Treatment of make-up water for use in a fermentation process for growth of yeast cells requiring growth factors

In a process for aqueous biological fermentation employing at least one yeast or bacterial culture wherein said microorganism requires at least one organic growth factor for effective growth under aqueous aerobic fermentation conditions employing at least one organic growth factor, make-up water containing residual chlorine and a suitable carbon substrate, assimilable nitrogen source, molecular oxygen, and nutrient minerals, effective for growth of said at least one yeast or bacterial culture, said residual chlorine being present in amounts rendering said at least one growth factor less effective for growth of the microorganism, the step which comprises substantially removing said residual chlorine from said residual chlorine-containing make-up water to produce a residual chlorine content in said water of substantially zero prior to contact with said organic growth factors, said residual chlorine being removed by one treatment selected from the group consisting of using a reducing agent, aeration and a combination of heating and aeration, said treatment effective to render said residual chlorine content substantially zero.