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European Journal of Wood and Wood Products (2023) 81:557–570
of waste wood to the production of wood-based panel as well as its effects on the physical and mechanical proper- ties and formaldehyde emission of final products (Tables 3, 4). Due to the variety of materials and the effects of pos- sible contaminations, this paper presents an overview of the conducted waste wood research with the goal to answer the following questions: 1. Where do the waste wood materials come from and what are the target composites? 2. What are the challenges that recyclers are facing during the conversion of waste wood? 3. What is the concentration of recycled wood material in the new composite products and its consequences?
nowadays. Germany, Austria and Switzerland apply the same ordinance divided into four categories depending on the characteristics of the waste wood, namely AI, AII, AIII and AIV, whereas France, Belgium, Netherlands and Lux- emburg classified their waste wood categories with A, B, C and D (Jan 2019). UK, Sweden, Estonia and Spain have their own waste wood ordinances. In addition, many countries have not established waste wood ordinance. In this sense, it is difficult to trade different collected waste wood assort- ments between European countries. Despite the difference in waste wood management, the recycling rate of waste wood varies from country to coun- try in material and energy uses. For instance, in European countries, for decades, energy utilization of waste wood exceeds material utilization, accounting for 60–95%. Swe- den, Switzerland, Norway, Netherlands, and Finland are the top leading European countries, which share high waste wood portion for energy purpose, ranging from 85 to 95% (BAV e.V. 2021). In the sector of material use, Italy ranks in first position among European countries with a 42%, share of waste wood in panel production, followed by Austria with 33% (Silvio 2018). As resources, fossil and renewables are limited in their availability, though for different reasons, the European Green Deal laid the political basis for a shift from linear to circular economy. Products entering the cycle must be designed in a way that supports circular utilization (Fig. 1). However, repeated utilization of resources through recycling requires a thorough cleaning process to prevent contaminants that may have entered the resources cycle decades ago from being car- ried over and accumulated. As the use of natural resources gains massive interest, their efficient use together with con- sumer protection is of high concern. Many authors have therefore been working on the characteristics of different waste wood resources and their utilizations. Some focused on the origins and contaminants of waste wood materials (Tables 1, 2). The others concentrated on the application
2 Methods
The stated questions were addressed by collecting peer- reviewed articles, proceedings of conferences and reports of research projects relating to waste wood material and its utilization from the following scientific websites: • S c i e n c e D i r e c t (h t t p s : / / w w w. s c i e n c e d i r e c t . c o m /) • G o o g l e S ch o l a r (h t t p s : / / s ch o l a r. g o o g l e . c o m /) • Wo rl d C a t ( h t t p s : / / w w w. wo rl d c a t . o rg / ) • S p r i n ge r L i n k ( h t t p s : / / l i n k . s p r i n ge r. c o m /) • Taylor&Francis Online (https://www.tandfonline.com/) • AC S P u b l i c a t i o n s ( h t t p s : / / p u b s . a c s . o rg / ) • Web of Science (https://www.webofscience.com)
The following keywords were used:
• Waste wood contaminants • Waste wood composites • Recycled wood, formaldehyde emission
• Secondary wood resources • Wood residues utilization
Production
Product design phase
The term waste wood mentioned in the searched articles is restricted to used/secondary or recycled wood. Research articles, dealing with by-products from sawmills or the like are not included in this article. The collected publications for the review article were analyzed and categorized dealing with the research ques- tions focusing on the recycling of waste wood materials from wood-based panel products to produce wood-based panel only. Therefore, wood plastic composite-based publica- tions and the research papers that focused on waste wood materials from solid wood with and without CCA treated will not be discussed and shown up in the Supplementary information.
New resources entering
Existing resources cycle
Resources leaving
Energetic utilization/landfill/loss
End of product life
Fig. 1 Existing resources utilization pathways (solid line) and approaches towards a circular economy (dotted lines)
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