Percorrer por autor "Castro, Paula M. L."
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- 2-Fluorophenol degradation by aerobic granular sludge in a sequencing batch reactorPublication . Duque, Anouk F.; Bessa, Vânia S.; Carvalho, Maria F.; Kreuk, Merle K. de; Loosdrecht, Mark C. M. van; Castro, Paula M. L.Aerobic granular sludge is extremely promising for the treatment of effluents containing toxic compounds, and it can economically compete with conventional activated sludge systems. A laboratory scale granular sequencing batch reactor (SBR) was established and operated during 444 days for the treatment of an aqueous stream containing a toxic compound, 2-fluorophenol (2-FP), in successive phases. Initially during ca. 3 months, the SBR was intermittently fed with 0.22 mM of 2-FP added to an acetate containing medium. No biodegradation of the target compound was observed. Bioaugmentation with a specialized bacterial strain able to degrade 2-FP was subsequently performed. The reactor was thereafter continuously fed with 0.22 and 0.44 mM of 2-FP and with 5.9 mM of acetate (used as co-substrate), for 15 months. Full degradation of the compound was reached with a stoichiometric fluoride release. The 2-FP degrading strain was successfully retained by aerobic granules, as shown through the recovering of the strain from the granular sludge at the end of the experiment. Overall, the granular SBR has shown to be robust, exhibiting a high performance after bioaugmentation with the 2-FP degrading strain. This study corroborates the fact that bioaugmentation is often needed in cases where biodegradation of highly recalcitrant compounds is targeted.
- 4-fluorocinnamic acid biodegradation by a rhodococcus strainPublication . Amorim, Catarina L.; Carvalho, M. F.; Afonso, C. M. M.; Castro, Paula M. L.
- Acidogenic fermentation of brewers’ spent grain monitored through two-dimensional fluorescence spectroscopyPublication . Guarda, Eliana C.; Costa, Eunice; Gil, Cátia; Amorim, Catarina L.; Galinha, Claudia F.; Duque, Anouk F.; Castro, Paula M. L.; Reis, Maria A. M.Biological systems are commonly controlled and monitored through offline and time-consuming tools, which often impairs an effective and real-time response to counteract system disturbances. The feasibility of using two-dimensional (2D) fluorescence spectroscopy as a non-invasive, non-destructive, and real-time procedure to monitor the acidogenic fermentation of brewer’s spent grain (BSG) in a granular sludge reactor was evaluated. For that, the effect of pH fluctuations on the system response was used as a model to ascertain the 2D fluorescence spectroscopy applicability to monitor the process performance, namely, to predict the fermentation products (FP) and the soluble protein (SProt) concentrations in the effluent stream through mathematical analysis. The pH fluctuations over the course of the reactor’s operation altered the granules’ microbiome composition, leading to different effluent FP profiles. Fluorescence excitation–emission matrices (EEMs) were used with projection to latent structures (PLS) modeling to predict the FP and SProt concentrations in the effluent with average errors below 0.75 and 0.43 g L–1, respectively. Both models were able to capture the tendency of the data even when the accuracy of prediction was not so high. The combined approach of using 2D fluorescence spectroscopy and mathematical analysis seemed promising for real-time monitoring of the acidogenic fermentation of complex substrates.
- Actinobacteria isolated from wastewater treatment plants located in the east-north of Algeria able to degrade pesticidesPublication . Boufercha, Oumeima; Moreira, Irina Sousa; Castro, Paula M. L.; Boudemagh, AllaoueddineThe pollution of water resources by pesticides poses serious problems for public health and the environment. In this study, Actinobacteria strains were isolated from three wastewater treatment plants (WWTPs) and were screened for their ability to degrade 17 pesticide compounds. Preliminary screening of 13 of the isolates of Actinobacteria allowed the selection of 12 strains with potential for the degradation of nine different pesticides as sole carbon source, including aliette, for which there are no previous reports of biodegradation. Evaluation of the bacterial growth and degradation kinetics of the pesticides 2,4-dichlorophenol (2,4-DCP) and thiamethoxam (tiam) by selected Actinobacteria strains was performed in liquid media. Strains Streptomyces sp. ML and Streptomyces sp. OV were able to degrade 45% of 2,4-DCP (50 mg/l) as the sole carbon source in 30 days and 84% of thiamethoxam (35 mg/l) in the presence of 10 mM of glucose in 18 days. The biodegradation of thiamethoxam by Actinobacteria strains was reported for the first time in this study. These strains are promising for use in bioremediation of ecosystems polluted by this type of pesticides.
