Advertisement

Journal of Applied Phycology

, Volume 15, Issue 2–3, pp 143–153 | Cite as

Ultrasound, a new separation technique to harvest microalgae

  • Rouke Bosma
  • Wim A. van Spronsen
  • Johannes Tramper
  • René H. Wijffels
Article

Abstract

In this article it is proven that ultrasound can be used to harvest microalgae. The separation process is based on gentle acoustically induced aggregation followed by enhanced sedimentation. In this paper, the efficiency of harvesting and the concentration factor of the ingoing biomass concentration are optimized and the relevance of this process compared to other harvesting processes is determined. For the optimisation, five parameters were modeled simultaneously by the use of an experimental design. An experimental design was chosen, because of possible interaction effects between the different parameters. The efficiency of the process was modeled with a R-squared of 0.88. The ingoing flow rate and the biomass concentration had a lot of influence on the efficiency of the process. Efficiencies higher than 90% were reached at high biomass concentrations and flow rates of 4–6 L day−1. At most, 92% of the organisms could be harvested and a concentration factor of 11 could be achieved at these settings. It was not possible to harvest this microalga with higher efficiencies due to its small size and its small density difference with water. The concentration factor of the process was modeled with a R-squared of 0.75. The ingoing flow rate, biomass concentration and ratio between harvest flow and ingoing flow rate had a significant effect on the concentration factor. Highest concentration factors, up to 20, could be reached at low biomass concentrations and low harvest flows. On industrial scale, centrifuges can better be used to harvest microalgae, because of lower power consumption, better efficiencies and higher concentration factors. On lab- or pilot-plant scale, an ultrasonic harvesting process has the advantages that it can be operated continuously, it evokes no shear stress and the occupation space is very small. Also, when the algae excrete a soluble high valued product this system can be used as a biofilter.

Cell filtration Continuous flow Experimental design Microalgae Optimisation Separation process Technique Ultrasonic wave Ultrasound 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Bierau H., Perani A., Al-Rubeai M. and Emery A.N. 1998. A comparison of intensive cell culture bioreactors operating with Hybridomas modified for inhibited apoptotic response. J. Biotechnol. 62: 195-207.Google Scholar
  2. Coakley W.T., Hawkes J.J., Sobanski M.A., C ousins C.M. and Spengler J. 2000. Analytical scale ultrasonic standing wave manipulation of cells and microparticles. Ultrasonics 38: 638-641.Google Scholar
  3. Doblhoff-Dier O., Gaida T. and Katinger H. 1994. A novel ultrasonic resonance field device for the retention of animal cells. Biotechnol. Progr. 10: 428-432.Google Scholar
  4. Gröschl M. 1998. Ultrasonic Separation of Suspended Particles - Part I: Fundamentals. Acust. Acta Acust. 84: 432-447. Gröschl M., Burger W., Handl B.Google Scholar
  5. Doblhoff-Dier O., Gaida T. and Schmatz C. 1998. Ultrasonic Separation of Suspended Particles - Part III: Application in Biotechnology. Acust. Acta. Acust. 84: 815-822.Google Scholar
  6. Haaland P.D. 1989. Experimental Design in Biotechnology. Marcel Dekker Inc., New York and Basel, 259 pp.Google Scholar
  7. Hawkes J.J. and Coakley W.T. 1996. A continuous flow ultrasonic cell-filtering method. Enzyme Microb. Technol. 19: 57-62.Google Scholar
  8. Hawkes J.J., Limaye M.S. and Coakley W.T. 1997. Filtration of bacteria and yeast by ultrasound-enhanced sedimentation. J. appl. Microbiol. 82: 39-47.Google Scholar
  9. Kashyap S., Sundararajan A. and Lu-Kwang J. 1998. Flotation characteristics of cyanobacterium Anabaena flos-aquae for gas vesicle production. Biotechnol. Bioengng. 60: 636-641.Google Scholar
  10. Kilburn D.G., Clarke D.J., Coakley W.T. and Bardsley D.W. 1989. Enhanced sedimentation of mammalian cells following acoustic aggregation. Biotechnol. Bioengng. 34: 559-562.Google Scholar
  11. Kubitschek H.E. 1984. Independence of buoyant cell density and growth rate in Escherichia coli. J. Bact. 158: 296-299.Google Scholar
  12. Kubitschek H.E. 1987. Buoyant density variation during the cell cycle in microorganisms. Crit. Rev. Microbiol. 14: 73-97.Google Scholar
  13. Myers R.H. and Montgomery D.C. 1995. Response Surface Methodology: Process and Product Optimization Using Designed Experiments. John Wiley & Sons, New York, NY, USA.Google Scholar
  14. Rippka R., Deruelles J., Waterbury J.B., Herdman M. and Stanier R.Y. 1979. Generic assignments, strain histories and properties of pure cultures of cyanobacteria. J. gen. Microbiol. 111: 1-61.Google Scholar
  15. Ryll T., Dutina G., Reyes A., Gunson J., Krummen L. and Etcheverry T. 2000. Performance of small-scale CHO perfusion cultures using an acoustic cell filtration device for cell retention: Characterization of separation efficiency and impact of perfusion on product quality. Biotechnol. Bioengng. 69: 440-449.Google Scholar
  16. Spengler J. and Jekel M. 2000. Ultrasound conditioning of suspensions - studies of streaming influence on particle aggregration on a lab-and pilot-plant scale. Ultrasonics 38: 624-628.Google Scholar
  17. Trampler F., Sonderhoff S.A., Pui P.W.S., Kilburn D.G. and Piret J.M. 1994. Acoustic cell filter for high density perfusion culture of hybridoma cells. Bio/Technology 12: 281-284.Google Scholar
  18. Van den Berg H., Oudshoorn A., Trampler F. and Keijzer T. 2001. High density cell cultures in perfusions. A perspective for vaccine production? BIOforum International 5: 37-38.Google Scholar
  19. Winkelmeier P., Glauner B. and Lindl T. 1993. Quantification of cytotoxicity by cell volume and cell profileration. ATLA 21: 269-280.Google Scholar
  20. Zhang J., Collins A., Chen M., Knyazev I. and Gentz R. 1998. High-Density Perfusion Culture of Insect Cells with a BioSep Ultrasonic Filter. Biotechnol. Bioengng. 59: 351-359.Google Scholar

Copyright information

© Kluwer Academic Publishers 2003

Authors and Affiliations

  • Rouke Bosma
    • 1
  • Wim A. van Spronsen
    • 1
  • Johannes Tramper
    • 1
  • René H. Wijffels
    • 1
  1. 1.Food and Bioprocess Engineering Group, Department of Agrotechnology and Food SciencesWageningen UniversityWageningenThe Netherlands

Personalised recommendations