Aluminium in drinking water: An overview

Aluminium (Al) is one of the trace inorganic metals present in drinking wat er. In addition to the naturally occurring Al in raw waters, use of Al-base d coagulants especially Al-2(SO4)(3) (alum) often leads to an increase in t reated water Al concentrations. A high (3.6 to 6 mg/l) concentration of Al may precipitate as aluminium hydroxide giving rise to consumer complaints. Al is also a suspected causative agent of neurological disorders such as Al zheimer's disease and presenile dementia. During conventional water treatme nt processes, Al undergoes various transformations (also called 'speciation ' of Al) which are influenced by factors such as pH, turbidity, temperature of water source, and the organic and inorganic ligands present in water. C hemical precipitation, reverse osmosis, electrodialysis and cation exchange methods are efficient in AI removal from water. This paper gives an overvi ew of the presence of Al in drinking water with reference to its speciation , removal (treatment methods), water supply and health problems, and the re gulation of its levels in drinking water.