Salt chlorination is a process for disinfecting swimming pool water, whether in water parks, campsites, hotels and resorts, or private pools. From salt water and through a process of electrolysis, hypochlorous acid is obtained naturally, without adding any chemical product, which is the main disinfectant agent that acts in the water.
To carry out disinfection by means of salt chlorination, first of all, common salt is added to the pool water. This initial step is carried out at a ratio of approximately 5 kg of salt per m³ of water (note that the salinity of seawater is around 30 to 35 kg per m³).
The salt water is then passed through an electrode, which carries out the electrolysis process. This will break down the salt water into various elements.
The reactions that will take place in the salt chlorinator (electrode) are as follows:
-A reduction reaction will take place at the cathode (or negative electrode), the by-products of which are molecular hydrogen and hydroxyl ions.
2·H2O + 2·e– → H2 + 2·OH–
-At the anode (or positive electrode), on the other hand, two oxidation reactions take place: one by water, in which molecular oxygen is produced.
2·H2O → O2 + 4·H+ + 4·e–
And another by salt, in which molecular chlorine is formed.
2·NaCl → Cl2 + 2·Na+ + 2·e–
After hydrolysis, hydroxyl ions and molecular chlorine combine to form hypochlorous acid:
Cl2 + OH– → HClO + Cl–
As we can see, salt chlorination thus provides the disinfectant product for the water in private swimming pools, or those in water parks, campsites and hotels and resorts. This disinfection is achieved by means of an alternative method to the classic addition of a chemical product such as sodium hypochlorite.
By Luis Llor, Senior Hydraulic Engineer in Amusement Logic’s Architecture Dept.
