 lb/ft3). The soil weight on a dry
basis is then 34,724 metric tons (38,273 short tons).
(20 ton/hr) mobile Soil Washing System (SW), three 378.5 L/
min (100 gpm) aqueous treatment system (BATS) units con-
nected in parallel, and an 87 L/min (23 gpm) Slurry Bio-
Reactor (SBR).
In the BATS, 1079 L/min (285 gpm) of process water
from the Soil Washer will be treated. A 1,325 L/min (350
gpm) circular thickener would precede the SBR. Only the
thickener underflow, at 87 L/min (23 gpm), is sent to the SBR.
The thickener overflow goes to dissolved air flotation for
further solids removal prior to recycle to the Soil Washer or
treatment in the BATS. A retention time of 5 days in the SBR,
similar to what was evaluated in the SITE program, was
assumed. On these bases, the required total reactor volume
was calculated to be 627,175 L (165,700 gal). This volume
would be assembled as three parallel trains of three reactors in
series, each with a volume of 68,130 L/reactor (18,000 gal-
lons/reactor). The fine solids coming out of the SBR are
assumed to be clean enoug;h to be returned to the site. The
washed soil is also assumed to be clean enough to be returned
to the site without further treatment, although it is recognized
that clean up objectives not yet established would have to be
satisfied.
The only residuals from the Soil Washer requiring treat-
ment consist of fine and course oversized woody debris. It is
assumed that these will be incinerated off-site and the esti-
mated cost has been included with the SW costs.
System Design and Performance Factors
Figure 7 shows a simplified flowsheet of BioTrol's com-
mercial Soil Washing System (BSWS) proposed for the cleanup
of the MacGillis and Gibbs site. It consists of an 18.2 MT/hr
Food Soil
20.0 TPH (Dry)
>
Oversize *
(Mostly Wood)
1.9TPH(Dry)
\
Unspecified
Treatment or
Disposal
Soil
Washing
System
1
\
Washed Soil
16.9 TPH (Dry)
I
Fine Particle
Slurry
1.3TPH(Dry)
I
Slurry
Bioreactor
\
Dewatering
\
Fine Particle
Cake
1.3TPH(Dry)
^
Process Water
285 GPM
}
Aqueous
Treatment
System
\
Recycle to
Soil Washing
System
' Includes both fine and coarse oversize
Figure 7. Simplified Treatment Flowsheet for MacGillis and
Gibba Soil.
System Operating Requirements
Tables 8 and 9 summarize the SITE demonstration soil
washing mass balance data for the "low penta" and "high
penta" concentration tests, respectively. Total wet weights of
all process streams were adjusted to a dry weight basis using
percent solids data. On a dry weight basis, the two soils
behaved similarly.
Mass flow rate calculations for a 18.2 MT/hr (20 ton/hr)
soil washing system are summarized in Table 10. A mean
value of product dry weights for the "low penta" and "high
penta" concentration tests were used. The product dry flow
rates were estimated by multiplying the 18.2 MT/hr (20 ton/
hr) feed soil rate into the Soil Washer by the appropriate dry
weight percent. The percent solids level is BioTrol's reason-
able expectation in a commercial system. It should be noted
that these numbers are not necessarily reflective of the pilot-
scale operation demonstrated in the SITE program. The wet
flow rates are calculated by dividing the dry flow rates by the
appropriate solids percent. Process water flow rate was deter-
mined by a proprietary mathematical model developed by
BioTrol.
It was assumed that the soil washing system would oper-
ate 24 hours per day (three 8-hour shifts per day), 7 days per
week. Four crews of four would be assigned to a standard shift
rotation schedule, with each person working 40 hours per
week, with 8 overtime houirs during each 4 week rotation.
Twenty hours per week (4 hours per shift) of the lead opera-
tors' time would be devoted to the biological treatment sys-
tems. The remaining 22 houirs per week would be devoted to
the Soil Washer. A maintenance mechanic is scheduled to be
20
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Table 8. Soil Washing System Mass Balance Low Penta Soil
Process Stream
Feed Soil
Washed Soil
Coarse Oversize
Fine Oversize
Fine Particle Cake
Total Products
Table 9. Soil Washing
Process Stream
Feed Soil
Washed Soil
Coarse Oversize
Fine Oversize
Fine Particle Cake
Total Products
Total
Wet Weight
kg (Ib)
11,204
(24,700)
12,928
(28,500)
1,588
(3,500)
635
(1,400)
2,359
(5,200)
System Mass Balance - High
Total
Wet Weight
kg (Ib)
17,554
(38,700)
22,816
(50,300)
3,130
(6,900)
998
(2,200)
3,924
(8,650)
Mean
Solids
(Percent)
89
74
68
10
31
Penta Soil
Mean
Solids
(Percent)
83
70
51
16
33
Total
Dry Weight
kg (Ib)
9,957
(21,950)
9,526
(21,000)
1,089
(2,400)
66
(145)
726
, (1,600)
11,406
(25,145)
Total
Dry Weight
kg(lb)
14,570
(32,120)
15,967
(35,200)
1,588
(3,500)
159
(350)
1293
(2,850)
19,006
(41,900)
Dry Weight
(Percent of
Products)
87.1
83.6
9.5
0.6
6.4
Dry Weight
(Percent of
Products)
76.6
84.0
8.4
0.8
6.8
Table 10. Estimated Product Flow Rates from Soil Washing 18.2 MT/Hr (20 Tons/Hr) Treatment of MacGillis and Gibbs Site
Dry
Weight
Process Stream (%)
Feed Soil 100.0
Washed Soil 83.8
Oversize'" 9.6
Fine Particle Slurry 6.6
Process Water <2> NA
Dry Flow
MT/hr Solids
(ton/hr) (%)
18.2 90.0
(20.0)
15.3 90.0
(16.8)
1.7 50.0
(1.9)
1.2 20.0
(1-3)
NA 0.0
Wet Flow
MT/hr
(ton/hr)
20.2
(22.2)
17.0
(18.7)
3.4
(3.8)
5.9
(6.5)
64.7
(71.3)
L/min
(gal/min)
NA
NA
NA
24
1079
(285)
Notes: (1) Includes both coarse and fine oversize products (predominantly wood). <-nol, - ,.oc. *Kn u \ ซt,Q
(2) Includes only water requiring treatment - the total recycle water flow rate is about 1609 to 1703 Umin (425 to 450 gal/mm), the
balance of recycled process water will be used untreated at the front end of the process.
21
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on the day shift, 5 days per week. The 12 operators that would
be required would be hired locally. Labor rates include sala-
ries, benefits, administration/overhead costs, and per diem
living expenses and rental car costs for non-local personnel.
Utilization Rates and Maintenance Schedules
It would take about 80 days to treat 34,724 metric tons
(38,273 short tons) at 18.2 MT/hr (20 tons/hr). To account for
both scheduled maintenance and unscheduled shutdowns, a
10% downtime was judged to be adequate. This would result
in an actual treatment time of 89 days or roughly 13 weeks.
Scheduled maintenance would be performed by a mainte-
nance mechanic during the day shift. Two weeks for mobiliza-
tion and training and one week for demobilization were added
to the treatment time for a total time on site of 110 days (16
weeks).
Financial Assumptions
For the purpose of this analysis, capital equipment costs
were amortized over a 10 year period with no salvage value.
Interest rates, time-value of money, etc. were not taken into
account because the clean up time (4 months) is so short.
Basis for Economic Analysis
In order to compare the cost-effectiveness of technolo-
gies in the SITE program, EPA breaks down costs into 12
categories shown in Table 11 using the assumptions already
described. The assumptions used for each cost factor are
described in more detail below.
Site Preparation Costs
The amount of preliminary preparation will depend on
the site and is assumed to be performed by the responsible
party (or site owner). Site preparation responsibilities include
site design and layout, surveys and site logistics, legal searches,
access rights and roads, and preparations for support facilities,
decontamination facilities, utility connections, and auxiliary
buildings. These preparation activities are assumed to be
completed in 500 staff hours. At a labor rate of $50/hr this
would equal $25,000 as shown in Table 11.
Permitting and Regulatory Costs
Permitting and regulatory costs are generally the obliga-
tion of the responsible party (or site owner). These costs may
include actual permit costs, system health/safety monitoring,
and analytical protocols. Permitting and regulatory costs can
vary greatly because they are very site- and waste-specific. No
permitting costs are included in this analysis; however, de-
pending on the treatment site, this may be a significant factor
since permitting can be an expensive and time-consuming
activity.
Equipment Costs
Capital equipment costs are broken down into the three
technologies demonstrated under the SITE program, i.e., Soil
Washer (SW), BioTrol Aqueous Treatment System (BATS),
and Slurry Bio-Reactor (SBR). For comparison purposes,
equipment costs for all three technologies have been amor-
tized over 10 years and it is sissumed there is no salvage value
at the end of the 10 year period.
Soil Washer
Soil washing is not an "off the shelf process and must be
modified for site specific conditions on a case-by-case basis.
Factors such as contaminant type and level, cleanup criteria,
soil mineralogy, and soil particle size distribution must be
considered when designing a treatment system. The soil is
first characterized to determine the nature and location of the
contaminants. A strategy is then developed to effect the
separations necessary to achieve the volume reduction re-
quired to meet regulatory goals. This is accomplished by
concentrating the contaminants in a small volume of material
while producing a washed soil product meeting appropriate
cleanup criteria. The number, size and type of unit operations
required to accomplish the n
-------
Table 11. Estimated Costs for MacGillis and Gibbs Site
Cost Component SW %
BATS
SBR
Total
5,897,000
100
60,195
100
101,450
100
Total
1 . Site Preparation Costs
2. Permitting & Regulatory Costs
3. Equipment Costs
(amortized over 10 years)
4. Startup
5. Labor
6. Consumables and Supplies
Health & Safety Gear
Maintenance Supplies
Flocculant
Fuel (for front end loader)
Nutrient
Caustic
Defoamer
7. Utilities
Tel.
Elec.
Sewer/Water
8. Effluent Treatment & Disposal
9. Residuals/Waste Shipping,
Handling and Transport Costs
10. Analytical Costs
11. Facility Modification,
Repair & Replacement
1 2. Demobilization Costs
N/A
125,000
10,000
387,100
11,500
41,300
331 ,200
4,300
800
98,600
7,200
4,870,000
10,000
N/A
2 11,840
4,350
6 16,000
5,750
1 5,900
6
1,225
8,540
2,190
700
2 2,870
83
'
830
20
.
7
27
9
10
2
14
4
1
5
1
N/A
46,660 46
4,350 4
16,000 16
5,750 6
11,800 12
500
590
700 1
11,500 11
3,600 4
25,000
N/A
183,500
18,700
419,100
23,000
59,000
331,200
4,300
1,725
8,540
2,780
2,200
112,970
7,200
4,870,000
282,000
53,400
14,430
3
7
1
5
2
76
5
1
6,419,045
100
Table 12. Soil Washer Capital Equipment Cost Analysis
Equipment List
1 . Hopper
2. Conveyor [
3. Bucket Elevator
4. Trommel
5. Mesh Screen
6. Dewatering Screen
7. Pump
8. Froth Flotation Tank
9. Attrition Tank
1 0. Classifier
1 1 . Centrifuge
1 2. Thickener
Indexed Total Equipment Cost
Quantity
1
4
1
1
2
1
10
2
2
3
1
1
Equipment
Unit Cost*
($)
2,0002(1986)
3,0002(1981)
3,0002(1981)
3,000s (1981)
2,500' (1986)
2,500' (1986)
1, 0003(1991)
100,0001(1978)
100,000' (1978)
15,000' (1982)
700,000' (1982)
100,000' (1978)
Equipment
Total Cost
($)
2,000
12,000
3,000
3,000
5,000
2,500
10,000
200,000
200,000
45,000 ,
700,000
100,000
Cost Index8
4231
3384
3384
3384
4231
4231
4773
2693
2693
3721
3721
2693
Index Ratio0
1.13
1.41
1.41
1.41
1.13
1.13
1.00
1.77
1.77
1.28
1.28
1.77
Ancillary Equipment & Assembly Labor
Grand Total Equipment Cost
Indexed
Equipment Costs
($)
2,300
17,000
4,200
4,200
5,700
2,800
10,000
350,000
350,000
58,000
900,000
180,000
1,900,000
950.000
2,850,000
A. Number in parentheses indicates year that cost figure was obtained for. Superscript indicates source of information as follows:
1. K. Wagner, et al, "Remedial Action Technology for Waste Disposal Sites", 2nd ed., Noyes Data Corp., 1986.
2. Equipment costs were judged to be similar to equipment found in Source 1.
3. From past purchasing experience.
B. Assumed to be for month of March in year of interest.
C. Index Ratio = Cost Index for 1991 (4773) divided by Cost Index for year of interest.
23
-------
This value was independently verified using cost figures
given in reference 1 of Table 12 for activated sludge treatment
units. A construction cost of $82,000 (in 1984 dollars) for a
379 L/min (100 gpm) unit was linearly interpolated between a
265 L/min (70 gpm) unit ($78,500) and a 530 L/min (140
gpm) unit ($85,600), using the same ENR cost indices as were
used in Table 12. This $82,000 in 1984 dollars (cost index - 3/
84 ~ 4118) is $95,000 in 1991 dollars (cost index - 3/91 =
4773). Therefore three units would cost approximately
$285,000. As noted earlier, cost savings could be realized by
cdmbining some systems.
