Discharging pretreated biomass from a pretreatment reactor and mixing the discharged pretreated biomass with a cooling liquid in a vessel provides a cooled slurry having a consistency that is less than about 12 wt %. Since the consistency is relatively low, the cooled slurry may be pumped to a higher elevation using standard pumping equipment. At the higher elevation, the cooled slurry may be separated into a first stream comprising a liquid component of the slurry and a second other stream comprising a solid component of the slurry (e.g., having a consistency between about 15 wt % and 40 about wt %). The solid component may be fed to an inlet of a hydrolysis reactor, while the liquid component may be fed to a cooling system that provides a cooled stream. The cooled stream may then be cycled back to the vessel.