NOVELTY - Producing a concentrated sugar solution from a biomass, comprises: (a) delignifying the biomass by e.g. (i) contacting the biomass with water and at least one nucleophilic base to form a biomass slurry, where the slurry comprises a lignin-containing liquid fraction and a solid fraction comprising a polysaccharide enriched biomass; (b) contacting the solid fraction of the polysaccharide enriched biomass with an aqueous acid solution to produce an intermediate saccharification product; and (c) contacting the intermediate saccharification product with a saccharification enzyme consortium.    USE - The method is useful for producing a concentrated sugar solution from a biomass, where the biomass is: cellulosic or lignocellulosic material including bioenergy crops, agricultural residues, municipal solid waste, industrial solid waste, yard waste, wood and/or forestry waste; and corn grain, corn cobs, crop residues such as corn husks, corn stover, grasses, wheat, wheat straw, barley, barley straw, hay, rice straw, switchgrass, waste paper, sugarcane bagasse, Sorghum, soy, components obtained from milling of grains, trees, branches, roots, leaves, wood chips, sawdust, shrubs and bushes, vegetables, fruits, flowers, and/or animal manure.    ADVANTAGE - The single, combined chemical and enzymatic hydrolysis method for converting polysaccharides to monosaccharides: utilizes fewer enzymes to obtain high saccharification yield for each milligram of the enzyme used; increases the enzyme efficiency; reduces the cost of the hydrolysis step; and yields fermentable sugars in high concentration while avoiding the formation of detrimental impurities.    DETAILED DESCRIPTION - Producing a concentrated sugar solution from a biomass, comprises: (a) delignifying the biomass by (i) contacting the biomass, comprising lignin and having a glucan/xylan weight ratio of G1/X1, with water and at least one nucleophilic base to form a biomass slurry having a pH of 12.5-13, and (ii) maintaining the biomass slurry under reaction conditions such that the slurry attains a pH of 9.5-10 and has a glucan/xylan weight ratio of G2/X2 within 15% of the value of G1/X1, where the slurry comprises a lignin-containing liquid fraction and a solid fraction comprising a polysaccharide enriched biomass, G1 and G2 are grams of glucan per 100 grams of biomass and biomass slurry, respectively, and X1 and X2 are grams of xylan per 100 grams of biomass and biomass slurry, respectively; (b) contacting the solid fraction of the polysaccharide enriched biomass with an aqueous acid solution comprising at least one mineral acid at reaction conditions sufficient to produce an intermediate saccharification product comprising xylose, xylan and glucan, where the concentration of the solid fraction in the aqueous acid solution is 13-20 wt.%; and (c) contacting the intermediate saccharification product with a saccharification enzyme consortium at a pH of 4.5-5.5 at reaction conditions sufficient to produce a final saccharification product comprising at least 7 wt.% of fermentable sugars, based on the total weight of the saccharification product, in 24 hours of contact with the saccharification enzyme consortium.