Joakim Andersson
Thermally enhanced remediation
Karin Tornberg Emma Evertsson Ebba Svanström Helsinki
In Situ Thermal Desorption
Stockholm Aalborg
Tom Heron
Esbjerg
Århus København Odense Warszwa Kié Kiév
Poznan
Division Director, geologist
Krakó Krakóv
Sofia
1050 colleques 250 environmentalists
Important tools in the toolbox • Heavily contaminated source zones • Stringent remediation requirements • Fast clean-up • Large volumes • Clay/silts/fractured Source zone • Deep contamination • Many contaminants and mixtures
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Treatable contaminants
• • • • • • • • • • • •
Chlorinated Ethenes Oil products, BTEX Data on much of this in Coal Tar NIRAS’ and Krügers Creosote booth up stairs!! PAH’s, Naphthalene PCB’s Chlorobenzenes Pentachlorophenol (PCP) Dioxins Mercury Many pesticides Mixtures
Remediation Mechanisms
2
Mechanisms and values for TCE
• Vapor pressure increases •
• TCE: 18 times for 10 - 100 °C Henrys law constant increases • TCE: 12 times for 25 - 100 °C
• The enthalpy of sorption decreases Gas Phase
• TCE: 20 % from 1025- 100 °C
• Viscosity, interfacial 20 tensions and density Liquid reduced: ~ 1 – 2 times 15 R
Nafthalene
• In Situ degradation 5 • Boiling point in multiphase systemTCE and 0 10
0
steam-drive
20
40
60
Temperature oC
80
100
Boiling point in a two phase system 1,50 Water + PCE 1,25 Water Pressure (atm)
1,00 PCE 0,75 0,50 0,25
0,00 0
20
87 40 60 80 100 Temperature oC
121 120 140
3
Technologies
Important Heating Technologies - Summary
Steam
Electrical
SEE - heating governed by hydraulic conductivity – nonuniform steam flow
ERH - heating governed by electrical conductivity
ISTD/TCH - heating Conductive governed by thermal conductivity – nearly uniform distribution of heat
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In Situ Thermal Desorption and destruction Very Hot Thermal Destruction Zone
Volatilization and Destruction of Contaminants Target T: 100oC to 300oC 1 to 2 feet
300oC to 700oC Off-Gas Residence Time Several Hours
To Off-Gas Treatment Unit
1 to 2 feet
HeaterVacuum Well
HeaterOnly Well
Important design issues:
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Important design issues
• Goals / effect on risk or value • Time • Price • Liquid and vapor capture
• • • • • •
Condensation fronts Boiling water is expensive Temperature distribution Energy balance Organic rich soils Underground utilities / buildings etc.
Examples of completed projects
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Naval Air Station Alameda, Site 5, San Francisco Goal: MCL in soil and groundwater for BTEX og chlorinated solvents TCE: 2 mg/kg og 5 µg/l
After thermal treatment
TCE, BTEX, etc
Typical chromatogram: Soil before Steam
Motor oil
Courtesy of Kent S. Udell
UC Berkeley
ISTD – Free phase PCE in tight alluvial clay
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Results – Average concentrations 34,222
AVG Post Remedial Goals AVG Pre
35,000
Soil Concentration - ug/kg
30,000
25,000
20,000 17,000
15,000 6,650
10,000
1,055
5,000 2,000
PCE
Reductions:
2,000
12
0
99.96%
932 230
< RL
65
5
TCE
cis-1,2-DCE
VC
99.63%
99.03%
99.49%
Results are based on 17 pre-treatment and 64 post-treatment samples
Ongoing Danish Projects
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Knullen – Odense, Denmark Worlds first thermal remediation using af combination of steam and ISTD COC’s: PCE, chlorinated solvents (800 kg) TTZ Soil: Clay and sand Treatment interv.: 3 – 14 m.b.g. Area: 240 m2 Volume: 1.900 m3 Estimated cost: 15 mio. dkr Number of HV-borings:
45
Steam injection wells:
5
Steam extraction wells:
2
All wells installed under a building
Skuldelev – Denmark Full-scale design based on results from pilot test COC’s: PCE, chlorinated solvents (4000 kg) Soil: Clay and sand Treatment depth: 7,5 meters Area: 250 m2 Volume: 1.600 m3 Pilot test, Skuldelev
Estimated cost: 12 mio. dkr
ISTD-wells:
53
Vacuum wells:
21
Water extraction wells:
3
Building
Lake
TTZ Sheet piling ISTD-heater Water extraction boring Monitoring well, Skuldelev
Vacuum boring
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Ongoing projects
Netherlands – Confidential site
Reerslev – Denmark
COC: Diesel (mass currently unknown)
COC: PCE – 10.000 kg
Soil: Fractured limestone
Soil: Clay
Treatment depth: 6,5 meters
Treatment depth: 8 meters
Area: 100 – 3.500 m2
Area: 900 – 4.700 m2
Design based on treatability study – indicated remediation efficiencies better than 99.9% at treatment temperatures between 100 and 200 °C. Flow of nitrogen
Condensing system
Oven
Temperature measurements
Test setup – laboratory experiments
Thank you and:
? ?
? ?
[email protected] +45 87323256 +45 21418302
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Physical processes/changes (below 120 °C)
Oil based LNAPL
Chlorinated solvents
Creosote
Coal tar
PCB
Comment
Vapor pressure increase factor 20-40
20-40
20-40
20-40
20-40
Abundance of data in literature
Solubility increase factor
1.5-3
10-1000
10-1000
10-1000
10-20
0-10
0-10
0-10
Component property
2-100?
Henry's constant increase factors Viscosity reduction factor
2 to 100+
1.3-3
5-10
20-100+
3-100
Interfacial tension reduction factor
