To eliminate water hardness, sodium carbonate can be used alone or in combination with quicklime. In environments where the temperature ranges between 30 and 40 degrees Celsius, solutions with concentrations of up to 30% of sodium carbonate can be used. Typically, a solution with a concentration of 8% sodium carbonate is prepared if the ambient temperature ranges between 10 and 15 degrees Celsius.
The basic idea of this technique is the movement of water via an electric field produced by a pair of positive and negative electrodes placed within the reactor. When hydroxyl ions (OH-) are produced on the positive electrode, an alkaline medium is created, tipping the carbonate balance in favour of calcium carbonate production and precipitation. When carbonic acids interact with hydrogen ions (H+) produced by the negative electrode, carbon dioxide gas is created, this gas goes up and is released or transformed as it moves through the reactor. The reactor's bottom is where the generated sediment accumulates and is continually eliminated. A device of this kind uses 0.5 to 1.5 kilowatt-hours of electric power per cubic metre of treated water.
A tub faucet with built-up calcification from hard water in Southern Arizona.
A barium chloride solution may easily remove sulphate ions from water. The sedimentation process is described by the following two equations:
