Principles and Practices of Enhanced Anaerobic Bioremediation of Chlorinated Solvents

457 Pages·2004·6.21 MB·English

FINAL
Principles and Practices of
Enhanced Anaerobic Bioremediation
of Chlorinated Solvents
August 2004
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PRINCIPLES AND PRACTICES OF ENHANCED ANAEROBIC
BIOREMEDIATION OF CHLORINATED SOLVENTS

August 2004

Prepared for:

Air Force Center for Environmental Excellence
Brooks City-Base, Texas

Naval Facilities Engineering Service Center
Port Hueneme, California

and

Environmental Security Technology Certification Program
Arlington, Virginia
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ACKNOWLEDGEMENTS

The Parsons Corporation (Parsons) prepared this Principles and Practices document under
contract to the Air Force Center for Environmental Excellence (AFCEE, Contract F41624-00-
D-8024) and the Naval Facilities Engineering Service Center (NFESC, Contract N47408-98-
D-7527). The NFESC contract was funded by the Environmental Security Technology
Certification Program (ESTCP). The United States Army Corp of Engineers (USACE)
assisted with technical review. This document is intended to assist AFCEE, NFESC, ESTCP,
USACE and their United States (US) Department of Defense (DoD) technology-transition
partners in evaluating and applying enhanced in situ anaerobic bioremediation for restoration
of groundwater contaminated with chlorinated solvents. The authors acknowledge the
assistance of numerous individuals who provided review services, and to several
environmental contractors that provided case studies and information regarding respective
areas of expertise. These individuals and their affiliations are listed in Appendix A.
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DISCLAIMER
In no event shall either the United States Government or Parsons have any responsibility
or liability for any consequences of any use, misuse, inability to use, or reliance on the
information contained herein; nor does either warrant or otherwise represent in any way the
accuracy, adequacy, efficacy, or applicability of the contents hereof. Mention of trade names
in this report is for information purposes only; no endorsement is implied.
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TABLE OF CONTENTS
Page
ACKNOWLEGEMENTS....................................................................................................i
DISCLAIMER.....................................................................................................................ii
SECTION 1 - STATE OF THE PRACTICE...................................................................1-1
1.1 Problem Statement................................................................................................1-1
1.2 Objective...............................................................................................................1-2
1.2.1 Intended Audience....................................................................................1-3
1.2.2 Using the Principles and Practices Document..........................................1-3
1.3 Roadmap to Enhanced In Situ Anaerobic Bioremediation...................................1-4
1.4 Technology Description.......................................................................................1-6
1.4.1 Remedial Objectives and Regulatory Acceptance.....................................1-7
1.4.2 Applicable Contaminants (Chlorinated Solvents)....................................1-7
1.4.3 Degradation Processes..............................................................................1-8
1.4.4 Anaerobic Reductive Dechlorination.......................................................1-9
1.4.5 Molecular Hydrogen as a Direct Electron Donor...................................1-11
1.4.6 Microbiology of Anaerobic Reductive Dechlorination..........................1-12
1.5 Application of Enhanced Anaerobic Bioremediation.........................................1-12
1.5.1 Technology Screening............................................................................1-13
1.5.2 Substrate (Electron Donor) Alternatives................................................1-14
1.5.3 System Configurations...........................................................................1-16
1.5.4 Delivery Options....................................................................................1-19
1.6 Alternative Remedial Strategies.........................................................................1-20
1.7 Advantages and Limitations of Enhanced Anaerobic Bioremediation..............1-21
1.7.1 Advantages of Enhanced Anaerobic Bioremediation.............................1-21
1.7.2 Potential Limitations of Enhanced Anaerobic Bioremediation..............1-22
1.8 Summary.............................................................................................................1-23
SECTION 2 - MICROBIOLOGICAL AND GEOCHEMICAL CONSIDERATIONS..2-1
2.1 Microbial Processes and Degradation Pathways..................................................2-2
2.1.1 Degradation Processes for Chlorinated Solvents.....................................2-2
2.1.2 Anaerobic Reductive Dechlorination.......................................................2-2
2.1.3 Native Electron Acceptors and Oxidation-Reduction Conditions...........2-5
2.1.4 Fermentation Reactions and Molecular Hydrogen...................................2-6
2.1.4.1 Fermentation............................................................................2-7
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TABLE OF CONTENTS (Continued)
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2.1.4.2 Donor-Specific Fermentation Reactions.................................2-7
2.1.4.3 Molecular Hydrogen as an Electron Donor.............................2-8
2.1.4.4 Stoichiometric Relationships.................................................2-11
2.1.5 Alternate Degradation Processes............................................................2-12
