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Cultivation of E. coli in single‐ and ten‐stage tower–loop reactors
Author(s) -
Adler I.,
Schügerl K.
Publication year - 1983
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260250210
Subject(s) - continuous stirred tank reactor , bioreactor , tower , substrate (aquarium) , mass transfer , loop (graph theory) , chemistry , analytical chemistry (journal) , chromatography , materials science , mathematics , biology , engineering , ecology , civil engineering , organic chemistry , combinatorics
E. Coli was cultivated in batch and continuous operations in the presence of an antifoam agent in stirred‐tank and in single‐ and ten‐stage airlift tower reactors with an outer loop. The maximum specific growth rate, μ m , the substrate yield coefficient, Y x / s , the respiratory quotient, RQ, substrate conversion, U s , the volumetric mass transfer coefficient, K L a , the specific interfacial area, a , and the specific power input, P / V L , were measured and compared. If a medium is used with a concentration of complex substrates (extracts) 2.5 times higher than that of glucose, a spectrum of C sources is available and cell regulation influences reactor performance. Both μ m and Y X / S , which were evaluated in batch reactors, cannot be used for continuous reactors or, when measured in stirred‐tank reactors, cannot be employed for tower‐loop reactors: μ m is higher in the stirred‐tank batch than in the tower‐loop batch reactor, μ m and Y x / s are higher in the continuous reactor than in the batch single‐stage tower–loop reactor. The performance of the single‐stage is better than that of the ten‐stage reactor due to the inefficient trays employed. A reduction of the medium recirculation rate reduces OTR, U s , Pr, and Y X / S and causes cell sedimentation and flocculation. The volumetric mass transfer coefficient is reduced with increasing cultivation time; the Sauter bubble diameter, d s , remains constant and does not depend on operational conditions. An increase in the medium recirculation rate reduces k L a . The specific power input, P / V L , for the single‐stage tower loop is much lower with the same k L a value than for a stirred tank. The relationship k L a vs. P / V L evaluated for model media in stirred tanks, can also be used for cultivations in these reactors.