The $250,000 cost, amortized over a 10 year equipment
life span, amounts to $2,085/month or $8,340 for the 16 week
total treatment time.
Slurry Bio-Reactor
Capital cost data for full-scale slurry reactors were pro-
vided to BioTrol by EIMCO Process Equipment Co. of Salt
Lake City, Utah, which supplied the pilot-scale slurry reactors
used in the SITE demonstration. The only major piece of
equipment that would be added to the pilot-scale unit would
be a 1,325 L/min (350 gpm) circular thickener before the
SBR. The thickener overflow would go to dissolved air flota-
tion for further solids removal prior to treatment in the BATS.
The thickener underflow at 87 L/min (23 gpm) would be sent
to the bioreactors. For a 5 day residence time, this would
require a total reactor volume of 625,000 L (165,700 gal).
To provide the required reactor volume, nine transport-
able 68,130 L (18,000 gallon) reactors would be assembled as
three parallel trains of three reactors in series. Based on
information supplied by EIMCO, the total estimated capital
cost for the slurry treatment system and ancillary equipment
(blowers, thickener, splitter box, transfer pump, piping, in-
strumentation, and electrical) is $1.1 million.
As far as it could be determined, EIMCO is the only
company manufacturing these types of slurry bioreactors.
Hence, there was no independent way to verify costs. Instead,
EIMCO's estimate was checked against a price quote given
for another SITE project for a different size reactor. The
"three-tenths factor" for different sized equipment was then
applied to determine if their price was reasonable. EIMCO
quoted a price of $28,000 for a 450 L (120 gal) reactor2. To
estimate the cost of a 68,130 L (18,000 gal) reactor, the
following "three-tenths factor" was used:
where Ca is the new equipment cost, C is the previous
equipment cost, and r is the ratio of new to previous .capacity.
Therefore:
Ca s 68.130 L " ($28,000) = $125,000
450 L
For nine reactors, this would total $1.1 million; which
confirms EIMCO's estimate. Monthly equipment costs amor-
tized over 10 years is $9,165 or $36,660 for the 16 week total
treatment time.
Additional equipment to operate the facility is presumed
to include a field office trailer, decontamination trailer, and
front end loader. The total cost is approximately $38,500,
which has been apportioned among the three technologies in
the following manner: $25,000-SW, $3,500-BATS, $10,000-
SBR.
Startup
All three of BioTroPs technologies are mobile units
designed to move from site to site. Transportation costs are
only charged to the client for one direction of travel and are
usually included with mobilization rather than demobiliza-
tion. Transportation costs are variable and dependent on site
location as well as on'applicable oversize/overweight load
permits, which vary from state to state. The total cost will
depend on how many state lines are crossed.
Assembly is a labor intensive operation consisting of
unloading equipment from trucks and trailers used for trans-
portation, as well as actual assembly. It is estimated that
mobilization and training would take about 2 weeks and this
time is included in the total time on site (110 days). The
startup labor cost is included in the total labor cost component
and includes living expenses.
The cost of monitoring programs has been broken down
into two components - OSHA training* estimated at $4,300,
and medical surveillance, estimated at $14,400. The total cost
of $18,700 has been apportioned among the three technolo-
gies in the following approximate mariner: 50%-SW, 25%-
BATS, 25%-SBR. Depending on the site, however, local
authorities may impose specific guidelines for monitoring
programs. The stringency and frequency of monitoring re-
quired may have significant impact on the project cost.
Labor
Labor costs may be broken down into two major catego-
ries: salaries and living expenses. Living expenses for all on-
site personnel consist of per diem and rental cars, both estimated
at 7 days/week for the entire time spent on-site (110 days). Per
diem is assumed to be $125 per day per person, but may vary
widely by location. Three rental cars are assumed to be
obtained at a rate of $55/day. The per diem and car rental costs
have been included under the Soil Washer technology.
Supervisory and administrative staff will consist of an
off-site program manager and an on-site project manager.
Professional and technical staff will consist of a project engi-
neer and crew of four with 1 lead operator and 3 operators.
The soil treatment system will operate 24 hours per day (3-8
hours shifts per day), 7 days per week. Four crews will be
assigned to a standard shift .rotation schedule, with each
person working 40 hours per week and 8 overtime hours
during each 4 week rotation. A maintenance mechanic is also
scheduled 5 days per week on the day shift. The soil washing
labor requirements and rates are detailed in Table 13.
Note that each operator is shown to work an average of 42
hours per week (one overtime shift every 4 weeks). Also, each
lead operator will devote 22 hours per week to the Soil
' Personal communication. Dr. Derek Ross. ERM INC., Exlon, PA. July 18.1991
24
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Table 13. Soil Washing Labor Requirements and Rates
Position
Program Manager
Project Manager
Project Engineer
Lead Operator
Operator*2'
Mechanic
Total
Number
of People
1
1
1
4
12
1
20
Hours
Per Week
8
40
40
22
42
40
Rate'1'
($ Per Hours)
52.50
42.50
35.00
25.00
20.00
25.00
Notes: (1) Includes salary, benefits, and administration/overhead
costs but excludes profit.
(2) This position will be filled by persons hired locally.
Washer and the remaining 20 hours per week to the biological
systems (4 hours per shift - 2 hours for the BATS and 2 hours
for the SBR).
Consumables and Supplies
There are two items that are common to all three tech-
nologies. These are health and safety gear which include hard
hats, safety glasses, respirators and cartridges, protective cloth-
ing, gloves, safety boots, and aphotoionization detector moni-
tor, all estimated at $23,000. This cost has been apportioned
among the three technologies in the following manner: 50%-
SW, 25%-BATS, 25%-SBR. The second item is maintenance
supplies (spare parts, oils, greases and other lubricants, etc.)
estimated at $59,000. This cost has been apportioned among
the three technologies in the following manner: 70%-SW,
10%-BATS, 20%-SBR.
Soil Washer
The amount of flocculant consumed in thickening can
vary from 0.2 to 2.3 kg (0.5 to 5 Ib) of flocculant per ton of
soil (dry) depending on the soil characteristics and contami-
nants. An average flocculant usage rate of 1.4 kg per ton (3
pounds per ton) of soil has been assumed here. Flocculant cost
can range from $3.30 to $6.60 per kg ($1.50 to $3.00 per
pound). A conservative figure of $6.34/kg ($2.88/lb) was
assumed to arrive at the total cost of flocculant consumed,
$331,200.
Diesel fuel for the front end loader is estimated at $39/
day for the full 110 day treatment period resulting in a cost of
$4,300.
BioTrol Aqueous Treatment System
The cost for nutrient is based on a commercially available
liquid fertilizer formulation of 25% nitrogen and 5% phospho-
rus added to achieve a COD:N:P ratio of 100:5:1. Using 47 L/
day (12.5 gal/day) at a cost of $0.29/L ($1.10/gal) would yield
$13.75/day or $1,225 for the 89 day treatment period.
Caustic usage would be determined by the pH and alka-
linity of the incoming water to be treated. For purposes of this
cost estimate, usage was assumed to be the same as that
demonstrated under this SITE project [0.34 L (0.09 gal) of
50% solution per 3,785 L (1000 gal) of water treated]. More
or less caustic may be required at another site; however,
caustic use should remain essentially constant throughout the
treatment of a specific waste. For a commercial scale cleanup,
a cost of $0.69/L ($2.60/gal) of 50% solution was assumed.
Thus, the cost would be $0.06/1000 L ($0.24/1000 gal) of
water or $8,540 to treat 138 x 10s L (36.5 x 10s gal).
Use of a standard wastewater treatment defoamer at a
concentration of 5 ppm and cost of $3.17/kg ($1.44/lb) was
assumed. Total defoamer cost would be $2,190 for 89 days of
treatment.
Slurry Bio-Reactor
The costs of consumables and supplies for biological
slurry treatment are similar to those for biological water
treatment Nutrients are assumed to be added at a rate of 19 L/
day (5.1 gal/day). If the cost is once again assumed to be
$0.29/L ($1.10/gal), the total treatment cost would be $500 for
89 days.
Defoamer and acid or caustic for pH control are assumed
to be added together. A cost of $0.05 per 1000 L ($0.20 per
1,000 gal) of slurry was taken as an estimated average based
on results from previous laboratory treatability studies. There-
fore, the cost to treat 11 x 106 L (2.95 x 10s gal) of slurry
would be $590.
Utilities
Telephone charges are estimated at $500/month plus an
additional 10% for fax service or $550/month. This will total
$2,200 for the 110 days (4 months) spent on-site. This number
has been apportioned approximately equally among the three
technologies.
Soil Washer
BioTrol estimated that unit operations for an 18.2 MT/hr
(20 ton/hr) Soil Washer would correspond to 1030 horse-
power. At $0.06/kw-hr, electricity usage would cost approxi-
mately $98,600 for 89 days of treatment.
Since the process water is assumed to be recycled back to
the soil washer, very little make-up water would be required.
Water usage by site personnel was estimated to be 115 L/day/
person (30 gal/day/person). If 20 people a day are assumed to
be at the site, then the daily water usage would be 2,270 L
(600 gal) or 250,000 L (66,000 gal) for the 110 day duration
of treatment. Assuming combined sewer and water usage
costs $0.05 per 1,000 L ($0.02 per 1,000 gal), this would
amount to an inconsequential cost of about $15.
Aqueous Treatment System
The electrical demand for the BATS was estimated by
BioTrol to be about 30 horsepower. At a cost of $0.06/kw-hr,
the total cost of electricity would be $2,870.
25
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Slurry Bio-Reactor
The electrical demand was estimated by BioTrol to be
about 120 horsepower. Using the same cost of electricity as
above would yield a cost of $11,500.
Effluent Treatment and Disposal
The process water treated in the BATS will be recycled to
the Soil Washer. Hence, no disposal costs are associated with
the process water stream.
The fine particle cake resulting from dewatering the SBR
effluent is assumed to meet local, state or federal requirements
for return to the site. Hence, no disposal costs are associated
with the fine particle slurry stream.
The fine and coarse oversize streams coming off the Soil
Washer do need to be treated. It was assumed that incineration
would be used to dispose of these effluent streams. Incinera-
tion costs were derived from the demonstration test. Two
hundred fifty - 208 L (55 gal) drums of fine and coarse
oversize debris were generated during the test program. As-
suming the waste has a density of 2400 kg/m3 (20 Ib/gal), each
drum would weigh about 500 kg (1000 Ib). Preliminary pric-
ing prior to acceptance and approval by the incinerator facility
was approximately $600/drum. Hence, it would cost$150,000
to incinerate 125 tons of debris or $1200/ton.
Using this figure for the commercial-scale clean-up the
cost to treat 1.9 tons/hr of fine and oversized debris for 89
days would be about $4.87 million.
Residuals/Waste Shipping, Handling and
Transport Costs
Waste disposal costs including storage, transportation
and treatment costs are assumed to be the obligation of the
responsible party (or site owner). It is assumed that residual or
solid wastes generated from this process would consist only of
contaminated health and safety gear, used filters, spent acti-
vated carbon, etc. Landfilling is the anticipated disposal method
for this material and costs were once again derived from the
demonstration test Fifty-five 208 L (55 gal) drums of waste
were generated during the demonstration test. Assuming this
waste has a density of 1200 kg/m3 (10 Ib/gal), each drum
would weigh about 250 kg (500 Ib). The cost to landfill these
drums by the same disposal facility that would be used to
incinerate the penta-contaminated woody debris was given as
S180/drum. Hence, it would cost $9,900 to landfill 15 tons of
waste or $660/ton.
