Assessment of chemical and material contamination in waste wood fuels – A case study ranging over nine years

Abstract

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.

Emissions of toxic pollutants from co-combustion of demolition and construction wood and household waste fuel blends

“…ST was selected as a reference wood material because of its low content of persistent organic pollutants (POPs), ash and metals. As was described in a previous study [15], DC is a material with elevated concentrations of chemical and material contaminants and, therefore, is very likely to produce pollutants when combusted. MSW is the household waste fraction remaining after the separate collection of household food waste.…”

“…The blend ratio 80:20 used when preparing the fuel blends meant that DC was the main source of chlorine in the blends. DC wood comprises considerable amounts of so-called material contaminants such as plastics, pieces of metal, glass or concrete [15].…”

“…DC-based fuels had, on average, 1590 mg/kg of Fe and 129 mg/kg of Cu; whilst ST-based fuels contained 511 mg/kg of Fe and 49 mg/kg of Cu ( Table 1). The copper in DC may come from copper-based preservatives such as CCA (chromated copper arsenate) [15,26,29,30]. Iron potentially originates from small metal scraps, but also from coating and paints [27].…”

Possible Interactions and Interferences of Copper, Chromium, and Arsenic during the Gasification of Contaminated Waste Wood

“…Waste wood (WW) is the term used for wood material that has previously been used for various purposes and is now being treated as a waste material; in the context of this study the waste wood is being utilized for energy production [1]. It comprises a wide variety of wood materials primarily from industrial and commercial activities and from construction and demolition operations [2,3].…”

“…It comprises a wide variety of wood materials primarily from industrial and commercial activities and from construction and demolition operations [2,3]. Since it is collected from diverse sources, WW may contain both physical and chemical contaminants [1,4]. Physical contaminates can simply be separated by sorting or using mechanical techniques.…”