combined remedies for in situ treatment of …...combined remedies for in situ treatment of...

Combined Remedies for In Situ Treatment of Contaminants in Soil & Groundwater

Fayaz Lakhwala, Ph.D.

1. PeroxyChem Environmental Solutions 2.

Design and Application of In Situ Treatment Technologies

CT/MA

May 2016

2

Presentation Outline

Combined Remedies Initiative (CRI) – USEPA and National Groundwater Association (NGWA)

Why CRI?

Principles for CRI

Guidelines

Combined Remedies - Spatial/Temporal

Combined Remedies – In Situ

Reagents for Combined Remedies

Case Studies

Discussions

3

Combined Remedies Initiative (CRI) –

USEPA and NGWA

•In 2014, USEPA and National Groundwater Association formed a panel of regulators, academicians, consultants and technology vendors to study the application of combined remedies for soil and groundwater treatment

• 2015 Workshops in Boston, Kansas City and Denver

•Combined Remedies Sessions at RemTech and Battelle Bioremediation in 2015

•Workshops in Los Angeles and Seattle planned in 2016

•Special Issue of Groundwater & Monitoring Journal on Combined Remedies in 2016

4

Why CRI?

The goal of the CRI is to advance the practice of combined remediation

The last 10-15 years have seen several significant developments:

A larger remediation tool box

Increased awareness that contamination occurs in different phases - e.g., NAPL, sorbed, dissolved

In different sub-surface compartments – e.g., vadose, transmissive and storage zones

Under different geochemical conditions at the site

All remediation technologies have strengths and weaknesses, which differ from one technology to another

Employing technologies in suitable combination can enable strengths to be combined and weaknesses overcome

This in turn can increase efficiency, improve performance, and thereby save time, money and resources

5

Principles for Practicing

Combined Remedies

While the use of combinations of technologies has become more prevalent, there seem to be opportunities to improve the state of practice

Realization that for many, perhaps most sites, a combination of technologies is likely to be the most suitable remediation approach

Proactive vs Reactive

Clear identification of remedial objectives and metrics that provide guidelines, including technology transition points, is essential

The selection of each technology should consider how each stage of remedial effort will affect contaminant and subsurface conditions

Inclusion of contingencies in decision-documents will allow course corrections as new information is generated

Combined remedies can be applied spatially, temporally, or both

In the case of in situ treatment reagents can be combined / reagents engineered to provide multiple treatment pathways

6

Goal: Develop guidelines to practice application of Combined Remedies

“Ground rules” for selection

Technical basis for integration

Integration benefits

Challenges of managing integration

Contractual certainty vs. the evolving Conceptual Site Model

Technology transition points — the science, the engineering, and the

contract

7

Combined Remedies for In Situ

Treatment

• In Situ remediation technologies can be broadly grouped into three categories – physical (extraction/thermal), chemical (ISCO/ISCR) and biological (ISB/MNA)

• Generally speaking, these groups commonly exhibit their greatest efficiency at high, medium and low contaminant concentrations, respectively

• Their combined usage may therefore similarly follow the physical, chemical, biological sequence as remediation progresses and concentrations are reduced

Practitioners Principles

8

What, When, Where and How?

9

Combined Remedies - Spatial

Source Area - Unsaturated Zone

•Excavation, ISCO w/soil mixing, Soil Vapor Extraction (SVE) , Bioventing

Source Area - Saturated Zone

•Excavation, soil mixing, Air sparging - Soil Vapor Extraction (AS/SVE), Multi-phase Extraction (MPE), Dual-Phase Extraction (DPE), Thermal, ISCO, ISCR, In Situ Bioremediation (ISB), In Situ Solidification/Stabilization (ISS)

Plume Area (Residual Source Zone/ Dissolved Phase Plume

•Pump and Treat (P&T), AS/SVE, DPE, ISCO, ISCR, ISB, Phytoremediation, Monitored Natural Attenuation (MNA)

