TECHNOLOGY FOCUS - BIOLOGY - Preferred Components: The ethanol containing biomass mixture is derived from an initial biomass feedstock comprising citrus waste.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The distillation column in step (c) and step (j) is a stripping column packed with distillation trays capable of handling high-solids or high viscosity feeds.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The solid-liquid separation pretreatment step is performed on the initial ethanol-containing biomass mixture to remove at least a portion of the solids contained in it prior to the ethanol-containing biomass mixture's separation in step (a). The initial ethanol-containing biomass mixture is heated prior to the solid-liquid separation. The step (a) and step (h) are carried out in a flash vaporization unit. The steam is introduced into the vaporization unit to assist in the stripping of ethanol. The overhead stream from step (b) or (c), or from step (i) or (j), is utilized as the steam for a previous separation stage. The vacuum system is employed to assist the separation of ethanol in at least steps (a), (b) or (c), or steps (h), (i) or (j). Preferred Components: The overhead aqueous ethanol streams fed to the distillation column in step (d) and step (h) have a combined initial ethanol concentration of at least 20 wt.% of the combined streams. The initial ethanol-containing biomass mixture has a viscosity of 500-20000 (preferably 1000-10000) cP. EXAMPLE - The fermented citrus waste biomass was hydrolyzed with enzymes and fermented to give ethanol content. The pre-heated beer has a viscosity of approximately 10000 cP and a solids content of approximately 12%, which was envisaged to pre-heat with a 200 proof condenser (i.e. the thermal energy in the alcohol stream after the molecular sieves). The beer feed rate wass approximately 146000 lbs/hour. The total steam used was approximately 25000 lbs/hour and other than thermal losses, the thermal energy was available for use or capture by later stages. The majority of the energy was in the ethanol/water vapor stream and was utilized in the rectifier column, the remainder was in the stillage output, which will be at approximately 200 degrees F and was recovered using a spiral heat exchanger, or its equivalent. The base loss (ethanol in the stillage) was 0.4 wt.%. The ethanol/water stream comprised approximately 18000 lbs/hour of steam and 6000 lbs/hour of ethanol vapor and gives an ethanol/water stream of approximately 64 proof, or 32% ethanol by volume, suitable for rectification to 190 proof, or 95% ethanol.