Ethanol production from whey permeate in a continuous anaerobic bioreactor by Kluyveromyces marxianus

Abstract

The possibility of using whey permeate as a raw material for the production of ethanol by continuous fermentation by using Kluyveromyces marxianus was examined. The ethanol formation was investigated as a function of the hydraulic retention time in a UASB reactor. The initial lactose concentration in permeate was 50.0 g L⁻¹. The hydraulic retention time supplied were 12, 24, 48 h and the daily ethanol formations were 4.46, 8.61, 7.73 g L⁻¹, respectively. The yield coefficient of ethanol was 0.089 g ethanol g⁻¹ lactose when the hydraulic retention time was 12 h and raised to 0.325 g g⁻¹ when the hydraulic retention time was as long as 48 h. The results indicated that in ethanol fermentation the hydraulic retention time should be 24 h to obtain high rates of ethanol formation and to avoid product inhibition.

Keywords:

• continuous fermentation
• ethanol fermentation
• whey permeate
• lactose
• Kluyveromyces marxianus

Acknowledgements

This study was supported by grant N523 049 32/1753 from the Ministry of Science and Higher Education in 2007–2008. We wish to express thanks to Dr. Małgorzata Lewandowska, Chair of Food Biotechnology, University of Warmia and Mazury in Olsztyn, Poland, for help in this study.