Bioenergia - UB
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- 13 anos de monitorização da descarga do emissário submarino da Guia: integração na DQAPublication . Santos, C.; Catarino, Justina; Barreiros, M. Alexandra; Trancoso, Maria Ascensão; Marques, Eugénia; Garcia, Carla; Neves, Ramiro; Carvalho, Vânia; Lopes, CatarinaO Programa das Nações Unidas para o Ambiente define monitorização como “o processo de observação repetitivo com fins definidos, de um ou mais elementos do ambiente, de acordo com um planeamento prévio no espaço e no tempo, utilizando metodologias comparáveis para caracterização ambiental e colheita de dados”. A Directiva Quadro da Água (DQA), o instrumento orientador na União Europeia para gestão das águas superficiais interiores, águas de transição, águas costeiras e águas subterrâneas, suporta este conceito propondo, no entanto, três níveis para os programas de monitorização: (1) monitorização de vigilância orientada para a evolução a longo prazo; (2) operacional, orientada para zonas em risco de não atingir os objectivos de qualidade requeridos pela DQA; (3) de investigação orientada para a compreensão e quantificação dos processos responsáveis por excessos que levam ao incumprimento da DQA. Embora sejam os Estados-Membros quem devam adoptar estas medidas e cumprir os seus objectivos, o comportamento pró-activo de algumas empresas contribui significativamente para o cumprimento das exigências da DQA. A SANEST, Saneamento da Costa do Estoril, empresa gestora do Sistema de Saneamento da Costa do Estoril implementou um programa de monitorização da descarga do emissário submarino da Guia. Este programa deu continuidade ao iniciado em 1993, antes da entrada em funcionamento do sistema, e é o maior programa de monitorização a nível nacional em zonas costeiras, que inclui investigação detalhada a vários níveis. O progressivo aumento do número de parâmetros e a adaptação de metodologias, quer na ETAR quer no meio receptor, demonstra também a preocupação desta empresa pela salvaguarda e gestão sustentável dos recursos. Neste trabalho são apresentados os principais resultados do programa de monitorização referido, levado a cabo por Laboratórios de Estado e Universidades portugueses, que em conjunto cobrem os requisitos normativos nacionais e internacionais, em termos analíticos, e detêm o conhecimento necessário à componente de monitorização operacional, preconizada na DQA.
- Ability of Gordonia alkanivorans strain 1B for enhanced desulfurization of dibenzothiophene and its derivatives using fructose as carbon sourcePublication . Alves, Luís; Silva, Tiago; Fernandes, A. S.; Paixão, Susana M.In order to keep up the strict sulfur limits on fossil fuels and their derivatives, refineries commonly use a desulfurization method, which combines high temperatures and pressures with molecular hydrogen known as hydrodesulfurization (HDS). However, the effectiveness of HDS to desulfurize recalcitrant organic aromatic compounds such as dibenzothiophene (DBT) or its derivatives is low. Biodesulfurization (BDS) has been described as a promising complementary technique to HDS. Using microorganisms, BDS is able of desulfurize several recalcitrant compounds usually present in fossil fuels at mild temperatures and pressures without hydrogen, making it a simple and eco-friendly process. In this context and based in the fructophilic behavior of the desulfurizing bacterium, Gordonia alkanivorans strain 1B, several recalcitrant sulfur sources were tested in BDS assays using fructose as carbon source. So, strain 1B was used in desulfurization assays testing 4-mDBT, 4,6-dmDBT and 4,6-deDBT, as sulfur source, in comparison with DBT. Growth and desulfurization kinetics using the different sulfur sources were evaluated and the desulfurization rates were determined by GC analysis of x-DBT consumed. The results showed that the strain 1B using fructose as carbon source was able to fully desulfurize all the sulfur compounds tested in less than 121 hours. For 4-mDBT, 4,6-dmDBT and 4,6-deDBT the maximal bacterial growth rates obtained were 0.072 h-1, 0.069 h-1 and 0.095 h-1 with maximum desulfurization rates of 1.58, 4.84 and 4.30 umol g(DCW)-1 h-1, respectively. In comparison with previous results obtained for max of strain 1B in glucose as carbon source and DBT as sulfur source (0.025 h-1), all the m_ max obtained in this study highlight once more the importance of use fructose as carbon source, independently of sulfur source. In addition, contrary to what has been described for other strains, the desulfurization rates obtained for the compounds with two alkyl groups were higher than for DBT (2.12 umol g(DCW)-1 h-1). In fructose, the desulfurization of 4,6-dmDBT and 4,6-deDBT by strain 1B were more than 2-fold in comparison with that for DBT. These promising results indicate the high potential of use this bacterium towards fossil fuels BDS.
