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(097) Heavy metals lixiviation through a sandy soil amended with composted sewage sludge. Gasco, G.1, Alonso, J.1, Lobo, M.C.1, 1 ABSTRACT- The application of sewage sludges to agricultural soils is a practice that upgrades such urban residues as sources of organic matter and nutrients. Sewage sludges can be specially convenient to improve physical properties of degraded soils. Nevertheless, the presence of contaminants could constitute a potential pollutant source. Soil characteristics, sewage sludge origin and climatic conditions can affect the retention levels of the toxic constituents on the treated soils. Composted sewage sludges have a high content on heavy metals which could constitute a contamination source because of its potential lixiviation to ground waters. In this study, the mobility of some heavy metals (Cr and Zn) was evaluated in a greenhouse experiment. Two different composted sewage sludges were applied to a sandy soil in entral Spain. The study was carried out using olumns (1 m length, 11.4 cm diameter) through a reconstructed soil profile in a greenhouse. Composted sewage sludge were mixed with the first 10 cm for the dose of 220 tons/ha. Soil columns were irrigated during 3 months simulating twice annual region pluviometry. The heavy metals content were measured witha atomic absortion spectrometer with a graphite tube atomizer. The results showed that the leached metals were below the UE regulations limits; however the values obtained were according to the compost application and the type of the residue. Key words: soils, heavy metals, lixiviation, sewage sludge |
