Dilute acid pretreatment of biomass at high solids concentrations

The dilute acid pretreatment of biomass (aspen wood and wheat straw) at high solids concentrations (up to 40 weight percent) has been investigated. It produces a concentrated monomeric soluble sugar stream (mainly xylose) with little degradation of the available sugars and a solid residue containing cellulose and lignin. The cellulose remaining in the residue from both aspen and straw pretreated at either 140 degrees or 160 degrees was highly digestible with commercial available enzymes. A somewhat higher acid consumption for wheat straw compared with that for aspen can be alleviated by a cation-removal step.