IN-SITU BIOLOGICALLY MEDIATED REMEDIATION. Margy Gentile September 30, 2016

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1 IN-SITU BIOLOGICALLY MEDIATED REMEDIATION Margy Gentile September 30, 2016

2 Disclaimers and Notices The materials herein are intended to furnish viewers with a summary and overview of general information on matters that they may find to be of interest, and are provided solely for personal, non-commercial, and informational purposes. The materials and information contained herein are subject to continuous change and may not be current, correct, or error free, and should not be construed as professional advice or service. You should consult with an Arcadis or other professional familiar with your particular factual situation for advice concerning specific matters. THE MATERIALS AND INFORMATION HEREIN ARE PROVIDED "AS IS" AND WITH ALL FAULTS AND WITHOUT ANY REPRESENTATION OR WARRANTY, EXPRESS, IMPLIED OR STATUTORY, OF ANY KIND BY ARCADIS, INCLUDING, BUT NOT LIMITED TO, WARRANTIES OF MERCHANTABILITY, NON- INFRINGEMENT, NO ERRORS OR OMISSIONS, COMPLETENESS, ACCURACY, TIMELINESS, OR FITNESS FOR ANY PARTICULAR PURPOSE. ARCADIS DISCLAIMS ALL EQUITABLE INDEMNITIES. ANY RELIANCE ON THE MATERIALS AND INFORMATION HEREIN SHALL BE AT YOUR SOLE RISK. ARCADIS DISCLAIMS ANY DUTY TO UPDATE THE MATERIALS. ARCADIS MAY MAKE ANY OTHER CHANGES TO THE MATERIALS AT ANY TIME WITHOUT NOTICE. The materials are protected under copyright laws and may not be copied, reproduced, transmitted, displayed, performed, distributed, rented, sublicensed, altered, or otherwise used in whole or in part without Arcadis' prior written consent.

3 About the Presenter MARGARET GENTILE, PHD, PE Associate Vice President, Principal Engineer In-Situ Reactive Treatment Lead for Arcadis North America 16 years of experience in environmental engineering with a strong focus on in-situ remediation design, implementation, and optimization for organic and inorganic contaminants. She particularly enjoys providing technical expertise on microbial and geochemical aspects of treatment, remediation of metals, and tackling large, complex plumes. c e margaret.gentile@arcadis.com

4 Learning Objectives After attending this session, participants should be able to: Define the keys to successful in-situ bioremediation Recognize the microbial mechanisms of treatment and which are appropriate for a given COC Explain the importance of reagent distribution and residence time for effective in-situ treatment

5 Keys to In-Situ Biologically-Mediated Remediation Microbiology: Stimulate appropriate biogeochemical conditions Achieve adequate reagent distribution in the subsurface Provide sufficient residence time (function of reaction kinetics and groundwater flow conditions)

6 Biologically Mediated Treatment Microbiology Biological Oxidation Microbially Catalyzed Biological Reduction COC = Electron Donor Reagent = Electron Donor Reagent = Electron Acceptors COC = Electron Acceptor

7 Engineering Distribution There are a number of ways to deliver reagent Sparging Groundwater Recirculation Reagent Distribution Biological processes require sustained treatment Requires constant electron donor & acceptor supply Dosing design is site-specific Volume Frequency Hydrogeology Land Application

8 Injection Volumes and Injection Point Spacing Reagent Distribution For fluid injections: Injection volume Screened interval Injection radius Mobile porosity Vol =π h r θ 2 inj inj m

9 In-Situ Biological Treatment Design Residence Time Reagent Section View Groundwater Flow Downgradient transport of soluble reagents with slow degradation rates Injection Zone In-Situ Reactive Zone (IRZ) Flushing Zone Residence time within IRZ must be sufficient for transformation Flushing zone designed to exchange pore volumes for concentration decline

10 In-Situ Biological Reduction Microbiology Design Adaptive Management

11 Biologically Mediated Treatment Microbiology Biological Reduction Microbially Catalyzed Reagent = Electron Donor Soluble organic compounds Semi-soluble organic compounds COC = Electron Acceptor Chlorinated organics Redox sensitive metals Explosives

12 Reductive Dechlorination Pathways Microbiology PCE Tetrachloroethene Cl Cl C=C Cl Cl TCE Trichloroethene Cl H C=C Cl Cl cis-1,2-dce cis-1,2-dichlorethene Cl H C=C Cl H VC Vinyl chloride Cl H C=C H H Ethene Ethane H H C=C H H

