The paper “Advances in understanding environmental risks of red mud after the Ajka spill, Hungary” was just published in the Journal of Sustainable Metallurgy.
This paper reviews the over 45 scientific studies published in the last 5 years assessing the key risks and impacts associated with the largest single release of bauxite residue to the environment – the 2010 Ajka red mud spill.
The main environmental concerns were covered in these studies, which also evaluated the effectiveness of the remedial actions taken. The key immediate risks after the spill were associated with the highly caustic nature of the red mud slurry and fine particle size, which once dry, could generate fugitive dust. Studies on affected populations showed no major hazards identified beyond caustic exposure. The dust risks were considered equal or lesser to those provided by urban dusts.
The longer term environmental risks were related with the potential salinization of inundated soils and release and potential cycling of metals and metalloids (e.g. Al, As, Cr, Mo, V) in the soil-water environment. Of these, those that are soluble at high pH, inefficiently removed from solution by dilution and likely to be exchangeable at ambient pH are of chief concern (e.g. Mo and V).
However, extensive management efforts in the aftermath of the spill greatly limited these exposure risks through neutralisation and red mud recovery from affected land. Monitoring of affected soils, stream sediments, waters and aquatic biota (fungi, invertebrates and fish) have all shown a very rapid recovery towards pre-spill conditions.
The accident also prompted research that has also highlighted potential benefits of red mud use for critical raw material recovery (e.g. Ga, Co, V, rare earths), carbon sequestration, biofuel crop production and use as a soil ameliorant.