State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China.
Bioresour Technol. 2010 Apr;101(8):2782-92. doi: 10.1016/j.biortech.2009.10.076. Epub 2009 Dec 16.
This study investigated the effects of chemical pretreatment and disk-milling conditions on energy consumption for size-reduction and the efficiency of enzymatic cellulose saccharification of a softwood. Lodgepole pine wood chips produced from thinnings of a 100-year-old unmanaged forest were pretreated by hot-water, dilute-acid, and two SPORL processes (Sulfite Pretreatment to Overcome Recalcitrance of Lignocellulose) at acid charge on oven dry (od) wood of 0% and 2.21%. The pretreated wood chips were then milled using a laboratory disk mill under various solids-loadings and disk-plate gaps to produce substrates for enzymatic hydrolysis. We found that post-chemical-pretreatment size-reduction of forest biomass can decrease size-reduction energy consumption by 20-80% depending on the pretreatment applied under 20% solids-loading and a disk-plate gap of 0.76 mm in milling. SPORL with a sodium bisulfite charge of 8% and sulfuric acid charge of 2.21% on wood was the most effective in decreasing size-reduction energy consumption. Solids-loading had the most significant effect on disk-milling energy. When solids-loading was reduced from 30% to 3%, disk-milling energy could be decreased by more than a factor of 10 for wood chips pretreated by both SPORL and dilute-acid at an acid charge of 2.21%. The enzymatic hydrolysis glucose yields (EHGY) from the substrates produced by all pretreatments were independent of the solids-loading in milling, indicating that these energy savings in size-reduction can be realized without affecting EHGY. When wood chips were pretreated by SPORL with 2.21% acid charge, size-reduction energy consumption was decreased to less than 50 Wh/kg od wood at a practical solids-loading of approximately 10-20%, equivalent to that used in size-reduction of agriculture biomass, with excellent EHGY of about 370 g per kg od wood. Similar effects on size-reduction energy savings and excellent EHGY were also achieved when large disk-plate gaps (up to 1.52 mm studied) were applied in disk-milling of wood chips pretreated by SPORL with acid.
本研究考察了化学预处理和盘式磨浆条件对尺寸减小的能耗以及软木纤维素酶糖化效率的影响。从百年未管理森林采伐的小径材中生产的花旗松木屑用热水、稀酸和两种 SPORL 工艺（亚硫酸盐预处理克服木质纤维素的顽固性）在酸负荷为 0%和 2.21%时对 oven dry (od) 木材进行预处理。然后，使用实验室盘式磨浆机在不同的固体负荷和盘板间隙下将预处理后的木屑磨碎，以制备用于酶水解的基质。我们发现，根据应用的预处理方法，在 20%的固体负荷和 0.76mm 的盘板间隙下进行的化学后预处理可以降低 20-80%的生物质尺寸减小能耗。用 8%亚硫酸钠和 2.21%硫酸对木材进行的 SPORL 预处理在降低尺寸减小能耗方面最为有效。固体负荷对盘式磨浆能耗的影响最大。当固体负荷从 30%降低到 3%时，用 SPORL 和稀酸预处理的木屑在 2.21%的酸负荷下，盘式磨浆能耗可降低 10 倍以上。所有预处理方法制备的基质的酶水解葡萄糖产率（EHGY）与磨浆中的固体负荷无关，表明在不影响 EHGY 的情况下，可以实现尺寸减小方面的这些节能。当用 2.21%酸负荷的 SPORL 预处理木屑时，在约 10-20%的实际固体负荷下，尺寸减小能耗可降低至 50Wh/kg od 木材以下，相当于农业生物质尺寸减小的能耗，同时具有约 370g/kg od 木材的优异 EHGY。在 SPORL 预处理的木屑的盘式磨浆中应用较大的盘板间隙（研究中最大可达 1.52mm）时，也可以获得类似的尺寸减小节能效果和优异的 EHGY。
