Date of Award

2010

Degree Type

Thesis

Degree Name

Master of Engineering Science

Program

Chemical and Biochemical Engineering

Supervisor

Dr. Amarjeet S. Bassi

Abstract

The use of microalgae as feed stock for biodiesel production has been under consideration for a number of years. However the process design always had limitations which were associated with the extraction and the harvesting processes. Biodiesel production from microalgae is an important process component in the microalgal biofuel area. In this project, a method for the cultivation of Chlorella vulgaris (UTEX 2714) on anaerobically digested dairy farm effluent is proposed. The first part of the work provides a study on the feasibility of microalgae cultivation on pre-treated dairy farm effluent. The microalgae were cultivated using 2% (v/v) and 4% (v/v) CO2 and two different pre-treatment techniques were employed i.e. using aluminum sulphate and the other using ferric sulphate. The pre treatment method employing doses of aluminum sulphate and ferric sulphate which provided the best results were 11 g/L and 7 g/L respectively. Triglyceride extractions were carried out using a modified Bligh and Dyer method which yielded triglyceride content to be in the range 17.65 - 22.85 % by weight. The microalgae were capable of removing 80.3 - 83.2 % of the initial NO3', 100 % of the initial NH/, 39.8 - 45.1 % of the initial phosphate and 52.8 - 65.4 % of the initial COD concentrations. The maximum dry weight recorded in these experiments was 2.05 g/L. The post harvesting and concentration resulted in a microalgal slurry with a final dry weight concentration of 15 g/L was obtained. The harvested microalgae cells were then freeze dried for solvent extraction and Insitu biodiesel production. In the second part of the project, the focus was drawn to performing triglyceride extractions and biodiesel production from microalgae using an acid catalyst. For the various microalgae samples iii cultivated in the tubular photo bioreactor setup, yield calculations and FAME profiles were developed. A biodiesel yield maximum of 26.67 % by wt. was determined for the microalgae cultivated on dairy farm effluent using a 7 g/L ferric sulphate salt solution as the pre-treatment method. The FAME profile obtained in majority of the microalgae cultivated was mainly composed of C16, C18:0, Cl8:1, C18:2 fatty acids. This composition obtained for the microalgae very closely resembled the triglyceride composition obtained for canola oil derived biodiesel.

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