Off-Site Migrating Plume

•P&T, Permeable Reactive Barriers (PRBs), MNA

10


11


Transport in saprolite and bedrock

Max TCE concentration 1,200 mg/L

Very little biodegradation

14.8 acres

12


ZVI Injection

KMnO4 Injection

110 ft

ZVI Injection

KMnO4 Injection

13


14


15


16


Primary Injection ( Aug 2013)

7 New borings

29 Injection intervals

21 Saprolite

5 Transition

3 Bedrock

38.3 Tons KMnO4/sand blend

Supplemental Injection (July 2014)

10 Injection wells

5 New

5 Existing


33 Saprolite

4 Transition

11 Bedrock

31 Tons KMnO4/sand blend

Scale = 40 ft

17


15 Monitoring wells:

• 8 are ND

• 4 are >99.9% reduction from July 2014

• 3 are 88.6-99.9% reduction from July 2014

18


19


3 PRBs (508’, 441’, 219’)

62 Borings

652 Tons ZVI


157 Saprolite

106 Transition zone

105 Bedrock

20


21


22


23

Combined Remedies – Temporal

ISCO can be used as a mass reduction technology followed by:

In situ bioremediation

In situ biogeochemical remediation

In situ chemical reduction

Monitored natural attenuation

ISCO can be used following:

Thermal treatment

Surfactant/solvent enhanced extraction

Extraction systems (dual phase extraction)

ISCR can be used as a mass reduction technology followed by:

In situ bioremediation

In situ biogeochemical remediation

Monitored natural attenuation

24

In Situ Combined Remedies:

Transition Points

Asymptotic trend in contaminant concentration

Reach order of magnitude (OOMs) reduction in contaminant mass or contaminant concentration

Shift in geochemical conditions to support the next step in the treatment train

Treatment of partial suite of contaminants is achieved…… the rest has to be treated by an alternative method

25

In Situ Combined Remedies: Products that

Promote Multiple Treatment Pathways

Klozur-CR ®

Oxidation, aerobic degradation and anaerobic degradation

Applicable for mixed CVOCs and TPH contamination

EHC ®, DARAMEND ®, EHC® Liquid, Ferox Plus ™, EZVI

Chemical reduction and anaerobic biodegradation of CVOCs

EHC® Metals, MetaFix ®

Chemical reduction and anaerobic biodegradation of CVOCs and Metals

BOS 100 ® , BOS 200 ®, PlumeStop ®

Aerobic and anaerobic bioremediation with adsorption

Chemical reduction with adsorption

26

gw flow

Injection Zone: •Chemical oxidation (2-3 months): source mass removal • Extended elevated dissolved O2 for up to a year supports aerobic bioremediation source polishing

Down gradient effects:

• dissolved O2 aerobic bio

• sulfate + dissolved organic fragments anaerobic oxidation

59-01-EIT-DL

Conceptual Timeline

Persulfate chemical oxidation

Oxygen release aerobic bioremediation

Residual sulfate anaerobic oxidation

Klozur® CR

Coupling ISCO with Bioremediation

Klozur CR Composition:

• 50% Klozur persulfate

• 50% PermeOx Plus

Mechanisms Contaminant plume

27

Sulfate Enhanced Biodegradation

28

Effect of Klozur-CR on Contaminant Oxidation, Sulfide

Production and Cinnabar (HgS) Precipitation.

