Effect of accelerated carbonation on the chemical properties and leaching behaviour of Australian coal fly ash, to improve its use as a compost amendment

Abstract

Direct agricultural use of most Australian coal fly ashes is limited by their (1) extreme alkalinity, (2) extreme salinity and (3) trace metal leachability. Therefore, in order to use fly ash as a fertiliser source, the bio-availability of its nutrients needs to be improved by reducing its toxic elements and salinity. Application of fly ash as an amendment to carbonaceous compost has the potential to dilute the toxic effects of fly ash while enhancing the release of more nutrients to the soil through the chemical reaction between compost and fly ash. However, the elevation of pH and salinity levels in compost by the addition of fly ash may reduce the availability of some indigenous micro-org..