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- Long-term stability of a non-adapted aerobic granular sludge process treating fish canning wastewater associated to EPS producers in the core microbiomePublication . Paulo, Ana M. S.; Amorim, Catarina L.; Costa, Joana; Mesquita, Daniela P.; Ferreira, Eugénio C.; Castro, Paula M. L.The tolerance of aerobic granular sludge (AGS) to variable wastewater composition is perceived as one of its greatest advantages compared to other aerobic processes. However, research studies select optimal operational conditions for evaluating AGS performance, such as the use of pre-adapted biomass and the control of wastewater composition. In this study, non-adapted granular sludge was used to treat fish canning wastewater presenting highly variable organic, nutrient and salt levels over a period of ca. 8 months. Despite salt levels up to 14 g NaCl L−1, the organic loading rate (OLR) was found to be the main factor driving AGS performance. Throughout the first months of operation, the OLR was generally lower than 1.2 kg COD m−3 day−1, resulting in stable nitrification and low COD and phosphorous levels at the outlet. An increase in OLR up to 2.3 kg COD m−3 day−1 disturbed nitrification and COD and phosphate removal, but a decrease to average values between 1 and 1.6 kg COD m−3 day−1 led to resuming of those processes. Most of the bacteria present in the AGS core microbiome were associated to extracellular polymeric substances (EPS) production, such as Thauera and Paracoccus, which increased during the higher OLR period. Ammonium-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) species were detected in AGS biomass; while AOB were identified throughout the operation, NOB were no further identified after the period of increased OLR. Different polyphosphate-accumulating organisms (PAOs) were detected along the process: Candidatus Accumulibacter, Tetrasphaera and Gemmatimonas. A non-adapted granular sludge was able to treat the fish canning wastewater and to tolerate salinity fluctuations up to 14 g L−1. Overall, a high microbial diversity associated to EPS producers allowed to preserve bacterial groups responsible for nutrients removal, contributing to the adaptation and long-term stability of the AGS system.
- Simultaneous partial nitrification and 2-fluorophenol biodegradation with aerobic granular biomass: reactor performance and microbial communitiesPublication . Ramos, Carlos; Amorim, Catarina L.; Mesquita, Daniela P.; Ferreira, Eugénio C.; Carrera, Julián; Castro, Paula M. L.An aerobic granular bioreactor was operated for over 4months, treating a synthetic wastewater with a high ammonium content (100mgNL-1). The inoculum was collected from a bioreactor performing simultaneous partial nitrification and aromatic compounds biodegradation. From day-56 onwards, 2-fluorophenol (2-FP) (12.4mgL-1) was added to the feeding wastewater and the system was bioaugmented with a 2-FP degrading bacteria (Rhodococcus sp. FP1). By the end of operation, complete 2-FP biodegradation and partial nitrification were simultaneously achieved. Aerobic granules remained stable over time. During the 2-FP loading, a shift in the community structure occurred, coinciding with the improvement of 2-FP degradation. DGGE analysis did not allow to infer on the bioaugmented strain presence but pyrosequencing analysis detected Rhodococcus genus by the end of operation. Together with other potential phenolic-degraders within granules, these microorganisms were probably responsible for 2-FP degradation.
- Development of a low pressure chromatographic flow system for monitoring the biodegradation of ofloxacin and ciprofloxacinPublication . Santos, Inês C.; Mesquita, Raquel B. R.; Amorim, Catarina L.; Castro, Paula M. L.; Rangel, António O. S. S.In this work, we propose a simple low pressure chromatography method with a high throughput for monitoring the biodegradation of fluoroquinolones. Fluoroquinolones are a class of antibiotics that have been accumulating in the environment as a consequence of their release from different sources, namely hospital waste. It has been found that wastewater treatment plants are not able to completely remove this type of micro-pollutants and so, alternative solutions are necessary. Some biodegradation studies have been done but the HPLC-based methodologies used to monitor the degradation process usually require high cost instrumentation such as analytical columns and detectors. For this reason, a 1 cm monolithic column was coupled to a flow injection system and used for the simultaneous quantification of ofloxacin and ciprofloxacin with UV detection at 295 and 275 nm, respectively. LODs of 0.5 and 0.29 mg L-1 for ofloxacin and ciprofloxacin were obtained, respectively, with repeatability within the range of 2–10%. The developed method was successfully applied to monitor the biodegradation of ofloxacin and ciprofloxacin by the strain Labrys portucalensis F11. The results proved that the low pressure chromatography method is a simpler, cheaper, and faster alternative to monitor biodegradation studies.
