Percorrer por autor "Oliveira, Ana T."
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- Meat processing wastewater valorised through microalgae productionPublication . Sousa, Ana S. S.; Oliveira, Ana T.; Castro, Paula M. L.; Amorim, Catarina L.The treatment of meat processing wastewater (MPWW) is crucial to mitigating its environmental impact but remains challenging due to its high organic content and contents of nitrogen and solids. The novelty of this work lies in evaluating the treatment and valorization of real MPWW with variable composition, as well as the process scalability, in a fed-batch raceway reactor while exploring the synergistic microbial interactions within the system. A microalgae-based consortium with proven bioremediation capacity was used as biomass. In batch assays, the microalgae-based biomass thrived in raw MPWW, demonstrating synergistic interactions with the native wastewater microbiome that facilitated organic carbon and total nitrogen removal. In sieved and sedimented MPWW, the COD removal rates were higher (1097.5±22.2 mg L?¹ day?¹) than in raw MPWW (828.5±60.5 mg L?¹ day?¹), and the microalgae growth rate also improved. In a laboratory-scale raceway reactor, in fed-batch mode, COD removal rates ranging from 181.3 to 806.3 mg L?¹ day?¹ were achieved, despite variable wastewater composition. The nitrogen mass balance indicated that ammonium, nitrate, and nitrite were consumed. The increase in photosynthetic pigments’ concentration throughout operation, from 0.4 to 17.9 µg mL?¹, demonstrated robust microalgae growth under variable wastewater compositions. The biomass microbiome, initially dominated by microalgae from the Chlorophyta and Ciliophora phyla, evolved to include other eukaryotic taxa (including yeast and fungi) and likely bacteria. The microbiome's adaptability and its microbial diversity appeared to be key drivers in enhancing biological removal processes. This work advances microalgae-based processes for treating and valorising MPWW by highlighting microbial ecology’s role in system resilience and efficiency and giving insights in process scalability, showcasing its robustness for real-world applications.
- Microalgae allow reducing aeration requirements and improve the efficiency of granular sludge treating coastal aquaculture streams aimed at recirculationPublication . Oliveira, Ana T.; Castro, Paula M. L.; Amorim, Catarina L.Water pollution has become a global issue of increasing environmental concern. In the journey towards the energy and carbon neutrality of wastewater treatment processes, an increasing interest has been placed in microalgal-bacterial granular sludge (MBGS) systems. The symbiotic relationship between microalgae and bacteria in granules in terms of gas exchange could lead to energy savings and greenhouse gases emission reduction. This study aimed to ascertain on the minimum dissolved oxygen content needed to efficiently remove pollutants and allow for water recycling in coastal aquaculture facilities. For that, a photo-sequencing batch reactor was inoculated with microalgae-bacterial granular sludge and operated under a stepwise decrease of the airflow rate from 3.0 to 1.5 L min-1 for 134 days. The removal efficiency of chemical oxygen demand (COD) was kept at high level (47 to 77%). Complete ammonium removal was achieved throughout operation, independently of the applied airflow rate whilst nitrite and nitrate removal improved at lower airflow rates (< 2.0 L min⁻¹). In fact, the mass balance on nitrogen species further revealed that the overall nitrogen removal improved indicating that water of quality for recirculation can be obtained at lower airflow rates (<2.0 L min⁻¹). Although the reduction of the airflow rate till ca. 1.5 L min⁻¹ benefited the reactor performance, outgrowth of filamentous microorganisms started to occur, compromising the quick and efficient separation of the biomass from treated water. The MBGS system operated under extremely low airflow rates represents a promising solution in recirculation aquaculture systems, rendering water with chemical quality that complied with marine fish toxicity limits, whilst potentially reducing the aquaculture farm operational costs. Nevertheless, an airflow rate threshold should not be surpassed to prevent the outgrowth of filamentous microbes.
