High speed, consecutive batch or continuous, low effluent process for the production of ethanol from molasses, starches, or sugars

A method of developing an improved strain of Saccharomyces cerevisae which comprises a) a selecting a highly flocculent strain of that species, b) running a continuous single stage CSTR for a period of weeks, c) selecting, based on floc stability, a ‘best’ pellet, d) using this pellet as a starting inoculation for running a second CSTR, e) repeating steps b), c) and d) until an obtained stable well shaped floc cell mass is capable of maintaining consistent performance over a period of time, f) improving the osmo-tolerance of the stable floc mutant obtained from step d) by growing a small pellet thereof in a high-salt medium, g) taking a single pellet from the resulting medium and growing it again in fresh medium, h) repeating steps f) and g) a number of times until a new, highly flocculent, stable, osmo-tolerant mutant strain of Saccharomyces cerevisae is obtained.