Recent evidence indicates the widespread occurrence of numerous pharmaceutically-active
compounds (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 for
removing PhACs and other trace organic chemicals because these systems employ both sorption
and biodegradation simultaneously and are relatively simple to install and operate. Thus, the study
investigated the kinetics and equilibrium of the sorption of selected antibiotics (erythromycin,
ERY; sulfamethoxazole, SMX; and ciprofloxacin, CIP) to biofilm as a first step in characterizing
the fate of antibiotics in SRBF systems. Sorption experiments were conducted using a continuous
feed rotating annular bioreactor (CFRAB) system and the antibiotics were fed singly or together
as a cocktail at environmentally-relevant concentrations of 0.33 and 3.33 µg/L. Sorption rate
constant (k) values ranged from 0.048 to 4.465 h-1 with the trend as follows: (SMX >ERY>CIP).
The biofilm organic carbon sorption constant (Koc) ranged from 4,140 to 200,000 L/kg. The
relative order of Koc (CIP>>ERY>SMX) mimics what has been found for sorption to other
organic sorbents (typically expressed as Koc), but does not agree with the trend in reported logK<sub>ow</sub>
values (ERY>SMX>CIP). This suggests that octanol may not be a good model for biofilm with
respect to sorption of antibiotics. In the presence of dissolved natural organic matter (NOM), both the rate and extent of
antibiotic sorption to biofilm decreased. Results from this work are valuable for modeling
antibiotic fate in SRBF processes and other natural and engineered biofilm-mediated systems. Includes 41 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.1 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 14 |
| Published : | 11/01/2008 |
