Aluminum in Drinking Water
Aluminium or Aluminum is widely used in water treatment as a coagulation aid.This is the coagulation part of the coagulation/flocculation process; flocculation follows coagulation. During the flocculation process the particles join together to form flocs; the larger the flocs, the faster they will settle within a clarifier.
Other chemical coagulants used are Ferric Chloride and Ferrous Sulfate. Alum works best in the pH range of natural waters, 5.0 – 7.5. Ferric Chloride works best at lower pH values, down to pH 4.5. Ferrous Sulfate works well in through a range of pH values, 4.5 to 9.5.
In South Africa there is no limitation to the amount of Aluminum that can be dosed to the water merely the guidelines. I have always found it interesting why the human population in Africa appears to be so resistant to toxic pollutants and therefore doesn’t share the protection of the limitations that the EPA offers with their Max Contamination Level system.
The excerpt below is taken from the SAWQG – 1996 – 2nd edition which is used as the “bible” of South Africa Drinking Water Safety . Have a look at the note after the dosing table . Aluminium is also used in water treatment processes,
which may result in increased concentrations of aluminium in the final water.
Prolonged exposure to aluminium has been implicated in chronic neurological disorders such as dialysis dementia and Alzheimer’s disease. It is, however, not clear whether the presence of aluminium causes such conditions or is an indicator of other factors. Therefore, the link between aluminium in water and adverse effects on human health remains to be conclusively identified.
| Aluminium Range | Effects |
| Target Water Quality Range 0 to 0.15 | No acute or chronic health effects occur. Intake from water is < 5 % of the total dietary intake of aluminium. 0 – 0.15 Generally, no adverse aesthetic effects occur. Very slight discolouration of water may become apparent when iron or manganese is present in association with aluminiumat the upper limit of the range |
| 0.15 – 0.5 | Intake from water may exceed 5 % of the total dietary intake, but no effects on health are expected. Noticeable adverse aesthetic effects (colour) occur when aluminium is present in association with iron or manganese |
| > 0.5 | Intake from water exceeds 5 % of the total daily intake, but no acute health effects are expected except at very high concentrations. There may be long-term neurotoxic effects. This relationship has not been conclusively demonstrated. Severe aesthetic effects (discolouration) occur in the presence of iron or manganese |