Assessment of two different separation techniques for building wastes

It is a well known fact that construction and demolition wastes (C and D wa stes) make up 50% of municipal wastes in countries with a high gross domest ic product (GDP). Besides questions about the handling of such enormous amo unts of waste, problems also occur with the chemical composition of the C a nd D wastes. The Latter problem is the result of the increasing use of synt hetic organic materials and heavy metals in construction engineering during the last decades. In this paper two different treatment technologies for C and D wastes are compared, a wet and a dry separation technique. The compa rison yielded the following results: both dry and wet technology are not ab le to select materials according to their chemical composition with the exc eption of iron, organic carbon and water soluble substances tin the case of wet sorting). Further, it is shown that there are only small differences i n the produced fractions of the two plants. Both plants produce a small gra in size fraction with the highest content of trace elements, which should b e removed Frier to reuse. It became obvious that the (chemical) quality of the input is the most important factor in view of the quality of the output fractions. Consequently, this makes separation of C and D wastes at source , a necessity on the way to multiple recycling steps.