Chemical and mineral composition of ashes from wood biomass combustion in domestic wood-fired furnaces

Abstract

The paper presents the results of studies on ashes produced from burning wood biomass in closed wood-fired furnaces, in individual household furnaces (Silesian Province, Poland). Dry sieve analysis and detailed granulometric analysis were performed with the Analysette 22 Micro Tec plus analyser. Content of the basic elements (Al, Si, P, Na, K, Mg, Ca, Fe) and potentially toxic elements (As, Pb, Cd, Zn, Cu, Ni, Cr, Hg) was determined by atomic absorption spectrometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS). Relative enrichment factors (REFs) were calculated for the elements (Pb, Cd, Zn, Cu, Ni, As, Hg, and Cr), and the emissions (E) of Pb, Cd, Hg, and As to the environment were estimated. The carbon content (40.2%–45.8%), H (3.7%–6.1%), O (46.2%–50.2%), N (0.12%–0.32%), and S (0.11%–0.96%) in wood biomass varies and depends on the wood species and drying period. The content of volatile parts in wood biomass ranges between 69.3 and 81%. Ash content varies between 2.6 and 18.3%. The wood calorific value ranges from 13.6 MJ/kg to 17.4 MJ/kg. Moisture content in the wood biomass ranges from 13.7% (briquette) to 46.7% (fresh birch). Identification of mineral composition and phases yields a high share of calcite, monetite, fairchildite, and quartz in the examined ashes. The combustion of wood biomass in fireplaces results in increased emissions of Pb and Cd to the atmosphere and may be the cause of introducing pollutants to waters and soils during ash storage.

Physico-thermal and emission properties of tissue cultured clone from Bambusa balcoaa (Beema bamboo) and Oxytenanthera abyssinica as sustainable solid biofuels

“…This is not desirable in solid biofuels. Birch wood and briquette were found to have ash contents of 18.3% and 10.7% respectively [ 39 ]. These ash content values were known to have great effect on the calorific value of the samples.…”

“…Consequently, high volatile matter is unwanted for solid biofuels and great efforts are made to reduce its content in the biofuel before utilization. Smołka-Danielowska et al [ 39 ] found that wood biomass is characterized by volatile matter content ranging between 69.3–81%. In a study on the production of solid biofuel from palm wastes, Yuliansyah et al [ 43 ] found that palm fronds and trunks had very high volatile matter of 82.5% and 83.9% respectively, which were not good for solid biofuels.…”

Leaching of heavy metals from wood biomass ash, before and after binding in cement composite

“…increase of fly ash content in mixtures, the concentration of heavy metals increases, which is in accordance with numerous authors' findings. 5,14,15 As, Ba, Cd and Pb appear in exchangeable fractions of both tested ash mixtures, which indicates direct leaching after disposal, and the higher the leaching the smaller ash particles are. 16 Pb was released the most from the Pd1 sample, in a concentration of 33.3 %, while 35.2 % of Pb was leached from the Pd2 sample.…”

“…Lower average concentrations of Pb, Cd, Hg and As are emitted by spruce combustion, compared to the combustion of wood briquettes from deciduous trees. 15 Due to the increased emission of these elements, there is a risk that occurs during combustion in open fireplaces in households.…”

Effect of tree species on the elemental composition of wood ashes and their fertilizer values on agricultural soils

“…Many studies on the elemental composition of wood ashes demonstrated wide variability in their contents due to different plant species, parts, and combustion temperatures (Huang et al, 1992; Semelová et al, 2008; Smołka‐Danielowska & Jabłońska, 2022). The contents of soil nutrients, for example, P, Ca, K, Cu, and Zn, are often reported in different wood ashes, providing a basis for the recent use of wood ashes in some agricultural fields (Semelová et al, 2008; Wierzbowska et al, 2020).…”