Based on the demonstration test, it was assumed that the
amount of residual waste would be about 10% of the effluent
stream. For the commercial-scale cleanup this would amount
to about 0.2 tons/hr for 89 days. Using the above cost figure of
S660/ton, the cost for residuals handling, shipping, and trans-
port is estimated to be $282,000.
Analytical Costs
Standard operating procedures for BioTrol do not require
planned sampling and analytics J activities. Periodic spot checks
may be executed at BioTrol's discretion to verify that equip-
ment is performing properly and that cleanup criteria are
being met, but costs incurred from these actions are not
assessed to the client. The client may elect, or may be required
by local authorities, to initiate a sampling and analytical
program at their own expense,
For this'cost analysis, one sample per day for 89 days at
$600/sample was assumed to Ibe required by local authorities
for monitoring and permitting purposes. This would total
approximately $53,400 for the 13 week test period.
Facility Modification, Repair and Replacement
Costs
Since site preparation costs were assumed to be borne by
the responsible party (or site owner), any modification, repair,
or replacement to the site was also assumed to be done by the
responsible party (or site owner). These costs were assumed
not to exceed 10% of the respective technology's capital costs
and are so indicated on Table 11.
Demobilization Costs
Site demobilization will include shutdown of the opera-
tion, final decontamination amd removal of equipment, site
cleanup and restoration, permanent storage costs, and site
security. Site demobilization costs will vary depending on
whether the treatment operation occurs at a Superfund site or
at a RCRA-corrective action site. Demobilization at the latter
type of site will require detailed closure and post-closure
plans and permits. Demobilization at a Superfund site does
not require as extensive post-closure care; for example, 30-
year monitoring is not required. This analysis assumed site
demobilization costs are limited to the removal of all equip-
ment and facilities from the site. It is estimated that demobili-
zation would take about one week and this is included in the
total time on site (110 days). Labor costs include salary and
living expenses. See "Labor Costs" for information on labor
rates.
Grading or recompactiojti: requirements of the soil will
vary depending on the future rase of the site and are assumed
to be the obligation of the resjxmsible party (or site owner).
Results
Table 11 shows the total cleanup cost to be $6.4 million
itemized by cost category and technology. It should be noted
that the dollar totals for each technology do not add up to the
total cleanup cost because some cost categories (i.e., site
preparation, analytical, and residuals/waste shipping, han-
dling and transport costs) were not distributed among the
different processes. Nevertheless, of the total cost, at least
90% can be attributed to the Soil Washer. The main factor for
this is that the fine and coarse oversized woody debris from
the Soil Washer were assumed to be incinerated. Although
these streams represent less than 10% of the total product, the
26
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cost for their disposal represents over 80% of the cost of
cleanup associated with the Soil Washer. Hence, it can be
observed from Table 11 that the cost distribution is highly
dependent on the technology. The next largest cost compo-
nents are labor (6%), and consumables and supplies (7%)
followed by equipment costs (2%), and utilities (2%).
For the BATS, the largest cost component is consumables
and supplies (39%), followed in order by labor (27%), equip-
ment (20%), startup (7%), and utilities (6%). For the SBR,
equipment costs (46%) were followed in order by consumables
and supplies (18%), labor (16%), utilities (12%), facility
modification, and startup each at4%. Labor, and consumables
and supplies were two of the three largest cost components,
while startup, utility, and facility modification costs were
generally one of the smallest cost components. Interestingly,
on a percentage basis, equipment costs were lowest for the
Soil Washer, highest for the SBR, and at a relatively interme-
diate value for the BATS. This was primarily due to the fact
that the SW incurred effluent treatment and disposal costs
(woody debris incineration) whereas the BATS and SBR did
not.
Based on 34,724 metric tons (38,273 short tons) of con-
taminated soil treated, the total unit cost is $185/metric ton
($168/short ton). If the cost of incineration were not included,
the cost would drop to $44/metric ton ($40/short ton). The
breakdown by technology is shown below:
Soil Washer
Aqueous Treatment System
Slurry Bioreactor
Total
Unit Cost
(I/metric ton) (I/short ton)
$170.00
$1.73
$2.92
$174.65
$154.00
$1.57
$2.65
$158.22
metric ton ($158/short ton) represents other cost components
that were not included in each technology (i.e., site prepara-
tion, analytical, and residuals/waste shipping, handling and
transport costs). However, these additional components ac-
count for only about 5% of the costs based on $/ton and would
not have had a significant impact
As stated in the introduction to this section, BioTrol
intends to market its technologies both independently of one
another as well as in an integrated system as demonstrated
here. It is therefore instructive to express unit costs not in
terms of total soil treated in the front end of the system but
rather in terms of individual process streams that each tech-
nology in the system had to treat. For the Soil Washer this is
still $170/metric ton ($154/short ton) or $257/m3 ($197/yd3)
(based on 22,938 m3 (30,000 yd3) treated). If incineration
were not included this would drop to $29/metric ton ($27/
short ton) or $44/m3 ($34/yd3).
For the BATS, 1079 L/min (285 gpm) of process water is
assumed to be treated for 89 days for a total of 138 x 106 L
(36.5 x 106 gal). The BATS treatment unit cost is then
calculated to be $0.44/1000 L ($1.65/1,000 gal): ($60,195 +
138 x 103 L (36.5 x 103 gal)). For the SBR, 87 L/min (23 gpm)
of a 20% solids slurry is assumed to be treated for 89 days for
a total of 11 x 106 L (2.95 x 10s gal). The SBR treatment unit
cost is then calculated to be $9.22/1,000 L ($34.89/1000 gal):
($101,450 -i-11 x 103 L (2.95 x 103 gal)).
In all of the above analyses, it should be remembered that
costs for 10 out of the 12 cost components were considered.
One of the cost components not included here was permitting
and regulatory expenses. Additionally, effluent treatment and
disposal for the BATS and SBR were assumed not to be
required. If these factors are taken into account, costs could
significantly increase.
The difference in cost figures between the total unit cost
of $185/metric ton ($168/short ton) and the above $175/
27
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Section 5
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ON PENTACHLOROPHENOL METABOLISM BY
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FLAVOBACTERIUM SPECIES, Applied and
Environmental Microbiology, Oct. 1988, p. 2452-
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Torpy, M.F., H.F. Stroo, and G. Brubaker, BIOLOGI-
CAL TREATMENT OF HAZARDOUS WASTE,
Pollution Engineering, May 1989, p. 80 ff.
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Document #120-86-414 for Minnesota Pollution
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CLASSIFICATION SYSTEM, Technical Memoran-
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Valine, S.B. and D.D. Chilcote, BIOTROL SOIL
WASHING SYSTEM, presented at SITE meeting,
Philadelphia, PA, May 1990.
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30
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Appendix A
Process Description
Introduction
Previous tests conducted by BioTrol indicate that most
soil contaminants usually are associated with the fine particle
fraction (below 0.075 mm) of a bulk soil. Separation of the
fines fraction concentrates the contaminants into a small
portion of the original sdil, which greatly reduces the amount
of material requiring disposal or further treatment.
The Soil Washer (SW) separates slightly contaminated,
coarse, washed soil particles from heavily contaminated fine
particles. Solubility of contaminants in the processing water
can also be a significant factor in the ultimate distribution.
The fine particles may be treated in the Slurry Bio-Reactor
(SBR), which reduces contaminant concentration by biologi-
cal destruction. The process water used in the SW is treated in
the BioTrol Aqueous Treatment System (BATS) prior to
discharge or recycle. The actual arrangement and operation of
the individual technologies will depend on site characteristics
and the contaminants present. All three technologies operate
in continuous feed mode. However, the SBR used in the
demonstration was considerably smaller in capacity than ei-
ther the SW or the BATS.
Process Description
Soil Washer
The SW is an intensive, countercurrent scrubbing system
for treating excavated contaminated soils. The process flow
diagram is shown in Figure A-l. Following excavation, large
debris is removed from the soil by a vibrating screen. The
remaining soil is fed via conveyor to a mixing trommel where
it is mixed with water to form a slurry. The slurry flows from
the mixing trommel and passes across a vibrating screen
where oversize (CO) material is removed. The coarse oversize
product is stored in drums for disposal. The screen undersize
product is fed to a flotation unit where hydrophobic constitu-
ents are removed in a froth phase. Underflow then enters an
intensive, multi-stage, countercurrent scrubbing circuit con-
sisting of attrition and classification equipment The intense
scrubbing action of the attrition equipment disintegrates soil
agglomerates and separates "piggybacking" fines from the
coarser particles. Abrasion between the coarser particles pro-
vides additional cleaning of their surfaces. The classification
equipment separates the fines from die coarse soil particles.
The fine clays and organic matter retain considerable amounts
of contaminants, even after undergoing intensive attrition
scrubbing. The fine soil particles, which are suspended in the
process water from the scrubbing circuit, are fed to a thicken-
ing operation along with the froth from the flotation unit. Just
before thickening, a polymeric flocculating agent is added to
the slurry of fine particles to improve settling and separation
from the process water. The thickened solids (underflow) are
then dewatered using a horizontal centrifuge to form a fine
particle cake (FPC) which is drummed for disposal. The FPC
contains most of the organic contaminants from the feed soil
and requires further treatment, for which the Slurry Bio-
Reactor was evaluated, using the fine particle slurry prior to
thickening or dewatering. Process water from thickening and
dewatering processes is sent to the BATS for treatment
Slurry Bio-Reactor
The EIMCO Slurry Bio-Reactor (SBR) is a microbiologi-
cal system for degrading penta and PAHs absorbed or adsorbed
on the surface of organic and clay particles. BioTrol used the
SBR to remove contamination from the clay and silt from the
SW.
Oversize Debris
Coarse Oversize
and
Fine Oversize
Contaminated
Soil
Combined
Dewatering
Effluent
Initial Screening -
and
Attrition/
Classification
Circuit
Washed
Soil
Product
\
Aqueous
Treatment
System
(;
Fine Silts,
Clays, and
Organics
Treated
Fine
Particle
Slurry
Water
Storage
Tanks
Recycled Process Water
Figure A-1. Flow Diagram of the BioTrol Soil Washing System
(BSWS).
31
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The pilot-scale SBR (Figure A-2) which was provided by
EIMCO for the demonstration consists of three upright, con-
tinuously stirred, stainless steel reactors in series, each with a
capacity of 60 liters (16 gallons). Each one is a modified
thickener incorporating an airlift which pumps settled solids
that have been raked to the center column back to the top and
redistributes them. Flexible membrane diffusers mounted on
stainless steel rotating rake arms provide fine bubble aeration
and turbulence for mixing with minimal shear. The membrane
diffusers are of a non-clog type made of an elastomeric
material which is chemically resistant to the contaminants.
The reactors are gas sealed and all gases are vented through an
activated carbon canister to prevent emission of organic com-
pounds into the environment
The three reactors are arranged in a cascading system,
permitting gravity feed and overflow. The slurry enters the
first reactor where easily degraded contaminants are con-
sumed by the pre-inoculated and acclimated microbial popu-
lation. As the slurry flows to each successive tank, the more
refractory contaminants are eventually broken down. Vari-
ables that must be controlled for proper operation of the Slurry
Bio-Reactor system include: suspended solids concentration,
pH, nutrient concentrations, influent flow rate, temperature,
dissolved oxygen concentration, gas flow rate, and rake arm
speed.
The influent flow rate is controlled by a variable speed
peristaltic pump. The system is equipped with automatic
temperature control. The dissolved oxygen concentration is a
function of the gas flow rate, the oxygen concentration in the
gas, and the rate of intake by the microorganisms. The dis-
solved oxygen concentration is controlled by the air flow rate
and is measured using a dissolved oxygen probe. All gas flow
rates are monitored by rotameter. The rake arm speed is
controlled by a variable speed drive.
The reactor system is best operated at steady-state to
minimize operator attendance and maximize the biological
degradation rate.
v
BioTrol Aqueous Treatment System
The BioTrol Aqueous Treatment System (BATS) is a
multi-cell, submerged, packed-bed reactor which serves to
biologically degrade penta- and PAH-contaminated process
water from the SW. The system used in this demonstration
consists of a single trailer (20 ft) on which all the vessels,
pumps, etc. for the entire process are installed (Figure A-3).
The process flow is shown in Figure A-4. Incoming
wastewater is pumped on a rime cycle to a 100 gallon temper-
ing tank inside the trailer. In; the tempering tank, the pH of the
contaminated water is adjusted to approximately 7.3 by the
addition of caustic or acid and a concentrated nutrient mixture
of trisodium phosphate and urea dissolved in water is metered
in.