- Biological treatment of a contaminated gaseous emission from a leather industry in a suspended-growth bioreactorPublication . Carvalho, M. F.; Duque, A. F.; Moura, S. C.; Amorim, Catarina L.; Ferreira Jorge, R. M.; Castro, Paula M. L.A suspended-growth bioreactor (SGB) was operated for the treatment of a gaseous stream mimicking emissions generated at a leather industrial company. The main volatile organic compounds (VOCs) present in the gaseous stream consisted of 1-methoxy-2-propanol, 2,6-dimethyl-4-heptanone, 2-butoxyethanol, toluene and butylacetate. A microbial consortium able to degrade these VOCs was successfully enriched. A laboratory- scale SGB was established and operated for 210-d with an 8 h cycle period and with shutdowns at weekends. Along this period, the SGB was exposed to organic loads (OL) between 6.5 and 2.3 £ 102 g h¡1 m¡3. Most of the compounds were not detected at the outlet of the SGB. The highest total VOC removal efficiency (RE) (ca 99%) was observed when an OL of 1.6 £ 102 g h¡1 m¡3 was fed to the SGB. The maximum total VOC elimination capacity (1.8 £ 102 g h¡1 m¡3) was achieved when the OL applied to the SGB was 2.3 £ 102 g h¡1 m¡3. For all the operating conditions, the SGB showed high levels of degradation of toluene and butylacetate (RE t 100%). This study also revealed that recirculation of the gaseous effluent improved the performance of the SGB. Overall, the SGB was shown to be robust, showing high performance after night and weekend shutdown periods.
- Performance of microalgae-bacteria granular sludge for nutrient removal of freshwater aquaculture wastewaterPublication . Couto, Ana T.; Miranda, Catarina; Cardador, Martim; Amorim, Catarina L.; Castro, Paula M.L.
- Variability in the composition of extracellular polymeric substances from a full-scale aerobic granular sludge reactor treating urban wastewaterPublication . Oliveira, Ana S.; Amorim, Catarina L.; Ramos, Miguel A.; Mesquita, Daniela P.; Inocêncio, Paulo; Ferreira, Eugénio C.; Loosdrecht, Mark van; Castro, Paula M. L.Within the framework of the circular economy, there is a need for waste management alternatives that promote the reuse of materials produced in wastewater treatment plants (WWTP). An interesting option is the recovery of extracellular substances from sludge. The variability of characteristics of potential recovered bioproducts has to be assessed in full scale operational settings. In this study, aerobic granular sludge (AGS) from a full-scale WWTP treating urban wastewater was regularly collected for 4 months to assess variability in extracellular polymeric substances (EPS) composition and in granular morphology. Variations in the EPS composition occurred with time. Proteins and humic substances were the main EPS components (329–494 and 259−316 mg/g VSS of AGS, respectively), with polysaccharides and DNA representing minor components. The application of an extra purification step after extraction to obtain a purer EPS led to a decrease in the yield of each EPS component, particularly pronounced for the polysaccharides. The final product had a rather constant composition for the monthly samples. The granules showed morphological stability throughout the sampling period and the yield of EPS was correlated to the size of the granules, higher when there was a higher content of small granules (Deq<150 μm) comparing to intermediate (150 ≤ Deq<1500 μm) or large granules (Deq≥1500 μm). This is the first time that a potential valorization strategy for surplus AGS biomass is studied in a full-scale environment. Knowledge on yield and product homogeneity is important as these features are essential for downstream application of the recovered EPS.
