Approaches for the treatment of waste streams of the aluminium anodising industry

The aluminium anodising industry is an important industrial sector that invariably generates great amounts of different waste streams. Classical and especially new-developing technologies dealing with them are reviewed. Innovative methods are mainly based on engineering geochemical processes, looking for the recovery of resource materials and the reduction of emissions to the environment. These represent a promising alternative to the classical method (neutralisation process and anodising mud disposal) which is an end-of-pipe solution. Among the treatments recently proposed, there are the use of anodising mud in the manufacture of refractory bodies, and the synthesis of useful minerals from the wastewaters arising from the etching, anodising and brightening processes. The viability of the application of such methods in the treatment of waste streams of the aluminium anodising industry is discussed, pointing out the main shortcomings and benefits of each of them. For those methods appearing environmentally friendly the process cost and the actual marketability of the final products should be determinant on their near future applicability.