IN-SITU BIOLOGICALLY MEDIATED REMEDIATION

Margy Gentile

September 30, 2016

© Arcadis 2016

Disclaimers and NoticesThe 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.

© Arcadis 2016

About the Presenter

c 1 510 432 6251e margaret.gentile@arcadis.com

MARGARET GENTILE, PHD, PEAssociate Vice President, Principal EngineerIn-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.

© Arcadis 2016

Learning Objectives

After attending this session, participants should be able to:Define the keys to successful in-situ bioremediationRecognize the microbial mechanisms of treatment and which are appropriate for a given COCExplain the importance of reagent distribution and residence time for effective in-situ treatment

© Arcadis 2016

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)

© Arcadis 2016

Microbially Catalyzed

Biologically Mediated Treatment

COC = Electron Donor

Biological Oxidation

Reagent = Electron Donor

COC = Electron Acceptor

Biological Reduction

Reagent = Electron Acceptors

Microbiology

© Arcadis 2016

Engineering DistributionThere are a number of ways to deliver reagent

• Biological processes require sustained treatment

− Requires constant electron donor & acceptor supply

• Dosing design is site-specific− Volume− Frequency− Hydrogeology

SpargingGroundwater Recirculation

Land Application

Reagent Distribution

© Arcadis 2016

Injection Volumes and Injection Point Spacing

2inj inj mVol h r= π ⋅ ⋅ ⋅ θ

Injection volume

Screened interval Injection

radiusMobile porosity

For fluid injections:

Reagent Distribution

© Arcadis 2016

In-Situ Biological Treatment Design

Residence time within IRZ must be sufficient for transformationFlushing zone designed to exchange pore volumes for concentration decline

Reagent

Injection Zone

Groundwater FlowSection View

In-Situ Reactive Zone (IRZ) Flushing Zone

Residence Time

Downgradient transportof soluble reagents with

slow degradation rates

In-Situ Biological Reduction

Microbiology Design Adaptive Management

© Arcadis 2016

Microbially Catalyzed

Biologically Mediated Treatment

Reagent = Electron DonorSoluble organic compoundsSemi-soluble organic compounds

COC = Electron AcceptorChlorinated organics

Redox sensitive metalsExplosives

Biological Reduction

Microbiology

© Arcadis 2016

Reductive Dechlorination Pathways

PCETetrachloroethene

TCETrichloroethene

cis-1,2-DCEcis-1,2-dichlorethene

VCVinyl chloride

EtheneEthane

Cl

HC=C

Cl

ClCl

HC=C

Cl

H

Cl

ClC=C

Cl

Cl

Cl

HC=C

H

H

H

HC=C

H

H

Microbiology

© Arcadis 2016

Reductive Dechlorination Pathways

PCETetrachloroethene

TCETrichloroethene

cis-1,2-DCEcis-1,2-dichlorethene

VCVinyl chloride

EtheneEthane

Chlorinated Ethanes1,1,1-TCA1,1,2-TCA

1,1,2,2-TeCA1,2-DCA

Chlorinated Methanes

Carbon TetrachlorideChloroform

Methylene Chloride

MethaneEtheneEthane

Also:• Microaerobic conditions

lead to complete mineralization to CO2

• Abiotic reactions lead to acetylene/etheneendpoint

Microbiology

© Arcadis 2016

Enhanced Reductive Dechlorination Redox Conditions

Hydrogen is the primary electron donor for reductive dechlorination

Oxic

Sub-oxicAnaerobic

Sulfidic

Methanogenic

O2

H2ONO3

-

N2MnO2

SO42-

Fe(OH)3

Fe2+

Mn2+

H2SCO2

CH4

H2

H2O

Aerobes

Conditions for chlorinated ethene dechlorination

Decreasing redoxpotential

Microbiology

© Arcadis 2016

Fermentation Reactions

Hydrogen produced through the fermentation of organic carbon substrate

Microbiology

Higher fatty acidsAlcohols

Etc.

