Download - IHA/pm1 Site remediation Overview of site remediation techniques Typical application Pros/cons
IHA/pm 1
Site remediation
Overview of site remediation techniques
Typical application
Pros/cons
IHA/pm 2
In – situ treatment
• Where: • Close to / under buildings
• Deep contaminations
• At suitable geology – sand/gravel is best!
• Important aspects:• Physical/chem. properties of chemical (phase
distribution)
• Geology
• Biodegradability of chemical
Determine (potential) transport
When excavation is difficult
IHA/pm 3
E.g. oil pollution
• Phase removal?• Biological treatment (in situ / of removed phase)?
IHA/pm 4
The typical approach
1: Initial hot-spot treatment: Suction pipes for free phase (2 – 3 m deep): water + air. Coalecence for free phase + GAC/oxidation
2: Mapping of geology and contamination distribution. Strategy for final treatment.
3: Final treatment (Biological methods, ventilation, ?). Typical operation for 4 – 6 years.
4: Monitoring & control phase.
IHA/pm 5
Strategy – remediation method
Phase (water / gas) extraction + treatment
In situ: destruction
Mass removal:
Mobility reduction (water & air) or fixation in solid phase
Chemical oxidation
Natural /stimulated biodegradation
Vadose zone: Vacuum ventilation, steam stripping, termal desorption, forced leaching.
GW zone: Pumping, In well stripping, sparging.
(e.g. precipitation of metals)
IHA/pm 6
In situ methods – vadose zone
• Natural decomposition • Stimulated biological soil treatment • Soil vapour extraction (vacuum ventilation) *• Forced leaching (*)• Heat enhanced stripping *
• Chemical oxidation (O3 , KMnO4 ..) *
• Phyto remediation• Immobilisation
Alternative. Doing nothing – natural decomposition, leaching…
IHA/pm 7
In situ methods – ground water zone
• Groundwater pumping and treatment *• In well treatment (stripping) *• Sparging (air, ozone, Bio) *• Biological methods (bioaugmentation, reductive
dechlorination) *• Chemical oxidation *• Reactive walls (Fe0) *
Clay soil: + fracturing (hydraulic / pneumatic)
Combination of methods!
IHA/pm 8
Control / remediation:Remedial pumping / “Pump & treat”
IHA/pm 9
Treatment of extracted liquid
• NAPL phase separation (coalescence) petrol, PCE..• Dissolved organic matter:
• Biological treatment. Biological filters (phenols, oil, cyanide, … )
• Chemical oxidation. Ozone, H2O2 (Fenton reagent), KMnO4, …
• Small concentrations. GAC filtration
• Heavy metals: precipitation (pH + complexing agents)
Treated water. Re-infiltration or to sewer
IHA/pm 10
Vadose zone + volatiles + sand:
Vacuum ventilation
• In unsaturated zone - typical for small quantities of chlorinated solvents og light hydrocarbons
• Initial effect, but then slow. Takes long time to have significant mass removal.
• (cheep alternative: passive ventilation – barometric differences driving force.. )
IHA/pm 11
Vacuum ventilationon/off operation – rebounce:
Time
Con
cent
ratio
n
Fro
m w
ww
.avjinfo.dk T
ekn
ik & ad
m n
r 4/2003
IHA/pm 12
Near GW table + volatiles + sand:
Air sparging
“Rule of thumbs”:
• If KH > 0.01 (BTEX KH = 0.1 – 0.2 , MTBE KH = 0.02)
• Potentially 90 % mass removal (in sand)• Vacuum flow 2 x sparge flow
IHA/pm 13
In well stripping
• Intermittent operation to avoid same water drawn as infiltrated.
• 0 – 5 m3/h per filter• 10 – 20 % quick
removal (mass removal) then slow biological process
• Nutrients can be added.• Radius of influence 2 –
3 m
IHA/pm 14
Treatment of extracted air
Organic chemicals: • Biological treatment in filters (bark, compost.. For
somewhat water soluable compounds)
• Incineration (organic matter in high concentrations)
• GAC filtration (non-polar substances)
• Heavy metals (As, Hg): GAC absorption
IHA/pm 15
GW plume:
Permeable reactive barriers
Literature:
“Design guidance…” A.Gavasker et al, 2000, US Air force recearch lab.
