Water Hardness Removal for Industrial Use: Application of the Electrolysis Process

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Water Hardness Removal for Industrial Use: Application of the Electrolysis Process

Water Hardness Removal for Industrial Use: Application of the Electrolysis Process 

Agostinho, Nascimento and Cavalcanti 


Lime–soda softening for treating very hard waters is generally applied as a conventional water treatment process for municipal use. However, for industrial use, this treatment is not applied because: (a) it requires a long detention time for magnesium and calcium precipitation (about 4, 5 hours); (b) a supersaturation associated with an hexahydrate CaCO3 formation can be accomplished leading to severe incrustation of conduits and (c) a post-stabilization of final water is needed. This paper addresses a study on the performance of the electrolysis process applied “per se” and with alkaline chemical dosing for removal of noncarbonated hardness for industrial use. The water used in experiments was the tap water of the reticulation system of Campina Grande in Paraiba state, Brazil. Results showed that the production of primary coagulant during electrolysis improved flotation of both calcite (calcium carbonate, CaCO3) and magnesium hydroxide, Mg (OH)2. The overall removal rate obtained with this process was 80% with a detention time of 40 minutes which is about 17% of the time needed in conventional Water Treatment Plants. 

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