H2, CO2 Acetate

Carbohydrates (sugars)

Methane

Fermentation

Methanogenesis

© Arcadis 2016

Anaerobic Bioremediation Substrates

Gaseous

Slurry/Emulsion phases

Solid

Liquid:Water soluble

Liquid: Limited water solubility

Pure Hydrogen

MethanolEthanol

Molasses

Corn Syrup

Powdered Cheese Whey

Hydrogen Release Compound Vegetable Oil

Emulsified Vegetable Oil

Fresh Cheese Whey

ChitinBark Mulch

Peat

Rapid Acting/Quickly Consumed

Slow Releasing/ Long Lasting

Half Life (Hours)

Half Life (Days)

Lactate

Half Life (Years)

Half Life (Months)

• All produce hydrogen

• Some will be consumed faster than others

Design

© Arcadis 2016

Achieving Adequate Reagent DistributionSoluble Substrate Design

2inj inj mVol h r= π ⋅ ⋅ ⋅ θ

Need additional volume for EVO to overcome straining (15-20% more volume)

EVO Substrate Design

WATERROI

EVOROI

GW

Design

Injected substrate

ROI

GW

© Arcadis 2016

Achieving Adequate Residence Time

Carbon Footprint = IRZ

Soluble Substrate Design

Injected substrate

ROI

GW

Residence Time within IRZ(100 days)

TOC

Minimum DOC(e.g. 30 mg/L at site with background at 10 mg/L)

Injection concentration determined from substrate degradation rate, minimum DOC requirement and residence time

Design

© Arcadis 2016

Achieving Adequate Residence Time

Carbon Footprint = IRZ

Soluble Substrate Design

Injected substrate

ROI

EVO Substrate Design

WATERROI

EVOROI

•Length depends on groundwater velocity & injected ROI

Design Residence Time (100 days)

Reactive Zone within EVO ROI

GW

GW

Second barrier may be requiredResidence Time within IRZ

(100 days)

TOC

Design

•May need multiple barriers to achieve necessary residence time

© Arcadis 2016

• Reduced re-injection frequency• Guided by TOC decline and

soybean oil consumption

Sustaining IRZ: Re-injection Frequency

Re-injections guided by performance monitoring data

IRZ

Soluble Substrate Design

Injected substrate

ROI

EVO Substrate Design

WATERROI

EVOROI

IRZ

GW

GW

• Re-injection is a function of reagent degradation rate and velocity

• Routine injections conducted to sustain TOC over time

Design

© Arcadis 2016

Injection Barrier Spacing

IRZ Flushing Zone

Distance?

(based on total porosity)

Distance = (Desired Timeframe x Groundwater Velocity)/NPV

• Calculate Number of Pore Flushes to reach Treatment Objective:

−=

oPV C

CRN ln

Design

• Where: – NPV = Number of pore flushes– R = retardation factor due to sorption– C = targeted treatment concentration for

respective compound (mg/L)– Co = initial aqueous concentration (mg/L)IRZ

IRZIRZ

Flushing Zone

Flushing Zone

Flushing Zone

© Arcadis 2016

Define the Monitoring NetworkAdequate positioning is needed for optimal

performance and operational monitoring

60 to 120 days downgradient- Optimal treatment information- Demonstrates carbon transport

Immediate dose response during injection

Edge of injection radius to confirm distribution

Adaptive Management

© Arcadis 2016

Develop a Primary Decision Making Data Set

Data Discipline: collect only reliable data that can be used for decision making

Baseline Analysis:

Primary operational variables+

supplemental analyses(Fe2+, NO3

-, SO42-, alk., etc)

pH

TOC

CH4

VOCs

Remedial system design

Operational monitoring: primary variables only

Adaptive Management

© Arcadis 2016

At-a-Glance (AAG) Operational Analysis

pH• 6.2 – 8 S.U. is optimal• 5 – 9 S.U. is acceptable

VOCs and end products• Tracked in molar units• Evidence of complete treatment

TOC – target > 100 mg/LCH4 – look for increase (> 1 mg/L)

Adaptive Management

© Arcadis 2016

Additional Key Operational Considerations

Parameter Key Observations Management Solution

Secondary water quality

• Metals mobilization (Fe, Mn, As)• Gas generation• Injection well biofouling

• Regulatory communication• Monitoring demonstration

Methane • Evaluate during proposal• Include contingency

• Arcadis methane management protocol

Bioaugmentation• No evidence of complete

dechlorination pathway• Limited/slow dechlorination rates

• Confirm TOC presence• Deliver consortia concurrent with

injection

Adaptive Management

© Arcadis 2016

… and now some examples

© Arcadis 2016

Downey, CA

1Q11

Baseline

1Q12

Lubbock, TX

2004 2006

2008 2012

In-Situ Biological Oxidation

© Arcadis 2016

Biological Oxidation- Microbiology

COC = Electron Donors

Reagents = Electron Acceptors (Oxidants)

Aerobic Anaerobic

COC = Electron Donors

Electron Acceptors (Oxidants)• Anaerobic- sulfate, nitrate

• Most thermodynamically favorable fast rates• IRZ limited to injection zone

• Increased kinetics with sulfate addition• Ambient- 1st order, 10s to 100s mg/L• Engineered- zero order, 1,000s mg/L

