1,721,012 research outputs found
Biodiesel e microalghe: energia per un futuro sostenibile
No full textThe competitive potential of biodiesel is limited by the price of vegetable oils and production
process, which strongly influences the final price. An appropriate planning and design of the whole production process, and the utilisation of dedicated crops; are essential in order to contain the
high price of the end product. The purposes of this dissertation are to optimize the conversion of vegetables oil to biodiesel and identify a possible alternative of food crops. the is to measure the
phase equilibria and then identify the thermodynamic model that best fit the experimental data obtained. Then a real biodiesel process is optimized. The optimisation of reaction and separation
steps need the measurements of the phase equilibria of the of the systems involved during the production of biodiesel. Once the defined the thermodynamic model that best fit the experimental
results, a multi-objective optimization of a real process performed. The objective of the optimisation are the minimisation of energy consumption and the maximisation of biodiesel quality. A possible
alternative to food crops, like raw material for lipids, are Microalgae. Microalgae have a large biotechnological potential for production of a variety of compounds such as polysaccharides, lipids, proteins, carotenoids, pigments, vitamins, steroids, pharmaceuticals, and other fine chemicals, as
well as hydrogen, hydrocarbons, and biofuels. They are organisms that can convert solar energy into biomass with high efficiency and yield. In addition, microalgae appear more photosynthetically
efficient than terrestrial plants and are the candidates as the best efficient carbon dioxide fixers to reduce greenhouse emissions
Effects of rapid acidification in marine seawater: Focus on Actinopterygii
No full textThe progressive acidification of the world's oceans has led to widespread concern regarding the potential consequences for marine biosphere. As a result, most research has been focused on the steady increase of dissolved CO2 and consequent acidification thus on calcifying species while less attention has been paid to the physiological and developmental impacts of teleost fish. However, rapid and massive release of carbon dioxide (CO2) into the marine environment may occur due to both natural and anthropogenic causes. This review specifically examines the outcomes of rapid but confined CO2 emissions, with a focus on their role in accelerating the local acidification of seawater and on the related effects on Actinopterygii. It examines the impacts of elevated CO2 levels on marine fishes, also emphasizing the lack of experimental evidence on embryonic larval and larval phases, which are highly vulnerable to acid-base imbalances and related physiological disruptions. A broad review of literature published between 1963 and 2025, on fishes' exposure to varying CO2 conditions, highlights pronounced variability in responses across species and developmental stages. Early life phases frequently exhibit reduced survival, skeletal and sensory anomalies, and shifts in metabolic demand. Although some taxa demonstrate compensatory adjustments, the resulting energetic costs and physiological trade-offs can limit growth, reproduction, and long-term resilience. Advancing our understanding of fish vulnerability and adaptive potential under seawater acidification of marine fishes in an acidifying environment requires long-term, ecologically relevant designs and integrated approaches that link multiple life stages and biological scales
Novel characterisation of biofuel-integrated phytoremediation of liquid wastes with Scenedesmus obliquus
No full textThis study investigates the feasibility of in situ phytoremediation of leachate and wastewater in municipal solid waste facilities using microalgae and their valorisation for biofuel production. Laboratory-scale experiments were conducted by cultivating the Scenedesmus obliquus microalga in a diluted growth medium inside a 4 L indoor photobioreactor, operating in batch mode. Volumetric productivity data were employed to evaluate the economic viability of the system. Then, a numerical model developed in Aspen Plus was used to estimate the utility requirements for upgrading crude microalgae oil into biodiesel meeting commercial specifications. The results indicate that, although the resulting biodiesel satisfies UNI EN 14214 quality standards, the limited biomass productivity remains a critical constraint for economic feasibility. Remuneration, in terms of net present value is achievable only under scenarios that combine high biomass yield and microalgae oil sale prices exceeding 2–2.5 € kg−1. The system generates 57–722 k€ after 20 years
Screening for tolerance to natural phenols of different algal species: Toward the phycoremediation of olive mill wastewater
No full textOlive Mill Wastewater (OMWW) is a by-product of olive oil production and it is rich in nutrients (e.g. P, N and K) and phenolic compounds. These latter are aromatic compounds, and their concentrations can reach up to 11 g L−1 in OMWW. A complete remediation of OMWW is required since phenols are known to cause toxicity once released in the environment: particularly, their effect on microorganisms is species-specific and primarily depends on the chemical structure of the compound. Microalgae have already been tested to remediate OMWW, data are promising but how different phenols affect algal growth is still poorly known. In this work, ten microalgal species belonging to different phylogenetic groups and natural habitats, were grown in the presence of three phenolic compounds found in OMWW (tyrosol, coumaric acid, caffeic acid). Algal growth and removal of phenolic compounds were assessed. Tyrosol was the only compound allowing growth of each tested microalga similarly to what observed in control media. Growth of microalgae and removal of phenolic compounds were not always related, and a multi-step phenolic removal mechanism was suggested. Species such as Nannochloropsis salina and Porphyridium purpureum rapidly died after the addition of coumaric acid or caffeic acid but a high removal percentage (60–100 %) of the phenols was still observed and it was likely due to their absorbance onto the cell surface. On average, freshwater species showed a higher growth performance compared to the one of marine species; in particular, Tetradesmus obliquus and Anabaena sp. showed the best results. This work elucidates a species-specific effect for each phenolic compound on algal growth and it also highlights that growth and removal are not related phenomena
Principio degli stati corrispondenti per il calcolo della tensione superficiale di refrigeranti
No full textPROGETTAZIONE E REALIZZAZIONE DI UNA MACCHINA FRIGORIFERA AD ENERGIA SOLARE PER LA CONSERVAZIONE DEI VACCINI O DELLE DERRATE ALIMENTARI
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