Browsing by Issue Date, starting with "2018"
Now showing 1 - 10 of 133
Results Per Page
Sort Options
- Scenedesmus obliquus in poultry wastewater bioremediationPublication . Oliveira, Ana Cristina; Barata, Ana; Batista, Ana Paula; Gouveia, LuisaABSTRACT: Wastewater biological treatment with microalgae can be an effective technology, removing nutrients and other contaminants while reducing chemical oxygen demand. This can be particularly interesting for the meat producing industry which produces large volumes of wastewater from the slaughtering of animals and cleaning of their facilities. The main purpose of this research was the treatment of poultry wastewater using Scenedesmus obliquus in an economical and environmentally sustainable way. Two wastewaters were collected from a Portuguese poultry slaughterhouse (poultry raw - PR and poultry flocculated - PF) and the bioremediation was evaluated. The performance of microalga biomass growth and biochemical composition were assessed for two illumination sources (fluorescent vs LEDs). S. obliquus achieved positive results when grown in highly contaminated agro-industrial wastewater from the poultry industry, independently of the light source. The wastewater bioremediation revealed results higher than 97% for both ammonium and phosphate removal efficiency, for a cultivation time of 13 days. The saponifiable matter obtained from the biomass of the microalga cultures was, on average, 11% and 27% (m/malga) with PR and PF wastewater, respectively. In opposition, higher sugar content was obtained from microalgae biomass grown in PR wastewater (average 34% m/malga) in comparison to PF wastewater (average 23% m/malga), independently of the illumination source. Therefore, biomass obtained with PR wastewater will be more appropriate as a raw material for bioethanol/biohydrogen production (higher sugar content) while biomass produced in PF wastewater will have a similar potential as feedstock for both biodiesel and bioethanol/biohydrogen production (similar lipid and sugar content).
- Co-liquefaction of wastes and coal mixtures to produce added value liquid compoundsPublication . Pinto, Filomena; Costa, Paula; Paradela, Filipe; Silva, Pedro; Meredith, Will; Stevens, Lee; Snape, ColinABSTRACT: Nowadays there is an increasing need to find alternative fuels to reduce the dependency on imported ones and to decrease the negative environmental impact of wastes accumulation. Plastics are an important components of urban biowaste, thus their conversion into liquid fuels, in mixtures with other solid fuels still remains an important research goal. After the large experience obtained from coal gasification, it was found that co-liquefaction of coal and wastes may be a good solution to produce liquid fuels and raw materials for several industries. Co-liquefaction of coal blended with biomass gave unfavourable results, but co-liquefaction of coal mixed with PE (polyethylene) wastes led to encouraging results. The results obtained showed that the rise of PE content in coal blends led to an increase in liquid yield. As the main objective was the formation of liquid products, the mixture of coal with 50 wt% of PE was selected, as substantial total liquid yields were obtained, while using significant coal content. This blend was used to study the effect of initial hydrogen pressure, reaction temperature and time on products yields, using Response Surface Methodology (RSM) approach. Liquid yields were most affected by reaction temperature and pressure. The rise of temperature decreased liquid yields, while pressure had a positive effect, but the interaction between these two parameters showed a negative influence. Theoretical equations were used to calculate total and direct liquids yield (%daf). Total liquids are the sum of the liquids directly recovered from the autoclave (direct liquids) and the liquids extracted from the solid product. Both the theoretical model and the experimental results showed that the highest total liquids yields were obtained at 380 ºC, 1.4 MPa and 90 minutes.
- Fermentative hydrogen production from microalgal biomass by a single strain of bacterium Enterobacter aerogenes: effect of operational conditions and fermentation kineticsPublication . Batista, Ana Paula; Gouveia, Luisa; Marques, PaulaABSTRACT: Biohydrogen production through dark fermentation is a promising technology for generating renewable energy, while using microalgal biomass as a third generation feedstock can further increase the sustainability of the process. In the present study, Scenedesmus obliquus was used as model microalga substrate for studying the impact of operational parameters in batch dark fermentation trials using a strain of Enterobacter aerogenes bacteria. (i) The initial gas-liquid ratio in the bioreactor (from 13 to 8.2) was tested, resulting in higher bioH(2) yields for ratios above 5. (ii) Different bacterial growth, inoculation procedures and fermentation media were tested in combined experiments. The best conditions were chosen by maximising bioH(2) yield and minimising production time and costs. (iii) The autoclave sterilization effect on sugar extraction and bioH(2) yield was tested for different microalga concentrations (2.5-50 g/L) with best results attained for 2.5 g/L (81.2% extraction yield, 40.9 mL H-2/g alga). For the best operational conditions, fermentation kinetics were monitored and adjusted to the Modified Gompertz model, with t(95) (time required for bioH(2) production to attain 95% of the maximum yield) below 4.5 h. The maximum hydrogen production was higher when using wet algal biomass enabling the energy Consuming biomass drying step to be skipped.
