Sustainability assessment of reactive capping alternatives for the remediation of contaminated marine sediments

The article deals with an original approach, based on sustainability, to select the best reactive capping alternatives for the remediation of contaminated sediments from Mar Piccolo (Italy), one of the most polluted marine ecosystems in Europe. Experimental tests were conducted to assess the capping effectiveness in contaminant sequestration and degradation. The environmental impacts were evaluated by using Life Cycle Assessment, while Multi Criteria Decision Analysis was implemented to consider the stakeholders’ view as well as to identify the best capping solution. The results indicated that the pollutants concentrations in the seawater increase in time without capping, involving possible risks to Mar Piccolo environment. Instead, after capping placement, environmental standards for seawater were always respected. Capping with Activated Carbon and Zero Valent Iron is the best solution for both chemical isolation (efficiency: 95%) and degradation aid (efficiency: 40%). Zero Valent Iron has higher environmental impacts, and it is closely followed by activated carbon and organoclay. The sustainability assessment shows how both the Reactive Permeable Mats with 3 kg/m2 Activated Carbon and Reactive Granular Materials with 5% Activated Carbon are the best solutions for Mar Piccolo remediation. The proposed methodology can be a step towards more sustainable decision making for contaminated sediments remediation.