Methane production by anaerobic digestion of Bermuda grass
Bermuda grass (Cynodon dactylon) is one of the high-yield warm-season grasses that has been suggested as a promising raw material for conversion to methane. Experimental work performed with laboratory digesters to study the anaerobic digestion of Coastal Bermuda grass harvested in Louisiana and having a C/N ratio of 24 is described. Methane yields of about 1.9 SCF/lb of volatile solids (VS) added were observed under conventional mesophilic high-rate conditions. When supplemental nitrogen additions were made, the methane yields increased. This observation along with the compositional data compiled on the grass used in this work indicated that the nitrogen content of the unsupplemented grass was insufficient to sustain high-rate digestion at the higher yield level. However, as the C/N ratio was reduced by addition of ammonium chloride, the methane yield continually increased up to 3.5 SCF/lb added at the lowest C/N ratio examined (6.3) even after relatively high concentrations of ammonium nitrogen were measured in the effluent. It appears that the added nutrient had a stimulatory effect on methane production above the point where nitrogen was not limiting. Thermophilic digestion with supplemental nitrogen additions afforded methane yields of about 2.7 SCF/lb VS added. Carbon and energy balances were calculated and the relative biodegradabilities of the organics were estimated. It was concluded from this work that Coastal Bermuda grass can be converted to high-methane gas under conventional anaerobic digestion conditions. The performance of the particular lot of grass studied was substantially improved by supplemental nitrogen additions. (Refs. 12).
- Research Organization:
- Inst. of Gas Technology, 3424 South State St., Chicago, IL 60616
- OSTI ID:
- 5167862
- Journal Information:
- ACS Symp. Ser.; (United States), Vol. 144; Conference: ACS/CSJ Chemical Congress, Honolulu, Hawaii, 2 Apr 1979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GRASS
ANAEROBIC DIGESTION
METHANE
BIOSYNTHESIS
BENCH-SCALE EXPERIMENTS
CARBON
ENERGY BALANCE
NITROGEN
PERFORMANCE
THERMODYNAMICS
YIELDS
ALKANES
BIOCONVERSION
DIGESTION
ELEMENTS
HYDROCARBONS
MANAGEMENT
NONMETALS
ORGANIC COMPOUNDS
PLANTS
PROCESSING
SYNTHESIS
WASTE MANAGEMENT
WASTE PROCESSING
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