Supercritical Water Treatment of
Creosote-Treated Wood Waste
Todd F. Shupe
W. James Catallo
IUFRO All Division 5 Conference
29 October – 2 November, 2007
Taipei, Taiwan
Main Research Objective

To develop a complete closed-loop recycling
system to achieve zero discharge of wood
preservatives into the waste stream. The system
must be economically viable and environmentally
friendly.
Recycling Potential
•There is a need for extensive research into ways of
reducing, reusing, recycling, and disposing of treated
wood in environmentally acceptable ways (Cooper 1994).
The Present

It has been estimated that about 5 million
tons of spent preservative treated wood is
disposed of annually into landfills in the
United States (Falk 1997).
Industrial Applications
“Green” recycling
 Rural economic development

Preservatives Studied

Copper chromium arsenic (CCA)
 Creosote

Oil-borne pentachlorophenol (penta)
Supercritical Water

Supercritical (SC) water (>374 oC/221 bar)
under anoxic and reducing conditions has
been used for a variety of synthetic
chemical transformation/recycling purposes.
Supercritical Water

The SC phase is one of the most energetic
and chemically dynamic conditions known
for aqueous systems, including a) liquid
water under conditions normally observed,
b) very high pressures and, c) superheated
steam.
Creosote Methods
1mm particle size
 pH 10
 400  10 oC/280 bar for 15 hrs. including
heat up and cool down

Fresh Creosote
Weathered Creosote
After 12 h SC Treatment
Fresh Creosote
“Regenerated” Creosote
After 12 h SC Treatment
Weathered Creosote
Creosote Results

During treatment, the creosote-derived
hydrocarbon residues in the wood were
nearly completely (>99%) recovered and
the wood itself was transformed into a
mixture of hydrocarbons including
substituted benzenes, phenolics and light
PAHs.
Creosote Results

These wood-derived transformation
products served to reconstitute the "light
end" of the creosote, which largely had been
lost while in service.
Creosote Results

Thus, the hazardous waste (creosote
hydrocarbon mixture) was recovered, and
the solid waste (wood) was transformed into
a complimentary product mixture in a single
pass. Solid residues after 12-20 h of
treatment were <2% w/w.
Conclusions

Creosote - The hazardous waste (creosote
hydrocarbon mixture) was recovered, and
the solid waste (wood) was transformed into
a complimentary product mixture in a single
pass forming a “recycled” creosote.
Current Research
Detoxification of mixed treated wood types
(no sorting of different preservatives)
 Kinetics
 Gas phase analysis
 Efficacy testing of “recycled” creosote

Contact Us
School of Renewable Natural Resources
Louisiana State University
Rm. 111 Renewable Natural Resources Bldg.
Baton Rouge, LA 70803-6202
phone: (225) 578-6432
fax: (225) 578-4251
http: http://www.rnr.lsu.edu/
e-mail: tshupe@lsu.edu
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