Thermophilic methane production from cattle waste
Methane production from waste of cattle fed a finishing diet was investigated, using four 3-liter-working volume anaerobic digestors at 60/sup 0/C. At 55/sup 0/C a start-up culture, in which waste was the only source of bacteria, was generated within 8 days and readily adapted to 60/sup 0/C, where efficiency of methanogenesis was greater. Increasing the temperature from 60 to 65/sup 0/C tended to drastically lower efficiency. When feed concentrations of volatile solids (VS, organic matter) were increased in steps of 2% after holding for 1 month at a given concentration, the maximum concentrations for efficient fermentation were 8.2, 10.0, 11.6, and 11.6% for the retention times (RT) of 3, 6, 9, and 12 days, respectively. The VS destructions for these and lower feed concentrations were 31 to 37, 36 to 40, 47 to 49, and 51 to 53% for the 3-, 6-, 9-, and 12-day RT digestors, respectively, and the corresponding methane production rates were about 0.16, 0.18, 0.20, and 0.22 liters/day per g of VS in the feed. Gas contained 52 to 57% methane. At the above RT and feed concentrations, alkalinity rose to 5000 to 7700 mg of CaCO/sub 3/ per liter (pH to 7.5 to 7.8), NH/sub 3/ plus NH/sub 4//sup +/ to 64 to 90 mM, and total volatile acids to 850 to 2050 mg/liter as acetate. The 3-day RT digestor was quite stable up to 8.2% feed VS and at this feed concentration produced methane at the very high rate of 4.5 liters/day per liter of digestor. Increasing the percentage of feed VS beyond those values indicated above resulted in greatly decreased organic matter destruction and methane production, variable decrease in pH, and increased alkalinity, ammonia, and total volatile acid concentrations, with propionate being the first to accumulate in large amounts. These studies indicate that loading rates can be much higher than those previously thought useful for maximizing methanogenesis from cattle waste. 7 figures, 6 tables.
- Research Organization:
- Univ. of Illinois, Urbana
- OSTI ID:
- 6461087
- Journal Information:
- Appl. Environ. Microbiol.; (United States), Journal Name: Appl. Environ. Microbiol.; (United States) Vol. 33:2; ISSN AEMID
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
090122* -- Hydrocarbon Fuels-- Preparation from Wastes or Biomass-- (1976-1989)
140504 -- Solar Energy Conversion-- Biomass Production & Conversion-- (-1989)
AGRICULTURAL WASTES
ALKANES
ANAEROBIC DIGESTION
BIOCONVERSION
BIOSYNTHESIS
DIGESTION
HYDROCARBONS
MANAGEMENT
MANURES
METHANE
ORGANIC COMPOUNDS
ORGANIC WASTES
PROCESSING
SYNTHESIS
THERMOPHILIC CONDITIONS
WASTE MANAGEMENT
WASTE PROCESSING
WASTES