From the tempering tank the stream is pumped to the base
of the first of three cells in the bioreactor by passing under an
influent baffle and through the heat exchanger (see Figure A-
4). Each of the three cells is filled with a corrugated polyvinyl
chloride (PVC) medium (Figure A-5) which serves as the
substrate for microbial attachment. With the PVC media in
place, each cell can hold approximately 150 gallons. Air is
injected at the base of each reactor cell using a sparger tube
Nutrient
Addition
Stirrer
Fine
Particle
Slurry
from
Soil
Washer
Sample Points
Fine Particle Slurry
Air
Feed
Pump
Compressor
Figure A-2. Slurry Bio-Reactor Process Flow Diagram.
32
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Influent Pump
Nutrients
Heat Exchanger
\
Effluent Pump r- Table
v /
O
Caustic
Heater ^
Blower
Temper Tank
Reactor
Control Panels
Figure.A-3. BioTrol, Inc. Mobile Aqueous Treatment System.
To Atmosphere
[ Contaminated
Water from
I Soil Washer
X^ _ .. >
Nutrition Addition
and
pH Adjustment
[ Recycle to [
I Soil Washer \
To Carbon Filter
and POTW
(End of Test Only)
I
Aqueous
Treatment System
Figure A-4. Flow Diagram of BioTrol Aqueous Treatment System (BATS) with Sample Points.
33
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Blocks
Cross-stacked
Figure A-5. Corrugated Polyvlnyl Chloride Media.
system mounted beneath the packing support grid and a
positive displacement blower. The wastewater flows upward
from the base of each cell and contacts the fixed-film mi-
crobes. As the plug-flow stream reaches the top of a cell, the
water spills into an overflow weir. The weir directs the flow to
the base of the next cell for further treatment. The process is
repeated through cells two and three in the reactor.
The initial bacterial population, derived from the local
soil, has some resistance to the toxicity of the local contami:
nants and has developed a population distribution which
favors the destruction of those chemicals. After this bacterial
source has been allowed to acclimate on the matrix, an inocu-
lum of a Flavobacterium specific to the target chemical,
pentachlorophenol in this case, is added and further acclima-
tion is allowed to occur using the subject wastewater in a total
recycle mode. The system is then ready for once-through
treatment of process water. Since the BATS had only recently
completed operation with penta-contaminated groundwater at
the site, much of this acclimation was already completed and
only two residence times with process water from the Soil
Washer was necessary to complete the acclimation process.
After passage through the three cells of the BATS, the
stream then passes through a non-contact heat exchanger
where heat is transferred to the incoming water to minimize
the operation of the heater in maintaining an influent water
temperature of about 21ฐC (70ฐF). The treated water leaves the
BATS trailer and is pumped to a holding tank.
The effluent from the BATS reactor can contain up to 30
mg/L of sloughed biomass during normal operation. Over a
period of time (approx. 6 months), a biomass film may form
inside the heat exchanger n<;cessitating backflushing. While
the influent fed to the BATS during the demonstration test
contained 500-800 ppm of solids, these were primarily fine
clay particles and no fouling problems were observed during
the test
Air emissions from the El ATS cells are vented outside the
trailer. For the demonstration, the lid over the reactor was
fitted with flexible tubing so that the offgases could be passed
through a carbon adsorption canister. After passing through
the carbon canister, air emissions are discharged to the atmo-
sphere.
34
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[NOTE: This Appendix was provided by the vendor.]
Appendix B
BioTroIฎ Soil Washing System
Technology Description
The BioTroIฎ Soil Washing System (U.S. Patent No.
4,923,125) is a water-based volume reduction process for
treating excavated soil. Soil washing is based on the premise
that: (1) contaminants tend to be concentrated in the fine size
fraction of soil (silt, clay, and soil organic matter), and (2)
contaminants associated with the coarse soil fraction (sand
and gravel) are primarily surficial. The objective of the pro-
cess is to reduce the volume of material while producing a
washed soil product which meets appropriate clean-up crite-
ria.
Following debris removal, soil is mixed with water and
subjected to various unit operations common to the mineral
processing industry. Process steps may include mixing
trommels, pug mills, vibrating screens, froth flotation cells,
attrition scrubbing machines, hydrocyclones, screw classifi-
ers, and various dewatering operations.
Intensive scrubbing is the technology at the core of the
process. For the gravel fraction, scrubbing is accomplished
with a mixing trommel, pug mill, or ball mill. For the sand
fraction, a multi-stage, counter-current, attrition scrubbing
circuit with inter-stage classification is used. This scrubbing
action disintegrates soil aggregates, freeing contaminated fine
particles form the sand and gravel fraction. In addition, surficial
contamination is removed from the coarse fraction by the
abrasive scouring action of the particles themselves. Contami-
nants may also be dissolved as dictated by solubility charac-
teristics or partition coefficients. To improve the efficiency of
soil washing, the process may include the use of surfactants,
detergents, chelating agents, pH adjustment, or heat. In many
cases, however, water alone is sufficient to achieve the de-
sired level of contaminant removal while minimizing cost
These three mechanisms: (1) dispersion and separation of
contaminated fine particles, (2) scouring of coarse particle
surfaces, and (3) dissolution of contaminants each operate to
varying degrees, depending upon the characteristics of the soil
and contaminants).
A significant reduction in the volume of material which
requires additional treatment or disposal is accomplished by
separating the washed, coarse soil components from the pro-
cess water and contaminated fine particles. A simplified
flowsheet of the system is shown in Figure B-l.
The contaminated residual products can be treated by
other methods. Process water is normally recycled after bio-
logical or physical treatment Options for the contaminated
fines can include off-site disposal, incineration, stabilization,
or biological treatment.
Applicability
Soil washing systems can be tailored to remove both
organic and inorganic contaminants. Research by the U.S.
Department of Energy and U.S. EPA has also shown this
technology to be directly applicable to radiologically con-
taminated soil.
For cases where the contaminants are associated princi-
pally with the fine size fraction, the amount of silt and clay,
i.e., the weight of soil passing a 74 microns (No. 200) sieve,
should not normally exceed 25 to 35 percent in order to
achieve an economic volume reduction. The fraction of silt
and clay in the soil may not be a factor when dissolution of
contaminants is the primary mechanism, i.e., the leaching of
metals or soluble organics.
Performance
BioTroI has conducted laboratory-scale testing with soil
samples from numerous contaminated sites. In general, or-
ganic contaminant levels in the washed soil are generally 90 to
99 percent lower than in the feed soil. Removal efficiencies
are dependent upon the contaminant, the initial contaminant
level, and the soil matrix. Typical testing results are provided
in Table B-l. (The objective of tests shown below was to
maximize organic contaminant removal. Although removal
efficiencies for metals were somewhat lower, the levels
achieved met customer requirements. If required, hydrometal-
lurgical techniques can be used to significantly improve met-
als removal.)
Laboratory Testing Services
Because each site is unique with respect to soil and
contaminant characteristics, it is necessary to conduct prelimi-
nary engineering studies (treatability testing) on representa-
tive soil samples. These studies are conducted at BioTrol's
Chaska, Minnesota laboratory, and may include, but are not
limited to:
Sample preparation;
35
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Make-up Water
Figure B-1. Simplified Flowsheet - BioTrolฎ Soil Washing System.
Table B-1. Results of Laboratory-Scale Testing - BioTroP Soil Washing System
Options:
1: Off-site Disposal
2: Incineration
3. Stabilization
4. Biodegradation
Site
Description
Wood Preserving
(California)
Wood Preserving
(Florida)
Wood Preserving
(North Carolina)
Chemical Plant
(Michigan)
Wire Drawing
(Now Jersey)
Contaminant
Total PAHs (1)
Arsenic
Chromium
Copper
Zinc
Pentachlorophenol
Pentachlorophenol
Total PAHs (1)
Carcinogenic
PAHs (1)
Arsenic
Chromium
Diohlorobenzidine
Benzidine
Azobenzene
TPH(2)
VOC(3)
Copper
Nickel
Silver
Before
(mg/kg)
4800
89
63
29
345
380
610
100
11
289
195
770
1000
2400
4700
2.0
330
110
25
After
(mg/kg)
230
27
23
13
108
4.0
25
5.1
1.6
64
51
13
6.0
7.0
350
0.01
100
60
4.0
Reduction
(percent)
95
70
63
55
69
99
96
95
85
78
74
98
99
>99
93
>99
70
45
84
Washed
Soil Weight
(percent)
83
90
80
90
85
80
Town Gas
(Quebec)
Pesticide
Formulation
(Colorado)
Total PAHs(1)
Chlordane
Aldrin
4,4-DDT
Diedrin
230
55
47
25
46
11
4.7
7.5
5.0
7.0
95
91
84
80
85
83
80
Notes: (1) Polynuclear aromatic hydrocarbons
(2) Total petroleum hydrocarbons
(3) Volatile organic compounds
36
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Sample characterization;
- Chemical analysis
- Sieve analysis with chemical analysis of size
fractions
. - Mineralogy
Leaching studies (to determine partition coefficients);
Soil washing tests;
Dewatering tests (contaminated fines);
Treatment tests on contaminated process water and
fines (in-house biodegradation or carbon treatment
tests if applicable, or alternatively, other third party
testing).
The preliminary engineering study can determine:
The ability of soil washing to physically process and
effectively treat the contaminated soil of interest;
The flowsheet required to achieve the desired separa-
tions;
Projected operating conditions for full-scale treat-
ment;
Estimated treatment costs for full-scale treatment
with an accuracy of -30/+50 percent, based on a
known volume of soil at a given treatment rate;
Treatment options for the contaminated process wa-
ter and fines.
On-site Demonstration Testing
BioTrol is equipped to conduct on-site demonstration
testing using a pilot-scale soil washing system. The purpose of
on-site testing is to confirm results obtained in the preliminary
engineering study (treatability test) by using a continuous,
pilot-scale system operating under actual site conditions. The
demonstration can provide assurance to the customer and the
appropriate regulatory agencies that the technology can achieve
the treatment levels required. In addition, the pilot-scale tests
can determine optimum system operating parameters to serve
as the basis for more accurate full-scale design specifications.
The pilot system consists of the following components:
Trailer-mounted soil washing system with a nominal
treatment capacity of 500 to 1,000 pounds per hour;
Up to 4 process water storage tanks, each with a
nominal capacity of 8,000 gallons;
Water treatment system (physical or biological);
Mobile office/laboratory.
A demonstration typically lasts 1 to 3 weeks in addition
' to the time required for mobilization and feed preparation.
During the demonstration, a generalized test program is em-
ployed which focuses on several key operating parameters
and their effect on system performance. Parameters can in-
clude system configuration, soil feed rate, water addition rate,
type and addition rate of chemical additives (if required), and
dewatering conditions. During steady-state operation, key
process streams are sampled at fixed intervals and composited
prior to chemical analysis. An accurate mass balance for the
system can be determined by collecting all exiting streams in
drums and measuring net drum weights over set time inter-
vals.
Full Scale Soil Washing Systems
BioTrol engineers can 'design and construct full-scale soil
washing systems for the remediation of a wide variety of soil
and contaminant conditions. Based on the results of a prelimi-
nary engineering study or if available, pilot-scale test results,
a soil washing flowsheet will be engineered to achieve the
necessary separations for a given contaminated soil. BioTrol
uses a modular design approach to easily accomplish this task
while minimizing engineering and construction costs.
The volume of contaminated soil will usually determine
the treatment capacity of a system. For example, remediation
of sites in the range of 5,000 to 100,000 cubic yards could be
accomplished in less than one year with a 20 ton per hour
system. For extremely large sites, or for a central facility,
permanent or semi-permanent systems could be designed with
treatment capacities in the range of 100 to 200 tons per hour.
Depending upon customer needs, systems can be leased
or purchased. BioTrol can provide technical and supervisory
staff, as well as operating and maintenance personnel. Alter-
natively, technical assistance and training could be provided
by BioTrol under terms of a service contract.
A 20 ton per hour mobile system can be assembled on 6
semi-trailers. A typical layout of this mobile system is shown
in Figure B-2. Approximately 0.3 to 0.5 acres is required for
the complete system, including feed hopper with earthen
approach ramp, various conveyers with associated product
piles, process water storage tank(s), water treatment system,
and field office.
Advantages
The BioTrolฎ Soil Washing System makes use of a
patented intensive scrubbing technology, unlike other ap-
proaches which are based almost entirely upon simple leach-
ing. Use of this intensive scrubbing process is the most
effective approach to soil washing.
