Method and apparatus for conversion of cellulosic material to ethanol

A method of continuous hydrothermal pretreatment of lignocellulosic biomass feedstock having an amount of lignin comprising:

• (i). soaking of the lignocellulosic material having said amount of lignin, followed by
• (ii). continuous pressurized hydrothermal pretreatment within a pressurized pretreatment reactor at temperatures between 170 and 200° C.,
• wherein the feedstock is cereal straw, corn stover or bagasse,
• wherein hydrothermal pretreatment is conducted without addition of acids, bases or other chemicals,
• wherein, following soaking and pretreatment, the pretreated feedstock is subsequently subject to at least one pressing operation while it is still under pressure or after it has been unloaded from the pretreatment reactor to create a fibre fraction and a liquid fraction, and
• wherein temperature and residence time for hydrothermal pretreatment within the pretreatment reactor are selected at lower severity than that required for pretreatments that seek maximal removal of hemicellulose from the fibre fraction such that greater than 80% of the said lignin remains in the fibre fraction following the at least one pressing operation,
• further characterized in that the fibre fraction having greater than 80% of said lignin amount following the at least one pressing operation is subsequently subject to enzymatic saccharification.