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Batch and Fed Batch Cultivation and Harvesting of Nannochloropsis Gaditana for Environmental Applications

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Batch and Fed Batch Cultivation and Harvesting of Nannochloropsis Gaditana for Environmental Applications Western University Scholarship@Western Electronic Thesis and Dissertation Repository 7-11-2017 12:00 AM Batch and Fed Batch Cultivation and Harvesting of Nannochloropsis Gaditana for Environmental Applications Roopa P. Devasya The University of Western Ontario Supervisor Dr Amarjeet Bassi The University of Western Ontario Graduate Program in Chemical and Biochemical Engineering A thesis submitted in partial fulfillment of the equirr ements for the degree in Doctor of Philosophy © Roopa P. Devasya 2017 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Chemical Engineering Commons Recommended Citation Devasya, Roopa P., "Batch and Fed Batch Cultivation and Harvesting of Nannochloropsis Gaditana for Environmental Applications" (2017). Electronic Thesis and Dissertation Repository. 4670. https://ir.lib.uwo.ca/etd/4670 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. Abstract The exhaustion of fossil fuels and climate change are two significant issues of our times. Microalgae are eukaryotic phototrophs or prokaryotic cyanobacteria (blue green algae), which are able to capture CO2, and thus, can mitigate these challenges. In addition, some microalgae can produce lipids suitable for biodiesel. The potential application of microalgae biomass for biofuel production is a clean and sustainable approach to replace fossil fuels. An important consideration for reducing the cost of biofuel is the economical production of algal biomass with high lipid yields. In this study, the marine microalgae Nannochloropsis gaditana were investigated for biomass and lipid production using two wastewater streams, i.e., road salt run-off and vegetable greenhouse industry effluents as the growth media using batch or fed-batch cultivation. The recovery of biomass was also investigated using coagulants or pH change. In the first phase of the research, the effect of salinity on biomass concentration and lipid production was examined in batch culture. Biomass yields of 1-2 g/L of culture were obtained with the maximum lipid of 22% (g/g) biomass in the road salt media. The crude road salt media provided all the essential micronutrients needed for algal cultivation. The fatty acid composition analysis of the obtained lipid indicated C16 and C18 as the major components (~ 45% of FAME) further confirmed the suitability of biomass generated for biofuel feed-stock. This study has established that the use of road salt containing nitrate and phosphate nutrients will support the growth marine micro algae for remediation of waste water system that are the concern at winter prevalent regions. The controlled feeding of nitrates in fed-batch cultures can be applied to promote growth and lipid production in microalgae. The fed-batch cultivation system was, therefore, next applied to provide nutrition sufficient, depletion and repletion conditions. In this study, N. gaditana was cultured in batch and fed-batch bioreactors. Three modes of nutrient feeding i.e., pulse; continuous and staged were applied under two different light regimes for autotrophic cultivation. Higher nitrates levels negatively affected the lipid production. Increasing the light intensity was found to increase the lipid content in the microalgae for all three fed-batch feeding modes. A maximum of 58.3% lipid fraction of algal dry weight was achieved when i using pulse-fed cultures at an illumination of 200μmol photons/m2/and 10mg/d nitrate feeding. This condition also resulted in the maximum lipid productivity of 44.6 mg /L/d. The fatty acid composition of the lipids consisted predominantly of long chain fatty acids (C: 16 and C: 18) and accounted for 70 % of the overall FAME. The other two feeding modes (continuous and staged) were not as effective for lipid and biomass production. This study demonstrates the applicability of pulsed feeding strategies in fed-batch cultures. In the final phase of the study, the coagulation/flocculation methods were applied to harvest the biomass from the growth media. Cell harvesting was investigated using two approaches: coagulant chemical addition and pH change. The pH value of 11 was identified as the threshold pH for the alkaline flocculation of Nannochloropsis gaditana cells in the road salt growth media. The harvesting efficiency increased to 89% at the pH 11 and above. However, the coagulant/flocculant ferric chloride provided the best flocculation with 95% harvesting efficiency and the concentration factor of 23.5. The bio-coagulant chitosan was not effective to coagulate the cells within the 60 minutes of settling time. This study primarily