Robust enzymatic saccharification of a Douglas-fir forest harvest residue by SPORL

Forest harvest residues can be a cost-effective feedstock for a biorefinery, but the high lignin content of forest residues is a major barrier for enzymatic sugar production. Sulfite pretreatment to overcome strong recalcitrance of lignocelluloses (SPORL) was applied to a Douglas-fir (Pseudotsuga menziesii (Mirb) Franco var. menziesii) forest residue in a range of sulfite and acid loadings at 165°C for 75 min with liquid to wood ratio of 3:1. Sodium bisulfite and sulfuric acid charge as mass fraction of oven dry biomass of 12% and 2.21%, respectively, was optimal in terms of enzymatic cellulose saccharification, sugar yield and formation of hydroxymethylfurfural (HMF) and furfural. Enzymatic glucose yield was 345 g kg⁻¹, or equivalent to 82.3% of theoretical at a cellulase (CTec2) dosage of 15 filter paper unit (FPU) per gram of glucan. HMF and furfural formation were low at approximately 2.5 g L⁻¹ each in the pretreatment hydrolyzate. Delignification was important to achieve good cellulose saccharification efficiency, however, approximately 80-90% hemicellulose removal is also required. Substrate enzymatic digestibility (SED) was found to correlate to a combined parameter Z(CHF) of delignification and hemicellulose dissolution well, suggesting that the combined hydrolysis factor (CHF) - a pretreatment severity measure - can be used to predict saccharification of forest residue for scale-up studies to reduce numbers of experiments.Keywords: Forest harvest residue, Pretreatment, Biofuel, Enzymatic hydrolysis/saccharification, Pretreatment severit

Using sulfite chemistry for robust bioconversion of Douglas-fir forest residue to bioethanol at high titer and lignosulfonate: A pilot-scale evaluation

This study demonstrated at the pilot-scale (50 kg) use of Douglas-fir forest harvest residue, an underutilized forest biomass, for the production of high titer and high yield bioethanol using sulfite chemistry without solid–liquor separation and detoxification. Sulfite Pretreatment to Overcome the Recalcitrance of Lignocelluloses (SPORL) was directly applied to the ground forest harvest residue with no further mechanical size reduction, at a low temperature of 145°C and calcium bisulfite or total SO₂ loadings of only 6.5 or 6.6 wt% on oven dry forest residue, respectively. The low temperature pretreatment facilitated high solids fermentation of the un-detoxified pretreated whole slurry. An ethanol yield of 282 L/tonne, equivalent to 70% theoretical, with a titer of 42 g/L was achieved. SPORL solubilized approximately 45% of the wood lignin as directly marketable lignosulfonate with properties equivalent to or better than a commercial lignosulfonate, important to improve the economics of biofuel production.Keywords: High titer biofuel, Lignosulfonate, Pretreatment, Forest residues, Sulfite pulpin

Case studies on sugar production from underutilized woody biomass using sulfite chemistry

We examined two case studies to demonstrate the advantages of sulfite chemistry for pretreating underutilized woody biomass to produce sugars through enzymatic saccharification. In the first case study, we evaluated knot rejects from a magnesium-based sulfite mill for direct enzymatic sugar production. We found that the sulfite mill rejects are an excellent feedstock for sugar production. In the second study, we presented SPORL (sulfite pretreatment to overcome the recalcitrance of lignocelluloses), a sulfite pretreatment process based on modified sulfite pulping for robust bioconversion of softwood forest residues. Sulfite pulping technology is well developed, with proven commercial scalability, and sulfite pretreatment is a strong contender for commercial adoption. Application: Mills can consider sulfite chemistry, which has the advantage of high-yield sugar production from woody biomass through enzymatic saccharification.This is the publisher’s final pdf. The published article is copyrighted by Tappi Press and can be found at: http://www.tappi.org/tappijourna

Characterization of forest residuals for bio-jet fuel production

Softwood feedstock samples collected throughout the Pacific Northwest have been characterized for carbohydrate, lignin, and extractives content. Some of the samples have received exhausting testing through pretreatment, hydrolysis and fermentation into alcohols. In addition, the cost impacts associated with various feedstock processing options have been quantified in order to evaluate the economic impacts to deliver a “standard sized” feedstock product for conversion into bio-jet fuel and co-products. Video available at https://www.youtube.com/watch?v=gcDjDaafxlg

Process Design and Economics for Biochemical Conversion of Softwood Lignocellulosic Biomass to Isoparaffinic Kerosene and Lignin Co-products

This techno-economic analysis has been prepared for a greenfield integrated biorefinery to produce renewable jet fuel and co-products from softwood forest harvest residuals

Feedstock Sourcing: NARA Years 4-5

The report characterizes the varied forest residual feedstock samples assessed during the NARA project and explores economic sensitivity to key characteristics (size, moisture, chemical composition)

Economic implications of grinding, transporting and pretreating fresh versus aged forest residues for biofuel production

The moisture content in forest harvest residues is a key factor affecting the supply cost for bioenergy production. Fresh harvest residues tend to contain higher amounts of water thus making transportation inefficient. Additionally, fresh harvest residues contain greater amounts of needles and bark that may reduce the content of polysaccharides, thus, affecting the production of liquid fuels derived from cellulosic components. In this study, we estimated the downstream economic effect in the supply chain of collecting, grinding, transporting and pretreating fresh versus aged residues. Specifically, we analyzed the effect of feedstock moisture content on grinder fuel consumption, bulk density, needles and bark content and polysaccharides proportion. Fresh forest harvest residues were 60% moisture content (wet basis) and aged forest residues were 15% moisture content. The bark and needles proportion is 6.1% higher in fresh versus aged residue. Polysaccharides were 26% higher in aged residue as compared to fresh residue. On a dry tonne basis, the cost of grinding fresh residues was about the same as aged residues. However, considering the difference in bulk density on transportation cost and the difference in polysaccharides yield, the value gain for in-field drying range from USD 29.6 to 74.9 per oven-dry tonne.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Feedstock Sourcing: NARA Years 1-3

This report was completed by Weyerhaeuser staff and evaluates the cost and quality of softwood forest residual feedstock in the Pacific Northwest used to produce bio-jet fuel and co-products

Feedstock Logistics

This report is a series of five reports that cover the varied challenges and opportunities related to processing and transporting forest biomass to a biorefinery. Topics covered in this collection include 1) biomass recovery coefficients for OR, WA, ID, MT; 2) moisture management strategies and models; 3) collection and transport models for regional modeling; 4) chipping and grinding production to meet alternative feedstock specifications; and 5) new trailer designs to improve transport efficiency

Production of 1,000 Gallons of Biojet in the NARA Consortium

This report describes the steps and conditions used to produce 1,000 gallons of biojet fuel made from forest residuals