Recovery of Dilute Caustic Solution from the Desalination Plant Reverse Osmosis Discharge Brine Wastewater

Abstract

In the Gulf region, the major source of drinking water is from sea water desalination with reverse osmosis process. It is a well-known fact that during desalination process highly concentrated brine wastewater is being discharged into the deep sea. As a result, the sea water ecosystem and aquatic life are disturbed. The coral reefs are diminishing in the vicinity of brine wastewater discharge point. The aim of this project is to convert the desalination plant wastewater (brine) into dilute caustic solution. An electrodialysis unit was fabricated with silver anode and graphite cathode. A cation membrane and an anion membrane fixed to separate anode and cathode compartments. The wastewater samples were collected from the Sur, desalination plant. A study was conducted by varying direct current voltage of the electrodialysis unit from 24 V to 48 V. It was observed that at 24 volts the pH was steadily increased to 13.8 in 10 hours. The dilute caustic concentration was reached to 1.2% in 12 hours. The results are encouraging.