EPA/540/R-06/009
March 2006
Compost-Free Bioreactor
Treatment of Acid Rock Drainage
Leviathan Mine, California
Innovative Technology Evaluation Report
National Risk Management Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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Notice
The information in this document has been funded wholly or in part by the U.S. Environmental Protection
Agency (EPA) in partial fulfillment of Contract No. 68-C-00-181 to Tetra Tech EM, Inc. It has been subject
to the Agency's peer and administrative review, and it has been approved for publication as an EPA
document. Mention of trade names of commercial products does not constitute an endorsement or
recommendation for use.
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Foreword
The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the Nation's land,
air, and water resources. Under a mandate of national environmental laws, the Agency strives to formulate
and implement actions leading to a compatible balance between human activities and the ability of natural
systems to support and nurture life. To meet this mandate, EPA's research program is providing data and
technical support for solving environmental problems today and building a science knowledge base
necessary to manage our ecological resources wisely, understand how pollutants affect our health, and
prevent or reduce environmental risks in the future.
The National Risk Management Research Laboratory (NRMRL) is the Agency's center for investigation of
technological and management approaches for preventing and reducing risks from pollution that threaten
human health and the environment. The focus of the Laboratory's research program is on methods and their
cost-effectiveness for prevention and control of pollution to air, land, water, and subsurface resources;
protection of water quality in public water systems; remediation of contaminated sites, sediments and ground
water; prevention and control of indoor air pollution; and restoration of ecosystems. NRMRL collaborates
with both public and private sector partners to foster technologies that reduce the cost of compliance and to
anticipate emerging problems. NRMRL's research provides solutions to environmental problems by:
developing and promoting technologies that protect and improve the environment; advancing scientific and
engineering information to support regulatory and policy decisions; and providing the technical support and
information transfer to ensure implementation of environmental regulations and strategies at the national,
state, and community levels.
This publication has been produced as part of the Laboratory's strategic long-term research plan. It is
published and made available by EPA's Office of Research and Development to assist the user community
and to link researchers with their clients.
Sally C. Gutierrez, Director
National Risk Management Research Laboratory
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Abstract
As part of the Superfund Innovative Technology Evaluation (SITE) program, an evaluation of the compost-
free bioreactor treatment of acid rock drainage (ARD) from the Aspen Seep was conducted at the Leviathan
Mine Superfund site located in a remote, high altitude area of Alpine County, California. The evaluation
was performed by U.S. Environmental Protection Agency (EPA) National Risk Management Research
Laboratory (NRMRL), in cooperation with EPA Region IX, and Atlantic Richfield Company (ARCO), the
state of California, and the University of Nevada-Reno (UNR). The primary target metals of concern in the
ARD include aluminum, copper, iron, and nickel; secondary target metals include selenium and zinc.
Drs. Glenn Miller and Tim Tsukamoto of the UNR have developed a compost-free bioreactor technology in
which sulfate-reducing bacteria are nurtured to generate sulfides which scavenge dissolved metals to form
metal sulfide precipitates. Unlike compost bioreactors, this technology uses a continuous liquid carbon
source and a rock matrix rather than a compost or wood chip matrix which is consumed by bacteria and
collapses over time. The benefits include better control of biological activity and improved hydraulic
conductivity and precipitate flushing.
Evaluation of the compost-free bioreactor technology occurred between November 2003 and July 2005. The
treatment system neutralized acidity and precipitated metal sulfides from ARD at flows up to 91 liters per
minute (24 gallons per minute) on a year-round basis. Multiple sampling events were conducted during both
gravity flow and recirculation modes of operation. During each sampling event, EPA collected chemical
data from the system influent and effluent streams, documented metals removal and reduction in acidity
between the bioreactors, settling ponds, and aeration channel, and recorded operational information pertinent
to the evaluation of the treatment system. The treatment system was evaluated independently, based on
removal efficiencies for primary and secondary target metals, comparison of effluent concentrations to EPA
interim (pre-risk assessment and record of decision) discharge standards, and on the characteristics of and
disposal requirements for the resulting metals-enriched solid wastes. Removal efficiencies of individual unit
operations were also evaluated.
The compost-free bioreactor treatment system was shown to be extremely effective at neutralizing acidity
and reducing the concentrations of 4 of the 5 target metals in ARD flows at Leviathan Mine to below EPA
interim discharge standards. During the demonstration, pilot testing to determine optimal sodium hydroxide
addition resulted in exceedance of discharge standards for iron; however, after base optimization during
gravity flow operations effluent iron concentrations met discharge standards. Iron also exceeded discharge
standards during recirculation operations when base addition was stopped due to equipment failure or lack of
adequate base supply. Although the influent concentrations for the primary target metals were up to 580
fold above the EPA interim discharge standards, the treatment system was successful in reducing the
concentrations of the primary target metals in the ARD to between 1 and 43 fold below the discharge
standards. Removal efficiencies for the 5 primary target metals exceeded 85 percent; sulfate ion was
reduced by 17 percent. The metal sulfide precipitates generated by this technology were not found to be
hazardous or pose a threat to water quality and could be used as a soil amendment for site reclamation.
Based on the success of bioreactor treatment at the Leviathan Mine site, ARCO will continue to treat ARD
at the Aspen Seep. The state of California and ARCO are also evaluating the potential effectiveness,
implementability, and costs for treatment of other ARD sources at the mine site.
111
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Contents
Notice i
Foreword ii
Abstract iii
Acronyms, Abbreviations, and Symbols vii
Conversion Factors ix
Acknowledgements x
Section 1 Introduction 1
1.1 Project Background 1
1.2 The Site Demonstration Program and Reports 1
1.3 Purpose of the Innovative Technology Evaluation Report 3
1.4 Technology Description 3
1.5 Key Findings 7
1.6 Key Contacts 7
Section 2 Technology Effectiveness 10
2.1 Background 10
2.1.1 Site Description 10
2.1.2 History of Contaminant Release 12
2.1.3 Previous Actions 12
2.2 Process Description 12
2.3 Evaluation Approach 14
2.3.1 Project Objectives 14
2.3.2 Sampling Program 15
2.4 Field Evaluation Activities 16
2.4.1 Mobilization Activities 16
2.4.2 Operation and Maintenance Activities 16
2.4.3 Process Modifications 18
2.4.4 Evaluation Monitoring Activities 18
2.4.5 Demobilization Activities 19
2.4.6 Lessons Learned 19
2.5 Technology Evaluation Results 20
2.5.1 Primary Objective No.l: Evaluation of Metals Removal Efficiencies 20
2.5.2 Primary Objective No.2: Comparison of Effluent Data to Discharge Standards.. 22
2.5.3 Secondary Objectives for Evaluation of Bioreactor Treatment System Unit
Operations 23
2.5.3.1 Operating Conditions 24
2.5.3.2 Reaction Chemistry 26
2.5.3.3 Metals Removal By Unit Operation 30
2.5.3.4 Solids Separation 33
IV
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Contents (continued)
2.5.4 Evaluation of Solids Handling and Disposal 37
2.5.4.1 Waste Characterization and Handling Requirements 37
2.5.4.2 Bioreactor Treatment System Solids 37
Section 3 Technology Applications Analysis 41
3.1 Key Features 41
3.2 Applicable Wastes 42
3.3 Factors Affecting Performance 42
3.4 Technology Limitations 42
3.5 Range of Suitable Site Characteristics 43
3.6 Personnel Requirements 44
3.7 Materials Handling Requirements 44
3.8 Permit Requirements 44
3.9 Community Acceptance 45
3.10 Availability, Adaptability, and Transportability of Equipment 45
3.11 Ability to Attain ARARs 45
3.11.1 Comprehensive Environmental Response, Compensation, and Liability Act 46
3.11.2 Resource Conservation and Recovery Act 46
3.11.3 Clean Air Act 48
3.11.4 Clean Water Act 48
3.11.5 Safe Drinking Water Act 48
3.11.6 Occupational Safety and Health Act 48
3.11.7 State Requirements 49
3.12 Technology Applicability To Other Sites 49
Section 4 Economic Analysis 51
4.1 Introduction 51
4.2 Cost Summary 51
4.3 Factors Affecting Cost Elements 52
4.4 Issues and Assumptions 52
4.5 Cost Elements 52
4.5.1 Site Preparation 53
4.5.2 Permitting and Regulatory Requirements 53
4.5.3 Capital and Equipment 53
4.5.4 System Startup and Acclimation Costs 54
4.5.5 Consumables and Supplies 54
4.5.6 Labor 54
4.5.7 Utilities 54
4.5.8 Residual Waste Handling and Disposal 55
4.5.9 Analytical Services 55
4.5.10 Maintenance and Modifications 55
Section 5 Data Quality Review 56
5.1 Deviations From TEP/QAPP 56
5.2 Summary of Data Evaluation and PARCC Criteria Evaluation 57
Section 6 Technology Status 59
References 60
Appendix A Sample Collection And Analysis Tables 61
Appendix B Data Used To Evaluate Project Primary Objectives 69
Appendix C Detailed Cost Element Spreadsheets 76
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Tables
Table Page
1-1 Bioreactor Treatment System Removal Efficiencies: Gravity Flow Operation 9
1-2 Bioreactor Treatment System Removal Efficiencies: Recirculation Operation 9
1 -3 Determination of Hazardous Waste Characteristics for Bioreactor Solid Waste Streams 9
2-1 Summary of Historical Metals of Concern 13
2-2 Removal Efficiencies for the Bioreactor Treatment System - Gravity Flow Operation 21
2-3 Removal Efficiencies for the Bioreactor Treatment System - Recirculation Operation 21
2-4 EPA Interim Discharge Standards 22
2-5 Results of the Student' s-t Test Statistical Analysis for Maximum Daily Effluent Data 23
2-6 Results of the Student' s-t Test Statistical Analysis for 4-Day Average Effluent Data 24
2-7 Gravity Flow Unit Operation Parameters 25
2-8 Recirculation Unit Operation Parameters 26
2-9 Gravity Flow Unit Operation Reaction Chemistry 27
2-10 Impact of Temperature on Sulfate Reduction and Iron Removal During Gravity Flow Operations 28
2-11 Recirculation Unit Operation Reaction Chemistry 29
2-12 Impact of Temperature on Sulfate Reduction and Iron Removal During Recirculation Operations 30
2-13 Gravity Flow Unit Operation Dissolved Metals Removal Efficiencies 31
2-14 Gravity Flow Unit Operation Metals and Sulfate Load Reduction 31
2-15 Recirculation Unit Operation Dissolved Metals Removal Efficiencies 33
2-16 Recirculation Unit Operation Metals and Sulfate Load Reduction 33
2-17 Gravity Flow Operation Solids Separation Efficiencies 34
2-18 Recirculation Operation Solids Separation Efficiencies 36
2-19 Bioreactor Treatment System Waste Characterization 39
3-1 Determination of Hazardous Waste Characteristics for Bioreactor Solid Waste Streams 45
3-2 Federal Applicable or Relevant and Appropriate Requirements for the Bioreactor Treatment System 47
3-3 Feasibility Study Criteria Evaluation for the Bioreactor Treatment System at Leviathan Mine 50
4-1 Summary of Total and Variable Costs for Each Mode of Operation 52
4-2 Summary of Cost Elements 53
Figures
Figure Page
1-1 Site Location Map 2
1-2 Bioreactor Treatment System, Gravity Flow Configuration Schematic 5
1-3 Bioreactor Treatment System, Recirculation Configuration Schematic 6
2-1 Site Layout 11
VI
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Acronyms, Abbreviations, and Symbols
ug/L Microgram per liter
umhos/cm Micromhos per centimeter
°C Degree Celsius
ACQR Air quality control region
AMD Acid mine drainage
AQMD Air quality management district
ARAR Applicable or relevant and appropriate requirements
ARCO Atlantic Richfield Company
ARD Acid rock drainage
CAA Clean Air Act
CERCLA Comprehensive Emergency Response, Compensation, and Liability Act
CFR Code of Federal Regulations
cm Centimeter
CUD Channel under drain
CWA Clean Water Act
DI Deionized water
DO Dissolved oxygen
DOT Department of Transportation
EE/CA Engineering evaluation cost analysis
EPA U.S. Environmental Protection Agency
HOPE High density polyethylene
HRT Hydraulic residence time
ICP
ITER
kg
kg/day
kW
Inductively coupled plasma
Innovative Technology Evaluation Report
Kilogram
Kilogram per day
Kilowatt
L
L/min
m3
MCL
MCLG
MD
mg/kg
Liter
Liter per minute
Cubic meter
Maximum contaminant level
Maximum contaminant level goal
Matrix duplicate
Milligram per kilogram
vn
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Acronyms, Abbreviations, and Symbols (continued)
mg/L Milligrams per liter
mL Milliliter
ml/L Milliliter per liter
ml/min Milliliter per minute
MS Matrix spike
mV Millivolt
NCP National Oil and Hazardous Substances Pollution Contingency Plan
NPDES National Pollutant Discharge and Elimination System
NRMRL National Risk Management Research Laboratory
O&M Operation and maintenance
ORP Oxidation reduction potential
OSHA Occupational Safety and Health Administration
PARCC Precision, accuracy, representativeness, completeness, and comparability
pH Negative logarithm of the hydrogen ion concentration
POTW Publicly-owned treatment works
PPE Personal protection equipment
PQL Practical quantitation limit
PUD Pit under drain
QA/QC Quality assurance/quality control
RCRA Resource Conservation and Recovery Act
RPD Relative percent difference
RWQCB California Regional Water Quality Control Board - Lahontan Region
SARA Superfund Amendment and Reauthorization Act
SCADA Supervisory Control and Data Acquisition
SDG Sample delivery group
SDWA Safe Drinking Water Act
SITE Superfund Innovative Technology Evaluation
SPLP Synthetic precipitation and leaching procedure
STLC Soluble threshold limit concentration
TCLP Toxicity characteristic leaching procedure
TDS Total dissolved solids
TEP/QAPP Technology Evaluation Plan/Quality Assurance Project Plan
Tetra Tech Tetra Tech EM Inc.
TOM Task order manager
TSD Treatment, storage, and disposal
TSS Total suspended solids
TTLC Total threshold limit concentration
UNR University of Nevada Reno
USAGE US Army Corp of Engineers
WET Waste extraction test
Vlll
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Conversion Factors
To Convert From
To
Length:
Area:
Volume:
Flow:
Mass:
Energy:
Power:
Temperature:
Centimeter
Meter
Kilometer
Square Meter
Liter
Cubic Meter
Cubic Meter
Liter per minute
Kilogram
Metric Ton
Kilowatt-hour
Kilowatt
"Celsius
Inch
Foot
Mile
Square Foot
Gallon
Cubic Foot
Cubic Yard
Gallon per minute
Pound
Short Ton
British Thermal Unit
Horsepower
("Fahrenheit + 32)
Multiply By
0.3937
3.281
0.6214
10.76
0.2642
35.31
1.308
0.2642
2.2046
1.1025
3413
1.34
1.8
IX
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Acknowledgements
This report was prepared under the direction of Mr. Edward Bates, the U.S. Environmental Protection
Agency (EPA) Superfund Innovative Technology Evaluation (SITE) project manager at the National Risk
Management Research Laboratory (NRMRL) in Cincinnati, Ohio; and Mr. Kevin Mayer, EPA Region IX.
This report was prepared by Mr. Matt Udell, Mr. Noel Shram, and Mr. Matt Wetter of Tetra Tech EM Inc.
(Tetra Tech) under Field Evaluation and Technical Support (FEATS) Contract No. 68-C-00-181. Field
sampling and data acquisition was performed by Mr. Udell, Mr. Joel Bauman, Mr. Matt Wetter, and Ms.
Sarah Piper of Tetra Tech.
This project consisted of the demonstration of an innovative technology under the SITE program to
evaluate the compost-free bioreactor treatment system developed by Drs. Glenn Miller and Tim Tsukamoto
of the University of Nevada Reno. The technology demonstration was conducted on acid rock drainage at
the Leviathan Mine Superfund site in Alpine County, California. The technology is currently being used as
an interim action at the site, pending completion of a remedial investigation, feasibility study, and record of
decision. This Innovative Technology Evaluation Report (ITER) interprets the data that were collected
during the two-year demonstration period and discusses the potential applicability of the technology to
other mine sites.
The cooperation of the following people during the technology demonstration and review of this report are
gratefully acknowledged: Mr. Scott Jacobs and Ms. Diana Bless of NRMRL, Drs. Glenn Miller and Tim
Tsukamoto of the University of Nevada Reno, Mr. Roy Thun and Mr. John Pantano of ARCO, and Mr.
Chris Stetler and Mr. Doug Carey of the California Regional Water Quality Control Board-Lahontan
Region.
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SECTION 1
INTRODUCTION
This section provides background information about the
Superfund Innovative Technology Evaluation (SITE) Program
and the SITE demonstration that was conducted at a mine site
in Alpine County, California, discusses the purpose of this
Innovative Technology Evaluation Report (ITER), and briefly
describes the technology that was evaluated. Key contacts are
listed at the end of this section for inquiries regarding
additional information about the SITE Program, the evaluated
technology, and the demonstration site.
1.1 Project Background
The U.S. Environmental Protection Agency (EPA), the states,
and the Federal Land Management Agencies all need better
tools to manage acid rock drainage (ARD) at abandoned mine
sites. Over a 21-month period during 2003 and 2005, EPA
evaluated the use of compost-free bioreactors for removal of
high concentrations of metals from ARD generated at
Leviathan Mine, located northwest of Monitor Pass in
northeastern Alpine County, California (Figure 1-1). The
compost-free bioreactor treatment SITE demonstration was
conducted by EPA under the SITE Program, which is
administered by EPA's National Risk Management Research
Laboratory (NRMRL), Office of Research and Development.
The SITE demonstration was conducted by EPA in
cooperation with EPA Region IX, the state of California, and
Atlantic Richfield Company (ARCO).
The compost-free bioreactor treatment system in operation at
Leviathan Mine is an improvement to current wood chip,
compost, and manure based bioreactors in place at many
facilities. The treatment system was installed by the
University of Nevada Reno (UNR) and ARCO from fall 2002
through the spring 2003. The bioreactor treatment system was
specifically designed by UNR to treat moderate flow rates of
ARD containing hundreds of milligrams per liter (mg/L) of
metals at a pH as low as 3.0. Without treatment, the ARD
from the mine would otherwise be released to the
environment. The SITE demonstration consisted of monthly
sampling events of the bioreactor treatment system with
periods of extended inaccessibility due to winter snowfall.
Throughout the SITE demonstration, EPA collected chemical
data on the system's influent and effluent streams,
documented metals removal and reduction in acidity within
the system's unit operations, and recorded operational
information pertinent to the evaluation of the treatment
system. EPA evaluated the treatment system based on
removal efficiencies for primary and secondary target metals,
comparison of effluent concentrations to interim discharge
standards (pre-risk assessment and record of decision)
mandated by EPA in 2002 and on the characteristics of
resulting metals-enriched solid wastes. Removal efficiencies
of individual unit operations were also evaluated. A summary
of the SITE demonstration and the results of the bioreactor
treatment technology evaluation are presented in Sections 2
through 5 of this report.
1.2 The SITE Demonstration Program and
Reports
In 1980, the U.S. Congress passed the Comprehensive
Environmental Response, Compensation, and Liability Act
(CERCLA), also known as Superfund. CERCLA is
committed to protecting human health and the environment
from uncontrolled hazardous waste sites. In 1986, CERCLA
was amended by the Superfund Amendments and
Reauthorization Act (SARA). These amendments emphasize
the achievement of long-term effectiveness and permanence of
remedies at Superfund sites. SARA mandates the use of
permanent solutions, alternative treatment technologies, or
resource recovery technologies, to the maximum extent
possible, to clean up hazardous waste sites.
State and Federal agencies, as well as private parties, have for
several years now been exploring the growing number of
innovative technologies for treating hazardous wastes. EPA
has focused on policy, technical, and informational issues
related to the exploring and applying new remediation
technologies applicable to Superfund sites. One such
initiative is EPA's SITE Program, which was established to
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Lake
Tahoe
/ *
Study Area
Scale 1" = 5 miles
Figure 1-1. Site Location Map
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accelerate the development, demonstration, and use of
innovative technologies for site cleanups. The SITE
Program's primary purpose is to maximize the use of
alternatives in cleaning hazardous waste sites by encouraging
the development and demonstration of new, innovative
treatment and monitoring technologies. It consists of three
major elements: the Demonstration Program, the Consortium
for Site Characterization Technologies, and the Technology
Transfer Program.
The objective of the Demonstration Program is to develop
reliable performance and cost data on innovative technologies
so that potential users can assess the technology's site-specific
applicability. Technologies evaluated are either available
commercially or are close to being available for full-scale
remediation of Superfund sites. SITE demonstrations usually
are conducted at hazardous waste sites under conditions that
closely simulate full-scale remediation conditions, thus
assuring the usefulness and reliability of the information
collected. Data collected are used to assess: (1) the
performance of the technology; (2) the potential need for pre-
and post treatment of wastes; (3) potential operating problems;
and (4) the approximate costs. The demonstration also
provides opportunities to evaluate the long term risks and
limitations of a technology.
At the conclusion of a SITE demonstration, EPA prepares a
Demonstration Bulletin, Technology Capsule, and an ITER.
These reports evaluate all available information on the
technology and analyze its overall applicability to other
potential sites characteristics, waste types, and waste matrices.
Testing procedures, performance and cost data, and quality
assurance and quality standards are also presented. The
Technology Bulletin consists of a one to two page summary of
the SITE demonstration and is prepared as a mailer for public
notice. The Technology Bulletin provides a general overview
of the technology demonstrated, results of the demonstration,
and telephone numbers and e-mail address for the EPA project
manager in charge of the SITE evaluation. In addition,
references to other related documents and reports are
provided. The Technology Capsule consists of a more in-
depth summary of the SITE demonstration and is usually
about 10 pages in length. The Technology Capsule presents
information and summary data on various aspects of the
technology including applicability, site requirements,
performance, process residuals, limitations, and current status
of the technology. The Technology Capsule is designed to
help EPA remedial project managers and on-scene
coordinators, contractors, and other site cleanup managers
understand the types of data and site characteristics needed to
effectively evaluate the technology's applicability for cleaning
Superfund sites. The final SITE document produced is the
ITER. The ITER consists of an in-depth evaluation of the
SITE demonstration including details on field activities and
operations, performance data and statistical evaluations,
economic analysis, applicability, and effectiveness, as
discussed in the following section.
1.3 Purpose of the Innovative Technology
Evaluation Report
The ITER is designed to aid decision-makers in evaluating
specific technologies for further consideration as applicable
options in a particular cleanup operation. The ITER should
include a comprehensive description of the SITE
demonstration and its results, and is intended for use by EPA
remedial project managers, EPA on-scene coordinators,
contractors, and other decision-makers carrying out specific
remedial actions.
To encourage the general use of demonstrated technologies,
EPA provides information regarding the applicability of each
technology to specific sites and wastes. The ITER includes
information on cost and desirable site-specific characteristics.
It also discusses advantages, disadvantages, and limitations of
the technology. However, each SITE demonstration evaluates
the performance of a technology in treating a specific waste
matrix at a specific site. The characteristics of other wastes
and other sites may differ from the characteristics at the
demonstration site. Therefore, a successful field
demonstration of a technology at one site does not necessarily
ensure that it will be applicable at other sites. Data from the
field demonstration may require extrapolation for estimating
the operating ranges in which the technology will perform
satisfactorily. Only limited conclusions can be drawn from a
single field demonstration.
This ITER provides information on new approaches to the use
of a compost-free bioreactor treatment system to reduce the
concentration of toxic metals and acidity in ARD at Leviathan
Mine, and is a critical step in the development and
commercialization of compost-free bioreactor treatment
systems for use at other applicable mine sites.
1.4 Technology Description
Biological treatment of ARD relies on the biologically
mediated reduction of sulfate to sulfide followed by metal
sulfide precipitation. Biologically promoted sulfate-reduction
has been attributed primarily a consortium of sulfate-reducing
bacteria, which at Leviathan Mine utilizes ethanol as a carbon
substrate to reduce sulfate to sulfide. This process generates
hydrogen sulfide, elevates pH to about 7, and precipitates
divalent metals as metal sulfides. The following general
equations describe the sulfate-reduction and metal sulfide
precipitation processes.
2CH3CH2OH + 3SO42" -» 3HS" + 3HCO3" + 3H2O
(1)
2CH3CH2OH + SO42" -» 2 CH3COQ- + HS~ + H2O (2)
HS'+M2+-»MS + 2H+ (3)
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Here ethanol is the carbon source and SO4" is the terminal
electron acceptor in the electron transport chain of sulfate-
reducing bacteria. Reaction No.l causes an increase in
alkalinity and a rise in pH, while reaction No.2 results in the
generation of acetate rather than complete oxidation to
carbonate. HS~ then reacts with a variety of divalent metals
(M2+), resulting in a metal sulfide (MS) precipitate.
The reduction of sulfate to sulfide requires 8 electrons:
H2SO4 + 8H+ + 8e~ -» H2S + 4H2O
(4)
Ethanol contributes 12 electrons per molecule oxidized,
assuming complete oxidation to carbon dioxide.
3H2O + C2H5OH -» Ue + 2CO2 + 12H+
(5)
However, incomplete oxidation of ethanol to acetate yields
only 4 electrons per molecule oxidized.
H2O + C2H5OH -» 4e~ + C2H3OOH + 4H+
(6)
The moles of ethanol consumed per mole of sulfate reduced in
the bioreactors at Leviathan Mine suggest that incomplete
oxidation of ethanol is the predominant reaction.
Compost-Free Bioreactor System Overview: At Leviathan
Mine, the compost-free bioreactor treatment system consists
of ethanol and sodium hydroxide feed stocks, a pretreatment
pond, two bioreactors, a settling pond, a flushing pond, and an
aeration channel. The heart of the treatment system is the
two compost-free, sulfate-reducing bioreactors. A blanket of
manure was added to the base of each bioreactor to support
the startup of each bioreactor. The bioreactors are lined ponds
filled with river rock (Figures 1-2 and 1-3). River rock was
selected because of the stability of the matrix and the ease at
which metal sulfide precipitates can be flushed from the
matrix to the flushing pond. Each bioreactor consists of three
influent distribution loops and three effluent collection loops
located near the top, in the middle, and just above the bottom
of the bioreactor to precisely control flow within the
bioreactor media. ARD water can be drawn upward or
downward through the aggregate to one of three effluent
collection lines located at the opposite end of each bioreactor
(Figures 1-2 and 1-3).
The system was designed to treat ARD by gravity flow
through successive sulfate-reducing bioreactors and
precipitation of metal sulfides in a continuous flow settling
pond (Figure 1-2). During the demonstration, an alternative
mode of operation (recirculation) was also evaluated, which
involved the direct contact of influent ARD with sulfide rich
water from the bioreactors and precipitation of metal sulfides
in the settling pond. A portion of the pond supernatant
containing excess sulfate is then pumped to the head of the
bioreactor system to generate additional sulfides (Figure 1-3).
Compost-Free Bioreactor Operation: Operated in gravity
flow mode (Figure 1-2), influent ARD passes through a flow
control weir at flow rates ranging from 25 to 47 liters per
minute (L/min), where sodium hydroxide is added to adjust
the pH to approximately 4 to maintain a favorable
environment for sulfate-reducing bacteria and ethanol is added
to provide a carbon source for reducing equivalents for the
sulfate-reducing bacteria. Precipitates that are formed at this
state are settled out in the pretreatment pond. ARD flows
through Bioreactor No. 1 and Bioreactor No.2 to reduce sulfate
to sulfide. Excess sulfide generated in the first bioreactor is
passed, along with partially treated ARD water, through to the
second bioreactor for additional metals removal. Effluent
from the second bioreactor discharges to a continuous flow
pond for extended settling of metal sulfide precipitates.
Sodium hydroxide is added to the bioreactor effluent to
consume mineral acidity and convert bisulfide to sulfide,
which is necessary to precipitate iron as iron sulfide in the
settling pond.
Operated in recirculation mode (Figure 1-3), metal-rich ARD
is routed around the two bioreactors to a flow control vault at
the head of the continuous flow settling pond. The untreated
ARD is mixed with sodium hydroxide and sulfide rich water
from bioreactor No.2, and is then discharged to the settling
pond. The combination of a neutral pH condition and high
sulfide concentration promotes rapid generation and
precipitation of metal sulfides in the settling pond rather than
in the two bioreactors. Precipitation of metal sulfides
downstream of the two bioreactors greatly reduces
precipitation in the bioreactors and the need for flushing and
the associated stress on the two bioreactors. A portion of the
pond supernatant containing excess sulfate is then pumped to
bioreactor No.l at flow rates ranging from 114 to 227 L/min
(influent to recirculation ratio of 1:2 to 1:6). Ethanol is added
to the influent vault at the head of bioreactor No.l. Sulfate-
rich and metal-poor water from the holding pond then flows
through the two bioreactors to promote additional sulfate
reduction to sulfide. The pH of the supernatant recirculated
through the bioreactors is near neutral, providing optimal
conditions for sulfate-reducing bacteria growth. The system
operated in recirculation mode requires about 49 percent less
sodium hydroxide addition and 14 percent more ethanol than
the gravity flow mode of operation.
In both modes of operation, the effluent from the continuous
flow settling pond flows through a rock lined aeration channel
to promote gas exchange prior to effluent discharge. Metal
sulfide precipitate slurry is periodically flushed from the two
bioreactors to prevent plugging of the river rock matrix. The
slurry is sent to a flushing pond for extended settling. Metal
sulfide precipitates are periodically pumped out of the settling
and flushing ponds and dewatered using bag filters. Metals in
bag filter solids did not exceed Federal or state of California
standards for characterization as a hazardous waste.
-------
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Figure 1-3. Bioreactor Treatment System, Recirculation Configuration Schematic
-------
1.5 Key Findings
The bioreactor treatment system is extremely effective at
neutralizing acidity and reducing metals content in ARD, with
resulting effluent streams that meet EPA interim discharge
standards for the primary target metals and the secondary
target metals. The bioreactor treatment system operated in
gravity flow mode from November 2003 through mid-May
2004 treating 9.24 million liters (2.44 million gallons) of ARD
using 9,236 liters (L) of sodium hydroxide and 4,466 L of
ethanol. The bioreactor treatment system operated in the
recirculation mode from mid-May 2004 through July 2005
treating 22.1 million liters (5.81 million gallons) of ARD
using 22,029 L of sodium hydroxide and 10,617 L of ethanol.
Although the influent concentrations for the primary target
metals were up to 580 fold above EPA interim discharge
standards, both modes of treatment system operation were
successful in reducing the concentrations of the primary target
metals in the ARD to between 1 and 43 fold below the
discharge standards. Internal trials run to refine base addition
requirements and to evaluate various sources of base addition
lead to significant excursions of effluent iron concentrations
above the EPA interim discharge standards during a portion of
the evaluation. However, after base optimization during
gravity flow operations effluent iron concentrations met
discharge standards. Iron also exceeded discharge standards
during recirculation operations when base addition was
stopped due to equipment failure or lack of adequate base
supply. In addition, the concentrations of the secondary target
metals, with the exception of selenium, were reduced to below
the discharge standards. For the gravity flow mode of
treatment system operation, the average removal efficiency for
the primary target metals was 94 percent over 6 sampling
events. For the recirculation mode of treatment system
operation, the average removal efficiency for the primary
target metals was 96 percent over 7 sampling events.
Removal efficiencies for arsenic were not calculated because
the influent and effluent metals concentrations were not
statistically different (p-value exceeded 0.05). In addition, the
concentration of arsenic in system influent was well below
discharge standards.
Average removal efficiencies for secondary target metals
ranged from 41 to 99 percent in both modes of operation;
however, removal efficiencies were not calculated for arsenic,
cadmium, chromium, lead, and selenium as the influent and
effluent concentrations were not statistically different (p-value
exceeded 0.05). In the case of arsenic, cadmium, chromium,
lead, and selenium in the ARD, concentrations were near or
below the EPA interim discharge standards in the influent;
therefore, the treatment system was not optimized for removal
of these metals resulting in lower removal efficiencies.
Removal efficiencies for sulfate ranged from 8 to 35 percent
with an average reduction in sulfate of 17 percent. There was
on average a 9 percent increase in sulfate removal during
recirculation operations when compared to gravity flow
operations.
Tables 1-1 and 1-2 present the average and range of removal
efficiencies for filtered influent and effluent samples collected
from the treatment system during both gravity flow and
recirculation modes of operation. A summary of the average
influent and effluent metals concentrations for each mode of
operation is presented. The results of a comparison of the
average effluent concentration for each metal to the EPA
interim discharge standards is also presented; where a "Y"
indicates that either the maximum concentration (based on a
daily composite of three grab samples) and/or the average
concentration (based on four daily composite samples) was
exceeded; and an "N" indicates that neither discharge standard
was exceeded.
The bioreactor treatment system produced a relatively small
quantity of metal sulfide sludge. During operation from
November 2003 through July 2005, the bioreactor generated
about 14.2 dry tons (12,900 kilograms [kg]) of sludge
consisting mainly of iron sulfide. This equals about 1.7 dry
tons (1,550 kg) of sludge per million gallons (0.45 dry ton
[410 kg] per million liters) of ARD treated. The solid waste
residuals produced by the treatment system were analyzed for
potential hazardous waste characteristics. Total and leachable
metals analyses were performed on the solid wastes for
comparison to California and federal hazardous waste
classification criteria. The characteristics of the solid waste
stream are presented in Table 1-3. None of the solid wastes
were found to be hazardous or a threat to water quality;
however, the solids were disposed of off site pending
designation of an on-site disposal area.
In general, the limitations of the bioreactor treatment system
implemented at Leviathan Mine were not related to the
applicability of the technology, but rather to operational issues
due to weather conditions (extreme cold and winter snow
pack), maintenance problems (recirculation pump failures and
reagent delivery), and the remoteness of the site (power
supply, maintaining adequate supplies of consumables and
replacement equipment). The technology is not limited by the
sub-freezing temperatures encountered in the high Sierra
Nevada during the winter months. However, biological
activity did slow resulting is decreased sulfate reduction to
sulfide. Effluent discharge standards were generally met as
the flow of ARD entering the bioreactor treatment system also
decreased during the winter.
1.6 Key Contacts
Additional information on this technology, the SITE Program,
and the evaluation site can be obtained from the following
sources:
-------
EPA Contacts:
State of California Contact:
Edward Bates, EPA Project Manager
U.S. Environmental Protection Agency
National Risk Management Research Laboratory
Office of Research and Development
26 West Martin Luther King Jr. Drive
Cincinnati, OH 45268
(513)569-7774
bates.edward(@,epa. gov
Kevin Mayer, EPA Remedial Project Manager
U.S. Environmental Protection Agency Region 9
75 Hawthorne Street, SFD-7-2
San Francisco, CA 94105
(415)972-3176
maver.kevin(@,epa. gov
ARCO Contact:
Roy Thun, Project Manager
BP Atlantic Richfield Company
6 Centerpointe Drive, Room 6-164
La Palma, CA 90623
(661) 287-3855
thunril(g),bp. com
Richard Booth, Project Manager
California Regional Water Quality Control Board
Lahontan Region
2501 Lake Tahoe Blvd.
South Lake Tahoe, CA 96150
(530) 542-5470
RBooth(@,waterboards.ca.gov
University of Nevada-Reno Contacts:
Drs. Glenn Miller and Tim Tsukamoto
Department of Natural Resources and Environmental Science
University of Nevada-Reno, Mail Stop 199
Reno, NV 89557-0187
(775)784-4413
gcmiller(@,unr.edu
timothyt(@,unr.edu
-------
Table 1-1. Bioreactor Treatment System Removal Efficiencies: Gravity Flow Configuration
Target
Metal
Number of
Sampling
Events
Average
Filtered Influent
Concentration
(MS/L)
Standard
Deviation
Average
Filtered Effluent
Concentration
(M8/L)
Standard
Deviation
Exceeds
Discharge
Standard
(Y/N)
Average
Removal
Efficiency (1)
(%)
Range of
Removal
Efficiencies
(%)
Primary Target Metals
Aluminum
Arsenic
Copper
Iron
Nickel
6
6
6
6
6
37,467
2.1
691
117,167
487
2,011
0.64
51.2
6,242
33.5
103
4.73
4.8
4,885
65.5
78.8
4.0
1.6
4,771
35.9
N
N
N
Y
N
99.7
NC
99.3
95.8
86.6
99.5 to 99.9
NC
99.1 to 99.7
65.6 to 99.9
72.1 to 92. 6
Secondary Target Metals
Cadmium
Chromium
Lead
Selenium
Zinc
6
6
6
6
6
0.61
12.2
3.64
13.9
715
0.27
8.9
2.5
3.1
47.1
<0.21
7.83
4.69
11.2
15.8
0.07
6.6
2.9
2.6
6.8
N
N
N
Y
N
65.3
NC
NC
NC
97.8
42.5 to 79
NC
NC
NC
95.9 to 98.6
(1) Average removal efficiency calculated using the average influent and average effluent concentration data.
