Title: Comparison of standard methods for evaluating the metal concentrations in bio ash

Authors: Janne Pesonen; Juhani Kaakinen; Ilkka Välimäki; Mirja Illikainen; Toivo Kuokkanen

Addresses: Faculty of Technology, Research Unit of Sustainable Chemisty, P.O. Box 3000, 90014, Oulu, Finland ' North Ostrobothnia Centre for Economic Development, Transport and the Environment, P.O. Box 86, FI-90101, Oulu, Finland ' Ahma Engineers Ltd, Kiilakiventie 1, FI-90250, Oulu, Finland ' Faculty of Technology, Fibre and Particle Engineering research group, University of Oulu, P.O. Box 4300, 90014 University of Oulu, Finland ' Faculty of Technology, Research Unit of Sustainable Chemisty, P.O. Box 3000, 90014, Oulu, Finland

Abstract: The current growth strategy and environmental legislation of the European Union both aim to increase the amount of renewable energy and to improve the use of waste streams. These policies mean there will be an increasing need to utilise bio ash. Currently, Finland and Denmark are the only European countries with specific national legislation concerning bio ash use. Sweden has recommendations concerning the use of bio ash fertilisers. Besides having different limit values for harmful elements and nutrients in ash fertilisers, all these countries have different digestion methods that are allowed for element content determinations. This study compared the results of the five digestion methods (aqua regia, nitric acid, nitric/hydrochloric acids, nitric/hydrochloric/hydrogen fluoride acids, and lithium tetraborate fusion) established by Nordic authorities. Two Finnish peat-wood fly ash samples were studied. Our results indicate that the choice of digestion methods produces a significant difference in the obtained heavy metal or nutrient concentration of bio ash, especially regarding the potassium concentration.

Keywords: bio ash; digestion method; environmental legislation; heavy metals; fertilisers; earth construction; metal concentration.

DOI: 10.1504/IJEWM.2017.087149

International Journal of Environment and Waste Management, 2017 Vol.20 No.3, pp.203 - 214

Accepted: 16 Mar 2017
Published online: 06 Oct 2017 *

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