Sulfate reduction, nutrient limitation, and reactor design considerations in anaerobic digesters
Three areas of improvement in anaerobic digestion were investigated: inhibition of sulfate reduction, nutrient limitation, and reactor design. In the anaerobic treatment of wastewaters containing high concentrations of sulfate, hydrogen sulfide, an undesirable end product, is produced by sulfate reducing bacteria (SRB). Research was conducted to evaluate the feasibility of adding SRB-specific biochemical inhibitors to a waste stream as a method of preventing sulfate reduction in continuous anaerobic digesters. Two classes of inhibitory compounds were identified: (1) sulfate analogs and (2) transition metal divalent cations. Molybdate was found to have an immediate inhibitory effect on sulfate reduction, and a delayed effect on other trophic groups. Non-specific inhibition was not caused by a dynamic imbalance due to cessation of fatty acid degradation via sulfate reduction. Transition metals had no effect on sulfate reduction or overall digester performance in high sulfate digesters. The hypothesis that nutrient limitation could be synergistically coupled with the addition of SRB-specific inhibitors was investigated. Recovery of sulfate reduction was slower after molybdate removal from the feed when phosphate was limited as compared with when it was continually added, although this effect may have been an indirect result of non-specific inhibition. Periodic pulse nutrient addition was investigated as a method of (1) reducing cell growth, sludge production and related disposal costs and (2) reducing nutrient addition costs. Sustained waste treatment performance was demonstrated for iron, phosphorus, and nitrogen-free feeds. When withheld nutrients were added in pulses, effective operation could be maintained over long periods. Increasing pulse strength delayed the onset of adverse effects related to nutrient starvation.
- Research Organization:
- Dartmouth Coll., Hanover, NH (United States)
- OSTI ID:
- 5117470
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIOREACTORS
DESIGN
SULFATES
BIODEGRADATION
WASTE WATER
DECONTAMINATION
ANAEROBIC DIGESTION
CARBOXYLIC ACIDS
INHIBITION
MICROORGANISMS
MOLYBDENUM
NUTRIENTS
WATER POLLUTION CONTROL
BIOCONVERSION
CHEMICAL REACTIONS
CLEANING
CONTROL
DECOMPOSITION
DIGESTION
ELEMENTS
HYDROGEN COMPOUNDS
LIQUID WASTES
MANAGEMENT
METALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
POLLUTION CONTROL
PROCESSING
SULFUR COMPOUNDS
TRANSITION ELEMENTS
WASTE MANAGEMENT
WASTE PROCESSING
WASTES
WATER
540320* - Environment
Aquatic- Chemicals Monitoring & Transport- (1990-)
560300 - Chemicals Metabolism & Toxicology