Intensification of enzymatic saccharification at high solid loading of pretreated agave bagasse at bioreactor scale

Abstract

Enzymatic saccharification of pretreated lignocellulosic biomass is a key step in the biochemical biorefineries. To be economically practical for large-scale use, the process must be run at high solids loadings, notably biomass concentrations of more than 15 % (w/v). However, as the solids loading increases, biomass develops a high-viscosity slurry that is severely mass transfer constrained and more difficult to mix, which restricts the addition of even more solids. Using a commercial enzyme mixture of cellulases and hemicellulases, high solid loading hydrolysis of hydrothermally and CO2-H2O pretreated agave bagasse was carried out in a continuous stirred tank bioreactor (CSTBR) and horizontal bioreactor (HB) to generate high glucose concentrations. With complete saccharification of 100 %, operation at the CSTBR at 20 % (w/v) solid loading yielded 119.9 g/L of glucose concentration, while operating at the HB at the same level of substrate loading was able to produce 134.4 g/L of glucose concentration. CO2-H2O pretreated biomass produced 123.6 g/L of glucose at the same loading on operation with a HB. The hydrolysis was greatly enhanced by the enzyme mixture. The current glucose conversion outcomes of hydrothermally processed biomass were unquestionably greater, with an energy efficiency 2.291 gsugar/MJ. The results of the present study conclusively show the concentration of glucose working at high solid loading by analyzing the energy consumption to improve the mechanical phenomenon at the stage of pretreatment hydrolysis. For the development of biorefineries, the design and development of this process will enable the establishment of ideal operating conditions and energy efficiency.