Relevanz der Siebbedingungen bei der Bestimmung von AFS63 (feine abfiltrierbare Stoffe) in Verkehrsflächenabflüssen

Relevance of the sieving conditions during the determination of SS63 (Suspended Solids) in traffic area runoff

Abstract

Fine fractions of suspended solids (SS63) are a new decisive parameter for the qualitative assessment of stormwater pollution runoff in Germany. While total suspended solids (TSS) can be measured according to DIN 38409-2 or DIN EN 872, a standardized determination method for SS63 is still missing. Initial studies have shown that the sieving and dispersion conditions have a decisive influence on the result. In this article, systematically tests with different sieving methods (manual and instrumental, varying screen diameters and rinsing water volumes) as well as pre-dispersion types (vigorous shaking, ultrasonic, dissolver) on solids from traffic surfaces (road dust) with known particle size distribution are shown. Based on the laboratory tests, it was determined that the recovery of SS63 is successful with instrumental sieving. During manual sieving, a rinsing water volume adapted to the sieve surface must be ensured. For all sieving methods a pre-dispersion using vigorous shaking or dissolvers is recommended. Pre-dispersion with ultrasonic leads to the particles being broken up and thus to excess findings of SS63.