Predicting the source strength of recycling materials within the scope of a seepage water prognosis by means of standardized laboratory methods

Abstract

The protection against harmful changes that can derive from the application of waste materials onto or incorporated into the soil has to be assured. In order to be able to evaluate the potential environmental risk the Federal German Soil Protection Act (Federal Bulletin, 1998) demands a seepage water prognosis. Objective of the workings that led to this thesis was to find an applicable, valid and generally accepted laboratory method for the determination of the source strength. Four batch tests, DEV S4 test, soil saturation extract, NH4NO3 extract and pH-stat test (at pH 4, 5, 6, 7, 11) were performed with the sandy and fine fractions of sediment dredged from the port of Bremen-City, municipal waste incineration ash and demolition waste. Saturated column tests were run with the municipal waste incineration ash, the demolition waste and the sandy fraction of harbour sediments. The sandy fraction of the harbour sediments was also incorporated in an unsaturated column unit. Main elements, heavy metals including As, Mo and V, the anions Cl, NO3 and SO4, IC and DOC were measured in all samples taken. Additionally electrical conductivity, pH and EH value were determined. It is shown that the results of the saturated laboratory column tests were transferable to those of unsaturated field-scale lysimeters conducted with municipal waste incineration ash and demolition waste. The column test can be regarded as a practicable tool to assess the time-dependend release of inorganic compounds under natural conditions.