TL:DR – Red mud pollution is the toxic waste left behind after aluminium oxide is extracted from the bauxite or in aluminium production
Red mud pollution, is bauxite residue. It is a toxic byproduct left over when alumina (aluminium oxide) is extracted from its ore, bauxite, in order to produce aluminium metal in the energy-intensive electrolytic Bayer process. For every ton of alumina produced from bauxite, approximately 1 to 1.5 tons of red mud pollution are released, amounting to almost 200 million tons each year. Red mud pollution is also sometimes known as bauxite tailings, red sludge, or alumina refinery residues.
Red mud is a highly alkaline waste product as well as containing toxic arsenic and mercury, which can cause serious harm if it enters the environment, having spilled from containment areas at bauxite works. This occurred in Ajka in Hungary in 2010 at an alumina plant, with devastating consequences.
Managing red mud pollution is a significant challenge given our reliance on aluminium across so many aspects of industry and the modern world. Scientists have worked on several methods to ameliorate its environmental impact by treating it with mineral acids, coating it with coal dust, or mixing it with silicate materials to reduce its harmful effects. Some of the above was adapted from Stanford University.
The Ajka red mud pollution incident was a major environmental disaster. A containment pond that was holding millions of cubic meters of red mud burst open and released the material into the surrounding towns. Ten people died and more than 100 were injured. The toxic sludge left homes uninhabitable and rendered farmland useless as well as damaging waterways. The cleanup took several years and cost billions of dollars.
The Ajka red mud pollution incident is yet another tragic reminder of the dangers associated with industrial waste and the importance of proper waste management and containment practices.
See also hexavalent chromium, commonly known as “chromium 6”.