• Treatment zone can migrate beyond radius of influence

• Petroleum hydrocarbons• MTBE

• Petroleum hydrocarbons• MTBE• Lesser chlorinated organics

• Aerobic- O2, O3, H2O2, ORM

© Arcadis 2016

Biological Oxidation StoichiometryStoichiometry (Benzene Example)

Effective Concentration in Water (mg/L)

PotentialMax Benzene Degraded (mg/L)

Potential Complications

Oxygen (ambientair sources)

C6H6 + 7.5 O2 6 CO2 + 3 H2O

0.33 g benzene/g oxygen

9-10 3.0-3.3 • Limited solubility• Numerous non-target

scavengers• Potential clogging through

biofouling and iron precipitation

Oxygen(pure)

60-70 19.8-23.1

Sulfate C6H6 + 3.75 SO42- + 10.125 H2O

→ 3.75 S2-+ 6 CO2

0.22 g benzene/ g sulfate

70,000 (Na2SO4)

250,000 (MgSO4)

9,000

25,000

• Secondary MCL for sulfate –250 mg/L

• H2S: rarely documented as issue in field

(Adapted from Cunningham et al, 2001)• These are examples• Nitrate is another common oxidant

© Arcadis 2016

Targets of Aerobic Oxidants

*Note that there will be TDC remaining when the site achieves compliance

PetroleumHydrocarbons

(all forms)

Degradable(Natural)OrganicMatter

Other Degradable

Contaminants(oxygenates)

Reduced Inorganics(Fe2+, etc)

(as C)

Total Degradable Carbon

© Arcadis 2016

Oxygen Demand Development in an Anaerobic System0.20

0.15

0.10

0.05

0

pO2 = 0.20 atm

pO2 = 0.00 atm

Soil

Che

mic

al O

xyge

n D

eman

dSoi

l Oxy

gen

Parti

al P

ress

ure,

pO

2

Oxygen depletion due to chemical oxygen demand

O2 depletion during initial shutdown due to chemical oxygen demand and biological activity

Rate of metabolic O2 depletion increases after microbial populations grow to “steady-state” levels

Air Inject Air InjectOff OffAir Inject

Off

Lag-time in free O2 due to oxidation of reactive, reduced ions

Fe2+ Fe3+

Mn2+ MnO2NO2- NO3

-

SO32- SO4

2-

H2S S(s)

© Arcadis 2016

Anaerobic Biological Oxidation Design Basis

CSM Requirements

DesignConsiderations

• Estimate contaminant mass and stoichiometric electron acceptor payload to estimate cleanup timeframe

• Sulfate utilization effective half-life (10 – 20 days @15 C)• Delivery focused on sustained electron acceptor availability

(6-12 months BTEX)

• No drainable NAPL• Target mass present in saturated zone• Mutliple lines of biogeochemical evidence of intrinsic

occurrence

© Arcadis 2016

How can we apply ABOx?

INCREASED COST

SOLID SULFATE LAND APPLICATION

SULFATE BATCH WELL INJECTION

GROUNDWATER RECIRCULATION AND

SULFATE DOSING

Other:• Using nitrate…• Excavation backfill mixing• Direct push gypsum injection

© Arcadis 2016

Sulfate Land Application

1600 920800 940920800

1.3

580 420

310 410

82

1432

48

8.64.7

0.32

3.45.9

2.23.8 4

0.0023

2.7 2.41.7

4 2.92

4.26.8

271 211119

50.1

12371.7 107

182 276

83.4

61.3 43.9

15.5 17.8

6.1

115

1130464

674

0.001

0.01

0.1

1

10

100

1000

10000

0

4

8

12

16

20

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-13

Mon

thly

Rai

nfal

l (in

ches

)

Benz

ene

(ug/

L), S

ulfa

te (m

g/L)

, Met

hane

(ug/

L)

Methane

Sulfate

Benzene

Hurricane Irene

Gyp

sum

Gyp

sum

Hurricane Sandy

© Arcadis 2016

Injection Well Delivery

© Arcadis 2016

Biovent and Sulfate RecirculationBenzene (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)

© Arcadis 2016

Learning Objectives Revisited

After attending this session, participants should be able to:Define the keys to successful in-situ bioremediationRecognize the microbial mechanisms of treatment and which are appropriate for a given COCExplain the importance of reagent distribution and residence time for effective in situ treatment

© Arcadis 2016

Arcadis.Improving quality of life.