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Chemical equilibria in split‐treatment softening of water
Author(s) -
Zipf Karl A.,
Luthy Richard G.
Publication year - 1981
Publication title -
journal ‐ american water works association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.466
H-Index - 74
eISSN - 1551-8833
pISSN - 0003-150X
DOI - 10.1002/j.1551-8833.1981.tb04718.x
Subject(s) - effluent , lime , softening , alkalinity , water softening , water treatment , process engineering , mathematics , environmental engineering , environmental science , chemistry , materials science , engineering , statistics , metallurgy , organic chemistry
Split‐treatment softening is more cost effective than conventional treatment with certain types of water. This paper develops the equilibria relationships for solving split‐treatment softening problems, in order to understand how desired effluent quality parameters and operating variables affect chemical requirements. Solution sets are presented for treatment with lime only and with lime and soda; effluent hardness and pH, effluent alkalinity and pH, or lime dose and bypass fraction are considered decision parameters. The methodology is applied to several raw water examples, and the results are presented graphically. Various modes of split‐treatment operation can effect a range of effluent quality characteristics. Minimal or optimal values are indicated for selection of process variables with respect to chemical costs.