Identifying and Characterising MicroalgalStrains as Potential Sources of Biodiesel

Transcription

1 Identifying and Characterising MicroalgalStrains as Potential Sources of Biodiesel Krys Bangert Dr D.J. Gilmour -8th June

2 Mini project overview & Aims Continue the work by previous E-Futures DTC Students on: Effects of NaCl (Salt) stress Total lipid production Cell growth Study the effect of continuous culture using a lab based photobioreactor. Species of study: Tetraselmis suecica

3 Why use Algae to make fuel? Fossil oil resources becoming depleted Algal biodiesel production almost carbon neutral Can be made using existing infrastructure Synergy with other systems like anaerobic digestion Rapid growth (exponential) and high oil content, 80% compared to 5% for 1 st gen fuel crops. Small amount of land needed for growth, no fuel for food issues.

4 How to make biodiesel Trans-esterification process Triglyceride (parent oil) Methanol or Ethanol E.g. acids, alkalis or lipase enzymes Glycerol Methyl esters (biodiesel)

5 How Tetraselmis responds to Stress External Other factors salinity can out cause of External balance, salinity osmosis balanced draws Cell stress produces for more prolonged water with periods, from compatible cell cell cytoplasm. cytoplasm. solute. Osmotic such gradient as: Algal Nitrogen Salinity cell of inoculated = Cell stabilised. starvation solution into Temperature = increased is No a stressed. solution Cell division Cell division reduced as and = TAG Cell CO lipids is 2 starvation not normal built stressed, up functions for when conditions as normal. This can lead to more more useful favourable. TAG Lipid production

6 How Tetraselmis responds to Stress External Other factors salinity can out cause of External balance, salinity osmosis balanced draws Cell stress produces for more prolonged water with periods, from compatible cell cell cytoplasm. cytoplasm. solute. Osmotic such gradient as: Algal Nitrogen Salinity cell of inoculated = Cell stabilised. starvation solution into Temperature = increased is No a stressed. solution Cell division Cell division reduced as and = TAG Cell CO lipids is 2 starvation not normal built stressed, up functions for when conditions as normal. This can lead to more more useful favourable. TAG Lipid production

7 Continuous culture and mass production Open raceway ponds Simple design Low operation costs High levels of contamination Not optimised Photobioreactor High density cultures Controlled conditions Early commercialisation High operation costs Small batch sizes

8 Experiment and Method Two batches run in an airlift bioreactor Both using Dunaliella growth medium First a 0.5M and then at 1.5M NaCl concentration. Samples taken regularly for Cell counting and Lipid anaylsis. Existing cultures used for innoculation

9 Our test rig Air in Air out Medium inlet Stand Aerator Water jacket in Airlift Fermenter Water jacket out Sample outlet

10 M NaCl Lipid Results % Lipid produced 09/05/ /05/ /05/ /05/ /05/ /05/ /05/ /05/ /05/ /05/ /05/2010 Date Percentage of total Lipids Trend shows that total lipids decrease with age of culture

11 1.40E E E E E E E E M NaCl Growth Results Trend shows a typical algal growth pattern. Mean Cell number 05/05/ /05/ /05/ /05/ /05/ /05/ /05/ /05/ /05/ /05/ /05/ /05/ /05/ /05/ /05/2010 Date Tetraselmis Cell Growth Lag phase. Exponential phase. 2 3 Stationary phase. 1

12 0.5M NaCl Lipid Results data Lipid and cell count over time Highest lipid production at end of exp. phase Number of cells Percentage of lipid Lipids reduced in stationary phase Duration of study (Days) 10 0 Trend differs to predicted results Cells ml-1 Lipid/Biomass %

13 Conclusions Tetraselmis can produce large amounts of lipid Early harvesting would produce largest oil yield Higher salinity (1.5M), reduces growth rate Problems with wall growth, esp at high salinities. Aeration level and reactor fluid flow have large impact on cell count. Gravimetric Lipid method, inefficient and prone to error.

14 Future work Further study needed with increased sample rate. Other lipid count methods to be tried. Flow cytometry and fluorescence microscopy. Wall growth issues need resolving. Effects of ph, C0 2 and further salinities to be measured.

15 Any Questions? Special thanks to my supervisor, Dr D. J. Gilmour; PhD students; JasemAlmohsen, Ibrahim Alshubaith, Mohammed Al-Malkiand Abdolkader Mohmmed; And fellow DTC Students Emily Hounslow and PhilippaUttley.