Doctoral Dissertations


Aastha Ojha


"The major hindrances to large scale cultivation of microalgae are the problems associated with the design, operation, and scale-up of airlift photobioreactors (PBRs), due to a lack of a comprehensive understanding of the gas-liquid interaction process in real microalgae cultures. Thus, the overall objective of this work is to advance the fundamental understanding of microalgae culturing via gas holdup, bubble dynamics, mass transfer, and dynamic growth investigations.

First, a four-point optical fiber probe technique was employed to study the local gas holdup, and bubble dynamics properties such as bubble passage frequency, chord length and bubble velocity distribution, and interfacial area in an air-water system in a split airlift PBR at superficial gas velocities between 0.3-2.8 cm/s. These properties were then studied in green fresh-water microalgae, Scenedesmus, grown inside the PBR, and their variation with a change in the optical density and rheology of the medium due to microalgae growth was also studied.

For mass transfer investigation, the significance and development of a new approach to calculate the liquid side and the local volumetric mass transfer coefficient was established in an air-water system. This new approach was then applied to estimate the local mass transfer coefficient in the Scenedesmus culture, as it grew in optical density.

Finally, a separate-effects experiment was developed to estimate the dynamic growth kinetics parameters of microalgae Scenedesmus, by measuring its growth rate and fluorescence in a tubular airlift PBR"--Abstract, page iv.


Al-Dahhan, Muthanna H.

Committee Member(s)

Sitton, Oliver C., 1951-
Forciniti, Daniel
Park, Joontaek
Mormile, Melanie R.


Chemical and Biochemical Engineering

Degree Name

Ph. D. in Chemical Engineering


Missouri University of Science and Technology

Publication Date

Fall 2016

Journal article titles appearing in thesis/dissertation

  • Investigation of local gas holdup and bubble dynamics using four-point optical probe technique in a split airlift bioreactor
  • A new approach for evaluating the local volumetric mass transfer coefficient in a split airlift reactor
  • Local gas holdup and bubble dynamics investigation during microalgae culturing in a split airlift photobioreactor
  • Estimating the local volumetric mass transfer coefficient for microalgae scenedesmus in a split airlift photobioreactor
  • Dynamic growth investigation of the microalgae scenedesmus for estimating the dynamic kinetic growth model parameters


xv, 219 pages

Note about bibliography

Includes bibliographic references.


© 2016 Aastha Ojha, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Subject Headings

Algae culture
Bubbles -- Dynamics -- Models
Bubbles -- Dynamics -- Computer simulation

Thesis Number

T 11045

Electronic OCLC #