The impact of mixing on the promotion of microorganism growth rate has been analyzed using a multiphase forced-circulation pipe-loop reactor model capable of identifying conditions under which it is possible to convert natural gas into Single-Cell Protein. The impact of mixing in the interphase mass transfer was found to exert a critical role in determining the overall productivity of the bioreactor, particularly at the high cell loadings needed to reduce the capital costs associated with the large-scale production needed for the production of relatively low-value SCP in a sustainable manner. 1. Introduction Industrial biotechnology uses living cells or cellcomponents (yeast, moulds, bacteria, plants, and enzymes) to synthesize products that are easily degradable, require less energy to produce, and create less waste during their production, all of which helps to decrease the environmental impact of this promising manufacturing approach. It is already used to generate large quantities of biobased products in sectors such as: chemicals, food and feed, detergents, pulp and paper, health care, textiles, bioenergy (e.g., biofuels, biogas), photocatalytic algae production, wastewater treatment, bioleaching, and biological site remediation. It also holds the promise of being a credible method for the sustainable development of many other products because it uses renewable raw materials and is capable of achieving very high efficiencies while converting nonrenewable resources to final products with minimum generation of undesirable byproducts/waste. Nevertheless, the shift to the bioprocessing route will happen only if the economic process and market demands justify the transition. However, the growing environmental pressures combined with the rapid developments in the science supporting biotechnology (sequencing of industrial bacterial and yeast genomes, metabolic engineering, bioinformatics and computer-based modeling, and process optimization) are opening up opportunities for new products and cost reductions. One of the main factors affecting the economic viability of many of the aforementioned operations is the rate at which interphase mass transfer can take place since it is often the parameter limiting the growth rates of microorganisms encountered in many of these biotechnological processes [1–5]. The use of forced-circulation loop reactors holds the promise of overcoming such limitations in a cost-effective fashion particularly for large-scale operations [6–11]. Whereas the achievement of high productivity is usually not a high priority issue in the
References
[1]
J. C. Merchuk and J. A. Asenjo, “The maned equation and mass transfer,” Biotechnology and Bioengineering, vol. 45, no. 1, pp. 91–94, 1995.
[2]
OECD, The Application of Biotechnology to Industrial Sustainability, OECD Publications, Paris, France, 2001.
[3]
C. U. Ugwu, J. C. Ogbonna, and H. Tanaka, “Improvement of mass transfer characteristics and productivities of inclined tubular photobioreactors by installation of internal static mixers,” Applied Microbiology and Biotechnology, vol. 58, no. 5, pp. 600–607, 2002.
[4]
P. L. Rogers, Y. J. Jeon, and C. J. Svenson, “Application of biotechnology to industrial sustainability,” Process Safety and Environmental Protection, vol. 83, no. 6B, pp. 499–503, 2005.
[5]
J. Villadsen, “Innovative technology to meet the demands of the white biotechnology revolution of chemical production,” Chemical Engineering Science, vol. 62, no. 24, pp. 6957–6968, 2007.
[6]
M. Gavrilescu, R. V. Roman, and R. Z. Tudose, “Hydrodynamics in external-loop airlift bioreactors with static mixers,” Bioprocess Engineering, vol. 16, no. 2, pp. 93–99, 1997.
[7]
H. Eriksen, K. Strand, and L. Jorgenson, “Method of fermentation,” GB Patent 0120025.2, Assigned to Statoil, Stavanger Norway, 2001.
[8]
E. B. Larsen, “U-shaped and/or nozzle U-loop fermentor and method of carrying out a fermentation process,” US Patent 6, 492, 135, 2002.
[9]
A. M. Al Taweel, J. Yan, F. Azizi, D. Odedra, and H. G. Gomaa, “Using in-line static mixers to intensify gas-liquid mass transfer processes,” Chemical Engineering Science, vol. 60, no. 22, pp. 6378–6390, 2005.
[10]
F. Yazdian, S. A. Shojaosadati, M. Nosrati, M. R. Mehrnia, and E. Vasheghani-Farahani, “Study of geometry and operational conditions on mixing time, gas hold up, mass transfer, flow regime and biomass production from natural gas in a horizontal tubular loop bioreactor,” Chemical Engineering Science, vol. 64, no. 3, pp. 540–547, 2009.
