Fertilizers
Why implement fertilizers in hydrocarbon bioremediation techniques?
In anaerobic environments, microorganisms lack oxygen and therefore need other electron acceptors in order to utilize hydrocarbons as an energy source via oxidation-reduction reactions. Nitrate, ferric iron, or sulfate, when added in the form of fertilizer, can contribute to the successful remediation of contaminated regions.
How do fertilizers help degrade hydrocarbons in contaminated soil?
Bacteria that are usually found in the subsurface and in contaminated aquifers can use nitrate, sulfate or ferric iron as an electron acceptor. Providing low levels of oxygen in addition to the other electron acceptors for the bacteria results in oxidation of hydrocarbon contamination and allows for intermediates of this oxidation to degrade via anaerobic processes.
Of the electron acceptors other than oxygen, nitrate is preferable because it is water soluble, does not precipitate oxides, is inexpensive, and is non-toxic to aquifer microorganisms. Still, nitrate use is restricted by drinking water standards.
Anaerobic bacteria capable of growing under both anaerobic and aerobic conditions (like denitrifiers) are more efficient bioremedial agents.
For more information on fertilizers in bioremediation strategies, see Halogenated Organic Solvents and Halogenated Organic Compounds.
The Nitrogen Fixers
Range of N fixing organisms:
FACULTATIVE (aerobic when not fixing N) |
Klebsiella |
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Bacillus |
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Enterobacter |
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Citrobacter |
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Escherichia |
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Proprionibacterium |
FACULTATIVE PHOTOTROPHS |
Rhodospirillum |
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Rhodopseudomonas |
MICROAEROPHILES( normal aerobes when not fixing N) |
Mycobacterium |
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Thiobacillus |
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Spirillum |
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Aquaspirillum |
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Methanosinus |
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Enterobacter: Rhodospirillum: Mycobacterium:
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SOURCES: Meckenstock