Municipal Solid Waste Incineration Bottom Ash: Characterization and Kinetic Studies of Organic Matter

Bottom ash is the main solid residue (in weight) which is produced by municipal solid waste incineration (MSWI) facilities. To be reused in public works, it has to be stored previously a few months. This material is composed primarily of a mineral matrix but also contains unburnt organic matter. The mineral content and its change in the course of aging are relatively well-known, in contrast with the organic content. So in order to detect the phenomena responsible for changes in organic matter and their effects during aging, the concentrations of the main organic compounds previously characterized, the number of microorganisms, and the release of carbon dioxide were followed kinetically (over 13 months) in model laboratory conditions (mass, particle size, humidity, temperature, aerobiosis). The results showed that the aging process led to the natural biodegradation of the organic matter available in bottom ash, composed essentially of carboxylic acids and n-alkanes (steroids and PAH’s to a lesser extent), and consequently that it would improve the bottom ash quality. Furthermore these results were confirmed by the study of aging conducted in conditions used in the industrial scale (over 12 months).