CO2 footprint analysis of consolidated and innovative technologies in remediation activities

Effective remediation of contaminated soil requires selecting appropriate technology and adequate strategies. However, activities aimed at the remediation of contaminated sites or the treatment of effluents also have an environmental impact, since they make significant use of chemical products or processes. In the present work, the potential application of different remediation approaches to a real problem of heavy metal contamination was studied by examining the consequences of their environmental impact through a Life Cycle Assessment (CO footprint analysis) procedure, with the aim of identifying the least impacting option from an environmental point of view. Phytoremediation (with various options for the disposal of the biomass generated) and the electrokinetic approach (powered by renewable and non-renewable sources) were compared with soil washing (off-site, or ex-situ on-site) and excavation and landfill disposal (commercial or municipal waste). In all cases, the environmental impacts were reported in terms of global warming potential over a period of 100 years and normalized to the cubic meter of soil to be remediated. The analyses considered each process in its entireness (from cradle to grave) and an application on the whole area of the site to be reclaimed (an area of about 700 m located in an abandoned industrial district in Tuscany, Italy, and considered a "site of national interest"). The results obtained for each technology were then compared, highlighting those phases, activities and materials that present the greatest impacts for each approach (both in relative and absolute terms) and thus revealing aspects that would otherwise have been difficult to notice, such as the weight of chelating agents in phytoremediation or the use of energy from renewable sources for the electrokinetic approach. The resulting increase in knowledge on the technologies considered opens the way for further "eco-compatible" changes and improvements.