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.
In April 2008, the State of California adopted an airborne toxic control measure (ATCM) to reduce formaldehyde emissions from composite wood products, proposed by the California Air Resources Board (CARB), part of the California Environmental Protection Agency. Phase 1 started in January 2009, and at the end of the implementation, in July 2012, formaldehyde emission limits will range between 0.05 and 0.13 ppm, depending on the type of products, based on the ASTM E 1333 Large Chamber Method.
These new limits are in the order of the limits of detection of the current analytical methods presently used, and rendered the chromotropic acid reaction, on which the ASTM E 1333 is based, with a limit of detection of 0.01 ppm less precise.
An alternative method to determine formaldehyde concentration in air has been developed to be used as part of the ASTM E1333 Large Chamber Method. 60 L of air are sampled through an impinger containing an acetylacetone-ammonia solution. The solution is then heated, and analyzed by fluorimetry using a Turner Quantech filter fluorometer equipped with a NB430 excitation filter and a SC500 emission filter. The test method is inexpensive, easy to use, compatible with the Large Chamber, Perforator and Desiccator Methods, and is very sensitive. The minimum detection limit (MDL) and the limit of quantification (LOQ) of this analytical method are 0.0004 and 0.0013 ppm, respectively.
La détermination de la teneur en humidité du bois est un facteur clé lors de toutes les étapes de transformation afin d’obtenir des produits de qualité, diminuer les pertes de matière première et minimiser les problèmes lors de l’utilisation finale. L’objectif de ce projet est de développer des procédures d’évaluation de la teneur en humidité des bois d’apparence pour les différentes étapes de transformation, soit de l’usine de sciage au séchoir, du séchoir à l’entrée de l’usine de transformation, en cours de transformation et de l’usine de transformation aux utilisateurs finaux.
L’utilisation de procédures d’évaluation de la teneur en humidité fiables, reconnues et éprouvées sera bénéfique aux manufacturiers et leurs relations d’affaires. Les relations entre les clients et les fournisseurs (internes ou externes) reposent sur la confiance mutuelle et la mesure de la teneur en humidité est une des principales causes de mésentente. De plus, une mauvaise évaluation de la teneur en humidité sur les produits semi-finis ou finis a des conséquences coûteuses pour les entreprises.
Une partie de ce rapport est consacrée aux notions de base car il est primordial de comprendre certaines propriétés physiques du bois pour interpréter des mesures de teneur en humidité, Parmi celles-ci, notons l’humidité dans le bois, la teneur en humidité d’équilibre, le gradient de teneur en humidité et le point de saturation des fibres. Il est aussi essentiel de connaître la relation entre les variations de la teneur en humidité du bois et la stabilité dimensionnelle des produits en bois, soit les notions de retrait et de gonflement.
Une autre partie décrit les trois (3) principales méthodes de détermination de la teneur en humidité, soit la méthode au four, par humidimètre à résistance et par humidimètre diélectrique et explique les différents facteurs qui affectent ces méthodes. Des procédures de base pour chaque méthode sont présentées et aussi adaptées pour tenir compte de l’état du bois (vert ou sec, brut ou raboté, empilé ou non, sur lattes ou solide, etc.) et de l’étape de production (usine de lattage, séchoirs, entrée de l’usine de transformation, réception de camion, produits finis, etc.). En dernier lieu, les notions de base de statistiques et d’échantillonnage sont abordées sommairement.
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.