Bench-top scale (I litre) and pilot scale (1000 litre) alcohol fermentations were carried out in a packed-bed external circulating reactor using the mash of dried sweet potato with its dregs as substrates and yeast entrapped in modified calcium alginate thin gel slices. Fermentation activity in the bioreactors was stable with high fermentation activity maintained for more than three months and six months, respectively. Alcohol productivity (specific alcohol production rate) for the two bioreactors was 9.8 g (EtOH)/l(bed). h and 9.2 g (EtOH)/l(bed). h. Starch utilisation rate was about 90%. The multiplication kinetics of immobilised yeast cells were recorded