Abstract: A process for the continuous production of fermentation alcohol, by effecting fermentation of a continuous or substantially continuous supply of the liquid substrate by a dense suspension of a suitable micro-organism in a reaction column wherein the suspension is maintained in a well mixed state. The mixture passes from the upper region of the reaction column into a degassing zone where less turbulent conditions readily permit degassing of the mixture, causing part of the degassed mixture to flow into a settling zone wherein quiescent conditions permit the biomass to settle out. The settled biomass is returned to the bottom of the reaction column to assist in the continuation of the fermentation process. Gases evolving from the top of the reaction column and from the tops of the degassing and settling zones are removed.