Klozur-CR study conducted by Western Michigan University

Three different doses of Klozur®CR (persulfate activated with calcium

peroxide) were added to slurry reactors containing sediment from the

Kalamazoo River Superfund site contaminated with PAHs, PCBs, and

mercury (in methylated and inorganic form)

The three test reactors and a control reactor were maintained for a

period of 20 weeks

The purpose of these studies was to investigate the affect of Klozur-CR

on indigenous sulfate-reducing bacteria (SRB) and chemical oxidation

of PAHs, PCBs, and methylmercury (MeHg),

And on the ability of SRB to produce sulfide and precipitate cinnabar

(HgS) after persulfate oxidation

29



30



31



32



33



Conclusions Klozur-CR was effective at chemical oxidation of the contaminants in the sediments tested, removing 91% of PCBs and 88% of PAHs at the highest dose tested (20 g/kg sediment). All doses removed over 99% of the MeHg in the sediments, and after 20 weeks

The results from the measurements of most probable number (MPN) and the relative abundance (RA) of oligonucleotide probes of SRB in the sediments clearly show that SRB were not completely killed or inhibited by addition of Klozur®CR

In fact, after an initial decrease in MPN, the lowest dose of Klozur®CR resulted in a higher MPN of SRB relative to the control Within weeks after the exhaustion of the persulfate, sulfide was produced by the activity of the SRB. This resulted in precipitation of significant amounts of cinnabar (HgS)

34

Case Study – Combined ISCO/ISCR

Optimization of In Situ Chemical Oxidation and Enhanced In Situ Bioremediation to Treat a Dilute Chlorinated Solvent Plume Stephen Rosansky and Ramona Darlington (Battelle, Columbus, Ohio, USA) Heather Rectanus and Deepti Nair (Battelle, San Diego, California, USA) Brant Smith (XDD, Stratham, New Hampshire, USA) Lora Battaglia (Navy BRAC PMO, San Diego, California, USA)

A-71, in: H.V. Rectanus and R. Sirabian (Chairs), Bioremediation and Sustainable Environmental Technologies—2011. International Symposium on Bioremediation and Sustainable Environmental Technologies (Reno, NV; June 27–30, 2011). ISBN 978-0-9819730-4-3, Battelle Memorial Institute, Columbus, OH. www.battelle.org/biosymp

45

Biogeochemical Formation of Reactive Iron Sulfide Minerals at Hickam AFB, Pearl Harbor HI

• Unconsolidated calcium carbonate aquifer • Ambient aerobic groundwater • Very high sulfate concentrations (up to 3,000 mg/L) • Very high concentrations of chlorinated ethenes (PCE,TCE, DCE,VC) (up to 550 mg/L TCE) • Efficient dechlorinating microbial culture present • EVO pilot test established reducing conditions but

result was incomplete dechlorination, accumulation of DCE and VC, and very little ethene generation.

Daniel Leigh for AFCEE, 2011

• Change to ISCR treatment with organic substrate (lactate) and ferrous iron

• Examination of mineral precipitates one year after application of treatment

• Electron microprobe analyses of the precipitates (elemental characterization of newly-formed minerals after 1 year)

46 Daniel Leigh P.G. CH.G. for AFCEE, 2011

FeS present as fine (ca. 3 - 5 µm) coating Is this important?

Estimate: each 1.0 L of groundwater with sulfate at 3,000 mg/L reduced to 3.0 µm thick FeS precipitates will yield about 1.2 ft2 of very reactive surface – YES, it is important!

47 Hayes et al., 2009. SERDP ER-

1375

How long will reactive minerals last? Influence of pH on Fe+2 release from FeS

Upflow columns packed with FeS coated sand. Effluent Fe+2 between 1 µg/L and 5 µg/L indicates that thin layers of FeS will last for 16 years under the pH 5.5 condition and 15 cm/day GW velocity. About 2% Fe released over 60 PV.

