Browsing by Author "Palma, Tânia Cristina da Luz"
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- An autochthonous aerobic bacterial community and its cultivable isolates capable of degrading fluoxetinePublication . Palma, Tânia Cristina da Luz; Shylova, Anastasiia; Carlier, Jorge; Costa, Maria ClaraBACKGROUND Fluoxetine is an antidepressant and recalcitrant fluorine pharmaceutical that is poorly biodegraded, so it enters the hydric resources and causes hazardous effects to aquatic environments. According to these fluoxetine features, the main aim of the present research was to find resistant bacteria in environmental samples with a high degradation efficiency. RESULTS The results obtained from raw municipal wastewater spiked with fluoxetine and inoculated with aerobic sludge from a Portuguese wastewater treatment plant under highly aerobic conditions showed that more than half and approximate to 89% of the drug was degraded after 48 and 144 h, respectively. During the assay, the initial population (mainly composed of Arcobacter, Bacteroides, and Macellibacteroides) shifted with an increase of members of the Acinetobacter, Rheinheimera, Shewanella, Pseudomonas, Methylobacillus, Piscinobacter genera and Aeromonadales order and the Pseudomonadaceae family, all of which were likely responsible for fluoxetine biodegradation. From the same sludge, six bacterial isolates were selected and identified as follows: Pseudomonas putida, Enterobacter ludwigii, Pseudomonas nitritireducens, Alcaligenes faecalis, Pseudomonas aeruginosa, and Pseudomonas nitroreducens; all of them grew with fluoxetine as sole carbon source. Pseudomonas nitroreducens showed the highest removal of 55 +/- 1% at 20 mg L-1 fluoxetine after 24 h. CONCLUSION An autochthonous aerobic bacterial community and its cultivable isolates showed the capacity to biodegrade fluoxetine. Biodegradation, rather than adsorption, appears to play the main role in the fluoxetine removal in aerobic conditions using bacteria simply obtained from an environmental sample. As far as is known, those bacteria are reported for the first time as fluoxetine biodegraders; thus, these bacteria are a promising option to integrate into new bioremediation processes aiming at the removal of fluoxetine.
- Degradation studies of widely used pharmaceutical compounds by heterogeneous photocatalysis and bacterial communities and isolatesPublication . Palma, Tânia Cristina da Luz; Costa, Maria ClaraThe present thesis was focused on degradation studies of five extensively and globally used pharmaceutical compounds: chloramphenicol, paracetamol, fluoxetine and 17α-ethynilestradiol which are considered emerging pollutants that enter in the environment due to its inefficient removal by the conventional wastewater treatments plants. Photodegradation and biodegradation assays were realized. The photodegradation of chloramphenicol and paracetamol was successfully performed by heterogeneous photocatalysis using PbS/TiO2 nanocomposites, as catalysts, which were synthesized using biological sulphide produced by sulphate reducing bacteria in batch cultures. Although photodegradation demonstrated to be a faster process, biodegradation is preferable since it occurs without the use of external compounds, such as catalysts, using only the microorganisms already present in the environment. Communities and bacterial isolates with ability to remove and use these drugs as unique carbon sources were obtained using sludge collected from an oxidation ditch and a lagoon system of WWTPs. An initial aerobic bacterial community suffered a shift to favor the genera Pseudomonas sp; Flavobacterium, Dokdonella and Methylophilus which displayed high efficiency in removing 50 mg/L paracetamol as sole carbon source and are described for the first time as paracetamol degraders. Bacteria capable of effectively biodegrade paracetamol were isolated in aerobic conditions, suggesting for the first time that members of “Bacillus cereus group”, [Brevibacterium] frigoritolerans, Corynebacterium nuruki and Enterococcus faecium can use paracetamol as carbon source, whereas the isolates obtained for fluoxetine and 17α-ethynilestradiol only partially removed these drugs. An anaerobic consortium which was able to degrade 20 mg/L of FLX, as unique carbon source, to values below the limit of detection was obtained. The final consortium was mainly composed by genera vadinBC27 wastewater-sludge group, Macellibacteroidetes, Dethiosulfovibrio, Bacteroides, Tolumonas, Sulfuricurvum, f_Enterobacteriaceae_OTU_18, which are for the first time assumed as FLX biodegraders. In the biodegradation of 20 mg/L FLX, a possible metabolite, 2,3-dimethyl-5-(trifluoromethyl) benzene-1,4-diol, was detected after 28 of assay. Several attempts to optimize an aerobic granular system were performed to degrade ibuprofen. This process is still ongoing.
- Photodegradation of chloramphenicol and paracetamol using PbS/TiO2 nanocomposites produced by green synthesisPublication . Palma, Tânia Cristina da Luz; Vieira, Bernardete; Nunes, J.; Lourenço, J. P.; Monteiro, O. C.; Costa, Maria ClaraThe present study describes the photocatalytic potential of the successfully synthesized nanocrystalline PbS/TiO2 nanocomposites in the photodegradation of chloramphenicol and paracetamol. PbS and PbS/TiO2 nanoparticles were synthesized using biological sulphide produced by sulphate-reducing bacteria in batch and in a coupled bioremediation system (upflow anaerobic packed-bed reactor) for acid mine drainage treatment, yielding near-complete metal precipitation (~ 100–99%, respectively). The PbS and PbS/TiO2 composites obtained using sulphide generated in batch have an average particle size ranging from 17 to 25 nm and 15 to 20 nm, respectively, while in bioreactor, both PbS and PbS/TiO2 particles have a similar size range from 20 to 50 nm. All the produced particles presented crystalline cubic structure. The specific surface area of TiO2 and PbS/TiO2 was estimated to be 46.559 m2/g and 38.005 m2/g, respectively. Chloramphenicol removal by photolysis was about 61% after 60 min of Hg irradiation and 36% under sunlight exposition. Chloramphenicol photodegradation using PbS/TiO2 as catalyst was successfully performed in a photoreactor (Hg medium pressure, 450 W) and under solar exposition with a high drug removal efficiency of 96% and 93% after 60 min and 240 min irradiation, respectively. Using TiO2 as a catalyst for photodegradation achieved 98% removal for both Hg and sunlight irradiation (UV index ranging 7–8) after 60 min and 240 min, respectively. Paracetamol removal by photolysis was about 18%. Drug’s photocatalytic degradation using PbS/TiO2 was successfully performed under sunlight exposition with a high removal efficiency of 93%, while in the presence of TiO2, the removal was complete, after 235 min irradiation.