Removal of aluminium and iron from surface water by conventional water treatment

Abstract

Detailed source water monitoring showed large variations in the total concentrations of aluminium and iron in the Vaal Dam, South Africa, which were highlighted as a specific concern for one of the largest drinking water treatment plants in South Africa. This study aimed to better understand the presence of these metals in the source water, removal of these metals through the conventional treatment process, and final water quality trends, for the period 2008 to 2014. Aluminium and iron concentrations were highly variable and showed significant influence on colour and turbidity in source water. Sedimentation performed well, and removed over 70% of the metal concentration from the raw water. Filtration removed 15% of the remaining aluminium and iron concentrations. The pH and turbidity of the final water had minor effects on the metal concentration in the final water. The conventional treatment process was shown to be capable of removing aluminium and iron from the source water as both were within water quality limits in the final water. This study highlighted the importance of source water quality monitoring and treatment plant efficacy in evaluating whether the current treatment technology is appropriate for current and future challenges.