48

Contaminated Site Management: Sustainable

Remediation and Management of Soil, Sediment and Water 2014

Evaluation of In Situ Chemical Reduction to Treat Chlorinated Ethenes in High

Sulfate Aquifers

Daniel Leigh, Daniel E. Johnson and Keith L. Etchells

49

High Sulfate Aquifer

• Large built structures prevent access to plume ( 500’ wide mall, street, garage) and make remediation infrastructure expensive

• Low seepage velocity challenging for passive treatment and active both. PRB longevity considerations in design

• Elevated PCE >2000 μg/L • Aerobic Aquifer (DO ~5.0 mg/L) • Sulfate up to 3,000 mg/L • Previous bio only pilot tests unsuccessful • Incomplete degradation of PCE • Potential sulfide inhibition • Skeptical regulators: enhanced reductive dechlorination not

viewed feasible or applicable based on different technology

Site Conditions/Constraints

50

Objective

Determine if In Situ Chemical Reduction (ISCR) is capable of Treating PCE in aerobic, high sulfate aquifer

Determine if of soluble ferrous iron in EHC®-Liquid can enhances precipitation of iron sulfide.

Does removal of sulfate/sulfide result in dechlorination of PCE?

Approach: Conduct bench test to evaluate two ISCR products EHC®

EHC®Liquid + Soluble Fe2+

51

EHC-Liquid: Reaction Chemistry

The soluble carbon provides molecular hydrogen (H2) for biologically mediated enhanced reductive dechlorination (ERD)

Fe+2 Fe+3

Bacterial extraction of electrons from carbon restores Ferric (Fe+3) to Ferrous (Fe+2)

e-

ISCR reactions of Fe+2

with contaminants and formation of Fe+3

PCE Ethene

Ferrous iron may also control dissolved phase heavy metals by promoting formation of insoluble forms (e.g., arsenopyrite from arsenic).

Like EHC, EHC-L supports degradation of organic constituents by enhancing:

anaerobic bioremediation processes

abiotic reduction reactions

Iron reducing microbes will continuously regenerate ferrous minerals and a cycle is established.

As bacteria feed on the soluble carbon, they consume dissolved oxygen and other electron acceptors, thereby reducing the redox potential in groundwater.

The soluble ferrous iron (Fe2+) combines with sulfide (S-) to generate reactive iron sulfide (FeS) species in situ

52

Microcosm Setup

Sulfate – 1,800 mg/L Spiked to 2,300 mg/L

PCE – 170 μg/L Spiked to 1,800 μg/L

SDC-9TM Dhc ~ 1X108 cells/L

EHC-Liquid 10 g/L + additional 14 g/L soluble iron

Sediment and groundwater samples collected from source area wells

Bench Test Conducted at PeroxyChem’s laboratory Mississauga, ON

EHC – 10 g/L

53

Precipitation of Sulfide

Day 6

EHC-L EHC Control

Day 34

EHC-L EHC Control EHC EHC-L

Day 60

EHC EHC-L Control

Day 124

EHC-L EHC Control

54

Day 182

EHC EHC-L Control

Precipitation of Sulfide

55

Analytical Results

0

500

1,000

1,500

2,000

2,500

3,000

0 50 100 150 200

Co

nce

ntr

aati

on

)m

g/L

)

Days

Sulfate

Control

EHC

EHC-L +Fe2+

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

0 50 100 150 200

pH

(U

nit

s)

Days

pH

Control

EHC

EHC-L +Fe2+

-600

-400

-200

0

200

400

600

0 50 100 150 200

Mill

iVo

lts

Days

ORP

Control

EHC

EHC-L +Fe2+

0

1

2

3

4

5

6

7

8

0 50 100 150 200

Co

nce

ntr

atio

n (

mg

/L)

Days

Nitrate

Control

EHC

EHC-L +Fe2+

56

VOC Analytical Results

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

0 50 100 150 200

Co

nce

ntr

atio

n e

thn

e, e

than

e,

acet

yle

ne

(μ

g/L

)

Co

nce

ntr

atio

n P

CE,

TC

E, D

CE

VC

(μ

g/L

)

Days

EHC Liquid + Fe2+ - Mass Concentration

0

2

4

6

8

10

12

0 50 100 150 200

Co

nce

ntr

atio

n P

CE,

TC

E, D

CE

VC

(μ

Mo

l/L)

