Biological Conversion of Biomass to Methane Corn Stover Studies. Project Report, December 1, 1977-August 1, 1978

摘要

A series of experiments was conducted to determine the performance characteristics of the methane fermentation process using corn stover obtained from the University of Illinois farms and processed through four parallel fermenters each having a capacity of 775 liters. A continuous feed system was employed to determine the conversion efficiency. The dewatering characteristics of the effluents and the quality of the liquid and solid residues were determined. The biodegradability of corn stover is low. Data obtained at a fermentation temperature of 59 +-1 exp 0 C show that only 36 percent of the volatile solids are biodegradable. The first order rate constant for this conversion was found to be 0.25 day exp -1 . Pretreatment with caustic (NaOH) concentration of 0.30 molar (5 g/100 g dry stover) and a temperature of 115 exp 0 C for one hour increased the biodegradable fraction to 71 percent of the volatile solids. The reactor slurries were easily dewatered by both vacuum filtration and centrifugation. Corn stover does not appear to be attractive economically at the present energy prices. At a chemical cost of $154/tonne ($140/ton), the NaOH pretreatment adds approximately $5.2/tonne to the cost of processing the stover. At a methane yield of 0.25 m exp 3 /kg of solids fed, this adds a total cost of $2/100 m exp 3 ($0.57/MCF) for this process alone. Addition of stover acquisition costs ($20/dry tonne of stover), total processing costs without gas cleanup ($21/tonne) and residue disposal ($3/tonne of wet cake), the cost of fuel gas would be in the neighborhood of $9.76/GJ ($10.30/10 exp 6 Btu).This cost excludes all profit, taxes, etc. associated with private financing. Depending upon financing methods, tax incentives, etc., it may be necessary to add up to an additional $2.00/GJ to the cost of this fuel gas. (ERA citation 05:011411)