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Author
Title Optimization of vertical photobioreactors
URL
Publication Date
Degree MS(M.S.)
Discipline/Department Chemical Engineering
Degree Level masters
University/Publisher University of Dayton
Abstract This study focuses on optimizing the design of a photobioreactor to increase carbon dioxide sequestration by phototrophic microalgae. It is known that a significant amount of carbon dioxide emissions can be attributed to energy production processes and is expected to increase as global energy needs increase. The carbon dioxide emissions can be reduced by feeding carbon dioxide in the flue gas from power generation to an algal cultivation system. To increase carbon dioxide sequestration, it is imperative that an economical and robust photobioreactor that is capable of operating in any weather condition and location be designed. The focus of this study was to optimize vertical photobioreactors that are known to have a higher aerial productivity (higher biomass per unit area) and hence more efficient in sequestering carbon dioxide than the horizontal reactors. Horizontal tubular photobioreactor and vertical bubble column type units differ substantially in many ways; particularly with respect to the surface-to-volume ratio, the amount of gas in dispersion, the gas-liquid mass transfer characteristics, hydrodynamics, and internal irradiance levels. The effect of superficial velocity, temperature, carbon dioxide concentration, light irradiance, illuminated surface-to-volume ratio, pH, and gas holdup, and reactor geometry (diameter and height) were investigated with the algal specie Chlorella vulgaris in vertical bubble column reactors. Experiments were conducted on vertical photobioreactors of 2, 3, 4, 5, 6, 12, and 18 inch diameters of various heights (5, 8, and 10 feet) by changing the parameters that affect the algal density. In addition to the vertical bubble column configuration, algal densities in split and co-annular reactor designs were also investigated and found to be 1.334 and 1.842 g/L respectively.At the conditions studied, the 3 inch diameter vertical bubble column reactor produced the highest algal density (5.21 g/L) and the other reactors with 2, 4, 5, 6, 12 and 18 inch diameters reached densities of 0.938, 3.611, 3.296, 2.417, 1.665, 0.919 g/L respectively. The results show, that an increase in the ratio of the illuminated surface area to liquid volume in the reactor proportionately increases the biomass yields in vertical bubble column reactors and has the most effect on the final biomass yield in a vertical bubble column reactor. It was observed that increasing the reactor height from 5 feet to 10 feet had no effect on the biomass yields. Increasing the growth temperature from 20 to 35°C increased the biomass yields (20-27%) of Chlorella vulgaris. Increasing the CO2 concentration up to 9% in the air / CO2 flow increased the biomass yields and provided asufficient level of pCO2 while maintaining the pH level required for algal growth in the reactor geometries tested. This thesis stands out from others in presenting the data for larger operating volumes and geometries of vertical reactors (bubble column, split and co-annular). The growth data from a reactor with an 18 inch diameter and a…
Subjects/Keywords Alternative Energy; Optimization of vertical photobioreactor; Bubble column; Split column; Draft column reactors; vertical photobioreactor geometries; increase of height of vertical photobioreator; Effect Temperature Chlorella Vulgaris on photobioreactors; Coannular reactor
Contributors S. Sidhu, Sukh (Committee Chair)
Language en
Rights unrestricted ; This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
Country of Publication us
Format application/pdf
Record ID oai:etd.ohiolink.edu:dayton1355193893
Repository ohiolink
Date Retrieved
Date Indexed 2016-12-22
Grantor University of Dayton

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…22 4.2.2 Vertical photobioreactor – bubble column reactor ..................................... 23 4.2.3 Split column reactors .................................................................................. 26 4.2.4 Co-annular reactors…

…of vertical reactors were discussed by Fernandez [4]. Figure 4 shows the three vertical photobioreactors - (a) bubble, (b) draft and (c) split column. Each reactor has its own mixing pattern and is designed in…

…such a way to move the algae cell more into the light zone. The bubble column is aerated using air and CO2 at the bottom of the reactor. 10 (a) (b) (c) Figure 4 Configuration of three vertical photobioreactors [4…

…mixing pattern), superficial velocity, gas holdup, and light availability. Light availability in the reactor plays an important role in increasing the algal density. Light availability in bubble column is influenced by aeration rates, gas holdup, and…

…required for a bubble a column reactor, and significantly less than the 2000–3000 W/m3 required for a horizontal tubular photobioreactor [22]. The higher volumetric power requirement is to be expected for a horizontal reactor due to its design…

…medium should be maintained in the range that sustains the growth of the particular algal specie. The CO2 concentration has a direct impact on the pH of the reactor. Hulatt et al. studied the bubble column reactors with CO2 concentrations of 0.04, 4, 12…

…Dunaliella tertiolecta in a 1.4 L vertical bubble column reactor with the nutrient composition listed in BBM (Basel’s bold medium) (see appendix section A.1 for composition) [18]. The yields (gram per liter) were…

…34 5.2.1 Horizontal photobioreactors ....................................................................... 34 5.2.2 Vertical reactors - Bubble Column ............................................................. 40 5.3 REACTORS CONFIGURED FOR…

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