Days

EHC Liquid + Fe2+ - Molar Concentration

0

5

10

15

20

25

30

35

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

0 100 200C

on

cen

trat

ion

eth

ne

, eth

ane

, ac

etyl

en

e (

μg

/L)

Co

nce

ntr

atio

n P

CE,

TC

E, D

CE

VC

(μ

g/L

)

Days

EHC - Mass Concentration

0

2

4

6

8

10

12

0 50 100 150 200

Co

nce

ntr

atio

n P

CE,

TC

E, D

CE

VC

(μ

Mo

l/L)

Days

EHC - Molar Concentration

57

FeS Precipitation and Summary

FeS does not fill pore space

0.56 cm3 Mackinawite (FeS, 4.9 g/cm3) ~0.05% of volume of pore space

0.38 cm3 Pyrite (FeS2, 4.8 to 5.0 g/cm3) ~ 0.04% of volume of pore space

Reduction of 1 Liter of 3,000 mg/L of sulfate and precipitation as ferrous sulfide produces:

Significant reductions in hydraulic conductivity would not be expected from FeS precipitation

Addition of EHC and EHC-Liquid will reduce sulfate to sulfide

Sulfide precipitates as ferrous sulfide

Removal of sulfate and sulfide allows for complete reductive dechlorination of PCE

FeS promotes biogeochemical degradation of chlorinated ethenes

ISCR is a highly effective process for treating chlorinated ethenes in high sulfate aquifers

58

First Order Rate Constants for

Reactive Iron and Sulfur Minerals

Degradation of carbon tetrachloride on reactive iron and sulfur minerals in laboratory experiments. The

pseudo first order rate constant is normalized to the concentration of the mineral (units of L g-1 day-1) or

to the surface area of the mineral presented to water (L m-2 day-1).

59

In Situ Biogeochemical Transformation

(ISBGT)

Source: James Studer, InfraSur, LLC. The Biogeochemical Reductive Dehalogenation (BiRD) Groundwater Treatment Process: Presented at the FRC, Orlando, FL Oct 2015

60


(ISBGT)


61


(ISBGT)


62


(ISBGT)


Range for Effective Chlorinated Ethene

Degradation (chlororespiration)

↓

Methanogenesis CO2 + 8H+ + 8e- CH4 + 2H2O (Eh0 = -240)

Sulfate SO4 2- + 9H+ + 8e- HS- + 4H2O (Eh0 = -220)

Iron FeOOH(s) +HCO3 - + 2H+ e- FeCO3 + 2H2O (Eh0 = -50)

Oxygen O2 + 4H+ + 4e- 2H2O (Eh0 = +820)

Nitrate 2NO3- + 12H+ +10e- N2(g) + 6H2O (Eh0 = +740)

De

cre

asin

g A

mo

un

t o

f En

erg

y R

ele

ase

d D

uri

ng

Elec

tro

n T

ran

sfe

r

Manganese (IV) MnO2(s) + HCO3 +3H + + 2e - MnCO3 (s) + 2H20 (Eh0 = +520)

Redox Potential (Eh0) in Millivolts @ pH = 7

and T = 250C

500

Aerobic

Anaerobic

1000

0

-250

Arsenic (V) H3AsO4 + 2H+ +2e- H3AsO3 + H2O (Eh0 = +559)

Chromium (VI ) Cr2O72- + 14H+ + 6e- 2Cr3++7H2O (Eh0 = +1330)

Anaerobic

ClO4− + 4H2O + 8e− → Cl− + 8OH− (Eh0560) Perchlorate

Eh range for cholorinated ethene degradation

0

PCE TCE

TCE DCE

DCE VC

VC Ethene

64

H2 demand for select electron acceptors

Electron Acceptor Electron equivalents per mole

Oxygen 4

Nitrate 4

Sulfate 8

Carbon dioxide 8

Manganese (IV) 2

Ferric iron (III) 1

PCE - tetrachloroethene 8

TCE – trichloroethene 6

DCE – dichloroethene 4

VC – vinyl chloride 2

Most CE mass may be attached to aquifer matrix

65

MetaFix® Reagents

MetaFix® is a new family of reagents designed to treat heavy

metals in soil and groundwater using chemical reduction,

precipitation, and adsorption.