NC = Not calculated as influent and effluent concentrations were not statistically different
|xg/L = Microgram per liter
Table 1-2. Bioreactor Treatment System Removal Efficiencies: Recirculation Configuration
Target
Metal
Number of
Sampling
Events
Average
Filtered Influent
Concentration
(U2/L)
Standard
Deviation
Average
Filtered Effluent
Concentration
(H2/L)
Standard
Deviation
Exceeds
Discharge
Standard
(Y/N)
Average
Removal
Efficiency™
(%)
Range of
Removal
Efficiencies
(%)
Primary Target Metals
Aluminum
Arsenic
Copper
Iron
Nickel
7
7
7
7
7
40,029
7.43
795
115,785
529
4,837
6.5
187
13,509
34.1
52.7
6.51
4.59
2,704
69.7
25.7
4.9
3.2
3,000
44.2
N
N
N
Y
N
99.9
NC
99.4
97.7
86.8
99.7 to 99.9
NC
98.8 to 99.8
92.8 to 99.7
71.0 to 96.4
Secondary Target Metals
Cadmium
Chromium
Lead
Selenium
Zinc
7
7
7
7
7
0.60
11.1
4.17
11.5
776
0.50
6.3
2.3
5.1
51.7
<0.20
6.38
2.45
8.49
8.91
0.09
5.2
1.6
3.6
7.4
N
N
N
Y
N
NC
42.5
41.3
NC
98.9
NC
21.2 to 84.8
22.0 to 57.1
NC
97.7 to 99.8
(1) Average removal efficiency calculated using the average influent and average effluent concentration data.
NC = Not calculated as influent and effluent concentrations were not statistically different
Hg/L = Microgram per liter
Table 1-3. Determination of Hazardous Waste Characteristics for Bioreactor Solid Waste Streams
Treatment
System
Bioreactor
Treatment
System
Solid Waste Stream
Dewatered Sludge
Pretreatment Pond
Settling Pond
Flushing Pond
Total Solid
Waste Generated
4.3 dry tons
Moved into Flushing Pond
10 dry tons (estimated)
4.3 dry tons (estimated)
TTLC
Pass or
Fail
P
P
P
P
STLC
Pass or
Fail
P
P
P
P
TCLP
Pass or
Fail
P
P
P
P
Waste Handling Status
Off-site Disposal
Moved into Flushing Pond
Pending Filtration
Pending Filtration
STLC = Soluble limit threshold concentration TTLC = Total threshold limit concentration
TCLP = Toxicity characteristic leaching procedure 1 dry ton = 907 kilograms
-------
SECTION 2
TECHNOLOGY EFFECTIVENESS
The following sections discuss the effectiveness of the
compost-free bioreactor treatment technology demonstrated at
the Leviathan Mine site. The discussion includes a
background summary of the site, description of the technology
process and the evaluation approach, a summary of field
activities, and results of the evaluation.
2.1 Background
Leviathan Mine is a former copper and sulfur mine located
high on the eastern slopes of the Sierra Nevada Mountain
range, near the California-Nevada border. Intermittent mining
of copper sulfate, copper, and sulfur minerals since the mid-
18605 resulted in extensive acid mine drainage (AMD) and
ARD at Leviathan Mine. During the process of converting
underground workings into an open pit mine in the 1950s,
approximately 22 million tons of overburden and waste rock
were removed from the open pit mine and placed in the Aspen
Creek drainage, contributing ARD to the Aspen Seep.
Oxidation of sulfur and sulfide minerals within the mine
workings and waste rock forms sulfuric acid (H2SO4), which
liberates toxic metals from the mine wastes creating AMD and
ARD. AMD and ARD at Leviathan Mine contain high
concentrations of toxic metals and historically flowed directly
to Leviathan Creek without capture or treatment.
2.1.1 Site Description
The Leviathan Mine property occupies approximately 102
hectares in the Leviathan Creek basin, which is located on the
northwestern flank of Leviathan Peak at an elevation ranging
from 2,134 to 2,378 meters ( 7,000 to 7,800 feet) above mean
sea level. Access to the mine site is provided by unpaved
roads (United States Forest Service Road 52) from State
Highway 89 on the southeast and from US Highway 395 south
of Gardnerville, Nevada, on the northeast. Of the total
property, approximately 1 million square meters (247 acres)
are disturbed by mine-related activities. With the exception of
approximately 85 thousand square meters on Forest Service
lands, mine-related workings are located on property owned
by the State of California. Figure 2-1 presents a map showing
the layout of the Leviathan Mine site.
The mine site lies within the Bryant Creek watershed and is
drained by Leviathan and Aspen creeks, which combine with
Mountaineer Creek 3.5 kilometers below the mine to form
Bryant Creek, a tributary to the East Fork of the Carson River.
The terrain in the Leviathan Creek basin includes rugged
mountains and high meadowlands. The area has a climate
typical of the eastern slope of the Sierra Nevada range
characterized by warm dry summers with the bulk of the
precipitation occurring as winter snow. Vegetation at the site
is representative of the high Sierra Nevada floristic province,
with scattered stands of mixed conifers or Jeffery pine on
north-facing slopes. Aspen groves border parts of Leviathan
and Aspen creeks, while shrub communities dominate flats
and south facing slopes.
Precipitation in the area around Leviathan Mine varies with
elevation and distance from the crest of the Sierra Nevada
mountain range. The heaviest precipitation is from November
through April. Annual precipitation on western slopes of the
Sierra Nevada averages about 140 centimeters (cm), varying
from a low of about 51 cm to highs estimated in the range of
165 to 178 cm in some of the more remote mountain areas
near the easterly boundary of Leviathan Creek basin. There is
little precipitation data for the mine site; therefore, a mean
annual precipitation was estimated at 70.6 cm per year using
local weather monitoring stations provided by the U.S.
Geological Survey (EMC2 2004a). A large percentage of the
precipitation which falls during the winter months occurs as
snow. Snow pack accumulates from about November through
March, with the maximum accumulation generally occurring
about April 1. The average April 1 snow line is below an
elevation of 1,525 meters. The snow pack generally begins to
melt during March, but the period of major snowmelt activity
is typically April through July. Winter snow pack is the
source of about 50 percent of annual runoff.
10
-------
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Figure 2-1. Site Layout
LEGEND
UWtaOtttMEWI
11
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2.1.2 History of Contaminant Release
Prior to 1984, the various sources of AMD and ARD
discharging from the Leviathan Mine site included AMD from
the floor of the mine pit flowing west into Leviathan Creek;
AMD from Adit No. 5, located below the mine pit, flowing
west into Leviathan Creek; ARD from the Delta Area (also
known as Delta Seep), located adjacent to Leviathan Creek
along the western edge of the mine area, flowing northwest
into Leviathan Creek; and ARD from Aspen Seep, located
along the northern portion of the site within the overburden
piles, flowing north into Aspen Creek. Historically, the
concentrations of five primary target metals, aluminum,
arsenic, copper, iron, and nickel in the AMD and ARD
released to Leviathan and Aspen creeks have exceeded EPA
interim (pre-risk assessment and record of decision) discharge
standards up to 3,000 fold. Historical concentrations for each
source of AMD and ARD are presented in Table 2-1.
When AMD was inadvertently released in large quantities
from the Leviathan Mine site in the 1950s, elevated
concentrations of toxic metals resulted in fish and insect kills
in Leviathan Creek, Bryant Creek, and the east fork of the
Carson River. The absence of trout among the fish killed in
Bryant Creek and in the east fork of the Carson River
immediately downstream from Bryant Creek indicated that
continuous discharges from mining operations had eliminated
the more sensitive trout fisheries that existed prior to open-pit
operations. Various efforts were made between 1954 and
1975 to characterize the impacts of Leviathan Mine on water
quality at and below the site during and after open-pit mining
operations (California Regional Water Quality Control Board
- Lahontan Region [RWQCB] 1995).
2.1.3 Previous Actions
The Leviathan Mine Pollution Abatement Project was initiated
by the state of California in 1979 with the preparation of a
feasibility study. In 1982, the State contracted the design of
the Pollution Abatement Program, which was then
implemented in 1984 with physical actions that significantly
reduced the quantity of toxic metals discharging from the mine
site. Work conducted at the site included regrading over-
burden piles to prevent impounding and infiltration of
precipitation and promote surface runoff; partially filling and
grading the open pit; constructing a surface water collection
system within the reworked mine pit to redirect
uncontaminated surface water to Leviathan Creek;
constructing a pit under drain (PUD) system beneath the pit
(prior to filling and grading) to collect and divert surface water
seeping into the pit floor; construction of five
storage/evaporation ponds to collect discharge from the PUD
and Adit No. 5; and rerouting Leviathan Creek by way of a
concrete diversion channel to minimize contact of creek water
with waste rock piles. During pond construction, previously
unrecognized springs were encountered. To capture the
subsurface flow from these springs, a channel under drain
(CUD) was constructed beneath Leviathan Creek (RWQCB
1995). Discharges of ARD to Aspen Creek were not
addressed as a part of the project. Figure 2-1 presents a
detailed site map of the mine site as it exists in 2004, after
implementation physical work conducted at the mine site.
Starting in 1996, pilot studies were conducted by UNR in
coordination with the state of California to precipitate metals
in ARD discharging from Aspen Seep using surf ate-reducing
bacteria. The pilot studies evaluated wood chip and rock
substrates, base addition, and a solids collection and removal
strategies. The information developed during the pilot studies
resulted in the design and construction of a full-scale compost-
free bioreactor treatment system in the fall of 2002 through the
summer of 2003.
Starting in 1997, EPA initiated enforcement actions at the
Leviathan Mine site to further mitigate potential releases of
AMD and ARD from the various sources. In response to
EPA's 1997 action memorandum, the state of California
implemented the active lime treatment system in 1999 to treat
AMD that collects in the retention ponds. Since the
installation of the active lime treatment system in 1999, no
releases of AMD have occurred from the retention ponds to
Leviathan Creek. In response to EPA's July 21, 2001, action
memorandum, ARCO implemented a semi-passive alkaline
lagoon treatment system to treat ARD from the CUD. Figure
2-1 presents a detailed site map of the mine site after
construction of the lime and bioreactor treatment systems.
In 2002, EPA prepared an additional action memorandum
setting interim discharge standards for the five primary target
metals and five secondary water quality indicator metals for
discharge of treated water from the treatment systems to
Leviathan Creek (EPA 2002). Discharge standards for the
five primary metals of concern are presented in Table 2-1.
The maximum daily standard equals the highest concentration
of a target metal to which aquatic life can be exposed for a
short period of time without deleterious effects. The four-day
average standard equals the highest concentration of a target
metal to which aquatic life can be exposed for an extended
period of time (4 days) without deleterious effects.
2.2 Process Description
The bioreactor treatment system evaluated at Leviathan Mine
was set up to treat ARD captured from Aspen Seep at the mine
site. The treatment system consists of one 7,600 L ethanol and
three 3,800 L sodium hydroxide feed stock tanks, a
pretreatment pond, two bioreactors, a settling pond, a flushing
pond, and an aeration channel. The system was designed to
treat ARD by gravity flow through successive sulfate-reducing
bioreactors and precipitation of metal sulfides in a continuous
flow settling pond (Figure 1-2). System design flow is 114
L/min. During the demonstration, an alternative mode of
12
-------
Table 2-1. Summary of Historical Metals of Concern
Analyte
Number of
Samples
Detection
Percentage
Minimum
Concentration
(mg/L)
Maximum
Concentration
(mg/L)
Mean
(mg/L)
Standard
Deviation
(mg/L)
Discharge Standards
Maximum (a)
(mg/L)
Average (b)
(mg/L)
Aspen Seep
Aluminum
Arsenic
Copper
Iron
Nickel
34
34
21
34
34
100
97.1
95.2
100
97.1
0.073
0
0
0.11
0
65
0.1
1.8
580
0.75
51
0.03
1.3
124
0.55
14.2
0.03
0.55
113
0.18
4.0
0.34
0.026
2.0
0.84
2.0
0.15
0.016
1.0
0.094
Adit No. 5
Aluminum
Arsenic
Copper
Iron
Nickel
46
45
28
45
46
100
100
100
100
100
220
8.6
0.88
120
4.4
430
28
4.2
2,400
10
310
16.2
1.5
815
6.1
63.6
5.5
0.97
369
1.6
4.0
0.34
0.026
2.0
0.84
2.0
0.15
0.016
1.0
0.094
Combination of Ponds 1, 2 North, and 2 South
Aluminum
Arsenic
Copper
Iron
Nickel
29
27
9
32
27
100
100
100
100
100
3
0.192
2.4
4
1.2
4,900
92
35
6,600
61
1,199
27.1
8.1
1,734
17.5
1,036
19.9
10.2
1,450
12
4.0
0.34
0.026
2.0
0.84
2.0
0.15
0.016
1.0
0.094
Channel Under Drain
Aluminum
Arsenic
Copper
Iron
Nickel
60
61
37
61
61
100
100
97.3
100
100
29
0.091
0
270
0.21
68
0.80
0.13
460
3.4
48
0.45
0.026
367
1.95
10.6
0.19
0.035
59.2
0.79
4.0
0.34
0.026
2.0
0.84
2.0
0.15
0.016
1.0
0.094
Delta Seep
Aluminum
Arsenic
Copper
Iron
Nickel
18
19
17
19
18
100
84.2
35.3
100
100
0.89
0.052
0.0018
18.0
0.41
4.7
0.094
0.14
33.0
0.563
1.68
0.067
0.032
21.5
0.49
0.88
0.012
0.054
3.9
0.05
4.0
0.34
0.026
2.0
0.84
2.0
0.15
0.016
1.0
0.094
(a) Based on a daily composite of three grab samples
(b) Based on the average of four daily composite samples
mg/L = Milligram per liter
operation (recirculation) was also evaluated, which involved
the direct contact of ARD with sulfide rich water from the
bioreactors and precipitation of metal sulfides in the settling
pond. A portion of the settling pond supernatant containing
excess sulfate is then pumped to the head of the bioreactor
system to generate additional sulfides (Figure 1-3).
The heart of the treatment system is the two compost-free,
sulfate-reducing bioreactors. The bioreactors are ponds lined
with 60 mil high density polyethylene (HDPE) and filled with
20 to 40 cm river rock. River rock was selected because of the
ease at which precipitates can be flushed through the matrix
and the stability of the matrix. A blanket of manure was
added to the base of each bioreactor to support the startup of
each bioreactor. Each bioreactor consists of three 10 cm
diameter influent distribution lines and three 10 cm effluent
collection lines. The distribution and collection lines are
located near the top, in the middle, and just above the bottom
of the bioreactor to precisely control flow within the
bioreactor media. ARD water can be drawn upward or
downward through the aggregate to one of three effluent
collection lines located at the opposite end of each bioreactor
(Figures 1-2 and 1-3).
Influent to the treatment system consists of ARD discharged
from Aspen Seep. In gravity flow mode (Figure 1-2), influent
13
-------
ARD from Aspen Seep passes through a flow control weir at
flow rates ranging from 25 to 91 L/min, where a 25 percent
sodium hydroxide solution (0.26 [ml/L] milliliter per liter or
83 mg/L) is added to adjust the pH from 3.1 to approximately
4 to maintain a favorable environment for sulfate-reducing
bacteria and ethanol (0.43 ml/L or 339 mg/L) is added to
provide a carbon source for reducing equivalents for the
sulfate-reducing bacteria. The dosed influent discharges into a
pretreatment pond (28 m3 [cubic meter], 4 hour hydraulic
residence time [HRT] at 114 L/min) to allow sufficient time
for reagent contact and to stabilize the flow to the head of
Bioreactor No.l. A small volume of metal precipitation also
occurs within the pretreatment pond. ARD from the
pretreatment pond then flows through Bioreactor No.l (354
m3 total volume, 150 m3 active volume) and Bioreactor No.2
(200 m3 total volume, 85 m3 active volume) to reduce sulfate
to sulfide. The HRT for the two bioreactors are 22 hours for
Bioreactor No.l and 13 hours for Bioreactor No.2 at a design
flow rate of 114 L/min. Excess sulfide generated in the first
bioreactor is passed, along with partially treated ARD water,
through to the second bioreactor for additional metals
removal. Effluent from the second bioreactor discharges to a
continuous flow pond (465 m3 volume, 68 hour HRT at 114
L/min) for extended settling of metal sulfide precipitates. A
twenty-five percent sodium hydroxide solution (0.85 ml/L or
270 mg/L) is added to the bioreactor effluent prior to the
continuous flow settling pond to reduce acidity, raise the pH to
7, and enhance metal sulfide precipitation.
Operated in recirculation mode (Figure 1-3), metal-rich ARD
influent from Aspen Seep passes through a flow control weir
at which point the ARD flow is routed around the two
bioreactors to a flow control vault at the head of the
continuous flow settling pond. The untreated ARD is mixed
with the sulfide-rich water from bioreactor No.2 followed by
25 percent sodium hydroxide solution (0.5 ml/L or 159 mg/L),
and is then discharged to the settling pond. The combination
of a neutral pH condition and high sulfide concentrations
promotes rapid precipitation of metal sulfides in the settling
pond rather than in the two bioreactors. Precipitation of a
majority of the metal sulfides downstream of the two
bioreactors reduces precipitate formation in the bioreactors
and the need for flushing and the associated stress on bacteria
in the two bioreactors. A portion of the pond supernatant
containing excess sulfate is then pumped to a holding pond at
flow rates ranging from 114 to 227 L/min. Ethanol (0.5 ml/L
or 395 mg/L) is added to the discharge from the holding pond,
just prior to the head of bioreactor No.l. Sulfate-rich and
metal-poor water from the holding pond then flows through
the two bioreactors to promote additional sulfate reduction to
sulfide. The pH of the supernatant recirculated through the
bioreactors is near neutral, providing optimal conditions for
sulfate-reducing bacteria growth (Tsukamoto 2005a). The
system operated in recirculation mode requires about 49
percent less sodium hydroxide and 14 percent more ethanol
than the gravity flow mode of operation.
During both modes of operation, the effluent from the
continuous flow settling pond then flows through a rock lined
aeration channel (46 meter long by 0.6 meter wide) to promote
gas exchange prior to effluent discharge. Precipitate slurry is
periodically flushed from the two bioreactors to prevent
plugging of the river rock matrix. The slurry is sent to a
flushing pond (510m3 volume, 75 hour HRT at 114 L/min) for
extended settling. The flushing pond can also be used for
extended settling of the continuous flow settling pond effluent
in the event of a system upset. Settled solids are periodically
pumped out of the settling and flushing ponds and dewatered
using 3 meter by 4.6 meter spun fabric bag filters. The bag
filtration process relies on the build up of filter cake on the
inside of each bag to remove progressively smaller particles.
Effluent from the bag filters, including soluble metals and
particles too small to be captured, flows by gravity back into
the flushing pond. Metals in bag filter solids did not exceed
Federal or state of California standards for characterization as
a hazardous waste. The total system HRT is 107 hours at
maximum design flow of 114 L/min, and 352 hours at an
average flow rate of 37.9 L/min during the demonstration.
2.3 Evaluation Approach
Evaluation of the bioreactor treatment technology occurred
between November 2003 and July 2005 on a year round basis.
During the evaluation period, multiple sampling events of the
treatment system were conducted in accordance with the 2003
Technology Evaluation Plan/Quality Assurance Project Plan
(TEP/QAPP) (Tetra Tech EM Inc [Terra Tech] 2003). During
each sampling event, EPA collected chemical data from the
systems' influent and effluent streams, documented metals
removal and reduction in acidity within the systems' unit
operations, and recorded operational information pertinent to
the evaluation of the treatment system. The treatment system
was evaluated based on removal efficiencies for primary and
secondary target metals, comparison of effluent concentrations
to EPA interim discharge standards, and on the characteristics
of and disposal requirements for the resulting metals-enriched
solid wastes. Removal efficiencies of individual unit
operations were also evaluated. The following sections
describe in more detail the project objectives and sampling
program.
2.3.1 Project Objectives
As discussed in the TEP/QAPP (Tetra Tech 2003), two
primary objectives identified for the SITE demonstration were
considered critical to the success of the bioreactor treatment
technology evaluation. Seven secondary objectives were
identified to provide additional information that is useful, but
not critical to the technology evaluation. The primary
objectives of the technology evaluations were to:
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• Determine the removal efficiencies for primary target
metals over the evaluation period
• Determine if the concentrations of the primary target
metals in the treated effluent are below the interim
(pre-risk assessment and record of decision)
discharge standards mandated in 2002 Action
Memorandum for Early Actions at Leviathan Mine
(EPA 2002)
The following secondary objectives also were identified:
• Document operating parameters and assess critical
operating conditions necessary to optimize system
performance
• Monitor the general chemical characteristics of the
ARD water as it passes through the treatment system
• Evaluate operational performance and efficiency of
solids separation systems
• Document solids transfer, dewatering, and disposal
operations
• Determine capital and operation and maintenance
(O&M) costs
• Document winter operating procedures and
effectiveness
• Determine the volume and type of metal precipitate
generated in the bioreactors and the optimal
frequency and duration of bioreactor flushing
2.3.2 Sampling Program
Over the duration of the demonstration, EPA collected
pretreatment, process, and post-treatment water samples from
the treatment system. These samples were used to evaluate
the primary and secondary objectives, as identified in the
TEP/QAPP (Tetra Tech 2003). Sludge samples also were
collected to document the physical and chemical
characteristics of the sludge and to estimate the volume and
rate of sludge generation. Summary tables documenting the
water and sludge samples collected and the analyses
performed for each mode of treatment system operation are
presented in Appendix A. In addition to chemical analyses
performed on the samples collected, observations were
recorded on many aspects of the operations of each treatment
system. The sampling program is summarized below by
objective.
Primary Objective 1: Determine the removal efficiency
for each metal of concern over the demonstration period.
To achieve this objective, influent and effluent samples from
the treatment system were collected from strategic locations
within the treatment system. The samples were filtered,
preserved, and then analyzed for primary target metals:
aluminum, arsenic, copper, iron, and nickel and secondary
water quality indicator metals: cadmium, chromium, lead,
selenium, and zinc. From the influent and effluent data
collected, overall average removal efficiencies were calculated
for each target metal over the period of the demonstration.
The results of the removal efficiency calculations are
summarized in Section 2.5.1.
Primary Objective 2: Determine if the concentration of
each target metal in the treated effluent is below the EPA
interim discharge standard. Results from effluent samples
collected to meet Primary Objective 1 were used to meet this
objective. The sampling schedule was designed so that a
composite of three grab samples were collected on each
sampling day. Results from daily composite samples were
compared against EPA's daily maximum discharge standards
(EPA 2002). In addition, 4-day running averages were
calculated for each target metal for comparison against EPA's
four-day average discharge standards. To determine if the
discharge standards were met, the effluent data were compared
directly to the applicable standards as specified in Table 2-1.
In addition, a statistical analysis was performed to determine
whether or not statistically the results were below the
discharge standards. The results of the comparison of effluent
data to discharge standards are summarized in Section 2.5.2.
Secondary Objective 1: Document operating parameters
and assess critical operating conditions necessary to
optimize system performance. To achieve this objective,
system flow and recirculation rate data, ethanol and sodium
hydroxide dosing data, and HRT data were recorded by the
system operator and the SITE demonstration sampling team.
The performance of individual unit operations was assessed by
determining the reduction in target metal concentrations along
the treatment system flow path. A description of system
operating parameters and discussion of metals reduction
within individual unit operations are presented in
Section 2.5.3.
Secondary Objective 2: Monitor the general chemical
characteristics of the ARD water as it passes through the
treatment system. To achieve this objective, the influent and
effluent samples collected to meet Primary Objectives 1 and 2
were analyzed for total iron, sulfate, total suspended solids
(TSS), total dissolved solids (TDS), and total and bicarbonate
alkalinity. Field measurements were also collected for ferrous
iron, sulfide, pH, dissolved oxygen (DO), temperature,
oxidation-reduction potential (ORP), and conductivity.
Organic analysis for residual ethanol or metabolites was not
conducted as a part of the sampling program. A discussion of
these data and associated reaction chemistry are presented in
Section 2.5.3.
Secondary Objective 3: Evaluate operational performance
and efficiency of solids separation systems. To achieve this
objective, influent and effluent samples were collected from
the bioreactors and settling ponds and were analyzed for
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filtered and unfiltered metals, TSS, and TDS to assess target
metal removal efficiencies, solids removal rates and
efficiencies, HRT, and residual levels of solids in the effluent
streams. The results of this evaluation are presented in
Section 2.5.3.
Secondary Objective 4: Document solids transfer,
dewatering, and disposal operations. To achieve this
objective, the system operator maintained a log of the volume
and rate of solids transferred from the settling ponds for
dewatering and disposal. Solids samples were collected after
dewatering and analyzed for residual moisture content and
total and leachable metals to determine waste characteristics
necessary for waste classification prior to disposal. Leachable
metals were evaluated using the California Waste Extraction
Test (WET) (State of California 2004), the Method 1311:
Toxicity Characteristic Leaching Procedure (TCLP) (EPA
1997), and Method 1312: Synthetic Precipitation and
Leaching Procedure (SPLP) (EPA 1997). An evaluation of
solids handling is presented in Section 2.5.4.
Secondary Objective 6: Document winter operating
procedures and effectiveness. To achieve this objective,
winter O&M activities were documented by the system
operator. The system operator logged changes to system
configuration; changes in influent flow and chemical dosing
rates; changes in activity of sulfate-reducing bacteria; changes
in solids settling efficiencies; operational problems and system
down time; frequency of site visits and access difficulties; and
consumables and equipment change out. Samples were also
collected as specified in secondary objective No. 1, 2, 3, and 4
to document the effect of winter conditions on the anaerobic
wetland treatment system. The results of this evaluation are
presented in Section 2.5.3.
Secondary Objective SAW1: Determine the volume and
type of metal precipitate generated in the bioreactors and
the optimal frequency and duration of bioreactor flushing.
To achieve this objective, the system operator documented the
volume of metal precipitate flushed from each bioreactor and
the overall rate and volume of metal precipitate accumulation
in the flushing pond. Solids samples were collected from the
flushing pond and analyzed for total metals to determine the
type of metal precipitates formed. An evaluation of solids
handling is presented in Sections 2.5.3 and 2.5.4.
2.4 Field Evaluation Activities
The following sections discuss activities required to conduct a
technical evaluation of each mode of the bioreactor treatment
system operation at the Leviathan Mine site. The discussion
includes a summary of mobilization activities, O&M
activities, process modifications, evaluation monitoring
activities, demobilization activities, and lessons learned.
2.4.1 Mobilization A ctivities
The bioreactor treatment system was constructed between the
fall of 2002 and the summer of 2003 and required startup and
acclimation prior to technology evaluation activities.
Mobilization activities described below were based on weekly
oversight visits under a separate contract and on information
provided by UNR. Mobilization activities after initial system
construction, including bioreactor acclimation, typically
require a two to three month period and include the following:
• Delivery, positioning, and assembly of reagent
storage tanks, reagent day tanks, reagent delivery
pumps, reagent metering devices, and distribution
lines
• Reagent delivery and storage
• Installation of solar panel and storage battery, layout
of power lines for reagent delivery pumps (gravity
flow operations)
• Initial filling of the bioreactors and one settling pond
• Monitoring of system influent, whole bioreactor
influent and effluent, individual bioreactor effluent
loops, and settling pond effluent for biological
activity, sulfide generation, metals removal
• Adjustment of ethanol and sodium hydroxide dosage
along with gradual increase in influent flow as
biological activity increases
• Pipe and pump lay out and assembly for recirculation
operations (recirculation flow operations)
• Fuel storage tank and secondary containment system
delivery, setup, and fuel delivery (recirculation flow
operations)
• Generator delivery and setup, layout of power lines
for recirculation pumps (recirculation flow
operations)
2.4.2 Operation and Maintenance Activities
The following section discusses O&M activities documented
during the evaluation of each mode of bioreactor treatment
operation. The discussion includes a summary of system
operational dates, treatment and discharge rates, problems
encountered, quantity of waste treated, reagents consumed,
process waste generated, and percentage of time the system
was operational.
The bioreactor treatment system was operated in gravity flow
mode from November 2003 through mid-May 2004, and in
recirculation mode from mid-May 2004 through July 2005. A
description of system O&M activities for each mode of
operation is presented below.
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Gravity Flow Operations. Bioreactor No.l began receiving
ARD during the first week on March 2003. On April 21, 2003
12 L/min of neutralized ARD (pH 8) and 700 mg/L ethanol
was diverted into Bioreactor No.l to begin the acclimation
process. On May 30, 2003, the flow of neutralized ARD (pH
6 to 7) was reduced to 4 to 6 L/min. On June 24, 2003
effluent from Bioreactor No.l was allowed to discharge to and
begin acclimation of Bioreactor No.2. Between August 12
and October 22, 2003 influent ARD flow was slowly
increased until the entire flow of Aspen Seep was being
treated. Acclimation of the bioreactors was completed on
November 12, 2003 at which point discharge from the
treatment system was initiated. Following acclimation,
treatment system discharge rates ranged from 25 to 47 L/min.
On November 13, 2003, the sodium hydroxide supply was
consumed and base addition at the influent weir was
suspended for one day pending delivery of sodium hydroxide.
Influent pH to the bioreactor was not adjusted; however, given
the long bioreactor HRT no impact was observed.
From November 25 through December 8, 2003, sodium
hydroxide addition to system ARD influent was deliberately
stopped to determine whether the bioreactors could treat the
ARD without an initial pH adjustment. Starting on December
8, 2003 sodium hydroxide was added to the effluent from
Bioreactor No.2 to raise the pH to near neutral in order to
promote the precipitation of iron sulfide in the settling pond.
During the week of December 22, 2003 the solar system
controller failure leading to a lack of base addition for up to
three days. The cessation of sodium hydroxide addition
reduced the pH in the pretreatment pond and Bioreactor No. 1.
Treatment of ARD from Aspen Seep under gravity flow
conditions was completed on May 11, 2004. During gravity
flow operations from November 12, 2003 through May 11,
2004, the system treated 9.24 million liters of ARD using
9,235 L of 25 percent sodium hydroxide (average dosage of
317 mg/L) and 4,466 L of ethanol (average dosage of 381
mg/L) and generated about 4.2 dry tons (3,800 kg) of non-
hazardous solids. The system was operational approximately
98 percent of the time during gravity flow operations. The
system operated 24 hours per day and was maintained 1 to 2
days per week by an operator.
Recirculation Flow Operations. Treatment of ARD from
Aspen Seep under recirculation flow conditions was initiated
on May 12, 2004 and continued through the end of the
technology evaluation period on July 13, 2005. Treatment
rates ranged from 25 to 91 L/min. Recirculation rates from
the settling pond to the head of Bioreactor No.l ranged from
114 to 227 L/min. On average, approximately five parts
sulfide-rich bioreactor effluent were mixed with one part
influent ARD in the settling pond.
Twice during the week of July 12, 2004 the generator supply
power for the recirculation pumps failed. Recirculation
stopped and sulfide-rich water was not longer discharging
from the bioreactors for up to two days. Influent ARD was
treated by residual sulfide in the settling pond and the flushing
pond.
On August 19, 2004, UNR reversed the flow direction in
Bioreactor No.l to minimize development of preferential flow
paths. Influent enters the north end of the bioreactor and
effluent discharges from the south end of the bioreactor.
Effluent is piped around the bioreactor and enters Bioreactor
No.2 in the typical south to north flow regime.
During the weeks of September 27 and October 4, 2004 sludge
was transferred from Pond 3 to Pond 4 to provide the
necessary sludge storage capacity in Pond 3 for winter
operations.
Twice during the week of November 8, 2004 the generator
supply power for the recirculation pumps failed due to water
in the diesel fuel tank. Recirculation stopped and sulfide-rich
water was not longer discharging from the bioreactors for up
to two days. The solar panel battery also failed, which
stopped the addition of sodium hydroxide to the settling pond
for up to three days. The cessation of sodium hydroxide
addition reduced the pH in the settling and flushing ponds.
Influent ARD was being treated by residual sulfide in the
settling pond and the flushing pond.
On November 25, 2004, the single large capacity recirculation
pump was replaced with three smaller capacity pumps to
provide redundancy in the event of a single pump failure. On
December 3, 2004 the intakes on the three recirculation pumps
were raised to reduce the intake of settled sludge from the
settling pond and transfer of solids to the head of Bioreactor
No.l. On February 3, 2005 the three smaller capacity pumps
were replaced with a single large capacity recirculation pump
due to reliability problems with the pump controller.
On March 17, 2005 the generator supply power for the
recirculation pump failed. Recirculation stopped and sulfide-
rich water was not longer discharging from the bioreactors for
up to two days. Influent ARD was being treated by residual
sulfide in the settling pond and the flushing pond.
During the week of June 28, 2005 settled solids were
transferred from the settling pond to the flushing pond.
On July 13, 2005 the generator supply power for the
recirculation pump failed. Recirculation stopped and sulfide-
rich water was not longer discharging from the bioreactors for
a one day period. Influent ARD was being treated by residual
sulfide in the settling pond and the flushing pond.
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On July 13, 2005 two solar powered recirculation pumps were
installed at the settling pond. The combined flow of the two
pumps was about 45 L/min, handling approximately one-
quarter of the flow necessary for recirculation operations.
On August 30, 2005 the generator supply power for the
recirculation pump failed. Recirculation stopped and sulfide-
rich water was not longer discharging from the bioreactors for
three days. Influent ARD was being treated by residual
sulfide in the settling pond and the flushing pond.
From mid-August through mid-November 2005,
approximately 200,000 L of sludge from the settling pond was
dewatered using seven bag filters. Each bag required one day
to build up a sufficient layer of cake to adequately concentrate
solids within the bag. Approximately 4.3 dry tons (3,900 kg)
of non-hazardous bag filter solids were generated and
disposed of off-site. Approximately 10 dry tons (9,100 kg) of
non-hazardous solids remain in the settling and flushing
ponds.
During recirculation flow operations, the system treated 22.1
million liters of ARD using 22,029 L of 25 percent sodium
hydroxide (average dosage of 316 mg/L) and 10,617 L of
ethanol (average dosage of 379 mg/L) and generated about 10
dry tons (9,100 kg) of non-hazardous solids. The system was
operational approximately 98 percent of the time during
recirculation operations. The system operated 24 hours per
day and was maintained 1 to 2 days per week by an operator.
2.4.3 Process Modifications
A number of modifications were made to the bioreactor
treatment system to improve bioreactor performance, solids
handling, and the type and rate of reagent consumption. The
primary modification involved recirculation as an alternate
mode of contact between ARD and sulfide-rich water and
location for collection of metal sulfide precipitates.
• An alternate method and location of contact between
the ARD and sulfide-rich bioreactor effluent was
implemented. Influent ARD was combined with
bioreactor effluent at the head of the settling pond to
promote precipitation and settling of metal sulfides in
the pond rather than in the individual bioreactors. A
portion of the sulfate-rich and metal-poor effluent
from the settling pond was recirculated to the head of
the two bioreactors for generation of additional
sulfide. The new configuration places less stress on
the sulfate-reducing bacteria through reduced metals
toxicity, higher influent pH, a more stable flow, and
greatly reduces the need to flush solids from the
bioreactors.
• Operation of the treatment system in the recirculation
configuration eliminated the need for the
pretreatment pond for initial pH adjustment and the
long term requirement to periodically flush solids
from the pond.
• Sodium hydroxide was demonstrated during
operation of the pilot-scale treatment system as the
preferred method of base addition. During the
evaluation of the full-scale treatment system,
alternative sources for addition of base were
evaluated. Sodium carbonate, sodium acetate,
potassium acetate, and syn-rock were evaluated and
were found to provide inadequate base delivery due
to large dose required, poor solubility, freezing, or
sealing of the reagent surface.
• During the evaluation of the full-scale treatment
system, alternative locations for addition of base
were evaluated. Adjustment of influent pH to
approximately 4.0 was found to be necessary prior to
bioreactor treatment to reduce stress on the sulfate-
reducing bacteria. Addition of base prior to the
settling pond to a neutral pH showed an improvement
in metals removal.
• In order to provide an opportunity for extended
contact of sulfides and metals and extended settling
of metal sulfides, the flushing pond was brought on
line to receive effluent from the settling pond,
effectively doubling settling time.
• Rather than setup and periodically pump settled
solids through bag filters for dewatering, settled
solids from the pretreatment pond and settling pond
were discharged to the flushing pond. Settled solids
were allowed to accumulate in the flushing pond
prior to bag filtration in the fall.
2.4.4 Evaluation Monitoring Activities
This section discusses monitoring activities conducted during
the evaluation of each mode of treatment technology
operation. The discussion includes a summary of sampling
dates and locations for system performance, unit operations,
solids handling, and solids disposal samples outlined in the
sampling program (see Section 2.3.2). Summary tables
documenting the water, sludge, and solids samples collected
and the analyses performed for each mode of treatment system
operation are presented in Appendix A.
The bioreactor treatment system was operated in the gravity
flow mode from November 2003 through mid-May 2004, and
in recirculation mode from mid-May 2004 through July 2005.
A description of evaluation monitoring activities for each
mode of operation is presented below.
Gravity Flow Evaluation Monitoring Activities. Both
system performance and unit operations sampling was
performed in 2003 and 2004. System performance and unit
operations samples were collected from the system influent
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and effluent on November 14 and 25, 2003; and January 29,
February 19, March 24, and April 29, 2004. No solids
samples were collected during gravity flow monitoring
activities as the settling ponds were just beginning to fill with
metal sulfide precipitates.
Recirculation Evaluation Monitoring Activities. Both
system performance and unit operations sampling was
performed in 2004 and 2005. System performance and unit
operations samples were collected from the system influent
and effluent on June 16, August 19, and December 3, 2004;
and February 3, March 17, April 27, and June 2, 2005.
A settling pond sample was collected on June 14, 2004.
Pretreatment pond, settling pond, flushing pond, and aeration
channel sludge samples were collected on July 13, 2005. A
composite sample of dewatered bag filter solids was collected
on September 29, 2005 for waste characterization.
2.4.5 Demobilization Activities
The bioreactor treatment system has been permanently
constructed at Leviathan Mine and operates on a year round
basis. Therefore, no demobilization activities were observed.
However, activities associated with preparation for winter
conditions were observed and documented.
