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Recent evidence indicates the widespread occurrence of numerous pharmaceutically-activecompounds (PhACs), including antibiotics, in surface waters world-wide. Slow-rate biofiltration(SRBF) systems, such as slow sand filtration and riverbank filtration, are a promising option forremoving PhACs and other trace organic chemicals because these systems employ both sorptionand biodegradation simultaneously and are relatively simple to install and operate. Thus, the studyinvestigated the kinetics and equilibrium of the sorption of selected antibiotics (erythromycin,ERY; sulfamethoxazole, SMX; and ciprofloxacin, CIP) to biofilm as a first step in characterizingthe fate of antibiotics in SRBF systems. Sorption experiments were conducted using a continuousfeed rotating annular bioreactor (CFRAB) system and the antibiotics were fed singly or togetheras a cocktail at environmentally-relevant concentrations of 0.33 and 3.33 g/L. Sorption rateconstant (k) values ranged from 0.048 to 4.465 h-1 with the trend as follows: (SMX ERYCIP).The biofilm organic carbon sorption constant (Koc) ranged from 4,140 to 200,000 L/kg. Therelative order of Koc (CIPERYSMX) mimics what has been found for sorption to otherorganic sorbents (typically expressed as Koc), but does not agree with the trend in reported logKsubow/subvalues (ERYSMXCIP). This suggests that octanol may not be a good model for biofilm withrespect to sorption of antibiotics. In the presence of dissolved natural organic matter (NOM), both the rate and extent ofantibiotic sorption to biofilm decreased. Results from this work are valuable for modelingantibiotic fate in SRBF processes and other natural and engineered biofilm-mediated systems. Includes 41 references, tables, figures.

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Edition: Vol. - No. Published: 11/01/2008 Number of Pages: 14File Size: 1 file , 1.1 MB