Monitoring wooden materials for recycling

Appropriate recycling of matter is a challenge. The recycling process involves technical, economical, chemical, educational aspects, which have to be carefully considered. Wood is a natural product, spontaneous in its re-production, economic in its use, easy to be crafted, elastic, strong, light, naturally biodegradable, carbon neutral. The engineered products made of wood or applied to wood, such as panels, glulam, cross laminated timber, wood preservatives, glues or coatings, dramatically increase the wood performances. At a price. These wood based products may be no more biodegradable or combusted with the same neutral footprint on environment, atmosphere or biosphere. Italian wood recycling system manages each year a million of tons of post use wood. The possible end life destinations of all this wood and wood-based materials are recycling in particleboards, repairing, combustion, incineration, landfill, biodegradation. The system is successful in coordination of the actors (production enterprises, municipal solid waste platforms, recycling collectors, recyclers), but concern is seen in the amount of chemical analyses done per year. The analyses are done, according to law, once per year per recycling platform, and this seems not enough for a so heterogeneous material like post use wood. Analyses performed according to law should be done with expensive techniques, but other techniques are accepted after validation. This thesis experimented the application of 2 techniques in monitoring solid wood and wood based materials. The X-ray fluorescence (ED-XRF) and Fourier Transformed Medium Infrared (FT-IR-ATR) are expected to be faster and cheaper, even if not as accurate, than consolidated methods (Atomic Absorption Spectroscopy or Inductively Coupled Plasma Spectrometry). In order to apply these analytical techniques to wood matrices, a detailed batch of preliminary tests has been performed, especially regarding the use of the ED-XRF. A sampling of post-use wood and wood based materials coming either from recycling platform either from wood enterprises and research centers have been performed. A sampling of biomass coming from forests of Europe has been performed as well. The experimental plan performed analysis on natural wood and known contaminants, in order to establish a background of known values. An experimental pollution of biomass was performed as well in order to verify the ability of monitoring pollutants over time. The survey on waste wood was intended to verify the capability of the system to detect hazardous materials, and to trace them eventually within the law thresholds. A cross comparison of few specimens has 9 been done together with the use of the innovative ED-XRF technique and a consolidated one. The monitoring of pollutants experimentally applied over time is successful, being able to distinguish experimentally polluted wood up to 20 months from contamination. The use of FT-IR-ATR technology to detect unknown pollutants resulted to be fair. The preliminary tests on the use of ED-XRF defined the limits and capabilities of the system. The instrument was capable of monitoring waste wood in its chemical composition of elements with atomic mass higher than the one of potassium. The survey on wood waste showed that 84 % of specimens are compliant with the European normative, and therefore present low or no pollution. The specimens resulted more polluted were those originated from furniture, followed by buildings and finally packaging. The wood based materials (panels) resulted to be more polluted than the solid wood. The wood based material resulted to be more polluted was the particleboard. Very high concentration of Cl and Cr were found in few specimens, and pretty often the concentration of Pb was high. Wood recycling is a process that deals at the same time with not polluted natural wood, which could be used in manufacturing including combustion or panels, and hazardous materials, whose re-use must be stopped. Even if pretty effective technologies for chemical or physical removal of pollutants exist, the most effective way to reduce hazardous contaminants in waste wood is to avoid the use of these products during manufacturing. More care should be taken in avoiding wood contamination during manufacturing, for example choosing innovative eco-friendly manufacturing processes, and more care should be taken in wood waste analyses prior to further processing.