Winterization activities observed for the bioreactor treatment
system include:
• Filling reagent and fuel tanks prior to build up of
snow pack
• Inspect and replace reagent delivery lines as
necessary
• Perform solar cell and battery maintenance
• Perform generator maintenance (replacement or
overhaul)
• Remove solids from settling ponds to provide
sufficient pond capacity for the winter
• Ship accumulated bag filter solids to an off-site non-
hazardous waste landfill or dispose of on-site.
• Lower level on pond decant structures to allow extra
precipitation capacity in settling/flushing ponds
• Clear decant structures of debris
• Remove portable toilets
2.4.6 Lessons Learned
This section discusses the lessons learned during the technical
evaluation of the bioreactor treatment system. The discussion
includes observations, recommendations, and ideas to be
implemented during future operations and for similar
treatment systems.
Lessons learned during the operation of bioreactor treatment
system include:
• Gravity flow operation of the bioreactor treatment
system allows precipitation and accumulation of
metal sulfides within the bioreactor. The
recirculation mode of operation evaluated at
Leviathan Mine promoted the generation of sulfide in
the bioreactors and the majority of metal sulfide
precipitation in the settling pond rather than in the
individual bioreactors. In addition, less stress was
placed on the sulfate-reducing bacteria by reducing
metals loading, operating at a higher influent pH, and
reducing frequency of solids flushing from the
bioreactors.
• Adjustment of influent pH to approximately 4.0 was
found to be necessary prior to bioreactor treatment to
reduce stress on the sulfate-reducing bacteria.
Addition of base prior to the settling pond to a neutral
pH showed an improvement in metals removal.
• Sodium hydroxide was demonstrated during
operation of the pilot-scale and full-scale treatment
system as the preferred method of base addition.
Other source materials were found to be inadequate
due to large dose required, poor solubility, freezing,
or sealing of the reagent surface.
• Health and safety issues observed during the
technology evaluation include skin and eye splash
contact when working with sodium hydroxide;
accumulation of hydrogen sulfide gas in depressions
and valve vaults; and slip hazards around the
perimeter of the settling and flushing ponds.
Mitigation of hazards associated with sodium
hydroxide includes arm length chemical gloves,
chemical apron, eye protection, and a face shield.
Mitigation of hazards associated with hydrogen
sulfide gas includes the use of gas detection meters
and blowers. Mitigation of slips hazards around the
settling and flushing ponds should include perimeter
fencing, barriers around open ponds, and a safety
rope when working inside the fenced area.
• During periods of high flow, base delivery upsets,
recirculation upsets, and extra pond capacity may be
required to provide sufficient HRT for precipitate
settling due to formation of smaller particles. At
Leviathan Mine, the flushing pond was brought on
line to receive effluent from the settling pond,
effectively doubling settling time.
• Sludge should be periodically transferred to the
flushing pond to provide adequate settling capacity in
the pretreatment and settling ponds.
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• Rather than setup and continuously pump settled
solids through bag filters for dewatering, settled
solids should be allowed to accumulate in the
flushing pond prior to periodic bag filtration.
• Bag filters may limit operations during freezing
temperatures in due to icing of the filter fabric, which
will create backpressure within the system.
Therefore, bag filtration of sludge should occur from
late spring through early fall.
2.5 Technology Evaluation Results
This section summarizes the evaluation of the metals data
collected during the SITE demonstration with respect to
meeting project objectives. Attainment of project primary
objectives is described in Sections 2.5.1 and 2.5.2, while
secondary objectives are provided in Section 2.5.3. Solids
handling and disposal for is discussed in Section 2.5.4.
Preliminary evaluation of the influent, effluent, and 4-day
average effluent metals data included an assessment of data
characteristics through quantitative and graphical analysis.
Influent, effluent, and 4-day average effluent concentrations
for the 10 metals of interest for each mode of treatment system
operation are presented in Tables B-l through B-2 of
Appendix B. Summary statistics calculated for these data sets
include: mean, median, standard deviation, and coefficient of
variation, which are presented in Tables B-3 through B-4 of
Appendix B. Minimum and maximum concentrations are also
presented.
Summary statistics for influent, effluent, and 4-day average
effluent data were determined using Analyze-It Excel
(Analyze-It 2004) and ProUCL (EPA 2004) statistical
software. In addition, frequency, box-and-whisker, and
probability plots were prepared to identify data characteristics
and relationships, evaluate data fit to a distribution (for
example, normal or lognormal), and to identify anomalous
data points or outliers for the 10 target metals for each of
treatment system operation. The results of statistical plotting
showed only one significant outlier in the effluent dataset for
iron. The iron effluent outlier was the result of inadequate
sodium hydroxide addition prior to the settling pond.
Summary statistics were prepared for the iron effluent data set
both with and without the outlier for comparative purposes.
No significant outliers were identified in the effluent data for
the other target metals. No significant outliers were identified
in the influent or 4-day average effluent datasets. No data
were rejected from the data sets. The statistical plots also
showed the metals influent and effluent concentrations to be
normally distributed, with the exception of those samples at or
near method detection limits. Statistical plots are documented
in the Technology Evaluation Report Data Summary (Tetra
Tech 2006).
2.5.1 Primary Objective No. 1: Evaluation of
Metals Removal Efficiencies
The evaluation of the bioreactor treatment system focused on
two primary objectives. The first objective was to determine
the removal efficiencies for the primary metals of concern and
the secondary water quality indicator metals. To successfully
calculate removal efficiencies for each metal, influent
concentrations must be significantly different than effluent
concentrations. Based on preliminary statistical plots
described in Section 2.5, the influent and effluent metals data
sets were found to be normally distributed; therefore a paired
Student's-t test (as described in EPA guidance [EPA 2000])
was used to determine if the influent and effluent
concentrations were statistically different. For this statistical
evaluation, if the P-value (test statistic) was less than the 0.05
significance level (or 95 percent confidence level), then the
two data sets were considered statistically different. Influent
and effluent concentrations for up to 7 of the 10 metals from
each bioreactor treatment system mode of operation were
found to be statistically different (P-value was less than 0.05),
and for these metals, removal efficiencies were calculated.
Tables 2-2 through 2-3 present the average and range of
removal efficiencies for filtered influent and effluent samples
collected during each mode of treatment system operation
during the SITE demonstration and also the P-value for the
paired Student's-t test analysis. The average influent and
effluent metals concentrations for each treatment system are
also presented. Where influent and effluent concentrations for
a particular metal were not statistically different (P-value was
greater than 0.05), removal efficiencies were not calculated for
that metal, as indicated in the summary tables. In addition,
where one or both concentrations for a metal were not
detected in an individual influent/effluent data pair, those data
points were not included in the determination of removal
efficiencies.
For the gravity flow mode of treatment system operation, the
average removal efficiency for the primary target metals was
94 percent over 6 sampling events. For the recirculation mode
of treatment system operation, the average removal efficiency
for the primary target metals was 96 percent over 7 sampling
events. Removal efficiencies for arsenic were not calculated
because the influent and effluent metals concentrations were
not statistically different. In addition, the concentration of
arsenic in system influent was well below discharge standards.
Average removal efficiencies for secondary target metals
ranged from 41 to 99 percent in both modes of operation;
however, removal efficiencies were not calculated for
chromium, lead, and selenium during gravity flow operations
as the influent and effluent concentrations were not
statistically different. Similarly, removal efficiencies were not
calculated for cadmium and selenium during recirculation
operations. In the case of arsenic, cadmium, chromium, and
lead in the ARD, concentrations were near or below the EPA
20
-------
Table 2-2. Removal Efficiencies for the Bioreactor Treatment System - Gravity Flow Operation
Target Metal
Number of
Sampling
Events
Average
Filtered Influent
Concentration
Gig/L)
Average Filtered
Effluent
Concentration
Oig/L)
Paired
Student' s-t test
P-value1
Average
Removal
Efficiency <2)
(%)
Range of Removal
Efficiencies (%)
Primary Target Metals
Aluminum
Arsenic
Copper
Iron
Nickel
6
6
6
6
6
37,467
2.1
691
117,167
487
103
4.7
4.8
4,885
65.5
<0.05
0.192
<0.05
<0.05
<0.05
99.7
NC
99.3
95.8
86.6
99.5 to 99.9
NC
99.1 to 99.7
65.6 to 99.9
72.1 to 92.6
Secondary Water Quality Indicator Metals
Cadmium
Chromium
Lead
Selenium
Zinc
6
6
6
6
6
0.61
12.2
3.6
13.9
715
<0.21
7.8
4.7
11.2
15.8
0.009
0.126
0.386
0.149
<0.05
65.3
NC
NC
NC
97.8
42. 5 to 79
NC
NC
NC
95.9 to 98.6
(1) A P-value less than 0.05 indicates that influent and effluent data are statistically different
(2) Average removal efficiency calculated using the average influent and average effluent concentration data
ug/L = Microgram per liter
% = Percent
NC = Not calculated as influent and effluent concentrations were not statistically different
Table 2-3. Removal Efficiencies for the Bioreactor Treatment System - Recirculation Operation
Target Metal
Number of
Sampling
Events
Average
Filtered Influent
Concentration
Gig/L)
Average Filtered
Effluent
Concentration
GM5/L)
Paired
Student' s-t test
P-value1
Average
Removal
Efficiency <2)
(%)
Range of Removal
Efficiencies (%)
Primary Target Metals
Aluminum
Arsenic
Copper
Iron
Nickel
7
7
7
7
7
40,029
7.4
795
115,785
529
52.7
6.5
4.6
2,704
69.7
<0.05
0.785
<0.05
<0.05
<0.05
99.9
NC
99.4
97.7
86.8
99.7 to 99.9
NC
98.8 to 99.8
92.8 to 99.7
71.0 to 96.4
Secondary Water Quality Indicator Metals
Cadmium
Chromium
Lead
Selenium
Zinc
7
7
7
7
7
0.60
11.1
4.2
11.5
776
<0.20
6.4
2.5
8.5
8.9
0.083
0.002
0.003
0.057
<0.05
NC
42.5
41.3
NC
98.9
NC
21.2 to 84.8
22.0 to 57.1
NC
97.7 to 99.8
(1) A P-value less than 0.05 indicates that influent and effluent data are statistically different
(2) Average removal efficiency calculated using the average influent and average effluent concentration data
ug/L = micrograms per liter
% = Percent
NC = Not calculated as influent and effluent concentrations were not statistically different
21
-------
interim discharge standards in the influent; therefore, the
treatment system was not optimized for removal of these
metals resulting in lower removal efficiencies. Removal
efficiencies for sulfate ranged from 8 to 35 percent with an
average reduction in sulfate of 17 percent. There was on
average a 9 percent increase in sulfate removal during the
recirculation mode of treatment system operation.
2.5.2 Primary Objective No. 2: Comparison of
Effluent Data to Discharge Standards
The second primary objective was to determine whether the
concentrations of the primary metals of concern in the effluent
from the two modes of bioreactor treatment system operation
were below EPA interim (pre-risk assessment and record of
decision) discharge standards, as presented in Table 2-4. The
4-day average discharge standard was originally intended for
comparison to the average of four-consecutive-day sampling
data. Instead, the average concentrations from four
consecutive sampling events were compared against the four-
day discharge standards. In addition, the attainment of
discharge standards for the secondary water quality parameters
was evaluated. Direct comparisons of the effluent data to the
maximum and 4-day average discharge standards show that
iron concentrations exceeded both sets of discharge standards,
and that lead and selenium exceeded their respective 4-day
average discharge standards. Additional statistical tests were
used to evaluate whether any other metals concentrations in
the effluent streams were statistically different from either set
of discharge standards.
Based on statistical plots described in Section 2.5, the metals
effluent and 4-day average effluent concentrations were shown
to be normally distributed; therefore, the one-sample
parametric Student's-t test (as described in EPA guidance
[EPA 2000]) was used in the comparison of the metals
concentrations to the discharge standards. The one- sample
parametric Student's-t test was used to determine if metals
effluent and 4-day average effluent concentrations were
significantly greater than the discharge standards (alternative
or Ha hypothesis). The maximum daily discharge standards,
maximum detected effluent concentrations, and average
effluent concentrations are summarized in Table 2-5 and the 4-
day average discharge standards and 4-day average effluent
concentrations are summarized in Table 2-6.
Based on preliminary statistical plots described in Section 2.5,
the metals effluent and 4-day average effluent concentrations
were shown to be normally distributed; therefore, the one-
sample parametric Student's-t test (as described in EPA
guidance [EPA 2000]) was used in the comparison of the
metals concentrations to the discharge standards. The one-
sample parametric Student's-t test was used to determine if
metals effluent and 4-day average effluent concentrations were
significantly greater than the discharge standards (alternative
or Ha hypothesis). The maximum daily discharge standards,
maximum detected effluent concentrations, and average
effluent concentrations are summarized in Table 2-5 and the 4-
day average discharge standards and 4-day average effluent
concentrations are summarized in Table 2-6.
Table 2-4. EPA Interim Discharge Standards
Target Metals
Maximum (a)
(Hg/L)
Average (b)
(fig/L)
Primary Target Metals
Aluminum
Arsenic
Copper
Iron
Nickel
4,000
340
26
2,000
840
2,000
150
16
1,000
94
Secondary Water Quality Indicator Metals
Cadmium
Chromium
Lead
Selenium
Zinc
9.0
970
136
No Standard
210
4.0
310
5.0
5.0
210
(a) Based on a daily composite of three grab samples
(b) Based on the average of four consecutive daily composite samples
ug/L = micrograms per liter
For the metals data sets that could be analyzed, the 1-tailed P-
values (test statistic) for all of the tests were above the 0.95
significance level (or 95 percent confidence level) required for
acceptance of the alternative hypothesis with the exception of
iron, lead, and selenium. Iron and selenium concentrations
were consistently above discharge standards, while only one
lead effluent sample was above discharge standards and
contributed to an elevated 4-day average concentration. There
is no maximum daily discharge standard for selenium;
therefore, there are no statistical results for selenium in Table
2-5. In addition, cadmium was not detected in any of the
effluent samples collected during either mode of treatment
system operation; therefore, there are no statistical results for
cadmium in either Table 2-5 or 2-6.
The compost-free bioreactor treatment system was shown to
be extremely effective at neutralizing acidity and reducing the
concentrations of the 4 of the 5 target metals to below EPA
interim discharge standards. Internal trials run to refine base
addition requirements and to evaluate various sources of base
addition lead to significant excursions of effluent iron
concentrations above the EPA interim discharge standards
during a portion of the evaluation period. However, after base
optimization during gravity flow operations effluent iron
concentrations met discharge standards. Iron also exceeded
discharge standards during recirculation operations when base
addition was stopped due to equipment failure or lack of
adequate base supply. Although the influent concentrations
22
-------
Table 2-5. Results of the Student's-t Test Statistical Analysis for Maximum Daily Effluent Data
Analyte
Maximum Daily
Discharge Limit
(«£/L)
Maximum Detected
Concentration in
Effluent Stream
(Hg/L)
Average
Concentration in
Effluent Stream
(Hg/L)
1-Tailed P-value
(Effluent Data >
Maximum Daily
Discharge Limit)
Effluent Concentration
Significantly Greater
than Maximum Daily
Discharge Limit?
(Hg/L)
Bioreactor Treatment System- Gravity Flow Mode Student's-t test Comparisons
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
4,000
340
9
970
26
2,000
136
840
No Standard
210
160
12.5
<0.32
16.3
6.5
39,200
9.8
125
13.9
29
103
4.7
<0.21
7.8
4.8
4,597
4.7
65.5
11.2
15.8
1.0
1.0
NC
1.0
1.0
0.107
1.0
1.0
Not Tested
1.0
No
No
No
No
No
Yes
No
No
Not Tested
No
Bioreactor Treatment System- Recirculation Mode Student's-t test Comparisons
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
4,000
340
9
970
26
2,000
136
840
No Standard
210
105
11.2
<0.3
14.1
9.5
9,060
4.6
154
12.3
18.8
52.7
6.51
<0.20
6.4
4.6
2,704
2.5
69.7
8.5
8.9
1.0
1.0
NC
1.0
1.0
0.279
1.0
1.0
Not Tested
1.0
No
No
No
No
No
Yes
No
No
Not Tested
No
ug/L = micrograms per liter
A P-value greater than 0.95 indicates that effluent data are not greater than the discharge standard
NC = Not calculated as sample results indicate metal was not detected
for the primary target metals were up to 580 fold above the
EPA interim discharge standards, the treatment system was
successful in reducing the concentrations of the primary target
metals in the ARD to between 1 and 43 fold below the
discharge standards. In addition, the concentrations of the
secondary target metals, with the exception of selenium, were
reduced to below the discharge standards.
2.5.3 Secondary Objectives for Evaluation of
Bioreactor Treatment System Unit
Operations
The evaluation of the bioreactor treatment system at Leviathan
Mine also included evaluation of four secondary objectives.
These secondary objectives included:
• Documentation of operating parameters and
assessment of critical operating conditions necessary
to optimize system performance.
• Monitoring the general chemical characteristics of
the ARD water as it passes through the treatment
system.
• Evaluating operational performance and efficiency of
solids separation systems.
• Documenting solids transfer, dewatering, and
disposal operations.
• Documentation of winter operating procedures and
effectiveness
• Determining the volume and type of metal precipitate
generated in the bioreactors and the optimal
frequency and duration of bioreactor flushing
Documentation of year round operating conditions, discussion
of reaction chemistry, evaluation of year round metals removal
by unit operation, and evaluation of solids flushing and
separation are presented in the following sections. The data
presented were compiled from observations during the
demonstration as well as data summarized in the Data
Summary Report for Bioreactors at the Leviathan Mine Aspen
Seep 2003 (Tsukamoto 2004), and the Data Summary Report
for Bioreactors at the Leviathan Mine Aspen Seep 2004
(Tsukamoto 2005a). Solids characterization and handling is
documented in Section 2.5.4.
23
-------
Table 2-6. Results of the Student's-t Test Statistical Analysis for 4-Day Average Effluent Data
Analyte
4-Day Average
Discharge Limit
(«£/L)
Maximum
4-Day Average (1)
Concentration in
Effluent Stream
(Hg/L)
Average
4-Day Average (1)
Concentration in
Effluent Stream
(Hg/L)
1-Tailed P-value
(Effluent Data >
Maximum Daily
Discharge Limit)
Effluent Concentration
Significantly Greater
than Maximum Daily
Discharge Limit?
(Hg/L)
Bioreactor Treatment System- Gravity Flow Mode Student's-t test Comparisons
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
2,000
150
4
310
16
1,000
5
94
5
210
128
5.2
<0.22
6.8
5.6
15,783
5.8
78.7
11.2
18.2
108
3.6
<0.21
5.8
4.8
14,118
5.5
68.1
10.7
14.9
1.0
1.0
NC
1.0
1.0
0.005
0.096
0.980
0.002
1.0
No
No
No
No
No
Yes
Yes
No
Yes
No
Bioreactor Treatment System- Recirculation Mode Student's-t test Comparisons
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
2,000
150
4
310
16
1,000
5
94
5
210
58.3
7.6
<0.21
7.4
5.1
3,760
2.4
85.8
9.8
8.0
52.1
5.3
<0.18
5.0
3.9
2,951
2
73
8.4
7.4
1.0
1.0
NC
1.0
1.0
0.012
1.0
0.991
0.004
1.0
No
No
No
No
No
Yes
No
No
Yes
No
(1) The data from four consecutive sampling events were used in the calculation of the average instead of four consecutive days
ug/L = micrograms per liter
A P-value greater than 0.95 indicates that effluent data are not greater than the discharge standard
NC = Not calculated as sample results indicate metal was not detected
2.5.3.1 Operating Conditions
Operating conditions for the bioreactor treatment system in
gravity flow and recirculation modes of operation are
described below.
Gravity Flow Operations. Operation of the treatment system
in gravity flow mode (Figure 1-2) involved the collection of
ARD from Aspen Seep in a rock-filled basin that was covered
with soil to limit entrainment of oxygen. Minimization of
dissolved oxygen in the influent ARD maximizes the
efficiency of surf ate-reducing bacteria within the bioreactors.
ARD discharges from the collection basin through a flow
measurement weir at an average flow rate of 31.8L/min.
After passing through the weir, influent ARD discharges into a
flow distribution box where 25 percent sodium hydroxide is
dripped into the flow at an average dosage rate of 8.3 ml/min
(83 mg/L) to reduce acidity and raise the pH of the ARD to
approximately 4.0 which reduces the stress on the sulfate-
reducing bacteria in the downstream bioreactors. Ethanol is
also dripped into the flow at an average dosage rate of 13.7
ml/min (340 mg/L) to provide a carbon source for the sulfate-
reducing bacteria in the downstream bioreactors. The sodium
hydroxide and ethanol are mixed into the ARD by turbulent
discharge from the distribution box to a pretreatment pond. A
small quantity of iron is typically precipitated out of solution
and is retained in the pretreatment pond. However, the
primary purpose of the pretreatment pond is to provide a flow
equalization buffer for influent to the bioreactors. The
average HRT of the pretreatment pond is 14.7 hours. Solids
are flushed from the pretreatment pond approximately once a
month, transferring from 2,000 to 7,OOOL of solids slurry to
the flushing pond during warm weather conditions. More
frequent flushing in winter is necessary due to limited
operational volume when the pond ices over. A summary of
the system operational parameters is presented in Table 2-7.
The ARD then flows by gravity into the first bioreactor.
Influent flow to both bioreactors is controlled through the use
of standpipes, rather than valves. The standpipes control flow
by manipulation of the energy grade line across each
bioreactor. Influent flow can be added to either end of each
bioreactor and can be targeted to the bottom, middle, or top of
each bioreactor to minimize the development of preferential
24
-------
Table 2-7. Gravity Flow Unit Operations Parameters
Parameter
System Influent Flow Rate
Influent Ethanol Dosage Rate
Influent NaOH Dosage Rate
Pretreatment Pond Settling Time
Bioreactor No. 1 Reaction Time
Bioreactor No. 2 Reaction Time
Pre-Settling Pond NaOH Dosage Rate
Settling Pond Residence Time
Flushing Pond Residence Time
Aeration Channel Residence Time
System Effluent Flow Rate
System Hydraulic Residence Time
Units
(L/min)
(ml/min)
(ml/min)
(hr)
(hr)
(hr)
(ml/min)
(hr)
(hr)
(min)
(L/min)
(hr)
Range
25 to 47
10.8 to 20.2
6.5 to 12.2
9.9 to 18.7
53. 2 to 100
30.1 to 56.7
21.3 to 40
165 to 310
181 to 340
29.8 to 56
25 to 47
440 to 826
Average
31.8
13.7
8.3
14.7
78.6
44.6
27
244
267
44
31.8
650
hr = hour min = Minute
L/min = Liter per minute ml/min = Milliliter per minute
flow paths. After sulfate reduction and precipitation of a
moderate quantity of metal sulfide solids in the first bioreactor
and generation of alkalinity through biological processes,
effluent discharges to the second bioreactor for reduction of
residual sulfate to sulfide and generation of additional
alkalinity. Similar to influent flow, effluent flow from each
bioreactor can be drawn from either end of each bioreactor
and can be removed from the bottom, middle, or top of each
bioreactor to minimize the development of preferential flow
paths. Buildup of excess metal sulfide solids within either
bioreactor can be drawn downward into flushing loops at the
bottom of each bioreactor. The flushing loops are controlled
by valves on a large flushing line that passes under the entire
length of the treatment system and discharges to a flushing
pond downstream of the pretreatment pond, the bioreactors,
and the settling pond. The bioreactors were flushed about
every two months during gravity flow operations, transferring
an estimated 15,000 L of solids slurry to the flushing pond.
The HRT of Bioreactor No.l averages 78.6 hours, while the
HRT of Bioreactor No.2 averages 44.6 hours at an average
influent flow rate of 31.8 L/min.
After passing through the two bioreactors, partially treated
ARD is dosed with sodium hydroxide and discharges to a
settling pond to allow extended time (244 hour average HRT)
for metal precipitation and settling. Twenty-five percent
sodium hydroxide solution is added to the settling pond
influent line at an average dosage rate of 27 ml/min (270
mg/L) to neutralize remaining acidity and raise the pH from
about pH 5 to a near neutral condition (pH 7) necessary for
precipitation of iron sulfide. The long HRT also allows
settling of metal precipitates and degassing of carbon dioxide
and hydrogen sulfide from solution, which reduces acidity and
raises solution pH. Effluent from the settling pond can be
discharged to a rock-lined aeration channel or to the flushing
pond for additional extended precipitate settling time. In
practice, effluent from the settling pond was always
discharged to the flushing pond for additional settling (267
hour average HRT) due to elevated paniculate iron
concentrations. Effluent from the flushing pond discharges to
the rock-lined aeration channel to promote gas exchange and
raise the ORP of the effluent. The aeration process promotes
precipitation of additional metals that react with excess
oxygen in solution. The average HRT for the system operated
in gravity flow mode is 650 hours at an average flow rate of
31.8 L/min. System HRT is extended to 827 hours in winter
when influent flows from Aspen Seep drop to 25 L/min. The
extended HRT provides adequate treatment during periods of
decreased biological activity, even at water temperatures of
1°C (degree Celsius). However, during the winter adequate
base addition is necessary to convert all of the bisulfide
generated in the bioreactors to sulfide necessary for iron
sulfide precipitation. Lack of or inadequate base addition
during the winter often leads to inability to meet iron
discharge standards.
Approximately 32,000 L of solids slurry is transferred from
the settling pond to the flushing pond prior to the onset of
winter. Periodically, metal sulfide sludge is pumped out of the
settling and flushing ponds and into bag filters for passive
dewatering prior to disposal as a nonhazardous solid. The
filtration process involves the filling of a bag filter with sludge
and gravity drainage of water through the filter fabric. Free
water is allowed to drain back into the flushing pond
following filtration. The process is repeated using a new bag
filter placed on top of an older bag. Additional solids
dewatering occurs in the bags on the bottom of the stack due
to compression. The process generated approximately 3,900
kilogram (kg) of dry solids over 100 days. The bag filtration
process is limited to summer and early fall when temperatures
are warm enough to prevent freezing of the filter membrane.
Recirculation Operations. The treatment system operated in
recirculation mode (Figure 1-3) utilizes the same processes as
the system operated in gravity flow mode; however, the metal-
rich ARD influent bypasses the pretreatment pond and the two
bioreactors and is combined with sulfide-rich bioreactor
effluent and sodium hydroxide and introduced to the settling
pond for metal sulfide precipitation. The key to recirculation
is the precipitation of metal sulfides in the settling pond rather
than in the two bioreactors, which reduces the need for and
frequency of bioreactor flushing and provides a stable sulfate-
reducing bacteria population within the bioreactors.
A portion of the sulfate-rich settling pond effluent containing
residual concentrations of metals is recirculated at an average
flow rate of 210 L/min to the head of Bioreactor No.l and
combined with ethanol to promote the generation of additional
sulfide. Ethanol is dripped into recirculated flow at the head
of Bioreactor No.l at an average dosage rate of 105 ml/min
(394 mg/L) to provide a carbon source for the surf ate-reducing
bacteria in the downstream bioreactors. The recirculated
settling pond effluent then flows by gravity through the two
bioreactors. After sulfate reduction, precipitation of metal
sulfides, and generation of alkalinity through biological
processes in both bioreactors, effluent is combined with ARD
influent at an average flow rate of 34.2 L/min and 25 percent
25
-------
sodium hydroxide solution at an average dosage rate of 17.1
ml/min (159 mg/L) and discharges to the settling pond. The
sodium hydroxide along with excess alkalinity in the
bioreactor effluent neutralizes acidity and raises the ARD
influent pH from about pH 3 to a near neutral condition (pH 7)
necessary for precipitation of iron sulfide. The bioreactors
were flushed every three to four months during recirculation
operations, transferring an estimated 15,000 L of solids to the
flushing pond. The HRT of Bioreactor No.l averages 11.9
hours, while the HRT of Bioreactor No.2 averages 6.8 hours at
an average recirculation flow rate of 210 L/min. A summary
of the system operational parameters is presented in Table 2-8.
Table 2-8. Recirculation Unit Operations Parameters
Parameter
System Influent Flow Rate
Bypass to Settling Pond
Recirculation from Settling Pond to
Bioreactor No.l
Influent Ethanol Dosage Rate
Bioreactor No. 1 Reaction Time
Bioreactor No. 2 Reaction Time
Pre-Settling Pond NaOH Dosage Rate
Settling Pond Residence Time
Settling Pond Discharge Rate
Flushing Pond Residence Time
Aeration Channel Residence Time
System Effluent Flow Rate
System Hydraulic Residence Time
Units
(L/min)
(L/min)
(L/min)
(ml/min)
(hr)
(hr)
(ml/min)
(hr)
(L/min)
(hr)
(min)
(L/min)
(hr)
Range
25 to 91
25 to 91
189 to 227
94.5 to 113.5
11 to 13.2
6.3 to 7.5
12.5 to 45.5
28.5 to 30.8
25 to 91
103 to 354
17 to 56
25 to 91
149 to 407
Average
34.2
34.2
210
105
11.9
6.8
17.1
29.7
34.1
249
41
34.1
298
hr = hour min = Minute
L/min = Liter per minute ml/min = Milliliter per minute
The settling pond allows extended time (29.7 hour average
HRT empty) for metal sulfide precipitation and settling. The
settling pond does not completely freeze over during winter
due to the circulation of water within the pond. Effluent (34.2
L/min) from the settling pond was always discharged to the
flushing pond for additional settling (249 hour average HRT)
due to elevated residual iron concentrations. The long HRT
also allows settling of metal precipitates and degassing of
carbon dioxide and hydrogen sulfide from solution, which
reduces acidity and raises solution pH. During recirculation
upsets the ORP increases and metal hydroxides precipitate,
which results in a pH decrease in the settling pond.
Approximately 48,000 L of solids slurry is transferred from
the settling pond to the flushing pond prior to the onset of
winter. Periodically, metal sulfide sludge is pumped out of the
settling and flushing ponds and into a bag filter for passive
dewatering prior to disposal as a nonhazardous solid.
Effluent from the flushing pond is discharged to the rock-lined
aeration channel to promote gas exchange, raise solution ORP,
and precipitate residual metals from solution. The average
HRT for the system operated in recirculation mode is 298
hours at an average flow rate of 34.2 L/min. System HRT is
extended to 408 hours in winter when influent flows from
Aspen Seep drop to 25 L/min. Adequate treatment is provided
during winter, even at relatively short bioreactor HRT and
very low water temperatures, due to the limited stress (neutral
pH and low metals concentrations) placed on the bioreactors.
However, adequate base addition is necessary to convert all of
the bisulfide generated in the bioreactors to sulfide for iron
sulfide precipitation in the settling pond. Lack of or
inadequate base addition during the winter can stress the
bioreactors resulting in reduce sulfide generation and an
overall inability to meet iron discharge standards.
2.5.3.2 Reaction Chemistry
The reaction chemistry for the bioreactor treatment system is
described below for both the gravity flow and recirculation
modes of operation. A warm weather date for the gravity flow
mode of operation was not available as the system was
converted to recirculation operations in May 2004. Instead, a
cold weather date (March 24, 2004) was selected for gravity
flow mode of operation and a warm weather date (August 19,
2004) was selected for recirculation mode to evaluate potential
impact of cold weather on system effectiveness.
Gravity Flow Reaction Chemistry. Changes in ARD
chemistry within the pretreatment pond are driven by the
addition of sodium hydroxide to the influent ARD at the
influent weir box. Sodium hydroxide addition consumes
mineral acidity, raises solution pH, increases the kinetics of
iron oxidation, and provides a source of hydroxide ion for
ferric hydroxide formation. A small quantity of iron
precipitate formed, a portion of which is deposited in the
pond.
During the pretreatment process, solution pH increased from
3.1 to 3.6 after sodium hydroxide addition and target metals
decreased 28 percent (primarily aluminum at 7 percent, iron at
35 percent) in response to excess hydroxide ion. The data also
indicate that mineral acidity was reduced as evidenced by an
increase in pH and a decrease in solution ORP. Field and
analytical laboratory chemical parameters documenting
reaction chemistry on March 24, 2004 are provided in Table
2-9.
Supernatant from the pretreatment pond discharges to the head
of Bioreactor No.l, where it is combined with ethanol to
provide a carbon substrate for the sulfate-reducing bacteria.
Observed changes in ARD chemistry in the effluent from the
two bioreactors were primarily due to the reduction of sulfate
to sulfide by sulfate-reducing bacteria and the generation of
acetate associated with incomplete oxidation of ethanol and
alkalinity during the complete oxidation of ethanol to carbon
dioxide. Sulfide combines with excess metals to form metal
sulfide precipitates. Alkalinity raises the pH of ARD in the
bioreactors and facilitates precipitation reactions. However,
the pH is not high enough to convert bisulfide to sulfide and
precipitate the majority of the iron as iron sulfide; therefore
the majority of the iron and bisulfide pass out of the two
bioreactors.
26
-------
Table 2-9. Gravity Flow Unit Operation Reaction Chemistry
Parameter
PH
Oxidation Reduction Potential
Total Iron (dissolved)
Specific Conductance
Dissolved Oxygen
Temperature
Sulfate
Sulfide
Total Alkalinity
Total Dissolved Solids
Unit
(SU)
(mV)
(mg/L)
(nmhos/cm)
(mg/L)
(°C)
(mg/L)
(mg/L)
(mg/L)
(mg/L)
Pretreatment Pond
Influent
3.1
425
113
2,368
3.3
12.4
1,510
0
<2
2,200
Effluent
3.6
324
73.1
2,335
6.8
12.4
1,520
0
<2
2,240
Change
0.5
-101
-39.9
-33
3.6
0
10
0
0
40
Bioreactor No.l
Influent
3.6
324
73.1
2,335
6.8
12.4
1,520
0
<2
2,240
Effluent
4.7
-117
71.7
2,166
6.1
11.5
1,480
37
<2
2,380
Change
1.1
-441
-1.4
-169
-0.7
-0.9
-40
37
0
140
Bioreactor No.2
Influent
4.7
-117
71.7
2,166
6.1
11.5
1,480
37
<2
2,380
Effluent
4.8
-122
63.7
1,989
6.4
11.3
1,310
38
<2
2,090
Change
0.1
-5
-8
-177
0.3
-0.2
-170
1
0
-290
Hmhos/cm = Micromhos per centimeter mV = Millivolt NC = Not calculated
°C = Degree Celsius mg/L = Milligram per liter SU = Standard unit
Data collected on March 24, 2004 at a system Influent and effluent flow rate of 45 L/min
Parameter
pH
Oxidation Reduction Potential
Total Iron (dissolved)
Specific Conductance
Dissolved Oxygen
Temperature
Sulfate
Sulfide
Total Alkalinity
Total Dissolved Solids
Unit
(SU)
(mV)
(mg/L)
(ixmhos/cm)
(mg/L)
(°C)
(mg/L)
(mg/L)
(mg/L)
(mg/L)
Settling and Flushing Ponds
Influent
4.8
-122
63.7
1,989
6.4
11.3
1,310
38
<2
2,090
Effluent
7.5
91
0.19
2,235
8.6
12.6
1,170
0
113
1,900
Change
2.7
213
-63.5
246
2.2
1.3
-140
-38
113
-190
Aeration Channel
Influent
7.5
91
0.19
2,235
8.6
12.6
1,170
0
113
1,900
Effluent
7.7
40
0.39
2,181
8.8
12
1,160
0
110
1,720
Change
0.2
-51
0.2
-54
0.2
-0.6
-10
0
-20
-180
Hmhos/cm = Micromhos per centimeter mV = Millivolt SU = Standard unit
°C = Degree Celsius mg/L = Milligram per liter
Data collected on March 24, 2004 at a system influent and effluent flow rate of 45 L/min
Bioreactor No.l effluent pH increased from 3.6 to 4.7, ORP
shifted from highly oxidizing (+324 mV [millivolt]) to
moderately reducing (-117 mV), sulfate decreased from
1,520 to 1,480 mg/L, and 37 mg/L of excess sulfide was
generated. Target metals decreased 10 percent (primarily
aluminum at 24 percent, copper at 99 percent, nickel at 22
percent, and zinc at 95 percent). Divalent metals were
removed primarily by sulfide precipitation, while aluminum
was removed by hydroxide precipitation. The data also
indicate that mineral acidity was reduced as evidenced by an
increase in pH and a decrease in solution ORP. Bicarbonate
alkalinity was generated as solution pH increased by over
one standard unit, though excess alkalinity was not observed
in bioreactor effluent. Biological generation of bicarbonate
alkalinity reduces the sodium hydroxide dosage required.
Bioreactor No.2 effluent pH increased from 4.7 to 4.8, ORP
shifted to slightly more reducing (-117 to -122 mV), sulfate
decreased from 1,480 to 1,310 mg/L, and excess sulfide
generated increased slightly (37 to 38 mg/L). Target metals
decreased 12 percent (primarily aluminum at 15 percent,
iron at 11 percent, and nickel at 14 percent). Divalent
metals were removed primarily by sulfide precipitation,
while aluminum was removed by hydroxide precipitation.
The data indicate that mineral acidity continued to be
reduced. Bicarbonate alkalinity was generated as solution
pH continued to increase, though excess alkalinity was not
observed in bioreactor effluent. Organic analysis for
residual ethanol or metabolites was not conducted as a part
of the demonstration. However, the technology developer
has indicated that approximately one-third of the ethanol is
incompletely oxidized to acetate within the bioreactors
(Tsukamoto 2005b).
