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CCA-Treated Wood Disposed in
Landfills and Life-cycle Trade-Offs With Waste-to-Energy and MSW
Landfill Disposal.
Jambeck, J., Weitz, K.,
Solo-Gabriele, H., Townsend T., Thorneloe, S.
Waste
Management, 27(8):S21-S28.doi:10.1016/j.wasman.2007.02.011
Abstract : Chromated
copper arsenate (CCA)-treated wood is a preservative treated
wood construction product that grew in use in the 1970s for both
residential and industrial applications. Although some countries
have banned the use of the product for some applications, others
have not, and the product continues to enter the waste stream
from construction, demolition and remodeling projects. CCA-treated
wood as a solid waste is managed in various ways throughout the
world. In the US, CCA-treated wood is disposed primarily within
landfills; however some of the wood is combusted in
waste-to-energy (WTE) facilities. In other countries, the
predominant disposal option for wood, sometimes including CCA-treated
wood, is combustion for the production of energy. This paper
presents an estimate of the quantity of CCA-treated wood
entering the disposal stream in the US, as well as an
examination of the trade-offs between landfilling and WTE
combustion of CCA-treated wood through a life-cycle assessment
and decision support tool (MSW DST). Based upon production
statistics, the estimated life span and the phaseout of CCA-treated
wood, recent disposal projections estimate the peak US disposal
rate to occur in 2008, at 9.7 million m3. CCA-treated
wood, when disposed with construction and demolition (C&D)
debris and municipal solid waste (MSW), has been found to
increase arsenic and chromium concentrations in leachate. For
this reason, and because MSW landfills are lined, MSW landfills
have been recommended as a preferred disposal option over
unlined C&D debris landfills. Between landfilling and WTE
for the same mass of CCA-treated wood, WTE is more expensive
(nearly twice the cost), but when operated in accordance with US
Environmental Protection Agency (US EPA) regulations, it
produces energy and does not emit fossil carbon emissions. If
the wood is managed via WTE, less landfill area is required,
which could be an influential trade-off in some countries.
Although metals are concentrated in the ash in the WTE scenario,
the MSW landfill scenario releases a greater amount of arsenic
from leachate in a more dilute form. The WTE scenario releases
more chromium from the ash on an annual basis. The WTE facility
and subsequent ash disposal greatly concentrates the chromium,
often oxidizing it to the more toxic and mobile Cr(VI) form.
Elevated arsenic and chromium concentrations in the ash leachate
may increase leachate management costs. Keywords :
Leachate, Arsenic, Chromium |
