In ethanol fermentation, tapered columns facilitate the liberation of CO2 and, since the bed expands through a larger cross-sectional area, smaller pressure drops occur. In this work, 0-degrees, 2-degrees, and 4-degrees tapered columns, containing Saccharomyces cerevisiae entrapped in beads of kappa-carrageenan, were operated for continuous production of ethanol from glucose. The column inlet diameters and the bead volume were maintained constant for the three columns. With decreasing taper angle, increasing feed glucose concentration, increasing feed flow rate and increasing bead volume in the reactor, the pressure drop across the bed increased. There was no significant difference between the ethanol productivities obtained in the 0-degrees, 2-degrees, and 4-degrees tapered columns when a packed volume of 52% of the total volume was examined. Increasing the packed volume to 84% of the total caused the cylindrical column to become inoperable due to pressure buildup and bead compression. When the columns were packed to 84% capacity, the productivity and pressure drop values obtained on the 2-degrees and 4-degrees tapered columns did not significantly differ. For a feed concentration of 150 g glucose dm-3 and a residence time range of 5.4-15.94 h, the pressure drop varied between 4.5 x 10(3) and 1.28 x 10(4) Pa in the 2-degrees and between 4 x 10(3) and 7.98 x 10(3) Pa in the 4-degrees tapered column. Conversion in the 2-degrees tapered column varied from 94% to 78.8% and in the 4-degrees tapered column from 92.6% to 78.8%. Defining optimum taper angle as the smallest angle which allows for stable operation without any pressure buildup, the taper angle of 2-degrees was selected as nearest to the optimum value.