As a point of comparison, during cold weather conditions
(water temperature 5°C) on February 19, 2004, sulfate
decreased from 1,520 to 1,290 mg/L (15 percent) and total
iron decreased from 70 to 67 mg/L (5 percent) across the
bioreactors. A lack of adequate base addition was
responsible for elevated iron concentrations, rather than
insufficient sulfate reduction. Across the system as a whole,
both low temperature and high flow suppresses sulfate
reduction to sulfide and iron removal. The impact on
temperature on sulfate reduction and iron removal is
presented in Table 2-10.
27
-------
Table 2-10. Impact of Temperature on Sulfate Reduction
and Iron Removal During Gravity Flow Operations
Date
11/14/03
11/25/03
1/29/04
2/19/04
3/24/04
4/29/04
Temp
(°C)
4.8
4.5
3.8
5.2
10.9
10.1
Sulfate
Mass
Removed
(kg/day)
10.5
11.2
5.8
11.3
22.7
11.2
Sulfate
Removal
Efficiency
(%)
17.5
18.1
9.9
17.4
23.2
13.4
Iron
Mass
Removed
(kg/day)
4.4
4.3
2.9
4.2
7.2
6.6
Iron
Removal
Efficiency
(%)
95.8
89.6
63.1
93.7
98.5
99.7
Flow
(L/min)
26
26
29
29
45
39
% = Percent kg/day = Kilogram per day
°C = Degree Celsius L/min = Liter per minute
After partially-treated ARD passes out of Bioreactor No.2, the
effluent is combined with sodium hydroxide and discharged to
the settling pond. Sodium hydroxide addition consumes the
remaining mineral acidity, and converts a portion of the
bisulfide to sulfide, which is necessary to precipitate the
remaining iron as iron sulfide in the settling pond. Sodium
hydroxide also provides a source of hydroxide ion for metals
that do not form precipitates with sulfide. Excess sulfide from
bioreactor No.2 is generally completely consumed by metals
or is oxidized to sulfate during the extended settling pond
HRT.
The effluent pH from the flushing pond increased from 4.8 to
7.5, ORP shifted from moderately reducing (-122 mV) to
moderately oxidizing (+91 mV), and sulfate decreased from
1,310 to 1,170 mg/L. No excess sulfide was observed in the
flushing pond effluent, though sulfide may have been
generated by sulfate-reducing bacteria in the settling pond and
consumed in the flushing pond given the substantial decrease
in sulfate concentrations across the two ponds. Target metals
decreased 99.7 percent (primarily aluminum at 99.9 percent,
iron at 99.7 percent, nickel at 84 percent, and zinc at 87
percent). Divalent metals were removed primarily by sulfide
precipitation in the settling pond, while aluminum was
removed by metal hydroxide and oxyhydroxide precipitation
at a neutral pH condition. Additional metals removal in the
flushing pond was likely related to agglomeration of colloidal
metals and particle settling. The remaining mineral acidity
was completely consumed by excess sodium hydroxide in
solution, yielding a bicarbonate alkalinity of 113 mg/L.
After settling, treated ARD passes out of the flushing pond to
an aeration channel to introduce oxygen, off-gas carbon
dioxide, and precipitate residual metals from solution as metal
hydroxides. Effluent dissolved oxygen was 8.8 mg/L. The
effluent pH from the aeration channel increased from 7.5 to
7.7, ORP decreased from +91 to +40 mV, and sulfate
decreased slightly from 1,170 to 1,160 mg/L. No excess
sulfide was observed. All of the target metals except for
soluble chromium increased slightly. Excess alkalinity
decreased slightly, likely in response to residual metals
precipitating as metal hydroxides.
Recirculation Reaction Chemistry. Influent ARD is
combined with the effluent from Bioreactor No.2 and sodium
hydroxide to form precipitates in the settling pond. Settling
pond supernatant is at a near neutral pH and is slightly
reducing, containing residual metals, excess sulfate, and
excess bicarbonate alkalinity. A portion of the settling pond
supernatant is recirculated to the head of Bioreactor No.l,
where it is combined with ethanol to provide a carbon
substrate for the sulfate-reducing bacteria.
Observed changes in ARD chemistry in the effluent from the
two bioreactors were primarily due to the reduction of sulfate
to sulfide by sulfate-reducing bacteria and the generation of
acetate associated with incomplete oxidation of ethanol and
alkalinity during the complete oxidation of ethanol to carbon
dioxide. Sulfide combines with excess metals to form metal
sulfide precipitates. Because the partially-treated ARD in the
bioreactors is at a neutral pH condition, residual metals
actively precipitate in the bioreactors, while excess sulfides
pass out of the two bioreactors to the settling pond.
System influent ARD and the effluent from Bioreactor No.2
are combined at the head of the settling pond. On August 19,
2004, after combining the two ARD streams (8:1 dilution), pH
increased from 3 to 6.8, ORP decreased from 510 to -114 mV,
sulfate decreased from 1,630 to 1,156 mg/L, and sulfide
increased from 0 to 44 mg/L, and target metals decreased from
142 mg/L to 18 mg/L. Field and analytical laboratory
chemical parameters documenting reaction chemistry are
provided in Table 2-11.
After the two ARD streams are combined, chemistry is driven
by the addition of sodium hydroxide. Sodium hydroxide
addition consumes mineral acidity, and converts bisulfide to
sulfide, which is necessary to precipitate iron as iron sulfide.
Sodium hydroxide also provides a source of hydroxide ion for
ferric hydroxide precipitation, which occurs if the
recirculation system is nonfunctional.
During the contact of metal-rich influent ARD and sulfide-rich
Bioreactor No.2 effluent in the settling pond, combined
solution pH increased from 6.8 to 7.2 in the pond supernatant,
ORP shifted from moderately to slightly reducing (-117 to -27
mV), sulfate increased from 1,156 to 1,190 mg/L, and all of
the excess sulfide (44 mg/L) from the bioreactors was
oxidized or consumed. The data also indicate that mineral
acidity was reduced as evidenced by an increase in pH and a
decrease in solution ORP. Bicarbonate alkalinity decreased
from 233 to 210 mg/L after addition of acidic influent ARD.
Target metals decreased 71 percent across the settling pond
(primarily aluminum at 97 percent, copper at 92 percent, iron
at 61 percent, and zinc at 83 percent). Divalent metals were
removed primarily by sulfide precipitation, while aluminum
was removed by metal hydroxide and oxyhydroxide
precipitation at a neutral pH condition. Insufficient sulfide
was present in the settling pond to precipitate all of the metals
28
-------
Table 2-11. Recirculation Unit Operation Reaction Chemistry
Parameter
PH
Oxidation Reduction Potential
Total Iron (dissolved)
Specific Conductance
Dissolved Oxygen
Temperature
Sulfate
Sulfide
Total Alkalinity
Total Dissolved Solids
Unit
(SU)
(mV)
(mg/L)
(|jmhos/cm)
(mg/L)
(°C)
(mg/L)
(mg/L)
(mg/L)
(mg/L)
Bioreactor No.l
Influent
7.2
-27
4.9
2,595
1.9
19.4
1,190
0
210
2,090
Effluent
7.2
-174
0.26
2,569
0.3
20.1
1,160
27
209
2,060
Change
0
-147
-4.6
-26
-1.6
0.7
-30
27
-1
-30
Bioreactor No.2
Influent
7.2
-174
0.26
2,569
0.3
20.1
1,160
27
209
2,060
Effluent
7.3
-202
0.25
2,555
1.4
20.1
1,090
50
266
2,150
Change
0.1
-28
-0.01
-14
1.1
0
-70
23
57
90
System
Influent
3
510
99.5
2,572
1.6
16.7
1,630
0
<2
3,040
Combined
Influent
6.8
-114
12.5
2,557
1.4
19.7
1,156
43.8
233
2,260
|jmhos/cm = Micromhos per centimeter mV = Millivolt SU = Standard unit
°C = Degree Celsius mg/L = Milligram per liter
Data collected on August 19, 2004 at a system influent flow rate of 32 L/min, a recirculation rate of 227 L/mln, and a system effluent rate
of 28 L/mln
Parameter
PH
Oxidation Reduction Potential
Total Iron (dissolved)
Specific Conductance
Dissolved Oxygen
Temperature
Sulfate
Sulfide
Total Alkalinity
Total Dissolved Solids
Unit
(SU)
(mV)
(mg/L)
(|jmhos/cm)
(mg/L)
(°C)
(mg/L)
(mg/L)
(mg/L)
(mg/L)
Settling Pond
Combined
Influent
6.8
-114
12.5
2,557
1.4
19.7
1,156
44
233
2,260
Effluent
7.2
-27
4.9
2,595
1.9
19.4
1,190
0
210
2,090
Change
0.4
87
-7.6
38
0.48
-0.3
34
-44
-23
-170
Flushing Pond
Influent
7.2
-27
4.9
2,595
1.9
19.4
1,190
0
210
2,090
Effluent
7.6
103
0.1
2,674
4.1
21
1,260
0
208
2,160
Change
0.4
130
-4.8
79
2.2
1.6
70
0
-2
70
Aeration Channel
Influent
7.6
103
0.1
2,674
4.1
21
1,260
0
208
2,160
Effluent
7.6
10
0.27
2,660
2.1
21.3
1,200
0
202
2,140
Change
0
-93
0.17
-14
-2
0.3
-60
0
-6
-20
Hmhos/cm = Micromhos per centimeter mV = Millivolt NC = Not calculated
°C = Degree Celsius mg/L = Milligram per liter SU = Standard unit
Data collected on August 19, 2004 at a system influent flow rate of 32 L/min, a recirculation rate of 227 L/min,
and a system effluent rate of 28 L/min
out of solution. Recirculation of a portion of the settling pond
supernatant to the head of Bioreactor No.l provides an
opportunity to generate additional sulfide necessary to remove
residual metals (primarily iron) from solution.
After recirculation of a portion of the settling pond supernatant
to Bioreactor No. 1, the bioreactor effluent pH remained at 7.2,
ORP shifted from slightly to moderately reducing (-27 to -174
mV), sulfate decreased from 1,190 to 1,160 mg/L, and 27
mg/L of excess sulfide was generated. Target metals
decreased 92 percent across bioreactor No.l (primarily
aluminum at 33, iron at 95 percent, and nickel at 84 percent).
Divalent metals were removed primarily by sulfide
precipitation. All soluble metals concentrations were below
discharge standards. Bicarbonate alkalinity essentially
remained unchanged.
Bioreactor No.2 effluent pH increased slightly from 7.2 to 7.3,
ORP shifted to slightly more reducing (-174 to -202 mV),
sulfate decreased from 1,160 to 1,090 mg/L, and excess
sulfide generated doubled (27 to 50 mg/L). Target metals
concentrations remained essentially unchanged. Excess
sulfide generated in the bioreactor is combined with system
influent ARD as described above to precipitate metal sulfides
in the settling pond. Bicarbonate alkalinity increased from
209 to 266 mg/L due to biological oxidation of ethanol.
Organic analysis for residual ethanol or metabolites was not
conducted as a part of the demonstration. However, the
technology developer has indicated that approximately one-
third of the ethanol is incompletely oxidized to acetate within
the bioreactors (Tsukamoto 2005b).
As a point of comparison, during cold weather conditions
(water temperature 3°C) on December 3, 2004, sulfate
decreased from 1,310 to 1,300 mg/L (0.8 percent) and total
iron decreased from 10.1 to 7.0 mg/L (30.7 percent) across the
two bioreactors. Colder water temperature (3°C versus 20°C)
appears to slow sulfate reduction (0.8 versus 8 percent) as well
29
-------
as iron removal (30.7 versus 95 percent). A larger amount of
residual iron was recirculated from the settling pond to the
head of the bioreactors in response to less available sulfide
necessary for iron sulfide precipitation. Across the system as
a whole, both low temperature and high influent and
recirculation flows suppress sulfate reduction to sulfide and
iron removal. The impact on temperature on sulfate reduction
and iron removal is presented in Table 2-12.
Table 2-12. Impact of Temperature on Sulfate Reduction
and Iron Removal During Recirculation Operations
Date
6/14/04
8/19/04
12/3/04
2/3/05
3/17/05
4/24/05
6/2/05
Temp
(°C)
13.7
14.7
3.1
6.3
5.5
8.6
13.7
Sulfate
Mass
Removed
(kg/day)
7.3
19.8
7.9
10.8
21.9
33.5
15.6
Sulfate
Removal
Efficiency
(%)
7.6
26.4
12.5
19.7
35.3
18.5
8
Iron
Mass
Removed
(kg/day)
6
4.5
4.8
4.3
4.5
13.3
13.5
Iron
Removal
Efficiency
(%)
96.6
99.5
91.7
97.3
99.4
98.3
97.8
Flow
(L/min)
42
32
29
25
28
83
72
% = Percent kg/day = Kilogram per day
°C = Degree Celsius L/min = Liter per minute
A portion of the settling pond supernatant also discharges to
the flushing pond for extended settling. The effluent pH from
the flushing pond increased from 7.2 to 7.6, ORP shifted from
slightly reducing (-27 mV) to moderately oxidizing (+103
mV), and sulfate increased from 1,190 to 1,260 mg/L. The
increase in sulfate may be the result of the dissolution of
suspended colloidal material and oxidation of sulfide. Soluble
iron decreased by 98 percent from 4.9 to 0.1 mg/L likely in
response to agglomeration of colloidal iron and particle
settling. All other target metal concentrations, with the
exception of aluminum, nickel, and zinc increased slightly.
Bicarbonate alkalinity remained essentially unchanged at 208
mg/L.
After extended settling, treated ARD passes out of the flushing
pond to an aeration channel off-gas carbon dioxide, introduce
oxygen to the water, and precipitate residual metals from
solution. Effluent dissolved oxygen was 2.1 mg/L, which is
lower than observed during gravity flow operations. Low
dissolved oxygen was observed for about 3 months following
conversion to recirculation operations then increased to levels
observed during gravity flow operations. The effluent pH
from the aeration channel remained at about 7.6, ORP
decreased from +103 to +10 mV, and sulfate decreased from
1,260 to 1,200 mg/L. No excess sulfide was observed.
Soluble aluminum, iron, and arsenic increased slightly, while
all other target metals decreased slightly in response to metal
hydroxide precipitation at a neutral pH condition. Excess
alkalinity decreased slightly, likely in response to residual
metals precipitating as metal hydroxides.
2.5.3.3 Metals Removal by Unit Operation
Metals removal by each bioreactor unit operation is described
below for both the gravity flow mode (March 24, 2004) and
recirculation mode (August 19, 2004) of operation.
Gravity Flow Operations. Aluminum, copper, iron, lead,
nickel, selenium, and zinc are the metals of concern in the
ARD from Aspen Seep. All of the dissolved metals of
concern exceeded their discharge standards after sodium
hydroxide addition and initial settling in the pretreatment
pond. Pretreatment pond dissolved metals removal
efficiencies ranged from -48 to 35 percent, with the majority
of the mass removal associated with aluminum and iron oxides
and oxyhydroxides. No sulfate reduction occurred in the
pretreatment pond. A summary of unit operations
concentration and removal efficiency data for the dissolved
metals of concern is presented in Table 2-13 for gravity flow
unit operations on March 24, 2004.
Following about a 3 percent reduction in sulfate concentration
(40 mg/L) within Bioreactor No.l, the majority of the
dissolved metals of concern continued to exceed their
discharge standards, with the exception of copper and zinc,
which appear to have precipitated as metal sulfides from
solution. The concentration of aluminum and iron also
decreased substantially, but precipitation was limited by too
low of a pH in the bioreactor. Bioreactor No.l dissolved
metals removal efficiencies ranged from 2 to 99.1 percent,
with the majority of the mass removal associated with
aluminum, copper, iron, and zinc. Following an 12 percent
reduction in sulfate concentration (170 mg/L) within
Bioreactor No.2, the majority of dissolved metals of concern
continued to exceed their discharge standards, with the
exception of copper, lead, and zinc, which appear to have
continued to precipitate as metal sulfides from solution. The
concentration of aluminum and iron also continued to decrease
substantially. Bioreactor No.2 dissolved metals removal
efficiencies ranged from 10 to 15 percent, with the majority of
the mass removal associated with aluminum and iron.
Following sodium hydroxide addition to bioreactor effluent,
which raised the pH to near neutral condition, and additional
sulfide generation, metal sulfide precipitation, and solids
settling in the settling and flushing ponds, only selenium
exceeded its discharge standard, though not at a concentration
that was statistically significant. Settling and flushing pond
dissolved metals removal efficiencies ranged from 25 to 99.9
percent, with the majority of the mass removal associated with
aluminum and iron. Precipitation of aluminum and iron
required a near neutral pH condition.
All of the metals of concern, with the exception of selenium,
met discharge standards at the toe of the rock lined aeration
channel after hydrogen sulfide off-gassing and oxygen
30
-------
Table 2-13. Gravity Flow Unit Operation Dissolved Metals Removal Efficiencies
Parameter
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
Pretreatment Pond
Influent
(M8/L)
36,900
2.8
0.4
17.2
656
113,000
5.3
481
9.6
702
Effluent
(HB/L)
34,200
<2.3
<0.23
13.9
614
73,100
5.8
449
14.2
661
Removal
Efficiency
(%)
7.3
NC
NC
19.2
6.4
35.3
NC
6.7
-47.9
5.8
Bioreactor No.l
Effluent
(M8/L)
26,100
3
<0.23
13.3
5.7
71,700
5.8
350
10.8
32
Removal
Efficiency
(%)
23.7
NC
NC
4.3
99.1
1.9
NC
22.1
23.9
95.2
Bioreactor No.2
Effluent
(HS/L)
22,200
<2.3
<0.23
14.3
6.1
63,700
5
300
10.6
28.8
Removal
Efficiency
(%)
14.9
NC
NC
NC
NC
11.2
NC
14.3
NC
10.0
Settling and
Flushing Ponds
Effluent
(M8/L)
31.7
<2.3
<0.23
6.9
4.3
186
2.9
49.2
7.9
3.7
Removal
Efficiency
(%)
99.9
NC
NC
51.8
29.5
99.7
42.0
83.6
25.5
87.2
Aeration Channel
Effluent
(HS/L)
144
2.4
<0.23
6.4
5.6
389
3.4
53.1
8.7
10.3
Removal
Efficiency
(%)
-354
NC
NC
7.3
NC
-109
NC
-7.9
NC
-178
System
Removal
Efficiency
(%)
99.6
14.3
42.5
62.8
99.1
99.7
35.8
89
9.4
98.5
% = Percent NC = Not calculated as influent and effluent concentrations were not statistically different
|xg/L = Microgram per liter Data collected on March 24, 2004 at a flow rate of 45 L/min
Table 2-14. Gravity Flow Unit Operation Metals and Sulfate Load Reduction
Parameter
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
Target Metals
Total Metals (1)
Sulfate
Sulfide
Pretreatment Pond
Influent
(g/day)
2,391
0
0.027
1.06
41.9
7,322
0.32
31.0
0.79
44.8
9,801
38,350
97,850
0
Effluent
(g/day)
2,341
0.23
0.027
0.95
42.1
5,612
0.38
30.6
0.90
46.1
8,074
36,690
98,500
0
Mass
Change
(g/day)
-50
0.23
0
-0.11
0..2
-1,710
0.06
-0.34
0.11
1.21
-1,759
-1,660
650
0
Bioreactor No.l
Effluent
(g/day)
1,834
0
0
0.90
4.4
5,035
0.356
24.0
0.804
8.1
6,907
36,290
95,900
870
Mass
Change
(g/day)
-508
-0.23
-0.03
-0.05
-37.3
-577
-0.02
-6.7
-0.10
-37.9
-1,166
-400
-2,600
870
Bioreactor No.2
Effluent
(g/day)
1,471
0.22
0
0.83
3.5
4,128
0.29
19.4
0.64
6.0
5,630
31,085
84,890
3,670
Mass
Change
(g/day)
-363
0.22
0
-0.07
-0.90
-907
-0.07
-4.5
-0.16
-2.1
-1,278
-5,205
-11,010
2,800
Settling and
Flushing Ponds
Effluent
(g/day)
7.9
0
0
1.5
0.28
103.7
0.13
4.0
0.58
0.38
119
24,200
75,820
0
Mass
Change
(g/day)
-1,463
-0.22
0
0.67
-3.2
-4,204
-0.16
-15.4
-0.06
-5.6
-5,511
-6,885
-9,070
-3,670
Aeration Channel
Effluent
(g/day)
30.3
0.29
0
0.52
0.51
108
0.19
4.6
0.34
0.95
145
23,120
75,170
0
Mass
Change
(g/day)
22.4
0.29
0
-0.98
0.23
3.9
0.06
0.59
-0.24
0.57
26.8
-1,080
-650
0
(1) Total metals excluding added sodium from sodium hydroxide addition Data collected on March 24, 2004 at a flow rate of 45 L/min
g/day = gram per day
entrainment. Selenium exceeded its discharge standard,
though not at a concentration that was statistically significant.
Removal efficiencies for almost all of the dissolved metals
were negative, indicating that either suspended solids
discharged from the flushing pond were dissolving into
solution or that solids were being flushed out of the aeration
channel. Review of unfiltered channel influent and effluent
data indicate that solids were being actively flushed from the
channel during the sampling event. Treatment system removal
efficiencies for the dissolved metals of concern ranged from 9
percent for selenium to 99.7 percent for iron at a concurrent
sulfate removal efficiency of 23 percent.
An evaluation of target metals load reduction, sulfate load
reduction, and sulfide generation was prepared for gravity
flow operations based on unit operations data collected on
March 24, 2004 and is presented in Table 2-14. A total metals
load of 38.3 kg and a sulfate load of 97.9 kg entered the
bioreactor treatment system at 45 L/min. A total of 1.7 kg of
metals was precipitated out of solution, following the addition
of 4.1 kg of sodium hydroxide to the ARD in the pretreatment
pond, leaving 36.7 kg of metals (excluding sodium addition)
and 98.5 kg of sulfate in pretreatment pond effluent.
Sulfate-reducing bacteria in Bioreactor No.l removed 2.6 kg
of sulfate (generating 0.9 kg sulfide) and 0.4 kg of metals from
solution as a metal sulfide precipitate, leaving 36.3 kg of
metals (excluding sodium addition) and 95.9 kg of sulfate in
Bioreactor No.l effluent for further treatment in Bioreactor
No.2. An additional 5.2 kg of metals and 11 kg of sulfate
(generating 3.7 kg sulfide) were removed from solution as a
metal sulfide precipitate in Bioreactor No.2.
31
-------
A total of 31 kg of metals (excluding sodium addition) and
84.9 kg of sulfate were discharged from Bioreactor No.2 to the
settling and flushing ponds in conjunction with 11.9 kg of
sodium hydroxide for extended metal sulfide and metal oxide
and oxyhydroxide contact, precipitation, and settling,
removing 6.9 kg of metals and 9.1 kg of sulfate from solution.
A total of 24.2 kg of metals (excluding sodium addition) and
75.8 kg of sulfate were discharged from the settling and
flushing ponds to the rock lined aeration channel to entrain
oxygen and remove additional metals from solution as metal
hydroxides and oxyhydroxides. A total of 1.1 kg of metals
and 0.7 kg of sulfate were removed from solution along the
aeration channel. Overall, a total of 16 kg of sodium
hydroxide and 4.5 kg of sulfide were required to neutralize
acidity and precipitate 15.2 kg of total metals (9.7 kg of target
metals) from ARD.
Recirculation Operations. Aluminum, copper, iron, lead,
nickel, selenium, and zinc are the metals of concern in the
ARD from Aspen Seep. Iron and selenium were the only
dissolved metals of concern that exceeded their discharge
standards in the settling pond effluent after combining the
influent ARD, Bioreactor No.2 effluent, and sodium
hydroxide in the settling pond. Settling pond metals removal
efficiencies ranged from 3 to 97 percent, with the majority of
the mass removal associated with aluminum, copper, iron, and
zinc. No sulfate reduction occurred in the settling pond likely
due to the short HRT and biologically stressful pond
conditions. A summary of unit operations concentration and
removal efficiency data for the metals of concern is presented
in Table 2-15 for recirculation unit operations.
Following recirculation of a portion of the settling pond
effluent to the head of Bioreactor No.l, the sulfate-reducing
bacteria removed an additional 3 percent reduction of sulfate
from solution (30 mg/L). All of the dissolved metals of
concern were below their discharge standards, with the
exception of selenium. Bioreactor No.l metals removal
efficiencies ranged from -52 to 95 percent, with the majority
of the mass removal associated with aluminum, iron, and
nickel as the pH within the bioreactor was near neutral
condition. Following a 6 percent reduction in sulfate
concentration (70 mg/L) within Bioreactor No.2, all of the
dissolved metals of concern were below their discharge
standards, with the exception of selenium. Bioreactor No.2
metals removal efficiencies ranged from -65 to 13 percent.
There was no significant reduction in metals mass within
Bioreactor No.2. Instead, biological activity generated excess
sulfide in the bioreactor effluent for downstream blending
with ARD influent in the settling pond. Comparison of the
amount of sulfate reduced between the two modes of operation
is difficult because the flow rate through the bioreactors is up
to 8 times higher with recirculation. In fact, if the
recirculation rate was decreased slightly sulfate reduction
would exceed that of the gravity flow system due to the more
favorable environmental conditions (neutral pH and low
metals concentrations).
After initial precipitation in the settling pond, effluent was
held in the flushing pond to allow extended time for metal
sulfide precipitation and settling. Only selenium exceeded its
discharge standard, though not at a concentration that was
statistically significant. Sulfate-reducing bacteria did not
appear to be active in the flushing pond. Flushing pond metals
removal efficiencies ranged from -60 to 98 percent, with the
majority of the mass removal associated with aluminum, iron,
and nickel.
All of the metals of concern, with the exception of selenium,
met discharge standards at the toe of the rock lined aeration
channel following gas exchange. Selenium exceeded its
discharge standard, though not at a concentration that was
statistically significant. Removal efficiencies for aluminum,
arsenic, and iron were negative, indicating that suspended
solids or colloids discharged from the flushing pond were
dissolving into solution. The system as a whole removed from
40 to 99.7 percent of the target metals from solution.
Treatment system removal efficiencies for the metals of
concern ranged from 41 percent for arsenic to 99.7 percent for
iron at a concurrent sulfate removal efficiency of 26 percent.
An evaluation of target metals load reduction, sulfate load
reduction, and sulfide generation was prepared for
recirculation operations based on unit operations data
collected on August 19, 2004 and is presented in Table 2-16.
A total metals load of 28.2 kg and a sulfate load of 75.1 kg
entered the bioreactor treatment system at 32 L/min. The
influent ARD was blended with 152 kg of metals and 356 kg
of sulfate discharging from Bioreactor No.2 at 227 L/min.
The combined influent metals load of 180 kg and sulfate load
of 431 kg was blended with 5.8 kg of sodium hydroxide and
discharged to the settling pond at 259 L/min. A total of 4.1 kg
of metals was removed from solution and 12.4 kg of sulfate
entered solution (sulfide oxidation) in the settling pond,
leaving 176 kg of metals (excluding sodium addition) and 443
kg of sulfate in settling pond supernatant, a portion of which
was recirculated to the head of Bioreactor No.l at 227 L/min.
Sulfate-reducing bacteria in Bioreactor No.l removed 9.8 kg
of sulfate (generating 3.3 kg sulfide), leaving 379 kg of sulfate
in solution for further treatment in Bioreactor No.2.
Approximately 1.2 kg of metals was deposited in Bioreactor
No.l. An additional 1.2 kg of metals and 22.9 kg of sulfate
(generating 4.4 kg sulfide) were removed from solution as a
metal sulfide precipitate in Bioreactor No.2.
A portion of the settling pond supernatant containing 21.8 kg
of metals and 54.8 kg of sulfate was also discharged (32
L/min) to the flushing pond for extended metal sulfide
precipitation and settling, removing 2.3 kg of metals and 4 kg
of sulfate from solution. A total of 19.5 kg of metals
(excluding sodium addition) and 50.8 kg of sulfate were
discharged from the flushing pond to the rock lined aeration
channel to entrain oxygen and remove additional metals from
32
-------
Table 2-15. Recirculation Unit Operation Dissolved Metals Removal Efficiencies
Parameter
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
Bioreactor No.l
Effluent
(MS/L)
104
5.9
0.21
11.8
7.1
266
4.2
11.7
11.4
6.3
Removal
Efficiency
(%)
32.9
NC
40.0
NC
14.5
94.6
NC
83.9
-52.0
63.4
Bioreactor No.2
Effluent
(Mg/L)
108
5
0.41
12
7.6
247
4
10.2
11.6
10.4
Removal
Efficiency
(%)
NC
NC
NC
NC
NC
7.1
NC
12.8
NC
-65.1
Settling Pond
System
Influent
(Hg/L)
40,400
<2.1
0.94
19.3
766
99,500
5.9
531
14.4
755
Combined
Influent
(MS/L)
5,086
4.64
0.48
12.9
101.3
12,510
4.23
74.6
11.95
102.4
Effluent
(MS/L)
155
4.4
0.35
12.2
8.3
4,900
4.2
72.6
7.5
17.2
Removal
Efficiency
(%)
97.0
NC
26.4
5.4
91.8
60.8
NC
2.6
37.2
83.2
Flushing Pond
Effluent
(MS/L)
94.7
3.7
0.39
12.2
10
109
6.7
54.8
11.1
10.2
Removal
Efficiency
(%)
57.4
15.9
NC
NC
-20.5
97.8
-59.5
24.5
-48.0
40.7
Aeration Channel
Effluent
(Mg/L)
105
14.7
<0.16
11.6
9.5
269
3.1
18.9
7.8
4.5
Removal
Efficiency
(%)
-10.9
-297
59.0
4.9
NC
-147
53.7
65.5
29.7
55.9
System
Removal
Efficiency
(%)
99.7
-600
83.0
39.9
98.8
99.7
47.5
96.4
45.8
99.4
% = Percent NC = Not calculated as influent and effluent concentrations were not statistically different
Hg/L = Microgram per liter Data collected on August 19, 2004 at a system Influent flow rate of 32 L/min, a recirculation rate of
227 L/min, and a system effluent rate of 28 L/min
Table 2-16. Recirculation Unit Operation Metals and Sulfate Load Reduction
Parameter
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
Sum of Target
Metals
Total Metals (1)
Sulfate
Sulfide
Bioreactor No.l
Effluent
(g/day)
127
0
0
3.92
3.5
1,026
1.54
10.9
3.37
4.48
1,181
153,350
379,200
3,270
Mass
Change
(g/day)
-255
0
-0.08
0
-4.45
-1,566
0.13
-13.1
-0.69
-4.67
-1,844
1,160
-9,800
3,270
Bioreactor No.2
Effluent
(g/day)
109
0.85
0.08
3.82
3.73
879
1.24
9.35
2.91
4.77
1,015
152,140
356,300
7,640
Mass
Change
(g/day)
-18
0.85
0.08
-0.10
0.23
-147
-0.29
-1.57
-0.46
0.29
-166
-1,210
-22,900
4,370
Settling Pond
System
Influent
(g/day)
1,862
0
0.05
0.91
34.9
4,567
0.33
24.4
0.92
34.9
6,525
28,200
75,110
0
Combined
Influent
(g/day)
1,971
0.85
0.14
4.74
38.61
5,446
1.57
33.7
3.83
39.7
7,540
180,350
431,400
7,640
Pond (2)
Effluent
(g/day)
436
0
0.09
4.47
9.06
2,958
1.6
27.4
4.62
10.5
3,452
176,300
443,820
0
Mass
Change
(g/day)
-1,535
-0.85
-0.05
-0.27
-29.6
-2,488
0.03
-6.3
0.79
-29.2
-4,088
-4,050
12,420
-7,640
Flushing Pond
Influent
(g/day)
53.9
0
0.01
0.55
1.12
365
0.2
3.38
0.57
1.29
426.5
21,780
54,840
0
Effluent
(g/day)
6.9
0
0
0.48
0.47
41.5
0.16
2.15
0.38
1.25
53.4
19,450
50,800
0
Mass
Change
(g/day)
-47
0
-0.01
-0.07
-0.65
-324
-0.04
-1.23
-0.19
-0.04
-373
-2,330
-4,040
0
Aeration Channel
Effluent
(g/day)
4.8
0.6
0
0.53
0.32
21.5
0.26
0.9
0.44
0.43
29.8
20,150
48,380
0
Mass
Change
(g/day)
-2.1
0.6
0
0.05
-0.15
-20.1
0.1
-1.25
0.06
-0.82
-23.6
700
-2,420
0
(1) Total metals excluding added sodium from sodium hydroxide addition g/day = gram per day Recirc = Recirculation
(2) Settling pond effluent loads are split between recirculation and flushing pond influent
Data collected on August 19, 2004 at a system influent flow rate of 32 L/min, a recirculation rate of 227 L/min, and a system effluent rate of 28 L/min
solution as metal hydroxides and oxyhydroxides. A total of
2.4 kg of sulfate was removed from solution along the aeration
channel, while total metals mass increased by 0.7 kg due to
entrainment of metals along the aeration channel. Overall, a
total of 5.8 kg of sodium hydroxide and 7.6 kg of sulfide were
required to neutralize acidity and precipitate 8 kg of total
metals (6.5 kg of target metals) from ARD.
Operation of the treatment system in recirculation mode
required 49 percent less sodium hydroxide and reduced 41
percent more sulfate to sulfide than the treatment system
operated in gravity flow mode. Metals removal in each mode
of operation was similar.
2.5.3.4 Solids Separation
Solids separation techniques used during both the gravity flow
mode (March 24, 2004) and recirculation mode (August 19,
2004) of operation are described below.
Gravity Flow Operations. Precipitate generated during
operation of the bioreactor treatment system in gravity flow
mode is separated from ARD using a pretreatment pond,
bioreactor pore space, a settling pond, and a flushing pond.
Sodium hydroxide is used during the pretreatment process to
raise the influent pH to Bioreactor No.l to approximately
33
-------
Table 2-17. Gravity Flow Operation Solids Separation Efficiencies
Parameter
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
TSS
Pretreatment Pond
Unfiltered
Influent
(MS/L)
36,400
4.2
0.41
16.4
647
113,000
4.9
478
12.2
692
36,000
Unflltered
Effluent
(MS/L)
36,300
<2.2
0.42
14.7
653
87,000
5.9
475
14
714
87,000
Percent
Removal
(%)
0.3
47.6
-2.4
10.4
-0.9
23
-20.4
0.6
-14.8
-3.2
-142
Bioreactor No.l
Unflltered
Influent
(MS/L)
36,300
<2.2
0.42
14.7
653
87,000
5.9
475
14
714
87,000
Unflltered
Effluent
(HS/L)
28,300
<2.3
<0.23
13.9
67.6
77,700
5.5
370
12.4
125
9,000
Percent
Removal
(%)
22
-4.6
45.2
5.4
89.7
10.7
6.8
22.1
11.4
82.5
89.7
Bioreactor No.2
Unflltered
Influent
(MS/L)
28,300
<2.3
<0.23
13.9
67.6
77,700
5.5
370
12.4
125
9,000
Unflltered
Effluent
(MS/L)
22,700
3.4
<0.23
12.8
53.7
63,700
4.4
300
9.9
92.7
16,000
Percent
Removal
(%)
19.8
-47.8
0
7.9
20.6
18
20
18.9
20.2
25.8
-77.8
% = Percent Data collected on March 24, 2004 at a flow rate of 45 L/min
Lig/L = Microgram per liter
Parameter
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
TSS
Settling and Flushing Ponds
Unflltered
Influent
(MS/L)
22,700
3.4
<0.23
12.8
53.7
63,700
4.4
300
9.9
92.7
16,000
Unfiltered
Effluent
(MS/L)
122
<2.3
<0.23
23.2
4.3
1,600
2
62.4
8.9
5.9
6,000
Percent
Removal
(%)
99.5
32.4
0
-81.3
92
97.5
54.6
79.2
10.1
93.6
62.5
Aeration Channel
Unfiltered
Influent
(MS/L)
122
<2.3
<0.23
23.2
4.3
1,600
2
62.4
8.9
5.9
6,000
Unflltered
Effluent
(MS/L)
468
<2.2
<0.23
8
7.8
1,660
2.9
71.5
5.2
14.7
6,000
Percent
Removal
(%)
-284
4.4
0
65.5
-81.4
-3.8
-45
-14.6
41.6
-149
0
Cumulative
Percent
Removal
(%)
98.7
47.6
43.9
51.2
98.8
98.5
40.8
85
57.4
97.9
83.3
% = Percent Data collected on March 24, 2004 at a flow rate of 45 L/min
|xg/L = Microgram per liter
pH 4. Metal hydroxide and oxyhydroxide precipitate is
formed during the process, a portion of which settles within
the 10.3 hour pond HRT at a flow rate of 45 L/min.
Approximately 23 percent of the iron in the influent ARD
precipitated and settled in the pretreatment pond during this
process. An increase in TSS concentration in the pond
effluent indicates that an additional 11 percent of the iron
precipitate that was formed in the pretreatment pond was
passed out of the pond and into bioreactor No. 1. On average,
approximately 3.9 kg of settled solids are generated in the
pretreatment pond each day. From 2,000 to 7,OOOL of solids
are flushed out of the pretreatment pond to the flushing pond
approximately once a month. Settled solids are determined by
calculating the differences between influent and effluent
metals and anion concentrations for each unit operation,
identifying likely metal-anion pairs, and summing the masses
of metal-anion pairs that likely formed precipitates. Total
metals removal efficiencies for each unit operation are
provided in Table 2-17.
Metal sulfide precipitate is formed within the two bioreactors
as sulfate is converted to sulfide by sulfate-reducing bacteria.
Precipitate formation and settling within Bioreactor No.l
occurred over a 55.6 hour HRT. Metal sulfide precipitation
and settling in Bioreactor No.l provided an additional 5 to 90
percent removal of influent metals (primarily aluminum,
copper, iron, nickel, and zinc) from solution. An additional 2
percent of the aluminum, 10 percent of the copper, and 13
percent of the zinc precipitates that were formed in bioreactor
No.l were passed out of the bioreactor to bioreactor No.2.
