Enhanced Natural Attenuation (ENA) - Low Cost … · Enhanced Natural Attenuation (ENA) ... (e.g. non-chlorinated contaminants or molasses) ... HCl HCl H +, e 2 2-Vinyl chhloride

Workshop Monitored Natural Attenuation (MNA)Using the Self Cleaning Capacity of Nature

Kraków, October 27/28, 2009, Qubus Hotel

Dr. Thomas Held

Enhanced Natural Attenuation (ENA)- Low Cost Remediation Technologies

Initial Situation

� Degradation is not fast enough

� Too high contaminant mass

� Inhibitory Effects

� Free product phase

Initial Situation

Principles of Biodegradation

In-situ Reaktive Zone (IRZ) and Substrates

Injection Technology

Case Study

Biodegradation (Redox Reaction)

Mineralization

Corg + Eox + H2O → CO2 + Ered + H2O + Biomas

Corg = electron donor (e.g. non-chlorinated contaminants or molasses)

Eox = electron acceptor

Ered = „used“ (reduced) Electron acceptor

TPH, Aromatics, PAH,… CVOC, Halogenated Aromatics

Terminal Electron Acceptors Process

TEAox TEAred

O2 → H2O Aerobic Respiration

NO3- → N2 Denitrifikation

Mn(IV) → Mn(II) Manganese Reduction

Fe(III) → Fe(II) Iron Reduction

SO42-

→ S2-

Sulfate Reduction

CO2 → CH4 Methanogenesis

Requirement of Electron Acceptors

Reductive CVOC Degradation

C CH

Cl Cl

H

C CH

Cl H

Cl

(trans-1,2-DCE)

trans-1,2-Dichhloroethene

cis-1,2-Dichhloroethene

(cis-1,2-DCE)

+

C CH

Cl

H

H

H+, e

-22

HCl

HClH

+, e

-22

Vinyl chhloride

(VC)

C CH

H

H

H

Ethene

+

(1,1-DCE)

1,1-Dichhloroethene

C CCl

Cl H

H

C CCl

Cl

Cl

Cl

C CH

Cl Cl

ClH+, e

-22

HCl

H+, e

-22

HCl

Tetrachloroethene

(PCE) (TCE)

Trichloroethene

Initial Situation

Principles of Biodegradation

In-situ Reaktive Zone (IRZ) and Substrates

Injection Technology

Case Study

In-Situ Reactive Zone (IRZ)

“... Establishment of a zone within the aquifer,

where the biogeochemical environment is

changed in a way that natural processes are

enhanced, leading to degradation or

immobilization of the contaminants“

Technical Forms of Oxygen

� Air or technical Oxygen

O2

� Hydrogen Peroxide

H2O2 →→→→ ½ O2 + H2O

� Calcium Peroxide (or Magnesium Peroxide)

2CaO2 + 2H2O →→→→ 2Ca(OH)2 + O2

� Sodium Carbonate Peroxihydrat

2Na2CO3⋅⋅⋅⋅3H2O2 →→→→ 2Na2CO3 + 3H2O2

Oxygen Delivery

� Oxygen from air (20.9% O2) has limited water solubility 10 mg/L

� 100% oxygen provides 40-50 mg/L dissolved O2

� Hydrogen peroxide provides 480 g/L dissolved O2 (theoretically)

Alternative Electron Acceptors

� Nitrate (very soluble)

� Chelated ferric iron

� Sulphate

Stoichiometric Factors

O2 NO3- Fe(III) SO4

2- CO32-

32 62 56 96 44

Benzene 78 30 3,1 4,8 21,5 4,6 2,1

Toluene 92 36 3,1 4,9 21,8 4,7 2,2

Ethylbenzene 106 42 3,2 4,9 22,1 4,8 2,2

m-Xylenes 106 42 3,2 4,9 22,1 4,8 2,2

Naphthalin 128 48 3,0 4,7 20,9 4,5 2,1

Phenanthrene 178 66 3,0 4,6 20,7 4,4 2,0

Pyrene 202 74 2,9 4,5 20,4 4,4 2,0

TPH1 254 110 3,5 5,4 24,3 5,2 2,4

<CH2O> 30 4 1,1 1,7 7,4 1,6 0,7

“Utilization Factor” [g TEA/g Substrat]

1) Alkane n-C18 is assumed as "representative" TPH molecule

Contaminant

Molecular

weight

[g/Mol]

Need of

Electrons for

Complete

Oxidation

[mol e-/mol

Substrate]

Terminal Electron Acceptors (TEA)

Molecular Weight [g/Mol]

Substrates (anaerobic)

Molasses

(final syrup of sugar production)

� ca. 50 % Sugar

� ca. 30 % Protein, Nutrient Salts

� ca. 20 % Water

MolassesLactateWhey

Soluble Substrates „Slow Release“ Substrates

HRC®

Nutrient Oil SuspensionCAP-18®

Initial Situation

Principles of Biodegradation

In-situ Reaktive Zone (IRZ) and Substrates

Injection Technology

Case Study

Mobile Injektion System

Interference of Injection Volume and Frequency

λλλλSubstate = 0,035 d-1 (e.g. Molasses)

