UB - Comunicações em actas de encontros científicos internacionais
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- An expedite methodology for identification of inorganic contaminants in biomass origin feedstock: wavelength dispersive x-ray fluorescence (WD-XRF) spectrometryPublication . Crujeira, Teresa; Trancoso, Maria Ascensão; Oliveira, Ana CristinaABSTRACT: The use of biomass feedstock for bioenergy production has increased in recent years. In the context of a circular economy, wastes such as municipal solid wastes and industrial wastes (namely by-products from agrofood wastes, agro-livestock wastes and sewage sludge) have been tested as new feedstocks of biomass origin. However, the presence of some inorganic contaminants in these new feedstocks might be problematic for thermochemical and biochemical conversion processes. Wavelength Dispersive X-Ray Fluorescence (WD-XRF) spectrometry is an easy and fast technique that uses only a small amount of sample, presenting a low contamination risk and is a non-destructive methodology. Thus, if potential contaminants are identified, then samples remain available for subsequent analysis.
- GIS-Based Model to Identify Marginal Soils for Bioenergy ProductionPublication . Abreu, Mariana; Reis, Alberto; Fernando, Ana Luisa; Quental, Lídia; Patinha, Pedro; Gírio, FranciscoABSTRACT: Energy crops are industrial species (woody, perennial, and annual species, among others) that can generate biofuels, energy, and bioproducts. Due to their tolerance, there is an interest to grow energy crops in marginal/contaminated/degraded soils, avoiding Indirect Land Use Change (ILUC) burdens. Therefore, this study aims at the development and use of Geographic Information System (GIS) tools to spatially relate land-use selection and optimal species allocation, as an useful decision support systems (DSS), modelled to determine adequate marginal areas, inadequate for food and feed crops. ArcGIS software was used as a GIS tool, and parameters associated with areas considered to be marginal in mainland Portugal were identified. To identify marginal soils, it is necessary to know what type of criteria applies. It was considered the Regulation EU(1305)2013-Annex III, which details all the criteria and the respective parameters, that marginal soil should present being these, the base of this work. Considering all these criteria, a search in several databases was realized to collect the data that exist and how all these could be utilized to determine marginal soils in mainland Portugal. The maps obtained show that marginal soils in Portugal represent less than 10% of the territory.
- Application of ionic liquids for bacterial carotenoid extractionPublication . Salgado, Francisco; Silva, Tiago; Alves, Luís; Roseiro, J. Carlos; Lukasik, Rafal M.; Paixão, Susana M.ABSTRACT: One of the ways to make microbial bioprocesses more economically viable is to enhance valorization of high added value products resulting from the biomass, like carotenoids, which have a high market value. To recover these pigments from microbial biomass a good extraction method is required. Solvent extraction is one of the methods commonly used to extract carotenoids, however, solvent extractions are both material and time-consuming, and moreover also present some health and safety concerns. Ionic liquids (ILs) are a promising step forward to tackle some of these problems, even with their high price, and has been tested for the extraction of microorganism’s components. These “molten salts” are a group of compounds that have been known for a long time, but only in the last decades they have been attracting more attention from both researchers and industry. ILs are solvents that have a high solvation power for a wide range of molecules. ILs are salts with a melting point below 100ºC, which possess unique properties that depend on both the cation and anion present, high thermal and chemical stability, a large electrochemical window, great solvent power, non-flammability, and a negligible vapor pressure. Their versatility is one of their most attractive features, making them adaptable to many technologies. Therefore, ILs can be used to facilitate chemical reactions, extraction and separation, biotransformation, and can be used in biorefineries and other processes. As shown in previous works, Gordonia alkanivorans strain 1B has the capacity to produce carotenoids, however, since it was originally isolated form hydrocarbon rich environments, it is highly resistant to different organic solvents commonly used in extraction protocols. This makes the process slow and laborious, lowering yields and increasing solvent spending. As such, new extraction protocols must be developed and tested to obtain higher pigments yield. So, herein, the potential of ILs for carotenoids extraction was evaluated, since these compounds have been described as a good option to extract pigments produced by microorganisms.