However, the decrease in TSS concentration in the bioreactor
effluent, primarily related to iron precipitate, confirmed that
the majority of the solids were retained in the bioreactor.
Precipitate formation and settling within Bioreactor No.2
occurred over a 31.5 hour HRT. Metal sulfide precipitation
and settling in Bioreactor No.2 provided an additional 8 to 26
percent removal of influent metals (primarily aluminum,
copper, iron, nickel, and zinc) from solution. An additional 2
percent of the aluminum, 70 percent of the copper, and 66
34
-------
percent of the zinc precipitates that were formed in bioreactor
No.2 passed out of the bioreactor to the settling pond. The
slight increase in TSS concentration in the bioreactor effluent
confirmed that the majority of the solids were passed out of
the bioreactor. On average, approximately 1 kg of settled
solids are generated in Bioreactor No.l and 12 kg of settled
solids in Bioreactor No.2 each day. Every 2 months
approximately 15,000 L of solids are flushed out of the two
bioreactors to the flushing pond. Formation of sulfide
precipitates is limited by low solution pH (4 to 5.5); therefore,
the bulk of metal sulfide precipitate formation and settling
occurs downstream of the bioreactors in the settling pond,
after adjustment of effluent pH to a near neutral condition.
Maintaining a low pH in the bioreactors reduces the volume of
settled solids and the need for bioreactor flushing, which
places a stress on the sulfate-reducing bacteria.
Metals and sulfides in the Bioreactor No.2 effluent were
combined with sodium hydroxide to raise the pH to a neutral
condition, and discharged to the settling pond for the bulk of
precipitate formation and solids settling. Effluent from the
settling pond was discharged to the flushing pond for extended
settling. Metal sulfide, metal hydroxide, and metal
oxyhydroxide precipitate is formed during the process, which
is allowed to settle within the 172 hour settling pond HRT and
188.9 hour flushing pond HRT. Precipitate formation and
settling within the two ponds provided an additional 25.5 to
99.9 percent removal of influent metals (primarily aluminum,
copper, iron, nickel, and zinc) from solution. An additional
0.4 percent of the aluminum, 2.2 percent of the iron, and 4.4
percent of the nickel precipitates that were formed in the
flushing pond were passed out of the pond to the aeration
channel. The decrease in TSS concentration in the effluent
confirmed that solids were retained in the settling and flushing
ponds. Depth of accumulated solids within the two ponds
suggests that approximately 95 percent of the solids are
retained in the settling pond, with the other 5 percent of solids
retained in the flushing pond. On average, approximately 15.5
kg of settled solids are generated each day in the settling pond
and 0.8 kg of settled solids in the flushing pond. Prior to the
onset of winter, approximately 32,000 L of solids are
transferred out of the settling pond to the flushing pond to
maintain an adequate HRT necessary for solids settling.
The concentration of aluminum, copper, iron, lead, nickel, and
zinc increased slightly in aeration channel effluent. However,
TSS concentrations did not increase and effluent from the
aeration channel met EPA discharge criteria. On average,
approximately 2.5 kg of solids settle in the aeration channel
each day. Collectively, the treatment system generated 33.2
kg of solids each day. Settled solids are pumped out of the
flushing pond and settling pond and passed through bag filters
for dewatering each fall to provide adequate solids storage
capacity over the following winter. During the fall of 2005, a
bag filtration process was used to dewater settled solids
pumped out of the settling and flushing ponds prior to disposal
as a nonhazardous solid. The settled solids were generated by
both gravity flow and recirculation modes of operation. The
bag filtration process involved the filling of a bag filter with
settled solids, followed by gravity drainage of water through
the filter fabric for up to two weeks. Free water was allowed
to drain back into the flushing pond following filtration. The
process was repeated using a new bag filter placed on top of
an older bag. Additional solids dewatering occurred in the
bags on the bottom of the stack due to compression.
Approximately 200,000 L of settled solids from both modes of
operation were discharged to seven bag filters over 100 days
of solids dewatering, generating approximately 3,900 kg (4.3
dry tons) of solids in the fall of 2005. The bag filters removed
10 percent of the water from the settled solids and
concentrated metals by 120 percent. The bag filters remain on
site and are being allowed to air dry to further reduce moisture
content prior to disposal. The bag filtration process is limited
to summer and early fall when temperatures are warm enough
to prevent freezing of the filter membrane.
Recirculation Operations. Precipitate generated during
operation of the bioreactor treatment system in recirculation
mode is separated from ARD using a settling pond, bioreactor
pore space, and a flushing pond. Residual metals and excess
sulfide in Bioreactor No.2 effluent were combined with
influent ARD and sodium hydroxide to raise the pH to a
neutral condition, and discharged to the settling pond for the
bulk of precipitate formation and solids settling. A small
portion of the settling pond effluent was discharged to the
flushing pond, while the majority was recirculated to the head
of Bioreactor No.l for additional sulfide generation. Metal
sulfide, metal hydroxide, and metal oxyhydroxide precipitate
is formed in the pond, which is allowed to settle within the
29.9 hour settling pond HRT at a combined flow rate of 259
L/min. Precipitate formation and settling provided 6 to 78
percent removal of combined influent metals and 38 to 97
percent removal of system influent metals (primarily
aluminum, copper, iron, nickel, and zinc) from solution. An
additional 19.1 percent of the aluminum, 15.2 percent of the
copper, 15.1 percent of the iron, and 9.6 percent of the zinc
precipitates that were formed in the settling pond were passed
out of the pond to both the head of Bioreactor No.l and the
flushing pond for extended settling. The TSS concentration
increased in settling pond effluent, indicating that the HRT of
the pond was too short to allow adequate solids settling. On
average, approximately 9.9 kg of settled solids are generated
each day in the settling pond. Prior to the onset of winter,
approximately 48,000 L of solids are transferred out of the
settling pond to the flushing pond to maintain an adequate
HRT necessary for solids settling. Settled solids are
determined by calculating the differences between influent and
effluent metals and anion concentrations for each unit
operation, identifying likely metal-anion pairs, and summing
the masses of metal-anion pairs that likely formed precipitates.
Total metals removal efficiencies for each unit operation are
provided in Table 2-18.
35
-------
Table 2-18. Recirculation Operation Solids Separation Efficiencies
Parameter
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
TSS
Bioreactor No.l
Unflltered
Influent
(Hg/L)
1,170
<2.1
0.23
12
24.3
7,930
4.3
73.4
12.4
28
27,000
Unflltered
Effluent
(HB/L)
389
<2.1
<0.16
12
10.7
3,140
4.7
33.4
10.3
13.7
42,000
Percent
Removal
(%)
66.8
0
30.4
0
56
60.4
-9.3
54.5
16.9
51.1
-55.6
Bioreactor No.2
Unflltered
Influent
(Hg/L)
389
<2.1
<0.16
12
10.7
3,140
4.7
33.4
10.3
13.7
42,000
Unflltered
Effluent
(Hg/L)
334
2.6
0.26
11.7
11.4
2,690
3.8
28.6
8.9
14.6
7,000
Percent
Removal
(%)
14.1
-23.8
-62.5
2.5
-6.5
14.3
19.2
14.4
13.6
-6.6
83.3
Settling Pond
System
Unflltered
Influent
(Hg/L)
40,400
<2.1
1.1
19.8
757
99,100
7.2
529
19.9
757
<10,000
Combined
Unflltered
Influent
(Hg/L)
5,284
2.3
0.36
12.7
104
14,602
4.2
90.4
10.3
106
7,000
Unflltered
Effluent
(Hg/L)
1,170
<2.1
0.23
12
24.3
7,930
4.3
73.4
12.4
28
27,000
Percent
Removal
(%)
77.9
8.7
36.1
5.8
76.6
45.7
-2.4
18.8
-20.4
73.6
-286
% = Percent Data collected on August 19, 2004 at a system influent flow rate of 32 L/min,
|Jg/L = Microgram per liter a recirculation rate of 227 L/min, and a system effluent rate of 28 L/min.
Combined influent to the settling pond takes into account the mass of metals in the
influent ARD as well as the mass of metals in the effluent from bioreactor No.2.
Parameter
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
TSS
Flushing Pond
Unflltered
Influent
(Hg/L)
1,170
<2.1
0.23
12
24.3
7,930
4.3
73.4
12.4
28
27,000
Unflltered
Effluent
(Hg/L)
172
<2.1
<0.16
11.9
11.7
1,030
4
53.3
9.4
31
<10,000
Percent
Removal
(%)
85.3
0
30.4
0.8
51.9
87
7
27.4
24.2
-10.7
63
Aeration Channel
Unflltered
Influent
(Hg/L)
172
<2.1
<0.16
11.9
11.7
1,030
4
53.3
9.4
31
<10,000
Unflltered
Effluent
(Hg/L)
120
14.9
<0.16
13.2
7.9
532
6.5
22.4
10.8
10.6
<10,000
Percent
Removal
(%)
30.2
-609
0
-10.9
32.5
48.4
-62.5
58
-14.9
65.8
0
Cumulative
System
Percent
Removal
(%)
99.7
-548
85.5
33.3
99
99.5
9.7
95.8
45.7
98.6
0
% = Percent Data collected on August 19, 2004 at a system influent flow
|Jg/L = Microgram per liter rate of 32 L/min, a recirculation rate of 227 L/min, and a
system effluent rate of 28 L/min
A moderate quantity of metal sulfide precipitate is formed
within the two bioreactors as sulfate is converted to sulfide by
sulfate-reducing bacteria. Precipitate formation and settling
within Bioreactor No.l occurs over an 11.0 hour HRT at a
recirculation rate of 227 L/min. Metal sulfide precipitation
and settling in Bioreactor No. 1 provided an additional 17 to 67
percent removal of influent metals (primarily aluminum,
copper, iron, nickel, and zinc) from recirculated solution. An
additional 34.2 percent of the iron, 29.4 percent of the nickel,
and 12.3 percent of the zinc precipitates that were formed in
bioreactor No.l were passed out of the bioreactor No.l to
bioreactor No.2. The increase in TSS concentration in the
bioreactor effluent confirmed that solids were being passed
out of the bioreactor. On average, approximately 2.7 kg of
solids settled in Bioreactor No. 1 each day.
Precipitate formation and settling within Bioreactor No.2
occurs over a 6.2 hour HRT. Metal sulfide precipitation and
settling in Bioreactor No.2 provided an additional 3 to 19
percent removal of influent metals (primarily aluminum, iron,
and nickel) from recirculated solution. None of the aluminum,
iron, or nickel precipitates were passed out of the bioreactor.
The decrease in TSS concentration in the bioreactor effluent
confirmed that solids were retained in the bioreactor. On
average, approximately 2.7 kg of solids settled in Bioreactor
No.2 each day. Every 3 to 4 months approximately 15,000 L
of solids are flushed out of the two bioreactors to the flushing
pond. Because recirculated ARD within the two bioreactors is
near a neutral pH condition, formation and settling of
precipitate can readily occur within the bioreactors. However,
the majority of precipitate formation and settling occurs in the
settling pond and only residual concentrations of metals enter
36
-------
the bioreactors. Careful control of solids settling and depth of
accumulation within the settling pond is required to prevent
entrainment of settled solids during recirculation and
deposition of solids in the two bioreactors.
Residual metals and sulfide in settling pond effluent are
discharged to the flushing pond for extended metals and
sulfide contact, precipitate formation, and settling. Metal
sulfide, metal hydroxide, and metal oxyhydroxide precipitate
is formed and allowed to settle within the 304 hour flushing
pond HRT at 28 L/min. Extended settling provided an
additional 0.8 to 85 percent removal of influent metals
(primarily aluminum, copper, iron, and nickel) from solution.
An additional 10.8 percent of the iron precipitate that was
formed in the flushing pond was passed out of the pond to the
aeration channel. The decrease in TSS concentration in the
effluent confirmed that solids were retained in the flushing
pond. On average, approximately 5.3 kg of settled solids are
generated each day in the in the flushing pond.
Aeration promoted removal of 30 to 66 percent removal of the
remaining aluminum, copper, iron, nickel, and zinc from
solution. On average, approximately 0.1 kg of solids settled in
the aeration channel each day when considering only target
metals. However, calcium and magnesium concentrations also
increased in system effluent, resulting in a net loss of
approximately 1.6 kg of precipitate from the aeration channel
each day. TSS concentrations did not increase and the
system effluent from the aeration channel met EPA discharge
criteria. Metals dissolution and suspended solids carryover to
the aeration channel could be minimized by more frequent
removal and dewatering of settled solids from the flushing
pond. As a whole, the treatment system reduced metals
concentrations from 9.7 to 99.7 percent, with many of the
target metals exceeding 85 percent removal efficiency.
Collectively, the treatment system generated a net mass of 19
kg of solids each day. Settled solids are pumped out of the
flushing pond and settling pond and passed through bag filters
for dewatering each fall to provide adequate solids storage
capacity over the following winter. Bag filtration is discussed
under gravity flow operations above.
2.5.4 Evaluation of Solids Handling and
Disposal
This section describes solids handling activities conducted
during the operation of the bioreactor treatment system. The
discussion includes a summary of waste characterization and
handling requirements, identifies the sources and quantity of
solids from the treatment system, identifies the characteristics
of each solid waste stream, and identifies the method of
disposal for each solids waste stream.
2.5.4.1 Waste Characterization and Handling
Requirements
Bioreactor treatment of ARD generates a metal sulfide, metal
hydroxide, metal oxyhydroxide, and calcium carbonate solid
waste stream. The solid waste residuals produced by the
treatment system were analyzed for hazardous waste
characteristics. Determination of waste characteristics is
necessary to determine appropriate handling and disposal
requirements. Therefore, total and leachable metals analyses
were performed on the solid waste streams for comparison to
state of California and Federal hazardous waste classification
criteria. To determine if the solid waste streams are a Federal
Resource Conservation and Recovery Act (RCRA) waste,
TCLP results were compared to TCLP limits. To determine
whether the solid waste streams are a California hazardous
waste, total metals results (wet weight) were compared to
California total threshold limit concentration (TTLC) criteria.
If a solid waste stream exceeds either Federal TCLP criteria or
California TTLC criteria, then the waste is considered to be
hazardous and must be disposed of in a permitted treatment,
storage, and disposal (TSD) facility.
If a solid waste stream is found to be non-hazardous, then the
potential to impact water quality must be evaluated. The
teachability of metals from a solid waste stream must be
determined using the California WET procedure if disposed of
in California or another accepted leaching procedure if
disposed of in other states. Deionized water (DI) was used as
the WET leaching solution. To determine whether a non-
hazardous solid waste stream poses a threat to water quality in
California, metals concentrations in WET leachate samples
were compared to California soluble threshold limit
concentration (STLC) criteria. Solid waste stream samples
were also subject to the SPLP, a commonly accepted leaching
procedure in other states. If a solid waste stream exceeds the
California STLC criteria, then the waste is considered to be a
threat to water quality and the waste must be disposed of in a
permitted TSD facility or engineering controls implemented to
protect water quality. Interpretation of SPLP data are state-
specific and are beyond the scope of this discussion.
Evaluation of the quantity, characteristics, and disposal of
solid waste streams generated by the bioreactor treatment
system is presented in Section 2.5.4.2.
2.5.4.2 Bioreactor Treatment System Solids
Operation of the bioreactor treatment system between
November 2003 and July 2005 produced about 14.2 dry tons
(12,900 kg) of sludge (86 to 99.6 percent moisture), which
equals about 0.45 dry ton (410 kg) of sludge per million liters
of ARD treated. The estimate of solids generated includes
approximately 4.3 dry tons (3,900 kg) of bag filter solids,
37
-------
10 dry tons (9,100 kg) of settling pond sludge, and 4.3 dry treatment system operation are presented in Table 2-19. None
tons (3,900 kg) of flushing pond sludge. The sludge consists of the various sources of sludge were determined to be a
mainly of metal sulfides and hydroxides that are high in RCRA or California hazardous waste and did not pose a threat
aluminum, copper, iron, nickel, and zinc. No other waste to water quality. Bag filter solids were shipped off-site to a
streams were generated the treatment system. The municipal landfill for disposal pending designation of an on-
characteristics of the solid waste streams generated during site disposal area.
38
-------
Table 2-19. Bioreactor Treatment System Waste Characterization
Parameter
Total Metals1
(mg/kg)
Total Metals2
(mg/kg)
Exceed
TTLC?
DI WET Metals
(mg/L)
Exceed
STLC?
TCLP
(mg/L)
Exceed
TCLP?
SPLP Metals
(mg/L)
Pretreatment Pond Sludge
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Mercury
Molybdenum
Nickel
Selenium
Silver
Thallium
Vanadium
Zinc
<4.7
15.1
13.5
5.2
<0.31
11.1
97.9
487
<2.5
1.3
<0.99
111
<6.1
<0.7
12.9
7
320
<0.21
0.664
0.059
0.229
<0.014
0.488
4.31
21.4
<0.11
0.057
<0.044
4.88
<0.268
<0.031
0.568
0.308
14.1
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
<0.015
0.321
0.19
0.0995
<0.0014
0.13
1.11
4.61
0.0493
0.00087
<0.0034
1.54
0.293
<0.0023
0.0398
0.165
4.6
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
<0.0058
<0.0052
0.0677
0.003
<0.00054
<0.00084
0.166
0.0258
0.0107
0.00037
<0.0013
0.312
0.0247
<0.00092
0.0036
<0.00088
0.795
NA
No
No
NA
No
No
NA
NA
No
No
NA
NA
No
No
NA
NA
NA
0.0082
0.0903
0.105
0.0462
<0.00027
0.0725
0.174
0.614
0.0046
0.00031
<0.00067
0.373
0.0875
<0.00046
0.0194
0.0712
1.2
Settling Pond Sludge
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Mercury
Molybdenum
Nickel
Selenium
Silver
Thallium
Vanadium
Zinc
<4.9
98.4
83
18.3
1.5
17.6
378
757
6
7.9
<1
484
<6.3
0.82
18
25.8
728
<0.211
4.23
3.569
0.7869
0.0645
0.7568
16.254
32.551
0.258
0.3397
<0.043
20.812
<2.71
0.03526
0.774
1.1094
31.304
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
<0.015
0.45
0.323
0.105
0.004
0.0281
1.65
2.42
0.0307
0.0012
<0.0034
2.4
0.138
<0.0023
0.0737
0.122
3.57
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
<0.0058
<0.0052
0.0949
0.003
0.00076
0.0035
0.208
0.0165
0.0062
0.00049
<0.0013
0.407
0.015
0.0025
0.0191
<0.00088
0.586
NA
No
No
NA
No
No
NA
NA
No
No
NA
NA
No
No
NA
NA
NA
<0.0029
<0.0026
0.016
0.0002
<0.00027
0.0017
0.0045
0.0078
<0.0013
0.00034
0.0012
0.01
<0.0042
0.00099
0.0074
<0.00044
0.0135
Flushing Pond Sludge
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Mercury
Molybdenum
Nickel
Selenium
Silver
Thallium
Vanadium
Zinc
<49
172
135
11.6
4.5
27.7
409
707
<26
47
<10
627
<63
<7.2
<35
13.5
850
<0.196
0.688
0.54
0.0464
0.018
0.1108
1.636
2.828
<0.104
0.188
<0.04
2.508
<0.252
<0.288
<0.14
0.054
3.4
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
<0.015
0.016
0.076
0.0041
<0.0014
0.0022
0.0224
0.0346
<0.0065
0.00098
0.0059
0.104
<0.021
0.0032
<0.0085
0.0046
0.0546
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
<0.0058
<0.0052
0.0366
<0.00022
<0.00054
<0.00084
0.0031
0.0085
<0.0026
0.00027
0.0045
0.027
0.0189
<0.00092
<0.0034
<0.00088
0.0163
NA
No
No
NA
No
No
NA
NA
No
No
NA
NA
No
No
NA
NA
NA
<0.0029
<0.0026
0.0401
<0.00011
<0.00027
<0.00042
0.0035
0.0063
0.0018
0.00067
0.002
0.0384
0.0045
0.00092
<0.0017
0.0012
0.0086
1 Metals data reported as dry weight 2 Metals data reported as wet weight for comparison to TTLC
DI WET = Waste extraction test using deionized water SPLP = Synthetic precipitation leaching procedure
mg/kg = Milligram per kilogram STLC = Soluble threshold limit concentration
mg/L = Milligram per liter TCLP = Toxicity characteristic leaching procedure
NA = Not applicable TTLC = Total threshold limit concentration
39
-------
Table 2-19. Bioreactor Treatment System Waste Characterization (continued)
Parameter
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Mercury
Molybdenum
Nickel
Selenium
Silver
Thallium
Vanadium
Zinc
Total Metals1
(mg/kg)
Total Metals2
(mg/kg)
Exceed
TTLC?
DI WET Metals
(mg/L)
Exceed
STLC?
TCLP
(mg/L)
Exceed
TCLP?
SPLP Metals
(mg/L)
Aeration Channel Sludge
<21
163
419
1
2.4
23.7
349
110
22.2
21.9
<4.4
502
<27
<3.1
<15
37.4
431
<0.21
1.63
4.19
0.01
0.024
0.237
3.49
1.1
0.222
0.219
<0.044
5.02
<0.27
<0.031
<0.15
0.374
4.31
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
0.0474
1.93
3.55
0.0145
0.0064
0.123
4.39
1.34
0.188
0.0202
<0.0034
7.22
0.123
0.0023
0.0984
0.448
4.15
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
<0.0058
0.0466
0.303
0.00075
<0.00054
0.002
0.785
0.0204
<0.0026
0.00046
0.0021
2.43
0.0098
<0.00092
0.0186
<0.00088
0.713
NA
No
No
NA
No
No
NA
NA
No
No
NA
NA
No
No
NA
NA
NA
0.0205
0.821
1.68
0.0086
0.0042
0.0553
0.941
0.225
0.0456
0.0044
<0.00067
3.27
0.0857
<0.00046
0.0321
0.3
0.924
Bag Filter Solids
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Mercury
Molybdenum
Nickel
Selenium
Silver
Thallium
Vanadium
Zinc
5.9
14.3
10.3
19.1
3.8
15.1
416
2,030
8.9
0.18
<0.5
561
<1.3
<0.4
30.1
6
1,400
0.82
2.0
1.4
2.6
0.53
2.1
57.6
281
1.2
0.026
<0.2
77.6
<0.5
<0.5
4.2
0.83
194
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
<0.0047
<0.0037
0.125
0.246
<0.00046
0.184
0.169
0.0208
0.0572
0.00012
<0.0014
2.91
0.121
<0.00099
0.111
0.0807
0.58
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
<0.0094
<0.0074
0.013
0.00023
<0.00092
0.0373
0.0437
0.0145
0.0126
0.0022
<0.0028
0.278
0.0381
0.0036
0.0365
<0.0014
0.137
NA
No
No
NA
No
No
NA
NA
No
No
NA
NA
No
No
NA
NA
NA
<0.0047
<0.0037
0.0045
<0.000066
<0.00046
0.007
<0.00064
0.0082
0.0025
0.0024
<0.0014
0.0025
0.0091
0.0027
0.0028
0.00068
0.0071
1 Metals data reported as dry weight 2 Metals data reported as wet weight for comparison to TTLC
DI WET = Waste extraction test using deionized water SPLP = Synthetic precipitation leaching procedure
mg/kg = Milligram per kilogram STLC = Soluble threshold limit concentration
mg/L = Milligram per liter TCLP = Toxicity characteristic leaching procedure
NA = Not applicable TTLC = Total threshold limit concentration
40
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SECTION 3
TECHNOLOGY APPLICATIONS ANALYSIS
This section of the ITER describes the general applicability of
the compost-free bioreactor treatment technology to reduce
acidity and toxic levels of metals in water at ARD-
contaminated mine sites. The analysis is based on the results
from and observations made during the SITE demonstration.
3.1 Key Features
Oxidation of sulfur and sulfide minerals within the mine
workings and waste rock forms sulfuric acid (H2SO4), which
liberates toxic metals from the mine wastes creating ARD.
Biological treatment of ARD reverses this process and relies
on the biologically mediated reduction of sulfate to sulfide
followed by metal sulfide precipitation. Biologically
promoted sulfate-reduction has been attributed primarily to a
consortium of sulfate-reducing bacteria, which utilize a variety
of carbon substrates to reduce sulfate to sulfide. This process
generates hydrogen sulfide, elevates pH to about 7, and
precipitates divalent metals as metal sulfides. The following
general equations describe the sulfate-reduction and metal
sulfide precipitation processes.
2CH3CH2OH
3SO42"
3HS' + 3HCO3
3H2O
2CH3CH2OH + SO4
2 CH.COCT + HS~ + H2O
MS' + NT
• MS + 2W
(1)
(2)
(3)
Here ethanol is the carbon source and SO42" is the terminal
electron acceptor in the electron transport chain of sulfate-
reducing bacteria. Reaction No.l causes an increase in
alkalinity and a rise in pH, while reaction No.2 results in the
generation of acetate rather than complete oxidation to
carbonate. HS" then reacts with a variety of divalent metals
(M2+), resulting in a metal sulfide (MS) precipitate.
At Leviathan Mine, biological treatment is conducted in two
compost-free gravity-flow bioreactors, two settling ponds, and
an aeration channel. The bioreactors are filled with river rock
because of the ease at which precipitates can be flushed
through the matrix and the stability (little compaction) of the
matrix. Operated in gravity flow mode, ARD is introduced to
the pretreatment pond, where sodium hydroxide is added to
adjust the influent pH of 3.1 up to 4 to maintain a favorable
environment for sulfate-reducing bacteria and ethanol is added
as a carbon source. Minimal chemically-mediated metals
precipitation occurs in the pretreatment pond. ARD from the
pre-treatment pond then flows through the first bioreactor to
biologically reduce sulfate to sulfide. Excess sulfide
generated in the first bioreactor is passed, along with partially
treated ARD water, through to the second bioreactor for
additional metals removal. Precipitates in effluent from the
second bioreactor are settled in a continuous flow settling
pond.
Operated in recirculation mode, metal-rich influent ARD is
combined with sodium hydroxide and sulfide-rich water
discharged from the second bioreactor to precipitate metals in
the settling pond rather than in the bioreactors. Precipitation
of metal sulfides downstream of the two bioreactors greatly
reduces the need for flushing and the associated stress on
bacteria in the two bioreactors. A portion of the pond
supernatant containing minimal residual metals and excess
sulfate is pumped to the first bioreactor and combined with
alcohol feed stock to promote additional sulfate reduction to
sulfide in the two bioreactors. The pH of the supernatant
recirculated through the bioreactors is near neutral, providing
optimal conditions for sulfate-reducing bacteria growth.
During both modes of operation, the effluent from the
continuous flow settling pond flows through a rock lined
aeration channel to promote gas exchange prior to effluent
discharge. Precipitate slurry is periodically flushed from the
bioreactors to prevent plugging of the river rock matrix and
provide adequate volume in the settling pond, and settled in a
flushing pond. Settled solids from the flushing pond are
periodically dewatered using bag filters.
41
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3.2 Applicable Wastes
Conventional methods of treating ARD involve the capture,
storage, and batch or continuous treatment of water using a
large quantity of added lime, which neutralizes acidity and
precipitates a large volume of metal hydroxide sludge.
Biological treatment using surf ate-reducing bacteria is
applicable to any waste stream containing metals and sulfate
ion, requires a small quantity of base addition and a liquid
carbon source, and generates a relatively small volume of
metal sulfide sludge. Metals typically treated include
aluminum, arsenic, cadmium, chromium, copper, iron, lead,
nickel, and zinc. Biological treatment is also passive,
requiring less labor for system O&M.
The compost-free bioreactor treatment system in operation at
the Leviathan Mine site is an improvement to the current
wood chip, compost, and manure biological treatment systems
in place or being evaluated at many facilities today. The
compost-free bioreactor technology removes the uncertainties
related to carbon availability and sulfate reduction efficiency
through the use of a liquid carbon substrate (ethanol). The
compost-free bioreactor technology also eliminates the
problems associated with matrix compaction and short
circuiting through the use of river rock, which allows rapid
flushing of solids in comparison to compost and wood chip
matrices.
3.3 Factors Affecting Performance
Several factors can influence the performance of the
bioreactor treatment system demonstrated at Leviathan Mine.
These factors can be grouped into three categories: (1) mine
drainage characteristics, (2) operating parameters, and (3)
system design. The bioreactor treatment system is capable of
treating a broad range of metals in ARD. The level of acidity,
metals concentration, and metals composition directly impact
the quantity of sulfide ion that must be generated, and the
subsequent sodium hydroxide and ethanol dosages required to
neutralize acidity and in conjunction with sulfate-reducing
bacteria, generate the sulfide necessary to precipitate target
metals.
Operating parameters for the bioreactors also directly impact
system performance. Optimizing and limiting fluctuations in
reagent dosages, bioreactor HRT, bioreactor temperature,
gravity and recirculation flow rates, and settling pond HRT all
impact the activity of sulfate-reducing bacteria, generation of
sulfides, and removal of target metals. The system should be
designed and operated to limit stress placed on the sulfate-
reducing bacteria in the bioreactors. The system should be
operated to allow as near neutral a pH in the bioreactors as
possible and maintain a consistent ethanol dosage rate.
In order to minimize fluctuations in pH and maintain a near
neutral pH, operation of the system in recirculation mode was
found to be optimal. Sodium hydroxide is added to the
settling pond along with sulfide rich water to precipitate metal
sulfides from solution. The pond supernatant, at a near neutral
pH and with low metals concentrations, is recirculated through
the bioreactors, which favors sulfate-reducing bacteria and
minimizes metal toxicity. Settling of metal sulfides in the
pond rather than the bioreactors also minimizes the need for
bioreactor flushing and associated biological stress. In the
absence of a recirculation pump, the system design should
include a pretreatment pond upstream of the treatment system
to reduce fluctuations in acidity and metals concentration in
influent ARD and allow extended mixing time for sodium
hydroxide and ethanol reagents added to solution, all of which
will promote a tighter control of reaction chemistry enter the
bioreactors.
In locations where extremely cold winter conditions persist
over several months, consideration should be given to
ensuring that the bioreactor and settling ponds are of sufficient
depth to prevent deep freezing and insulate the active portion
of the bioreactor from extreme cold. The bioreactors at
Leviathan Mine are 3 meters deep and were not impact by
extreme cold below a depth of approximately 0.6 meter. In
addition, the settling ponds did not freeze below about 0.6
meter.
The rock substrate within the bioreactors is essentially non-
compactable over time in comparison to traditional wood chip,
compost, and manure substrate-based bioreactors. A stable
substrate minimizes dead zones and preferential pathways
within a bioreactor over time. The use of ethanol as a carbon
substrate rather than traditional wood- or manure-based
carbon sources provides a stable carbon supply and is a more
efficient source of reducing equivalents for surf ate-reducing
bacteria. Together, a rock matrix and a liquid carbon substrate
allow long-term operation of a treatment system that
traditionally requires excavation and replace of the wood or
manure substrate every five years, depending on the initial
quantity of wood or manure used.
Finally, the method and duration of precipitate settling and
separation also impacts system performance. The treatment
system relies on sodium hydroxide addition to generate
settleable solids, a large settling pond to allow extended
settling of pin floe, and bag filters to dewater sludge pumped
out of the settling pond. A second settling pond should also
be considered during system design to provide the system
operator some room for error during system upsets. If sodium
hydroxide addition to the settling pond is not controlled above
a pH of 8, target metals may dissolve back into solution.
3.4 Technology Limitations
In general, the limitations of the bioreactor treatment system
implemented at Leviathan Mine were not related to the
applicability of the technology, but rather to operational issues
42
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due to weather conditions, maintenance problems, and the
remoteness of the site. The technology is not limited by the
sub-freezing temperatures encountered in the high Sierra
Nevada during the winter months. However, biological
activity did slow resulting in decreased sulfate reduction to
sulfide. Effluent discharge standards were met as the flow of
ARD entering the bioreactor treatment system also decreased
during the winter. When designing systems for extremely
cold winters, consideration should be given to constructing
bioreactors of sufficient size to meet winter HRT requirements
and depth to buffer freezing temperatures near the ground
surface. In addition, adjustable standpipes in below grade
vaults should be used to control the flow of water rather than
mechanical valves, which are subject to freezing during the
winter.
During extended operation of the bioreactor treatment system,
reagent metering and water recirculation pumps and the
generator that provided power to these pumps were
susceptible to failure. In addition, aboveground influent ARD
transfer and partially treated recirculation pipelines were
susceptible to breakage. These limitations are currently being
mitigated by 1) developing wind, solar, and hydroelectric
power sources, 2) installing redundant pumps, and 3) placing
transfer lines below grade. Overall, the bioreactor treatment
system required minimal maintenance (1 to 2 days a week).
The remoteness of the site also created logistical challenges in
maintaining operation of the bioreactor treatment system. A
winter snow pack from November through May prevents site
access to all delivery vehicles except for snowmobiles.
Consumable materials, such as sodium hydroxide, ethanol,
and diesel fuel (to power a generator) must be transported to
and stored in bulk at the site during the summer. Sludge
transfer from the settling ponds, dewatering, and on- or off-
site disposal must also be performed during the summer
months to provide sufficient settling pond capacity during the
following winter months. Careful planning is essential to
maintain supplies of consumable materials and replacement
equipment at a remote site such as Leviathan Mine.
3.5 Range of Suitable Site Characteristics
This section describes the site characteristics necessary for
successful application of the bioreactor treatment technology.
Staging Area and Support Facilities: For full-scale
bioreactor treatment systems such as those in operation at
Leviathan Mine, minimal staging areas and support facilities
are necessary for continuous operation of the treatment
system. A small staging area is needed for storage of
consumable materials, and supplies; loading and unloading
equipment; and for placement of a Connex, which is used for
storage of spare parts and equipment that are not weather
resistant. Additional space is necessary for placement of a
health and safety eyewash and shower; a portable toilet; and
power generating equipment. The staging and storage areas
required for a treatment system should range from 300 and
500 square meters and are usually located adjacent to the
treatment system. A reagent storage area of about 50 square
meters for bulk quantities of ethanol and sodium hydroxide is
also required up gradient of or at the head of the treatment
system.
Treatment System Space Requirements: To conduct full-
scale bioreactor treatment of ARD, the main site requirement
at the Leviathan Mine site was developing adequate space for
the treatment system, staging areas, and support facilities.
Space is needed for reagent storage tanks, a pretreatment
pond, bioreactor ponds, settling ponds, an aeration channel,
and bag filters. Additional space was required adjacent to the
treatment system for storage of spare parts and equipment, for
loading and unloading equipment, supplies, and reagents, and
for placement of operating facilities such eye wash stations,
fuel storage tank, and power generating equipment. Overall,
the space requirement for the bioreactor treatment of ARD at a
flow rate of 114 L/min at Leviathan Mine is about 3,000
square meters.
Climate: Operation of the bioreactor treatment system is
slightly affected by freezing temperatures. In areas where
freezing temperatures are normal throughout the winter
months, such as at the Leviathan Mine site, biological activity
does slow resulting in decreased sulfate reduction to sulfide.
At Leviathan Mine, effluent discharge standards were
generally met as the flow of ARD entering the bioreactor
treatment system also decreased during the winter. When
designing systems for extremely cold winters, consideration
should be given to constructing bioreactors of sufficient size
to meet winter HRT requirements and depth to buffer freezing
temperatures near the ground surface. In addition, adjustable
standpipes in below grade vaults should be used to control the
flow of water rather than mechanical valves, which are subject
freezing during the winter.
The remoteness of the site also created logistical challenges in
maintaining operation of the bioreactor treatment system. A
winter snow pack from November through May prevents site
access to all delivery vehicles except for snowmobiles.
Consumable materials, such as sodium hydroxide, ethanol,
and diesel fuel (to power a generator) must be transported to
and stored in bulk at the site during the summer. Sludge
transfer from the settling ponds, dewatering, and on- or off-
site disposal must also be performed during the summer
months to provide sufficient settling pond capacity during the
following winter months. Careful planning is essential to
maintain supplies of consumable materials and replacement
equipment at a remote site such as Leviathan Mine.
Utilities: The main utility requirement for the bioreactor
treatment system is electricity, which is used to operate
reagent delivery pumps, water recirculation pump, sludge
transfer pumps, and site work lighting. The bioreactor
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treatment system, operated in recirculation mode, requires less
than 0.6 kilowatt (KW) hour of electricity for continuous
operation. Power for recirculation mode is provided by a 6
KW-hour diesel generator. Diesel fuel for the generator is
stored in a 3,785 L above ground tank. The bioreactor
treatment system, operated in gravity flow mode, requires less
than 0.1 KW hour of electricity for continuous operation as a
recirculation pump is not required. Power for the gravity flow
mode of operation is provided by a solar panel and storage
batteries. A wind or water turbine and storage battery may
also be used to provide power. Satellite phone service is also
required due to the remoteness of the site.
Supervisory Control and Data Acquisition (SCADA) service
through a satellite uplink may also be used to monitor water
chemistry and control dosing of ethanol and sodium hydroxide
to the bioreactor treatment system.
3.6 Personnel Requirements
Personnel requirements for operation of the treatment system
following initial design and construction can be broken down
into the following activities: startup and acclimation, and
O&M. System start-up and acclimation includes the labor to
setup pumps and pipes, fill and recirculate ARD within the
system, adjust system hydraulics and reagent dosages, and
optimize the operational HRT to meet discharge standards.