In addition, BioTrol utilizes a process development ap-
proach for each site. This, together with modular construction
design, provides the most cost-effective method of applying
soil washing to a contaminated site. Pre-engineered modules
are simply arranged in the optimal configuration for the
unique soil and contaminant conditions, avoiding unnecessary
design and construction costs.
37
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Washed Oversize
Pile
Pug Mill/screen
Trailer
Froth Flotation
Trailer
Attrition/Cyclone
Trailer
Washed Soil
Dewatering Trailer
Washed Soil
Pile
Contaminated Fines
Dewatering Trailer
Field Office
Motor Control Center
Control Room Trailer
Water Treatment Skids
100 feet
Dewatered Fines
Pile
Process Water
Storage Tank
150 feet
Rgure B-2. Typical Plan View of a Mobile 20 Ton per Hour Soil Washing System.
BioTrol's biological treatment technologies can be
coupled, where applicable, with soil washing for treatment of
the residual products (process water, contaminated fines, and
debris), minimizing overall remediation costs.
Costs
Estimated treatment costs for a mobile, commercial-scale,
20 ton per hour soil washing system are shown graphically in
Figure B-3 as a function of tons processed. Costs include
capital recovery (charged as an equipment leasing rate) and
120
100
80
60
40
20
Cost Per Ton, $
. Total Cost (Treatment + Mobilization)
\
Treatment Cost
Mobilization Cost
10 20 30 40 50
Tons Processed (Thousands)
60
Figure B-3. Estimated Treatment Cost (typical) for a 20 Ton Per
Hour Mobile Soil Washing System.
water treatment; not included are costs for excavation, debris
removal, chemical additives:, and treatment or disposal of
residuals generated during tnsatment.
Total cost per ton is the sum of the mobilization and
treatment cost components. The estimated treatment cost of
roughly $60 per ton varies only slightly with tons processed.
Mobilization cost per ton has the most impact at relatively
small soil volumes.
For illustration, from Figure B-3, the estimated soil
washing cost for 20,000 tons of soil would be approximately
$71 per ton or $1.42 million,, Costs for treatment or disposal
of the residuals generated during soil washing must also be
calculated to estimate total remediation costs. For example,
soil washing of 20,000 tons of soil with characteristics similar
to that of the MacGillis and Gibbs SITE project would
generate 1,900 tons of woody debris and 1,300 tons of fines,
both requiring additional treatment. Using incineration at
$200 per ton for the woody debris and slurry-phase biodegra-
dation for the fines at $100 per ton, treatment of residuals
would cost an additional $510,000 or $25.50 per ton based on
20,000 tons. Total solid treatment costs, including treatment
of residuals, is therefore estimated at $96.50 per ton or $1.93
million.
Soil washing unit costs will be significantly lower for
systems with larger throughput capacities or for fixed central
facilities. In these cases, total soil washing costs could be in
the range of $25 to $50 per ton.
38
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Appendix C
Site Demonstration Results
Introduction
The goal of this demonstration project was to study the
effectiveness of the BioTrol SWS in removing penta and
PAHs from contaminated soil at a wood treating site. The
MacGillis and Gibbs site in New Brighton, MN was selected
on the basis of the Remedial Investigation/Feasibility Study
(RI/FS) and the site's inclusion on the National Priorities List
in 1984 (Figure C-l).
The MacGillis and Gibbs site has been used for wood
treatment since the early 1920s. Creosote was the preservative
until the mid-1950's when a shift was made to pentachloro-
phenol in a light oil. Impregnation was carried out in open
troughs, resulting in significant spills and drippage. In addi-
tion, the pentachlorophenol/oil mixture occasionally was used
for weed control throughout the site. In the 1970's, pentachlo-
rophenol was replaced by the newer chromated copper arsen-
ate process and enclosed pressure kettles were substituted for
the open troughs, thereby eliminating many of the sources of
contamination.
Soil Washer Performance
Input and Output Flow Rate Stability
The planned feed soil (FS) rate was approximately 275
kg/hr (610 Ib/hr) on an as-is weight basis. The Soil Washer
ran the first 28 hours of the low penta contaminated test at 250
to 300 kg/hr (550 - 660 Ib/hr). Starting at hour 28, clogging
caused by soil compacted at the base of the feed hopper
impeded the transfer of soil to the feed conveyer. Efforts to
eliminate the problem were only partially successful. This
resulted in a sharp decline in the feed soil rate to about 125 kg/
hr (280 Ib/hr), or 45% of the planned rate (Figure C-2).
The washed soil (WS) output rate appears to be very
responsive to fluctuations in the feed soil rate, and is slightly
higher than the feed soil rate, probably because the two
streams are of comparable magnitude and the retention time
within the system does not produce a significant response lag.
The output rate exceeds the feed soil input rate because of
water uptake during the soil washing process.
The minor solids streams coarse oversize (CO), fine
oversize (FO), and fine particle cake (FPC) also reflect
variations in the feed soil rate. However, the effect is less
obvious for these streams because of their small volume (less
than 75 kg/hr or 160 Ib/hr).
Municipal water (MW) was the primary aqueous input
stream, averaging 20 liters/min (5.3 gpm), while the thickener
stream (polymer in water) contributed a steady but minor flow
of 2.7 liters/min (0.7 gpm). After a few initial adjustments
through hour 10, the municipal water flow rate stabilized
between 18 and 20 liters/min (4.8 and 5.3 gpm). The flow rate
eventually was lowered to approximately 14 liters/min (3.7
gpm) in response to the decrease in feed soil input rate. Figure
C-3 compares the rates of the Soil Washer aqueous input and
the output streams during the test with the low penta soil.
The combined dewatering effluent (CDE) is sensitive to
fluctuations in the municipal water input rate and is approxi-
mately equal to the municipal water flow rate when process
water is not recycled. The sensitivity again demonstrates that
the retention time within the Soil Washer does not create a
significant response lag. The combined dewatering effluent
flow rate is equivalent to the municipal water flow rate
because the net water consumption in the Soil Washer by the
four solids-bearing output streams is approximately equal to
the flow rate from the thickener.
In the second soil washer test, using the high penta soil,
the feed soil rate stabilized between 140 and 150 kg/hr (310 -
330 Ib/hr) for the first 40 hours, until mechanical problems
with the feed system forced the Soil Washer to be operated at
less than 120 kg/hr (260 Ib/hr). After the scheduled break (in
sampling but not operation) to deliver fine particle slurry to
the Slurry Bio-Reactor (hours 50 to 80), a vibrating device
was attached to the outside of the feed hopper in an attempt to
correct the soil compaction problem. The vibrator was suc-
cessful in producing a 50 kg/hr (110 Ib/hr) jump in the feed
soil rate to approximately 200 kg/hr (440 Ib/hr) and the unit
operated at this level for 30 more hours. For the remainder of
the test, intermittent mechanical failures throughout the Soil
Washer equipment caused both instability and a drop in the
feed soil rate.
The washed soil output rate closely reflected changes in
the feed soil rate, as during the test with the low penta soil.
However, the difference between the two flow rates was
greater, suggesting that the washed soil was generally wetter
during this test, which was confirmed by moisture determina-
tions. The other, smaller solids streams also behaved as in the
test with the low penta soil. Figure C-4 summarizes the rates
of the input and output solids streams during the high penta
soil washer test.
39
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5th Street NW
Bell Lumber
&Pole
Co. Road E-2
SITE
Demonstration
Area
0 200 400
Scale in Feet
1st Street NW I
Figure C-1. Operations at the MacGlllis & Glbbs Site.
10 20 30 40
Elapsed Time (Hours)
50
60
FLOC
10 20 30 40
Elapsed Time (Hours)
50
60
Figure C-2. Solid Stream Flows - Low Penta Soil Washer Test. Figure C-3. Aqueous Stream Plates - Low Penta SW Test.
40
-------
350
300
250
200
150
100
50
0
ฐ lo 2ฐ 30 4ฐ 50 6ฐ 70 8ฐ 90 100lio12013014ฐ150
Elapsed Time (Hours)
Figure C-4. Solid Stream Flows - High Penta Soil Washer Test.
E
fe
s.
10 -
5 -
0 20 40 60 80 100 120 140
10 30 50 70 90 110 130 150
Elapsed Time (Hours)
Figure C-5. Aqueous Streams - High Penta SW Test.
Water recycled from the BATS (i.e., BATS treated water)
was the primary aqueous input stream during the test with the
high penta soil, averaging 11 liters/min (2.9 gpm). The two
other aqueous input streams, municipal water and thickener,
provided 0.6 liters/min (0.2 gpm) and 2 liters/min (0.5 gpm),
respectively. The BATS treated water flow rate was never
stabilized during the test. The flow rate started off at about 14
liters/min (3.7 gpm) and gradually decreased to 7 liters/min
(1.9 gpm). Municipal water supplied 1 to 3 liters/min (0.3 to
0.8 gpm) during the first 90 hours of operation, after which it
was used only intermittently. The thickener stream was, once
again, constant throughout the test. Figure C-5 illustrates the
rates of aqueous inputs and outputs during the test with the
high penta soil.
The conclusions drawn from examination of the gross
input and output flow rates are:
1. The ability to operate with stability is critical. A full-
scale operation can conceivably process several hun-
dred tons of soil per day. The design, schedule, and
cost of a remediation project hinges on a reliable
throughput.
2. The primary cause of instability with BioTrol's Soil
Washer was the feed delivery system. BioTrol feels
that this problem is correctable.
Feed and Washed Soil Flow Rate Effects on
Contaminant Removal
The sharp decline in the feed soil and washed soil rates
during the test with the low penta soil raises the question,
"How does flow rate affect contaminant removal?" Data
summarized in Figure C-6 for feed soil and washed soil penta
concentrations in these fractions, respectively, indicate that
260
240
220
~ 200
If 180
? 160
IT 140
O 120
m
100
80
60
40
20
0
&
FS
10 20 30 40
Elapsed Time (Hours)
50
60
Figure C-6. Penta Concentration - Washed and Feed Soil.
Low Penta Soil Washer Test.
1. penta concentration in the washed soil was not af-
fected by the steep (55%) drop in feed and washed
soil flow rates; and
2. penta concentration in the washed soil appears to
reach a baseline of between 10 and 20 mg/kg while
penta concentration in the feed soil ranged from 80
to 160 mg/kg.
During the Soil Washer test with the high penta soil, the
Soil Washer operated under three distinct feed soil rate sce-
narios: a stable 150 kg/hr (330 Ib/hr), a stable 200 kg/hr (440
Ib/hr), and sporadic fluctuations between 150 and 200 kg/hr.
Once again, the washed soil rate reflected changes in the feed
41
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soil input rate, just as it did during the low penta SW test.
Analysis of the data (Figure C-7) indicates that:
1. penta concentration in the washed soil was not af-
fected by either a stable increase or sporadic fluctua-
tions in feed and washed soil flow rates; and
2. penta concentration in the washed soil appears to
reach a baseline of 50 to 100 mg/kg for feed soil
containing between 300 and 1100 mg/kg.
The concentrations of PAHs in the washed soil were
similarly unaffected by variable soil flow rates during both the
low penta and the high penta Soil Washer tests.
F S
WS
ฐ 10203040506070809010011012013014ฐ150
Elapsed Time (Hours)
Figure C-7. Penta Concentration - Washed and Feed Soil.
High Penta Soil Washer Test.
Removal efficiency for the Soil Washer is measured by
comparing the concentration of contaminant in the feed soil to
that in the washed soil and is defined by the following
equation:
Removal Efficiency=100 x (1 - concentration in washed soiD
concentration in feed soil
The penta removal efficiency for the low penta Soil
Washer test was 89%, based on weighted average concentra-
tions in the feed and washed soil. In the test with the high
penta soil, the penta removal was 87%. The mean PAH
removal efficiency for the low penta test was 83%. In the high
penta test, the mean removal efficiency for PAHs was 88%.
The penta and PAH removal efficiencies were relatively
unaffected by the variations in feed soil rates. There was,
however, some indication that the extraction procedure used
in the analytical procedure for pentachlorophenol and other
semi-volatiles (sonication, Method 3550) was incomplete with
the feed soils due to inaccessibility. While this was not
verified, it would have led to underestimation of the penta
concentrations in the feed soil and this, in turn, would have
led to low values for removal efficiencies. The poor mass
balance for penta would support this argument.
Higher removal efficiencies may be achievable in the
Soil Washer by:
1. increasing the amount of unit energy (i.e., energy per
pound of soil washed) in the attrition/scrubbing pro-
cess to liberate more contaminant; and
2. using a water additive to enhance the transfer of
contaminant from the washed soil to the aqueous
phase.
