Nitrate removal from groundwater by Donnan dialysis involves the dynamics of a multi-component solution. Transport kinetics of nitrate, and the accompanying anions sulfate and bicarbonate were investigated with three synthetic groundwater solutions. The effects of the water quality and of the anion exchange membrane type (Selemion AMV, Neosepta AMX, and Fumasep FAB) were examined using a Donnan dialyzer. It was found that water quality had only negligible effect on nitrate and sulfate transport through the AMV membrane. This was indicated by similar concentration decays of these anions with time as well as by comparable mass transfer coefficients obtained in the three water qualities tested. Additionally, very close nitrate and sulfate removal rates were obtained with the AMV and AMX membranes. Bicarbonate transport was the least efficient compared to the nitrate and sulfate. It was strongly impacted by both the water quality and the membrane type. The bicarbonate transport increased with augmentation of its molar fraction relative to the total anions in the solution. Overall, the results points to the high potential of Donnan dialysis for treating contaminated nitrate groundwaters.
- Ion exchange membrane
- Transport kinetics