General Method to Correct the Fluctuation of Acid Based Pretreatment Efficiency of Lignocellulose for Highly Efficient Bioconversion

Acid based pretreatment efficiency frequently changes with the varying properties of raw lignocellulose feedstock and creates disturbances in industrial biorefining applications. This study revealed that high alkaline ash content in feedstocks neutralized partial acid catalyst and consequently reduced the pretreatment efficiency. The ash content varies in each batch of feedstocks by differences in growing regions, seasons, irrigation, soil, fertilizer use, harvest operation, transportation, storage, and prehandling operations. These differences lead to frequent and significant fluctuations of acid based pretreatment efficiency. The practical solution to the fluctuation should be simple and fast, preferably without performing a time-consuming pretreatment operation assay. Here we proposed a Base pH Approaching method to correct the fluctuating pretreatment efficiency by a simple titration procedure. The method contained only two simple steps in flasks. The first step is the measurement of the inherent base pH value of the thoroughly washed feedstock slurry, and the second step is the adjustment of sulfuric acid usage by titration of the feedstock slurry to the base pH value. The method is universally effective to different feedstocks (corn stover, wheat straw, or rice straw) using different strains (yeasts or bacteria) for different products (ethanol and lactic acid) and different fermentation types (SSF or SSCF).