Influence of the nutrient concentrations of whey on ethanol and biomass production and COD reduction

The present study aimed at the use of cheese whey as substrate for ethanol production by Kluyveromyces marxianus. The effect of the initial cheese whey concentration (M1 57.60; M2 45.60; M3 32.50 and M4 18.80 g L-1) on the alcoholic fermentation was studied. After sterilization, the in natura media were incubated at 30 degrees C for 48 hours, and then lactose, protein, ethanol, cell growth and chemical oxygen demand were analyzed. According to the results, M1 medium (the highest concentration) showed a greater production and volumetric productivity of ethanol 16.90 and 1.26 g L-1 hour(-1), respectively, and resulted in the greatest cell production and volumetric productivity of 5.80 and 0.40 g L-1 hour(-1), respectively. However, in terms of ethanol yield, the most satisfactory result was obtained using the M3 medium, pro 82.30% in 12 hours of fermentation. With respect to the COD, the organic substance content of M4 medium was reduced by 82.28%.