“Economic analysis of ..PRB..” US EPA , 2002.
Fe (o)
KMnO3
GAC
• Hot Water Flushing
• Steam Enhanced Extraction, SEE
• Electrical Resistivity Heating, ERH
• In Situ Thermal Desorption, ISTD
• Radio Frequency Heating, RFH
hotspot:
Thermally enhanced methods
(Smith et al. 1994)
150 200 250 300
PC
Bs,
Dio
xin
s
Naphth
ale
ne
Merc
ury
Vapor pressure with temperature
IHA/pm 18
500
400
300
200
100
Benz(a)pyrene
Fluorantene
Phenantrene
PCB’s
NafthalenePhenole
XylenePCE, Toluene
TCEBenzene
TCA
Ho
t W
ater
Flu
shin
g
Temperature oC
Ste
am S
trip
pin
g, S
EE
Rad
io F
req
uen
cy H
eati
ng
, RF
H
Th
erm
al C
on
du
ctio
n, I
ST
D
Ele
ctri
cal H
eati
ng
, ER
H
Hot Water Flushing
Steam stripping (SEE) e.g. “Outside – in” approach
Steam stripping (SEE)
“Inside out” design
ElectrodeExtraction well
Electrode
Electrical Heating, ERH
Energy consumption (kWh/m3)
Initial water content
100 % 80 % 10 % 0 %
Heating to 100 ºC, wet 80 61 47 43
Heating to 100 ºC & evaporating all porewater
299 171 69 43
Heating to 200 ºC347 219 117 91
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Biodegradation, e.g.:
Reductive dechlorination
• What: destruction of chlorinated org. solvents(PCE, TCE, VC…)
• Where: in GW zone. At hotspot and in plume.porous soil (contact)
• How: anaerobic biological process• Bioaugmentation. Supply of dehalococoides bacteria• Decomposition process: PCE – TCE – DCE - VC – Ethylene
• The chlorinated organic substance acts as electron acceptor (like O2). The (Electron) Donor must be supplied: H2 .
• anaerobic conditions must be created. Reasonably fast (months / year)
IHA/pm 25
Degradation of chlorinated solvents
ReductiveDehalogenation
Anaerobicoxidation
Aerobicoxidation
Aerobiccometabolism
PCE +TCE + +Dichlorethylene + + + +Vinylchloride + + + +Trichloroethane + +Dichloroethane + + +Chloroethan + +Tetrachloremetha. +Trichloromethane + +Dichloromethane + + +
Boettcher & Nyer, In Nyer et al (2001) In situ treatment technologies, Lewis publishers.
Feb. 2006 IHA/pm 26
Strongly reducing
PCE TCE DCE VC Ethene
AerobicCH4 mv.
AerobicStrongly reducing
Bioaugmen-tation
Dehalococcoides
Sequential redox environment
In real life!
IHA/pm 27
In real life: PCE and TCE in aquifers
VadoseZone
Flow
Chlorinated SolventsCo-disposed withsubstrates (e.g., BTEX,isopropanol, acetone,etc.)
