CCA-Treated wood disposed in landfills and life-cycle trade-offs with waste-to-energy and MSW landfill disposal

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 m(3). 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.

Soil arsenic surveys of New Orleans: localized hazards in children’s play areas

“…Scope of arsenic toxicity in relation to CCA-treated wood From the 1950 introduction to 2005, approximately 275 million cubic meters of CCA-treated wood were produced and marketed in the US (Bancca 2005;Jambeck et al 2007). Converted into board feet (116,538 million b-ft) this quantity of wood (at 16,000 b-ft per 2,300 ft 2 home) is sufficient to build 7.3 million homes.…”

“…In 2003, because of the inherent dangers of CCA wood products, the EPA initiated a ban for residential use in the US. The ban did not apply to CCA-treated wood used for electrical and telephone poles or railroad ties, and thus an additional 4 million cubic meters of CCA-treated wood remain in production per year (Christen 2006;Jambeck et al 2007). The initial samples (N = 4) were from two play areas.…”

“…CCA-treated wood contains the most toxic inorganic form of As. Use of CCA began in the US during the early 1950s, and by 1974 CCA-treated wood became extensively marketed in the US for residential applications, and use rapidly increased to peak production in the 1990s (Jambeck et al 2007;US EPA 2008). CCA-type C treated wood was commonly used in the US until the voluntary cessation of production for all but commercial uses in 2003.…”

Optimization of a chemical leaching process for decontamination of CCA-treated wood

“…However, since governmental organizations define treated wood material as non-hazardous waste, it is regularly dumped into landfills even if it is highly susceptible to metal-leaching and dispersion [9]. Townsend et al [10] showed that the quantity of metals leached from CCA-treated wood can exceed the toxicity guidelines generally used for hazardous waste identification.…”

Application of a CCA-treated wood waste decontamination process to other copper-based preservative-treated wood after disposal

“…As the wood reaches its end-of-life, it is usually disposed off in landfill or burning facilities. Neither disposal option is ideal for CCA treated wood as there are risks of dispersion of arsenic, chromium and copper in the environment [8,9]. New sustainable management strategies need to be developed.…”