Aluminium, its use and control, in potable water

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Abstract
The paper addresses the presence and use of aluminium in potable water and the need to control final residual levels. As a consequence of the ubiquitous nature of aluminium it is invariably present in many raw waters abstracted for potable use. Therefore even without the necessary use of aluminium flocculants there is a potential for residuals to be present in the water delivered to the consumer. It is generally accepted that the addition of aluminium flocculants is an essential step in the treatment of most raw waters for potable purposes. There are several aluminium flocculants that are used in the treatment of raw water throughout Europe. At working pH values precipitation occurs of highly insoluble chemicals, mainly aluminium hydroxide which is removed during the treatment process. However, some low residual level of soluble aluminium remains in the treated water. The paper considers these different aluminium flocculants ranging from monomeric aluminium sulphate to complex polymeric species and highlights that flocculation can be controlled to minimise these levels to meet current or future legislation. Over the past few years the presence of these residual aluminium levels on the potential health implications has caused considerable concern both in the industry and community at large and the paper attempts to put this into perspective.