System startup and acclimation occurs once after initial
system construction as the system is design to operate year
round, even in extremely cold weather. System start up of the
treatment system will take a two-person crew two weeks to
complete. After system construction and start up, an
acclimation period is necessary to allow for the acclimation of
sulfate-reducing bacteria to the source water, optimization of
carbon substrate dosage and pH within the bioreactors, and the
slow ramp up of ARD flow to attain discharge standards.
System acclimation will require only one person visiting the
system 3 days a week over a 10 week period.
Field personnel are necessary to operate the treatment system,
perform weekly maintenance, collect weekly discharge
monitoring samples, monitor unit operation chemistry and
flow rates, and to adjust ethanol and sodium hydroxide
dosages, adjust unit operation HRT, and adjust recirculation
rates. Due to the passive nature of the treatment system,
minimal O&M labor is necessary in comparison to an active
treatment system. Long-term O&M of the treatment system
will require only one person visiting the system 1 day a week
over the course of a year.
In addition to field personnel, support staff is required for
project management and administrative support functions.
The level of effort required for support staff is approximately
15 percent of the total project level of effort.
3.7 Materials Handling Requirements
There is one process residual associated with bioreactor
treatment of ARD. The process produces a relatively small
quantity of sludge containing metal sulfides, oxides, and
oxyhydroxides. During operation from November 2003
through July 2005, the bioreactor generated about 14.2 dry
tons (12,900 kg) of sludge consisting mainly of iron sulfide.
This equals 1.7 dry tons (1,550 kg) of sludge per million
gallons (0.45 dry ton [410 kg] per million liters) of ARD
treated.
The solid waste residuals produced by the treatment system
were analyzed for hazardous waste characteristics. Total
metals and leachable metals analyses were performed on the
solid wastes for comparison to California and Federal
hazardous waste classification criteria. To determine whether
the residuals are California hazardous waste, total metals
results were compared to TTLC criteria. To determine
whether metals concentrations in the solid waste residuals
pose a threat to water quality, DI WET leachate results were
compared to STLC criteria. To determine if the residuals are a
RCRA waste, TCLP leachate results were compared to TCLP
limits. The hazardous waste characteristics determined for the
solid waste stream are presented in Table 3-1. None of the
solid wastes were found to be hazardous or a threat to water
quality; however, the solids were disposed of off site pending
designation of an on-site disposal area.
3.8 Permit Requirements
Actions taken on-site during a CERCLA cleanup action must
comply only with the substantive portion of a given
regulation. On-site activities need not comply with
administrative requirements such as obtaining a permit, record
keeping, or reporting. Actions taken off-site must comply
with both the substantive and administrative requirements of
applicable laws and regulations. All actions taken at the
Leviathan Mine Superfund site were on-site; therefore permits
were not obtained.
Permits that may be required for off-site actions or actions at
non-CERCLA sites include: a permit to operate a hazardous
waste treatment system, an National Pollutant Discharge and
Elimination System (NPDES) permit for effluent discharge, an
NPDES permit for discharge of storm water during
construction activities, and an operations permit from a local
air quality management district (AQMD) for activities
generating paniculate emissions. Permits from local agencies
may also be required for grading, construction, and
operational activities; transport of oversized equipment on
local roads; and transport of hazardous materials on local
roads.
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Table 3-1. Determination of Hazardous Waste Characteristics for Bioreactor Solid Waste Streams
Treatment
System
Bioreactor
Treatment
System
Solid Waste Stream
Dewatered Sludge
Pretreatment Pond
Settling Pond
Flushing Pond
Total Solid
Waste Generated
4.3 dry tons
Moved into Flushing Pond
10 dry tons (estimated)
4.3 dry tons (estimated)
TTLC
Pass or
Fail
P
P
P
P
STLC
Pass or
Fail
P
P
P
P
TCLP
Pass or
Fail
P
P
P
P
Waste Handling Status
Off-site Disposal
Moved into Flushing Pond
Pending Filtration
Pending Filtration
STLC = Soluble limit threshold concentration TTLC = Total threshold limit concentration
TCLP = Toxicity characteristic leaching procedure 1 dry ton = 907 kilogram
3.9 Community Acceptance
Community acceptance for the compost-free bioreactor
treatment system operated at Leviathan Mine is positive. The
diversion and treatment of ARD at the mine site is seen as a
necessary and positive step towards reestablishing a quality
watershed within the Sierra Nevada mountain range. The
treatment system is able to meet discharge standards and
operates on a year round basis, promoting improved watershed
and fishery health. Continued community involvement and
regulatory agency support will be necessary for long term
treatment and monitoring at a mine site such as Leviathan
Mine.
Operation of the bioreactor treatment system presents minimal
to no risk to the public since all system components and
treatment operations occur within a contained site. Solids
generated during the treatment process are nonhazardous.
Hazardous chemicals used in the treatment system include
ethanol, sodium hydroxide, and diesel fuel for generator
power. These chemicals pose the highest risk to the public
during transportation to the site by truck and trailer.
Appropriate Department of Transportation (DOT) regulations
are followed during shipment of these chemicals to minimize
potential impacts to the public. During operation, the diesel
generator used to power the treatment system creates the most
noise and air emissions at the site. Hydrogen sulfide gas is
also generated by the treatment process, but is only of concern
within the treatment system valve vaults. Because of the
remoteness of the Leviathan Mine site, the public is not
impacted by these issues. Alternative power sources are
currently being evaluated, including wind and water turbines,
which will replace or augment the diesel-powered generator.
3.10 Availability, Adaptability, and
Transportability of Equipment
The components of the compost-free bioreactor treatment
system are generally available and not proprietary. System
process components include (1) distribution piping and
valving, pond liners, rock substrate, recirculation pumps, and
reagent storage tanks; (2) control equipment such as a
SCADA system, a pH monitoring system, a recirculation
pump controller, and ethanol and sodium hydroxide dosage
and feed systems; and (3) solids handling equipment such as
sludge pumps, bag filters, and roll-off bins. This equipment is
available from numerous suppliers throughout the country and
may be ordered in multiple sizes to meet flow requirements
and treatment area accessibility. An integrated design is
recommended to properly size and assemble individual
components for proper system operation.
Transport of earth moving equipment, piping, stairs,
bioreactor rock substrate, and reagent storage tanks to a site
may require handling as oversize or wide loads. Additional
consideration should be given to the stability of mine access
roads, bridge clearances, and load limits for large shipments.
Process reagents and consumables, such as ethanol, sodium
hydroxide, and generator fuel, are considered hazardous
materials and will require stable site access roads for delivery.
3.11 Ability to Attain ARARs
Under CERCLA, remedial actions conducted at Superfund
sites must comply with Federal and state (if more stringent)
environmental laws that are determined to be applicable or
relevant and appropriate. Applicable or relevant and
appropriate requirements (ARAR) are determined on a site-
specific basis by the EPA remedial project manager. They are
used as a tool to guide the remedial project manager toward
the most environmentally safe way to manage remediation
activities. The remedial project manager reviews each Federal
environmental law and determines if it is applicable. If the
law is not applicable, then the determination must be made
whether the law is relevant and appropriate. Actions taken on-
site during a CERCLA cleanup action must comply only with
the substantive portion of a given ARAR. On-site activities
need not comply with administrative requirements such as
obtaining a permit, record keeping, or reporting. Actions
conducted off-site must comply with both the substantive and
administrative requirements of applicable laws and
regulations.
On-site remedial actions, such as the compost-free bioreactor
treatment system in operation at the Leviathan Mine site, must
comply with Federal and more stringent state ARARs,
however, ARARs may be waived under six conditions: (1) the
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action is an interim measure, and the ARAR will be met at
completion; (2) compliance with the ARAR would pose a
greater risk to human health and the environment than
noncompliance; (3) it is technically impracticable to meet the
ARAR; (4) the standard of performance of an ARAR can be
met by an equivalent method; (5) a state ARAR has not been
consistently applied elsewhere; and (6) ARAR compliance
would not provide a balance between the protection achieved
at a particular site and demands on the Superfund for other
sites. These waiver options apply only to Superfund actions
taken on-site, and justification for the waiver must be clearly
demonstrated.
The following sections discuss and analyze specific
environmental regulations pertinent to operation of the
bioreactor treatment system, including handling, transport, and
disposal of both hazardous and non-hazardous treatment
residuals. ARARs identified include: (1) CERCLA; (2)
RCRA; (3) the Clean Air Act (CAA); (4) the Clean Water Act
(CWA); (5) Safe Drinking Water Act (SDWA); and (6)
Occupational Safety and Health Administration (OSHA)
regulations. These six general ARARs, along with additional
state and local regulatory requirements (which may be more
stringent than Federal requirements) are discussed below.
Specific ARARs that may be applicable to the bioreactor
treatment system are identified in Table 3-2.
3.11.1 Comprehensive Environmental Response,
Compensation, and Liability Act
CERCLA of 1980 authorizes the Federal government to
respond to releases or potential releases of any hazardous
substance into the environment, as well as to releases of
pollutants or contaminants that may present an imminent or
significant danger to public health and welfare or to the
environment. As part of the requirements of CERCLA, EPA
has prepared the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP) for hazardous substance
response. The NCP, codified in Title 40 Code of Federal
Regulations (CFR) Part 300, delineates methods and criteria
used to determine the appropriate extent of removal and
cleanup for hazardous waste contamination.
The 1986 SARA amendment to CERCLA directed EPA to:
• Use remedial alternatives that permanently and
significantly reduce the volume, toxicity, or mobility
of hazardous substances, pollutants, or contaminants.
• Select remedial actions that protect human health and
the environment, are cost-effective, and involve
permanent solutions and alternative treatment or
resource recovery technologies to the maximum
extent possible.
• Avoid off-site transport and disposal of untreated
hazardous substances or contaminated materials
when practicable treatment technologies exist
(Section 12 l[b]).
In general, two types of responses are possible under
CERCLA: removal and remedial actions. Removal actions
are quick actions conducted in response to an immediate threat
caused by release of a hazardous substance. Remedial actions
involve the permanent reduction of toxicity, mobility, and
volume of hazardous substances or pollutants. The bioreactor
treatment technology implemented at the Leviathan Mine
Superfund site fall under the purview of CERCLA and SARA;
the treatment system is operated on site and reduces the
mobility of toxic metals through metal sulfide precipitation
and volume through metal concentration in sludge and bag
filter solids. The technologies are protective of human health
and the environment, cost effective, and permanent.
The bioreactor treatment technology can be applied at sites
such as Leviathan Mine and operated as long-term CERCLA
remedial actions; however, it may also be designed and
operated for short term operation at a site in support of a
CERCLA removal action, where immediate removal of toxic
metals from a waste stream is necessary.
3.11.2 Resource Conservation and Recovery Act
RCRA, an amendment to the Solid Waste Disposal Act, was
enacted in 1976 to address the problem of safe disposal of the
enormous volume of municipal and industrial solid waste
generated annually. The Hazardous and Solid Waste
Amendments of 1984 greatly expanded the scope and
requirements of RCRA. Regulations in RCRA specifically
address the identification and management of hazardous
wastes. Subtitle C of RCRA contains requirements for
generation, transport, treatment, storage, and disposal of
hazardous waste, most of which are applicable to CERCLA
actions. In order to generate and dispose of a hazardous
waste, the site responsible party must obtain an EPA
identification number. However, mining wastes are generally
not subject to regulation under RCRA (see the Bevill
Amendment at Section 3001(a)(3)(A)(ii)), unless the waste is
disposed of off-site. For treatment residuals determined to be
RCRA hazardous, substantive and administrative RCRA
requirements must be addressed if the wastes are shipped off
site for disposal. If treatment residuals remain on-site, the
substantive requirements of state disposal and siting laws and
the Toxic Pits Control Act may be relevant and appropriate.
Criteria for identifying RCRA characteristic and listed
hazardous wastes are included in 40 CFR Part 261 Subparts C
and D. Other applicable RCRA requirements include
hazardous waste manifesting for off-site disposal and time
limits on accumulating wastes.
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Table 3-2. Federal Applicable or Relevant and Appropriate Requirements for the Bioreactor Treatment System
Regulated Activity
Characterization of
untreated AMD and ARD
Construction of
Treatment System
Treatment System
Operation
Determination of Cleanup
Standards
Waste Disposal
ARAR
RCRA: 40 CFR Part 261 or state
equivalent
OSHA: 29 CFR 1910.120
CAA: 40 CFR Part 50 or state
equivalent
CWA: 40 CFR Part 122
OSHA: 29 CFR 1910.120
RCRA: 40 CFR Part 264 or state
equivalent
CAA: 40 CFR Part 50 or state
equivalent
SARA: Section 121(d)(2)(A)(ii)
SDWA: 40 CFR Part 141
RCRA: 40 CFR Part 261 or state
equivalent
RCRA: 40 CFR Part 262 and
263
CWA: 40 CFR Part 125
Description
Standards that apply to identification and characterization of
wastes.
Protection of workers from toxic metals during earth moving
activities and system construction.
Standards that apply to the emission of particulates and toxic
pollutants.
Standards for discharge of storm water generated during
construction activities. Requires compliance with best
management practices and discharge standards in nationwide
storm water discharge permit for construction activities.
Protection of workers from toxic metals and hydrogen sulfide gas
during system operation, splashes during sodium hydroxide
handling, and dust emissions during treatment residual handling.
Standards apply to treatment of wastes in a treatment facility.
Standards that apply to the emission of particulates and toxic
pollutants.
Standards that apply to pollutants in waters that may be used as a
source of drinking water.
Standards that apply to identification and characterization of
wastes.
Standards that apply to generators of hazardous waste.
Standards for discharge of effluent to a navigable waterway.
Requires a NPDES permit for discharge to a navigable waterway.
Applicability
Not applicable as mine wastes are not subject to RCRA under the Bevill
Amendment.
Applicable. Provide air monitoring and appropriate personnel protective
equipment.
Relevant and appropriate. Control emissions during earthwork using
engineering controls. May require air monitoring and record keeping.
Not applicable to a CERCLA action; however, the substantive requirements are
relevant and appropriate. Best management practices should be implemented to
meet discharge standards.
Applicable. Provide appropriate personnel protective equipment, air
monitoring, and if necessary supplied air or blowers.
Not applicable as mine wastes are not subject to RCRA under the Bevill
Amendment. However, may be relevant and appropriate. Requires operational
and contingency planning as well as record keeping.
Relevant and appropriate. Control emissions during treatment residual handling
using engineering controls. May require air monitoring and record keeping.
Not applicable for removal actions. Effluent must meet interim discharge
standards specified in the action memorandum. Applicable for remedial actions.
Effluent must obtain MCL and to the extent possible MCLGs.
Applicable only when treatment residuals are disposed of off-site. May be
relevant and appropriate for determination of waste type to guide selection of
appropriate on-site disposal requirements.
Applicable for off-site disposal of hazardous treatment residuals. Requires
identification of the generator and disposal at a RCRA-permitted facility.
Not applicable to a CERCLA action; however, the substantive requirements are
relevant and appropriate. Discharge standards may be more stringent than
MCLs or MCLGs due to potential environmental impacts.
AMD = Acid mine drainage MCL = Maximum contaminant level
ARAR = Applicable or relevant and appropriate requirement MCLG = Maximum contaminant level goal
ARD = Acid rock drainage NPDES = National Pollutant Discharge Elimination System
CAA = Clean Air Act OSHA = Occupational Safety and Health Administration
CERCLA = Comprehensive Environmental Response, Compensation, and Liability Act RCRA = Resource Conservation and Recovery Act
CFR = Code of Federal Regulation SARA = Superfund Amendments and Reauthorization Act
CWA = Clean Water Act SDWA = Safe Drinking Water Act
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At Leviathan Mine, treatment residuals generated from the
bioreactor treatment system have been determined to be non-
hazardous wastes. Non-hazardous waste residuals are either
stored or disposed of on site.
3.11.3 Clean Air Act
The CAA establishes national primary and secondary ambient
air quality standards for sulfur oxides, paniculate matter,
carbon monoxide, ozone, nitrogen dioxide, and lead. It also
limits the emission of 189 listed hazardous pollutants. States
are responsible for enforcing the CAA. To assist in this, air
quality control regions (ACQR) were established. Allowable
emission limits are determined by the AQCR and AQMD
subunits. The emission limits are established based on
attainment of national ambient air quality standards.
The CAA requires that TSD facilities comply with primary
and secondary ambient air quality standards. Emissions
resulting from solids handling during the construction and
operation of the bioreactor treatment system may need to meet
air quality standards. For example, dust generated during
earthwork and residual solids handling may be regulated by a
local AQMD. No air permits are required for the bioreactor
treatment system operated at the Leviathan Mine Superfund
site; however, dust emissions are limited through careful
handling and maintaining soil moisture during construction
and system operation.
3.11.4 Clean Water Act
The objective of the CWA is to restore and maintain the
chemical, physical, and biological integrity of the nation's
waters by establishing Federal, State, and local discharge
standards. If treated water is discharged to surface water
bodies or publicly-owned treatment works (POTW), CWA
regulations will apply. A facility discharging water to a
navigable waterway must apply for a permit under the
NPDES. NPDES discharge permits are designed as
enforcement tools with the ultimate goal of achieving ambient
water quality standards. Discharges to POTWs also must
comply with general pretreatment regulations outlined in 40
CFR Part 403, as well as other applicable state and local
administrative and substantive requirements.
Treated effluent from the bioreactor treatment system is
discharged to Aspen Creek, if EPA interim discharge
standards (pre-risk assessment and record of decision) are met.
An NPDES permit is not required under CERCLA, although
the substantive requirements of the CWA are met.
3.11.5 Safe Drinking Water Act
The SDWA of 1974 and the Safe Drinking Water
Amendments of 1986 require EPA to establish regulations to
protect human health from contaminants in drinking water.
The law authorizes national drinking water standards and a
joint Federal-State system for ensuring compliance with these
standards. The National Primary Drinking Water Standards
are found at 40 CFR Parts 141 through 149. These standards
are expressed as maximum contaminant levels (MCL) and
maximum contaminant level goals (MCLG). Under CERCLA
(Section 121(d)(2)(A)(ii)), remedial actions are required to
meet MCLs and MCLGs when relevant and appropriate. State
drinking water requirements may also be more stringent than
Federal standards.
Effluent from the bioreactor treatment system discharges to
Aspen Creek, a tributary to Leviathan Creek which is a
potential source of drinking water. Effluent from the
treatment system generally met the EPA interim (pre-risk
assessment and record of decision) discharge standards;
however, iron concentrations do not meet the Federal
secondary MCL. Attainment of the secondary MCL for iron is
fully achievable through addition of more sodium hydroxide
or increased HRT; however, under the current EPA action
memorandum, operation of the Leviathan Mine bioreactor
treatment system to meet MCLs is not required.
3.11.6 Occupational Safety and Health Act
CERCLA remedial actions and RCRA corrective actions must
be conducted in accordance with OSHA requirements detailed
in 29 CFR Parts 1900 through 1926, in particular Part
1910.120, which provides for health and safety of workers at
hazardous waste sites. On-site construction at Superfund or
RCRA corrective action sites must be conducted in
accordance with 29 CFR Part 1926, which describes safety
and health regulations for construction sites. State OSHA
requirements, which may be significantly stricter than Federal
standards, also must be met. Workers involved with the
construction and operation of the bioreactor treatment system
are required to have completed an OSHA training course and
be familiar with OSHA requirements relevant to hazardous
waste sites. Workers on hazardous waste sites must also be
enrolled in a medical monitoring program.
Minimum personal protective equipment (PPE) for workers at
the Leviathan Mine site includes gloves, hard hat, steel-toe
boots, and Tyvek® coveralls PPE, including respirators, eye
protection, and skin protection is required when handling
ARD and sodium hydroxide. Based on contaminants and
chemicals used at the site, the use of air purifying respirators
is not required. However, hydrogen sulfide gas generated by
the bioreactors may accumulate in valve vaults. Therefore, the
work area should be monitored for hydrogen sulfide gas and a
blower or supplied air should be available to mitigate any
hazards. Noise levels are generally not high, except during
earthwork activities, which involve the operation of heavy
equipment. During these activities, noise levels must be
monitored to ensure that workers are not exposed to noise
levels above a time-weighted average of 85 decibels over an
48
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eight-hour day. If noise levels exceed this limit, workers are
required to wear hearing protection.
3.11.7 State Requirements
State and local regulatory agencies may require permits prior
to operation of a bioreactor treatment system. Most Federal
permits will be issued by an authorized state agency. An air
permit from the local AQMD may be required if air emissions
in excess of regulatory standards are anticipated. State and
local agencies will have direct regulatory responsibility for all
environmental concerns. If a removal or remedial action
occurs at a Superfund site, Federal agencies, primarily EPA,
will provide regulatory oversight. If off-site disposal of
contaminated waste is required, the waste must be taken to the
disposal facility by a licensed transporter.
3.12 Technology Applicability to Other Sites
Bioreactor treatment of ARD at Leviathan Mine was evaluated
for applicability to other mine sites based on the nine criteria
used for decision making in the Superfund feasibility study
process. The nine criteria and the results of the evaluation are
summarized in Table 3-3. The bioreactor treatment system
evaluated was specifically designed to treat ARD at the mine
site to EPA interim discharge standards for aluminum, arsenic,
copper, iron, and nickel. In addition to the five primary target
metals of concern, EPA identified cadmium, chromium, lead,
selenium, and zinc as secondary water quality indicator
metals. The treatment system implemented at Leviathan Mine
was also successful at reducing concentrations of these
secondary metals in the ARD to below EPA interim discharge
standards. The treatment system can be modified to treat
wastes with varying metals concentrations and acidity.
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Table 3-3. Feasibility Study Criteria Evaluation for the Bioreactor Treatment System at Leviathan Mine
Criteria
Technology Performance
Overall Protection of
Human Health and the
Environment
Bioreactor treatment has been proven to be extremely effective at reducing concentrations of aluminum, copper, iron, nickel,
zinc, and other dissolved metals in ARD. The bioreactor treatment system evaluated at Leviathan Mine reduced the
concentrations of toxic metals in ARD, which was historically released to Aspen and Leviathan Creeks, to below EPA interim
discharge standards, which were established to protect water quality and the ecosystem in Aspen and Leviathan Creeks and
down-stream receiving waters. Resulting metals-enriched solid wastes were determined to be non-hazardous based on State and
Federal criteria and do not pose a threat to water quality. The solid waste can be used disposed of at an off-site non-hazardous
waste repository or on-site as a soil amendment depending regulatory approval.
Compliance with Applicable
or Relevant and Appropriate
Requirements (ARAR)
The bioreactor treatment system is generally compliant with EPA interim (pre-risk assessment and record of decision) discharge
standards for the Leviathan Mine site. However, the effluent from the treatment system did not always meet the EPA interim
discharge standards for the site or the secondary maximum contaminant limit (MCL) for iron, which could easily be met with
additional sodium hydroxide dosing. No hazardous process residuals are generated by the treatment system.
Long-term Effectiveness
and Performance
A bioreactor treatment system has been in operation at Leviathan Mine since 1996. The current full-scale compost-free
bioreactor treatment system has been in operation since the summer of 2003. By the fall of 2003, the entire ARD flow from
Aspen Seep was being treated by the full-scale system. The treatment system has consistently met EPA interim discharge
standards, with the exception of iron, since the fall of 2003. The treatment system operates year round; therefore, discharge of
metals-laden ARD has not occurred from the mine site since initiation of treatment. The treatment system continues to be
operated by UNR and ARCO. Long-term optimization of the treatment system will likely refine sodium hydroxide dosage
necessary for iron polishing, evaluate alternate sources of base addition, optimize recirculation rates for sulfide generation,
improve solids handling and dewatering processes, and demonstrate whether wind, solar, or a water turbine can meet the power
required for chemical dosage and recirculation pumps.
Reduction of Toxicity,
Mobility, or Volume
through Treatment
Bioreactor treatment significantly reduces the mobility and volume of toxic metals from ARD at Leviathan Mine. The dissolved
toxic metals are precipitated from solution, concentrated, and dewatered removing toxic levels of metals from the ARD. The
bioreactor treatment does produce a solid waste; however, the waste generated has been determined to be non-hazardous and
can be disposed of on site.
Short-term Effectiveness
The resulting effluent from the bioreactor treatment system does not pose any risks to human health. The sodium hydroxide
solution, ethanol feedstock, and biologically-generated hydrogen sulfide gas, each having potentially hazardous chemical
properties, may pose a risk to site workers during treatment system operation. Exposure to these hazardous chemicals must be
mitigated through engineering controls and proper health and safety protocols.
Implementability
The bioreactor treatment technology relies on a relatively simple biologically-mediated sulfate reduction and metal sulfide
precipitation process and can be constructed using readily available equipment and materials. The technology is not proprietary,
nor does it require proprietary equipment or reagents. Once installed, the system can be optimized and maintained indefinitely.
System startup and biological acclimation can take up to three months, depending on target metal concentrations and weather
conditions. Routine maintenance is required, involving a weekly visit by an operator to ensure reagent and recirculation pumps
are operational, replenish reagents as needed, and handle settled metal sulfides as needed. The remoteness of the site also
necessitates organized, advanced planning for manpower, consumables, and replacement equipment and supplies.
Cost
Total first year cost for the construction and operation of the bioreactor treatment system operated in gravity flow mode was
$941,248 and $962,471 operated in recirculation mode. The operation and maintenance costs associated with the treatment
system ranged from $15.28 (recirculation) to $16.54 (gravity flow) per 1,000 gallons at an average ARD flow rate of 35.75 liters
per minute. The operational costs were incurred during a research mode of operation. Once the system is optimized an
operations mode will be implemented which will reduce operational labor and reagent costs. Costs for construction and O&M
of the treatment system are dependent on local material, equipment, consumable, and labor costs, required discharge standards,
and hazardous waste classification requirements and disposal costs (if necessary).
Community Acceptance
The bioreactor treatment technology presents minimal to no risk to the public since all system components are located at and
treatment occurs on the Leviathan Mine site, which is a remote, secluded site. Hazardous chemicals used in the treatment system
include sodium hydroxide, ethanol, and for the short term diesel fuel. These chemicals pose the highest risk to the public during
transportation to the site by truck. The diesel generator creates the most noise and air emissions at the site; again, because of the
remoteness of the site, the public is not impacted. Alternative sources of power are being pilot tested at the site to eliminate the
need for the diesel powered generator.
State Acceptance
ARCO, in concurrence with the State of California, selected, constructed, and is currently operating a full-scale bioreactor
treatment system at Leviathan Mine, which indicates the State's acceptance of the technology to treat ARD. The bioreactor
treatment system is the only technology operating year round at the mine site. All other treatment systems at the mine site
shutdown for the winter, requiring long-term storage or discharge of ARD and AMD.
AMD = Acid mine drainage
ARD = Acid rock drainage
ARCO = Atlantic Richfield Company
EPA = U.S. Environmental Protection Agency
TSD = Treatment, storage, and disposal
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SECTION 4
ECONOMIC ANALYSIS
This section presents an economic analysis of the compost-
free bioreactor treatment system used to treat ARD with
chemistry, flow rates, and site logistical issues similar to
those at the Leviathan Mine.
4.1 Introduction
The information presented in this section has been derived
from (1) observations made and experiences gained during
the technology evaluation, (2) data compiled from the
Leviathan Mine Site Engineering Evaluation/Cost Analysis
(EE/CA) (EMC2 2004a), and (3) personal communications
with Dr. Tim Tsukamoto (Tsukamoto 2005b). The costs
associated with designing, constructing, and operating the
bioreactor treatment system in a research mode have been
broken down into the following 10 elements and are
assumed to be appropriate for extrapolation to other mine
sites with similar conditions. Because of the robust system
design and a research mode of operation, a less robust
system and reduced operational labor may be sufficient for
long term operation.
Each cost element is further broken down to document
specific costs associated with each treatment system.
Demobilization is not addressed as the system operates on a
year round basis.
1) Site Preparation
2) Permitting and Regulatory Requirements
3) Capital and Equipment
4) System Startup and Acclimation
5) Consumables and Rentals
6) Labor
7) Utilities
8) Residual Waste Handling and Disposal
9) Analytical Services
10) Maintenance and Modifications
This economic analysis is based primarily on data collected
during the mid-November 2003 through mid-May 2004
evaluation period for the bioreactor treatment system
operated in gravity flow mode and the mid-May 2004
through July 2005 evaluation period for the Bioreactor
treatment system operated in recirculation mode. During
the 2003-2004 evaluation period the bioreactor treatment
system operated in gravity flow mode for twenty-six weeks
(November 14, 2003 to May 11, 2004) and treated 9.24
million liters of ARD from Aspen Seep at an average rate of
31.8 L/min. The bioreactor treatment system also operated
in recirculation mode for sixty-four weeks (May 12, 2004 to
July 31, 2005), treating 22.1 million liters of ARD from
Aspen Seep at an average rate of 34.2 L/min. Costs are
presented for each mode of system operation over their
respective periods of operation. The cost per 1,000 L of
water treated is presented as well as the present worth of the
cumulative variable costs over 5, 15, and 30 years of
treatment. A comparison of treatment costs between the
two modes of system operation will also be discussed.
Section 4.2 presents a cost summary and identifies the major
expenditures for each mode of treatment system operation
(costs are presented in 2005 dollars). As with any cost
analysis, caveats may be applied to specific cost values
based on associated factors, issues and assumptions. The
major factors that can affect estimated costs are discussed in
Section 4.3. Assumptions used in the development of this
economic analysis are identified in Section 4.4. Detailed
analysis of each of the 10 individual cost elements for both
modes of treatment system operation is presented in
Section 4.5.
4.2 Cost Summary
The initial fixed costs to construct bioreactor treatment
system are $836,617 for the treatment system operated in
gravity flow mode, and $864,119 for the treatment system
operated in recirculation mode. Fixed costs consist of site
preparation, permitting, and capital and equipment costs.
Site preparation includes system design, project and
construction management, and preconstruction site work.
Capital and equipment costs include all equipment,
materials, delivery, earthwork, and initial system
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construction. Equipment and materials include reagent
storage tanks, pumps, piping, valves, pond liners, rock
substrate, pH control equipment, automation equipment and
satellite phone for reliable communication at a remote site.
A breakdown of fixed costs for each system is presented in
Section 4.5.
Variable costs to operate the bioreactor treatment system are
$82,155 in gravity flow mode and $75,877 in recirculation
mode. Variable costs consist of system startup and
acclimation, consumable and rentals, labor, utilities, waste
handling and disposal, analytical services, and maintenance
and system modifications. A breakdown of variable costs
for each system is presented in Section 4.5.
The total first year cost to design, construct, and operate the
treatment system; yearly operational costs for each mode of
treatment system operation; and the cumulative 5-year, 15-
year, and 30-year treatment costs for each mode of
treatment system operation are summarized in Table 4-1.
Table 4-1. Cost Summary for Each Mode of Operation
Description
Total First Year Cost
First Year Cost per 1,000 Gallons Treated
Total Variable Costs
Variable Costs per 1,000 Gallons Treated
Cumulative 5-Year Total Variable Cost
(Present Worth at 7% Rate of Return)
Cumulative 1 5- Year Total Variable Cost
(Present Worth at 7% Rate of Return)
Cumulative 30-Year Total Variable Cost
(Present Worth at 7% Rate of Return)
Gravity
Flow
$941,248
$189.54
$82,155
$16.54
$343,834
$764,950
$1,045,005
Recirculation
$962,472
$193.81
$75,877
$15.28
$321,654
$715,681
$977,880
4.3 Factors Affecting Cost Elements
A number of factors can affect the cost of treating ARD
with the bioreactor treatment system. These factors
generally include flow rate, concentration of contaminants,
discharge standards, physical site conditions, geographical
site location, and type and quantity of residuals generated.
Increases in flow rate due to spring melt will slightly raise
operating costs of each system due to proportional increases
in ethanol and sodium hydroxide consumption. Flow rate
increases can also impact fixed costs (number and size of
the bioreactors and settling ponds) when the minimum
system or unit operation HRT is not sufficient to meet
discharge standards.
Operating costs may be slightly impacted by seasonal
increases in contaminant concentration. Increases in metals
concentrations generally require additional HRT to attain
discharge standards. Higher contaminant concentrations
may also change the classification of a residual waste from a
non-hazardous to a hazardous waste, requiring increased
disposal costs. Restrictive discharge standards impact both
fixed and variable costs. System designers and operators
may be forced to extend system and unit operation HRTs
(number and size of bioreactors and settling ponds) and
increase sodium hydroxide dosage to meet stricter discharge
requirements.
Physical site conditions may impact site preparation and
construction costs associated with excavation and
construction of the bioreactors and settling ponds. Cold
climates may limit site access and decrease the activity of
sulfate-reducing bacteria, requiring bioreactors with
extended HRT. The characteristics of the residual solids
produced during treatment may greatly affect disposal costs,
where production of hazardous solids will require off site
disposal at a permitted TSD facility.
4.4 Issues and Assumptions
The following assumptions have been used in the
development of this economic analysis:
• Standard sized tanks are used for ethanol and
sodium hydroxide storage.
• An appropriate staging area is available for
equipment staging, setup and delivery.
• Construction and maintenance of access roads is no
required.
• The treatment system will be operated year round.
• The treatment system will be operated unmanned,
with the exception of a weekly maintenance visit.
• All site power is obtained from a water turbine and
battery system, with a diesel generator as backup.
• Utility water can be obtained on site.
• Non-hazardous sludge will be disposed of at an
off-site landfill or at an existing on-site repository.
• The site is located within 400 kilometers of an off-
site landfill.
• Permitting for the treatment system is not required
because of CERCLA status.
• Treatment goals and discharge standards apply to
those presented in Table 2-4.
• Samples are collected and analyzed weekly to
verify attainment of discharge standards.
4.5 Cost Elements
Each of the 10 cost elements identified in Section 4.1 has
been defined and the associated costs for each treatment
system element presented below. The cost elements for the
each mode of bioreactor treatment system operation, at an
average flow rate of 35.75 L/min, are summarized in Table
4-2. Cost element details for each mode of treatment system
operation are presented in Appendix C.
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Table 4-2. Summary of Cost Elements
Description
Site Preparation
Permitting and Regulatory
Requirements
Compost-Free Bioreactor
Treatment System
Equipment Mobilization/
Demobilization
Pond and Pipe Trench Earthwork
Installation of Pond Liners, Stairs,
and Decant Structures
Installation of Distribution Piping
and Valve Vaults
Placement of Bioreactor Substrate
Erosion Control and
Revegetation/Reseeding
Recirculation Pump and Piping
Water Turbine and Storage Batteries
Reagent Storage and Distribution
Ethanol Storage Tank and
Delivery System
Sodium Hydroxide Storage Tank
and Delivery System
Make up Water Storage Tank and
Delivery System
Reagent Storage Area Fencing
Automation
Remote Monitoring/ Alarm System
pH Controller System
Communications
Total Capital and Equipment Cost
Total Fixed Cost
System Start-up and Acclimation
Consumables and Rentals
Labor
Utilities
Residual Waste Handling and
Disposal
Analytical Services
Maintenance and Modifications
Total 1st Year Variable Costs
Recurring Variable Costs
Periodic Variable Costs
Total 1st Year Cost s
Total 1st Year Costs/l,000-gallons
Total Variable Costs/l,000-gallons
Cumulative 5-Year Total Variable
Costs (Present Worth at 7 Percent
Rate of Return)
Cumulative 15-Year Total Variable
Costs (Present Worth at 7 Percent
Rate of Return)
Cumulative 30-Year Total Variable
Costs (Present Worth at 7 Percent
Rate of Return)
Gravity
Flow
$288,185.95
$0.00
$495,791.00
$73,550.00
$136,442.00
$63,756.00
$149,263.00
$47,173.00
$10,907.00
$0.00
$14,700.00
$35,200.00
$13,400.00
$15,800.00
$2,000.00
$4,000.00
$15,945.00
$9,742.50
$6,202.50
$1,495.00
$548,431.00
$836,616.95
$22,476.00
$26,854.15
$28,198.24
$8,348.00
$14,315.00
$4,440.00
$16,200.00
$104,613.39
$82,155.39
$16,200.00
$941,248.34
$189.54
$16.54
$343,834.00
$764,950.00
$1,045,005.00
Recirculation
$309,568.00
$0.00
$501,911.00
$73,550.00
$136,442.00
$63,756.00
$149,263.00
$47,173.00
$10,907.00
$6,120.00
$14,700.00
$35,200.00
$13,400.00
$15,800.00
$2,000.00
$4,000.00
$15,945.00
$9,742.50
$6,202.50
$1,495.00
$554,551.00
$864,119.00
$22,476.00
$25,046.35
$28,198.24
$8,348.00
$9,844.00
$4,440.00
$21,200.00
$98,352.59
$75,876.59
$21,200.00
$962,471.59
$193.81
$15.28
$321,654.00
$715,681.00
$977,880.00
4.5.1 Site Preparation
Site preparation for the treatment system addresses system
design, construction management, project management, and
preconstruction site work. System design is estimated at 20
percent of the capital and equipment cost for a treatment
system. Construction management is estimated at 15
percent and project management at 10 percent of the capital
and equipment costs for a treatment system (US Army Corp
of Engineers [USAGE] 2000). Preconstruction site work
includes clearing trees and vegetation, chipping cleared
vegetation, debris removal, and topsoil removal and
stockpiling for site restoration purposes. The total site
preparation cost for the bioreactor treatment system
operated in gravity flow mode is $288,186; while the total
site preparation cost for the treatment system operated in
recirculation mode is $309,568. The difference in the costs
is attributed directly to the capital costs associated with the
recirculation system as the majority of the site preparation
costs are a percentage of the capital costs.