- Biodesulfurization biorefinery using Gordonia alkanivorans strain 1B: life cycle inventory of the integrated processPublication . Silva, Tiago; Silva, Carla; Paixão, Susana M.; Alves, LuísABSTRACT: High sulfur concentrations are a problem common to fossil fuels and derivatives (such as oil and coal), as well as many new generation fuels and biofuels (such as pyrolysis oils, syngas, biogas or even biodiesel). If the sulfur present in these fuels is released into the atmosphere it can result in SO2/SOx emissions, leading to environmental damage, and health issues. Transportation fuels have sulfur limits that go below 5000 ppm in ships, 3000 ppm in airplanes and 10 ppm in cars, and without treatment fuels can have several thousand ppm of sulfur. As such, they must be submitted to desulfurization, typically through a thermochemical process known as hydrodesulfurization, in which H2 is combined with the fuel at high temperatures and pressures, in the presence of metal catalysts. However, this process has significant environmental impacts. Usually, it depends on hydrogen and heat/steam produced from natural gas, totalizing 4.17 kg natural gas per 2.89 kg sulfur removed. It also involves high electricity and water consumption (approximately 2.9 kWh and 86.9 kg, respectively, per 2.89 kg sulfur removed). Furthermore, these impacts are greater for lower sulfur demands (Burgess & Brennan, 2001). Thus, there has been a search for alternative/complementary processes, one of which is biodesulfurization (BDS). It consists of the use of microorganism that consume the sulfur present in the fuels, at ambient temperature and pressure, without the need for metal catalysts. BDS still presents several bottlenecks, common to many microbial processes, such as low conversion rates and high production costs for the microbial biocatalyst. To surpass these limitations researchers have pursued different strategies: minimization/optimization of culture medium and culture conditions; employment of cheaper alternative nutrient sources; exploitation of added value products. Gordonia alkanivorans strain 1B is a bacterium known for its biodesulfurization properties. It has demonstrated several characteristics which make it interesting: it can perform BDS of different compounds, several of which extremely recalcitrant for the thermochemical process; it has very low nutritional needs; it can be cultivated on several alternative carbon sources; it has been shown to produce two different types of added value products: carotenoids and biosurfactants (Alves et al., 2015; Silva et al., 2020, 2022). Therefore, G. alkanivorans strain 1B is the ideal candidate for a biodesulfurization biorefinery, that simultaneously removes sulfur from fuels and produces carotenoids and biosurfactants.
- A fast and effective analytical method to quantify the emulsifying activity: design and validationPublication . Alves, Luís; Tavares, João; Silva, Tiago; Paixão, Susana M.ABSTRACT: Biosurfactants (BS) and bioemulsifiers (BE) are amphiphilic molecules that are produced by a wide range of microorganisms. According to Willumsen and Karlson, BS/BE are both surface active biomolecules, but while the surfactants play the role of surface tension reduction, emulsifiers are involved in formation and stabilization of emulsions. However, some biomolecules possess both surfactant and emulsifying properties, which contributes to their unique features, including high biodegradability, low toxicity, effectiveness at extremes of temperature, pH and salinity, and special biological activities (e.g., antimicrobial, antiviral, anticancer, etc). These attributes make them an alternative to their chemical counterparts and allows them to have key roles in several fields. In fact, the chemical composition of BS and BE is different, and this may contribute to their specific roles in nature and biotechnological applications; however, both BS/BE have recognized emulsifying properties, which are the focus of this study. The idea of quantifying the emulsifying activity rather than quantifying the emulsifiers and/or surfactants themselves has been studied before. The concept that stands out is the emulsification index (E24: % emulsification after 24 h) proposed by Cooper and Goldenberg [4], which is still applied, and some of its adaptations such as the one proposed by Trebbau de Acevedo and McInerney. These authors have defined one unit of emulsifying activity as the amount of emulsifier that results in an emulsification (E24) of 20%. Although theoretically simple, these approaches require considerable sample volume, have a long wait (24 h) and are lengthy. Moreover, they can be subjective, since two substances might induce complete emulsion at 24 h, with one resulting in a much denser emulsion. This may indicate more BS/BE activity; however, it is not easily comparable, or demonstratable. Furthermore, due to nature of emulsions and the factors that influence them, small differences in test conditions, such as shape or size of the tubes, or nature of the hydrophobic layer, can generate drastic differences, which hinders reproducibility between authors.
- A novel microbial biosurfactant/bioemulsifier: production and characterizationPublication . Silva, Tiago; Paixão, Susana M.; Tavares, João; Alves, LuísABSTRACT: Currently there is an immediate need for new and more sustainable production methods in most industries. The detergent industry, frequently associated with negative environmental impacts, is also in need of new alternatives, such as biosurfactants/bioemulsifiers (BS/BE). These are naturally synthetized compounds, classified as amphiphilic, for having both hydrophobic and hydrophilic properties. Their application results in a reduction of the surface tension between two immiscible phases, facilitating the mixture of different substances such as water and oil, or water and air (Tavares et al., 2021). BS/BE present several advantages over conventional detergents, they have lower toxicity and greater biodegradability, resulting in lower negative impacts to both consumers and ecosystems. Furthermore, these compounds present antibiotic, antiviral and antioxidant properties. They can be used in a broad range of pH, temperature and salinity and are effective at small concentrations. This makes them interesting for many other industries, such as food, cosmetics, pharmaceutical and chemical. BS/BE are commonly produced by microorganisms found in particular environments such as oil wells, hydrocarbon contaminated soils and solid waste lixiviates. These compounds facilitate the access to hydrophobic nutrient sources abundant in these environments, while also increasing the resistance of the microorganisms to such toxic environments. Gordonia alkanivorans strain 1B, is a bacterium with significant biotechnological potential, which was isolated from oil contaminated soils (Alves et al., 2005). It is mostly known for its biodesulfurizing properties, carotenoid production and broad catabolic range (Silva et al., 2016). The present work focuses on the potential of this strain to produce BS/BE compounds, initial purification and characterization.
