NOVELTY - Generating (M1) sugar from biomass, comprises: contacting the biomass with enzymes under conditions suitable to hydrolyze components of the biomass to sugars, thus producing a mixture of solids, liquids, and sugars; separating the mixture into a liquid phase containing sugars and a solids phase; incubating the solids phase under conditions suitable to hydrolyze components of solid phase to sugars; separating liquid phase into a permeate comprising dissolved solids and sugars and a retentate comprising e.g. undissolved solids; and combining the washed retentate with biomass or solids phase.    USE - The method is useful for generating sugar from biomass, where the sugars are useful to produce ethanol (all claimed).    ADVANTAGE - The method economically provides increased yields of carbohydrates and fermentable sugars with out increasing the solids concentration to undesired levels.    DETAILED DESCRIPTION - Generating (M1) sugar from biomass, comprises: contacting the biomass with enzymes under conditions suitable to hydrolyze components of the biomass to sugars, thus producing a mixture of solids, liquids, and sugars; separating the mixture into a liquid phase containing sugars and a solids phase; incubating the solids phase under conditions suitable to hydrolyze components of the solid phase to sugars, thus producing additional sugars; separating the liquid phase into a permeate comprising dissolved solids and sugars and a retentate comprising undissolved solids, enzymes, and sugars; and combining the washed retentate with the biomass or solids phase under conditions where the biomass is converted to sugars. INDEPENDENT CLAIMS are also included for:    (1) generating (M2) sugar from biomass, comprising: contacting the biomass with enzymes under conditions suitable to hydrolyze components of the biomass to sugars, thus producing a mixture of solids, liquids, and sugars; separating the mixture into a liquid phase and a solids phase; and combining the washed solids phase with the biomass under conditions where the biomass is converted to additional sugars; and    (2) a system for treating biomass, comprising: a first auger comprising a solids inlet, a screw inside the auger to direct a solid mass in the auger from a first end to a second end, a liquid outlet at the first end, a solids outlet at the second end, and a separator suitable for separating the biomass into a liquid phase and a solids phase and positioned between the liquid outlet and the screw and the solids outlet; and a second auger comprising an inlet in fluid communication with the solids outlet for receiving a solids mass from the first auger, and a solids outlet.