Development and testing of a novel lab-scale direct steam-injection apparatus to hydrolyse model and saline crop slurries

作者：Guglielmo Santi; Alessandro D'Annibale; Maurizio Petruccioli; Silvia Crognale; Maurizio Ruzzi; Riccardo Valentini; Mauro Moresi^*

来源：Journal of Biotechnology, 2012, 157(4): 590-597.

DOI：10.1016/j.jbiotec.2011.09.005

• Steam explosion
• Direct steam injection apparatus
• Lignocellulosic material
• Biomass pretreatment
• Saccharification
• Tamarix Jordanis

In this work, a novel laboratory-scale direct steam-injection apparatus (DSIA) was developed to overcome the main drawback of the conventional batch-driven lab rigs, namely the long time needed to heat fiber slurry from room to reaction temperatures greater than 150 degrees C. The novel apparatus mainly consisted of three units: (i) a mechanically-stirred bioreactor where saturated steam at 5-30 bar can be injected; (ii) an automatic on-off valve to flash suddenly the reaction medium after a prefixed reaction time; (iii) a cyclone separator to recover the reacted slurry.
This system was tested using 0.75 dm(3) of an aqueous solution of H2SO4 (0.5%, v/v) enriched with 50 kg m(-3) of either commercial particles of Avicel (R) and Larch xylan or 0.5 mm sieved particles of Tamarix jordanis. Each slurry was heated to about 200 degrees C by injecting steam at 28 bar for 90s. The process efficiency was assessed by comparing the dissolution degree of suspended solid (Y-S), as well as xylose (Y-X), glucose (Y-G), and furfural (Y-F) yields, with those obtained in a conventional steam autoclave at 130 degrees C for 30 or 60 min. Treatment of T. jordanis particles in DSIA resulted in Y-S and Y-G values quite similar to those obtained in the steam autoclave at 130 degrees C for 60 min, but in a less efficient hemicellulose solubilization. A limited occurrence of pentose degradation products was observed in both equipments, suggesting that hydrolysis predominated over degradation reactions. The susceptibility of the residual solid fractions from DSIA treatment to a conventional 120 h long cellulolytic treatment using an enzyme loading of 5.4 FPU g(-1) was markedly higher than that of samples hydrolysed in the steam autoclave, their corresponding glucose yields being equal to 0.94 and 0.22 g per gram of initial cellulose, respectively. Thus, T. jordanis resulted to be a valuable source of sugars for bioethanol production as proved by preliminary tests in the novel lab rig developed here.

• 出版日期2012-2-20