A system for treating biomass for the production of ethanol is disclosed. The system comprises an apparatus for unloading bulk material, comprising: a liner positioned against a wall and a floor; wherein the floor comprises an outer edge and an inner edge; wherein the wall comprises an upper edge and a lower edge; wherein the liner comprises an upper edge and a lower edge; wherein the liner can be in a first position or a second position; wherein the bulk material is loaded onto the liner in the first position; and wherein the liner is moved into the second position to facilitate the unloading of the bulk material. The apparatus for unloading bulk materials may comprise one or more cables to move the liner. The apparatus for unloading bulk materials may also comprise a mechanism to retract the one or more cables wherein the mechanism comprises a roller system.