Fate of Contaminants
Data show that 83% of the output solids from the Soil
Washer leave the system as washed soil in both tests. It is
presumed that washed soil is returned to the site with no
further treatment, although this would require agency ap-
proval. If the Slurry Bio-Reactor is used to treat the fine
particles (7% of output solids) leaving the system, then the
total amount of solids requiring treatment by other technolo-
gies is reduced to under 10%. This represents a volume
reduction of 90%. Table C-l summarizes the fate of total
mass, total solids, penta, and carcinogenic PAHs in the Soil
Washer. These data can be interpreted to mean:
1. Water soluble contaminants such as penta accumu-
late largely in the combined dewatering effluent and
the fine particle caike. Both of these output streams
can be treated biologically (BATS and SBR).
2. Water insoluble compounds such as PAHs gather
mostly in the fine particle cake, with much less in the
process water.
3. A low percentage (about 10%) of the mass of pollut-
ants entering the Soil Washer remains on the washed
soil. However, since the washed soil has a large
solids content, the resulting pollutant concentration
is low.
4. For dioxins, the combined or Total CDD/CDFs, 63%
and 71% of the output mass is found in the fine
particle cake in the low and the high penta soil tests,
respectively. Only 12% and 5% of the Total CDD/
CDFs output mass remains in the corresponding
washed soils (Table C-2).
Slurry Bio-Reactor Performance
The volumetric flow rate through the SBR was quite
constant at about 0.024 L/mln (0.38 gph). Since the total SBR
volume was 180 liters, this corresponded to an average reten-
tion time of about 5 days.
Penta concentrations in the solid phase of the influent
were approximately two orders of magnitude higher than for
the liquid phase. It was felt that the main reason for this was
that the penta solubility in water is limited to about 80 ppm.
Penta concentrations in the Kquid phase of the influent
42
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Table C-1. Soil Washer Input and Output Streams Low and High Penta Soil Washer Tests
Input Streams
Feed Soil (s)
Municipal Water (aq)
Thickener (aq)
Output Streams
Washed Soil (s)
. Coarse Oversize (s)
Fine Particle Cake (s)
Fine Oversize (s)
Combined Dewatering
Effluent (aq)
High Penta SW Test
Input Streams
Feed Soil (s)
Municipal Water (aq)
Thickener (aq)
ATS Treated Water (aq)
Output Streams
Washed Soil (s)
Coarse Oversize (s)
Fine Particle Cake (s)
Fine Oversize (s)
Combined Dewatering
Effluent (aq)
Rate
220 kg/hr
1200 kg/hr
180 kg/hr
260 kg/hr
32 kg/hr
48 kg/hr
13 kg/hr
1 100 kg/hr
Total
Rate
160 kg/hr
36 kg/hr
120 kg/hr
660 kg/hr
210 kg/hr
28 kg/hr
36 kg/hr
9.1 kg/hr
720 kg/hr
%of
Input
13.8
75.0
11.3
%of
Output
17.9
2.2
3.3
0.9
75.7
Mass
%of
Input
16.4
3.7
12.3
67.6
%of
Output
20.9
2.8
3.6
0.9
71.8
Cone.
89%
260 mg/L
N/A
Cone.
73%
69%
30%
8%
650 mg/L
%of
Input
99.9
0.1
N/A
%of
Output
83.1
9.7
6.4
0.5
0.3
Total Solids
Cone.
84%
310 mg/L
N/A
480 mg/L
Cone.
51%
35%
16%
69%
740 mg/L
%of
Input
99.9
0.0
N/A
0.2
%of
Output
8.3
7.3
0.8
83.2
0.3
Cone.
130 mg/kg
0.0 mg/L
0.0 mg/L
Cone.
14 mg/kg
1 70 mg/kg
270 mg/kg
96 mg/kg
14 mg/L
%of
Input
100.0
0.1
0.0
%of
Output
9.4
14.1
33.5
3.2
39.8
Pentachlorophenol
Cone.
680 mg/kg
0.0 mg/L
0.0 mg/L
2.8 mg/L
Cone.
87 mg/kg
1 400 mg/kg
1300 mg/kg
900 mg/kg
80 mg/L
%of
Input
98.3
0.0
0.0
1.7
%of
Output
10.7
23.1
27.5
4.8
33.9
Cone.
247 mg/kg
0.0 mg/L
Omg/L
Cone.
42 mg/kg
309 mg/kg
779 mg/kg
208 mg/kg
0.5 mg/L
Total
Cone.
247 mg/kg
0 mg/L
0 mg/L
0.2 mg/L
Cone.
42 mg/kg
309 mg/kg
779 mg/kg
208 mg/kg
0.5 mg/L
%of
Input
100.0
0.0
0.0
%of
Output
17.8
16.1
60.8
4.4
0.9
PAH's
%of
Input
99.7
0.0
0,0
0.3
%of
Output
18.5
18.1
58.7
4.0
0.8
Cone.
204 mg/kg
Omg/L
0 mg/L
Cone.
3.9 mg/kg
18 mg/kg
62 mg/kg
123 mg/kg
0.04 mg/L
%of
Input
100.0
0.0
0.0
%of
Output
16.3
9.3
47.9
25.8
0.7
Carcinogenic PAH's
Cone.
71 mg/kg
Omg/L
Omg/L
Omg/L
Cone.
8.9 mg/kg
96 mg/kg
1 79 mg/kg
86 mg/kg
0.3 mg/L
%of
Input
72.7
0.0
0.0
0.0
%of
Output
15.6
22.4
53.7
6.5
1.8
Notes: (aq) = aqueous stream; (s) = solid stream; % of input and output are on a mass basis
Table C-2. Dioxin/Furans Distribution in the Soil Washer
Stream , average rat
kg/hr
Low Penta SW Test
Feed Soil ;
Municipal Water
Thickener Stream
Input Total
Coarse Oversize
Fine Oversize '.
Fine Particle Cake
Washed Soil
Comb. Dewater Eff.
Output Total
220
1200
180
1600
32
13
48
260
1148
1501
e
cone
(ppm)
1.365
0
0
1.043
1.824
3.130
0.109
0.002
Total CDD/CDFs
mass/hr % of output
(mg) (%)
300.30
0.00
0.00
300.00
33.38
23.72
151.20
28.31
2.30
238.91
_
.
14.0
9.9
63.3
11.8
1.0
High Penta SW Test
Feed Soil 160 2.508 401.28
Municipal Water 36 0 0.00
BATS Effluent 660 0 0.00
Thickener Stream 120 0 0.00
Input Total 976 401.28
Coarse Oversize 28 2.319 64.93
Fine Oversize 9.1 1.235 11.23
Fine Particle Cake 36 6.818 245.45
Washed Soil 210 .078 16.38
Comb. Dewater Eff. 720 .0082 5.90
Output Total 1003.1 343.90
18.9
3.3
71.4
4.8
1.7
decreased over the fourteen day test period whereas solid
phase penta concentrations remained constant. Similar trends
observed for the PAHs would indicate that some biodegrada-
tion was occurring in the holding tank prior to the SBR inlet.
Based on the analytical results, the acclimation period
actually extended about 5 days more than originally antici-
pated. After this adjustment period, liquid phase penta reduc-
tions remained fairly constant at around 97% but asymptotically
increased from 65% to 92% for the solid phase. This type of
performance can probably be traced back to the contaminant
concentrations of the liquid phase being two orders of magni-
tude less than the concentration of the solid phase. This
insures that there are sufficient bacteria to consume just about
all of the contaminant in the liquid phase. Conversely, the
solid phase has such a high contaminant concentration that
bacteria must be generated, thereby extending the acclimation
period until a population large enough or aggressive enough
to consume most of the contaminant has been produced
assuming the high concentration on the solid is not inhibitory
or even toxic, as discussed earlier. Figure C-8 shows the
variation in overall penta removal efficiency i.e., solid and
liquid phases combined, as the test prpgressed. Had the SBR
been allowed to operate for a longer period of time, its
performance might have stabilized at a steady-state value that
43
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100
90
80
70
60
50
40
30
20
10
J_
_L
3456789
Influent Flow Test Day
Rgura C-8. Overall Penta Removal
Slurry Bio-Reactor.
would have been more indicative of the unit's capability and
BioTrol's penta removal claims of 90-95%.
After acclimation, PAH removal efficiency was at least
70% for all compounds of interest Heavy metals did not
appear to adversely affect the biodegradation process but
instead appeared to pass through the system. Very little, if
any, organic compounds were volatilized from the SBR based
on analysis of the carbon in the exhaust line adsorber.
Biotrol Aqueous Treatment System Results^
A biomass had already been established in the BATS in
the earlier demonstration using contaminated groundwater.
The field effort for that demonstration was finished on Sep-
tember 1,1989 and the BATS continued to run with contami-
nated groundwater at a low flow rate to maintain the biomass
until the start of the BioTrol Soil Washing System demonstra-
tion. On September 27,1989, the system was switched from
groundwater to SW process water and allowed to acclimate
for two residence times before sampling was initiated. The
BATS test consisted of two phases. During the first phase,
process water from the low penta concentration Soil Washer
test was treated. During the second phase, process water from
the high penta concentration Soil Washer test was treated.
Test Procedures
The BATS influent and effluent were sampled around the
clock using ISCO automatic samplers to composite six-hour
samples. The samplers automatically collected 250 ml grab
samples every 10 minutes and deposited them in a composite
container. Fourteen composite samples were collected over a
period of approximately 3.5 days in the first phase, using
process water from the low penta SW test Twenty-three
composite samples were collected over a period of approxi-
mately 6.5 days in the second phase (high penta process
water). The samples were kept on ice during compositing. The
BATS carbon canister also was sampled at the end of the test.
Four composite samples of tliie carbon canister were obtained,
each consisting of four individual grab samples of 750 ml.
Samples of the sludge in the bag filter also were planned, but
the test ended ahead of schedule and no sample of the material
in the bag filter was collected.
Field measurements were collected at various intervals
over the course of the BATS tests. Every two hours, measure-
ments of influent, effluent, and nutrient flow rates were taken
by recording the depth of liquid in the respective tank. Every
eight hours, measurements of pH and temperature were col-
lected from grab samples of influent and effluent taken at "T"
joints in the influent and effluent lines of the system. Power
readings were recorded every eight hours from a standard
domestic electric power meter. The pH adjusting chemicals,
flow rate, and the weight of the carbon in the adsorption
canister were measured using a direct-read floor scale.
Sampling and Analysis
All of the samples were analyzed for penta and full semi-
volatile priority pollutant scans. Analyses for other constitu-
ents were performed on selected samples at varying
frequencies. Included were heavy metals, total residue, total
recoverable petroleum hydrocarbons, chemical oxygen de-
mand, chloride ion, total organic halides, and polychlorinated
dibenzodioxins and dibenzofurans. The BATS carbon canis-
ter was analyzed for penta, semi-volatiles, and total residue.
System Parameters
Flow rates remained very steady for both the influent and
the effluent over the entire course of the tests. The mean
influent flow rate was 10.2 L/min (2.69 gpm) in the first test
and 10.1 L/min (2.67 gpm) in the second test. The mean
effluent flow rate was 9.94 L/min (2.63 gpm) for the first test
and 10.1 L/min (2.67 gpm) for the second test.
The heater was in use during this demonstration because
of the low ambient temperatures encountered in Minnesota in
late September. The average Influent temperatures were 16.5ฐC
for the first test and 14.6ฐC for the second test. The average
effluent temperatures were 25.2ฐC and 24.7ฐC for the two
tests, respectively. Some increase in temperature from influ-
ent to effluent was expected due to biodegradation in the
BATS.
The influent pH range, after adjustment, was 7.03 to 7.5
in the first test and 6.6 to 9.07 in the second test. The effluent
pH range was -7.21 to 7.83 ifbr the first test and 6.64 to 9.19
during the second test The vendor had specified a pH of
approximately 7.3 as the ideal pH for the system and measure-
ments indicate that this was achievable through the on-line pH
adjustment system. The pH of the SW process water, before
pH adjustment, varied over the course of the test, but was in
the range of 6.64-8.03 standard units, which would be suitable
for the BATS.
