Fate of sulfate during the thermophilic methane fermentation process

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6914754

McFarland, M J

The reactor design utilized was the suspended growth thermophilic anaerobic contact system. The experimental program was divided into four separate investigations which included sulfate interaction in continuously fed contact reactors, sulfide-pH speciation effects, metal control of sulfide precipitation, and maximum kinetic measurements. During continuous fermenter operation, negligible effluent sulfate levels indicated that complete reduction of sulfate occurred with influent loadings up to 80 mg/l-d SO/sub 4//sup -2/-S. Comparison of the maximum sulfate reduction rate obtained during batch digestion to the maximum specific sulfate loading rate during continuous flow operation illustrated that sulfate reduction kinetics were nonlimiting, and thus, responsible for complete removal of sulfate. By proper pH maintenance, stable reactor conditions were obtained during the entire range of influent sulfate concentrations tested. However, as the influent SO/sub 4//sup -2/-S/COD ratio was increased from 0.003 to 0.08, the methane production rate decreased by 60% (from 0.26 to 0.11 l CH/sub 4//L-day), and volatile acid concentrations increased from 200 to 4500 mg/l acetate. Significant inhibition of thermophilic methanogenesis appeared at a soluble sulfide concentration greater than 120 mg/l sulfide-sulfur. Sulfide speciation was sensitive to variations in fermenter pH. Insoluble iron phosphate additions were an efficient gaseous sulfide control process with no adverse effects on methane production.

• Research Organization: Cornell Univ., Ithaca, NY (USA)
• OSTI ID: 6914754
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
090122* -- Hydrocarbon Fuels-- Preparation from Wastes or Biomass-- (1976-1989)
140504 -- Solar Energy Conversion-- Biomass Production & Conversion-- (-1989)
ADDITIVES
ALKANES
ANAEROBIC DIGESTION
BIOCONVERSION
BIOREACTORS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CONTROL
DIGESTION
GAS YIELDS
HYDROCARBONS
IRON COMPOUNDS
IRON PHOSPHATES
KINETICS
LOADING RATE
MANAGEMENT
METHANE
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PH VALUE
PHOSPHATES
PHOSPHORUS COMPOUNDS
PROCESSING
REACTION KINETICS
SULFATES
SULFIDES
SULFUR COMPOUNDS
SYNTHESIS
THERMOPHILIC CONDITIONS
TRANSITION ELEMENT COMPOUNDS
WASTE MANAGEMENT
WASTE PROCESSING
YIELDS