Enhancement of alkaline-oxidative delignification of wheat straw by semi-batch operation in a stirred tank reactor.

This paper compares a semi-batch operation and a conventional one of an alkaline oxidative pretreatment of wheat straw carried out in a stirred tank reactor. For the pretreatment, different concentrations of biomass (6% up to 12% w/v) and two different particle sizes (mesh #40-60 and #>60) were experimented. The performance of processes was evaluated through the analysis of lignocellulosic composition of the biomass, and the enzymatic hydrolysis of pretreated biomass using the Cellic® CTec2 enzyme complex by Novozymes®. The process time of semi-batch operation is significantly lower than the batch one and enables a higher load of biomass, showing a delignification yield between 55 and 60%. In the first 5 h of reaction time, the enzymatic hydrolysis experiments reached their maximum yields of 72 and 66% according to reducing sugars conversion when using the mesh #>60 mesh and #40-60, respectively.