CONTROL OF PACKED-COLUMN FOULING IN THE CONTINUOUS FERMENTATION AND STRIPPING OF ETHANOL

By recycling the contents of a 14 L fermenter through a stripping colu mn to continuously remove ethanol and reduce product inhibition, conti nuous complete conversion of nutrient feed containing 600 g/L glucose was achieved in a small pilot plant. Ethanol was recovered from the ca rbon dioxide stripping gas in a refrigerated condenser, and the gas wa s reheated with steam and recycled by a blower. Productivity of ethano l in the fermentor as high as 15.8 g/L/h and condensate production of up to 10 L/day of almost 50% by volume ethanol were maintained for up to 60 days of continuous operation. Weekly washing of the column packi ng in situ was required to prevent loss of performance caused by attac hed growth of yeast cells, which restricts the gas flow rate through t he stripping column. (C) 1996 John Wiley & Sons, Inc.