4.5.2 Permitting and Regulatory Requirements
Permitting and regulatory costs vary depending on whether
treatment occurs at a CERCLA-lead or a state- or local
authority-lead site. At CERCLA sites such as Leviathan
Mine, removal and remedial actions must be consistent with
environmental laws, ordinances, and regulations, including
Federal, State, and local standards and criteria; however,
permitting is not required.
At a state- or local authority-lead site, a NPDES permit, an
air permit, and a storm water permit will likely be required
as well as additional monitoring, which can increase
permitting and regulatory costs. National Environmental
Policy Act or state equivalent documentation may also be
required for system construction. For a treatment system
similar to those described here, constructed at a state- or
local authority-lead site, permitting and regulatory costs are
estimated to be $50,000.
4.5.3 Capital and Equipment
Capital costs include earthwork and pond construction;
delivery and installation of piping, pond liners, substrate;
and delivery and installation of reagent storage tanks,
pumps, and automation equipment. Equipment and
materials include reagent storage tanks, pumps, piping,
valves, pond liners, rock substrate, pH control equipment,
automation equipment and satellite phone for reliable
communication at a remote site. This analysis assumes that
an area of at least 3,000 to 4,000 square meters is available
for bioreactor and settling pond construction, reagent
storage tanks, support equipment, and staging supplies.
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Total capital expenditures for the bioreactor treatment
system operated in gravity flow mode are $548,431 and
$554,551 for the system operated in recirculation mode.
System construction involves equipment mobilization/
demobilization ($73,550), pond and pipe trench excavation
($136,442), installation of pond liners, stairs, and decant
structures ($63,756), installation of distribution piping and
valve vaults ($149,263), placement of bioreactor rock
substrate ($47,173), erosion control/reseeding ($10,907),
and installation of a water turbine and battery to supply
power ($14,700). Ethanol and sodium hydroxide storage
tanks, delivery systems, and containment are also required
at a cost of $35,200. Automation components of the system
include an automatic pH control system and a SCADA
remote monitoring/alarm system at a cost of approximately
$15,945, including installation. A satellite phone to provide
reliable communication at a remote location is estimated at
$1,495. The cost for construction of the treatment system
operated in gravity flow mode is $495,791. An additional
$6,120 is required for construction of the recirculation
system and is associated with the installation of the
recirculation pump and bypass and return pipelines.
4.5.4 System Startup and Acclimation Costs
System start-up and acclimation includes the labor to setup
pumps and pipes, fill and recirculate ARD within the
system, adjust system hydraulics and reagent dosages, and
optimize the operational HRT to meet discharge standards.
System startup and acclimation occurs once after initial
system construction as the system is design to operate year
round, even in extremely cold weather.
The estimated start up cost for the bioreactor treatment
system is $22,476. It is assumed that start up of the
treatment system will take a two-person crew two weeks to
complete; while acclimation will require only one person
visiting the system 3 days a week over a 10 week period.
Startup and acclimation costs for this system are less than
the active treatment system due to the simplicity of system
design. However, acclimation does require at least 2
months before the system is able to meet discharge
standards.
4.5.5 Consumables and Supplies
Consumables and rentals for the bioreactor treatment system
consist of chemicals and supplies required to treat ARD,
including ethanol and sodium hydroxide, health and safety
equipment, air and water chemistry monitoring equipment,
and storage Connex rental. Total consumable and rental
costs for the bioreactor treatment system are $26,854 for
gravity flow operations and $25,046 for operation in
recirculation mode.
The two largest consumable expenditures are ethanol and
sodium hydroxide. During gravity flow operations, ethanol
was consumed at a rate of approximately 0.43 ml/L of ARD
treated at a cost of $5,655; while sodium hydroxide was
consumed at a rate of approximately 1.1 ml/L of ARD
treated at a cost of $4,963. During operation in recirculation
mode, ethanol was consumed at a rate of approximately 0.5
ml/L of ARD treated at a cost of $6,575; while sodium
hydroxide was consumed at a rate of approximately 0.5
ml/L of ARD treated at a cost of $2,235.
The largest rental cost throughout the year is for a hydrogen
sulfide gas meter and a water quality meter. The meters are
necessary to safely access sampling locations and conduct
internal system monitoring of pH, dissolved oxygen, ORP,
temperature, and the specific conductance of water within
the bioreactors and settling ponds. The annual cost for the
meters, based of four site visits per month is $12,000.
Equipment storage from year to year is also required at a
cost of $3,900. A mobilization and set-up fee is included in
the Connex rental. Purchase of air and water quality meters
as well as a storage Connex should also be considered at a
substantial long term cost savings.
4.5.6 Labor
Labor costs for the long-term O&M of the bioreactor
treatment system include the field personnel necessary to
operate the system, address day-to-day maintenance issues,
collect weekly discharge monitoring samples, monitor unit
operation chemistry and flow rates, adjust reagent dosages,
adjust unit operation HRT, and adjust recirculation rates.
Labor associated with system startup and acclimation is
included in Section 4.5.4.
Due to the passive nature of the treatment system, minimal
O&M labor is necessary in comparison to an active
treatment system. It is assumed that long-term O&M of the
treatment system will require only one person visiting the
system 1 day a week over the course of a year. The field
technician labor cost for O&M of the bioreactor treatment
system is $23,375. An additional labor cost of $4,823 is
required for project management and administrative support.
4.5.7 Utilities
Due to the remote nature of the site, utilities are not
available. A water turbine and storage battery may be used
to provide power. Utility costs generally consist of the cost
to lease a 3kW backup generator, generator fuel, seasonal
portable toilet rental, and satellite phone service. Water is
gravity fed to the treatment system from upper Aspen Creek
via the water turbine outfall. SCADA service through a
satellite uplink may also be used to monitor water chemistry
and control dosing of ethanol and sodium hydroxide to the
54
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bioreactor treatment system. Total utility costs to support
operation of the treatment system in either mode are $8,348.
4.5.8 Residual Waste Handling and
Disposal
The bioreactor treatment system produces metal sulfide
sludge. Solids accumulation in the settling ponds occur at a
slow enough rate to require removal once every two to three
years; however, it is removed annually to allow extended
HRT. Removal of sludge from the settling ponds and bag
filtration is performed in late summer to allow time for
profiling and disposal. The cost to dewater the sludge from
the settling ponds, using eight to ten bag filters, is
approximately $3,795. The bioreactor treatment system
operated in gravity flow mode generates approximately
8 dry tons (40 wet tons at 80 percent moisture content) of
bag filter solids over the course of a year, while
recirculation mode generates only 4.6 dry tons (23 wet tons
at 80 percent moisture content)
Bag filter solids were evaluated for hazardous waste
characteristics. The bag filter solids were determined to be
non-hazardous. The solids may be disposed of off-site in a
non-hazardous waste repository at a total cost of $10,520 for
gravity flow operations and $6,049 for recirculation
operations. Non-hazardous solid waste may also be
disposed of on site after a designated repository has been
identified.
4.5.9 Analytical Services
Analytical services consist of weekly sampling of the
bioreactor treatment system to verify compliance with
discharge standards. One effluent grab sample is collected
each week and analyzed for metals using EPA Methods
601 OB and 7470 to demonstrate compliance with discharge
standards. The cost for weekly analytical services is $4,160
for the bioreactor treatment system.
A grab sample of bag filter solids is also collected to
support waste characterization, profiling, and disposal.
Each grab solid sample is analyzed for metals using EPA
Methods 601 OB and 7471 and leachable metals using the
EPA Methods 1311, 6010B, and 7470 for comparison to
Federal RCRA and TCLP criteria and California DI
WET/EPA Method 6010B for comparison to State TTLC
and STLC criteria. Analysis of one composite bag filter
solids sample generated during solids filtration is required at
a cost of $280.
4.5.10 Maintenance and Modifications
Maintenance and modifications costs include regular
equipment replacement due to wear and tear. Equipment
expected to require replacement includes reagent pumps and
delivery lines, recirculation pump, water turbine, and
storage batteries.
Reagent pumps and delivery lines ($2,000) should be
replaced every two years. The recirculation pump ($5,000)
and water turbine storage battery ($5,200) may require
replacement every five years. It is estimated that the water
turbine ($9,000) may require replacement on a 20 year
schedule. The annualized equipment replacement cost for
the bioreactor treatment system operated in gravity flow and
recirculation modes is approximately $2,490 and $3,490,
respectively.
55
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SECTION 5
DATA QUALITY REVIEW
SITE demonstration samples were collected in accordance
with the 2003 TEP/QAPP (Tetra Tech 2003). As part of the
quality assurance/quality control (QA/QC) requirements
specified in the TEP/QAPP, any deviations from the sampling
plan, such as missed sampling events, changes in sampling
locations, or changes in analytical methods, were documented
throughout the duration of the demonstration and are
presented in Section 5.1. Documentation of these deviations is
important because of the potential effects they have on data
quality and on the ability of the data to meet the project
objectives.
As part of the QA/QC data review, sample delivery groups
(SDG) received from the laboratory underwent data validation
through a third-party validator to ensure that the data
generated is of a quality sufficient to meet project objectives.
As specified in the TEP/QAPP, data packages underwent 10
percent full validation in accordance with EPA validation
guidance (EPA 1995). A summary of the data validation
performed on the bioreactor treatment technology SITE
demonstration data is presented in Section 5.2.
5.1 Deviations from TEP/QAPP
Due to various operating issues, several changes were required
in the sampling of the bioreactor treatment system during the
SITE demonstration. Deviations from the TEP/QAPP related
to each mode of treatment system operation were documented
throughout the duration of the SITE demonstration and are
presented below.
• The sample frequency was reduced from every two
weeks to once a month, at the direction of the EPA
task order manager (TOM), to extended the
demonstration period over two successive winters of
system operation.
• Began analysis of samples collected from the influent
(S3) and effluent (S4) of Bioreactor No. 1 for sulfate,
TSS, TDS, and alkalinity after system acclimation
period. The data will be used to allow independent
evaluation of each bioreactor, rather than a
combination of the two bioreactors.
Began analysis of samples collected from the influent
(S5) and effluent (S7) of the settling ponds for sulfate
at the start of the demonstration to determine if
additional sulfate reduction is occurring in the
settling and flushing ponds.
Began analysis of samples collected from the influent
(S5) and effluent (S7) of the settling ponds for
alkalinity after system acclimation to evaluate the
source of alkalinity observed in system effluent.
Collected an unsettled solids slurry sample from
settling pond (S14) to evaluate changes in settling
pond chemistry after reconfiguration of the system
for recirculation operation.
Collected a solids composite sample (SI5) from one
of the bag filters used to dewater sludge from the
settling pond to assess the content and teachability of
metals in dewatered treatment system sludge. The
solids sample was analyzed for total metals and
metals after TCLP extraction, SPLP extraction, and
California DI WET extraction. The solids sample
was also analyzed for total solids and percent
moisture in order to estimate the likely increase in
metals concentration after drying.
Samples were not collected from the settling pond
outfall (S6) due to lack of accessibility. The system
operator discharged directly from the settling pond to
the flushing pond to allow extended settling.
Therefore, effluent from the flushing pond (S7)
represents the treatment effectiveness of both ponds.
Aqueous samples were not collected from the
flushing pond (S11) because the extended HRT of the
pond limited changes in pond chemistry. In addition,
the pond surface was frozen over for at least a one-
third of the demonstration period. Instead, the pond
effluent (S7) was used to represent changes in pond
chemistry.
56
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• A sample was not collected at the system point of
discharge on February 3, 2005 due to lack of
accessibility (iced over), instead the effluent from the
flushing pond (S7) was used to represent the system
effluent for the day.
• Samples of flushed metal sulfide precipitate were not
collected from the two bioreactors (S8 and S9)
because not enough solids have built up in the
bioreactors to require flushing.
5.2 Summary of Data Validation and PARCC
Criteria Evaluation
The critical data quality parameters evaluated during data
validation include precision, accuracy, representativeness,
completeness, and comparability (PARCC). Evaluation of
these critical parameters provides insight on the quality of the
data and is essential in determining whether the data is of
sufficient quality to meet project objectives. A summary of
the data validation for the SITE demonstration data and an
evaluation of the PARCC parameters for the primary target
analytes are presented below.
Based on data validation, no metals results were rejected in the
samples analyzed. However, some metals data were qualified
as estimated based on other QC issues. QC issues resulting in
qualified data typically consisted of problems with calibration
and method blank contamination, inductively coupled plasma
(ICP) interference check sample analysis, percent recovery
and relative percent difference (RPD) values outside of
acceptable values, and ICP serial dilution problems. An
evaluation of the PARCC parameters follows.
Precision: Precision for the SITE demonstration data was
evaluated through the analysis of matrix duplicates (MD)
samples for metals. The precision goal for MD samples was
established at less than or equal to 25 percent RPD. Over the
duration of the SITE demonstration, a total of 13 aqueous
samples and two sludge samples were collected from the
treatment system and analyzed in duplicate. Where one or
both metals results in a duplicate pair were below the practical
quantitation limit (PQL) or not detected, the RPD was not
calculated. Out of the five primary target metals and the five
secondary water quality indicator metals, none of the metals
exceeded the 25 percent RPD criteria. Corresponding metals
data for associated samples within each SDG were qualified as
estimated based on duplicate precision problems; however, no
data was rejected.
Accuracy: Accuracy for the SITE demonstration data was
evaluated through the analysis of matrix spike (MS) samples
for the metals analyses. The accuracy goal for MS samples
was established at 75 to 125 percent for percent recovery.
Over the duration of the SITE demonstration, a total of 13
aqueous samples were collected from the treatment system
and analyzed as MS samples. In addition, two sludge samples
and six metals leachate samples were analyzed as MS
samples. Potassium in one water sample and in one leachate
sample was qualified based on MS recovery problems.
Representativeness: Representativeness expresses the degree
to which sample data accurately and precisely represent the
characteristics of a population, parameter variations at a
sampling point, or an environmental condition that they are
intended to represent. Representativeness is a qualitative
parameter; therefore, no specific criteria must be met.
Representative data were obtained during the SITE
demonstration through selection of proper sampling locations
and analytical methods based on the project objectives and
sampling program described in Section 2.3. As specified in
the TEP/QAPP, proper collection and handling of samples
avoided cross contamination and minimized analyte losses.
The application of standardized laboratory procedures also
facilitated generation of representative data.
To aid in the evaluation of sample representativeness,
laboratory-required method blank samples were analyzed and
evaluated for the presence of contaminants. Sample data
determined to be non-representative by comparison with
method blank data was qualified, as described earlier in this
section. The data collected during the SITE demonstration are
deemed representative of the chemical concentrations,
physical properties, and other non-analytical parameters that
were being sampled or documented. No metals data were
rejected.
Completeness: Completeness is a measure of the percentage
of project-specific data deemed valid. Valid data are obtained
when samples are collected and analyzed in accordance with
QC procedures outlined in the TEP/QAPP and when none of
the QC criteria that affect data usability are significantly
exceeded. Other factors not related to the validity of the data
can also affect completeness, such as lost or broken samples,
missed sampling events, or operational changes by the system
operator.
Due to the time required to acclimate the bioreactor treatment
system in cold weather conditions, the original sampling
frequency of twice a month during the acclimation period was
not followed. Instead, a monthly sampling frequency was
followed toward the end of the acclimation period. A monthly
sampling frequency was followed for the duration of the
demonstration, unless the site was inaccessible due to winter
storms. A monthly sampling frequency was selected to
provide a long-term evaluation of the treatment system over
two winters.
From November 2003 through mid-May 2004, the bioreactor
treatment system was evaluated based on the original system
configuration. In mid-May 2004, UNR and ARCO modified
the operation of the system to include introduction of system
influent to the settling pond, contact of ARD influent with
57
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sulfide-rich bioreactor effluent in the settling pond, and
recirculation of settling pond effluent to the head of Bioreactor
No.l. The treatment system was operated in recirculation
mode from mid-May 2004 through the end of the
demonstration period in July 2005.
Evaluation of the system during recirculation operation
represented a significant departure from the TEP/QAPP. The
original sample design was reviewed and retained and only
modified where a sampling location was no longer valid or
duplicative. The monthly evaluation of the treatment system
in both modes of operation (gravity-flow and recirculation),
though a modification in scope and frequency, was also fully
achieved.
As specified in the TEP/QAPP, the project completeness goal
for the SITE demonstration was 90 percent. Based on an
evaluation of the data that was collected and analyzed and
other documentation, completeness for the project was greater
than 99 percent. Deviations from the TEP/QAPP due to
unplanned changes in system operation by the system operator
did not impact the validity of the data. Instead, the unplanned
changes provided an opportunity to evaluate different modes
of system operation and system response to changes in flow
rate and HRT.
Comparability: The comparability objective determines
whether analytical conditions are sufficiently uniform
throughout the duration of the project to ensure that reported
data are consistent. For the SITE demonstration, the
generation of uniform data was ensured through adherence of
the contracted laboratory to specified analytical methods, QC
criteria, standardized units of measure, and standardized
electronic deliverables in accordance with the TEP/QAPP.
Comparability for the SITE demonstration data was also
ensured through third party validation. As a result of these
efforts, no data comparability issues were documented by the
project team for this project.
58
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SECTION 6
TECHNOLOGY STATUS
The technology associated with the compost-free bioreactor
treatment system is not proprietary, nor are proprietary
reagents or equipment required for system operation. The
treatment system has been demonstrated at full-scale and is
currently operational at Leviathan Mine. The treatment
system is scalable, requiring an increase in the size or number
of bioreactors and settling ponds to achieve the required unit
operation and system HRT necessary for sulfide generation,
metal-sulfide contact, and precipitate settling. The bioreactor
treatment system at Leviathan Mine has been operated at
flows ranging from 25 to 91 L/min.
The treatment system is undergoing continuous refinement
and optimization to reduce the quantity of ethanol and base
required, evaluate alternate sources of base addition, reduce
recirculation rates, improve attainment of discharge standards
for iron and selenium, and improve solids handling and
dewatering processes. The power required for recirculation of
water to the head of the system is currently provided by a
generator. In 2006, alternative methods of power generation
will be investigated. Because of the success of compost-free
bioreactor treatment system at Leviathan Mine, ARCO will
continue to use this technology to treat ARD at the Aspen
Seep and are also evaluating the potential effectiveness,
implementability, and costs for treatment of other ARD
sources at the mine site.
Application of the technology to other ARD-impacted sites
does not require a pilot-scale system because the uncertainties
related to carbon availability and sulfate reduction efficiency,
matrix compaction, and solids flushing associated with
compost and wood chip matrices are essentially eliminated. A
simple bench test can be used to optimize the ethanol dose
necessary to reduce sulfate, to optimize the base type and dose
required to neutralize acidity, and to determine the volume of
metal sulfide precipitate that will be generated.
59
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REFERENCES CITED
Analyze-It. 2004. Analyze-It Statistical Software.
Version 1.71. September. Available on-line:
http://www.analyse-it.com/
California Regional Water Quality Control Board - Lahontan
Region (RWQCB). 1995. "Leviathan Mine 5-year Work
Plan." July.
EMC2. 2004. "Engineering Evaluation/Cost Analysis for
Leviathan Mine." March 31, 2004.
State of California. 2004. "Waste Extraction Test."
California Code of Regulations. Title 22, Division 4-
Environmental Health. July.
TetraTech. 2003. "2003 Technology Evaluation Plan/
Quality Assurance Project Plan, Leviathan Mine
Superfund Site." Alpine County, California. August.
Tetra Tech. 2006. "Draft Technology Evaluation Report Data
Summary, Demonstration of Compost-Free Bioreactor
Treatment Technology, Leviathan Mine Superfund Site."
Alpine County, California. January.
Tsukamoto, Tim. 2004. "Data Summary Report for
Bioreactors at the Leviathan Mine Aspen Seep 2003."
April.
Tsukamoto, Tim. 2005a. "Data Summary Report for
Bioreactors at the Leviathan Mine Aspen Seep 2004."
August.
Tsukamoto, Tim. 2005b. Personal communications regarding
bioreactor treatment system construction and operating
costs. November.
U.S. Army Corp of Engineers (USACE). 2000. A Guide to
Developing and Documenting Cost Estimates during the
Feasibility Study. July 2000.
U.S. Environmental Protection Agency (EPA). 1995. "CLP
SOW for Inorganics Analysis, Multi-Media,
Multi-Concentration." Document Number ILM04.0.
EPA. 1997. Test Methods for Evaluating Solid
Waste/Chemical Methods, Laboratory, Volume 1A
through 1C, and Field Manual, Volume 2. SW-846,
Third Edition (Revision III). Office of Solid Waste and
Emergency Response.
EPA. 2000. "Guidance for Data Quality Assessment:
Practical Methods for Data Analysis." EPA QA/G-9.
EPA/600/R-96/084.
EPA. 2002. "Remedial Action Memorandum: Request for
Approval of Removal Action at the Leviathan Mine,
Alpine County, CA." From: Kevin Mayer, RPM, Site
Cleanup Branch, EPA Region 9, To: Keith Takata,
Director, Superfund Division, USEPA. July 18.
EPA. 2004. ProUCL Version 3.0. EPA Statistical Program
Package. April. Available on-line:
http://www.epa.gov/nerlesdl/tsc/form.htm
60
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APPENDIX A
SAMPLE COLLECTION AND ANALYSIS TABLES
61
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Table A-l. Sample Register for the Compost-Free Bioreactor Treatment System, Gravity Flow Operations
Sample ID
3-AW-01-5-S01-W-C
3-AW-01-5-S01-W-C-F
3-AW-01-5-S02-W-C
3-AW-01-5-S02-W-C-F
3-AW-01-5-S03-W-C
3-AW-01-5-S03-W-C-F
3-AW-01-5-S04-W-C
3-AW-01-5-S04-W-C-F
3-AW-01-5-S05-W-C
3-AW-01-5-S05-W-C-F
3-AW-01-5-S07-W-C
3-AW-01-5-S07-W-C-F
3-AW-03-2-S01-W-C
3-AW-03-2-S01-W-C-F
3-AW-03-2-S02-W-C
3-AW-03-2-S02-W-C-F
3-AW-03-2-S03-W-C
3-AW-03-2-S03-W-C-F
3-AW-03-2-S04-W-C
3-AW-03-2-S04-W-C-F
3-AW-03-2-S05-W-C
3-AW-03-2-S05-W-C-F
3-AW-03-2-S07-W-C
3-AW-03-2-S07-W-C-F
AW-1/29/04-S1-W-C
AW-1/29/04-S1-W-C-F
AW-1/29/04-S2-W-C
AW-1/29/04-S2-W-C-F
AW-1/29/04-S3-W-C
AW-1/29/04-S3-W-C-F
AW-1/29/04-S4-W-C
Date
11/14/2003
11/14/2003
11/14/2003
11/14/2003
11/14/2003
11/14/2003
11/14/2003
11/14/2003
11/14/2003
11/14/2003
11/14/2003
11/14/2003
1 1/25/2003
11/25/2003
1 1/25/2003
11/25/2003
11/25/2003
11/25/2003
11/25/2003
11/25/2003
11/25/2003
11/25/2003
1 1/25/2003
1 1/25/2003
1/29/2004
1/29/2004
1/29/2004
1/29/2004
1/29/2004
1/29/2004
1/29/2004
Location
System Influent at Weir
System Influent at Weir
System Effluent
System Effluent
Bioreactor 1 Influent
Bioreactor 1 Influent
Bioreactor 1 Effluent
Bioreactor 1 Effluent
Bioreactor 2 Effluent
Bioreactor 2 Effluent
Pond 4 Effluent Pipe
Pond 4 Effluent Pipe
System Influent at Weir
System Influent at Weir
System Effluent
System Effluent
Bioreactor 1 Influent
Bioreactor 1 Influent
Bioreactor 1 Effluent
Bioreactor 1 Effluent
Bioreactor 2 Effluent
Bioreactor 2 Effluent
Pond 4 Effluent Pipe
Pond 4 Effluent Pipe
System Influent at Weir
System Influent at Weir
System Effluent
System Effluent
Bioreactor 1 Influent
Bioreactor 1 Influent
Bioreactor 1 Effluent
Filtered?
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Project
Objective
PI, P2, SGI, SG2, SG6
PI, P2
PI, P2, SGI, SG2, SG3, SG6
P1,P2
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
PI, P2, SGI, SG2, SG6
PI, P2
PI, P2, SGI, SG2, SG3, SG6
P1,P2
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
P1,P2, SGI, SG2, SG6
P1,P2
PI, P2, SGI, SG2, SG3, SG6
PI, P2
SGI, SG6
SGI, SG6
SGI, SG6
Total
Metals
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Sulfate
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Alkalinity
X
X
X
X
X
X
X
TSS
X
X
X
X
X
X
X
X
X
X
TDS
X
X
X
X
X
X
X
X
X
X
Comments
MS/MSD
MS/MSD
MS/MSD
62
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Table A-l. Sample Register for the Compost-Free Bioreactor Treatment System, Gravity Flow Operations (continued)
Sample ID
AW-1/29/04-S4-W-C-F
AW-1/29/04-S5-W-C
AW-1/29/04-S5-W-C-F
AW-1/29/04-S7-W-C
AW-1/29/04-S7-W-C-F
4-AW-2/19/04-S1-W-C
4-AW-2/19/04-S1-W-C-F
4-AW-2/19/04-S2-W-C
4-AW-2/19/04-S2-W-C-F
4-AW-2/19/04-S3-W-C
4-AW-2/19/04-S3-W-C-F
4-AW-2/19/04-S4-W-C
4-AW-2/19/04-S4-W-C-F
4-AW-2/19/04-S5-W-C
4-AW-2/19/04-S5-W-C-F
4-AW-2/19/04-S7-W-C
4-AW-2/19/04-S7-W-C-F
4-AW-3/24/04-S1-W-C
4-AW-3/24/04-S1-W-C-F
4-AW-3/24/04-S2-W-C
4-AW-3/24/04-S2-W-C-F
4-AW-3/24/04-S3-W-C
4-AW-3/24/04-S3-W-C-F
4-AW-3/24/04-S4-W-C
4-AW-3/24/04-S4-W-C-F
4-AW-3/24/04-S5-W-C
4-AW-3/24/04-S5-W-C-F
4-AW-3/24/04-S7-W-C
4-AW-3/24/04-S7-W-C-F
4-AW-4/29/04-S1-W-C
4-AW-4/29/04-S 1-W-C-F
Date
1/29/2004
1/29/2004
1/29/2004
1/29/2004
1/29/2004
2/19/2004
2/19/2004
2/19/2004
2/19/2004
2/19/2004
2/19/2004
2/19/2004
2/19/2004
2/19/2004
2/19/2004
2/19/2004
2/19/2004
3/24/2004
3/24/2004
3/24/2004
3/24/2004
3/24/2004
3/24/2004
3/24/2004
3/24/2004
3/24/2004
3/24/2004
3/24/2004
3/24/2004
4/29/2004
4/29/2004
Location
Bioreactor 1 Effluent
Bioreactor 2 Effluent
Bioreactor 2 Effluent
Pond 4 Effluent Pipe
Pond 4 Effluent Pipe
System Influent at Weir
System Influent at Weir
System Effluent
System Effluent
Bioreactor 1 Influent
Bioreactor 1 Influent
Bioreactor 1 Effluent
Bioreactor 1 Effluent
Bioreactor 2 Effluent
Bioreactor 2 Effluent
Pond 4 Effluent Pipe
Pond 4 Effluent Pipe
System Influent at Weir
System Influent at Weir
System Effluent
System Effluent
Bioreactor 1 Influent
Bioreactor 1 Influent
Bioreactor 1 Effluent
Bioreactor 1 Effluent
Bioreactor 2 Effluent
Bioreactor 2 Effluent
Pond 4 Effluent Pipe
Pond 4 Effluent Pipe
System Influent at Weir
System Influent at Weir
Filtered?
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
Project
Objective
SGI, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
P1,P2, SGI, SG2, SG6
PI, P2
PI, P2, SGI, SG2, SG3, SG6
PI, P2
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
P1,P2, SGI, SG2, SG6
PI, P2
PI, P2, SGI, SG2, SG3, SG6
PI, P2
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
P1,P2, SGI, SG2, SG6
PI, P2
Total
Metals
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Sulfate
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Alkalinity
X
X
X
X
X
X
X
X
X
X
X
X
X
TSS
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
TDS
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Comments
MS/MSD
MS/MSD
63
-------
Table A-l. Sample Register for the Compost-Free Bioreactor Treatment System, Gravity Flow Operations (continued)
Sample ID
4-AW-4/29/04-S2-W-C
4-AW-4/29/04-S2-W-C-F
4-AW-4/29/04-S3-W-C
4-AW-4/29/04-S3-W-C-F
4-AW-4/29/04-S4-W-C
4-AW-4/29/04-S4-W-C-F
4-AW-4/29/04-S5-W-C
4-AW-4/29/04-S5-W-C-F
4-AW-4/29/04-S7-W-C
4-AW-4/29/04-S7-W-C-F
Date
4/29/2004
4/29/2004
4/29/2004
4/29/2004
4/29/2004
4/29/2004
4/29/2004
4/29/2004
4/29/2004
4/29/2004
Location
System Effluent
System Effluent
Bioreactor 1 Influent
Bioreactor 1 Influent
Bioreactor 1 Effluent
Bioreactor 1 Effluent
Bioreactor 2 Effluent
Bioreactor 2 Effluent
Pond 4 Effluent Pipe
Pond 4 Effluent Pipe
Filtered?
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
Project
Objective
PI, P2, SGI, SG2, SG3, SG6
PI, P2
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
Total
Metals
X
X
X
X
X
X
X
X
X
X
Sulfate
X
X
X
X
X
Alkalinity
X
X
X
X
X
TSS
X
X
X
X
X
TDS
X
X
X
X
X
Comments
MS/MSD
MS/MSD=Matrix spike/matrix duplicate TDS=Total dissolved solids TSS=Total suspended solids
64
-------
Table A-2. Sample Register for the Compost-Free Bioreactor Treatment System, Recirculation Operations
Sample ID
AW-6/14/04-S14-W-G
AW-6/14/04-S14-W-G-F
AW-6/14/04-S1-W-C
AW-6/14/04-S1-W-C-F
AW-6/14/04-S2-W-C
AW-6/14/04-S2-W-C-F
AW-6/14/04-S3-W-C
AW-6/14/04-S3-W-C-F
AW-6/14/04-S4-W-C
AW-6/14/04-S4-W-C-F
AW-6/14/04-S5-W-C
AW-6/14/04-S5-W-C-F
AW-6/14/04-S7-W-C
AW-6/14/04-S7-W-C-F
AW-8/19/04-S1-W-C
AW-8/19/04-S1-W-C-F
AW-8/19/04-S2-W-C
AW-8/19/04-S2-W-C-F
AW-8/19/04-S3-W-C
AW-8/19/04-S3-W-C-F
AW-8/19/04-S4-W-C
AW-8/19/04-S4-W-C-F
AW-8/19/04-S5-W-C
AW-8/19/04-S5-W-C-F
AW-8/19/04-S7-W-C
AW-8/19/04-S7-W-C-F
AW-12/3/04-S1-W-C
AW-12/3/04-S1-W-C-F
AW-12/3/04-S2-W-C
AW-12/3/04-S2-W-C-F
AW-12/3/04-S3-W-C
Date
6/16/2004
6/16/2004
6/16/2004
6/16/2004
6/16/2004
6/16/2004
6/16/2004
6/16/2004
6/16/2004
6/16/2004
6/16/2004
6/16/2004
6/16/2004
6/16/2004
8/19/2004
8/19/2004
8/19/2004
8/19/2004
8/19/2004
8/19/2004
8/19/2004
8/19/2004
8/19/2004
8/19/2004
8/19/2004
8/19/2004
12/3/2004
12/3/2004
12/3/2004
12/3/2004
12/3/2004
Location
Pond 3
Pond 3
System Influent at Weir
System Influent at Weir
System Effluent
System Effluent
Bioreactor 1 Influent
Bioreactor 1 Influent
Bioreactor 1 Effluent
Bioreactor 1 Effluent
Bioreactor 2 Effluent
Bioreactor 2 Effluent
Pond 4 Effluent Pipe
Pond 4 Effluent Pipe
System Influent at Weir
System Influent at Weir
System Effluent
System Effluent
Bioreactor 1 Influent
Bioreactor 1 Influent
Bioreactor 1 Effluent
Bioreactor 1 Effluent
Bioreactor 2 Effluent
Bioreactor 2 Effluent
Pond 4 Effluent Pipe
Pond 4 Effluent Pipe
System Influent at Weir
System Influent at Weir
System Effluent
System Effluent
Bioreactor 1 Influent
Filtered?
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Project
Objective
SG2, SG3
SG2, SG3
P1,P2, SGI, SG2, SG6
P1,P2
PI, P2, SGI, SG2, SG3, SG6
PI, P2
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
P1,P2, SGI, SG2, SG6
P1,P2
PI, P2, SGI, SG2, SG3, SG6
PI, P2
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
P1,P2, SGI, SG2, SG6
PI, P2
PI, P2, SGI, SG2, SG3, SG6
P1,P2
SGI, SG6
Total
Metals
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Sulfate
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Alkalinity
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
TSS
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
TDS
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Comments
MS/MSD
MS/MSD
65
-------
Table A-2. Sample Register for the Compost-Free Bioreactor Treatment System, Recirculation Operations (continued)
Sample ID
AW-12/3/04-S3-W-C-F
AW- 1 2/3/04- S4-W-C
AW-12/3/04-S4-W-C-F
AW-12/3/04-S5-W-C
AW-12/3/04-S5-W-C-F
AW-12/3/04-S7-W-C
AW-12/3/04-S7-W-C-F
AW-2/3/05-S1-W-C
AW-2/3/05-S1-W-C-F
AW-2/3/05-S3-W-C
AW-2/3/05-S3-W-C-F
AW-2/3/05-S4-W-C
AW-2/3/05-S4-W-C-F
AW-2/3/05-S5-W-C
AW-2/3/05-S5-W-C-F
AW-2/3/05-S7-W-C
AW-2/3/05-S7-W-C-F
AW-3/17/05-S1-W-C
AW-3/17/05-S1-W-C-F
AW-3/17/05-S2-W-C
AW-3/17/05-S2-W-C-F
AW-3/17/05-S3-W-C
AW-3/17/05-S3-W-C-F
AW-3/17/05-S4-W-C
AW-3/17/05-S4-W-C-F
AW-3/17/05-S5-W-C
AW-3/17/05-S5-W-C-F
AW-3/17/05-S7-W-C
AW-3/17/05-S7-W-C-F
AW-4/27/05-S1-W-C
Date
12/3/2004
12/3/2004
12/3/2004
12/3/2004
12/3/2004
12/3/2004
12/3/2004
2/3/2005
2/3/2005
2/3/2005
2/3/2005
2/3/2005
2/3/2005
2/3/2005
2/3/2005
2/3/2005
2/3/2005
3/17/2005
3/17/2005
3/17/2005
3/17/2005
3/17/2005
3/17/2005
3/17/2005
3/17/2005
3/17/2005
3/17/2005
3/17/2005
3/17/2005
4/27/2005
Location
Bioreactor 1 Influent
Bioreactor 1 Effluent
Bioreactor 1 Effluent
Bioreactor 2 Effluent
Bioreactor 2 Effluent
Pond 4 Effluent Pipe
Pond 4 Effluent Pipe
System Influent at Weir
System Influent at Weir
Bioreactor 1 Influent
Bioreactor 1 Influent
Bioreactor 1 Effluent
Bioreactor 1 Effluent
Bioreactor 2 Effluent
Bioreactor 2 Effluent
Pond 4 Effluent Pipe
Pond 4 Effluent Pipe
System Influent at Weir
System Influent at Weir
System Effluent
System Effluent
Bioreactor 1 Influent
Bioreactor 1 Influent
Bioreactor 1 Effluent
Bioreactor 1 Effluent
Bioreactor 2 Effluent
Bioreactor 2 Effluent
Pond 4 Effluent Pipe
Pond 4 Effluent Pipe
System Influent at Weir
Filtered?
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Project
Objective
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
P1,P2, SGI, SG2, SG6
PI, P2
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG3, SG6
SGI, SG3, SG6
PI, P2, SGI, SG2, SG3, SG6
P1,P2
PI, P2, SGI, SG2, SG6
P1,P2
PI, P2, SGI, SG2, SG3, SG6
PI, P2
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
PI, P2, SGI, SG2, SG6
Total
Metals
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Sulfate
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Alkalinity
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
TSS
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
TDS
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Comments
MS/MSD
Effluent, S2 iced
over, MS/MSD
MS/MSD
MS/MSD
66
-------
Table A-2. Sample Register for the Compost-Free Bioreactor Treatment System, Recirculation Operations (continued)
Sample ID
AW-4/27/05-S1-W-C-F
AW-4/27/05-S2-W-C
AW-4/27/05-S2-W-C-F
AW-4/27/05-S3-W-C
AW-4/27/05-S3-W-C-F
AW-4/27/05-S4-W-C
AW-4/27/05-S4-W-C-F
AW-4/27/05-S5-W-C
AW-4/27/05-S5-W-C-F
AW-4/27/05-S7-W-C
AW-4/27/05-S7-W-C-F
AW-6/2/05-S1-W-C
AW-6/2/05-S1-W-C-F
AW-6/2/05-S2-W-C
AW-6/2/05-S2-W-C-F
AW-6/2/05-S3-W-C
AW-6/2/05-S3-W-C-F
AW-6/2/05-S4-W-C
AW-6/2/05-S4-W-C-F
AW-6/2/05-S5-W-C
AW-6/2/05-S5-W-C-F
AW-6/2/05-S7-W-C
AW-6/2/05-S7-W-C-F
Date
4/27/2005
4/27/2005
4/27/2005
4/27/2005
4/27/2005
4/27/2005
4/27/2005
4/27/2005
4/27/2005
4/27/2005
4/27/2005
6/2/2005
6/2/2005
6/2/2005
6/2/2005
6/2/2005
6/2/2005
6/2/2005
6/2/2005
6/2/2005
6/2/2005
6/2/2005
6/2/2005
Location
System Influent at Weir
System Effluent
System Effluent
Bioreactor 1 Influent
Bioreactor 1 Influent
Bioreactor 1 Effluent
Bioreactor 1 Effluent
Bioreactor 2 Effluent
Bioreactor 2 Effluent
Pond 4 Effluent Pipe
Pond 4 Effluent Pipe
System Influent at Weir
System Influent at Weir
System Effluent
System Effluent
Bioreactor 1 Influent
Bioreactor 1 Influent
Bioreactor 1 Effluent
Bioreactor 1 Effluent
Bioreactor 2 Effluent
Bioreactor 2 Effluent
Pond 4 Effluent Pipe
Pond 4 Effluent Pipe
Filtered?