- Intermittent load of 2-fluorophenol in saline wastewater shapes aerobic granular sludge microbiome and reactor performancePublication . Oliveira, Ana S.; Amorim, Catarina L.; Loosdrecht, Mark C. M. van; Castro, PaulaIndustrial effluents often contain organic pollutants and variable salinity levels, making their treatment challenging. Aerobic granular sludge (AGS) is an innovative and compact wastewater treatment technology for the treatment of domestic and industrial water streams. The high content of extracellular polymeric substances (EPS) in AGS composition is thought to protect , to some extent, the microbial communities from stressful conditions in external environment. This work aimed to evaluate the robustness of AGS systems in terms of nutrient removal performance and to unravel the protective role of EPS towards transient feeding with a toxic pollutant (2-fluorophenol - 2-FP) in saline wastewater. Moreover, the taxonomic and functional patterns of the AGS microbiome were characterized and linked with nutrient removal performance and EPS production. In order to mimic transient states of composition typical of industrial effluents, the reactor inlet medium periodically varied regarding to 2-FP presence and salt concentration.
- Impact of industrial wastewater on aerobic granules morphology and nitrification process in bioreactorsPublication . Paulo, Ana M. S.; Costa, Joana; Amorim, Catarina L.; Mesquita, Daniela P.; Ferreira, Eugénio C.; Castro, Paula M.L.
- Biodegradation of ofloxacin, norfloxacin, and ciprofloxacin as single and mixed substrates by Labrys portucalensis F11Publication . Amorim, Catarina L.; Moreira, Irina S.; Maia, Alexandra S.; Tiritan, Maria E.; Castro, Paula M. L.Fluoroquinolone (FQ) antibiotics are extensively used both in human and veterinary medicine, and their accumulation in the environment is causing an increasing concern. In this study, the biodegradation of the three most worldwide used FQs, namely ofloxacin, norfloxacin, and ciprofloxacin, by the fluoroorganic-degrading strain Labrys portucalensis F11 was assessed. Degradation occurred when the FQs were supplied individually or as mixture in the culture medium, in the presence of an easily degradable carbon source. Consumption of individual FQs was achieved at different extents depending on its initial concentration, ranging from 0.8 to 30 μM. For the lowest concentration, total uptake of each FQ was observed but stoichiometric fluoride release was not achieved. Intermediate compounds were detected and identified by LC-MS/MS with a quadrupole time of flight detector analyzer. Biotransformation of FQs by L. portucalensis mainly occurred through a cleavage of the piperazine ring and displacement of the fluorine substituent allowing the formation of intermediates with less antibacterial potency. FQ-degrading microorganisms could be useful for application in bioaugmentation processes towards more efficient removal of contaminants in wastewater treatment plants.
- Bacterial community dynamics within an aerobic granular sludge reactor treating wastewater loaded with pharmaceuticalsPublication . Amorim, Catarina L.; Alves, Marta; Castro, Paula M.L.; Henriques, IsabelPharmaceuticals are micropollutants often present in wastewater treatment systems. In this study, the potential impact of such micropollutants on the bacterial population within aerobic granular sludge (AGS) bioreactor was investigated. The AGS bacterial community structure and composition were accessed combining DGGE fingerprinting and barcoded pyrosequencing analysis. Both revealed the existence of a dynamic bacterial community, independently of the pharmaceuticals presence. The AGS microbiome at both phylum and class levels varied over time and, after stopping pharmaceuticals feeding, the bacterial community did not return to its initial composition. Nevertheless, most of the assigned OTUs were present throughout the different operational phases. This core microbiome, represented by over 72% of the total sequences in each phase, probably played an important role in biological removal processes, avoiding their failure during the disturbance period. Quantitative-PCR revealed that pharmaceuticals load led to gradual changes on the abundance of ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB) and polyphosphate-accumulating organisms (PAO) but their persistence during that phase demonstrated the resilience of such bacterial groups. AGS microbiome changed over time but a core community was maintained, probably ensuring the accomplishment of the main biological removal processes.