Total recoverable petroleum hydrocarbons were analyzed
as a measure of the oil (which was used as a carrier for penta
during wood treating operations at MacGillis & Gibbs) in the
soil and subsequently in the process water leaving the soil
44
-------
washer and entering the ATS. The analyses showed total
recoverable petroleum hydrocarbons in the low ppm range in
both the influent to and the effluent from the BATS. If
significant oil were present, an oil/water separator would need
to be added as a pretreatment step prior to the BATS; the
system is designed to accommodate this modification as a
pretreatment step.
Chemical oxygen demand was included as a measure of
the total potential oxygen demand (both biochemical and
chemical) of the samples, which may include substances other
than those being analyzed. The observed COD measurements
indicated that chemical oxidation was occurring in the BATS,
but a significant decrease from influent to effluent was not
apparent This could be attributed to other organic constitu-
ents which were not included in analyses and which were not
degraded biologically or removed by other mechanisms in the
BATS.
Pentachlorophenol Removal
During the first test, the weighted influent concentration
of penta was 15 ppm and the weighted effluent concentration
was 1.3 ppm. This corresponds to a 91% removal for penta.
During the second test, using the water from the high penta
S W test, the weighted influent concentration of penta was 44
ppm and the weighted effluent concentration was 3 ppm. This
corresponds to a 93% removal of penta: during the second test.
The data have been plotted in Figure C-9 and C-10 for each
test, respectively. After an initial period of biomass acclima-
tion, effluent concentrations held fairly steady in the low ppm
range even when influent concentrations varied significantly.
The data confirm that the BioTrol Aqueous Treatment System
is effective at removing pentachlorophenol from the SW
process water (CDE), although it should be noted that there
also was a significant decrease in the penta concentration in
the CDE before it was introduced to the BATS, due to
biodegradation in the storage tank or sedimentation of penta-
rich solids. '.
Based on the mass of penta introduced to the system over
each test, and assuming that all penta is lost by biological
degradation, mass removals of >90% are achievable (Table C-
3).
Table C-3. Mass Removal of Pentachlorophenol
Test
Total Penta
in (gm) out (gm)
Removal
Test One - Low Penta 740 60 91.9
Test Two - High Penta 3700 220 94.1
Mineralization of Penta
Samples were analyzed for chloride ion and total organic
halides to ascertain whether the penta was being mineralized
or if it was only being partially degraded to other organic
compounds. Table C-4 summarizes the changes in chloride
and total organic halide data and compares the results with
calculated values based on penta removal. For the first four
samples, chloride concentrations increase from influent to
effluent as expected, but for the last two samples chloride
concentrations decrease and there is no adequate explanation
for this.
A decrease in total organic halides would indicate that the
chloride leaving the system was inorganic. Looking at the data
for total organic halides (also shown in Table C-4), only three
of the samples show a decrease in concentration of TOX
between influent and effluent; the other three samples show
an increase.
Table C-4. Compel
Penta R
Penta
SAMPLE Change
(mg/L)
04-2
04-4
05-2
05-4
06-2
06-4
-18.1
-74.7
-76.8
-34.8
-37.1
-41.3
ison of Chloride and TOX Changes with
emoval
Increase In Decrease In
Cl (fd)
(mg/L)
+ 9.5
+29.4
+32.8
+32.5
-16.0
-47.6
Cl (calc)
(mg/L)
+12.05
+49.75
+51.15
+23.18
+24.71
+27.51
TOX(fd)
(mg/L)
+ 1.1
-4.0
-8.0
-7.2
+ 4.0
+ 6.6
TOX (calc)
(mg/L)
+ 12.1
+ 49.8
+ 51.2
+ 23.2
+ 24.7
+ 27.5
fd = found
calc = calculated from change in penta; 0.67 mg Cl (or TOX) per mg
of penta decrease.
Cone, of Pentachlorophenol x 1000 (u.g/L)
10
20 30 49 50 60 70
Time from Beginning of the Test (hrs)
Figure C-9. BATS-Penta Concentration in Low Penta Test.
80 90
Cone, of Pentachlorophenol x 1000 (ng/L)
80--
70-
60--
50-
40--
30--
20--
Biomass
Acclimation
Period
10--
90 100 110 120 130 140 150 160 170 180 190 200 210 220 230240
Time from Beginning of the Test (hrs)
Figure C-10. BATS-Penta Concentration in High Penta Test.
45
-------
Thus, no conclusions can be drawn from this data as to
whether the chloride leaving the system is inorganic. The
companion study, which concentrated on the BATS, and other
published information do strongly indicate that mineralization
is the predominant path for penta removal.
Analyses for total solids (suspended and dissolved) were
performed on the influent and effluent samples of the BATS.
Concentrations of solids in the 500 ppm range were encoun-
tered both in the influents and effluents during both tests.
Results of a material inventory showed only an 8.5% loss of
solids during the low penta test and a 4% gain in solids during
the high penta test The material inventory results confirm that
the penta was not removed by entrapment of solids within the
reactor. There was a slight build-up of solids during the first
test which was later released during the second test.
gests a build-up of metals in the aqueous stream as it was
recycled within the SW system. Weighted averages for the
metals in the two tests are shown in Table C-5. The presence
of metals at concentrations of up to 90 |J.g/L did not appear to
affect the biomass adversely.
Table C-5. Weighted Concentrations of Metals in BATS Tests
(MI/L)
Arsenic Chromium Copper
Low Penta test
Influent
Effluent
High Penta test
Influent
Effluent
15.9
15.7
66.0
54.3
10.6
7.9
16.2
12.3
25.3
13.0
40.4
25.5
Polynuclear Aromatic Hydrocarbon (PAH)
Removal
Concentrations of the various PAHs were lower than
anticipated in both the BATS influent and effluent During the
low penta test of the BATS, only one PAH, anthracene, was
detected with any frequency. Analyses of effluent samples for
this test yielded all non-detected values with method detection
limits ranging from 2-15 ppb dependent on the specific com-
pound. During the high penta test of the BATS, no PAH
compounds were detected with any frequency. Method detec-
tion limits ranged from 1-400 ppb.
The lack of actual data values for PAHs in both influent
and effluent to the BATS makes it impossible to assess the
removal of these chemicals across the system.
Heavy Metals
Samples were analyzed for copper, chromium and ar-
senic (CCA) to determine the fate of the metals in the BATS.
Concentrations of metals increased slightly in the influent to
the BATS over the course of the demonstration, which sug-
Results of the material inventory for metals indicates that
there was an accumulation of metals inside the reactor. In a
commercial scale system operated with full recycle of all
process water for several months, the metals could possibly
build-up to concentrations which would be toxic to the micro-
organisms. Some purging of metals from the system might
then be required and could, be accomplished by providing
treatment for metals prior to recycle of the process water. The
exact nature of metals treatment would be dependent upon the
concentrations of metals at a specific site, the length of
remediation (several months to several years), the tolerance of
the biomass for heavy metals, and regulatory standards.
The reader may be interested in the ranges of values for
all flows and species as an indication of the uniformity or
consistency of the processes, the soils, and the analytical
procedures. While weighted averages have been used in this
report to adjust for variations in flows in all processes and to
minimize the impact of short term variations on removal
efficiencies, the summary tobies provided in the Technology
Evaluation Report also present simple arithmetic averages
and standard deviations.
46
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Appendix D-l
Treatability Studies of Soil Washer System
Other than the current Demonstration under the SITE
Program, no results for pilot or large scale evaluations of the
Soil Washing System are available. Consequently, there are
no comparable data for removal efficiencies or costs based on
large sized systems. However, BioTrol has carried out several
treatability and bench scale studies. The results of those
studies are presented in this section. Subsequent sections of
this Appendix do provide extensive data on pilot and full scale
BATS installations. '
Wood Treatment Site (Penta/PAHs)
The soil at a former wood treating (creosote and penta-
chlorophenol) facility was found to be a mixture of gravel-
sized chert and clay. About 80% was larger than 10 mesh. The
-10 mesh fraction contained 2300 ppm penta. During attrition
scrubbing, the sand fraction (-10 mesh to +200 mesh) lost
about 50% of its weight to the fines (<200 mesh) fraction.
Removal of penta from the sand fraction during soil washing
was about 75%. Slurry biodegradation of the -10 mesh frac-
tion with the indigenous consortium of penta degrading bacte-
ria was characterized by a lengthy induction phase, rapid
initial remediation while the readily exchangeable penta was
degraded, and a slow residual remediation phase. During this
final phase, aqueous penta concentrations were <1 ppm. Over-
all, bioremediation was effective in degrading about 83% of
the penta in the -10 mesh soil fraction. Overall degradation for
phenanthrene, fluoranthene, and pyrene were >95%, 92%,
and 77%, respectively.
Biodegradation of the woody sample indicated that penta-
degrading organisms were present; at 5% solids the rate of
degradation was about 10 mg penta/liter of slurry/day. A final
penta concentration of about 100 ppm was achieved with the
woody soil. Slurries of the representative soil could only be
degraded after seeding with the woody soil, after which final
concentrations of about 25 ppm could be achieved.
Pesticides Formulation Site
BioTrol carried out bench scale tests on soil from an
inactive pesticide formulation facility on the National Priority
List. The primary contaminants of concern were chlordane,
aldrin, 4,4-DDT, and dieldrin at concentrations ranging from
20 ppm to about 80 ppm.
Particle size and chemical analyses determined that 15%
of the sandy/silty soil (dry weight) was finer than 200 mesh
(<75 micron) and that the pesticides were predominantly
associated with the fines. Thus, soil washing could reduce by
85% the quantity of soil that would otherwise require
remediation.
Using attrition scrubbing, inter-stage classification, and
wet gravity separation, overall pesticide removal from the
+200 mesh fraction were about 85%. Final pesticide concen-
trations in the washed +200 mesh soil were in the range of 5 to
7 ppm. Addition of two different surfactants did not enhance
removal.
Wood Treatment Site (Penta/TRPs)
Two samples of the soil at this site were evaluated, one
containing a significant portion of decaying woody material
and 603 ppm penta, and another containing 379 ppm of penta
The latter sample was considered more representative of the
site. Studies indicated that the rate of penta leaching into
water was rapid for both samples, reaching near equilibrium
conditions in about 3 hours.
Soil washing of the soil reduced the penta concentration
in the "representative" soil to 3.6 ppm or less, with approxi-
mately 90% of the feed soil recovered as washed soil with that
level. Washing of the woody soil (603 ppm penta) produced a
washed soil with 25-30 ppm penta, which would not have met
the site cleanup criteria. Experiments indicated that gravity
separation would be effective in removing wood from this
washed soil and thus reducing the penta concentration further.
Industrial Chemical Site
Two samples of soil from beneath lagoons at a chemical
production site were found to be contaminated with chlori-
nated and non-chlorinated semivolatile chemicals. One soil,
considered the "worst case," contained about 1000 ppm of
total contaminants. A process sequence was devised that
consisted of agglomeration of tar, screening to remove the tar,
soil washing to scour the surfaces of the sand, flotation to
remove residual tar from the washed soil, and recovery of
contaminated fines. The process was effective in removing
99+% of the non-chlorinated semivolatiles and about 98% of
the chlorinated semivolatile contaminants. Excluding the treat-
ment of residuals, the pile-to-pile cost for remediation was
estimated at $45/cubic yard.
47
-------
Metal Contaminated Site TRP cu MI Ag
Two samples of contaminated soil from a wire drawing So\\ 5000 330 200 25
operation were evaluated. The first sample, containing an Washed Soil 350 100 85 4
average of 30% Total Petroleum Hydrocarbons (TRPs), did
not respond adequately to efforts to remove metals by soil
washing without surfactant. The second soil sample, which An order-of-magnitude cost estimate was generated which
was considered more representative of the soil at the site, was indicated overall remediation could be carried out for $330/
treated more successfully. While particle disintegration did cubic yard, with capital cost for the system estimated at $1.5
not appear to occur during the attrition scrubbing, the washed million.
soil recovery was 80%. Contaminant concentrations v/ere
reduced as follows:
48
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Appendix D-2
BATS Treatment at a Full Scale Wood Preserving Site
Introduction
The subject of this study is a wood preserving facility
using the Boultonizing process that generates a process water
contaminated with creosote-derived phenolics, polynuclear
aromatic hydrocarbons, and aromatic compounds extracted
from the wood. The BATS unit offered an opportunity to treat
this wastewater biologically in a compact, efficient manner
with minimal operator attention.
The process water to be treated contained significant oily
material. It is treated in two stages for oil/water separation and
then cooled in a cooling tower. Water from the cooling tower,
which was previously discharged to an on-site lagoon, was
treated in the pilot study and, subsequently, in the commercial
unit. The character of the feedwater varied considerably,
depending on the type of wood treated, rainfall, and evapora-
tion rates (Table D-l).