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
Project
Objective
P1,P2
PI, P2, SGI, SG2, SG3, SG6
PI, P2
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
P1,P2, SGI, SG2, SG6
PI, P2
PI, P2, SGI, SG2, SG3, SG6
P1,P2
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
SGI, SG3, SG6
Total
Metals
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Sulfate
X
X
X
X
X
X
X
X
X
X
X
Alkalinity
X
X
X
X
X
X
X
X
X
X
X
TSS
X
X
X
X
X
X
X
X
X
X
X
TDS
X
X
X
X
X
X
X
X
X
X
X
Comments
MS/MSD
MS/MSD=Matrix spike/matrix duplicate TDS=Total dissolved solids TSS=Total suspended solids
67
-------
Table A-3. Sample Register for the Compost-Free Bioreactor Treatment System, Solids for Both Modes of Operation
Sample ID
AW-7/13/05-S10-S-C
AW-7/13/05-S11-S-C
AW-7/13/05-S12-S-C
AW-7/13/05-S13-S-C
AW-9/29/05-S15-S-G
Date
7/13/2005
7/13/2005
7/13/2005
7/13/2005
9/29/2005
Location
Pond 3 sludge
Pond 4 sludge
Aeration Channel sludge
Pretreatment Pond sludge
Bag Filter Solids
Filtered?
___
___
—
___
—
Project
Objective
SG4
SG4
SG4
SG4
SG4
SPLP
Metals
X
X
X
X
X
TCLP
Metals
X
X
X
X
X
WET
Metals
X
X
X
X
X
Total
Metals
X
X
X
X
X
Percent
Moisture
X
X
X
X
X
Comments
MS/MSD
MS/MSD
MS/MSD=Matrix spike/matrix duplicate TCLP=Toxicity characteristic leaching procedure
SPLP=Synthetic precipitation and leaching procedure WET= Waste extraction test
68
-------
APPENDIX B
DATA USED TO EVALUATE PROJECT PRIMARY OBJECTIVES
69
-------
Table B-l. Data Used to Evaluate Project Objectives for the Bioreactor Treatment System, Gravity Flow Operations
Sample Number (1)
3-AW-01-5-SOX-W-C-F
3-AW-03-2-SOX-W-C-F
AW-l/29/04-SX-W-C-F
4-AW-2/19/04-SX-W-C-F
4-AW-3/24/04-SX-W-C-F
4-AW-4/29/04-SX-W-C-F
3-AW-01-5-SOX-W-C-F
3-AW-03-2-SOX-W-C-F
AW-l/29/04-SX-W-C-F
4-AW-2/19/04-SX-W-C-F
4-AW-3/24/04-SX-W-C-F
4-AW-4/29/04-SX-W-C-F
3-AW-01-5-SOX-W-C-F
3-AW-03-2-SOX-W-C-F
AW-l/29/04-SX-W-C-F
4-AW-2/19/04-SX-W-C-F
4-AW-3/24/04-SX-W-C-F
4-AW-4/29/04-SX-W-C-F
3-AW-01-5-SOX-W-C-F
3-AW-03-2-SOX-W-C-F
AW-l/29/04-SX-W-C-F
4-AW-2/19/04-SX-W-C-F
4-AW-3/24/04-SX-W-C-F
4-AW-4/29/04-SX-W-C-F
3-AW-01-5-SOX-W-C-F
3-AW-03-2-SOX-W-C-F
AW-l/29/04-SX-W-C-F
4-AW-2/19/04-SX-W-C-F
4-AW-3/24/04-SX-W-C-F
4-AW-4/29/04-SX-W-C-F
3-AW-01-5-SOX-W-C-F
3-AW-03-2-SOX-W-C-F
AW-l/29/04-SX-W-C-F
4-AW-2/19/04-SX-W-C-F
4-AW-3/24/04-SX-W-C-F
4-AW-4/29/04-SX-W-C-F
3-AW-01-5-SOX-W-C-F
3-AW-03-2-SOX-W-C-F
AW-l/29/04-SX-W-C-F
4-AW-2/19/04-SX-W-C-F
4-AW-3/24/04-SX-W-C-F
4-AW-4/29/04-SX-W-C-F
3-AW-01-5-SOX-W-C-F
Sample
Date
11/14/2003
11/25/2003
1/29/2004
2/19/2004
3/24/2004
4/29/2004
11/14/2003
11/25/2003
1/29/2004
2/19/2004
3/24/2004
4/29/2004
11/14/2003
11/25/2003
1/29/2004
2/19/2004
3/24/2004
4/29/2004
11/14/2003
11/25/2003
1/29/2004
2/19/2004
3/24/2004
4/29/2004
11/14/2003
11/25/2003
1/29/2004
2/19/2004
3/24/2004
4/29/2004
11/14/2003
1 1/25/2003
1/29/2004
2/19/2004
3/24/2004
4/29/2004
11/14/2003
1 1/25/2003
1/29/2004
2/19/2004
3/24/2004
4/29/2004
11/14/2003
Composite
or Grab?
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Analyte
Aluminum
Aluminum
Aluminum
Aluminum
Aluminum
Aluminum
Arsenic
Arsenic
Arsenic
Arsenic
Arsenic
Arsenic
Cadmium
Cadmium
Cadmium
Cadmium
Cadmium
Cadmium
Chromium
Chromium
Chromium
Chromium
Chromium
Chromium
Copper
Copper
Copper
Copper
Copper
Copper
Iron
Iron
Iron
Iron
Iron
Iron
Lead
Lead
Lead
Lead
Lead
Lead
Nickel
Filtered
Influent
Concentration
(H2/L)
38,100
39,400
35,200
35,300
36,900
39,900
1.5U
2.5 U
1.6 U
1.6 U
3.1
2.3 U
0.44UJ
1
0.88
0.34
0.4
0.57
20. 8 J
3.9
4.4
4.5
17.2
22.4
701
732
630
661
656
765
121,000
126,000
114,000
109,000
113,000
120,000
0.88UJ
0.65 U
2.9
5.4
5.3
6.7
484
Filtered
Effluent
Concentration
(U2/L)
79.8
203 UJ
160
5U
144
25.8
12.5
3.8UJ
1.6 U
3
2.4
5.1
0.17U
0.21 UJ
0.32 U
0.098 U
0.23 U
0.23 U
16.3
9.9
0.5 U
0.45 U
6.4
13.4
4.5
1.9 U
4.7
5.6
5.6
6.5
4,030
12,800
39,200
7,100
389
105
0.88U
4.2 UJ
5.1
9.8
3.4
4.8
41.7
4-Day Average Filtered
Effluent Concentration'2'
(MS/L)
112
128
83.7
5.2
2.7
3.0
<0.20
<0.21
<0.22
6.8
4.3
5.2
4.2
4.5
5.6
15,783
14,873
11,699
5.0
5.6
5.8
70
-------
Table B-l. Data Used to Evaluate Project Objectives for the Bioreactor Treatment System, Gravity Flow Operations (continued)
Sample Number*1'
3-AW-03-2-SOX-W-C-F
AW- 1/29/04-SX-W-C-F
4-AW-2/19/04-SX-W-C-F
4-AW-3/24/04-SX-W-C-F
4-AW-4/29/04-SX-W-C-F
3-AW-01-5-SOX-W-C-F
3-AW-03-2-SOX-W-C-F
AW- 1/29/04-SX-W-C-F
4-AW-2/19/04-SX-W-C-F
4-AW-3/24/04-SX-W-C-F
4-AW-4/29/04-SX-W-C-F
3-AW-01-5-SOX-W-C-F
3-AW-03-2-SOX-W-C-F
AW- 1/29/04-SX-W-C-F
4-AW-2/19/04-SX-W-C-F
4-AW-3/24/04-SX-W-C-F
4-AW-4/29/04-SX-W-C-F
Sample
Date
1 1/25/2003
1/29/2004
2/19/2004
3/24/2004
4/29/2004
11/14/2003
1 1/25/2003
1/29/2004
2/19/2004
3/24/2004
4/29/2004
11/14/2003
11/25/2003
1/29/2004
2/19/2004
3/24/2004
4/29/2004
Composite
or Grab?
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Analyte
Nickel
Nickel
Nickel
Nickel
Nickel
Selenium
Selenium
Selenium
Selenium
Selenium
Selenium
Zinc
Zinc
Zinc
Zinc
Zinc
Zinc
Filtered
Influent
Concentration
(HB/L)
493
448
467
481
547
12.8 UJ
11.6
16.3
18
9.6
14.9
701
732
677
677
702
802
Filtered
Effluent
Concentration
(M8/L)
36.7
125
42.3
53.1
94.2
13.9
10 UJ
13.3
8
8.7
13.3
29
14.2 J
13.5
16.2
10.3
11.5
4-Day Average Filtered
Effluent Concentration'2'
(M8/L)
61.4
64.3
78.7
11.2
10.0
10.8
18.2
13.6
12.9
1 - For the influent sample, X in the sample number = 1 ; for the effluent sample, X=2
2 - The data from four consecutive sampling events were used in the calculation of the average instead of four consecutive days
|xg/L - Micrograms per liter NC - Not calculated U - Non-detect
71
-------
Table B-2. Data Used to Evaluate Project Objectives for the Bioreactor Treatment System, Recirculation Operations
Sample Number'1'
AW-6/14/04-SX-W-C-F
AW-8/19/04-SX-W-C-F
AW-12/3/04-SX-W-C-F
AW-2/3/05-SX-W-C-F
AW-3/17/05-SX-W-C-F
AW-4/27/05-SX-W-C-F
AW-6/2/05-SX-W-C-F
AW-6/14/04-SX-W-C-F
AW-8/19/04-SX-W-C-F
AW-12/3/04-SX-W-C-F
AW-2/3/05-SX-W-C-F
AW-3/17/05-SX-W-C-F
AW-4/27/05-SX-W-C-F
AW-6/2/05-SX-W-C-F
AW-6/14/04-SX-W-C-F
AW-8/19/04-SX-W-C-F
AW-12/3/04-SX-W-C-F
AW-2/3/05-SX-W-C-F
AW-3/17/05-SX-W-C-F
AW-4/27/05-SX-W-C-F
AW-6/2/05-SX-W-C-F
AW-6/14/04-SX-W-C-F
AW-8/19/04-SX-W-C-F
AW-12/3/04-SX-W-C-F
AW-2/3/05-SX-W-C-F
AW-3/17/05-SX-W-C-F
AW-4/27/05-SX-W-C-F
AW-6/2/05-SX-W-C-F
AW-6/14/04-SX-W-C-F
AW-8/19/04-SX-W-C-F
AW-12/3/04-SX-W-C-F
AW-2/3/05-SX-W-C-F
AW-3/17/05-SX-W-C-F
AW-4/27/05-SX-W-C-F
AW-6/2/05-SX-W-C-F
AW-6/14/04-SX-W-C-F
AW-8/19/04-SX-W-C-F
AW-12/3/04-SX-W-C-F
AW-2/3/05-SX-W-C-F
AW-3/17/05-SX-W-C-F
AW-4/27/05-SX-W-C-F
AW-6/2/05-SX-W-C-F
AW-6/14/04-SX-W-C-F
Sample
Data
6/16/2004
8/19/2004
12/3/2004
2/3/2005
3/17/2005
4/27/2005
6/2/2005
6/16/2004
8/19/2004
12/3/2004
2/3/2005
3/17/2005
4/27/2005
6/2/2005
6/16/2004
8/19/2004
12/3/2004
2/3/2005
3/17/2005
4/27/2005
6/2/2005
6/16/2004
8/19/2004
12/3/2004
2/3/2005
3/17/2005
4/27/2005
6/2/2005
6/16/2004
8/19/2004
12/3/2004
2/3/2005
3/17/2005
4/27/2005
6/2/2005
6/16/2004
8/19/2004
12/3/2004
2/3/2005
3/17/2005
4/27/2005
6/2/2005
6/16/2004
Composite
or Grab?
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Analyte
Aluminum
Aluminum
Aluminum
Aluminum
Aluminum
Aluminum
Aluminum
Arsenic
Arsenic
Arsenic
Arsenic
Arsenic
Arsenic
Arsenic
Cadmium
Cadmium
Cadmium
Cadmium
Cadmium
Cadmium
Cadmium
Chromium
Chromium
Chromium
Chromium
Chromium
Chromium
Chromium
Copper
Copper
Copper
Copper
Copper
Copper
Copper
Iron
Iron
Iron
Iron
Iron
Iron
Iron
Lead
Filtered
Influent
Concentration
(HB/L)
38,700
40,400
39,000
38,400
34,300
39,300
50,100
10.2 UJ
2.1 U
1.9 U
1.9U
4.8
18.7 J
12.4
1.1 UJ
0.94
1.3
0.12U
0.3 U
0.12U
0.3
17.9 J
19.3
4.8
4.6
14.9
5.8J
10.6
851
766
702
697
598
769
1,180
104,000
99,500
126,000
124,000
111,000
109,000
137,000
6.7 J
Filtered
Effluent
Concentration
(HS/L)
31.2
105
33.9
39.4 UJ
54.8 J
63.1
41.8
11.2
14.7 UJ
1.9 U
2.4 J
5.3 UJ
2.9
7.2
0.28 U
0.16 UJ
0.12U
0.12U
0.3 U
0.12U
0.28 U
14.1
11.6 J
2.7
1.2UJ
6.7
0.88U
7.5
7.6
9.5 J
1.7
1.6 U
5.4 UJ
1.7U
4.6
3,160
269
9,060
2,550
635
975
2,280
3.6
4-Day Average Filtered
Effluent Concentration'2'
(M8/L)
52.4
58.3
47.8
49.8
7.6
6.1
3.1
4.5
<0.17
<0.18
<0.17
<0.21
7.4
5.6
2.9
4.1
5.1
4.6
2.6
3.3
3,760
3,129
3,305
1,610
72
-------
Table B-2. Data Used to Evaluate Project Objectives for the Bioreactor Treatment System, Recirculation Operations (continued)
Sample Number'1'
AW-8/19/04-SX-W-C-F
AW-12/3/04-SX-W-C-F
AW-2/3/05-SX-W-C-F
AW-3/17/05-SX-W-C-F
AW-4/27/05-SX-W-C-F
AW-6/2/05-SX-W-C-F
AW-6/14/04-SX-W-C-F
AW-8/19/04-SX-W-C-F
AW-12/3/04-SX-W-C-F
AW-2/3/05-SX-W-C-F
AW-3/17/05-SX-W-C-F
AW-4/27/05-SX-W-C-F
AW-6/2/05-SX-W-C-F
AW-6/14/04-SX-W-C-F
AW-8/19/04-SX-W-C-F
AW-12/3/04-SX-W-C-F
AW-2/3/05-SX-W-C-F
AW-3/17/05-SX-W-C-F
AW-4/27/05-SX-W-C-F
AW-6/2/05-SX-W-C-F
AW-6/14/04-SX-W-C-F
AW-8/19/04-SX-W-C-F
AW-12/3/04-SX-W-C-F
AW-2/3/05-SX-W-C-F
AW-3/17/05-SX-W-C-F
AW-4/27/05-SX-W-C-F
AW-6/2/05-SX-W-C-F
Sample
Data
8/19/2004
12/3/2004
2/3/2005
3/17/2005
4/27/2005
6/2/2005
6/16/2004
8/19/2004
12/3/2004
2/3/2005
3/17/2005
4/27/2005
6/2/2005
6/16/2004
8/19/2004
12/3/2004
2/3/2005
3/17/2005
4/27/2005
6/2/2005
6/16/2004
8/19/2004
12/3/2004
2/3/2005
3/17/2005
4/27/2005
6/2/2005
Composite
or Grab?
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Composite
Analyte
Lead
Lead
Lead
Lead
Lead
Lead
Nickel
Nickel
Nickel
Nickel
Nickel
Nickel
Nickel
Selenium
Selenium
Selenium
Selenium
Selenium
Selenium
Selenium
Zinc
Zinc
Zinc
Zinc
Zinc
Zinc
Zinc
Filtered
Influent
Concentration
(HB/L)
5.9
1.7
1.4
5.3
2.3 J
5.9
525
531
531
551
481
497
585
17.7
14.4
9.5
18
7
7.1UJ
7
774
755
772
780
709
761
880
Filtered
Effluent
Concentration
(M8/L)
3.1UJ
0.73
0.72 U
3.3 J
1.1
4.6
36.8
18.9 J
154
50.5 J
59.1
79.4
89.5
12.3
7.8UJ
5.6
13.3 UJ
6.3 UJ
3.6
10.5
8.4
4.5UJ
17.5
0.97 UJ
0.92 U
11.3
18.8
4-Day Average Filtered
Effluent Concentration*2'
(Hg/L)
2.0
2.0
1.5
2.4
65.1
70.6
85.8
69.6
9.8
8.3
7.2
8.4
7.8
6.0
7.7
8.0
1 - For the influent sample, X in the sample number = 1 ; for the effluent sample, X=2
2 - The data from four consecutive sampling events were used in the calculation of the average instead of four consecutive days
(xg/L - Micrograms per liter NC - Not calculated U - Non-detect
73
-------
Table B-3. Statistical Summary of the Bioreactor Treatment System, Gravity Flow Operations Data
Analyte
Minimum
Concentration
(M8/L)
Maximum
Concentration
(M8/L)
Mean
Concentration
(M8/L)
Median
Concentration
(HS/L)
Standard
Deviation
Coefficient of
Variation
(%)
Influent
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
35,200
<1.5
0.34
3.9
630
109,000
<0.65
448
9.6
677
39,900
3.1
1.0
22.4
765
126,000
6.7
547
16.3
802
37,467
2.1
0.61
12.2
691
117,167
3.64
487
13.9
715
37,500
1.95
0.51
10.9
681
117,000
4.1
483
13.9
702
2,011
0.64
0.27
8.9
51.2
6,242
2.5
33.5
3.1
47.1
5
31
45
73
7
5
70
7
22
7
Effluent
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
<5
<1.6
<0.098
<0.45
<1.9
105
<0.88
36.7
8
10.3
160
12.5
<0.32
16.3
6.5
39,200
9.8
125
13.9
29
103
4.73
<0.21
7.83
4.8
4,885
4.7
65.5
11.2
15.8
112
3.4
<0.22
8.2
5.2
3,595
4.5
47.7
11.7
13.9
78.8
3.99
0.07
6.6
1.6
4,771
2.9
35.9
2.6
6.8
77
84
35
84
33
104
62
55
23
43
4-Day Average Effluent
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
83.7
2.7
<0.20
4.3
4.2
11,699
5.0
61.4
10.0
12.9
112
5.2
<0.22
6.8
5.6
15,783
5.8
78.7
11.2
18.2
107.9
3.63
<0.21
5.77
4.77
14,118
5.47
68.1
10.7
14.9
112
3.0
<0.21
5.3
4.5
14,873
5.6
64.3
10.8
13.6
22.4
1.37
0.01
0.90
0.74
2,144
0.42
9.27
0.61
2.88
21
38
5
16
15
15
8
14
6
19
% - Percent Hg/L - Micrograms per liter NA - Not applicable
74
-------
Table B-4. Statistical Summary of the Bioreactor Treatment System, Recirculation Operations Data
Analyte
Minimum
Concentration
(M8/L)
Maximum
Concentration
(M8/L)
Mean
Concentration
(M8/L)
Median
Concentration
(Hg/L)
Standard
Deviation
Coefficient of
Variation
(%)
Influent
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
34,300
<1.9
<0.12
4.6
598
99,500
1.4
481
7
709
50,100
18.7
1.3
19.3
1,180
137,000
6.7
585
18
880
40,029
7.43
0.60
11.1
795
115,785
4.17
529
11.5
776
39,000
4.8
0.30
10.6
766
111,000
5.30
531
9.5
772
4,837
6.53
0.50
6.30
187
13,509
2.27
34.1
5.05
51.7
12
88
84
57
24
12
54
6
44
7
Effluent
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
31.2
<1.9
<0.12
<0.88
<1.6
269
<0.72
18.9
3.6
<0.92
105
11.2
<0.3
14.1
9.5
9,060
4.6
154
12.3
18.8
52.7
6.51
<0.20
6.38
4.59
2,704
2.45
69.7
8.49
8.91
41.8
5.3
<0.16
6.7
4.6
2,280
3.1
59.1
7.8
8.4
25.7
4.87
0.09
5.15
3.15
3,000
1.57
44.2
3.63
7.35
49
75
43
81
69
111
64
63
43
82
4-Day Average Effluent
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Nickel
Selenium
Zinc
47.8
3.1
<0.17
2.9
2.6
1,610
1.5
65.1
7.2
6.0
58.3
7.6
<0.21
7.4
5.1
3,760
2.4
85.8
9.8
8.0
52.1
5.30
<0.18
4.97
3.89
2,951
1.97
72.8
8.41
7.37
51.1
5.26
<0.17
4.81
3.94
3,217
2.0
70.1
8.34
7.76
4.56
1.93
0.02
1.95
1.14
933
0.40
8.99
1.05
0.94
9
36
10
39
29
32
20
12
12
13
% - Percent Hg/L - Micrograms per liter NA - Not applicable
75
-------
APPENDIX C
DETAILED COST ELEMENT SPREADSHEETS
76
-------
Table C-l. Cost Element Details for the Compost-Free Bioreactor Treatment System - Gravity Flow Operation
I
II
III
1
a
b
c
d
e
f
g
2
a
b
c
d
Description
Site Preparation
Design (20% of capital cost)
Construction Management (15% of capital cost)
Project Management (10% of capital cost)
Preconstruction Site Work (Clearing and Chipping, Topsoil
Removal, and Debris Removal)
Subtotal
Permitting and Regulatory Requirements
Superfund Site, No Permitting Costs
Subtotal
Capital and Equipment
Compost-Free Bioreactor Treatment System
Equipment Mobilization/Demobilization
Pond and Pipe Trench Earthwork
Seep collection pond excavation, bioreactor ponds and settling
ponds excavation, sloping/riprap, trench excavation and placement
of bedding for piping
Installation of Pond Liners, Stairs, Decent Structures
Placement and seaming of liners and installation of boots for
piping in the pretreatment pond, the two bioreactor ponds, and the
two settling ponds. Installation of settling pond stairs and decant
structures. Placement of geotextile in the bottom of the aeration
channel.
Installation of Distribution Piping and Valve Vaults
Placement of 6-inch system main drain and valves,
4-inch distribution piping and valves, and 4-inch perforated
influent and effluent loops in the two bioreactors; installation of
two precast flushing vaults and ten 24-inch diameter HOPE
standpipe vaults
Placement of Bioreactor Substrate
Placement of manure layer, 3- to 6-inch cobble layer, and 6- to 9-
inch round rock layer
Erosion Control andRevegetation/Reseeding
Water Turbine and Storage Batteries
4 KW turbine and 60 KW battery (48 volt)
Subtotal
Reagent Storage and Distribution
Ethanol Storage Tank and Delivery System
Two 2,300 gallon bulk tanks, a reagent pump and viton tubing, and
line containment pad
Sodium Hydroxide Storage Tank and Delivery System
One 1,000 gallon bulk tank, a stainless steel transfer pump, a daily
make up tank, a reagent pump and viton tubing, and line
containment pad
Make up Water Storage Tank and Delivery System
One 1,000 gallon bulk tank, a pump and delivery line. Assumes a
make up water source is available, otherwise, use treated effluent
Reagent Storage Area Fencing
200 feet of eight foot high fencing, double wide access gate, razor
wire top.
Subtotal
Quantity
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Unit
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
Unit cost
$109,686.20
$82,264.65
$54,843.10
$41,392.00
$73,550.00
$136,442.00
$63,756.00
$149,263.00
$47,173.00
$10,907.00
$14,700.00
$13,400.00
$15,800.00
$2,000.00
$4,000.00
Subtotal
$109,686.20
$82,264.65
$54,843.10
$41,392.00
$288,185.95
$0.00
$0.00
$73,550.00
$136,442.00
$63,756.00
$149,263.00
$47,173.00
$10,907.00
$14,700.00
$495,791.00
$13,400.00
$15,800.00
$2,000.00
$4,000.00
35,200.00
77
-------
Table C-l. Cost Element Details for the Compost-Free Bioreactor Treatment System - Gravity Flow Operation (continued)
3
a
b
4
IV
V
VI
VII
Description
Automation
Remote Monitoring/Alarm System
Sensaphone SCADA 3000 (control system, logger, alarm)
Miscellaneous Accessories for SCADA 3000
Personal Computer
Professional Series 900 MHz Data Transceivers
Miscellaneous Accessories for Transceivers
Installation Cost (assumes 50% of equipment cost)
pH Controller System
Pulse Output Controller
Electronic Diaphragm Pumps
pH Probe and Cable
Temperature Sensor and Cable
Accessories (cables, calibration solution)
Installation Cost (assumes 25% of equipment cost)
Subtotal
Communications
Motorola 9505 Satellite Phone
Subtotal
Total Fixed Costs
System Start up and Acclimation (one time event)
System Start-up Labor (2 Field Technicians for 2 weeks)
Acclimation Period Labor (1 Field Technician for 2.5 months)
Subtotal
Consumables and Rentals (Yearly)
Ethanol
Sodium Hydroxide
Personal Protective Equipment (4 days/month)
Hydrogen Sulfide Gas Meter (4 days/month)
Water Quality Meter and Supplies (4 days/month)
Storage Connex
Subtotal
Labor (Yearly)
Field Technicians (1 day per week)
Administrative Support (5% of field effort)
Project Management (10% of field effort)
Subtotal
Utilities (Yearly)
Backup Generator (3 Kilowatt; assume required for 4 months)
Backup Generator Fuel (105 gallon/month at $2.50/gallon)
SCADA Communication Service
Satellite Phone Communications Service
Portable Toilet
Subtotal
Quantity
1
1
1
1
1
1
2
2
2
2
1
1
1
160
240
2,262
5,839
12
12
12
12
416
20
40
4
4
12
12
8
Unit
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
each
each
each
each
lump sum
lump sum
lump sum
hour
hour
gallon
gallon
month
month
month
month
hour
hour
hour
month
months
month
month
month
Unit cost
$2,495.00
$500.00
$2,000.00
$1,000.00
$500.00
$3,247.50
$1,160.00
$826.00
$220.00
$200.00
$150.00
$1,240.50
$1,495.00
$56.19
$56.19
$2.50
$0.85
$28.00
$300.00
$700.00
$325.00
$56.19
$61.16
$90.00
$800.00
$262.50
$75.00
$50.00
$325.00
Subtotal
$9,742.50
$2,495.00
$500.00
$2,000.00
$1,000.00
$500.00
$3,247.50
$6,202.50
$2,320.00
$1,652.00
$440.00
$400.00
$150.00
$1,240.50
$15,945.00
$1,495.00
$1,495.00
$836,616.95
$8,990.40
$13,485.60
$22,476.00
$5,655.00
$4,963.15
$336.00
$3,600.00
$8,400.00
$3,900.00
$26,854.15
$23,375.04
$1,223.20
$3,600.00
$28,198.24
$3,200.00
$1,048.00
$900.00
$600.00
$2,600.00
$8,348.00
78
-------
Table C-l. Cost Element Details for the Compost-Free Bioreactor Treatment System - Gravity Flow Operation (continued)
VIII
IX
X
Residual Waste Handling and Disposal (Yearly)
Off-Site Hazardous Sludge Disposal (80% moisture)
Sludge Pumping and Bag Filtration
Subtotal
Analytical Services (Yearly)
Dissolved Metals (Effluent Discharge)
Total and Leachable Metals (Waste Characterization)
Subtotal
Maintenance and Modifications (as indicated)
Replace Storage Batteries (every 5 years)
Replace Water Turbine (every 20 years)
Replace Reagent Pumps (every 2 years)
Subtotal
Total 1st Year Variable Costs
Recurring Variable Costs
Periodic Costs
40
1
52
1
1
1
2
ton
lump sum
each
each
each
each
each
$263.00
$3,795.00
$80.00
$280.00
$5,200.00
$9,000.00
$1,000.00
$10,520.00
$3,795.00
$14,315.00
$4,160.00
$280.00
$4,440.00
$5,200.00
$9,000.00
$2,000.00
$16,200.00
$104,613.39
$82,155.39
$16,200.00
Description
Total 1st Year Costs
Total 1st Year Costs/1000 gallons
Total Variable Costs/1000 gallons
Cumulative 5-Year Total Variable Costs (Present Worth at 7% Rate of Return)
Cumulative 15-Year Total Variable Costs (Present Worth at 7% Rate of Return)
Cumulative 30-Year Total Variable Costs(Present Worth at 7% Rate of Return)
Total
$941,248.34
$189.54
$16.54
$343,834.00
$764,950.00
$1,045,005.00
% - Percent MHz - Megahertz
HOPE - High Density Polyethylene SCADA - Supervisory Control and Data Acquisition
KW - Kilowatt
79
-------
Table C-2. Cost Element Details for the Compost-Free Bioreactor Treatment System - Recirculation Operation
I
II
III
1
a
b
c
d
e
f
g
h
2
a
b
c
d
Description
Site Preparation
Design (20% of capital cost)
Construction Management (15% of capital cost)
Project Management (10% of capital cost)
Preconstruction Site Work (Clearing and Chipping, Topsoil
Removal, and Debris Removal)
Subtotal
Permitting and Regulatory Requirements
Superfund Site, No Permitting Costs
Subtotal
Capital and Equipment
Compost-Free Bioreactor Treatment System
Equipment Mobilization/Demobilization
Pond and Pipe Trench Earthwork
Seep collection pond excavation, bioreactor ponds and settling
ponds excavation, sloping/riprap, trench excavation and placement
of bedding for piping
Installation of Pond Liners, Stairs, Decent Structures
Placement and seaming of liners and installation of boots for
piping in the pretreatment pond, the two bioreactor ponds, and the
two settling ponds. Installation of settling pond stairs and decant
structures. Placement of geotextile in the bottom of the aeration
channel.
Installation of Distribution Piping and Valve Vaults
Placement of 6-inch system main drain and valves,
4-inch distribution piping and valves, and 4-inch perforated
influent and effluent loops in the two bioreactors; installation of
two precast flushing vaults and ten 24-inch diameter HOPE
standpipe vaults
Placement of Bioreactor Substrate
Placement of manure layer, 3- to 6-inch cobble layer, and 6- to 9-
inch round rock layer
Erosion Control andRevegetation/Reseeding
Recirculation Pump and Piping
(1) Stainless steel submersible pump; 200 feet of 3-inch HOPE
piping; 900 feet of 2-inch HDPE piping; wiring
Water Turbine and Storage Batteries
4 KW turbine and 60 KW battery (48 volt)
Subtotal
Reagent Storage and Distribution
Ethanol Storage Tank and Delivery System
Two 2,300 gallon bulk tanks, a reagent pump and viton tubing, and
line containment pad
Sodium Hydroxide Storage Tank and Delivery System
One 1,000 gallon bulk tank, a stainless steel transfer pump, a daily
make up tank, a reagent pump and viton tubing, and line
containment pad
Make up Water Storage Tank and Delivery System
One 1,000 gallon bulk tank, a pump and delivery line. Assumes a
make up water source is available, otherwise, use treated effluent
Reagent Storage Area Fencing
200 feet of eight foot high fencing, double wide access gate, razor
wire top.
Subtotal
Quantity
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Unit
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
Unit cost
$119,189.00
$89,392.00
$59,595.00
$41,392.00
$73,550.00
$136,442.00
$63,756.00
$149,263.00
$47,173.00
$10,907.00
$6,120.00
$14,700.00
$13,400.00
$15,800.00
$2,000.00
$4,000.00
Subtotal
$119,189.00
$89,392.00
$59,595.00
$41,392.00
$309,568.00
$0.00
$0.00
$73,550.00
$136,442.00
$63,756.00
$149,263.00
$47,173.00
$10,907.00
$6,120.00
$14,700.00
$501,911.00
$13,400.00
$15,800.00
$2,000.00
$4,000.00
35,200.00
80
-------
Table C-2. Cost Element Details for the Compost-Free Bioreactor Treatment System - Recirculation Operation (continued)
3
a
b
4
IV
V
VI
VII
Description
Automation
Remote Monitoring/Alarm System
Sensaphone SCADA 3000 (control system, logger, alarm)
Miscellaneous Accessories for SCADA 3000
Personal Computer
Professional Series 900 MHz Data Transceivers
Miscellaneous Accessories for Transceivers
Installation Cost (assumes 50% of equipment cost)
pH Controller System
Pulse Output Controller
Electronic Diaphragm Pumps
pH Probe and Cable
Temperature Sensor and Cable
Accessories (cables, calibration solution)
Installation Cost (assumes 25% of equipment cost)
Subtotal
Communications
Motorola 9505 Satellite Phone
Subtotal
Total Fixed Costs
System Start up and Acclimation (one time event)
System Start-up Labor (2 Field Technicians for 2 weeks)
Acclimation Period Labor (1 Field Technician for 2.5 months)
Subtotal
Consumables and Rentals (Yearly)
Ethanol
Sodium Hydroxide
Personal Protective Equipment (4 days/month)
Hydrogen Sulfide Gas Meter (4 days/month)
Water Quality Meter and Supplies (4 days/month)
Storage Connex
Subtotal
Labor (Yearly)
Field Technicians (1 day per week)
Administrative Support (5% of field effort)
Project Management (10% of field effort)
Subtotal
Utilities (Yearly)
Backup Generator (3 Kilowatt; assume required for 4 months)
Backup Generator Fuel (105 gallon/month at $2.50/gallon)
SCADA Communication Service
Satellite Phone Communications Service
Portable Toilet
Subtotal
Quantity
1
1
1
1
1
1
2
2
2
2
1
1
1
160
240
2,630
2,651
12
12
12
12
416
20
40
4
4
12
12
8
Unit
lump sum
lump sum
lump sum
lump sum
lump sum
lump sum
each
each
each
each
lump sum
lump sum
lump sum
hour
hour
gallon
gallon
month
month
month
month
hour
hour
hour
month
months
month
month
month
Unit cost
$2,495.00
$500.00
$2,000.00
$1,000.00
$500.00
$3,247.50
$1,160.00
$826.00
$220.00
$200.00
$150.00
$1,240.50
$1,495.00
$56.19
$56.19
$2.50
$0.85
$28.00
$300.00
$700.00
$325.00
$56.19
$61.16
$90.00
$800.00
$262.50
$75.00
$50.00
$325.00
Subtotal
$9,742.50
$2,495.00
$500.00
$2,000.00
$1,000.00
$500.00
$3,247.50
$6,202.50
$2,320.00
$1,652.00
$440.00
$400.00
$150.00
$1,240.50
$15,945.00
$1,495.00
$1,495.00
$864,119.00
$8,990.40
$13,485.60
$22,476.00
$6,575.00
$2,235.35
$336.00
$3,600.00
$8,400.00
$3,900.00
$25,046.35
$23,375.04
$1,223.20
$3,600.00
$28,198.24
$3,200.00
$1,048.00
$900.00
$600.00
$2,600.00
$8,348.00
81
-------
Table C-2. Cost Element Details for the Compost-Free Bioreactor Treatment System - Recirculation Operation (continued)
VIII
IX
X
Residual Waste Handling and Disposal (Yearly)
Off-Site Hazardous Sludge Disposal (80% moisture)
Sludge Pumping and Bag Filtration
Subtotal
Analytical Services (Yearly)
Dissolved Metals (Effluent Discharge)
Total and Leachable Metals (Waste Characterization)
Subtotal
Maintenance and Modifications (as indicated)
Replace Recirculation Pump (every 5 years)
Replace Storage Batteries (every 5 years)
Replace Water Turbine (every 20 years)
Replace Reagent Pumps (every 2 years)
Subtotal
Total 1st Year Variable Costs
Recurring Variable Costs
Periodic Costs
23
1
52
1
1
1
1
2
ton
lump sum
each
each
each
each
each
each
$263.00
$3,795.00
$80.00
$280.00
$5,000.00
$5,200.00
$9,000.00
$1,000.00
$6,049.00
$3,795.00
$9,844.00
$4,160.00
$280.00
$4,440.00
$5,000.00
$5,200.00
$9,000.00
$2,000.00
$21,200.00
$98,352.59
$75,876.59
$21,200.00
Description
Total 1st Year Costs
Total 1st Year Costs/1000 gallons
Total Variable Costs/1000 gallons
Cumulative 5-Year Total Variable Costs (Present Worth at 7% Rate of Return)
Cumulative 15-Year Total Variable Costs (Present Worth at 7% Rate of Return)
Cumulative 30-Year Total Variable Costs(Present Worth at 7% Rate of Return)
Total
$962,471.59
$193.81
$15.28
$321,654.00
$715,681.00
$977,880.00
% - Percent MHz - Megahertz
HOPE - High Density Polyethylene SCADA - Supervisory Control and Data Acquisition
KW - Kilowatt
82
------- |