Abstract
After the red mud spill in Hungary one of the risk reduction measures was to remove the deposits from the soil surface. The residual thin red mud layer was ploughed into the soil. The aim of the present 8-month-long lab-scale microcosm experiment was to estimate the red mud amount with no adverse effects on the soil as natural habitat and to assess the mid-term environmental risk of red mud mixed into the soil. The red mud ratio mixed into the soil ranged between 0–40 %. The experiments were monitored by physico-chemical, biological and ecotoxicological methods. Mixing of 5 % red mud into the soil significantly increased the total As, Cr, Ni, Pb and Na content of the soil, but it did not exceed the Hungarian soil quality criteria. The microcosms containing 5 % red mud did not show any adverse effects on the testorganisms. Overall, 5 % red mud could be mixed into the soil without any mid-term adverse effects.
Highlights
At present the global demand for aluminium metal is increasing because of its use for packaging and construction, from the fabrication of fuselages and car parts to disposable containers and various consumer durables [1]
4 Conclusion The effect of different red mud doses on the soil affected by the red mud disaster in 2010 at Ajka, Hungary was modelled in mid-term laboratory microcosm experiments
Mixing 5 w/w % red mud into sandy soil from the area affected by the spill has caused an increase in the total amount of As, Cr, Mo, Ni, Pb and Na, and in the water soluble fractions of Mo and Na
Summary
At present the global demand for aluminium metal is increasing because of its use for packaging and construction, from the fabrication of fuselages and car parts to disposable containers and various consumer durables [1]. Red mud is the slurry by-product generated from the treatment of bauxite with concentrated NaOH under elevated temperature and pressure by Bayer process [2]. It is highly alkaline with a pH usually ranging from 10 to 13 [3,4]. There were only two main red mud disposal methods: marine discharge and lagooning on land. The landbased disposal method traditionally adopted was one of wet disposal where red mud (15–30 % solids) is deposited on the land surface with additional construction of dams. The management of leachate water is necessary due to the high risk of seepage of alkaline solution to groundwater and it takes many years for the deposit to consolidate [6]
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