Electronic Thesis and Dissertation Repository

Thesis Format



Master of Engineering Science


Chemical and Biochemical Engineering

Collaborative Specialization

Environment and Sustainability


Bassi, Amarjeet


The objective of this study was to investigate the properties of sustainable replacements for plastics and diesel fuel, derived from microalgae (Chlorella vulgaris) subjected to steam explosion. During the process, oven temperatures of up to 500 °C were reached, with the experiments left for different times after reaching their maximum internal temperature. Lipids were extracted from algal cultures using a modified Folch method. The waste microalgae were combined with pectin and glycerol to form biodegradable films, and their solubilities and tensile strengths were measured. The highest yield was 124 mg lipids/g microalgae from 400 °C steam explosion for 45 minutes after reaching maximum conditions. The highest tensile strength of the pectin films was 10.8 MPa, from 400 °C steam exploded microalgae. Overall, steam explosion can improve lipid accessibility and tensile properties of pectin films, and a major recommendation was to perform a life cycle analysis on the entire process to determine energy balances and its impact on the environment.

Summary for Lay Audience

The use of plastic and diesel made from crude oil has severely affected the health of people around the world, as well as the health of the water and land surrounding them. Alternatives from microalgae are promising, as they greatly reduce land use and hence reduce the burden on the environment. Examples of these products are biodiesel and bioplastics, both of which were researched in this study, and are completely biodegradable. To produce biodiesel, molecules known as lipids must be reacted with an alcohol. However, in Chlorella vulgaris, a type of microalgae, these lipids are protected by a thick cell wall which makes it difficult to extract them. Steaming the microalgae under high temperature and pressure, then quickly decreasing the pressure broke the cell walls and allowed more of the lipids to be extracted. This technique is known as steam explosion. After lipids were extracted from steam exploded microalgae, the remaining debris was then combined with glycerol and pectin to produce bioplastic films.

Creative Commons License

Creative Commons Attribution-Noncommercial 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License


Author noted enzyme that was omitted from sentence: Page 29, Section 4.1, Paragraph 1, Line 5: “by the fact that has been theorised"... should read “by the fact that lysozyme has been theorised"...