A seminar will be held on 14 December 2021 at 11am at the Observatoire Midi Pyrénées in Toulouse, presented by Stéphanie Jacquet (MIO-CEM) and Christophe Monnin (GET - Toulouse).
Since the 1960s, residues (red mud) from the extraction of aluminium from bauxites produced by the Gardanne plant (Bouches du Rhône) have been discharged into the Mediterranean in the Cassidaigne submarine canyon off Cassis. In January 2016, this sludge discharge was replaced by a clarified liquid effluent obtained by filtering the red sludge, with the solid part of the waste being stored on land. In 2019, a new process for neutralising the liquid effluent has improved compliance with environmental standards. Recent studies of the chemical composition of the clarified effluent and of the mineralogical composition of concretions and sediments taken from the discharge area are shedding light on the dispersion of contaminants in the environment.
The case of the Gardanne alumina plant illustrates the general problem of managing waste from the mining industry, amplified here by a highly urbanised geographical context and a very long history of industrial activity.