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Microbial sludge formation in Brazilian marine diesel oil (B0) and soybean methylic biodiesel blends (B10 and B20) during simulated storage
(2022) Silva, Thais Livramento; Cazarolli, Juciana Clarice; Pizzolato, Tânia Mara; Frazzon, Ana Paula Guedes; Mann, Michele Bertoni; Frazzon, Jeverson; John, Danielle Kochenborger; Ferrão, Marco Flôres; Rampelotto, Pabulo Henrique; D'Alessandro, Emmanuel Bezerra; Antoniosi Filho, Nelson Roberto; Bento, Fatima Menezes
Biofuels are renewable alternatives to fossil fuels mainly due to the lower impact they have in terms of release of air pollutants. Brazilian diesel oil must be composed of 10–15% biodiesel, while the addition of biodiesel to marine diesel oil has not yet been authorized. This paper aimed to evaluate the impact of the addition of biodiesel to marine diesel oil. The biotic and abiotic degradation of pure (B0) marine diesel oil and that with the addition of 10% (B10) and 20% (B20) of soybean methyl biodiesel were evaluated in simulated storage in an aqueous phase of Bushnell Haas mineral medium for 28 days. An uncharacterized inoculum (adapted from the ASTM E1259-16 standard) was prepared from a microbial population found in the marine diesel oil storage tank of a ship. For 28 days, microbial growth was monitored by gravimetry and the composition of the fungal microbial community was determined by next-generation sequencing (NGS). In the aqueous phase of the tests, the nature of the metabolites (pH measurements, headspace-solid phase microextraction [HS-SPME], gas chromatography with mass spectrometry (GC–MS), detection of the lipase enzyme (Rhodamine B Medium) and production of biosurfactants (surface tension measurements) were assessed. The oil phase was evaluated by gas chromatography (GC) and infrared spectroscopy. Higher biomass was observed in the B20 condition and the microbial community analysis revealed the dominance of the genus Pseudallescheria. No significant pH decreases were observed in the aqueous phase; however, the analyses by HS-SPME and GC–MS showed the presence of organic acids, alkanes, and phenols in both conditions, with and without microorganisms. The infrared results with the mixtures (10 and 20%) showed degradation of the biodiesel fraction. GC analysis showed that the linoleic acid methyl ester was the most susceptible to degradation by microorganisms. Thus, the results found showed the impact of adding biodiesel to marine diesel, calling attention to the need for maintenance routines, which will guarantee the final quality of the stored fuel.
Effect of different cultivation conditions on the production of volatile organic compounds by the microalgae Arthrospira platensis and Chlorella sp.
(2022-01-03) Nader, Camila; Cella, Herculano; Lopes, Rafael Garcia; Oliveira, Carlos Yure Barbosa de; D'Alessandro, Emmanuel Bezerra; Antoniosi Filho, Nelson Roberto; Derner, Roberto Bianchini
Volatile organic compounds (VOCs) from microalgae have many applications in several industries, and their synthesis can be affected by several factors, such as light and growth phase. Thus, this study aimed to determine the influence of different irradiances and growth phases on the VOC profile of Arthrospira platensis and Chlorella sp. Biomasses of cultures subjected to 200 and 1000 µmol photons m−2 s−1 and harvested in the exponential and stationary growth phases were analyzed by gas chromatography and mass spectrometry. Twelve VOCs were found in the biomasses of A. platensis and 34 in the biomasses of Chlorella sp., with only five compounds in common for both species. In the biomasses of A. platensis, many hydrocarbons were found, being this class the one with the greatest representative in this species VOC profile. Octadecane, which may have several applications in the food industry, was the predominant compound, showing high values under 1000 µmol photons m−2 s−1 in the stationary growth phase. On the other hand, in Chlorella sp. biomasses, a variety of nitrogenous compounds was found, and octadecyl vinyl ether had the highest values under 200 µmol photons m−2 s−1 in the stationary phase. A couple of terpenoids were found in both microalgae, except safranal, which was only detected in Chlorella sp. In conclusion, the results confirm that both the irradiance and growth phase influenced the VOC profile of A. platensis and Chlorella sp. as changes in the percentage and types of VOCs present in each species were observed in the cultivation conditions evaluated.
