Friday, February 17, 2017
Exhibit Hall (Hynes Convention Center)
Elena Koung, Texas Junior Academy of Science, Richardson, TX
Although the algal biofuel industry is growing, it is inhibited by the high cost of harvesting lipids and the energy used to harvest this energy exceeds the energy that is created. In addition, conventional methods of extracting algal lipids are extremely environmentally harmful because it uses toxic chemicals, such as chloroform and methanol, that require special disposal methods and ultimately wastes resources. This project tests the feasibility of osmotic pressure to remove lipids from algae. If osmotic pressure is induced to make Chlorella vulgaris and Chlamydomonas reinhardtii excrete lipids, then, when placed into salt water baths with concentrations of 5%, 10%, 15%, and 20%, the highest lipid yield from both species will come from the 20% concentration of salt.

Two potential algae strains, Chlorella vulgaris and Chlamydomonas reinhardtii, were cultured under the same conditions controlled with a photobioreactor that was designed by the student for inexpensive and continued use. After 2 weeks of culturing, the two species were placed into their respective baths of 5%, 10%, 15%, and 20% salt concentrations. Salt was chosen because it is reusable and cheap; it will create a hypertonic solution in which the algae will shrink and excrete lipids. FT-IR ATR spectroscopy was used to collect data on the concentration and presence of lipids in the algae. Nile red was used to depict the decrease of lipids in the algae. It was found that in the 20% bath, both species of algae experienced a statistically significant decrease in the lipid concentration after the 3rd week. Osmotic pressure is confirmed as viable in removing lipids from Chlorella vulgaris and Chlamydomonas reinhardtii. The current gold standard of lipid removal, Bligh-Dyer Method, yields only 22% total lipid concentration. Most notably, the experimental group for Chlorella vulgaris, at 20% salt concentration, had 74.5% total lipids extracted. If osmotic pressure could be effectively used to harvest a significant amount lipids from algae, then the market for biofuels could potentially increase. In this experiment, salt instead of chemicals like chloroform and methanol was used. The salt creates an inexpensive and environmentally friendly alternative to these chemicals. It is inexpensive because of its abundance and can be reused many times, therefore saving resources. This experiment provides a reproducible cleaner and cheaper method for lipid extraction in Chlorella vulgaris and Chlamydomonas reinhardtii.