Monday, November 13, 2006

Pretreatment of Lignocellulosic Biomass with Acidic and Enzymatic Additives.

Dirk Philipp1, Kenneth Moore1, Tom Richard2, and Patricia Patrick1. (1) Iowa State Univ, 1301 Agronomy Hall, Ames, IA 50011-1010, (2) The Pennsylvania State Univ, Dept of Ag. and Biological Engineering, 225 Agricultural Engineering Building, University Park, PA 16802-1909

Conversion of lignocellulosic biomass to ethanol may be optimized with novel pretreatment strategies that lessen energy needs for industrial fermentation procedures. We tested the effects of sulfuric acid at 0, 10, and 20 g kg-1 dry matter (DM) and a cellulase/hemicellulase (Multifect A40) at 0, 10, and 100 g kg-1 DM in a factorial arrangement on chemical composition of corn (Zea mays L.) stover following 1, 2, and 4 days of storage. Treatments resulted in a pH reduction to 4.7 after 1 day of storage and further decrease to 4.5 after 4 days. Maximum pH was 5.0 at day 1 when treated with 10 g enzyme kg-1 DM and minimum pH was 3.6 also at day 1 with 20 g H2SO4 kg-1 DM. A treatment of 10 g H2SO4 kg-1 DM and 100 g enzyme kg-1 DM maximized glucose concentration, but recovered quantities were very small (< 17 g kg-1 DM). Xylose maximum concentrations averaged 8.4 g kg-1 DM across 4 days and were achieved with 10 g H2SO4 kg-1 DM and 100 g enzyme kg-1 DM as well. An enzyme treatment alone of 100 g kg-1 DM recovered 7.5 g kg-1 DM. Average concentrations of cellulose (412 g kg-1) did not contrast from untreated stover, but a treatment of 10 g H2SO4 kg-1 DM and 100 g enzyme kg-1 DM resulted in a reduction to 386 g kg-1 DM averaged across all days of storage. Conversely, hemicellulose concentrations averaged 317 g kg-1 DM and differed from those found in the original material (331 g kg-1 DM) but concentrations remained similar during storage. Results suggested that a combination of acidic and enzymatic additives may serve as a valid pretreatment strategy for polysaccharide solubilization in corn stover, but quantities of recovered sugars need to be drastically increased for economic feasibility.