Evaluation of mixing systems for biogasification of municipal solid waste

Technical Report · Mon Jun 01 00:00:00 EDT 1981

DOI:https://doi.org/10.2172/6518978· OSTI ID:6518978

Two specially selected mixing systems were tested and evaluated to determine how effectively they could prevent the formation of fibrous mats and stringers during the anaerobic digestion of a slurried mixture of preprocessed municipal solid waste and sewage sludge to produce methane gas. One of the two mixing systems was a mechanical agitator - a vessel-centered rotary shaft with four blades at each of two levels to drive the slurry downward. The second system included three equidistantly placed gas gun assemblies that each produced bubbles at a constant rate to draw the slurry upward. Between August 1977 and September 1978, nine tests were conducted with 3:1 and 9:1 solid waste/sewage ratios and with 4, 7, and 10% total solids in the feedstock. Though the microbial culture was healthy in most tests, the mixing systems were not effective in preventing excessive fibrous mat and stringer formations. These formations occurred because of the high cellulosic content of the feedstock. The test with the best energy recovery had a gas production of 805 liters/kg of volatile solids destroyed. However, the energy recovered was only 50% of the energy available in the solid waste, and only four times greater than the mixing energy expended for that test. The solids accumulations were generally the same for the two mixing systems when they had common test conditions. In all tests, the percent solids for the top level were higher than those for the middle and bottom levels. As the feed ratio and the percent solids in the feedstock were increased, this differential became progressively more pronounced. Moreover, the percent of volatile solids (in a given amount of total solids) for the top level became disproportionately higher than those for the other two levels.

• Research Organization: Systems Technology Corp., Xenia, OH (USA)
• DOE Contract Number: AC05-76CS20100
• OSTI ID: 6518978
• Report Number(s): DOE/CE/20100-1; ON: DE81023781
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
MUNICIPAL WASTES
ANAEROBIC DIGESTION
MIXING
SEWAGE SLUDGE
SOLID WASTES
BIOSYNTHESIS
CHEMICAL REACTORS
COMPARATIVE EVALUATIONS
ENERGY RECOVERY
EQUIPMENT
METHANE
ALKANES
BIOCONVERSION
DIGESTION
HYDROCARBONS
MANAGEMENT
ORGANIC COMPOUNDS
PROCESSING
RECOVERY
SEWAGE
SYNTHESIS
WASTE MANAGEMENT
WASTE PROCESSING
WASTES
090122* - Hydrocarbon Fuels- Preparation from Wastes or Biomass- (1976-1989)