TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Method: The method involves contacting the liquified digest slurry with a cellulolytic enzyme to hydrolyze amounts of the cellulose to form glucose, and fermenting the glucose to form ethanol. The method involves contacting liquefied digest slurry with a cellulolytic enzyme, fermenting the xylose, and the fermenting the glucose in a single vessel. The hydrolytic liquefaction is performed in the presence of at least one dicarboxylic acid, and where the pumping is sufficient to cause flow of the slurry through the passage at a linear velocity of at least 1 foot per second. The method involves after the cooling and before the contacting, flashing liquid from the digest slurry to vapors and condensing the vapors upon for heating a second amount of particulate lignocellulosic biomass feedstock. The method involves passing is at a flow rate of at least about 20 gallons per minute. The method involves hydrolyzing the undissolved, biomass particulate from the digest composition with cellulase to convert cellulose in the biomass particulate to glucose. The method involves neutralizing the digest composition with a base. The method involves preparing the digest slurry by contacting a lignocellulosic biomass feedstock with an aqueous solution comprising at least one dicarboxylic acid. Preferred Components: The biomass feedstock is present in a liquid-solid mixture at a solids content of at least 15 wt.% on a dry weight during hydrolytic liquefaction. The liquid of the liquid-solid mixture is at least about 80% water. The velocity of 1 foot per second. The linear velocity of 10-50 feet per second. The digest slurry exhibits a yield stress of 15000 Pascals. The undissolved lignocellulosic biomass particulates comprises at least 10 wt.%, on a dry weight basis, of particles having a maximum dimension of 1 cm or more. The particulate lignocellulosic biomass comprises wood. Preferred Composition: The biomass digest composition exhibits a yield stress of less than half that of the mixture. The digest composition comprises 20 g/l of monomeric xylose. The digest composition comprises 55% of undissolved solids.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The pumping is performed using a centrifugal pump. The heat exchanger is a spiral heat exchanger or plate heat exchanger having a gap width of 1-4 cm. The heat exchanger has a slurry inlet, and a slurry outlet, and where during the pumping a hot aqueous liquid digest slurry, the slurry experiences a pressure drop of 20 psi or more, and during the pumping a hot aqueous liquid digest slurry, the first passage experiences a maximum pressure of 100 psi or more.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The dicarboxylic acid is maleic acid. EXAMPLE - No suitable example given.