PAH removal from black sludge from aluminium industry by flotation using non-ionic surfactants

• Published in: Environmental technology Vol. 27; no. 9; pp. 1019 - 1030
• Main Authors: Dhenain, A, Mercier, G, Blais, J F, Bergeron, M
• Format: Journal Article
• Language: French; English
• Published: England 01.09.2006
• Subjects: Aluminum; Aluminum - chemistry; Flotation; Fluoride; Industrial Waste; Particulates; polycyclic aromatic hydrocarbons; Polycyclic Aromatic Hydrocarbons - chemistry; Q1; Sewage - chemistry; Soil; Surface-Active Agents - chemistry; Surfactants; Waste Management - methods
• ISSN: 0959-3330; 1479-487X
• DOI: 10.1080/09593332708618716

The valorization of black sludge is an environmental problem of the aluminium industry because of Polycyclic Aromatic Hydrocarbon (PAH), fluoride and alumina contents. A soil washing operated in a cell flotation with non-ionic surfactants (Brij 35, Igepal CA-720, Triton X-100, Tween 80) at different concentrations has been tested in order to remove the PAH (benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)fluoranthene, fluoranthene) detected in black sludge. The Tween 80 at 0.5% gave the best results with PAH removal rates between 35 and 50%. These percentages remain low due to the presence in large quantity of fine solid particles (45%) in the PAH concentrate produced by the flotation process. The substitution of the cell flotation by a column flotation allowed the reduction of this problem. Thus, the PAH removal rates reached 60%. This removal yield has been obtained with the lowest wash water flow-rate (150 ml min(-1)) and pulp total solids (10% p p(-1)) tested.