- 3DOM ceria ecoceramics from sustainable cork templates for solar thermochemical CO2 splittingPublication . Pullar, Robert C.; Novais, Rui M.; Caetano, Ana P. F.; Barreiros, M. Alexandra; Abanades, Stéphane; Almeida Costa Oliveira, Fernando
- Anaerobic digestion of pre-treated microalgae biomass [Resumo]Publication . Neves, André; Silva, Teresa Lopes da; Reis, Alberto; Ramalho, Luís; Eusebio, Ana; Marques, Isabel Paula
- Microalgae-mediated brewery wastewater treatment: effect of dilution rate on nutrient removal rates, biomass biochemical composition, and cell physiologyPublication . Marchão, Leonilde; Silva, Teresa Lopes da; Gouveia, Luisa; Reis, AlbertoABSTRACT: Microalgae have been used to remove nitrogen, phosphorus, and chemical oxygen demand (COD) from brewery wastewater (BWW). The microalga Scenedesmus obliquus was grown on BWW, using bubble column photobioreactors that operated under batch and continuous regimes. For the first time, the cell physiological status cell membrane integrity and enzymatic activity was monitored during the microalgae based BWW treatment, using flow cytometry. All the cultivations batch and continuous displayed a proportion of cells with intact membrane > 87%, although the continuous cultivations displayed a lower proportion of cells with enzymatic activity (20-40%) than the batch cultivations (97%). The dilution rate of 0.26 day(-1) was the most favorable condition, since the microalgae cultivation attained the maximum biomass productivity (0.2 g ash-free dry weight day(-1)) and the total nitrogen and COD removal rates were the highest (97 and 74%, respectively), while the phosphorous removal rate was the third (23%).
- Biotechnology of polysaccharides for biofuels and bio-based products [Comunicação oral]Publication . Gírio, Francisco
- Co-evolutionary dynamics of policy and system development : the case of marine renewable energy technologiesPublication . Fontes, Margarida; Karadzic, Vanja; Pereira, Tiago Santos; Bento, NunoABSTRACT: The transition to a sustainable energy system is a major societal challenge requiring profound trans-formations in existing socio-technical systems (Markard et al, 2012). These processes have been addressed by the sociotechnical transitions literature that called the attention to the role played by radically new technologies, being developed in niches, which have strong transformative potential (Kemp et al, 1998; Schot and Geels, 2007). These technologies and the socio-technical systems de-veloping around them often need temporary protection against the selection pressures of the estab-lished regimes (Smith and Raven, 2016); and supportive policies are a fundamental mode of protec-tion (Kivimaa and Kern, 2016). In the case of sustainable energy technologies, policy support is fur-ther justified by the need to accelerate the transition process (which is usually a long term process), given the urgency of fighting against climate change (IPCC, 2014).
- Protein profiling as early detection biomarkers for TiO2 nanoparticle toxicity in Daphnia magnaPublication . Sá-Pereira, Paula; Diniz, Mário S.; Moita, Liliana; Pinheiro, Teresa; Mendonça, E.; Paixão, Susana M.; Picado, AnaABSTRACT: The mode of action for nanoparticle (NP) toxicity in aquatic organisms is not yet fully understood. In this work, a strategy other than toxicity testing was applied to Daphnia magna exposed to TiO2-NPs: the use of nuclear microscopy and the assessment of protein profile. D. magna is a keystone species broadly used as a model system in ecotoxicology. Titanium (Ti) was found in the D. magna digestive tract, mainly in the gut. The penetration of Ti into the epithelial region was greater at higher exposure levels and also observed in eggs in the brood pouch. The protein profile of individuals exposed to different concentrations showed that 2.8 and 5.6 mg/L TiO2-NP concentrations induced an over-expression of the majority of proteins, in particular proteins with molecular weight of similar to 120, 85 and 15 kDa, while 11.2 mg/L TiO2-NP had an inhibitory effect on protein expression. The Matrix-assisted laser desorption ionization with tandem time of flight mass spectrometry (MALDI-TOF/TOF MS) analysis of these proteins consistently identified them as vitellogenin (Vtg)-like proteins, associated with enzymes involved in redox balance. These results indicate that Vtg-like proteins are up-regulated in D. magna exposed to TiO2-NPs. Vitellogenesis is associated with the reproduction system, suggesting that TiO2-NP exposure can impair reproduction by affecting this process. The precise mode of action of TiO2-NPs is still unclear and the results from this study are a first attempt to identify specific proteins as potential markers of TiO2-NP toxicity in D. magna, providing useful information for future research.
- Biorefineries in Europe (and World) [Comunicação oral]Publication . Gírio, Francisco