Carbon Dioxide (CO2) in Water

Free (CO2) Carbon Dioxide in water exists in varying amounts naturally. Most well waters will contain less than 50 ppm of Carbon Dioxide in drinking water. A large amount of Carbon Dioxide in water creates an acidic water conditions. When carbon dioxide dissolves in water it creates the following; Water (H2O) plus carbon dioxide (CO2) yields carbonic acid (H2CO3). The dissociation of carbonic acid yields hydrogen (H+) and bicarbonate alkalinity (HCO3). The carbon dioxide in water ph value will drop as the concentration of carbon dioxide increases, and conversely will increase as the bicarbonate alkalinity content increases. Carbon dioxide in water equation is as follows; H2O + CO2 <====> H2CO3 <====> H+ + HCO3- Carbon dioxide in Water with a pH of 3.5 or below generally, contains mineral acids such as sulfuric or hydrochloric acid. Carbon Dioxide can exist in waters with pH values from 3.6 to 8.4, but will never be present in waters having a pH of 8.5 or above. The pH value is not a measurement of the amount of carbon dioxide in the water, but rather the relationship of carbon dioxide and bicarbonate alkalinity.

CO2- Carbon Dioxide Water Treatment - Free CO2 in water, can be easily dissipated by aeration. A two column deionizer (consisting of a hydrogen form strong acid cation and a hydroxide form strong base anion) will also remove the carbon dioxide from drinking water. The cation exchanger adds the hydrogen ion (H+) which shifts the above equation to the left in favor of water and carbon dioxide release. The anion resin removes the carbon dioxide by actually removing the bicarbonate ion. A forced draft degasifier placed between the cation and anion will serve to blow off the CO2 before it reaches the anion bed, thus reducing the capacity requirements for the anion resin. Another CO2 carbon dioxide water treatment option can be eliminated by raising the pH to 8.5 or above with a soda ash or caustic soda chemical feed system.