- Optimization of a biphasic biodesulfurization systemPublication . Silva, Tiago; Paixão, Susana M.; Roseiro, J. Carlos; Alves, LuísABSTRACT: Many of the new generation fuels, although more sustainable, share some of the problems inherent to fossil fuels. Depending on the biomass/material that originated them, they can present different contaminants that can lead to environmental problems. Sulfur is one of the most common and problematic contaminants in fuels. It is released into the atmosphere in the form of SOx, leading to the formation of acid rains, which cause drastic environmental and infrastructural problems, as well as several types of health issues. High sulfur concentrations in fuels also result in a loss of efficiency of motors and energy generation systems, mostly due to corrosion and catalyst poisoning. The current thermochemical desulfurization process, hydrodesulfurization (HDS), is energy demanding, pollutant and has low efficiency against more complex organosulfur molecules. This led researchers to look for new alternatives. Biodesulfurization (BDS), is, as the name implies, the biological removal of sulfur from fuels using microorganisms as living biocatalysts. If correctly employed this process could be more efficient and less pollutant, since microorganisms directly target the sulfur atoms, even those present in complex molecular structures, such as dibenzothiophene (DBT). Moreover, microbial activity occurs at much lower temperatures and pressures, without the need for metal catalysts, resulting in a lower energy demand. While BDS is a promising technology, it is still at a low development stage, mostly due to some bottlenecks, which have been hindering its large-scale application. Similarly, to other biotechnological processes, it presents lower reaction rates, when compared to HDS, since it depends on the use of living organisms as catalysts. Furthermore, it must be performed under conditions that allow the microorganisms to maintain biological activity, limiting the range of applications. These conditions vary greatly depending on the microorganism selected, and their optimization can significantly increase the biodesulfurization activity of a biocatalyst.
- The CONVERTE project: biomass potential for energyPublication . Abreu, Mariana; Moura, Patrícia; Reis, Alberto; Eusebio, Ana; Oliveira, Ana Cristina; Pinto, Filomena; Alexandre, Jorge; Silva, Luís; Trancoso, Maria Ascensão; Gírio, FranciscoABSTRACT: Climate change caused by the excessive use of non-renewable resources as a means of supporting the current society demands is forcing the development of circular economy models and social, economic and environmental balanced solutions. In Portugal, in recent decades, important progresses have been made on waste resources management practices in line with the objectives and directives of the European Union. The urban and industrial wastes are, to a certain extent, a case of success since the effort developed has created tools for the prevention, control, recovery and recycling of a considerable percentage of the generated amounts. However, this effort has not yet reached its full potential, and there are still diverse underexplored issues, such as a systematic assessment of the waste biomass suitability for specific energy conversion technologies, and the promotion of non-food-competing energy crops on marginal lands. CONVERTE will identify and quantify the different waste biomass types generated in the Portuguese continental territory, and shall develop a biomass-driven energy matrix that correlates the biomass types with eight technological value chains for heat, power and/or advanced biofuels as main products. This is expected to impact positively on the national energy security and to reduce the overall Portuguese greenhouse gas (GHG) emissions, namely in the transport sector, contributing to increase the country sustainability score.
- Metal soption and partitioning coefficients in all matrices of the Torres Vedras SBR WWTP, Portugal [Resumo]Publication . Cantinho, P.; Santos, M. M. Correia dos; Trancoso, Maria Ascensão; Cortês, E.; Matos, M.ABSTRACT: The literature review concerning the issue of metals behaviour and fate throughout WWTPs shows that, although relevant data have been published in recent decades, results are not consensual and more studies are needed, particulary from data obtained in full scale WWTPs.
- Metal concentrations and removal along the SBR wastewater treatment plant of Torres Vedras, Portugal [Resumo]Publication . Cantinho, P.; Santos, M. M. Correia dos; Trancoso, Maria Ascensão; Cortês, E.; Matos, M.ABSTRACT: The concerns on metals in municipal Wastewater Treatment Plants (WWWTPs) discharges are mainly related with its contents in sludge, witch can prevent its application in land and so the recycling of valuable nutrients, and with the more restrictive limits foreseen for final effluents, due to the recent guidelines introduced by European Water Framework Directive (EUWFD).