Chemical and biological recovery of soils contaminated with antimony using eco-friendly materials

Antimony (Sb), a non-essential plant element, can be present in soils and waters in very high concentrations often due to a variety of anthropogenic activities. Though antimony is classified as a pollutant of priority interest, very little is known about its environmental behaviour and soil speciation.In recent years, different sorbents for the in-situ remediation of metalloid-polluted soils were proposed and tested with variable success. In a search for alternative, low-cost and environmental friendly Sb sorbents, drinking water treatment residuals (WTRs), the waste material resulting from the treatment of surface or ground water, and municipal solid waste compost (MSWC) were identified as potential good candidates.In this PhD thesis we showed that the Sb mobility, and its impact on the microbial and biochemical features of two soils artificially contaminated, were highly influenced by selected soil properties such as pH and organic matter content. Both WTRs and MSWC were able to act as effective Sb(V)-immobilizing agents in aqueous solutions especially at acidic pH (i.e. 4.5). Moreover, when added to a contaminated mine soil, the combination of both sorbents significantly reduced the mobility of antimony, alleviated its impact on soil microbiota and promoted a recovery of soil biochemical functioning. Plant growth (Helichrysum italicum L.) in the amended soil was finally enhanced while the Sb uptake was definitively reduced.