- Activity of nitrifying bacteria in aerobic granular sludge treating food industry wastewaterPublication . Paulo, Ana M. S.; Amorim, Catarina L.; Castro, Paula M. L.Aerobic Granular Sludge (AGS) is an innovative wastewater biological treatment, which uses less energy and space compared to other technological solutions. AGS presents a diverse microbial community responsible for the simultaneous removal of carbon and nutrients. These communities are protected by extracellular polymeric substances (EPS), which provide a compact structure to the granules. As a result, bacteria present in the aerobic granules are more resistant to variable wastewater composition, as commonly produced in food industry. In this study, carbon and NH4+ removal from a fish canning plant wastewater was evaluated using an AGS-SBR (sequential batch reactor), operated during 90 days. Chemical oxygen demand (COD) at the outlet was below the discharge limit of 125 mg O2 L-1 throughout the operation. Nitrification occurred during the first 23 days of operation. Between days 24 and 60, nitrification was completely inhibited, without ammonium removal from the wastewater. Nitrifying bacteria recovered their activity right after a decrease in the wastewater organic load, showing that the inhibition of the nitrification process was reversible. This study will contribute to our knowledge on the application of the AGS process to food industry wastewater treatment.
- Adaptative biological response of aerobic granular sludge to events of single or combined wastewater related stressorsPublication . Alves, Marta; Henriques, Isabel; Castro, Paula M. L.; Amorim, Catarina L.Wastewater comprises various stressors and their individual and combined immediate effects on aerobic granular sludge (AGS) are still underexplored. In this study, the AGS was exposed for 24 hours to wastewater with varying salt concentrations (up to 30 g NaCl L⁻¹) alongside pharmaceuticals (diclofenac, DCF or carbamazepine, CBZ). Differences in extracellular polymeric substances (EPS) production and composition were observed between single and combined stressor exposures. The removal of pharmaceuticals was influenced by the wastewater salinity level and the type of pharmaceutical, with a positive correlation found between the EPS polysaccharides content and the removal efficiency at salinity levels up to 10 g NaCl L⁻¹ . The combination of salinity and pharmaceuticals in wastewater also impacted the AGS bacteriome composition, with the bacteriome of the AGS not-exposed to stressors showing greater similarity to that of AGS exposed to DCF than to that exposed to CBZ, at each wastewater salinity level. Functional profiling suggested that short-term exposure to stressors slightly increased the relative abundance of mismatch repair, cell motility, and homologous recombination functions in the AGS microbiome. Summing up, the stressors impact on AGS bacteriome structure and EPS production varies depending on the pharmaceutical and whether it is combined with salt or not. This study unveiled the immediate AGS response to both single and combined stressors exposure, but a more thoughtful characterization of the bacteriome composition over the early adaptation period to stressors is needed to understand the community succession and to identify key microbial groups.
- Adsorption of fluorobenzene onto granular activated carbon: Isotherm and bioavailability studiesPublication . Carvalho, M.F.; Duque, A.F.; Gonçalves, I.C.; Castro, Paula M. L.The adsorption of a recalcitran fluoroaromatic compound, fluorobenzene (FB), onto granular activated carbon (GAC) was evaluated. The respective isotherm was obtained and the Langmuir, Freundlich and Redlich–Peterson models were fitted to the experimental data, with the Redlich–Peterson model giving the best fitting. Freundlich model also provided a good fit but the Langmuir model could not adequately fit the experimental data, especially at high FB concentrations. Maximal adsorption capacity of FB onto GAC was foundto be 388 mg of FB per gram of GAC. The reversibility of the adsorption of FB onto GAC was investigated, both in the absence and presence of microorganisms. Abiotic desorption of FB occurred to a small extent (between 3% and 22%, for amounts of FB initially adsorbed to the GAC between 37 and 388 mg g 1), and bioregeneration of GAC was shown to occur when the matrix was exposed to a FB degrading culture, with 58–80% of the adsorbed FB being biodegraded. A residual amount of FB showed not to be bioavailable, suggesting that part of the adsorbed FB may be irreversibly bound. The fraction of the non-bioavailable FB increased at higher amounts of adsorbed FB, from 19% to 33%. The results indicate that the GAC employed in this study has a good capacity to adsorb FB and that bioregeneration of this matrix is a feasible process.
