Optimisation study of Ulmus pumila woody biomass fractionation by steam explosion for bioproducts production

Abstract

Ulmus pumila represents a promising lignocellulosic biomass source for biofuels and bioproducts production since it can grow in low rainfall and extreme temperature zones. A first step in the conversion process is biomass fractionation to enhance the performance of the hydrolysis and subsequent biological conversion steps. The aim of this work is to optimise the main variables (temperature, residence time and the addition or not of sulphuric acid) of steam explosion to pretreat Ulmus pumila biomass. The optimal conditions to maximise both glucose and xylose recovery were 204.8 °C and 30 mg H₂SO₄/g biomass, obtained through a multilevel factorial design of experiments. Additionally, enzymatic hydrolysis using high solid loads (15% and 20% (w/w)) and different enzyme doses was studied. As a result, steam explosion at optimal conditions followed by enzymatic hydrolysis with 20% solid loading and 60 mg protein/g cellulose of enzyme allow the recovery of 70% of the potential sugars.