Browsing by Author "Oliveira, Ana S."
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- Bioaugmentation of Aerobic Granular Sludge with specialized degrading granules treating 2-fluorophenol wastewaterPublication . Oliveira, Ana S.; Amorim, Catarina L.; Zlopasa, Jure; Lin, Yumei; Loosdrecht, Mark C. M. van; Castro, PaulaThe industry growth has been accompanied by an increase in the amount of industrial chemicals being released into the environment. Indigenous microbial communities in wastewater biotreatment processes are not always effective in removing xenobiotics. This work aimed to evaluate the efficiency of a new bioaugmentation strategy in an aerobic granular sludge sequencing batch reactor (AGS-SBR) system fed with 2-fluorophenol (2-FP). Bioreactor performance in terms of phosphate and ammonium removal, 2-FP degradation and chemical oxygen demand (COD) was evaluated. The new bioaugmentation strategy consisted in producing granules using extracellular polymeric substances (EPS) extracted from AGS as a carrying matrix and a 2-FP degrading strain, Rhodococcus sp. FP1. The produced granules were used for the bioaugmentation of a reactor fed with 2-FP. Shortly after bioaugmentation, the produced granules broke down into smaller fragments inside the bioreactor, but 2-FP degradation occurred. After 8 days of bioaugmentation, 2-FP concentration inside the reactor started to decrease, and stoichiometric fluorine release was observed 35 days later. Phosphate and ammonium removal also improved after bioaugmentation, increasing from 30% to 38% and from 20 to 27%, respectively. Complete ammonium removal was only achieved when 2-FP feeding stopped, and phosphate removal was not recovered during operation time. COD removal also improved after the addition of the produced granules. The persistence of Rhodococcus sp. FP1 in the reactor was followed by qPCR. Rhodococcus sp. FP1 was detected 1 day after in the AGS and up to 3 days after bioaugmentation at the effluent. Nevertheless, the 2-FP degradative ability remained thereafter in the granules. Horizontal gene transfer could have happened from the 2-FP degrading strain to indigenous microbiome as some bacteria isolated from the AGS, 3 months after bioaugmentation, were able to degrade 2-FP. This study presents a promising and feasible bioaugmentation strategy to introduce specialized bacteria into AGS systems treating recalcitrant pollutants in wastewater.
- Bioremediation of coastal aquaculture effluents spiked with florfenicol using microalgae-based granular sludge – a promising solution for recirculating aquaculture systemsPublication . Oliveira, Ana S.; Alves, Marta; Leitão, Frederico; Tacão, Marta; Henriques, Isabel; Castro, Paula M. L.; Amorim, Catarina L.Aquaculture is a crucial industry in the agri-food sector, but it is linked to serious environmental problems. There is a need for efficient treatment systems that allow water recirculation to mitigate pollution and water scarcity. This work aimed to evaluate the self-granulation process of a microalgae-based consortium and its capacity to bioremediate coastal aquaculture streams that sporadically contain the antibiotic florfenicol (FF). A photo-sequencing batch reactor was inoculated with an autochthonous phototrophic microbial consortium and was fed with wastewater mimicking coastal aquaculture streams. A rapid granulation process occurred within ca. 21 days, accompanied by a substantially increase of extracellular polymeric substances in the biomass. The developed microalgae-based granules exhibited high and stable organic carbon removal (83-100%). Sporadically wastewater contained FF which was partially removed (ca. 5.5-11.4%) from the effluent. In periods of FF load, the ammonium removal slightly decreased (from 100 to ca. 70%), recovering 2 days after FF feeding ceased. A high-chemical quality effluent was obtained, complying with ammonium, nitrite, and nitrate concentrations for water recirculation within a coastal aquaculture farm, even during FF feeding periods. Members belonging to the Chloroidium genus were predominant in the reactor inoculum (ca. 99%) but were replaced from day-22 onwards by an unidentified microalga from the phylum Chlorophyta (>61%). A bacterial community proliferated in the granules after reactor inoculation, whose composition varied in response to feeding conditions. Bacteria from the Muricauda and Filomicrobium genera, Rhizobiaceae, Balneolaceae, and Parvularculaceae families, thrived upon FF feeding. This study demonstrates the robustness of microalgae-based granular systems for aquaculture effluent bioremediation, even during periods of FF loading, highlighting their potential as a feasible and compact solution in recirculation aquaculture systems.
