An investigation of the potential application of bauxite residue in soil/sediment remediation

A series of laboratory experiments have been carried out using bauxite residue in order to investigate the possibility of its use: - in soil / sediment remediation - in soil / sediment stabilization. For this aim mixtures of bauxite residue with a variety of soil types were studied under various ratios. Carbonate soils of various CaCO3 content and various pH as well as silicate - rich soils / sediments were used. The investigation of the mixtures included pH measurement and their leaching with rain water and analysis for important elements. The above measurements were carried out: a) immediately after the mixing of the bauxite residue samples with the soil samples, b) three days after the mixing, c) thirty days after the mixing. Similar leaching experiments have been carried out using CH3COOONa. Other experiments included interaction of bauxite residue under various ratios with soils of low pH, contaminated soils adjacent to major roads and organic rich soils. Also, in other laboratory work the above experiments were carried out in the presence of gypsum and/or organic material. The results of this work are very encouraging. There are important indications suggesting that under certain conditions, after assessing the specific physicochemical conditions in the soils/sediments and examining all the limiting factors, bauxite residue can be used for soil/sediment remediation. However, for field operations further work is needed using the bauxite residue in plant and tree development. Our research is continued towards this direction.