Denitrification of wastewater with electrodialysis
A manufacturer of electrical appliances uses sodium nitrate solution for an electrochemical etching process. The sodium nitrate created concentrations of nitrate in the wastewater that were too high discharging in the sewage system. Options for treatment were biological denitrification or electrodialysis. After comparing both solutions, the client realised the operational costs of electrodialysis were half those of biological denitrification. The investment costs were comparable.
The two-step electrodialysis process concentrated the sodium nitrate to approximately 200 g/l and created a diluted stream that contains less than 0.5 g/l. Both streams could be reused in the electrochemical etching process.
The electrodialysis installation is running since 2003.