Reactor temperature was maintained at 309
0.2°C. A variable speed peristaltic pump (Watson–
Marlow, model MHRE 22) was used to
feed the reactor. Nitrogen gas was flushed from
the bottom of the reactor at a flow rate of 1 l
h1 in order to facilitate CO2 removal, to improve
the ethanol productivity. The pH was constant
in the reactor. Dilution rates ranging from
0.2 to 2.5 h1 were evaluated and then run at a
dilution rate of 1 h1 for 87 days to determine
the operational stability. Following fermentation
the concentrations of ethanol, and sugars in the
exit stream was measured.