Type I Zone: Added Substrates -High Dechlorination
Rates
Type II Zone: Natural Substrates -
Moderate to LowDechlorination
Rates
Type III Zone: No Substrates -
Low DechlorinationRates
Strongly reducingAerobic
IHA/pm 28
E = Excellent, G = Good, P = Poor
In-situ chemical oxidation - oxidants and contaminant susceptibility
Activated persulfatePersulfatePermanganate
Fenton:H2O2 + Fe O3
IHA/pm 29
Fentons reagent (Fe + H2O2)
Trailer with H2O2
Injection probes
IHA/pm 30
Tank with O2
Injection probes
Health issues
Photos taken by:
Watertech, DK
Ove Arkil, DK
Ozone oxidation
Feb. 2006 IHA/pm 31
Case: Remediation of dry cleaning facility By: NIRAS A/S
Dry cleaning facility in Odense, Denmark
Contaminant characteristics:
Soil: Up to 50 mg/kg DW PCE
Groundwater: Up to 58 mg/l PCE
Soil vapor: Up to 2.000mg/m3 PCE
Contaminant mass estimated to 100 kg PCE
Geological characteristics:
Moraine clay with interbedded layers of sand
Site location
IHA/pm 32
1-10 mg/ m3
> 100 mg/ m3
10-100 mg/m3
Getting the overview – making the model
IHA/pm 33
Groundwater contamination
Dry cleaning facility
Source area >10.000 g/l
1.000-10.000 g/l1-1.000 g/l
IHA/pm 34
B1 B2 B3
Geological logs
IHA/pm 35
Sandy zones
Water table
Moraine clay
B3
Conceptual model
IHA/pm 36
1,9
Uncontaminated soil
Water table
4,2
1,5
Contaminated soil
10,44
6,6
9,41
11,47
6,58
8,53
8,35
8,99
6,02
9,46
m b.s. Average: 9 g KMnO4 / kg soil
Majority of NOD originates from oxidation of natural organic matter
Treatability study: Natural Oxygen Demand (NOD), g-KMnO4/kg
IHA/pm 37
Laboratory results
• Average diffusion 3 cm per 50 days ~ 20 cm/year
Oxidant
Transparent jar
Intact core
Laboratory setup
• Intact cores, 20 cm
Treatability study: Diffusion into clay matrix
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Remediation concept
Pea gravel and KMnO4 backfilled
Excavation of 25% in source zone
• Excavation of 25 % of the source zone (400 m3 soil)
• Chemical oxidation in source zone and adjacent soils
• Mixture of pea gravel and KMnO4 backfilled
• 12.000 kg KMnO4 (s) installed
• System installed for further addition of liquid oxidant (NaMnO4)
IHA/pm 39
Dissolved contamination
Moraine clay with sandy zones
PCE diffused into matrix
Concept: Installation of permanganate in fractured clay
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Excavation and installation of KMnO4
Feb. 2006 IHA/pm 41
Excavation and installation of KMnO4
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Installation of a mixture of KMnO4 and pea gravel
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Injection wells in source zone
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Monitoring
• PCE
• KMnO4
• Conductivity
• Cl-
• Color
IHA/pm 45
Dry Cleaning facility
Groundwater flow
6 MonthsGroundwater
flow
12 Months
Dry Cleaning facility
A1
Dry Cleaning facility
Groundwater flow
3 Months
Distribution of oxidant
IHA/pm 46
46
110
140
240
April 2003
[µg PCE/l]
-69%110350M1.3
130
330
1800
January 2003
[µg PCE/l]
+385%630M1.5
-48%170M1.2
-99%11M1.1
ChangeNovember 2003
[µg PCE/l]
Well
Clean up efficiency (water samples)
IHA/pm 47
Permanganate in soil
Feb. 2006 IHA/pm 48
Fractures in till clay
From lecture by Knud Erik S. Klint, GEUS. At ATV meeting Vingsted 2006
Feb. 2006 IHA/pm 49
Makroporezones in moraine till
IHA/pm 50
0
1
2
3
4
5
6
7
8
9
10
1,E-09 1,E-08 1,E-07 1,E-06 1,E-05 1,E-04
HYDRAULIC CONDUCTIVITY (m/s)
DE
PT
H (
m)
Serie1
Makropore zonerMakropore zonerMacropore zone 1 Oxidized, no CaCO3, many biopores
Makropore zone 2 Oxidized, CaCO3 rich
Makropore zone 3 Reduced, CaCO3 rich
Bulk hydraulic conductivity (fractures + matrix)
IHA/pm 51
LNAPL- distribution in clay till. Location Ringe, Fyn.
IHA/pm 52
Hydraulic fracturing - principle
1) Drill well, Insert casing
2) Displace drive point – expose borehole
3) Notch the borehole (cut a fracture)
4) Propagate fracture with slurry and fluid
From: http://www.frx-inc.com/createfracture.html
Feb. 2006 IHA/pm 53
Contaminatedarea
Fracturing & stimulation
From: Bertil Nielsson et al “In-situ oprensning af organisk forurening I moræneler”, ATV vintermøde 7/3 07.
IHA/pm 54
From: C.E.Riis & A.G.Christensen “Pilotforsøg med pneumatisk frakturering” ATV Vingstedmøde, 2006
Pneumatic fracturing