CLEAN SUGAR AND LIGNIN FROM NON-CHEMICALLY PRETREATED LIGNOCELLULOSIC BIOMASS

Methods of producing clean (e.g., low sulfur and metal ion content, and free of fermentation inhibitors) sugar and lignin-rich streams, and downstream conversion products, from lignocellulosic biomass, may include obtaining non-chemically pretreated, milled lignocellulosic biomass, reacting the milled lignocellulosic biomass with an enzymatic agent to produce a slurry that includes converted monomeric lignocellulosic sugars and lignin-rich residuals, and separating the slurry into a sugar stream that includes the converted monomeric lignocellulosic sugars and a lignin-rich stream that includes the lignin-rich residuals. The sugar stream, not including water, includes at least 75% monomeric lignocellulosic sugar, less than 0.20% sulfur, and less than 3.0% metal ion content, and the lignin-rich stream includes at least 35% lignin and less than 0.50% sulfur. Some methods include producing fermentation products such as alcohols and/or organic acids from the sugar stream, and/or use of the lignin residuals in fuels.