resulted in three main conclusions. First, the phytoremediation of road salt run-off generates the biomass suitable for biodiesel production. Secondly, the application pulsed fed-batch cultivation with nitrate feeding and increased light intensity simultaneously improves the biomass and lipid production. Finally, the alkaline induced flocculation is an effective harvesting method for the recovery of Nannochloropsis gaditana from road salt media. The study provides new directions for the integration of biofuel production with greenhouse vegetable effluent and road salt run-off and the application of marine microalgae for the treatment of hyper saline wastewater. ii Keywords Biodiesel Biofuel Biomass Coagulation Concentration factor (CF) Fatty acid methyl esters (FAME) Fed-batch cultivation Flocculation Greenhouse effluents Harvesting efficiency (HE) Marine microalgae Nannochloropsis gaditana Phycoremediation Pulsed feeding Road salt run-off iii Co-Authorship Statement The development of these chapters and manuscripts for submission were written and coauthored, the extent of the collaboration of the co-authors is stated below. The papers that are being prepared or submitted are given below. Chapter- 4 Paper 1 Growth kinetics of Nannochloropsis gaditana on road salt media Current status Submitted to the Journal of Environmental technology Roopa Devasya: Experimental design, laboratory work, analysis of results, and Paper writing. Amarjeet Bassi: Technical and theoretical advisor and corrections of several drafts and Chapter- 5 Paper 3 Investigation of feeding strategies for Fed batch cultivation systems for the biomass and lipid production from Nannochloropsis gaditana Current status Submitted to the Journal: Biotechnology progress Roopa Devasya: Experimental design, laboratory work, analysis of results, and paper writing. Amarjeet Bassi: Technical and theoretical advisor and corrections of several drafts and Chapter- 6 Paper 3 Investigation of alkaline flocculation for Nannochloropsis gaditana in the phycoremediated road salt run-off media Current status Prepared for the submission in progress Roopa Devasya: Experimental design, laboratory work, analysis of results, and paper writing. Amarjeet Bassi: Technical and theoretical advisor and corrections of several drafts and iv Acknowledgments Foremost, I would like to express my sincere gratitude to my supervisor Professor Amarjeet Bassi for his continuous support, advice, trust, and motivation. Thanks for giving me this enriching opportunity. I also want to thank my Ph.D. advisory committee for all the guidance and good advice received. Thanks to all the teachers and professors who have contributed to my professional development. They all have a special place in my life. My sincere thanks to Parmalat Canada and to my director Maria Pepe Francis, for providing the opportunity for continue my learning process. My sincere respect and thanks to Peter Van Esch, who rekindled my desire and showed the path to take the adventurous journey in the academic world. Thanks to my laboratory team, Shreyas, Mengyue, Claudio, Ahmed, Essam, Teresa, Yulin, Valerie and Leila for the good times, and all the invaluable things I have learned from you. Thanks to Erin Johnson, Brian Dennis and Souheil Afara for making research easier by having practical solutions to everyday problems. I am also very thankful to my friends who have contributed immensely to my personal development. They were always there for me when I needed them the most. Thanks to my hubby Vijay and daughters Tanvi and Raashi. You are my strength, my biggest support and motivation. Without your sacrifice and support I would not have reached to this stage. Thanks with love to my mother, my father, my brother, and my sisters. Your love has always been with me despite the thousands of miles between us. This would not be possible without you. v Table of Contents Abstract ................................................................................................................................ i Co-Authorship Statement................................................................................................... iv Acknowledgments............................................................................................................... v Table of Contents ............................................................................................................... vi List of Tables ..................................................................................................................... xi List of Figures .................................................................................................................. xiii Chapter 1 ............................................................................................................................
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