Table D-1. Characteristics of Phenolic Process Water
constituent average range
(ppm) (ppm)
Phenols
COD
BOD
TSS
Oil/grease
PH
Temperature (F)
129
1059
752
104
28
11-327
412-1912
75-1200
22-659
8-270
6-9
80-90
Pilot Scale Studies
A pilot scale demonstration study using a 3-celled mobile
BATS unit with a 15 gpm flow capacity was carried out over
six weeks at flow rates of 2 gpm and 1 gpm. Influent and
effluent samples were collected daily as 24-hour composites
while the bioreactor cells were grab-sampled. Key analyses
were total recoverable phenolics (TRP) by Standard Method
510.B and chemical oxygen demand (COD) by the OI Corp.
method. In addition, biochemical oxygen demand (BOD), oil
and grease, and total suspended solids were also analyzed. On
three occasions during the course of the pilot demonstration,
samples were analyzed by EPA Method 610 for polynuclear
aromatic hydrocarbons (PAHs).
Based on analytical results (Figure D-l), effluent concen-
trations of phenols were almost always below 1 ppm, corre-
sponding to an average phenolics removal of >99%. Decreases
in biochemical oxygen demand (BOD) and chemical oxygen
demand (COD), while significant, were not as great, possibly
due to sloughed biomass. Variations in total suspended solids
(TSS) indicate a cyclic character to the TSS values and
suggests that solids accumulation occurs followed by solids
release. Polynuclear aromatic hydrocarbon removal was in the
range of 80+%, but elevated PAH levels for total samples
(including sloughed solids) from the middle cells suggest that
adsorption of PAHs on solids as well as biodegradation is
occurring (Figure D-2).
Commercial System Evaluation
Based on the success of the pilot scale demonstration in
removing phenolics from the aqueous wastewater, a commer-
cial (30 gpm) unit was installed in August 1988. After a two
week acclimation period (no specific bacterium was added),
the unit has been in continuous operation with the flow rate
starting at 20 gpm and then increased to the design rate of 30
gpm. The effluent is discharged to a POTW. Based on the
results for the first 5 months of operation (Table D-2), the
system has produced-effluent.with an average phenolics con-
centration below 1 ppm with minimal operator attention.
Table D-2. Wood Preserving Wastewater Treatment by BATS
Month Phenolics in Effluent (ppm)
August
September
October
November
December
5 Month Average:
0.12
0.058
0.14
0.20
1.11
0.33
Cost Data
Operating cost data were developed on the basis of opera-
tion of the commercial unit. Assuming a 30 gpm flow rate and
an influent with 1000 ppm of BOD and 200 ppm of phenols,
the operating costs were as shown in Table D-3.
Table D-3. Operating Cost for BATS Commercial Unit
Cost item $/1000 gallons
Electricity (@ $0.06/Kwhr) 0.15
Nutrients (@ $0.71/gallon) 0.14
Labor (10 hr/wk @ $15/hr) 0.49
Total 0.78
49
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Cell 1 Cell 2
Location
Effluent
Figure D-1. Total Recoverable Phenols - using BATS.
Figure D-2. PAH Removal by BATS.
Conclusions
Based on the pilot scale studies and operation of the
commercial unit for several months, the BATS is a cbst-
effective means of removing phenolics and polynuclear aro-
matic hydrocarbons from this wastewater.
The nature of the BATS system is such that it requires a
minimum of labor relative to conventional activated sludge
systems where trained personnel may be needed to assure that
optimum sludge separation and return is carried out.
50
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Appendix D-3
BATS TVeatment at a Tape Manufacturer
California
Introduction
A tape manufacturing facility in California produces about
15,000 gpd of solvent-contaminated process water. Contribut-
ing to a high COD are toluene, xylene, methyl ethyl ketone,
tetrahydrofuran, and cyclohexanone. Currently, the plant uses
activated carbon pretreatment prior to discharge to the POTW.
Biological treatment was considered as an alternate, less
costly treatment.
A bench scale continuous evaluation of biological treat-
ment using the BATS was carried out. Because of high
variability in wastewater loading, the goal of the investigation
was to evaluate the effectiveness of the system at various
organic loadings, in addition to the removal of specific con-
taminants.
Bench Scale Study
The bench scale continuous studies were carried out
using a 55 gallon drum of process water shipped to the
BioTrol facility. The system consisted of a 4 in. ID translucent
PVC column packed to a depth of 12 in. with 1 in. Intalox
PVC saddles to simulate the structured PVC packing used in a
commercial unit. Air was injected at the base. The column
was inoculated with activated sludge from a POTW and
acclimated over 10 days. Continuous operation was then
maintained for 1 week at each of 3 flow rates: 2, 4, and 8
liters/day, corresponding to loadings of 110, 235 and 485 Ib
COD/1000 cu ft of packing/day.
Results
Samples were removed by BioTrol and measured for the
parameters noted in Table D-4 using standard methods.
Biological treatment effectively removed 99% of the
specific components of concern with only slight fall off in
efficiency when the loading rate was increased from 110 to
235 lbs/1000 cf/day. Final effluent with residual concentra-
tions of 5 to 15 ppb were achieved at the lower loading and
somewhat higher at the higher loading.
Table D-4. BATS Removal Efficiency - Tape Process Water
parameter
Loadina:
toluene, xyiene
MEK
THF
COD
Loadina:
toluene, xylene
MEK
THF
COD
influent effluent
ppm ppm
100lb/1000cf/dav
1.3 <0.01
43.0 <0.005
5.7 0.014
3178 758
235lb/1000cf/dav
1.3 0.06
43.0 0.55
5.7 <0.05
3178 1413
removal
%
>99
>99.9
>99.7
76
95
98.7
>99.1
55
The difference between removal efficiency for specific
components and that for COD is consistent with the presence
of other, more recalcitrant constituents. (Other tests indicate
that stripping of volatile organics accounts for less than 10%
of their removal.)
Cost Data
Using the removal data developed in the bench scale
study, cost data were developed for a commercial system with
a 10 gpm capacity. On that basis, the total anticipated operat-
ing cost would be $3.51/1000 gallons of wastewater, as shown
in Table D-5.
Table D-5. Operating Cost for 10 GPM BATS System
item $71000 gal
Nutrients (liquid fertilizer) 0.32
Electricity (for pumps) 0.37
(2 Ib oxygen/hp-hr andIO gpm
effluent pump @ 50 ft head)
Labor (10 hrs/wk @ $20/hr)
Base for neutralization (NaOH)
Total
1.98
0.84
$3.51
51
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Appendix D-4
BATS Treatment of BTEX
Minnesota
Introduction
A truck stop in Minnesota experienced widespread soil
contamination by gasoline from leaking underground storage
tanks. In addition to removing the tanks and highly contami-
nated soil, it was necessary to treat soil beneath buildings and
groundwater to prevent spread of a contaminated plume.
BioTrol proposed that both goals could be achieved by
above-ground treatment of the groundwater in a BATS, fol-
lowed by reinjection of the treated water to stimulate in situ
bioremediation of the soil. Laboratory studies demonstrated
that with proper additions of nutrients and oxygen, the indig-
enous microflora were capable of destroying benzene, tolu-
ene, ethyl benzene, and xylenes (BTEX) in the soil to below
detectable levels in eight days. Since this remediation scheme
depended on initial above-ground treatment to levels suitable
for reinjection, a pilot scale evaluation of the BATS was
deemed to be necessary.
Pilot Scale BATS
A single column pilot-scale BATS was installed at a gas
station in the Minneapolis area. The reactor column was 1 foot
in diameter and filled to nine foot depth with 1 in. Intalox
PVC saddles to simulate the structured PVC packing used in
the full scale unit. The system provided 1.6 hours of residence
time.
The system was first acclimated for two weeks with no
addition of bacteria except that in the groundwater. The
reactor was then sampled daily for one week, using composite
samples of influent and effluent taken with a zero headspace
sampling device. Analyses of these samples confirmed that
>99% removal of BTEX could be achieved with an influent
ranging from 1900 to 15,000 ppb, and effluent concentrations
of <20 ppb for individual components were achieved. The
BTEX results are summarized in Table D-6.
Table D-6. BTEX Treatment with the BATS
day
1
2
3
influent
ppb
1962
4700
15300
effluent
ppb
<80
<80
<80
removal
>96
>98
>99
Full Scale BATS
On the basis of the pilot study it was concluded that the
process was very effective at removing BTEX. A two-stage
reactor was installed at the contaminated site to be used in
conjunction with a closed loop groundwater extraction sys-
tem. Modelling of shallow groundwater flow was used to
design the extraction well and infiltration gallery network.
The BATS is currently treating groundwater at a 15 gpm
flow rate. With a groundwater temperature of 50ฐ F, no heat
input has been found necessary to maintain reactivity. With
influent BTEX concentrations of approximately 4200 ppb,
consistent reductions to <80 ppb have been achieved. Meas-
urements of BTEX concentrations in the air exhaust from the
reactor established that air stripping accounts for removal of
only 5 - 10% of the removed BTEX.
Cost Data
The operating and maintenance cost of the combined in
situ and above-ground treatment is expected to average about
$9000/year. Total cost of remediation, including capital, main-
tenance and operation, but excluding groundwater monitoring
and project management fees, is approximately $ 165,000 with
a three-year anticipated project life. More detailed informa-
tion is not available at this time.
53
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Appendix D-5
Pilot Plant BATS
Minnesota
Introduction
In the fall of 1986, the feasibility of treating contaminated
groundwater at a wood preserving site in Minnesota was
evaluated in a nine-month pilot study using the BioTrol
Aqueous Treatment System. The study was funded by a grant
from the U.S. Geological Survey.
The purpose of the study was to establish the long term
effectiveness of the BATS for such wastewaters, particularly
for the removal of pentachlorophenol and, secondarily, for
polynuclear aromatic hydrocarbons. These materials are com-
monly found contaminating sites where wood preserving op-
erations using pentachlorophenol and creosote had been
practiced over previous decades. The groundwater at the site
contained 60-100 ppm of pentachlorophenol based on pre-
liminary studies.
Pilot Scale Study
A simple 30-gallon packed bed reactor was used in the
nine-month pilot study. The system was activated with indig-
enous microflora and later amended with inoculations of a
Flavobacterium specific to pentachlorophenol. The unit was
operated essentially in a continuous mode, over the length of
the study, adjusting pH and adding nutrients as necessary. Air
was continuously injected to maintain aerobic conditions.
BioTrol subsequently developed a proprietary bioreactor
design specifically suited to treatment of contaminated ground-
water with an amended, fixed film microbial system.
Results
The packed bed system effectively removed pentachloro-
phenol, polynuclear aromatic hydrocarbons, and other con-
stituents that were found to be present. The specific rate of
penta degradation was as high as 70 mg of penta/liter of
reactor volume/hour, well beyond the values normally re-
ported in the literature. In later work using the proprietary
system design, penta removal rates between 40 and 50 mg
penta/liter of reactor volume/hr were consistently achieved,
with rates as high as 65 mg/liter/hr being achieved. All penta
analyses were carried out using a HPLC method developed by
BioTrol. Extensive removal of polynuclear aromatic hydro-
carbons was also confirmed. While substantial reductions in
COD also occurred, the levels in the effluent indicate the
presence of considerable refractory material. Typical results
are summarized in Table D-7.
Table D-7. Groundwater Treatment in 30-Gal Packed Reactor
constituent
Pentachlorophenol
Acenaphthaiene
Naphthalene
Acenaphthene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Benzo(a)anthracene
Chrysene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Benzo(a)pyrene
Dibenzo(a,h)anthracene
Benzo(g,h,i)perylene
Fluorene
lndo(1 ,2,3-c,d)pyrene
well water
ppb
93,000
4,402
1,932
2,041
264
252
466
232
292
171
448
178
211
296
315
545
203
effluent
ppb
nd
nd
81
140
38
20
153
15
9
8
8
7
5
33
4
nd
nd
removal
%
-100
-100
96
93
86
92
67
94
96
95
98
96
98
89
99
-100
-100
COD (ppm)
250-300 100-150
>40
While the influent and effluent data over the nine-month
investigation did exhibit occasional elevated levels in the
effluent, these usually were attributable to mechanical fail-
ures, such as loss of aeration, loss of heat, etc. Daily tabulation
of influent and effluent data indicates that the system had
excellent recovery capability after such upsets.
No cost data is available for this small scale study.
55
U. S. GOVERNMENT PRINTING OFFICE:! 992/650-199
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