Sufficient premixing enhances enzymatic hydrolysis efficiency of lignocellulose at high-solids loading

Abstract

Low efficiency of the high-solids enzymatic hydrolysis process leads to a sharp increase in energy consumption and enzyme dosage, which hinders the development of lignocellulose biorefinery. Inhomogeneity of trace amounts of enzymes and bulk substrates mixing may be a main barrier to the efficiency. In this study, the mixing degree of enzyme and substrate at high-solids loadings were explored. The 30% solids loading group took 52.9 times longer to reach the same mixing degree as the 5% solids loading group. The mixing process is divided into two stages: reactor-scale mixing and pore-scale mixing, the latter being the rate-limiting step at high-solids loadings. Sufficient premixing improved pore-scale mass transfer, resulting in 194.25% enzymatic hydrolysis efficiency improvement at the enzyme dosage of 5 FPU/g dry matter, cellulase dosage decreased from 40 FPU/g dry matter to 5 FPU/g dry matter and earlier liquefaction at 20% solids loading. Periodic vibration as an efficient premixing method enhanced high-solids enzymatic hydrolysis efficiency. This study is a step forward to the industrial application of high-solids enzymatic hydrolysis.