Recycling of Biomass Ashes: Current Technologies and Future Research Needs

Brigitte Amalia Knapp and Heribert Insam

Abstract Biomass ash is a final by-product from biomass incineration and is being produced in increasing amounts. Ash contains a variety of macronutrients and micronutrients and thus requires an appropriate recycling strategy. This chapter addresses various recycling strategies and technologies, with a particular focus on a smart combination of wastes from different sources for optimising recycling efficiency.

1.1 Introduction

Biomass ash is the solid residue accumulating from the thermal combustion of plant biomass for heat and electricity production, containing a variety of macronutrients and micronutrients resistant to incineration. As combustion of biomass is among the dominant bioenergy applications worldwide, increasing numbers of biomass-based power plants are being built and thus vast quantities of ashes are produced. Despite the value of the various elements contained in the ashes, their disposal in landfills is still common practice, generating considerable costs for biomass plant operators and negating the recycling potential of ashes. A prerequisite for sustainable use of ashes in agriculture and forestry, however, is their quality in terms of heavy metal contents and organic pollutants. Appropriate combustion and separation techniques for the different ash fractions are thus highly needed.

To bring together knowledge and ideas on the reutilisation of biomass ashes, a conference entitled “Recycling of Biomass Ashes” was held in Innsbruck in March 2010, focusing on various recycling technologies for biomass ashes. The confer­ence sessions were targeted at the use of ashes as fertiliser or a supplement for organic and inorganic fertilisers as well as their combination with compost and anaerobic sludges. Further, ash amendments to forest soils were a major topic, as was the use of ashes for geotechnical constructions and industrial processes.

B. A. Knapp (H) and H. Insam

University of Innsbruck, Institute of Microbiology, TechnikerstraBe 25, 6020 Innsbruck, Austria e-mail: b. knapp@uibk. ac. at

H. Insam and B. A. Knapp (eds.), Recycling of Biomass Ashes,

DOI 10.1007/978-3-642-19354-5_1, © Springer-Verlag Berlin Heidelberg 2011

Moreover, national and international policies regulating the application of ash were presented and joint programmes for advancing knowledge in the field of ash recycling were discussed.

In the following chapters an overview of different fields of application for biomass ashes is presented, summarising current knowledge on the reutilisation of biomass ashes and highlighting future research needs. As most investigations on ash recycling are based on wood ash, this chapter will focus on ash produced from wood combustion.

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