Chemical Behaviour of Municipal Solid Waste Incinerator Bottom Ash in Monofills

Abstract

A method is presented to predict the short-term (months to years) and long-term (> 30 years) chemical behaviour of bottom ash from municipal solid waste incinerators in monofills. It is based on bottom ash composition and laboratory kinetic studies of bottom ash with water. Bottom ash after the quench tank is a reactive mixture in which slow and fast acid/base reactions occur. These intrinsic acid/base reactions continue for at least several months, and the end point is not yet known. The heavy metal concentrations observed in the aqueous extracts reflect primarily the advance of these reactions. Consequently leaching tests based solely on short-term (hours to months) extraction procedures cannot predict the chemical behaviour of bottom ash in monofills. However, laboratory experiments with samples of bottom ash, in which the intrinsic acid/base reactions have proceeded differently, provide useful information on the nature of chemical reactions significant in the short- and long-term.