Μελέτη της διεργασίας παραγωγής βιοαιθανόλης από διατροφικά απορρίμματα

107 σ.Η παραγωγή βιοκαυσίμων, και συγκεκριμένα βιοαιθανόλης, από βιομάζα αποτελεί το κέντρο επιστημονικού και βιομηχανικού ενδιαφέροντος τα τελευταία χρόνια. Συγκεκριμένα για να αποκτήσει βιώσιμο χαρακτήρα η παραγωγή 2ης γενιάς βιοαιθανόλης, η προσπάθεια έχει επικεντρωθεί στην μείωση του κόστους των πρώτων υλών. Η διαχείριση των διατροφικών απορριμμάτων είναι ένα σημαντικό ζήτημα τόσο για την προστασία του περιβάλλοντος, όσο και για τη διατήρηση των πόρων. Η μετατροπή των υπολειμμάτων των τροφών σε αιθανόλη θα μπορούσε να προσφέρει περαιτέρω οικονομικά πλεονεκτήματα, λόγω της αύξησης του κόστους διάθεσης των απορριμμάτων. Το γεγονός ότι τα διατροφικά απορρίμματα είναι πλούσια σε ζυμώσιμα σάκχαρα, τα καθιστά κατάλληλη πρώτη ύλη για παραγωγή βιοαιθανόλης, ενός εναλλακτικού και ανανεώσιμου καυσίμου κίνησης. Σκοπός της παρούσας διπλωματικής εργασίας είναι η μελέτη της διεργασίας παραγωγής βιοαιθανόλης από διατροφικά απορρίμματα και η βελτιστοποίηση των συνθηκών παραγωγής της. Αρχικά, η πρώτη ύλη προκατεργάζεται υδροθερμικά σε θερμοκρασία 100ο C για 1 hour παρουσία και μη H2SO4 σε περιεκτικότητα 1g/100g στερεού, με συγκέντρωση στερεού 30 % β/ο . Το ποσοστό του αμύλου που αποικοδομείται είναι 47,13% μετά από υδροθερμική προκατεργασία παρουσία H2SO4, 1g/100g ξ.σ. και 45,72% μετά από υδροθερμική προκατεργασία απουσία οξέος. Ακολουθεί ενζυμική υδρόλυση του προκατεργασμένου υλικού με χρήση αμυλολυτικών (Liquozyme SC DS και Spirizyme Fuel ) με ενεργότητες 0,053U/g αμύλου για την α-αμυλάση και 5.06, 10.2, 20.24 U/g αμύλου για την γλυκοαμυλάση και κυτταρινολυτικών (Celluclast 1,5L/Novozyme 188 (5:1) και Cellic® CTec2) εμπορικά διαθέσιμων ενζυμικών σκευασμάτων με ενεργότητες 1,3,5,7,9 FPU/g υλικού. Η υδρόλυση του αμύλου κυμαίνεται μεταξύ 72,30 και 86,32%. Το θεωρητικό ποσοστό υδρόλυσης της κυτταρίνης με βάση την παραχθείσα γλυκόζη κατά την υδρόλυση με μίγμα Celluclast 1,5L/Novozyme 188 (5:1) κυμαίνεται μεταξύ 75,28% και 97,63%, ενώ όσον αφορά στην υδρόλυση με χρήση του σκευάσματος Cellic® CTec2 το αντίστοιχο ποσοστό είναι 25,70% έως 64,22%. Τέλος, πραγματοποιείται μελέτη της συμπεριφοράς των αμυλολυτικών και κυτταρινολυτικών ενζυμικών σκευασμάτων καθώς και της συνεργιστικής τους δράσης κατά την παραγωγή αιθανόλης με εφαρμογή της τεχνολογίας ταυτόχρονης σακχαροποίησης και ζύμωσης (SSF). Οι ενζυμικές ενεργότητες που εφαρμόζονται στο στάδιο των ζυμώσεων είναι αυτές που παρουσιάζουν τα βέλτιστα αποτελέσματα κατά την υδρόλυση του υλικού. Η παραγωγικότητα της διεργασίας κυμάνθηκε από 0,08-0,26 g/L*h. Το εύρος τιμών παραγωγής αιθανόλης κατά την ζύμωση είναι 7,22±0,84 – 18,70±0,13g/L, ενώ τα ποσοστά % των μέγιστων θεωρητικών αποδόσεων είναι 68,87±1,09 και 288,30±4,43 βάσει της μέγιστης παραγόμενης αιθανόλης των μη δομικών σακχάρων, της κυτταρίνης και του αμύλου και βάσει της μέγιστης παραγόμενης αιθανόλης από τα μη δομικά σάκχαρα.The production of biofuels, particularly bioethanol, by biomass has been the center of scientific and industrial interest in the recent years. Specifically, in order for the production of second generation bioethanol to become sustainable, a considerable effort is placed into reducing the cost of raw materials. The management of food waste is a major concern in terms of protecting the environment and conserving the resources. The conversion of waste food into ethanol could potentially offer further cost advantages, due to the rising cost of waste disposal. The fact that food waste is rich in fermentable sugars, makes it suitable feedstock for bioethanol, an alternative and renewable transport fuel. The purpose of this thesis is to study the process of bioethanol production from food waste and optimize the respective production conditions. Initially, the raw material is pretreated hydrothermally at 100°C temperature for 1 hour with and without the presence of H2SO4 in solid content 1g/100g, with a concentration of solid of 30% w/v. The percentage of starch is degraded 47.13% after hydrothermal pretreatment with H2SO4, 1g/100g of substrate and 45.72% after hydrothermal pretreatment without acid. Enzymatic hydrolysis of the pretreated material is carried out using amylolytic (Liquozyme SC DS and Spirizyme Fuel) with activities 0,053 U / g of starch to alpha-amylase and 5.06, 10.2, 20.24 U / g starch to glucoamylase and cellulolytic (Celluclast 1,5 L / Novozyme 188 (5:1) and Cellic ® CTec2) commercially available enzymes with activities 1,3,5,7,9 FPU / g material. Starch hydrolysis is between 72.30% and 86.32%. The theoretical rate of hydrolysis of the cellulose, based in the produced glucose during the hydrolysis with mixture of Celluclast 1,5 L / Novozyme 188 (5:1) is between 75.28% and 97.63%, while regarding the hydrolysis by using the formula Cellic ® CTec2 the figure is 25.70% to 64.22%. Finally, it is studied the behavior of amylolytic and cellulolytic enzyme formulas and their synergistic effect against the production of ethanol by application of the technology of simultaneous saccharification and fermentation (SSF). The enzyme activities applied at the stage of fermentation are those that show the best results in the hydrolysis of the material. The process productivity ranged from 0,08-0,26 g / L * h. The range of ethanol production during fermentation is 7,22 ± 0,84 - 18,70 ± 0,13 g / L, while the percentage of the maximum theoretical yield is 68,87 ± 1,09 and 288,30 ± 4, 43 based on the maximum of the produced ethanol from nonstructural sugars, cellulose and starch and the maximum ethanol produced from the non-structural sugars.Γεωργία Ν. Παπαδοπούλο

