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Optimizing Direct Filtration in Brasília
Author(s) -
Bratby John R.
Publication year - 1986
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.1551-8833.1986.tb05785.x
Subject(s) - alum , filtration (mathematics) , effluent , filter (signal processing) , water treatment , raw water , ferric , pulp and paper industry , chloride , environmental engineering , slow sand filter , environmental science , mathematics , chemistry , engineering , statistics , inorganic chemistry , organic chemistry , electrical engineering
Results are presented of laboratory and pilot‐plant studies designed to define the optimum conditions for direct filtration at the Brasilia, Brazil, water treatment plant. The use of ferric chloride was found to offer definite advantages (longer filter runs and lower effluent turbidities) over the use of alum. For the raw waters studied, the use of cationic polyelectrolytes to reduce the metal coagulant dosage was not feasible. It was concluded that preflocculation prior to direct filtration was unnecessary and could even be detrimental to performance. With the coarse filter bed adopted, high backwash rates are required but with lower than normal total volumes of backwash water.