Reagents do not rely on biological sulfate reduction or carbon metabolism so

their performance is not inhibited by high toxicity (e.g., alkalinity, acidity, salts,

high COI concentrations)

Composed of ZVI, iron sulfides, iron oxides, alkaline earth carbonates, and

activated carbon

Treatment results in conversion of aqueous heavy metals to low solubility

mineral precipitates with broad pH stability

Can also treat cVOCS via abiotic pathways

Unique made-to-order formulations for all commonly found metallic

contaminants and site conditions

66

Composition of MetaFix® Reagents

ZVI: reductant, source of Fe+2

Iron Sulfides: source of sulfide and Fe+2, catalyst, provide both

cationic and anionic adsorption surfaces, can make aqueous iron

more reactive

Iron Oxides: provide both cationic and anionic surfaces, adatoms of

ferrous iron are very reactive

CaCO3: pH balance and source of carbonate

Activated Carbon: strong adsorbent for organically-bound metals

including arsenic, mercury, and nickel

Supplementary reagents: ion exchange, pH modification when

needed, inclusion based on results of bench-scale optimization work

67

Fe0.75Cr0.25(OH)3

EPA 625/8-80-003, 1980; Banerjee et al., 2013. Veolia Water Inc. Environ. Sci. Technol. 1988, 22, 972-977

Aqueous Solubilities of Heavy Metal

Hydroxides, Iron Hydroxides, and Sulfides

68

Independent Evaluation of MetaFix Phase II Chromium Results: MetaFix

10

100

1,000

10,000

100,000

Influent Mid-Column

Effluent

Co

nce

ntr

atio

n [

µg

/L]

Bench-scale Column Study Results Summary MetaFix(TM) Column Cr+6 Concentration [µg/L]

Day1 Day3 Day6 Day9 Day12 Day16 Day19 Day20 Day21 Day22

Day23 Day24 Day 25 Day28 Day32 Day40 Day50 Day60 Day70

69

Independent Evaluation of MetaFix

Phase II Nickel Results: MetaFix

10

100

1,000

10,000

Influent

Mid-Column

Effluent

Co

nce

ntr

atio

n [

µg

/L]

Bench-scale Column Study Results Summary MetaFix(TM) Column Ni Concentration [µg/L]

Day1 Day3 Day6 Day9 Day12 Day16 Day19 Day20 Day21 Day22

Day23 Day24 Day25 Day28 Day32 Day40 Day50 Day60 Day70

70 Confidential Client, Independent Laboratory

Treatment of Mixed Metal/cVOC Plumes

Table 1. Influence of control and treatment on heavy metal concentrations.

Biotic Control

MetaFix® I-6

71 Confidential Client, Independent Laboratory

Mixed Metal/cVOC Plumes

Table 1. Influence of control and treatment on VOC concentrations in microcosms.

Biotic Control

MetaFix® I-6

72

Where do we go from here on CRI ?

•Identification of Best Management Practices (BMPs) – e.g., insights into opportunities for coupling technologies and indicia regarding transition points

•Identification of barriers - informational, institutional, etc. - to the use of combinations of technologies

•Identification and support of research for improved understanding of technology suitability and exploitation of synergies

•Publication of useful case study and research paper information and dissemination via appropriate multi-media mechanisms

Areas of possible contributions to the state of practice include:

Fayaz Lakhwala, Ph.D.

Technology Applications Manager|Environmental Solutions

PeroxyChem, LLC

One Commerce Square

2005 Market Street, Suite 3200

Philadelphia, PA 19103

P: 908.230.9567| E:[email protected]

www.peroxychem.com/remediation

Questions ?

http://www.peroxychem.com/remediation

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