- Ability of Gordonia alkanivorans strain 1B for high added value carotenoids productionPublication . Silva, Tiago; Paixão, Susana M.; Alves, LuísCurrently, carotenoids are valuable bioactive molecules for several industries, such as chemical, pharmaceutical, food and cosmetics, due to their multiple benefits as natural colorants, antioxidants and vitamin precursors. Hence, the increasing interest on these high added-value products has led to the search of alternatives, more cost-effective and with better yields, towards their industrial production. Indeed, microbial metabolism offers a promising option for carotenoids production. Herein it is shown the potential of the dibenzothiophene desulfurizing bacterium Gordonia alkanivorans strain 1B as a high carotenoid-producer microorganism. The novel carotenoids, produced under different culture conditions, were extracted with DMSO and then further analyzed both through spectrophotometry and HPLC. When grown in glucose-sulfate-light, strain 1B was able of achieving 2015 g carotenoids per g DCW in shake-flask assays, with about 60% corresponding to lutein, canthaxanthin and astaxanthin. Further optimization studies open a new focus of research aiming to get a hyper pigment-producer strain that may be applied towards different industrial sectors.
- Acid-modified clays as green catalysts for the hydrolysis of hemicellulosic oligosaccharidesPublication . Vilcocq, Léa; Spinola, Vitor; Moniz, Patricia; Duarte, Luís C.; Carvalheiro, Florbela; Fernandes, César; Castilho, Paula C.The hydrolysis of hemicellulosic oligosaccharides (OS) was investigated using acid-activated clays (prepared from natural Porto Santo montmorillonite clay) as catalysts. Acid activation was performed in HCl solution or with aluminium exchange. The clay catalysts were characterized by XRD, N2 adsorption isotherms, CEC, FTIR, titration of acid sites in water and adsorption of sugars and disaccharides. They were tested for the hydrolysis of a model compound, maltose, and of OS-rich liquor from rice straw fractionation. The HCl-activated clays were the most efficient catalysts for maltose hydrolysis. It was demonstrated that the hydrolysis of OS into monomer sugars over a clay catalyst is technically feasible and that this reaction leads to the selective removal of glucose, arabinose and acetic acid side groups from the OS structure, thus yielding simpler xylo-oligosaccharide chains. Furthermore, no significant conversion of monomer sugars into furans was observed.
- Acidic ionic liquids as sustainable approach of cellulose and lignocellulosic biomass conversion without additional catalystsPublication . Lopes, André; Lukasik, Rafal M.The use of ionic liquids (ILs) for biomass processing has attracted considerable attention recently as it provides distinct features for pre-treated biomass and fractionated materials in comparison to conventional processes. Process intensification through integration of dissolution, fractionation, hydrolysis and/or conversion in one pot should be accomplished to maximise economic and technological feasibility. The possibility of using alternative ILs capable not only of dissolving and deconstructing selectively biomass but also of catalysing reactions simultaneously are a potential solution of this problem. In this Review a critical overview of the state of the art and perspectives of the hydrolysis and conversion of cellulose and lignocellulosic biomass using acidic ILs using no additional catalyst are provided. The efficiency of the process is mainly considered with regard to the hydrolysis and conversion yields obtained and the selectivity of each reaction. The process conditions can be easily tuned to obtain sugars and/or platform chemicals, such as furans and organic acids. On the other hand, product recovery from the IL and its purity are the main challenges for the acceptance of this technology as a feasible alternative to conventional processes.
