Amorim, Catarina L.Maia, Alexandra S.Mesquita, Raquel B. R.Rangel, António O.S.S.Loosdrecht, Mark C.M. vanTiritan, Maria ElizabethCastro, Paula M.L.2014-05-082014-05-082014AMORIM, Catarina L... [et al.] - Performance of aerobic granular sludge in a sequencing batch bioreactor exposed to ofloxacin, norfloxacin and ciprofloxacin. Water Research. ISSN 0043-1354. Vol. 50, n.º1 (2014), p. 101-113http://hdl.handle.net/10400.14/14328A granular sludge sequencing batch reactor (SBR) was operated for 340 days for treating a synthetic wastewater containing fluoroquinolones (FQs), namely ofloxacin, norfloxacin and ciprofloxacin. The SBR was intermittently fed with FQs, at concentrations of 9 and 32 mM. No evidence of FQ biodegradation was observed but the pharmaceutical compounds adsorbed to the aerobic granular sludge, being gradually released into the medium in successive cycles after stopping the FQ feeding. Overall COD removal was not affected during the shock loadings. Activity of ammonia oxidizing bacteria and nitrite oxidizing bacteria did not seemto be inhibited by the presence of FQs (maximum of 0.03 and 0.01 mM for ammonium and nitrite in the effluent, respectively). However, during the FQs feeding, nitrate accumulation up to 1.7 mM was observed at the effluent suggesting that denitrificationwas inhibited. The activity of phosphate accumulating organismswas affected, as indicated by the decrease of P removal capacity during the aerobic phase. Exposure to the FQs also promoted disintegration of the granules leading to an increase of the effluent solid content, nevertheless the solid content at the bioreactor effluent returned to normal levelswithin ca. 1month after removing the FQs in the feed allowing recovery of the bedvolume. Denaturing gradient gel electrophoresis revealed a dynamic bacterial community with gradual changes due to FQs exposure. Bacterial isolates retrieved from the granules predominantly belonged to a- and g-branch of the Proteobacteria phylum.engAerobic granular sludgeFluoroquinolonesNutrients removalMicrobial communityjournal article10.1016/j.watres.2013.10.043WOS:000330909600011