Material Balance of a Construction Waste Sorting Plant

Abstract

The use and stock of construction materials has increased by two orders of magnitude over the past century. The composition of construction materials changes constantly, with the content of synthetic organic compounds and aluminium increasing since the 1940s. Today, construction wastes, which may experience a similar increase, are among the most abundant waste materials. A mass balance of a full scale construction waste sorting plant yielded the following results: the separation produced an organic fraction (25%), which is best treated in a municipal solid waste (MSW) incinerator, a metal fraction (3%) well suited for iron recycling, and two inorganic fractions (45 and 27% respectively) of a composition similar to the average earth crust. According to the composition and the reaction with water, leachates from landfills of construction wastes as well as of inorganic sorting fractions have to be treated for several decades. The chemical behaviour of the inorganic fractions is different from virgin construction materials. Thus, in order to reuse these fractions, specific additional experiments are needed. The potential of the mechanical sorting process to separate according to chemical properties appears to be limited. Nevertheless, the sorting fractions are better suited for landfilling and reuse than the initial construction waste.