13 Reductive Dechlorination Pathways Microbiology PCE Tetrachloroethene TCE Trichloroethene cis-1,2-dce cis-1,2-dichlorethene VC Chlorinated Ethanes 1,1,1-TCA 1,1,2-TCA 1,1,2,2-TeCA 1,2-DCA Chlorinated Methanes Carbon Tetrachloride Chloroform Methylene Chloride Also: Microaerobic conditions lead to complete mineralization to CO 2 Abiotic reactions lead to acetylene/ethene endpoint Vinyl chloride Ethene Ethane Ethene Ethane Methane

14 Enhanced Reductive Dechlorination Redox Conditions Microbiology Oxic O 2 H 2 O Aerobes NO 3 - Decreasing redox potential Sub-oxic Anaerobic N 2 MnO 2 Mn 2+ Fe(OH) 3 Sulfidic Fe 2+ SO 4 2- H 2 S Conditions for chlorinated ethene dechlorination Methanogenic CO 2 CH 4 H 2 O H 2 Hydrogen is the primary electron donor for reductive dechlorination

15 Fermentation Reactions Microbiology Carbohydrates (sugars) Higher fatty acids Alcohols Etc. Fermentation H 2, CO 2 Acetate Methane Methanogenesis Hydrogen produced through the fermentation of organic carbon substrate

16 Anaerobic Bioremediation Substrates Design Gaseous Pure Hydrogen All produce hydrogen Some will be consumed faster than others Liquid: Water soluble Methanol Ethanol Lactate Molasses Corn Syrup Powdered Cheese Whey Liquid: Limited water solubility Hydrogen Release Compound Vegetable Oil Slurry/Emulsion phases Solid Fresh Cheese Whey Emulsified Vegetable Oil Chitin Bark Mulch Peat Rapid Acting/ Quickly Consumed Slow Releasing/ Long Lasting Half Life (Hours) Half Life (Days) Half Life (Months) Half Life (Years)

17 Achieving Adequate Reagent Distribution Soluble Substrate Design EVO Substrate Design Design GW WATER ROI GW Injected substrate ROI EVO ROI Vol =π h r θ 2 inj inj m Need additional volume for EVO to overcome straining (15-20% more volume)

18 Achieving Adequate Residence Time Soluble Substrate Design Design GW Carbon Footprint = IRZ Injected substrate ROI TOC Residence Time within IRZ (100 days) Injection concentration determined from substrate degradation rate, minimum DOC requirement and residence time Minimum DOC (e.g. 30 mg/l at site with background at 10 mg/l)

19 Achieving Adequate Residence Time Soluble Substrate Design EVO Substrate Design Design Design Residence Time (100 days) GW Carbon Footprint = IRZ WATER ROI GW Reactive Zone within EVO ROI Injected substrate ROI Residence Time within IRZ (100 days) EVO ROI Second barrier may be required TOC Length depends on groundwater velocity & injected ROI May need multiple barriers to achieve necessary residence time

20 Sustaining IRZ: Re-injection Frequency Soluble Substrate Design EVO Substrate Design Design GW IRZ GW WATER ROI Injected substrate ROI Re-injection is a function of reagent degradation rate and velocity Routine injections conducted to sustain TOC over time EVO ROI IRZ Reduced re-injection frequency Guided by TOC decline and soybean oil consumption Re-injections guided by performance monitoring data

21 Injection Barrier Spacing Design IRZ IRZ Flushing Zone IRZ Flushing Zone Distance? Flushing Zone IRZ Flushing Zone Calculate Number of Pore Flushes to reach Treatment Objective: N PV = R ln C C Where: N PV = Number of pore flushes R = retardation factor due to sorption C = targeted treatment concentration for respective compound (mg/l) C o = initial aqueous concentration (mg/l) Distance = (Desired Timeframe x Groundwater Velocity)/N PV o (based on total porosity)

22 Define the Monitoring Network Adequate positioning is needed for optimal performance and operational monitoring Adaptive Management 60 to 120 days downgradient - Optimal treatment information - Demonstrates carbon transport Edge of injection radius to confirm distribution Immediate dose response during injection

23 Develop a Primary Decision Making Data Set Baseline Analysis: ph Adaptive Management Primary operational variables + supplemental analyses (Fe 2+, NO 3-, SO 4 2-, alk., etc) TOC Remedial system design CH 4 Operational monitoring: primary variables only VOCs Data Discipline: collect only reliable data that can be used for decision making

24 At-a-Glance (AAG) Operational Analysis Adaptive Management TOC target > 100 mg/l CH 4 look for increase (> 1 mg/l) ph S.U. is optimal 5 9 S.U. is acceptable VOCs and end products Tracked in molar units Evidence of complete treatment

