Trash, Heat, and Ash

This article highlights about process of incineration that offers French municipalities a number of advantages. First, it reduces the volume of solid waste to a fraction of its bulk. A metric ton of household waste leaves about 250 kg of bottom ashes and 30 to 50 kg of fly ash. This is an important consideration in France, which has much less landfill space than New World giants such as the United States or Canada. Combustion also sanitizes by destroying any microbes present, and the heat produced by the waste furnace can generate steam or hot water to heat residences, supply factories, or generate electricity in a turbine. Two popular French waste incinerator designs are rolling hearth and inclined grate furnaces. The former type contains a sloping series of rollers turned continuously by motor. As fuel slides down the rollers from top to bottom, solid residues drop out. Electricite de France is researching several ways of reducing the costs of vitrification. In laboratories near Fontainebleau, fly ash is fed into an electric arc furnace equipped with a graphite electrode.