Processing Options Of Heavy Fractions From MBT Plants

Published 2012

Citation: Meirhofer M, Ragoßnig AM, Sommer M. Processing Options Of Heavy Fractions From MBT Plants, ISWA Annual Congress Florence 2012, 17th-19th of September 2012, Florence, Italy. (peer reviewed)

Abstract

Heavy fractions resulting from mechanical treatment stages of Mechanical Biological Treatment (MBT) plants are posing very specific demands with regard to further treatment/disposal as they contain a high portion of inert material as well as a high portion of high calorific components. Based on the current Austrian legal situation (landfill ordinance: max. Higher Calorific Value (HCV) for MBT-fractions to be landfilled = 6,600 kJ/kg DM) this waste stream cannot be landfilled but must be thermally treated. In economic terms it is desirable to separate high calorific from inert waste components in order to allow for a material specific routing taking advantage of the difference in the costs for the downstream treatment / disposal.
In this conference contribution results of extensive processing experiments with the heavy fraction from the mechanical stage of the MBT plant of Umweltdienst Burgenland in Oberpullendorf, Austria, are presented. Experiments have been conducted with three different sensor-based automatic sorting systems (NIR – Multiplexer, NIR – Spectral Imaging, X-Ray transmission) as well as two density based processing technologies (wet treatment with a jigger, dry treatment with a cross flow air separation device). In addition a rotary shredder, which allows selective crushing, followed by screening has been investigated.
The performance of the processing options have been evaluated by characterizing the resulting product streams by means of manual sorting in order to evaluate purity and yield achieved by the respective treatment options. In addition to that chemical and physical parameters relevant for further treatment / disposal steps for the resulting product streams have been analysed. The inert fraction has been evaluated regarding the landfilling on a mass waste landfill on one hand and on a C&D waste landfill on the other hand. The high calorific product stream has been evaluated with regard to its thermal utilization.
Complementing the technical evaluation of the processing options an economical assessment of the processing options looked at including the economical implications of the resulting changes in the routing of the waste streams has been conducted.