Effects of substrate induced respiration on the stability of bottom ash in landfill cover environment

Abstract

The municipal solid waste incineration bottom ash is being increasingly used to construct landfill covers in Sweden. In post-closure, owing to increased cover infiltration, the percolating water can add external organic matter to bottom ash. The addition and subsequent degradation of this external organic matter can affect metal mobility through complexation and change in redox conditions. However, the impacts of such external organic matter addition on bottom ash stability have not been fully evaluated yet. Therefore, the objective of this study was to evaluate the impact of external organic matter on bottom ash respiration and metal leaching. The samples of weathered bottom ash were mixed with oven dried and digested wastewater sludge (1%-5% by weight). The aerobic respiration activity (AT4), as well as the leaching of metals, was tested with the help of respiration and batch leaching tests. The respiration and heavy metal leaching increased linearly with the external organic matter addition. Based on the results, it was concluded that the external organic matter addition would negatively affect the quality of landfill cover drainage.

Residual organic matter and microbial respiration in bottom ash: Effects on metal leaching and eco-toxicity

“…This would lead to a reduction of pH and enhanced formation of secondary mineral phases and reduced leaching of metals. This conclusion about the effect of microbial respiration and the ROM on the weathered ash is line with Ilyas et al (2014), who showed that the addition of organic matter and increased respiration lead to increased leaching metals in landfill covers.…”