Date of Award

Fall 2017

Document Type


Degree Name

Doctor of Philosophy (PhD)


Civil & Environmental Engineering

Committee Director

Sandeep Kumar

Committee Member

Ben Stuart

Committee Member

Gary Schafran

Committee Member

James W. Lee


In recent years, the demand for renewable energy, mainly biomass has increased. The U.S. Energy Information Administration reported that more than 13.3% of the total energy production in the first seven months of 2017 was produced from a biomass source. Among all biomass resources, microalgae has brought a lot of attention due to their numerous advantages such as higher growth rate and productivity compared with the conventional energy crops, higher energy conversion efficiency by photosynthesis, and less water requirement than terrestrial crops. However, its development is far behind industrial production. Several research efforts across the globe have been concerned with addressing the technical barriers in the commercialization of algae-based sustainable biorefineries. Nutrients cost and management have been highlighted as one of the most significant challenges in algae cultivation and downstream processing. Therefore, any technology advancement that can reduce the energy input to the process, any nutrients recycling that result in reduction of nutrients input or/and production of value-added bioproducts, will enhance the commercialization potential. This study has developed multiple viable pathways to effectively contribute to the algal based industries.

Chapter 1, includes an overall introduction through these approaches.

In Chapter 2, kinetics of peptides and arginine production from Scenedesmus sp. microalgae through flash hydrolysis (FH) were studied.

In chapter 3, the FH process on the Nannochloropsis gaditana as a high-ash marine algae was studied with focus on the biofuels intermediate (BI) characterization and the application of the hydrolysate as a nutrient source for algal cultivation.

In chapter 4, two pathways were developed to recover nutrients in the microalgae hydrolysate in the form of value-added bioproducts such as hydroxyapatite and dittmerite.

In chapter 5, the effect of reaction time on the phosphate removal from the algae hydrolysate and the chemistry of precipitates minerals were investigated.

In chapter 6, the effect of flash hydrolysis process on the lipid extractability of three algal species were investigated. In addition, biocrude yields and composition from hydrothermal liquefaction of raw and biofuels intermediates of Chlorella vulgaris were compared.

In chapter 7, several future works and research pathways were recommended by the author of this dissertation.