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5D + E - Risk communication + From risk mgnt to sust. mgnt? (MOP/191) Assessment and optimisation of a sediment treatment process based on a Life Cycle Assessment approach. Arevalo, Eduardo1, Stichnothe, Heinz1, Calmano, Wolfgang1, 1 Technical University Hamburg-Harburg, Hamburg, Germany, Germany ABSTRACT- Contaminated sediment management strategies must deal with significant economical, environmental and social constraints. The application of the principles of the Life Cycle Assessment (LCA) to evaluate and compare sediment management alternatives and remediation technologies can be regarded as a step towards a sustainable sediment management strategy. The Life-Cycle-oriented methodology applied allows the integration of economical and environmental objectives into the decision-making process. In this sense, this approach was applied exemplarily to assess and optimise a novel sediment treatment process at a pilot scale. Tributyltin (TBT) contaminated sediments were treated with the aim to decrease TBT concentrations to meet guideline values for relocation of sediments in the river avoiding the off-shore dumping at disposal sites. Due to the uncertainties and variability of results of models for potential impact quantification of toxic substances in LCA, an effect oriented approach based on a battery of bioassays to quantify sediment toxicity was incorporated into the methodology. The SED-TOX index approach (The SED-TOX index: Toxicity-directed management tool to assess and rank sediments based on their hazard. Bombardier et al., Env. Toxicol. and Chem., 18, 685-698, 1999) was used to integrate the results of the bioassays performed into a score that can be related to process operating conditions and incorporated into the assessment and optimisation methodology. The results indicate on the one hand that it was possible to decrease TBT concentrations to <0.1 mg/kg at current densities in the range of 50 to 75 A/m2. However, the SED-TOX score indicated an increase in the toxic effects of the sediment during treatment. A series of tests mixing these sediments with artificial river water simulating relocation effects showed that a decrease of toxicity to values lower than the initial levels is possible. Key words: sediment remediation, life cycle assessment, electrochemical treatment, tributyltin |
