Hydrodynamic Optimization of the AirAccordion Photobioreactor for Microalgae Production

Persistent Link:
http://hdl.handle.net/10150/613515
Title:
Hydrodynamic Optimization of the AirAccordion Photobioreactor for Microalgae Production
Author:
He, Shiwei
Issue Date:
2016
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Algae are a prolific source of biochemicals with economic importance, including nutraceuticals, biofuels, animal feed, etc. The general aim of this study was to establish how the hydrodynamic conditions generated within specific types or designs of photobioreactors determine their respective algae growth. The specific objectives of this study were: (1) To determine and compare key hydrodynamic parameters in the Air Accordion photobioreactor and the conventional bubble column, including Residence Time, Vessel Dispersion Number, Bodenstein Number, Mixing Time and oxygen liquid mass transfer coefficient (kla); and, (2) To test how differences in the hydrodynamic conditions would result in significant difference in growths of the green alga Scenedesmus obliquuus between the photobioreactors. The results of the study showed that: (1) The Residence Time of 566 s for the Air Accordion significantly exceeded by 28% that of 444 s for the bubble column, signifying greater liquid mixing in the Air Accordion; (2) The Vessel Dispersion Number for the Air Accordion of 0.168 significantly exceeded that for the bubble column of 0.166, indicating greater degree of mixing in the Air Accordion than in the bubble column; (3) The Mixing Time in both the Air Accordion and the bubble column declined as the air flow rate increased, indicating that the tracer ions in both photobioreactors mixed more quickly. For each of the flow rates tested, however, the mixing time for the bubble column significantly exceeded that for the Air Accordion, indicating that liquid mixing in the Air Accordion occured significantly quicker than in the bubble column. At 1.0 LPM, the bubble column's Mixing Time of 10 s exceeded by 25% that of the Air Accordion of 8 s; (4) The oxygen liquid mass transfer coefficients in both photobioreactors increased as the air flow rate increased, indicating that the transfer of oxygen from the air bubbles into the liquid within the photobioreactors gained efficiency. For each of the air flow rates tested, however, the oxygen liquid mass transfer coefficient for the Air Accordion significantly exceeded that for the bubble column, indicating a significantly more efficient oxygenation of the liquid in the Air Accordion occurring than in the bubble column. At 1.0 LPM, the Air Accordion's oxygen liquid mass transfer coefficient of 0.00138 s⁻¹ exceeded by 48% that of the bubble column of 0.000931 s⁻¹; and (5) The growth of Scenedesmus obliquus in the Air Accordion significantly exceeded that in the bubble column for both 0.1 LPM and 1.0 LPM. The final algae density of 0.25 g DW/L in the Air Accordion significantly exceeded by 31% that of 0.18 g DW/L in the bubble column at 0.1 LPM. Similarly, the final algae density of 0.37 g DW/L in the Air Accordion significantly exceeded by 19% that of 0.31 g DW/L in the bubble column at 1.0 LPM. Thus, the growth of Scenedesmus obliquus in the Air Accordion photobioreactor -- with significanlty more favorable hydrodynamic characteristics in terms of Residence Time, Vessel Dispersion Number, Mixing Time and oxygen liquid mass transfer coefficient -- significantly exceeded algae growth in the bubble column of the same volume and under the same environmetal conditons.
Type:
text; Electronic Thesis
Keywords:
hydrodynamic conditions; photobioreactor; scenedesmus obliquus; Agricultural & Biosystems Engineering; algae
Degree Name:
M.S.
Degree Level:
masters
Degree Program:
Graduate College; Agricultural & Biosystems Engineering
Degree Grantor:
University of Arizona
Advisor:
Cuello, Joel

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleHydrodynamic Optimization of the AirAccordion Photobioreactor for Microalgae Productionen_US
dc.creatorHe, Shiweien
dc.contributor.authorHe, Shiweien
dc.date.issued2016-
dc.publisherThe University of Arizona.en
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en
dc.description.abstractAlgae are a prolific source of biochemicals with economic importance, including nutraceuticals, biofuels, animal feed, etc. The general aim of this study was to establish how the hydrodynamic conditions generated within specific types or designs of photobioreactors determine their respective algae growth. The specific objectives of this study were: (1) To determine and compare key hydrodynamic parameters in the Air Accordion photobioreactor and the conventional bubble column, including Residence Time, Vessel Dispersion Number, Bodenstein Number, Mixing Time and oxygen liquid mass transfer coefficient (kla); and, (2) To test how differences in the hydrodynamic conditions would result in significant difference in growths of the green alga Scenedesmus obliquuus between the photobioreactors. The results of the study showed that: (1) The Residence Time of 566 s for the Air Accordion significantly exceeded by 28% that of 444 s for the bubble column, signifying greater liquid mixing in the Air Accordion; (2) The Vessel Dispersion Number for the Air Accordion of 0.168 significantly exceeded that for the bubble column of 0.166, indicating greater degree of mixing in the Air Accordion than in the bubble column; (3) The Mixing Time in both the Air Accordion and the bubble column declined as the air flow rate increased, indicating that the tracer ions in both photobioreactors mixed more quickly. For each of the flow rates tested, however, the mixing time for the bubble column significantly exceeded that for the Air Accordion, indicating that liquid mixing in the Air Accordion occured significantly quicker than in the bubble column. At 1.0 LPM, the bubble column's Mixing Time of 10 s exceeded by 25% that of the Air Accordion of 8 s; (4) The oxygen liquid mass transfer coefficients in both photobioreactors increased as the air flow rate increased, indicating that the transfer of oxygen from the air bubbles into the liquid within the photobioreactors gained efficiency. For each of the air flow rates tested, however, the oxygen liquid mass transfer coefficient for the Air Accordion significantly exceeded that for the bubble column, indicating a significantly more efficient oxygenation of the liquid in the Air Accordion occurring than in the bubble column. At 1.0 LPM, the Air Accordion's oxygen liquid mass transfer coefficient of 0.00138 s⁻¹ exceeded by 48% that of the bubble column of 0.000931 s⁻¹; and (5) The growth of Scenedesmus obliquus in the Air Accordion significantly exceeded that in the bubble column for both 0.1 LPM and 1.0 LPM. The final algae density of 0.25 g DW/L in the Air Accordion significantly exceeded by 31% that of 0.18 g DW/L in the bubble column at 0.1 LPM. Similarly, the final algae density of 0.37 g DW/L in the Air Accordion significantly exceeded by 19% that of 0.31 g DW/L in the bubble column at 1.0 LPM. Thus, the growth of Scenedesmus obliquus in the Air Accordion photobioreactor -- with significanlty more favorable hydrodynamic characteristics in terms of Residence Time, Vessel Dispersion Number, Mixing Time and oxygen liquid mass transfer coefficient -- significantly exceeded algae growth in the bubble column of the same volume and under the same environmetal conditons.en
dc.typetexten
dc.typeElectronic Thesisen
dc.subjecthydrodynamic conditionsen
dc.subjectphotobioreactoren
dc.subjectscenedesmus obliquusen
dc.subjectAgricultural & Biosystems Engineeringen
dc.subjectalgaeen
thesis.degree.nameM.S.en
thesis.degree.levelmastersen
thesis.degree.disciplineGraduate Collegeen
thesis.degree.disciplineAgricultural & Biosystems Engineeringen
thesis.degree.grantorUniversity of Arizonaen
dc.contributor.advisorCuello, Joelen
dc.contributor.committeememberSlack, Donalden
dc.contributor.committeememberFitzsimmons, Kevinen
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