A new treatment method for acidic and aggressive water is presented. This method evades high pH-values and the difficulties in the prediction of the end-pH-values. Most of the kinetic problems of other treatment methods are not relevant here.
Difficulties in the prediction of end-pH-values are caused by the fact that phase transitions are not considered sufficiently. Even under evaluation of these transitions the predicted end-pH-values are not attained, because kinetic aspects are ignored.
Base addition and calcite treatment influence mainly the pH. Calcite saturation frequently appears at pH>9. Then, new solution of CO2 causes decreasing pH and new calcite aggression. Often, solution kinetics of calcite are too slow to establish saturation.
In most cases the new treatment method with mixed salts (the CarbonAdd principle) enables a predictable rise in both pH-value and buffer capacity. The saturation index of calcite is adjustable without negative affects on the saturation state of CO2. Thus, no new CO2 solution will influence the treated water. The result is a well buffered, stable water with an adjusted calcite saturation index and a pH-value around 8.
- buffer capacity
- dam water treatment
- drinking water treatment
- kinetic aspects
- pH adjustment
- © IWA Publishing 2002