Sulfite Post-Treatment To Simultaneously Detoxify and Improve the Enzymatic Hydrolysis and Fermentation of a Steam-Pretreated Softwood Lodgepole Pine Whole Slurry

Previous work has shown that sulfonation post-treatment employed at a temperature of 130–140 °C modifies the lignin in steam-pretreated softwood to improve the ease of hydrolysis of the resulting “post-treated” substrate. Sulfite has also been shown to detoxify water-soluble fractions originating from the steam pretreatment of softwood to enhance fermentation. Consequently, lignin modification and detoxification could be combined in a single process step to simultaneously improve the ease of hydrolysis and fermentability of a high solids (25% w/v) substrate which contains the combined 5% (w/v) water-soluble and 20% (w/v) water-insoluble fractions (“high solids whole slurry”), originating from the steam pretreatment of softwood biomass. Unlike previous work on sulfite post-treatment applied to the water-insoluble fractions of steam-pretreated softwood, the sulfite treatment of the steam-pretreated softwood high solids whole slurry was effective when performed at a reduced temperature (70 °C) when sodium ca...