The increased demand for waste wood (WW) as fuel in Swedish co-combustion facilities during the last years has increased the import of this material. Each country has different laws governing the use of chemicals and therefore the composition of the fuel will likely change when combining WW from different origins. To cope with this, enhanced knowledge is needed on WW composition and the performance of pre-treatment techniques for reduction of its contaminants. In this study, the chemical and physical characteristics of 500 WW samples collected at a co-combustion facility in Sweden between 2004 and 2013 were investigated to determine the variation of contaminant content over time. Multivariate data analysis was used for the interpretation of the data. The concentrations of all the studied contaminants varied widely between sampling occasions, demonstrating the highly variable composition of WW fuels. The efficiency of sieving as a pre-treatment measure to reduce the levels of contaminants was not sufficient, revealing that sieving should be used in combination with other pre-treatment methods. The results from this case study provide knowledge on waste wood composition that may benefit its management. This knowledge can be applied for selection of the most suitable pre-treatments to obtain high quality sustainable WW fuels.

The influence of reactor type and operating conditions of the pyrolysis unit on the final concentration of toxic contaminants in biochar remains unclear. Therefore, we determined the concentrations of polycyclic aromatic hydrocarbons (PAHs), oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs), nitrogen-containing polycyclic aromatic compounds (N-PACs), polychlorinated dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) in biochars produced from three different feedstocks (softwood, wheat straw, and anaerobic digestate). Different scaled pyrolysis units (one batch and two continuous units) at two different temperatures (550 and 700 °C) were considered. The results revealed that the type of biomass had a significant influence on the PAH, oxy-PAH, and N-PAC content of the biochars. The configuration and type of the pyrolysis unit influenced only the wheat straw pyrolyzed at 550 °C. PCDDs and PCDFs occurred at very low levels in the biochars. In terms of PAH, PCDD, and PCDF content, the biochars assessed in this study represent a low risk to the environment, regardless of the temperature and type and size of the pyrolysis unit.

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A c c e p t e d M a n u s c r i p t 2 Car Fluff samples collected from a shredding plant in Italy were classified based on 20 particle size, and three different size fractions were obtained in this way. A comparison 21 between these size fractions and the original Light Fluff was made from two different 22 points of view: i) the properties of each size fraction as a fuel were evaluated; and ii) the 23 pollutants evolved when each size fraction was subjected to combustion were studied. 24The aim was to establish which size fraction would be the most suitable for the purposes 25 of energy recovery. The Light Fluff analyzed contained up to 50 wt.% fines (particle 26 size < 20 mm). However, its low calorific value and high emissions of polychlorinated 27 dioxins and furans (PCDD/Fs), generated during combustion, make the fines fraction 28 inappropriate for energy recovery, and therefore, landfilling would be the best option. 29The 50-100 mm fraction exhibited a high calorific value and low PCDD/F emissions 30were generated when the sample was combusted, making it the most suitable fraction 31 for use as refuse-derived fuel (RDF). Results obtained suggest that removing fines from 32 the original ASR sample would lead to a material product that is more suitable for use 33 as RDF. 34 35