- Advancing crop resilience and soil health through agroecological practicesPublication . Sousa, Ana S. S.; Godinho, Mariana; Oliveira, Manuel; Soares, Rui; Castro, Paula M. L.; Pereira, Sofia I.A.The transition toward sustainable agriculture demands innovative approaches that can simultaneously improve crop productivity, protect natural resources, and reinforce long-term ecosystem resilience. Agroecological practices (AE), including crop diversification, conservation tillage, and integrated pest management, have emerged as essential pillars in building farming systems that balance production goals with environmental stewardship. Within this context, biofertilizers and cover crops represent two particularly promising strategies. Biofertilizers enhance nutrient availability, plant growth, and yields while reducing dependence on synthetic inputs, whereas cover crops contribute to soil fertility, water retention, and biodiversity, ultimately improving the overall sustainability of agricultural landscapes. Ongoing research and field applications across several EU-funded initiatives are advancing these strategies in diverse cropping systems, including vineyards, maize, and tomato. Projects such as ReCROP, which investigated biotechnological tools and sustainable practices to boost crop resilience and soil biodiversity in Mediterranean systems, and Sun2Fork, which examines solar-driven technologies and microbial inoculants to enhance tomato salinity tolerance in soilless cultivation, highlight the breadth of innovation underway. More recently, the VinAE project is establishing pilot vineyards across five major wine-producing countries to evaluate how AE influence grapevine performance, must quality, water use efficiency, and below- and above-ground biodiversity. In Portugal, field experiments at Quinta dos Aciprestes (Real Companhia Velha) are assessing the combined effects of hydrogels, cover crops, and microbial inoculants on grapevine performance.
- Advancing crop resilience and soil health through agroecological practicesPublication . Sousa, Ana S. S.; Godinho, Mariana; Oliveira, Manuel; Soares, Rui; Castro, Paula M. L.; Pereira, Sofia I. A.
- Aerobic and anoxic growth and nitrate removal capacity of a marine denitrifying bacterium isolated from a recirculation aquaculture systemPublication . Borges, Maria-Teresa; Sousa, André; Marco, Paolo De; Matos, Ana; Hönigova, Petra; Castro, Paula M. L.Bacterial biofilters used in marine recirculation aquaculture systems need improvements to enhance nitrogen removal efficiency. Relatively little is known about biofilter autochthonous population structure and function. The present study was aimed at isolating and characterizing an Autochthonous denitrifying bacterium from a marine biofilter installed at a recirculation aquaculture system. Colonization of four different media in a marine fish farm was followed by isolation of various denitrifying strains and molecular classification of the most promising one, strain T2, as a novel member of the Pseudomonas fluorescens cluster. This strain exhibits high metabolic versatility regarding N and C source utilization and environmental conditions for growth. It removed nitrate through aerobic assimilatory metabolism at a specific rate of 116.2 mg NO3-N g dw _1 h _1. Dissimilatory NO3-N removal was observed under oxic conditions at a limited rate, where transient NO2-N formed represented 22% (0.17 mg L _1) of the maximum transient NO2-N observed under anoxic conditions. Dissimilatory NO3-N removal under anoxic conditions occurred at a specific rate of 53.5 mgNO3-N g dw _1 h _1. The isolated denitrifying strain was able to colonize different materials, such as granular activated carbon (GAC), Filtralite and Bioflow plastic rings, which allow the development of a prototype bioreactor for strain characterization under dynamic conditions and mimicking fish-farm operating conditions.