Biological conversion of biomass to methane. Final report, January 1, 1980-March 31, 1981

Technical Report · Wed Jul 01 04:00:00 EDT 1981

DOI:https://doi.org/10.2172/6257750· OSTI ID:6257750

McFarlane, P. N.; Pfeffer, J. T.

The production of a fuel gas by the anaerobic digestion of crop residues is economically unattractive because of the poor conversion efficiencies experienced with high rate methane fermentation processes. Pretreatment of the residue prior to fermentation has been found to substantially improve the biodegradability of the ligno-cellulose fibers. Thermo-chemical pretreatment using NaOH at temperatures up to 200/sup 0/C has been found to be effective for laboratory-scale studies. The effectiveness of this pretreatment was evaluated using 0.775-m/sup 3/ methane fermentation reactors. A minimum feed slurry solids concentration of five percent was used. Pretreatment conditions tested included NaOH concentrations ranging from 1.33 to 13.3% by weight, treatment temperature ranging from 106 to 160/sup 0/C, solids concentration during pretreatment ranging from 16.8 to 33.2% and pretreatment time ranging from 0.316 to 3.16 hours The solids concentration and pretreatment temperature did not have a significant effect on the gas yield from corn stover. Increases in caustic dosage and pretreatment time increased the gas yield until inhibitory conditions developed. Caustic levels above 7.33% and pretreatment times greater than 120 minutes produced products that caused severe inhibition of the methanogenic bacteria when processing corn stover. When processing wheat straw, all pretreatment conditions resulted in inhibition of the methaogenic microorganisms. The first-order rate constant based on COD reduction for corn stover was increased from 0.25 day/sup -1/ for untreated stover to 0.51 day/sup -1/ for pretreatment conditions of 4.33% caustic and a one-hour pretreatment time. The stover biodegradability was increased from 36% to 78%. Because of the high cost of caustic, the improved conversion efficiencies will not be cost-effective. High rate methane fermentation of corn stover and wheat straw does not appear to be economically feasible.

• Research Organization: Solar Energy Research Inst., Golden, CO (USA); Illinois Univ., Urbana (USA). Dept. of Civil Engineering
• DOE Contract Number: AC02-77CH00178
• OSTI ID: 6257750
• Report Number(s): SERI/TR-98357-1; ON: DE82003928
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
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550700 -- Microbiology
59 BASIC BIOLOGICAL SCIENCES
AGRICULTURAL WASTES
ALKALINE HYDROLYSIS
ALKANES
ANAEROBIC DIGESTION
BACTERIA
BIOCONVERSION
CEREALS
CHEMICAL REACTIONS
DATA
DECOMPOSITION
DIGESTION
EXPERIMENTAL DATA
FEASIBILITY STUDIES
GRAMINEAE
GRASS
HYDROCARBONS
HYDROLYSIS
INFORMATION
INHIBITION
LYSIS
MAIZE
MANAGEMENT
METHANE
METHANOGENIC BACTERIA
MICROORGANISMS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC WASTES
PLANTS
PROCESSING
PRODUCTION
SOLVOLYSIS
STRAW
TEMPERATURE DEPENDENCE
WASTE MANAGEMENT
WASTE PROCESSING
WASTES
WHEAT