25 Additional Key Operational Considerations Adaptive Management Parameter Key Observations Management Solution Secondary water quality Methane Metals mobilization (Fe, Mn, As) Gas generation Injection well biofouling Evaluate during proposal Include contingency Regulatory communication Monitoring demonstration Arcadis methane management protocol Bioaugmentation No evidence of complete dechlorination pathway Limited/slow dechlorination rates Confirm TOC presence Deliver consortia concurrent with injection

26 and now some examples

27 Downey, CA Baseline 1Q11 1Q12

28 Lubbock, TX

29 In-Situ Biological Oxidation

30 Biological Oxidation- Microbiology Aerobic COC = Electron Donors Petroleum hydrocarbons MTBE Lesser chlorinated organics Reagents = Electron Acceptors (Oxidants) Aerobic- O 2, O 3, H 2 O 2, ORM Most thermodynamically favorable fast rates IRZ limited to injection zone Anaerobic COC = Electron Donors Petroleum hydrocarbons MTBE Electron Acceptors (Oxidants) Anaerobic- sulfate, nitrate Increased kinetics with sulfate addition Ambient- 1 st order, 10s to 100s mg/l Engineered- zero order, 1,000s mg/l Treatment zone can migrate beyond radius of influence

31 Biological Oxidation Stoichiometry Oxygen (ambient air sources) Oxygen (pure) Sulfate Stoichiometry (Benzene Example) C 6 H O 2 6 CO H 2 O 0.33 g benzene/g oxygen C 6 H SO H 2 O 3.75 S CO g benzene/ g sulfate Effective Concentration in Water (mg/l) Potential Max Benzene Degraded (mg/l) Potential Complications Limited solubility Numerous non-target scavengers Potential clogging through biofouling and iron precipitation 70,000 (Na 2 SO 4 ) 250,000 (MgSO 4 ) 9,000 25,000 Secondary MCL for sulfate 250 mg/l H 2 S: rarely documented as issue in field (Adapted from Cunningham et al, 2001) These are examples Nitrate is another common oxidant

32 Targets of Aerobic Oxidants Petroleum Hydrocarbons (all forms) Degradable (Natural) Organic Matter Other Degradable Contaminants (oxygenates) Reduced Inorganics (Fe 2+, etc) (as C) Total Degradable Carbon *Note that there will be TDC remaining when the site achieves compliance

33 Oxygen Demand Development in an Anaerobic System 0.20 po 2 = 0.20 atm Soil Chemical Oxygen DemandSoil Oxygen Partial Pressure, po Oxygen depletion due to chemical oxygen demand Fe 2+ Fe 3+ Mn 2+ MnO 2 NO 2- NO - 3 SO 2-3 SO 2-4 H 2 S S (s) Air Inject Off O 2 depletion during initial shutdown due to chemical oxygen demand and biological activity Air Inject po 2 = 0.00 atm Lag-time in free O 2 due to oxidation of reactive, reduced ions Off Rate of metabolic O 2 depletion increases after microbial populations grow to steadystate levels Air Inject Off

34 Anaerobic Biological Oxidation Design Basis CSM Requirements Design Considerations No drainable NAPL Target mass present in saturated zone Mutliple lines of biogeochemical evidence of intrinsic occurrence Estimate contaminant mass and stoichiometric electron acceptor payload to estimate cleanup timeframe Sulfate utilization effective half-life (10 20 C) Delivery focused on sustained electron acceptor availability (6-12 months BTEX)

35 How can we apply ABOx? SOLID SULFATE LAND APPLICATION SULFATE BATCH WELL INJECTION GROUNDWATER RECIRCULATION AND SULFATE DOSING INCREASED COST Other: Using nitrate Excavation backfill mixing Direct push gypsum injection

36 Sulfate Land Application Hurricane Irene 20 Hurricane Sandy Monthly Rainfall (inches) Gypsum Benzene Sulfate Methane Gypsum Benzene (ug/l), Sulfate (mg/l), Methane (ug/l) May-10 Aug-10 Nov-10 Feb-11 May-11 Aug-11 Nov-11 Feb-12 May-12 Aug-12 Nov-12 Feb-13 May

37 Injection Well Delivery

38 Biovent and Sulfate Recirculation Benzene (5 ug/l) Benzene (50 ug/l) Benzene (500 ug/l) Benzene (1,000 ug/l) Benzene (5,000 ug/l) Hybrid design remedy Biovent operation to reduce smear zone mass Sulfate recirculation for 3 years (15MM gallons treated)

39 Learning Objectives Revisited After attending this session, participants should be able to: Define the keys to successful in-situ bioremediation Recognize the microbial mechanisms of treatment and which are appropriate for a given COC Explain the importance of reagent distribution and residence time for effective in situ treatment

40 Arcadis. Improving quality of life.