Gas hold-up and oxygen mass transfer in three pneumatic bioreactors operating with sugarcane bagasse suspensions

• Published in: Bioprocess and biosystems engineering Vol. 37; no. 5; pp. 805 - 812
• Main Authors: Esperança, M. N., Cunha, F. M., Cerri, M. O., Zangirolami, T. C., Farinas, C. S., Badino, A. C.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2014; Springer Nature B.V
• Subjects: Air flow; Bagasse; Bioengineering; Bioreactors; Biotechnology; Cellulose; Cellulose - chemistry; Chemistry; Chemistry and Materials Science; Environmental Engineering/Biotechnology; Enzymes; Flow rates; Food Science; Industrial and Production Engineering; Industrial Chemistry/Chemical Engineering; Mass transfer; Membrane reactors; Models, Theoretical; Original Paper; Oxygen; Oxygen - chemistry; Oxygen transfer; Particle size; Saccharum - chemistry; Sugarcane; Oxygen transfer; Bubble columns; Airlift bioreactors; Gas hold-up; Sugarcane bagasse
• ISSN: 1615-7591; 1615-7605
• DOI: 10.1007/s00449-013-1049-5

Sugarcane bagasse is a low-cost and abundant by-product generated by the bioethanol industry, and is a potential substrate for cellulolytic enzyme production. The aim of this work was to evaluate the effects of air flow rate ( Q AIR ), solids loading (% S ), sugarcane bagasse type, and particle size on the gas hold-up ( ε G ) and volumetric oxygen transfer coefficient ( k L a ) in three different pneumatic bioreactors, using response surface methodology. Concentric tube airlift (CTA), split-cylinder airlift (SCA), and bubble column (BC) bioreactor types were tested. Q AIR and  % S affected oxygen mass transfer positively and negatively, respectively, while sugarcane bagasse type and particle size (within the range studied) did not influence k L a . Using large particles of untreated sugarcane bagasse, the loop-type bioreactors (CTA and SCA) exhibited higher mass transfer, compared to the BC reactor. At higher  % S , SCA presented a higher k L a value (0.0448 s −1 ) than CTA, and the best operational conditions in terms of oxygen mass transfer were achieved for  % S  < 10.0 g L −1 and Q AIR  > 27.0 L min −1 . These results demonstrated that pneumatic bioreactors can provide elevated oxygen transfer in the presence of vegetal biomass, making them an excellent option for use in three-phase systems for cellulolytic enzyme production by filamentous fungi.