- Mycelia inactivation processes – maintaining the flexibility and strength of mycelium-based biocompositesPublication . Oliveira, Ana T.; Ramos, Miguel A.; Castro, Paula M. L.The current trend towards a sustainable and circular economy proposes the development and use of bio-based materials from renewable resources. Mycelium-based biocomposites (MBB), which consists of defragmented lignocellulosic particles linked by dense mycelium, are an ecological and innovative solution to replace petroleum-based products. MBB have shown advantageous properties, such as acoustic insulation, fire resistance, and the absence of harmful synthetic chemical components. These properties are the basis for the production and use of MBB for a wide range of applications, including paper, textiles, foams for packaging material, vehicle parts, and electronic equipment packaging materials. Briefly, MBB production is achieved through the sterilization the biomass, inoculation and incubation with selected fungi, homogenization, and interruption of fungal growth (or inactivation). Most MBB go through a heating treatment to inactivate the mycelia. However, that treatment results in rigid biocomposites with low flexibility. This work investigated the performance of alternative inactivation methods aiming to achieve flexible but sturdy MBB. Low temperature treatments and CuSO4 were tested in biocomposites obtained from two fungi strains. The inactivation efficiency was evaluated through a cell viability assay, MTT assay. The physical properties of the resulting biocomposites were also assessed. Spraying MBB with a CuSO4 solution did not efficiently inactivate the fungi. Although the low temperatures seemed to have inactivated the fungi two days after treatment (ca. 1% cell viability), 15 days later the mycelia resumed growth again (34% cell viability). Therefore, those treatments did not efficiently inactivate the fungi but left them in a latent dormancy state. None of the tested methods compromised the biocomposites’ flexibility features. Further studies need to be conducted to identify inactivation methods that allow the production of MBB with a more diverse range of physical characteristics to expand their application potential.
- Optimizing the dissolved oxygen requirements for effective pollutant removal from coastal aquaculture wastewater aiming at water recyclingPublication . Oliveira, Ana T.; Castro, Paula M. L.; Amorim, Catarina L.Wastewater treatment presents a pressing global challenge, emphasizing the urgent need for more sustainable solutions. In the pursuit of energy and carbon neutrality, microalgal-bacterial granular sludge (MBGS) systems have emerged as a promising alternative, leveraging the symbiotic relationship between microalgae and bacteria within granules in terms of gas exchange. MBGS systems offer efficient treatment but also hold the promise for substantial energy savings and greenhouse gas emissions reduction. The present study aimed to ascertain on the dissolved oxygen threshold required for efficient pollutants removal from coastal aquaculture aiming at water recycling in industrial settings.
- Optimizing the dissolved oxygen requirements for effective pollutant removal from coastal aquaculture wastewater aiming at water recyclingPublication . Oliveira, Ana T.; Castro, Paula M. L.; Amorim, Catarina L.Wastewater treatment presents a pressing global challenge, emphasizing the urgent need for more sustainable solutions. In the pursuit of energy and carbon neutrality, microalgal-bacterial granular sludge (MBGS) systems have emerged as a promising alternative, leveraging the symbiotic relationship between microalgae and bacteria within granules in terms of gas exchange. MBGS systems offer efficient treatment but also hold the promise for substantial energy savings and greenhouse gas emissions reduction.The present study aimed to ascertain on the dissolved oxygen threshold required for efficient pollutants removal from coastal aquaculture aiming at water recycling in industrial settings. To accomplish this, a MBGS system was applied for the treatment of aquaculture wastewater and underwent a gradual reduction in the airflow rate from 3.0 to 1.5 L min⁻¹ over 134 days. Regardless of the airflow rate, complete ammonium removal was consistently achieved, while lower airflow rates appeared to enhance nitrite and nitrate removal. The composition of treated effluents met toxicity limits for fish, enabling water reuse in aquaculture facilities. However, if the airflow rate was reduced to about 1.5 L min⁻¹, outgrowth of filamentous microorganisms started to occur on granules surface, compromising their efficient separation from the treated water.Aeration typically contributes significantly to energy consumption in wastewater treatment processes. Utilizing MBGS systems can effectively reduce aeration needs, up to a certain level, without compromising the treatment performance, thus improving the ecological footprint of the treatment process.
- Rapid granulation and stable performance of a microalgal-bacterial granular sludge system treating saline wastewaterPublication . Alves, Marta; Oliveira, Ana T.; Castro, Paula M. L.; Amorim, Catarina L.