Research

4D-EARTH

Industrial spill in Hungary

A satellite view of the Hungarian sludge spill

Harald van der Werff, Freek van der Meer, Frank van Ruitenbeek, Wim Bakker and Chris Hecker
Dept. of Earth Systems Analysis, University of Twente

On the 4th of October 2010, a tailing reservoir collapsed in the Ajkai Timföldgyár alumina plant in Ajka, western Hungary. About a million cubic metres of liquid waste drained through the broken northwestern corner of the dam.  The mud formed a 1–2 m wave that covered about 40 square kilometres of land.  The village Kolontár and the town of Devecser were flooded, killing 8 and leaving several people missing, while dozens of residents were injured and needed to be hospitalized for chemical burns. The ruptured and weakened wall of the reservoir is momentarily in danger of collapsing entirely, which could release an additional 500,000 cubic metres of sludge. Despite counter measures of the Hungarian authorities, the spill reached the Danube river on 7 October 2010.

The mud is a waste product of purifying the mineral bauxite into alumina. The characteristic red colour comes from hydrated iron oxide, which is the main component of the mud. According to a press release by MAL Hungarian Aluminium, the mud had the following chemical percentage:

Metal oxide Percentage Notes
Fe2O3 (iron(III) oxide) 40–45 % Gives the red colour of the mud
Al2O3 (aluminium oxide) 10–15 % Unextracted aluminium oxide
SiO2 (silicon dioxide) 10–15 % Present as sodium- or calcium-alumino-silicate
CaO (calcium oxide) 6–10 %
TiO2 (titanium dioxide) 4–5 %
Na2O (bound sodium oxide) 5–6 % Responsible for the high pH and chemical burns

The red mud does not contain very high levels of heavy metals, although still about seven times the levels in normal soil.

Before

After

Two satellite images show the situation before and after the accident. The top image was acquired before the accident by the Advanced Visible and Near Infrared Radiometer type 2 (AVNIR-2) instrument on board of the Advanced Land Observing Satellite (ALOS). The lower image was acquired on October 10, 6 days after the accident, by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on board of the Terra satellite. The tailing reservoirs of the plant appear in bright blue and orange tones on the right side of the images. The yellow tones in the lower image show the extend of the sludge downstream of the reservoirs, discernible for several kilometers to the west. Spectral analysis of optical imagery will help in the future to monitor cleaning activities and natural decay of the sludge.

Industrial spill in Hungary from ITC-Utwente on Vimeo.

Further reading

Reuters (2010, October 6). Hungary declares emergency after red sludge spill. ReliefWeb. Accessed October 12, 2010. http://www.reliefweb.int/rw/rwb.nsf/db900SID/VDUX-89XNEP