Water Treatment "Part 29": Additional methods for water softening.

1- Water softening with sodium carbonate (Na2CO3):

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.

2- The electrolysis process for water softening:

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.

3- Sulphates removal using barium chloride:

A barium chloride solution may easily remove sulphate ions from water. The sedimentation process is described by the following two equations:

CaSO4 + BaCl2 ===== CaCl2 + BaSO4

Na2SO4 + BaCl2 ===== 2NaCl + BaSO4

References:

• [Introduction to Water Chemistry (Pollution- Treatment- Analysis). Dr. Nasser Al-Hayek. Publication of the Higher Institute for Applied Sciences and Technology (HIAST). Syrian Arab Republic, 2017.]
• Taparhudee, Wara (2002). "Applications of Paddle Wheel Aerators and Diffused-Air System in Closed Cycle Shrimp Farm System" (PDF). Witthayasan Kasetsart (Sakha Witthayasat). 36: 408–419. Retrieved 26 April 2020.
• Unsafe water kills more people than war, Ban says on World Day". UN News. 22 March 2010. Retrieved 10 May 2018
• Raymond Desjardins- Livre: Le traitement des eaux- 2éme edition- Ecole Polytechnique de Montréal- 1997- ISBN 2-553-00643-8
• Drinking Water Treatment- EDX- Delft University of Technology.
• Book- Drinking Water: Principles and Practices- by Hans J C Van Dijk (Author), Jasper Q J C Verberk (Author), Peter J De Moel.