2.1.5.1 Oxidative Pathways...............................................................2-12
2.1.5.2 Abiotic Pathways...................................................................2-13
2.1.6 Relative Rates of Degradation................................................................2-14
2.2 Microbial Communities Required for Anaerobic Reductive Dechlorination....2-16
2.2.1 The Role and Occurrence of Dehalococcoides Microorganisms...........2-17
2.2.2 Microbial Ecology..................................................................................2-19
2.2.3 Occurrence and Site-Specific Variability...............................................2-19
2.2.4 Environmental Requirements.................................................................2-20
2.2.5 Reasons for Apparent/Actual DCE Stall or Slowdown........................2-21
2.2.6 Bioaugmentation.....................................................................................2-22
2.3 Effects of Substrate Addition on DNAPL and Sorbed Contaminant Mass........2-23
SECTION 3 - PRELIMINARY SCREENING................................................................3-1
3.1 Remedial Objectives and Regulatory Considerations For Enhanced
Anaerobic Bioremediation....................................................................................3-2
3.1.1 Remedial Objectives...................................................................................3-2
3.1.2 Regulatory Considerations.........................................................................3-3
3.2 Conceptual Site Models........................................................................................3-4
3.2.1 Classification System for Chlorinated Solvent Plumes............................3-6
3.2.1.1 Type 1 Environment: Groundwater Systems that are Highly
Anaerobic due to High Levels of Organic Carbon..................3-6
3.2.1.2 Type 2 Environment: Systems that are Mildly Anaerobic
due to Moderate Levels of Organic Carbon............................3-7
3.2.1.3 Type 3 Environment: Aerobic Systems with Low Levels of
Organic Carbon........................................................................3-8
3.2.1.4 Mixed Environments and Sequential Anaerobic/Aerobic
Degradation..............................................................................3-8
3.3 Site Screening Technical Considerations.............................................................3-9
3.3.1 Contaminant Distribution.......................................................................3-10
3.3.2 Microbiology..........................................................................................3-11
3.3.3 Hydrogeology.........................................................................................3-12
3.3.4 Groundwater Geochemistry....................................................................3-13
3.4 Potential Adverse Impacts..................................................................................3-15
3.4.1 Water Quality.........................................................................................3-15
3.4.1.1 Mobilization of CAHs...........................................................3-15
3.4.1.2 Secondary Water Quality Issues............................................3-16
3.4.2 Generation of Volatile Byproducts and Noxious Gases.........................3-18
3.5 Proceeding with Enhanced Anaerobic Bioremediation......................................3-18
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TABLE OF CONTENTS (Continued)
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SECTION 4 - PRE-DESIGN............................................................................................4-1
4.1 Evaluating Existing Data......................................................................................4-3
4.1.1 Reviewing Field Data for Anaerobic Biodegradation Potential...............4-4
4.1.2 Geochemical Requirements for Anaerobic Dechlorination.....................4-5
4.1.3 Justification for Proceeding at Sites Lacking Evidence of Anaerobic
Dechlorination..........................................................................................4-6
4.2 Site-Specific Evaluations for Engineered Anaerobic Bioremediation.................4-6
4.2.1 Pre-Design Screening Techniques............................................................4-7
4.2.2 Optional Analytical Methods...................................................................4-9
4.3 Laboratory Microcosms......................................................................................4-10
4.3.1 Microcosm Design..................................................................................4-10
4.3.2 Utility of Microcosm Tests.....................................................................4-11
4.3.3 Applying Microcosm Results.................................................................4-12
4.4 Small-Scale Pilot Tests and Substrate Utilization Tests....................................4-13
4.5 Molecular Screening Techniques.......................................................................4-14
4.5.1 Molecular Identification Methods..........................................................4-14
4.5.2 Using Molecular Identification Data......................................................4-17
4.5.3 Potential for False Negatives and False Positives..................................4-18
4.6 When Should Bioaugmentation be Considered?................................................4-18
SECTION 5 - SYSTEM DESIGN AND ENGINEERING..............................................5-1
5.1 Remedial Objectives and Technical Approach....................................................5-1
5.2 System Configurations.........................................................................................5-2
5.2.1 Source Area Treatment.............................................................................5-2
5.2.2 Biobarrier Containment Systems..............................................................5-3
5.2.3 Plume-wide Treatment Strategies.............................................................5-4
5.3 Substrate (Electron Donor) Options.....................................................................5-5
5.4 Substrate Delivery Options..................................................................................5-9
5.4.1 Direct Injection.......................................................................................5-10
5.4.2 Recirculation...........................................................................................5-11
5.4.3 Biowall Trenches....................................................................................5-12
5.5 Substrate Mixing and Delivery...........................................................................5-13
5.5.1 Treatment Zone Volume and Radius of Influence.................................5-13
5.5.2 Substrate (Electron Donor) Loading and Lifespan.................................5-15
5.5.3 Soluble Substrate Systems......................................................................5-19
5.5.3.1 Suitability of Soluble Substrate Systems...............................5-19
5.5.3.2 Soluble Substrate Types........................................................5-20
5.5.3.3 Mixing and Delivery of Soluble Substrates...........................5-21
5.5.4 Viscous Fluid Substrate Systems............................................................5-23
5.5.4.1 Suitability of Viscous Fluids as Long-lasting Substrates......5-23
5.5.4.2 Hydrogen Release Compound (HRC®) Applications............5-23
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TABLE OF CONTENTS (Continued)
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5.5.4.3 Vegetable (Edible) Oil Applications.....................................5-24
5.5.5 Solid Substrates (Mulch and Compost)..................................................5-27
5.5.6 Experimental Substrates.........................................................................5-29
5.5.6.1 Whey......................................................................................5-29
5.5.6.2 Chitin.....................................................................................5-29
5.5.6.3 Gaseous Hydrogen.................................................................5-30
5.6 Implementation Constraints................................................................................5-30
5.6.1 Geochemical Design Considerations for Substrate Selection................5-31
5.6.2 Hydrogeologic Considerations for Substrate Delivery..........................5-31
5.6.3 Short-Circuiting or Substrate Bypass.....................................................5-32
5.6.4 Changes in Hydraulic Conductivity.......................................................5-33
5.6.5 Biofouling Control Methods...................................................................5-34
5.7 Implementing Bioaugmentation.........................................................................5-34
5.7.1 Technical Approaches to Bioaugmentation............................................5-34
5.7.2 Culture Selection and Estimation of Volume Requirements..................5-36
5.7.3 Selection of Electron Donors for Bioaugmentation...............................5-37
5.7.4 Adding Bioaugmentation Cultures to the Subsurface............................5-38
5.7.5 Bioaugmentation Performance Monitoring............................................5-38
5.8 System Design Summary....................................................................................5-38
SECTION 6 - SYSTEM MONITORING........................................................................6-1
6.1 Monitoring Strategies...........................................................................................6-1
6.1.1 Baseline Characterization.........................................................................6-2
6.1.1.1 Soil and Soil Gas Analyses......................................................6-2
6.1.1.2 Groundwater Analyses.............................................................6-4
6.1.1.3 Hydraulic Characterization......................................................6-9
6.1.2 Process Monitoring.................................................................................6-10
6.1.3 Performance Monitoring........................................................................6-12
6.2 Monitoring System Design.................................................................................6-13
6.2.1 Monitoring Network Design...................................................................6-13
6.2.2 Monitoring Frequency............................................................................6-14
6.3 Data Interpretation..............................................................................................6-15
6.3.1 Anticipated Changes in CAHs and Biogeochemistry............................6-15
6.3.2 Changes in Contaminant Concentration and Mass.................................6-16
6.3.2.1 Calculation of Molar Concentrations....................................6-17
6.3.2.2 Contaminant Molar Concentration Plots...............................6-18
6.3.2.3 Changes in Total Molar Concentration.................................6-20
6.3.2.4 Changes in Molar Fractions...................................................6-21
6.3.3 Statistical Techniques.............................................................................6-22
6.3.4 Geochemistry..........................................................................................6-23
6.3.4.1 Competing Electron Acceptors..............................................6-23
6.3.4.2 General Geochemical Indicator Parameters..........................6-24
6.3.5 Microbial Evaluation..............................................................................6-25
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