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Parniakov O.,CNRS Integrated Transformations of Renewable Matter | Parniakov O.,Ukrainian Academy of Sciences | Barba F.J.,University of Valencia | Grimi N.,CNRS Integrated Transformations of Renewable Matter | And 5 more authors.
Algal Research | Year: 2015

The study was aimed at investigation of the potential of pulsed electric field (PEF) pre-treatment as a preliminary step of pH-assisted aqueous extraction of algae components from microalgae Nannochloropsis suspensions. The PEF and sonication (S) were compared as pretreatment methods. They were applied at normal (pH. =. 8.5) and basic (pH. =. 11) conditions, and supplementary basic extraction (at pH. =. 11) was done. The extracts were analyzed for content of pigments, proteins, carbohydrates, total phenolic compounds and antioxidant capacity. The colloidal stability of PEF- and S-pretreated suspensions was also evaluated. The data evidence that PEF technique allows selective extraction of a portion of pure proteins that are different from proteins extracted from S-pretreated suspensions. The discovered effects have shown the advantages of PEF-pretreatment at normal conditions (pH. =. 8.5) and supplementary extraction at basic conditions (pH. =. 11) for selective extraction of different intracellular components. © 2015 Elsevier B.V. Source


Caporgno M.P.,Rovira i Virgili University | Olkiewicz M.,Rovira i Virgili University | Fortuny A.,Polytechnic University of Catalonia | Stuber F.,Rovira i Virgili University | And 6 more authors.
Fuel Processing Technology | Year: 2016

The lipid extraction using hexane and methanol:hexane increased the biodegradability of Nannochloropsis oculata by 36% and 24% respectively. Moreover, hexane increased the methane production from raw microalgae, from 253 ± 11 to 313 ± 9 mLCH4/gVS. Methanol:hexane did not affect the methane production, which yielded 254 ± 10 mLCH4/gVS, mainly due to the significant changes in the biomass composition. On the other hand, the lipid extraction failed to increase the biodegradability of Chlorella vulgaris, which resulted around 44% for raw and lipid-extracted microalgae. The methane productions were 219 ± 6, 202 ± 1 and 200 ± 4 mLCH4/gVS from raw and pre-treated microalgae using hexane and methanol:hexane respectively. Regarding the lipid extraction yields, using methanol:hexane the yields were 4.7 and 3.7 times higher for N. oculata and C. vulgaris than using hexane. The biodiesel yields were also higher using methanol:hexane, 2.4 and 1.9 times than using hexane. However, the biodiesel composition was unaffected by the solvent. The substrate to inoculum ratio influenced raw N. oculata digestion. At 1:1 VSSubstrate:VSInoculum, the methane production throughout the first days decreased but not the ultimate methane production. C. vulgaris digestion was unaffected, probably due to the biomass characteristics. Finally, the co-digestion of microalgae and sewage sludge showed no synergy, nor inhibition. © 2015 Elsevier B.V. All rights reserved. Source


Mokhtari B.,University of Laghouat | Ameur A.,University of Laghouat | Mokrani L.,University of Laghouat | Azoui B.,University of Batna | Benkhoris M.F.,37 Bd Of Luniversite
Journal of Electrical Engineering | Year: 2012

The direct torque control (DTC) of an induction motor (IM) has been the subject of several studies and developments since the eighties. Efforts have been made continuously to improve the performance of this control technique to make it more efficient and robust for industrial applications that have also experienced a remarkable development. It cites, among these applications, the tracking system, which was the subject of much research. This study provides experimental validation of the algorithms developed in this topic, and help for implementation of a simple DTC, to apply it to the tracking system, proposed by the authors. The interest of this study is that it is based on the choice of switching tables (ST) and therefore on algorithms and not on the hardware part, which is expensive. The tests were carried out under the same conditions with the same equipment of the testbed, to get a good comparative study. Three variants were tested: simple ST, table of sectors shifted by 30° and a table with 12 sectors. The results show an improvement, but a dilemma between the torque ripple and those of the stator flux. Source


Caporgno M.P.,Rovira i Virgili University | Olkiewicz M.,Rovira i Virgili University | Pruvost J.,University of Nantes | Lepine O.,37 Bd Of Luniversite | And 3 more authors.
Bioresource Technology | Year: 2016

The aim of this work was to study the effect of the solvent N-methylmorpholine-N-oxide (NMMO) to pre-treat Nannochloropsis oculata before the anaerobic digestion process. The results indicated that the pre-treatment affects the characteristics of the cell wall, which consequently becomes more susceptible to the microorganisms attack during anaerobic digestion. The methane production was increased by 43% after the pre-treatment, from 238±6mLCH4/gVS until 339±4mLCH4/gVS. On the contrary, the methane production from Chlorella vulgaris decreased after the pre-treatment from 251±4mLCH4/gVS to 231±3mLCH4/gVS. The failure on the pre-treatment was attributed to the particular characteristics of the substrate in consequence of a previous drying step. © 2015 Elsevier Ltd. Source


Caporgno M.P.,Rovira i Virgili University | Pruvost J.,University of Nantes | Legrand J.,University of Nantes | Lepine O.,37 Bd Of Luniversite | And 2 more authors.
Bioresource Technology | Year: 2016

Although the hydrothermal liquefaction is considered a promising technology for converting microalgae into liquid biofuels, there are still some disadvantages. This paper demonstrated that the bio-oil yield can be significantly improved by adding alcohols as co-solvents and carrying out the conversion at mild conditions (<250 °C), but at the expense of a reduced bio-oil quality. By adding ethanol, the bio-oil yields obtained (up to ∼60%) were comparable to the yield obtained at severe operating conditions using only water as solvent (54 ± 2% on average), but the quality of the bio-oil was lower. However, the main advantages of the process here described lie in the utilisation of wet microalgae (∼75% moisture) and alcohol concentrations which avoid both drying the microalgae and decreasing the amount of microalgae loaded in the reactor. © 2016 Elsevier Ltd. Source

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