No matter whether waste is bio-mechanically pre-treated or burnt, it is advisable in any case to separate out any impurities. Venti Oelde offers a number of different air classifying systems, so-called wind sifters. These are characterized by using recirculating air and by their capability of handling large volumes. New developments such as the large particle separator complete the spectrum.

Even when bio-mechanical processing at a later date in waste processing plants is planned to produce secondary fuel, these classifiers are useful to generate a secondary fuel fraction with a high-calorific value