Environmental sustainability assessment of remediation alternatives for highly contaminated marine sediments

This study compares the environmental sustainability of five alternatives for the remediation of marine sediments of one of the most polluted coastal sites in Europe (Bagnoli-Coroglio bay, Mediterranean Sea), using the Life Cycle Assessment (LCA) methodology. The treatments are either in-situ or ex-situ, the latter requiring an initial dredging to transport the contaminated sediments to the management site. More in detail, four ex-situ remediation technologies based on landfilling, bioremediation, electrokinetic technique and soil washing were identified. These technologies are compared to an in-situ strategy currently under validation for enhancing bioremediation of the polluted sediments of the Bagnoli-Coroglio site. Our results indicate that the disposal in landfilling site is the worst option in most categories (e.g., 650 kg CO₂ eq./t of treated sediment, considering the nearest landfilling site), followed by the bioremediation, mainly due to the high energy demand. Electrokinetic remediation, soil washing, and innovative in-situ technology represent the most sustainable options. In particular, the new in-situ technology appears to be the least impacting in all categories (e.g., 54 kg CO₂ eq./t of treated sediment), although it is expected to require longer treatment time (estimated up to 12 months based on its potential efficiency). It can reduce the impact on climate change more than 12 times compared to the disposal and 7 times compared to bioremediation in addition to the possibility to avoid/reduce the dredging operations and the consequent dispersion of pollutants. The results open relevant perspectives towards more eco-sustainable and costly effective actions for the reclamation of contaminated marine sediments.