[11]
D. F. Olsen, J. B. Jorgensen, J. Villadsen, and S. B. Jorgensen, “Optimal operating points for SCP production in the U-loop reactor,” in Proceedings of the 9th International Symposium on Dynamics and Control of Process Systems (DYCOPS '10), M. Kothare, M. Tade, A. Vande Wouwer, and I. Smets, Eds., Leuven, Belgium, July 2010.
[12]
A. Amanullah, B. C. Buckland, and A. W. Nienow, “Mixing in the fermentation and cell culture industries,” in Handbook of Industrial Mixing Science and Practice, E. L. Paul, V. A. Atiemo-Obeng, and S. M. Kresta, Eds., John Wiley & Sons, New York, NY, USA, 2004.
[13]
M. Douaire, J. Morchain, and A. Liné, “Mini review: relationship between hydrodynamic conditions and substrate influx toward cells,” in Proceedings of the 13th European Conference on Mixing, London, UK, April 2009.
[14]
Y. K. Lee, “Microalgal mass culture systems and methods: their limitation and potential,” Journal of Applied Phycology, vol. 13, no. 4, pp. 307–315, 2001.
[15]
B. H. Um and Y. S. Kim, “Review: a chance for Korea to advance algal-biodiesel technology,” Journal of Industrial and Engineering Chemistry, vol. 15, no. 1, pp. 1–7, 2009.
[16]
C. Y. Chen, K. L. Yeh, R. Aisyah, D. J. Lee, and J. S. Chang, “Cultivation, photobioreactor design and harvesting of microalgae for biodiesel production: a critical review,” Bioresource Technology, vol. 102, no. 1, pp. 71–81, 2011.
[17]
A. Heyouni, M. Roustan, and Z. Do-Quang, “Hydrodynamics and mass transfer in gas-liquid flow through static mixers,” Chemical Engineering Science, vol. 57, no. 16, pp. 3325–3333, 2002.
[18]
I. Reynolds, “Laboratory protocol PI,” in Proceedings of the 14th Process Intensification Network Meeting, BHR Group, Cranfield UK, November 2002.
[19]
B. Weyand, M. Israelowitz, H. von Schroeder, and P. Vogt, “Fluid dynamics in bioreactor design: considerations for the theoretical and practical approach,” in Bioreactor Systems for Tissue Engineering, C. Kasper, M. van Griensven, and R. Portner, Eds., pp. 251–268.
[20]
R. Munter, “Comparison of mass transfer efficiency and energy consumption in static mixers,” Ozone: Science & Engineering, vol. 32, no. 6, pp. 399–407, 2010.
[21]
A. Arwa, S. Baup, N. Gondrexon, J. P. Magnin, and J. Willison, “Enhancement of mass transfer characteristics and phenanthrene degradation in a two-phase partitioning bioreactor equipped with internal static mixers,” Biotechnology and Bioprocess Engineering, vol. 16, no. 2, pp. 413–418, 2011.
[22]
C. Zhong and Y. J. Yuan, “Responses of Taxus cuspidata to hydrodynamics in bubble column bioreactors with different sparging nozzle sizes,” Biochemical Engineering Journal, vol. 45, no. 2, pp. 100–106, 2009.
[23]
S. Schmalzriedt, M. Jenne, K. Mauch, and M. Reuss, “Integration of physiology and fluid dynamics,” Advances in Biochemical Engineering/Biotechnology, vol. 80, pp. 19–68, 2003.
[24]
F. Garcia-Ochoa and E. Gomez, “Bioreactor scale-up and oxygen transfer rate in microbial processes: an overview,” Biotechnology Advances, vol. 27, no. 2, pp. 153–176, 2009.
[25]
C. Lu, F. G. Acién Fernández, E. Ca？izares Guerrero, D. O. Hall, and E. Molina Grima, “Overall assessment of Monodus subterraneus cultivation and EPA production in outdoor helical and bubble column reactors,” Journal of Applied Phycology, vol. 14, no. 5, pp. 331–342, 2002.
[26]
A. H. Scragg, A. M. Illman, A. Carden, and S. W. Shales, “Growth of microalgae with increased calorific values in a tubular bioreactor,” Biomass and Bioenergy, vol. 23, no. 1, pp. 67–73, 2002.
