Evaluation of Electro-Flocculation for Biomass Production of Marine Microalgae Phaodactylum tricornutum

Authors: Luciana C. Ramos, Leandro J. Sousa, Antônio Ferreira da Silva, Valéria Gomes Oliveira Falcão, Suzana T. Cunha Lima

Abstract:

The commercial production of biodiesel using microalgae demands a high-energy input for harvesting biomass, making production economically unfeasible. Methods currently used involve mechanical, chemical, and biological procedures. In this work, a flocculation system is presented as a cost and energy effective process to increase biomass production of Phaeodactylum tricornutum. This diatom is the only species of the genus that present fast growth and lipid accumulation ability that are of great interest for biofuel production. The algae, selected from the Bank of Microalgae, Institute of Biology, Federal University of Bahia (Brazil), have been bred in tubular reactor with photoperiod of 12 h (clear/dark), providing luminance of about 35 μmol photons m^-2s^-1, and temperature of 22 °C. The medium used for growing cells was the Conway medium, with addition of silica. The seaweed growth curve was accompanied by cell count in Neubauer camera and by optical density in spectrophotometer, at 680 nm. The precipitation occurred at the end of the stationary phase of growth, 21 days after inoculation, using two methods: centrifugation at 5000 rpm for 5 min, and electro-flocculation at 19 EPD and 95 W. After precipitation, cells were frozen at -20 °C and, subsequently, lyophilized. Biomass obtained by electro-flocculation was approximately four times greater than the one achieved by centrifugation. The benefits of this method are that no addition of chemical flocculants is necessary and similar cultivation conditions can be used for the biodiesel production and pharmacological purposes. The results may contribute to improve biodiesel production costs using marine microalgae.

Keywords: Biomass, diatom, flocculation, microalgae.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1130453

References:

[1] Borowitzk, L.J. (Eds). Microalgal Biotechnology. Cambridge: Cambridge University, 1993. 477p.
[2] Franco, A. L.C.; Lobo, I.P.; Cruz, R.S. Teixeira, C.M.L.T.; Neto, J.A.A.; Menezes, R.S. Biodiesel de Microalgas: Avanços e Desafios. Química Nova, v. 36 (3), p 437-438, 2013.
[3] Daboussi , F.; Leduc, S.; Dubois, A.M.; Guyot, G. V.; Perez-Michaut, C., Amato A.; Falciatore, A.; Juillerat A., Beurdeley, M. , Voytas D. F.; Cavarec, L. Duchateau, P. Genome engineering empowers the diatom Phaeodactylum tricornutum for biotechnology Nature Communications DOI: 10.1038/ncomms4831, 2013.
[4] Desbois, A.B.; Mearns-Spragg, A.; Smith V. J. A Fatty Acid from the Diatom Phaeodactylum tricornutum is Antibacterial against Diverse Bacteria Including Multi-resistant Staphylococcus aureus (MRSA) Marine Biotechnology. v. 11, p. 45–52, 2009.
[5] Lee, A.K.; Lewis, D.M.; Ashman P.J. Harvesting of marine microalgae by electroflocculation: The energetics, plant design, and economics. Applied Energy, v.108, p.45–53, 2013.
[6] Obata, T.; Fernie, A.R.; Nunes-Nesi, A. The Central Carbon and Energy Metabolism of Marine Diatoms. Metabolites, v. 3(2), p.325-346, 2013.
[7] Popko, J.; Herrfurth, C.; Feussner, K; Ischebeck, T; Iven, T; Haslam, R; Hamilton, M; Sayanova, O, Napier J, Khozin-Goldberg I, Feussner I. Metabolome Analysis Reveals Betaine Lipids as Major Source for Triglyceride Formation, and the Accumulation of Sedoheptulose during Nitrogen-Starvation of Phaeodactylum tricornutum. PLoS One. Oct 13;11(10):e0164673. doi: 10.1371/journal.pone.0164673. eCollection 2016.
[8] Nascimento, I.A.; Santos, J.N.; Nascimento, T.P.; Leite, M.B.; Martins, F.M. Título: Fotobiorreator Tubular Vertical Para Produzir Microalgas. Patente: Privilégio de Inovação. Número do registro: 0000221105500270. Depósito: 30/05/2011. INPI.
[9] Lourenço, S.O. Cultivo de microalgas marinhas: princípios e aplicações. São Carlos: Rima, 2006.
[10] Levasseur, M.; Thompson P. A.; Harrison, P. J. Physiological Acclimation of Marine Phytoplankton to Different Nitrogen Sources. Journal of Phycology. v. 29 (5). p. 587-595, 1993.
[11] Salim, S.; Shi, Z; Vermuë, M.H.; Wijffels, R.H. Effect of growth phase on harvesting characteristics, autoflocculation and lipid content of Ettlia texensis for microalgal biodiesel production. Bioresource Technology p. 214–221, 2013.
[12] Nascimento, I.A.; Dominguez, I.T.C.; Santos, J.N.; Nascimento M.A.; Sousa, L.; Sansone G. Biodiesel yields and fuel quality as criteria for algal-feedstock selection: Effects of CO2-supplementation and nutrient levels in cultures. Algal Research, p. 53–60. 2015.
[13] Xiong, Q.; Pang, Q.; Pan, X.; Chika, A. O.; Wang, L.; Shi J.; Jia L,; Chen, C.; Gao Y. Facile sand enhanced electro-flocculation for cost-efficient harvesting of Dunaliella salina. Bioresource Technology v. 187, p. 326–330, 2015.
[14] Shi, W.; Zhu L.; Chen Q.; Luc, J. Pan, G.; Hu L.; Yi, Q. Synergy of flocculation and flotation for microalgae harvesting using aluminium electrolysis. Bioresource Technology v. 233, p. 127–133. 2017.
[15] Wong, Y. K.; Ho, Y.M.; Leung, H.M.; Ho, K.C.; Yau, Y.H.; Yung, K.K.L. Enhancement of Chlorella vulgaris harvesting via the electro-coagulation-flotation (ECF) method. Environmental Science and Pollution Research DOI 10.1007/s11356-016-7856-x. 2016.
[16] Chauton, M.S.; Olsen, Y.; Vadstein, O. Biomass production from the microalga Phaeodactylum tricornutum: Nutrient stress and chemical composition in exponential fed-batch cultures. Biomass and Bioenergy 58 (2013) 87-94, 2013.
[17] Chisti, Y. Biodiesel from microalgae. Biotechnology Advances, v. 25, n. 3, p. 294-306, 2007.