Soluble and Slow Release Substrates

A

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jáåáã~ä=ëìÄëíê~íÉ==ÅçåÅÉåíê~íáçå=íç=âÉÉé=ÇÉÖê~Ç~íáçå=êìååáåÖ

B

päçï oÉäÉ~ëÉ=pìÄëíê~íÉë

pçäìÄäÉ pìÄëíê~íÉë

Radius of Injection (ROI)

Desired ROI

Injection Well

rinj

M

inj

injh

Vr

θ⋅⋅π=

Aquifer Matrix – Mobile and Immobile Fractions

Migratory Wat

er

Static Water

Organic Matter

Movement

Residual NAPL

Soil Particle

Oxygen Consumption

0

5

10

15

20

25

30

35

40

45

0 5 10 15 20 25 30 35Remediation Time

Respir

ation R

ate

'

Oxygen

limited

Carbon

limited

Oxygen Delivery and Oxygen Consumption

10

50

235

470

0

100

200

300

400

500

Co

ncen

trati

on

[m

g/L

]

Oxygen Input

Saturation

with Air

Saturation with

Technical

Oxygen

Addition of

H2O2

(500 mg/L)

Addition of

H2O2

(1000 mg/L)

Formation of Oxygen Bubbles

not contaminated

contaminated

O2-Bubbles

nutrient salt solution

IRZ Remediation Concept

0 1 2 3 4 5 6

Migration Time (Years)Reactive Zone

Desorption Zone

1 12

Retardation of the Plume Extension

Co

nce

ntr

ati

on

in

Wate

r

Distance [m]

KOC = 265 L/kg

fOC = 0,001

VA = 1 m/d

KOC = 265 L/kg

fOC = 0,001

VA = 1 m/d

Symmetric Retardation after Source Removal

Groundwater Migration

100 Days 500 DaysC

on

cen

trati

on

in

Wate

r

Distance [m]

KOC = 265 L/kg

fOC = 0,001

VA = 1 m/d

KOC = 265 L/kg

fOC = 0,001

VA = 1 m/d

Growth of the Clean Water Front

VC = Velocity of the clean water front [m/d]

VA = Groundwater flow velocity [m/d]

RC = Composed retardation factor* [-]

C

AC

R

VV =

*Sorption onto the soil matrix + diffusion from static water

Determining Remediation Efficiency Requires Pilot Tests

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łdêçìåÇï~íÉê#

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fåàÉÅíáçåEłoÉ~ÖÉåí#F

Initial Situation

Principles of Biodegradation

In-situ Reaktive Zone (IRZ) and Substrates

Injection Technology

Case Study

Case Study

� Contamination with Dowtherm(Biphenyl and Diphenyl Ether) (Thermo Oil)

� Confined Aquifer

� Source Zone below building (KLP 1)

� Groundwater Fluctuation Zone

� Clay layer contains free product phase

� Contaminated area approximately 400 m²

� Biogeochemical Baseline Monitoring: anaerobic, iron-reducing (Fetot: 5,9 mg/L)

Geological Cross Section

Pump Test

1

10

100

1.000

10.000

100.000

1.000.000

10.000.000

24. Mrz 28. Mrz 1. Apr 5. Apr 9. Apr

Concentr

atio

n [µg/l]

Biphenyl

Diphenylether

1

10

100

1.000

10.000

100.000

1.000.000

10.000.000

24. Mrz 28. Mrz 1. Apr 5. Apr 9. Apr

Concentr

atio

n [µg/l]

Biphenyl

Diphenylether

1

10

100

1.000

10.000

100.000

1.000.000

10.000.000

24. Mrz 28. Mrz 1. Apr 5. Apr 9. Apr

Concentratio

n [µg/l]

Biphenyl

Diphenylether

KLP 1

Sand/Gravel

Clay

Back Fill

13

4,6

3,5

4,0

1,0

7,5

KLP 1

13

4,6

3,5

4,0

1,0

7,5

Back Fill

Clay

Sand/Gravel

KLP 1

13

4,6

3,5

4,0

1,0

7,5

Sand/Gravel

Clay

Back Fill

Diffusion Groundwater Flow Hydraulic Pressure

Aerobic IRZ with Horizontal Wells

KLP 1

13

4,6

3,5

4,0

1,0

7,5

Sand/Gravel

Clay

Back Fill

Diffusion Groundwater Flow Hydraulic Pressure

Infiltration Tubes

Drausy-Tubes

High Pressure = small holes

Low pressure = large holes

→→→→ Constant dosing over large distances

The Site

Remediation Success

0

2000

4000

6000

8000

10000

12000

01.01.2003 01.01.2004 31.12.2004 31.12.2005 01.01.2007 01.01.2008 31.12.2008

Dip

hen

yle

ther

[µg

/L]

KLP 1

KLP 4

KLP 11

Start Remediation

Take Home Message

� Low cost injection technologies are available

� These can be used to treat non-chlorinated and

chlorinated contaminants

� The technologies are of interest for site owners,

consulting companies and regulators

� Further details may be provided on request

([email protected])

Imagine the Result

[email protected]

Tel.: +49(0)6151 - 388 - 327

Thank You for Your

Attention