Table of Contents

Waste to Energy (WtE) technology has been implemented in European and many Asia countries with tremendous success and social acceptance. Bottom Ash (BA) generated from this process has also been effectively used as raw material or by-product in many applications. This technology, however, is still in its infancy in Australia. Additionally, the market and appetite for enduse of BA is still to be explored. One such option for its enduse is in landfill capping as a capillary barrier to reduce water infiltration into buried waste. Bottom ash from WtE plants could be used as a capillary barrier in phytocaps – an alternative landfill capping techniques which uses tree and soil to reduce water infiltration into waste.
Literature suggests that with proper treatment (stabilisation) or proper mixing and adequate curing, the hydraulic conductivity of BA can be increased (Circa 10-7 cm/s) by increasing its density and significantly reducing the threshold limits of heavy metals and other contaminants that may otherwise pose a risk to the environment.

Keywords: landfill, bottom ash, capillary barrier, phytocapping, waste-to-energy