Ex-situ evaluation of bauxite residues as amendment for trace elements stabilization in dredged sediment from Mediterranean Sea: A case study

• Bauxite residues were investigated as mineral amendments for dredge marine sediment stabilization.
• Application of 5% bauxite residue to dredged sediment is a sustainable approach to limit leaching of cationic pollutants.
• Leachates toxicity towards rotifers (Brachionus plicatilis) was high after 48 h of contact.
• Improvements are needed to limit leaching of anionic pollutants and to lower toxicity of the leachates.

Stabilization of marine dredged sediments contaminated with multi-elements is a challenging task in choosing the appropriate sorbent and application dosage. The present study investigates the possibility of using bauxite residues (Bauxaline® and Bauxsol) as amendment for the treatment of contaminated sediment. A pilot scale experiment was conducted for three months to stabilize trace elements in composted contaminated sediment sample using 5% by-product amendment. The results showed that after 3 months of treatment, cationic trace elements were effectively immobilized but increased leaching of anionic pollutants was observed. Increased leaching of anionic pollutants could be limited by addition of higher quantities of amendments. The total content of available pollutants decreased in stabilized sediments but this treatment has no effect on the classification of waste. The leachates were then evaluated for acute toxicity using estuarine rotifers Brachionus plicatilis. Bauxite residues can be inexpensive choices for the stabilization of cationic pollutants in dredged sediments.