A bioreactor, in the shape of a column, in which the reaction medium is kept mixed and aerated by introduction of air into the bottom (cf. air lift bioreactor).
Source:
PAC, 1992, 64, 143. 'Glossary for chemists of terms used in biotechnology (IUPAC Recommendations 1992)' on page 149 (https://doi.org/10.1351/pac199264010143)