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(088) Chemical and ecotoxicological characterisation of leachates from new materials developed for civil engineering. Lapa, Nuno1, Mendes, Benilde1, Oliveira, José Filipe1, 1 ABSTRACT- Bottom ashes produced through the incineration of municipal solid wastes have been used in the European project Valomat, with the aim to develop new materials for civil engineering. The three main areas for their application were the filling of old quarries, underground constructions and embankment reinforcement. Materials with different physical characteristics were developed for each application. Three major scenarios of exposure, under real conditions, were considered: a) direct exposure to underground water; b) direct exposure to natural soil; c) direct exposure to natural climatic conditions. For each scenario, a pilot plant was constructed and seven samples of new materials were studied under laboratory conditions or natural weather. The assessment of leaching behaviour of new materials was performed through the evaluation of chemical composition and ecotoxicological properties of the leachates produced in each pilot. Twenty-one chemical parameters were determined in the leachates. The ecotoxicological characterisation comprised the use of the following assays: a) luminescence inhibition of bacteria Photobacterium phosphoreum; b) growth inhibition of freshwater algae Pseudokirchneriella subcapitata; c) mobility inhibition of crustacean Daphnia magna; d) germination inhibition of Lactuca sativa seeds. The results obtained within the eight months of work performed until now pointed out for a general decrease on the concentrations of metals, pH and conductivity values determined in the first 47 days of assay, for leachates of materials immersed in water and exposed to natural weather. P. phosphoreum have presented the highest sensitivity to measure the ecotoxicological level of leachates. The highest values of EC50 were obtained for leachates collected within 47 days of assay. The results obtained indicated a strong possibility of valorisation of such materials for civil engineering. Key words: chemical characterisation, ecotoxicological evaluation, leachates, new materials for civil engineering |