[27]
F. Yazdian, M. P. Hajiabbas, S. A. Shojaosadati, M. Nosrati, E. Vasheghani-Farahani, and M. R. Mehrnia, “Study of hydrodynamics, mass transfer, energy consumption, and biomass production from natural gas in a forced-liquid vertical tubular loop bioreactor,” Biochemical Engineering Journal, vol. 49, no. 2, pp. 192–200, 2010.
[28]
R. K. Thakur, C. Vial, K. D. P. Nigam, E. B. Nauman, and G. Djelveh, “Static mixers in the process industries—a review,” Chemical Engineering Research and Design, vol. 81, no. 7, pp. 787–826, 2003.
[29]
L. Oshinowo and D. C. S. Kuhn, “Turbulence decay behind expanded metal screens,” Canadian Journal of Chemical Engineering, vol. 78, no. 6, pp. 1032–1039, 2000.
[30]
F. Azizi and A. M. Al Taweel, “Population balance simulation of gas-liquid contacting,” Chemical Engineering Science, vol. 62, no. 24, pp. 7436–7445, 2007.
[31]
A. W. M. Roes, A. J. Zeeman, and F. H. J. Bukkems, “High intensity gas/liquid mass transfer in the bubbly flow region during co-current upflow through static mixers,” vol. 87 of Institution of Chemical Engineers Symposium Series, pp. 231–238, 1984.
[32]
I. Turunen and H. Haario, “Mass transfer in tubular reactors equipped with static mixers,” Chemical Engineering Science, vol. 49, no. 24, pp. 5257–5269, 1994.
[33]
A. R. Toader, P. Hamersma, and R. F. Mudde, “Mass transfer in static mixers,” in Proceedings of the 10th International Gas Liquid Solid Reactor Engineering Conference, Praga, Portugal, June 2011.
[34]
F. Azizi and A. M. Al Taweel, “Intensifying gas-liquid mass transfer operations,” in Proceedings of the 8th European Congress of Chemical Engineering, Berlin, Germany, September 2011.
[35]
G. Hebrard, J. Zeng, and K. Loubiere, “Effect of surfactants on liquid side mass transfer coefficients: a new insight,” Chemical Engineering Journal, vol. 148, no. 1, pp. 132–138, 2009.
[36]
T. Lemenand, P. Dupont, D. Della Valle, and H. Peerhossaini, “Turbulent mixing of two immiscible fluids,” Journal of Fluids Engineering, Transactions of the ASME, vol. 127, no. 6, pp. 1132–1139, 2005.
[37]
C. Israelidis, “Nutrition—Single Cell Protein, Twenty Years Later,” 2006, http://www.biopolitics.gr/BIOPOLITICS/HTML/PUBS/VOL1/isreali.htm.
[38]
K. Rostami, M. T. Moazed, D. Zareh, and A. Kheirolomoom, “Single cell protein production using airlift reactor containing static mixer,” in Journal of Bioscience and Bioengineering, vol. 108, pp. 1389–1723, 2009.
[39]
J. Nielsen, J. Villadsen, and G. Liden, Bioreaction Engineering Principles, Kluwer Academic/Plenum Publishers, 2003.
[40]
L. Joergensen and H. Degn, “Growth rate and methane affinity of a turbidostatic and oxystatic continuous culture of Methylococcus capsulatus (Bath),” Biotechnology Letters, vol. 9, no. 1, pp. 71–76, 1987.
[41]
K. S. Jun and S. C. Jain, “Oxygen transfer in bubbly turbulent shear flow,” Journal of Hydraulic Engineering, vol. 119, no. 1, pp. 21–36, 1993.
[42]
K. Podila, A. M. Al Taweel, M. Koksal, A. Troshko, and Y. P. Gupta, “CFD simulation of gas-liquid contacting in tubular reactors,” Chemical Engineering Science, vol. 62, no. 24, pp. 7151–7162, 2007.
[43]
J. Klein, J. Maia, A. A. Vicente, L. Domingues, J. A. Teixeira, and M. Jura？？ík, “Relationships between hydrodynamics and rheology of flocculating yeast suspensions in a high-cell-density airlift bioreactor,” Biotechnology and Bioengineering, vol. 89, no. 4, pp. 393–399, 2005.
