| Abstract: | Comparison of Selected Elution Procedures for the Valuation of the Mobility of Metals from Sediment and Sewage Sludge Several methods of extraction are generally used to evaluate environmental or ecological toxicity and deposition of waste material. In this paper, the application of the German standard methods DIN 38414-S7, DIN 38414-S4, pHstat method, “Schweizer method” (elution test, Switzerland), and some variants of the pHstat method on two very different samples are described. A rudimental sediment and a municipal sewage sludge are chosen as sample materials. The metal contents of extract solutions are determined by ICP-OES. The results of the DIN-S4 extractions depend definitely on the mechanic way of movement, i.e. the amount of heavy metals which are mobilized out of the samples differs considerably. In fact, DIN-S7 in combination with DIN-S4 is not sufficient to estimate the mobility of heavy metals. Solid samples should only be evaluated by applying a combination of several methods of extraction. The usefulness of the pHstat method for an evaluation is discussed. |
