The process of treating construction waste consists of a screening machine, wind sifter, sink–float separation and water treatment. The screening machine serves to separate the fine particle fraction and thereby reduces the amount of sludge produced later in the process. The oversize is further separated according to density. First, foils are removed with the help of a wind sifter. These can then be burned for energy recovery. The heavy fraction is transferred from the wind sifter to the sink–float separation system, where it undergoes further density separation using the density of water.

The heavy stones and metal parts are discharged and can be further separated by magnets. The light pieces of wood and plastic are washed and can then be burned for energy recovery in a similar way to the foil fraction. For continuous operation of the sink–float separation system, a lamella separator is needed to treat the process water for recirculation. Here the sediments have time to settle down, without the need of a big settling basin, which would take up a lot of space.

Mixed construction waste cannot be disposed on landfill because of its organic components. Thermal disposal on the other hand is too expensive. That’s why it should first be separated according to density so that inert waste can be dumped and combustible material can be burned for energy recovery.