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Short-term Shutdown of Biological Activated Carbon Filters : Impacts on Water Quality

par Niquette, P.;Prévost, Martine;Servais, Pierre ;Beaudet, J.-F.;Coallier, J.;Lafrance, P.
Référence Journal - American Water Works Association, 90, 12, page (53-61)
Publication Publié, 1998

Article révisé par les pairs

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Résumé :

Biological activated carbon (BAC) filtration is used in drinking water treatment to biodegrade dissolved organic carbon (DOC) and to nitrify ammonia. This study evaluated BAC filters before, during, and after shutdown. Concentrations of five substrates were measured: ammonia, nitrite, nitrate, DOC, and dissolved oxygen. Media samples were taken simultaneously at similar depths to evaluate the effect of a shutdown on the densities of fixed bacteria. Dissolved oxygen concentrations quickly dropped below 2 mg/L within the BAC filters during the first 2 h of filter shutdown. At the same time, nitrite and bromide concentrations increased rapidly. Fixed bacterial biomass densities, measured at severa! depths in the filter after a 24-h shutdown, declined. Concentrations of DOC and ammonia, measured in the effluent after the filter was restarted, were higher than those measured before shutdown. Backwashing after shutdown, before the filter was returned to normal operation, eliminated these negative effects and restored the biodegradation performance of the BAC filters.