The absence of commercial facilities to recycle or recover value from wood treated with metal-based wood preservatives at the end of its service life is one of the most significant negative points in the generally positive life cycle analysis of treated wood. Wood treated with carbon-based preservatives (metal-free) may be far easier to recycle or recover value from since the preservatives are relatively vulnerable to thermal, chemical and biological breakdown. As a result they might be destroyed by kraft pulping, combustion or composting of treated wood. The present research evaluates the use of carbon-based preservative-treated wood in these processes.
Kraft pulps produced from wood freshly treated with recommended loadings of carbon-based preservatives contained significant quantities of didecyldimethylammonium carbonate (DDAcarbonate), propiconazole and tebuconazole. However, lower preservative concentration in the wood and intensive pulping may be able to produce pulps without detectable preservatives. The azoles were also detected in significant quantities in the black liquor (DDAcarbonate was not analysed in black liquor).
No azoles were found in the ash produced from combustion, but significant quantities were detected in the filtered smoke. DDAcarbonate was not detected in the filtered smoke. Analysis of DDAcarbonate in ash was inconclusive.
A composting experiment has been set up and is in progress. Data on preservative breakdown during composting is expected next year.
A number of preservative manufacturers have developed carbon-based preservatives designed for above ground uses. To fulfill the requirements of Canada's Pest Management Regulatory Agency for performance data under Canadian conditions, a prototype accelerated field simulation test method had been developed and successfully tested. This report covers the design and construction of a purpose built chamber in which to conduct this test.The temperature- and humidity-controlled chamber contains metal racks, fitted with drip trays, on which samples can be placed and intermittently sprayed with deionized water to simulate rainfall. Sporing cultures of wood rotting fungi will be attached to the ceiling and outdoor air is brought in, heated and humidified, at intervals to introduce natural airspora. The chamber has been constructed to specifications.
The transition of the wood preservatives industry from metal-based preservatives to carbon-based preservative systems requires the development of new analytical techniques. Liquid Chromatography/Mass Spectrometry (LC/MS) is a key method for the identification and quantification of most carbon-based wood preservatives and their degradation products. To enhance our capability to measure these preservatives, a system was needed that could detect low concentrations of preservatives, ionize all compounds of interest, and provide extensive qualitative information. The LTQ XL LC/MS from ThermoFisher was identified as the system best able to meet these needs. This instrument was purchased and installed and methods were developed to separate and quantify three carbon-based preservatives commonly used in emerging wood preservative formulations.
Segments of the wood preservation industry are transitioning from metal based preservatives to new carbon-based preservatives perceived as environmentally preferable. To ensure a successful transition there is a need to identify the fungi capable of detoxifying and decaying wood treated with new formulations. Traditional identification of fungi was based on morphological, physiological and biological characteristics of cultures grown on artificial media. These methods are time consuming, difficult, require extensive training and still may not lead to fungal identfication. In most laboratories fungal identification now relies on a combination of traditional techniques and molecular techniques. Provided that there is necessary equipment available, molecular identification is quick, requires less training and is often more accurate than traditional methods or significantly complementary to traditional methods. In addition, molecular methods are also used to quantify fungal colonization of wood, to study the effect of wood preservatives on fungi and succession in the decay process. FPInnovations did not have this molecular capability but realized it was critical for identification and investigation of detoxifier and decay fungi on treated wood. With funding from the Transformative Technologies program, FPInnovations identified and obtained the necessary equipment and set up appropriate lab spaces to conduct this work. Basic protocols have been put in place, staff trained and the techniques are now in use. This report addresses the progress made in laboratory set up, protocol development and molecular research now underway at FPInnovations.