- Activated carbons from the co-pyrolysis of rice wastes for Cr(III) removalPublication . Dias, Diogo; Bernardo, Maria; Lapa, Nuno; Pinto, Filomena; Matos, Inês; Fonseca, Isabel MariaABSTRACT: Rice husk and polyethylene were mixed (50 % w/w each) and submitted to a pyrolysis assay. Four physical activations with CO2 were performed on the resulting co-pyrolysis char (PC). The activation at 800 °C, for 4h, generated the activated carbon (PAC3) with the best textural properties. PC, PAC3 and a commercial activated carbon (CAC) were characterized and submitted to Cr(III) removal assays. PC had a high percentage of volatile matter that was removed after the physical activation, resulting in more available pores in the final material (PAC). In the Cr(III) removal assays, two S/L ratios were tested: 5 and 10 g L-1. PC did not remove any Cr(III) from the solutions, but PAC presented similar results to CAC. At the S/L of 5 g L-1, Cr(III) removal was of 58.5 % for PAC and 62.5 % for CAC, both by adsorption mechanism; at the S/L of 10 g L-1, Cr(III) removal was almost complete due to precipitation caused by pH increase. The highest uptake capacities were of 7.92 mg g-1 for PAC and 8.71 mg g-1 for CAC, at the S/L of 5 g L-1. The results indicated that PAC3 may be a viable alternative to CAC on Cr(III) removal from aqueous media.
- Acute toxicity evaluation of several compounds involved in fossil fuels biodesulphurisation studiesPublication . Alves, Luís; Paixão, Susana M.; Gírio, FranciscoThe increasing use of fossil fuels has led to increased emissions of sulphur oxides into the air, which is a major cause of acid rain. Legislation already adopted in 2009 stipulates that the maximum level of sulphur allowed in fuels is only 10 ppm. The process of hydrodesulphurization (HDS) used in refineries is based on very expensive physico-chemical techniques, and has limitations in the removal of organic sulphur. As for stricter legislation on the maximum levels of sulphur in fossil fuels, the most HDS recalcitrant compounds needs to be removed. This implies an increase in the intensity of the physical-chemical treatment and inherently its associated costs. As a result, the recalcitrant compounds to HDS represent a significant barrier to the achievement of very low levels of sulphur in some petroleum fractions. The alternative to the physical-chemical treatment could be the use of biological processes (biodesulphurisation) which is more effective for the desulphurization of fossil fuels, especially as the removal of sulphur covalently bound to organic matrices. The biodesulphurisation (BDS) occurs in more mild conditions of operation under conditions of atmospheric pressure and temperature, giving greater specificity of reaction due to the nature of the biocatalysts, not requiring molecular hydrogen. Thus, in the last 15 years there has been an increase of studies involving the use of microorganisms with the ability to specifically remove the HDS recalcitrant sulphur compounds. Several model compounds such as dibenzothiophene (DBT), DBT sulphone or benzothiophene (BT) are used in BDS studies to characterise organic sulphur in coal, coal tars and crude oils. The desulphurising microorganisms are able to remove the sulphur atom from these compounds and use it in their metabolism. However, such compounds are very toxic to the cells. The aim of this work was to evaluate the toxicity of several compounds used in BDS studies, such as DBT and its derivatives and organic solvents used to dissolve these hydrocarbons, to two typical desulphurising strains, namely: Gordonia alkanivorans strain 1B and Rhodococcus eritropolis strain D1. The toxicity bioassays evaluated the inhibitory effect of the studied compounds to the described bacteria by measuring the respiration rate (mg O2/l) under defined conditions in the presence of different concentrations of those compounds. The inhibitory or toxic effect of each chemical at a specific concentration is expressed as a percent of the baseline respiration rate. From these results the several IC50s were estimated and are described in Table 1. These toxicity values showed that strain 1B was less sensitive for almost all of the hydrocarbons, which is an important advantage considering the desulphurisation of fossil fuels process. On the other hand, strain 1B was more sensitive to dimethylformamide (DMF), a typical solvent used in BDS studies. However, a good correlation can be observed between IC50-1B versus IC50-D1 (IC50-D1 = 0.504 x IC50-1B + 2.84; r2 = 0.908, p < 0.05).
