Remediation of PTEs Contaminated Soils by Washing Treatment with Biodegradable Reagents

This chapter discusses different aspects related to the soil washing techniques, in both ex-situ and in-situ configurations, and particularly focuses on the application and effectiveness of the remediation through biodegradable reagents. Nowadays, the use of these reagents is a key-factor to ensure a remediation process characterized by operating costs affordability and environmental sustainability. Low-molecular-weight organic acids (LMWOA), chelating agents, and biosurfactants can represent suitable extractant agents for the achievement of both high treatment efficiencies and minimized soil characteristics alteration. In this perspective, the characteristics of the main reagents involved in the washing process and the related mechanisms influencing the removal of Potentially Toxic Elements (PTEs) from soils are thoroughly analyzed. Indeed, the findings from previous studies highlight the need of preliminary investigations at lab scale to identify the soil properties and consequently select the best process operating conditions in order to perform feasible and effective treatments. Moreover, the literature review identifies the chelating agents as the most used extractants to date. Nonetheless, several researches aimed at further deepening this topic also indicate the LMWOA and biosurfactants as promising and less impacting alternatives in the near future also due to their possible low-cost production through biological processes.