- Increased extracellular polymeric substances production contributes for the robustness of aerobic granular sludge during long-term intermittent exposure to 2-fluorophenol in saline wastewaterPublication . Oliveira, Ana S.; Amorim, Catarina L.; Mesquita, Daniela P.; Ferreira, Eugénio C.; Loosdrecht, Mark van; Castro, Paula M. L.Industrial effluents often contain organic pollutants and variable salinity levels, making their treatment challenging. The high content of extracellular polymeric substances (EPS) in the aerobic granular sludge (AGS) is thought to protect the microbial communities from stressful conditions. Ammonium and phosphate removal, EPS production, and granular morphology were assessed in a lab-scale AGS reactor operated during 138 days at continuous low or moderate salinity levels (1.41–6.46 g/L of NaCl) and intermittent short-term loadings of a fluoroorganic pollutant, 2-fluorophenol (2-FP, 20 mg/L). 2-FP was not degraded throughout operation. Ammonium removal efficiency was drastically affected whenever 2-FP stressor was present, decreasing from 99 % to non-detectable conversion levels, but completely recovering after 2-FP feeding ceased. Phosphate removal, initially disturbed by exposure to stress conditions, recovered with time, even when stressors were still present. Complete phosphate removal did not occur in periods when nitrite temporarily accumulated after nitrification started to recover. EPS composition and concentration in AGS varied during operation, initially decreasing from 133 to 34 mg/g VSS of AGS, during the stress phases but recovering thereafter to 176 mg/gVSS of AGS. Breakage of granules into smaller ones occurred at two different operational moments due to stressors presence. The presence of 2-FP and moderate salinity levels in wastewater had more immediate detrimental effects on nutrients removal than on EPS production. The AGS system capacity to recover the nutrient removal performance and EPS production, after the withdrawal of 2-FP from the inlet stream reinforced its robustness to deal with industrial wastewaters.
- 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.
- Microalgae allow reducing aeration requirements and improve the efficiency of granular sludge treating coastal aquaculture streams aimed at recirculationPublication . Oliveira, Ana S.; Castro, Paula M. L.; Amorim, Catarina L.
- Microalgae granular systems feasible for the treatment of marine aquaculture streams containing florfenicol antibioticPublication . Oliveira, Ana S.; Alves, Marta; Castro, Paula M. L.; Amorim, Catarina L.Land-based aquaculture industries generate high volumes of wastewater containing low concentration of carbon and nutrients that, if not properly handled, can pose a major environmental impact on the receiving water bodies and ecosystems. To face the current water scarcity and mitigate the pollution triggered by the rapid expansion of these industries, the development of treatment systems that allow water recirculation is of utmost importance. Florfenicol (FF), a broad-spectrum antibiotic, is sporadically present in aquaculture streams which may cause deleterious effects on the biological wastewater treatment systems and on the receiving ecosystems. This work aimed to evaluate the granulation of microalgae biomass with marine aquaculture effluents, without the need of any carrier, and its ability to remove nutrients in streams containing FF. A photo-sequencing batch reactor was inoculated with a suspended microalgae consortium enriched from water collected at a marine aquaculture facility and was fed with synthetic wastewater mimicking marine aquaculture streams. Rapid granulation occurred, with microalgae granules representing ca. 49% of the total reactor biomass around day-21. Overall, the microalgae granules exhibited high and stable organic carbon and ammonium removal efficiencies of more than 40 and 90%, respectively. During FF shock loads, ammonium removal efficiency slightly decreased to ca. 80% while carbon removal was unaffected. Nitrate was the main N species in the reactor effluent, but nitrite concentration exceeds the fish toxicity limit for adequate water recirculation. Up to 11% of the fed FF was removed in the reactor. Production of pigments, biomarkers of cell viability, increased exponentially until day-64, ca. 23 times, stabilizing thereafter. This study emphasizes the robustness of microalgae granules to remove carbon and ammonium from marine aquaculture streams, even in periods of FF load. The implementation of such systems in marine aquaculture facilities is a feasible and compact solution, however further improvement of the removal performance is needed to reduce nitrite levels if water recirculation is aimed for.
