Study of Variability of Waste Wood Samples Collected in a Panel Board Industry

Abstract

Waste wood is becoming an appealing alternative material to virgin wood, and the main drivers are the increased demand for waste wood by the panel industry, the introduction of renewable energy policies, and the waste framework directive. In fact, the use of waste wood as a secondary resource is favored over both landfills and combustion. The best reuse and cascading use of the material are linked to its characteristics. That is why it is important to know the chemical composition and the variation in the properties of such a heterogeneous material. In this article, a sampling study was carried out in a panel board company located in the northern part of Italy. In order to investigate the heterogeneity of waste wood, all samples have been analyzed by near-infrared spectroscopy. Nested analysis of variance and principal component analysis have been used to evaluate the heterogeneity and the variation in sample properties. The approach gives information about how to ensure representative measurements and efficiently describe the variability of the material. The results suggest that it is important to have replicates or at least two subsamples for each lot and then measure each of these with at least 100 scans, in order to get representative measurements and describe the variability of the material. The determination of waste wood composition and variability is the focal point for improving the sorting process and increasing the reuse of waste wood, avoiding expensive landfills and risks for human health and the environment.

Classification of Waste Wood Categories According to the Best Reuse Using Ft-Nir Spectroscopy and Chemometrics

“…In addition, this study demonstrates how class modelling approach can be used not only for authentication and detection purposes but also for sorting problems. In fact it is well known that waste wood presents a high inherent variability [20] and materials other than wood could be part of the waste wood material and need to be properly handled in the sorting facilities. For this reason, the classical discriminant approach cannot be applied for this purpose, since a non-wood sample would be incorrectly assigned to one of the three classes considered in this study.…”

“…We are well aware that this is far from how a classification could be implemented in the industry, as the whole sampling procedure in itself is an important issue. We have, though, earlier published a study focusing on this important aspect [20], and will therefore not go into that aspect in the current work.…”

“…In addition, traditional lab analysis requires a sampling of the waste wood material directly along the sorting process or in the waste wood pile and a subsequent transfer of the sample to the lab. Only a few grams of material are used for the lab analysis compared to the tons of waste wood handled, leading to well-known problems of reliability of the results due to the huge variability in material composition [19,20]. As a consequence, a technique that is rapid, economic, simple, and that can classify directly in the process line is necessary.…”

Application of Near Infrared Spectroscopy for the Detection of Chemically Treated Pellets Unsuitable for Combustion

“…These values permitted us to define the applicative degree of the model. As stated by different authors [47][48][49], RER should be between 7 and 20 for quality screening, and above 20 for quality control applications, while RPD should be above 3 for screening use and above 5 for control applications. All the computations were performed in MATLAB (ver.…”

“…Classification also aims to support the detection of the illegal use of waste materials, which can be difficult to identify in densified and homogenous products such as pellets. This helps to reduce the negative environmental impacts caused by the combustion of unsuitable materials [48,49]. Identification of both the treated components and the origin is crucial to ensure continuous and direct control of commercialized pellets and guarantee compliance with the environmental and safety requirements set by the standards [50].…”