Geotechnical foundation conditions of Mesologion swimming pool center

Η επιλογή του καταλληλότερου τύπου θεμελίωσης εμπεριέχει την εξέταση ποικίλλων παραμέτρων. Στην περίπτωση του Κολυμβητηρίου Μεσολογγίου, έγινε μια προσπάθεια πρότασης ενός τύπου θεμελίωσης, κατάλληλου από γεωτεχνικής πλευράς, για ιζήματα που βρίσκονται πολύ κοντά στη θάλασσα. Το υπέδαφος εκεί, αποτελείται από μαλακά, λεπτόκοκκα, χαμηλής πλαστικότητας υλικά, CL μέχρι SL, με εναλλαγές υψηλής πλαστικότητας αργιλικών στρωμάτων CH. Επιπρόσθετα η στάθμη του υπόγειου υδροφόρου εντοπίζεται στα 0,8 μέτρα κάτω από την επιφάνεια του εδάφους. Ή δυσκολία εξασφάλισης αδιατάραχτων δειγμάτων λόγω κατάστασης υλικού, μας ανάγκασε να στηριχτούμε για τους υπολογισμούς των παραμέτρων στα αποτελέσματα των επί τόπου δοκιμών. Σκοπός της εργασίας αυτής είναι να παρουσιάσει τα υλικά των ιζημάτων, τις εδαφοτεχνικές τους παραμέτρους, τη μεθοδολογία, τους υπολογισμούς και την πρόταση θεμελίωσης για κολυμβητήριο Μεσολογγίου.Although geotechnical tests are standard and commonly used in determining the foundation type to be applied, in some cases the use ofin-situ tests are essential in order to obtain the correct values needed in the geotechnical calculations. In the case of the foundation of Mesologi Swimming-pool Center, an attempt was made to propose a foundation type, suitable from geotechnical point of view, for sediments that lie very close to the sea! The selection of the most suitable foundation type encloses the examination of several parameters. The subsoil there, consists of soft, fine grained, low plasticity materials, CL to SL with alternations of high plasticity clay layers CH. Additionally, the groundwater level is 0,8 meters under the soil surface, demonstrating constant saturation conditions. The combination of soft subsoil layers quality and the high level of groundwater leads to difficult foundation conditions in relation to immediate and secondary consolidation settlement. Geotechnical calculations and calculations of settlement were performed and the most suitable foundation type was semi-compensated mat foundation

Indicators for the Sea-floor Integrity of the Hellenic Seas under the European Marine Strategy Framework Directive: establishing the thresholds and standards for Good Environmental Status

