Delignification of biomass with sequential base treatment

A method for the production of a saccharification product, the method comprising:

• a) providing a cellulosic feedstock comprising lignin;
• b) contacting, in water, the feedstock of (a) with at least one metal carbonate at a time of 0 hour at a temperature of no more than 200° C. to produce a first delignification slurry;
• c) contacting the first delignification slurry with a nucleophilic base at a concentration of no more than 8% on a mass basis at a time of at least 0+0.5 hour and at a temperature of no more than 200° C. to form a second delignification slurry comprising a lignin-containing liquid fraction and a polysaccharide-enriched solid fraction;
• d) separating the lignin-containing liquid fraction from the polysaccharide-enriched solid fraction;
• and
• e) contacting at least a portion of the polysaccharide-enriched solid fraction with an enzyme consortium to produce a saccharification product comprising xylose and glucose monomers wherein the overall yield of xylose and glucose monomers in the saccharification product are individually at least about 50%;
• wherein said enzyme consortium consists essentially of cellulases and xylanases and wherein saccharification occurs under the conditions of a pH of about 4.5 to about 5.7 and a temperature of about 45° C. to about 55° C.