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The Lime‐Soda Ash Method of Softening
Publication year - 1985
Publication title -
opflow
Language(s) - English
Resource type - Journals
eISSN - 1551-8701
pISSN - 0149-8029
DOI - 10.1002/j.1551-8701.1985.tb00374.x
Subject(s) - lime , water softening , softening , sedimentation , flocculation , hard water , magnesium , materials science , filtration (mathematics) , metallurgy , fly ash , mineralogy , soda lime , pulp and paper industry , chemistry , environmental science , environmental engineering , composite material , geology , mathematics , engineering , paleontology , statistics , organic chemistry , sediment
Lime‐soda ash softening is used in most larger treatment plants to remove dissolved minerals, especially calcium and magnesium, which cause hardness in water. When lime and soda‐ash are added, the hardness‐causing minerals form nearly insoluble precipitates. These precipitates are removed by the conventional processes of coagulation/flocculation, sedimentation, and filtration. The following types of lime‐soda ash processes are discussed: conventional lime‐soda ash treatment; excess‐lime treatment; split treatment; and caustic soda treatment. This article is adapted from the AWWA publication, Introduction to Water Treatment, Module 5, Softening.