DETERMINATION OF WASTE COMPOSITIONS BY THE IDENTIFICATION OF FRACTION SPECIFIC MATERIAL SURFACES BY NEAR INFRARED-TECHNOLOGY AND THE ALLOCATION OF APPROPRIATE BASIS/SURFACE WEIGHTS

摘要

Currently, the composition of household waste and also substitute fuels are determined by manually conducted sorting analyses. However, these can only be randomly conducted, and the results are seldom representative due to the small quantity. With near-infrared technology it is possible to recognize the majority of the materials contained in wastes and substitute fuels and to detect their two-dimensional surfaces. With the help of comprehensive tests, it was initially possible to determine material-specific basis/surface weights. Because these two-dimensional surfaces are dependent on the state of condition (degree of reduction), basis/surface weights were detected for grain size classes < 40 mm, 40 – 80 mm und > 80 mm, and, accordingly, transfer factors between the grain size classes were calculated. The initial experiments to detect the mass-specific material composition of a mixture of waste materials failed because the particular waste/material fractions were often allocated to incorrect materials. Accordingly, it was determined for each waste/material fraction how strong the incorrect allocation to other materials takes place. With the help of misidentification rates and the development as well as the solution of a linear equation system, it was possible to correct/adjust the results, in order to compute a sufficient result in respect to the actual composition of waste and its corresponding low waste mass.