- Admissibility Grid to Support the Decision for the Preferential Routing of Portuguese Endogenous Waste Biomass for the Production of Biogas, Advanced Biofuels, Electricity and HeatPublication . Crujeira, Teresa; Trancoso, Maria Ascensão; Eusebio, Ana; Oliveira, Ana Cristina; Passarinho, Paula; Abreu, Mariana; Marques, Isabel Paula; Marques, Paula; Marques, Susana; Albergaria, Helena; Pinto, Filomena; Costa, Paula; Andre, Rui N.; Girio, Francisco; Moura, PatríciaABSTRACT: A methodology was developed to assess the allocation of different types of endogenous waste biomass to eight technologies for producing electricity, heat, biogas and advanced biofuels. It was based on the identification of key physicochemical parameters for each conversion process and the definition of limit values for each parameter, applied to two different matrices of waste biomass. This enabled the creation of one Admissibility Grid with target values per type of waste biomass and conversion technology, applicable to a decision process in the routing to energy production. The construction of the grid was based on the evaluation of 24 types of waste biomass, corresponding to 48 sets of samples tested, for which a detailed physicochemical characterization and an admissibility assessment were made. The samples were collected from Municipal Solid Waste treatment facilities, sewage sludges, agro-industrial companies, poultry farms, and pulp and paper industries. The conversion technologies and energy products considered were (trans)esterification to fatty acid methyl esters, anaerobic digestion to methane, fermentation to bioethanol, dark fermentation to biohydrogen, combustion to electricity and heat, gasification to syngas, and pyrolysis and hydrothermal liquefaction to bio-oils. The validation of the Admissibility Grid was based on the determination of conversion rates and product yields over 23 case studies that were selected according to the best combinations of waste biomass type versus technological solution and energy product.
- Advances in the reduction of the costs inherent to fossil fuel biodesulfurization towards its potential industrial applicationsPublication . Paixão, Susana M.; Silva, Tiago; Arez, B. F.; Alves, LuísABSTRACT: The biodesulfurization (BDS) process consists of the use of microorganisms for the removal of sulfur from fossil fuels. Through BDS it is possible to treat most of the organosulfur compounds recalcitrant to the conventional hydrodesulfurization (HDS), the petroleum industry's solution, at mild operating conditions, without the need for molecular hydrogen or metal catalysts. This technique results in lower emissions, smaller residue production, and less energy consumption, which makes BDS an eco-friendly process that can complement HDS making it more efficient. BDS has been extensively studied and much is already known about the process. Clearly, BDS presents advantages as a complementary technique to HDS; however, its commercial use has been delayed by several limitations both upstream and downstream the process. This study will comprehensively review and discuss key issues, like reduction of the BDS costs, advances, and/or challenges for a competitive BDS towards its potential industrial application aiming ultra-low sulfur fuels.
- Advances in the reduction of the costs inherent to fossil fuel biodesulfurization towards its potential industrial applicationsPublication . Paixão, Susana M.; Silva, Tiago; Arez, B. F.; Alves, LuísABSTRACT: The biodesulfurization (BDS) process consists of the use of microorganisms for the removal of sulfur from fossil fuels. Through BDS it is possible to treat most of the organosulfur compounds recalcitrant to the conventional hydrodesulfurization (HDS), the petroleum industry's solution, at mild operating conditions, without the need for molecular hydrogen or metal catalysts. This technique results in lower emissions, smaller residue production, and less energy consumption, which makes BDS an eco-friendly process that can complement HDS making it more efficient. BDS has been extensively studied and much is already known about the process. Clearly, BDS presents advantages as a complementary technique to HDS; however, its commercial use has been delayed by several limitations both upstream and downstream the process. This study will comprehensively review and discuss key issues, like reduction of the BDS costs, advances, and/or challenges for a competitive BDS towards its potential industrial application aiming ultra-low sulfur fuels.