A data set of 625 samples of benthic macroinvertebrates collected from the Hellenic Seas (Ionian and Aegean) was used to establish thresholds and reference standards for two of the indicators addressing the descriptors of Sea-floor Integrity under the Marine Strategy Framework Directive (MSFD): species diversity and richness and the ratio of sensitive species to tolerant species. The dataset was categorised according to the baseline ecological status assessment of the respective water bodies under the Water Framework Directive (WFD). Species diversity and richness were characterised using the Shannon diversity and species richness indices, respectively, and were analysed for three pre-defined substrate types, three depth zones and three sample-size categories, and the significant categories were statistically validated. Good Environmental Status (GEnS) threshold and reference values were established for the valid combinations of categories denoted as ‘ecotypes’ through the use of a boxplot and an analysis of variance. The limitations and specifications for an overall GEnS assessment using the above indices are highlighted based on the WFD experience. For the ratio of sensitive species to tolerant species, the BENTIX index classification scale is proposed for GEnS assessment, and an integrated approach to the assessment of diversity and species richness is suggested. Finally, the regionality of the tested indices in relation to the two Mediterranean sub-regions, including the Hellenic area, was tested

Reliability and psychometric properties of the Greek translation of the State-Trait Anxiety Inventory form Y: Preliminary data

BACKGROUND: The State-Trait Anxiety Inventory form Y is a brief self-rating scale for the assessment of state and trait anxiety. The aim of the current preliminary study was to assess the psychometric properties of its Greek translation. MATERIALS AND METHODS: 121 healthy volunteers 27.22 ± 10.61 years old, and 22 depressed patients 29.48 ± 9.28 years old entered the study. In 20 of them the instrument was re-applied 1–2 days later. Translation and Back Translation was made. The clinical diagnosis was reached with the SCAN v.2.0 and the IPDE. The Symptoms Rating Scale for Depression and Anxiety (SRSDA) and the EPQ were applied for cross-validation purposes. The Statistical Analysis included the Pearson Correlation Coefficient and the calculation of Cronbach's alpha. RESULTS: The State score for healthy subjects was 34.30 ± 10.79 and the Trait score was 36.07 ± 10.47. The respected scores for the depressed patients were 56.22 ± 8.86 and 53.83 ± 10.87. Both State and Trait scores followed the normal distribution in control subjects. Cronbach's alpha was 0.93 for the State and 0.92 for the Trait subscale. The Pearson Correlation Coefficient between State and Trait subscales was 0.79. Both subscales correlated fairly with the anxiety subscale of the SRSDA. Test-retest reliability was excellent, with Pearson coefficient being between 0.75 and 0.98 for individual items and equal to 0.96 for State and 0.98 for Trait. CONCLUSION: The current study provided preliminary evidence concerning the reliability and the validity of the Greek translation of the STAI-form Y. Its properties are generally similar to those reported in the international literature, but further research is necessary

Non-Isothermal Crystallization Kinetics of PBSu/Biochar Composites Studied by Isoconversional and Model Fitting Methods

Non-isothermal crystallization of Poly(butylene succinate) (PBSu)/biochar composites was studied at various constant cooling rates using differential scanning calorimetry. The analysis of the kinetics data revealed that the overall crystallization rate and activation energy of the PBSu polymer were significantly influenced by the addition of biochar. Specifically, the PBSu/5% biochar composite with a higher filler content was more effective as a nucleation agent in the polymer matrix, as indicated by the nucleation activity (ψ) value of 0.45. The activation energy of the PBSu/5% biochar composite was found to be higher than that of the other compositions, while the nucleation activity of the PBSu/biochar composites decreased as the biochar content increased. The Avrami equation, which is commonly used to describe the kinetics of crystallization, was found to be limited in accurately predicting the non-isothermal crystallization behavior of PBSu and PBSu/biochar composites. Although the Nakamura/Hoffman–Lauritzen model performed well overall, it may not have accurately predicted the crystallization rate at the end of the process due to the possibility of secondary crystallization. Finally, the combination of the Šesták–Berggren model with the Hoffman–Lauritzen theory was found to accurately predict the crystallization behavior of the PBSu/biochar composites, indicating a complex crystallization mechanism involving both nucleation and growth. The Kg parameter of neat PBSu was found to be 0.7099 K2, while the melting temperature and glass transition temperature of neat PBSu were found to be 114.91 °C and 35 °C, respectively, very close to the measured values. The Avrami nucleation dimension n was found to 2.65 for PBSu/5% biochar composite indicating that the crystallization process is complex in the composites

Taylor-Couette instability in disk suspensions: Experimental observation and theory

Using the well-known hydrodynamic theory for dilute suspensions of spheroids, we have previously predicted the destabilization of Taylor-Couette flow due to anisotropic viscous stresses induced by suspended disk-shaped particles [Gillissen and Wilson, Phys. Rev. Fluids 3, 113903 (2018)]. Here we provide experimental evidence for the destabilization mechanism using suspensions of mica flakes. There is good qualitative agreement between the experiment and theory in the mica concentration dependence of the critical speed for instability onset and of the axial wavelength of the corresponding Taylor vortices. Quantitative differences are attributed to hydrodynamic interactions between the disks, which we account for in the theory in an ad hoc fashion using rotary diffusion