Charakterisierung von Holzasche aus Biomassefernheizwerken

As a result of forcing the energy utilization from biomass, the amounts of combustion residues, especially woodash, are growing. For a sustainable and ecologically effective closed-cycle economy, the knowledge of the chemical composition of the ashes is necessary. The matrix wood ash is very complex, due to the great number of constituents in different concentrations. Therefore it is important to develop a combination of analytical methods for the complete detection of nutrients and heavy metals in wood ash. Ashes from different heating plants (wood chips-, bark-and sawdust combustion systems) were analysed with X-ray methods as well as with acid-digestion in combination with atomic spectrometry detection. The results were compared and checked for their plausibility by statistical methods and material balances for the inorganic elements from the biomass to the ash fractions. As a result of this evaluation astandard method is recommended for the analysis of wood ash. This method consists of a combination of dry (X-ray) analysis (for the elements Si, Ca, Mg, K, P, Al, Fe, Mn) and fluid analysis (for the detection of heavy metals).