Patent ID: 7771599

Claim:
A method for re-mineralizing process water in a seawater desalination plant, the method comprising the following steps: providing a reverse osmosis (RO) filter including an upstream inlet for seawater and a downstream outlet for RO permeate; providing a gas transfer membrane, the membrane including first and second counter current flow channels, each flow channel having upstream and downstream ends, seawater being supplied to the first flow channel and RO permeate being supplied to the second flow channel; adding sulfuric acid (H 2 SO 4 ) to the upstream end of the first flow channel to produce an acidified seawater solution, whereby the sulfuric acid (H 2 SO 4 ) reacts with bicarbonate (HCO 3 − ) present within the seawater to produce carbon dioxide (CO 2 ) gas in accordance with the following equation: H 2 SO 4 +HCO 3 − →CO 2 Eq. 1 passing the carbon dioxide (CO 2 ) gas through the gas transfer membrane, whereby the carbon dioxide (CO 2 ) gas is sequestered from the first to the second flow channel; adding calcium hydroxide (Ca(OH) 2 ) to the downstream end of the second flow channel, wherein the sequestered carbon dioxide (CO 2 ) dissolved in desalinated water reacts with the added calcium hydroxide (Ca(OH) 2 ) to produce calcium bicarbonate (Ca(HCO 3 ) 2 ) in accordance with the following equation: Ca(OH) 2 +2CO 2 →Ca(HCO 3 ) 2 the produced calcium bicarbonate (Ca(HCO 3 ) 2 ) being added to the RO permeate to thereby add hardness and alkalinity to the resulting water (H 2 O).