- Microalgae-bacterial granular sludge systems - on the road for more sustainable processes in the aquaculture sectorPublication . Oliveira, Ana S.; Alves, Marta; Castro, Paula M. L.; Amorim, Catarina L.With population growth and stagnation of capture fisheries, the aquaculture sector has been challenged to achieve remarkable production targets to meet the ever-increasing fish demand. However, land-based aquaculture industries need to capture high water volumes from nearby water bodies to ensure an adequate production and, consequently, high wastewater volumes, containing organic carbon, nutrients, and often contaminants of emerging concern, are produced. If not properly handled, aquaculture effluents pose a threat to receiving aquatic ecosystems. The rapid expansion of these industries, facing the increased demand for food worldwide, is only possible if more sustainable practices are adopted. To face the current water shortages and protect water resources, the development of environmentally friendly treatment systems that allow water recirculation is of utmost importance. This work aimed to develop a microalgae-bacteria granular sludge system able to efficiently treat marine aquaculture effluents so they can meet the requirements for recirculation. A photo-sequencing batch reactor was inoculated with a phototrophic microbial consortium obtained from water streams in a marine aquaculture facility and was fed with wastewater mimicking marine aquaculture streams. The aggregation of the microbial biomass occurred rapidly and, on day-21, ca. 49% of the total reactor biomass was in the form of granules. The system exhibited high and stable organic carbon removal (>80%), even when florfenicol, an antibiotic widely used in aquaculture, was present in the wastewater. Concerning the nitrogen content, a high-chemical quality effluent was obtained, complying with ammonium, nitrite, and nitrate concentrations for water recirculation within a marine aquaculture farm, even in periods where florfenicol was present in the wastewater. In addition, the dissolved oxygen levels in the treated effluents where within the ideal range for fish growth thus reducing the need for oxygenation and, consequently, the farms operational costs. Additionally, the coexistence of microalgae and bacteria within the granules allowed to treat wastewater at low air flow rates potentially reducing the energy needed for system’s aeration. Microalgae-bacterial granular sludge systems can contribute for the aquaculture sector sustainability as they enable to reduce energy and water usage whilst ensuring environmental protection.
- Microalgae-bacterial granular sludge under reduced aeration efficiently treat coastal aquaculture streams aimed at recirculationPublication . Oliveira, Ana S.; Castro, Paula M. L.; Amorim, Catarina L.
- Microalgal biomass production in a raceway system using meat processing water as feedstockPublication . Sousa, Ana S. S.; Oliveira, Ana S.; Morais, Rui M. S. C.; Castro, Paula M. L.; Amorim, Catarina L.
- Microalgal biomass production in a raceway system using meat processing water as feedstockPublication . Sousa, Ana S. S.; Oliveira, Ana S.; Morais, Rui M. S. C.; Castro, Paula M. L.; Amorim, Catarina L.Meat industry produces large volumes of water streams with a complex and high strength composition. The use of microalgae for reducing the organic and nutrient load of such streams is promising with the plus that the microalgae biomass produced can be collected as an added value product, and further used for a range of applications. In this study, the microalgae ability to grow in meat processing wastewater, while improving water quality, was assessed. For that, a prototype raceway system was inoculated with a microalgae consortium and was fed with wastewater collected at a meat processing industry. The wastewater consisted of a mixture of streams from the cleaning of cooking drums and the cooling processes. Over 2 months, the raceway was operated in fed-batch mode, under varying wastewater composition. A total of 7 fed-batch cycles were performed, each using a different batch of wastewater collected at the industrial facility.In the first feeding cycle, an organic carbon reduction of ca. 91% was achieved, with a removal rate of 685 mg l-1 d-1. On the subsequent feeding cycles, the organic carbon removal rate increased up to 806 mg l-1 d-1. Ammonium concentrations fluctuated over time, probably due to the complex composition of the wastewater. Nevertheless, longer fed-batch cycles seemed to improve ammonium removal. Microalgae biomass productivity increased over time, accompanied by the development of an intense green coloration. The operation by repeated fed batch seemed feasible for microalgae cultivation in meat processing wastewater, allowing concomitantly its remediation.