A comparison of harvesting and drying methodologies on fatty acids composition of the green microalga Scenedesmus obliquus
(2020) Oliveira, Carlos Yure Barbosa de; Lopes, Rafael Garcia; Cella, Herculano; Menezes, Rafael Silva; Soares, Aline Terra; Antoniosi Filho, Nelson Roberto; Derner, Roberto Bianchini; Freitas, Thayna Lye Viegas
Harvesting and drying processes are still obstacles in the microalgae production chain. In this study, a combination of different harvesting and drying methods for Scenedesmus obliquus was proposed. S. obliquus was cultivated in a pond raceway for 15 days until reaching stationary phase. The culture was separated by different harvesting methods (centrifugation and flocculation) and drying methods (freezing, freeze-drying and oven drying), each combination in triplicate. Flocculation did not influence FAME yield of S. obliquus, except when the biomass was dried in an oven. The biomass that was only frozen had the lowest FAME content due to the presence of reactive water in the biomass. In contrast, frozen biomass had higher content of saturated and monosaturated fatty acids; freeze-drying or oven drying caused an enrichment of the polyunsaturated fatty acids content. In conclusion, if the biomass will be used to extract polyunsaturated fatty acids, freeze-drying would be more appropriate. On the other hand, if the purpose of the biomass is to produce biodiesel, the best process would be to just freeze the biomass.
Renewable source hydrocarbons obtaining from microalgae by catalytic deoxygenation
(2022) Araújo, Pedro Henrique Moraes de; Santana, Jordana Kaline da Silva; Sassi, Roberto; Costa, Dayane Cristina da; Antoniosi Filho, Nelson Roberto; Cordeiro, Angela Maria Tribuzy de Magalhães; Gondim, Amanda Duarte; Santos, Nataly Albuquerque dos
In line with global demand for greenhouse gas reduction, the aviation industry has invested in biofuels development. A source feedstock that deserves special mention for this process is microalgae, because of its cultivation of renewable biomass with high yields, low cost, and high CO2 sequestering potential. This research aimed the study of microalgae culture with hard potential for biofuel production and its obtaining through catalytic deoxygenation to renewable source hydrocarbons in C12–C18 range. Thus, the oils of the Scenedesmus acuminatus and Cosmarium sp. species were cultivated and identified. Scenedesmus acuminatus oil is the majority composition of palmitic acid (C16:0) and has a higher production and yield than Cosmarium sp. oil. Scenedesmus acuminatus oil was then submitted to catalytic deoxygenation by the semi-batch reaction using the 5% Pd/C catalyst. The obtained results showed a selectivity of 82.9% and n-alkane yielding of 36.6%, placing the specie as potential biojet fuel precursor.
Synergistic effect of growth conditions and organic carbon sources for improving biomass production and biodiesel quality by the microalga Choricystis minor var. minor
(2021) Oliveira, Carlos Yure Barbosa de; D'Alessandro, Emmanuel Bezerra; Antoniosi Filho, Nelson Roberto; Lopes, Rafael Garcia; Derner, Roberto Bianchini
In the search for microalgae species with potential for biodiesel production, Choricystis minor var. minor has been seen as a promising source of biomass due to its high lipid content and the satisfactory characteristics of its fatty acid methyl esters (FAMEs). For this reason, the objective of this study was to investigate the synergistic effect of growth conditions and organic carbon sources on cultivation of this microalga. To do so, experimental cultivations were conducted in photoautotrophic, heterotrophic and mixotrophic metabolisms using glucose, fructose, glycerol or sucrose – in growth conditions that use organic carbon. Thus, growth parameters of the cultures were evaluated and at the end of the cultivations, FAMEs yield and profile were determined by gas chromatography, the efficiency of carbon conversion into biomass was evaluated and a microbial analysis was conducted. Regarding growth conditions, the findings have confirmed that, regardless of the organic carbon source used, the heterotrophic and mixotrophic metabolisms can present advantages over the photoautotrophic one. In addition, biomass production was higher with the use of glucose than with other organic carbon sources, regardless of growth condition (heterotrophic or mixotrophic). Moreover, cultivations with the addition of CO2 have converted carbon into biomass less efficiently. On the other hand, photoautotrophic cultures presented the lowest bacterial load. In comparison to photoautotrophic and mixotrophic, heterotrophic cultures have led to lower FAMEs content and higher yields of unsaturated fatty acids. The most satisfactory FAMEs profile for biodiesel production was obtained with mixotrophic growth using fructose.