Date of Graduation

5-2018

Document Type

Thesis

Degree Name

Bachelor of Science in Biological Engineering

Degree Level

Undergraduate

Department

Biological and Agricultural Engineering

Advisor

Zhang, Wen

Reader

Costello, Thomas

Second Reader

Osborn, Scott

Abstract

Biofuels produced from algae have the prospect to provide a cheap, carbon neutral alternative to fossil fuels. However, the high cost for harvesting algae limits its wide application, as the preferred algae strains for biofuel production are typically unicellular microalgae that do not settle in water very well. Recently, researchers have been focusing on developing a biological method to achieve the sedimentation of algae through flocculation. A recent study has concluded that introducing microalgae that self-flocculates increases the recovery of the desired microalgae, similar to the effect of using coagulant to flocculate the algae. This option can potentially be more eco-friendly without added cost of extra chemicals.

This project explored the effect of auto-flocculation in microalgae when wastewater is used as nutrient source. This project showed that growing the self-flocculating algae Scenedesmus dimorphus with Chlorella vulgaris did not result in an increase of recovery efficiency from the wastewater after nine hours of sedimentation. When grown together, there was a slight shift to larger particle sizes than that of C. vulgaris alone, but it did not correlate into an increase of recovery. The growth of the two species together produced a lower amount of lipids than that of C. vulgaris alone, but approximately the same amount of biomass concentration. Further study is recommended to determine if other species of self-flocculating microalgae can produce the desired flocculation effect.

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