A New Recycling Process to Give Wood a New Lease of Life

Let’s carry out a simple test. You have five seconds to list all the recycling containers that come to mind. Ready? It shouldn’t be that difficult: plastic, paper, glass, organic waste… That seems quite sustainable. Maybe, if you have a couple more seconds, you can come up with a few more, such as oil banks or battery collection points. However, there’s something missing—wood. It could be said it’s recycling’s ugly duckling. Currently, the main way of disposing of it is mainly by using it as fuel in power-generation plants, dumping it in landfill sites or, in the best scenario, transforming it into chipboard. Luckily, an EU-backed project aims to change this and open up new possibilities for recovered wood. CaReWood (Cascading Recovered Wood) is the acronym chosen for a range of procedures to recover and reuse large pieces of wood, giving them a second opportunity.  

But why isn’t there a greater number of wood recycling schemes? Well, besides technical and cost reasons, the main obstacle lies in the veneers and chemical treatments usually applied, frequently with hazardous substances such as DDT or PCBs, which were widely spread in the past. PVC particles or remnants of lead-based paint can also be present. European regulations require these materials to be destroyed as they can be a health hazard. In Germany, one of the European countries were reforestation schemes have taken root more firmly, the Fraunhofer Institute for Wood Research WKI, together with fifteen other partners from five European countries, has developed a set of protocol to salvage large pieces of wood, usually poles, crossbeams and the like. At present, the process is comprised of two stages:

1. Detection of hazardous chemical substances and stress tests. This initial stage uses advanced spectroscopy, X-ray fluorescence, chromatography and spectrometry techniques to assess the amount of contamination and the depth to which the pollutants have penetrated the material. Some of these methods allow to detect wood preservatives, while others are better suited to discover traces of heavy metals. Following this process, the scientists also check the bending resistance of the wood and its mechanical stability.
2. Decontamination. Once the pieces have passed the first exam, it’s time to begin the cleaning process. The researchers from the Fraunhofer Institute have proved that the pollutants rarely go a few millimeters beyond the surface. So another set of techniques have been developed to clean the wood, including rotating brushes, sand-blasting with different abrasive media and sawmilling among others.

The results have been quite encouraging and a pilot test has already been carried out to help with the restoration of a 150-year-old teak bridge in Myanmar, the longest of its kind in the world. The support posts, some of them measuring ten meters in length, are being reused as handrails or rest benches along the 1.2 kilometers of the structure.  

Germany will soon pass new regulations with a stronger emphasis on salvaging wood instead of destroying it by the end of its service life. Hopefully these rules will also be matched by other countries in the rest of Europe.

The advantages of CaReWood, the new wood recycling system

This ambitious project enjoys several advantages, some of them more noticeable than others.

• The deforestation in Europe and other continents could be slowed and reversed owing to the reduced consumption of wood.
• The burning of contaminated wood is avoided.
• Reduction of waste.
• Recovery of old wood, often with higher resistance and durability, as a few decades ago it came from slow-growth trees.

Fuente: Fraunhofer Institute