META-ANALYSIS IN AEROBIC GRANULAR SLUDGE BIOREACTORS FOR WASTEWATER TREATMENT

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Fluoroquinolones biosorption onto microbial biomass: activated sludge and aerobic granular sludge

Publication . Ferreira, Vanessa R.A.; Amorim, Catarina L.; Cravo, Sara M.; Tiritan, M. E.; Castro, P. M. L.; Afonso, Carlos M. M.

Fluoroquinolones (FQs) have been reported in trace amounts in different environmental matrices. The biosorption of three most prescribed FQs, ofloxacin (OFL), norfloxacin (NOR) and ciprofloxacin (CPF) by activated sludge (AS) and aerobic granular sludge (AGS) was investigated. Biosorption assays were conducted with FQs concentrations within the range of 100e700 ng mL 1, to mimic environmental conditions. At neutral pH and at the end of 48 h, AS showed higher biosorption capacity than AGS. For AS, a maximum biosorption of 1.50 ± 0.03, 3.24 ± 0.05 and 3.39 ± 0.06 mg gTSS 1 was observed for OFL, NOR and CPF respectively, whereas for AGS the maximum amount of FQs biosorbed was 1.18 ± 0.03, 2.73 ± 0.02 and 2.94 ± 0.03 mg gTSS 1. Langmuir isotherm was more applicable for describing FQs biosorption equilibrium by AS while for AGS, the Freundlich isotherm was more adequate. Given the AGS technology innovative character, the effect of change of pH on the biosorbed FQs was evaluated. FQs could be desorbed from AGS at pH 3, pH 8 and pH 9 but at pH 4 the biosorption process was promoted. This study allows a better understanding of the FQs biosorption processes. Moreover, the data from biosorption/desorption from AGS may be useful for management and operation of AGS bioreactors

2016Journal article

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Treatment of a simulated wastewater amended with a chiral pharmaceuticals mixture by an aerobic granular sludge sequencing batch reactor

Publication . Amorim, Catarina L.; Moreira, Irina S.; Ribeiro, Ana T.; Santos, Lúcia H.M.L.M.; Delerue-Matos, Cristina; Tiritan, Maria Elizabeth; Castro, Paula M. L.

An aerobic granular sludge-sequencing batch reactor (AGS-SBR) was fed for 28-days with a simulated wastewater containing a mixture of chiral pharmaceuticals (CPs) (alprenolol, bisoprolol, metoprolol, propranolol, venlafaxine, salbutamol, fluoxetine and norfluoxetine), each at 1.3 μg L−1. AGS-SBR exhibited the highest removal efficiency for norfluoxetine, with preferential removal of the (R)-enantiomer indicating that biological-mediated processes occurred. For all other CPs, removal was non-enantioselective, occurring through biosorption onto AGS. A gradual decline of CPs removal was observed, probably related to the decrease of AGS adsorption capacity. Moreover, chemical oxygen demand (COD) content in the bulk liquid after anaerobic feeding increased, and P-release dropped, probably because the polyphosphate-accumulating organism's activity was affected. Nitrification was also affected as indicated by the ammonium effluent concentration increase. Moreover, CPs exposure promoted AGS disintegration, with decreasing granule size. After stopping CPs feeding, the AGS started to recover its compact structure, and the system returned its normal performance concerning COD- and P-removal. N-removal seemed to be a more sensitive process, as while the ammonium levels were fully restored at the end of operation, nitrite reduction was only partially restored. Results provide useful information on AGS performance during the treatment of wastewater containing pharmaceuticals, a frequent scenario in WWTP.

2016Journal article

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Enantiomeric fraction evaluation of pharmaceuticals in an aerobic granular sludge sequencing batch reactor

Publication . Amorim, Catarina L.; Moreira, Irina S.; Ribeiro, Ana R.; Santos, Lúcia H. M. L. M.; Delerue-Matos, Cristina; Tiritan, Maria E.; Castro, Paula M. L.

Pharmaceutical compounds are emerging environmental contaminants that have received growing attention over the last two decades. Several of these pharmaceuticals currently in use are chiral. Therefore, the evaluation of the enantiomeric fraction (EF) of chiral pharmaceuticals (CPs), during the removal processes occurring in the environment, is crucial for assessing the fate of such micropollutants. Aerobic granular sludge (AGS) technology is one of the promising biotechnologies in wastewater treatment. However, due to its technological novelty, up to now there is a lack of information regarding the fate of pharmaceuticals on such technology. In this study, the enantioselective removal of a mixture of eight CPs was monitored in a laboratory-scale AGS bioreactor. A synthetic wastewater supplied with racemic mixture (1.3 µg/L of each enantiomer) of alprenolol, bisoprolol, metoprolol, propranolol, fluoxetine, its metabolite norfluoxetine, venlafaxine and salbutamol was used to continuously feed the bioreactor during 28 days. Quantification of the CPs in influent and effluent samples was carried after pre-concentration and cleanup by solid phase extraction and analysis by liquid chromatography tandem mass spectrometry using an Astec ChirobioticTMV, 5 um (150 × 2.1 mm i.d). Enantioselective monitoring of the fate of CPs during exposure revealed that the pharmaceutical norfluoxetine at effluent exhibited EF values ranging from 0.44 to 0.74, indicating stereoselective processes occurring during the treatment, with preferential removal of the (R)-enantiomer. On the other hand, non-enantioselective removal was observed for all other CPs. Furthermore, high removal efficiencies (>96%) for both (R)- and (S)-enantiomers were achieved for norfluoxetine. For fluoxetine, relatively minor removal efficiency was observed, with approximately 85% of each enantiomer being removed from the total influent load. Total concentrations of all other CPs were reduced by about 47–61%. This study suggests that EF evaluation of CPs could be an effective mean of gaining insights into the overall treatment performance.

2015Conference object

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