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SYSTEM DESCRIPTION
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Full
Description |
The following is an excerpt from our System Description.
(PDF of FULL description available above.)
3.1 Microbial Degradation of Hydrocarbons
Microbial degradation of hydrocarbons is well documented in numerous
publications and scientific literature. There are several commercially available
processes where procaryotic organisms consume organic material under certain
conditions to reduce them to carbon dioxide, water and biomass. By a substantial
margin, bio-stimulation and augmentation are the fastest acting, most complete
method for remediation of hydrocarbons and volatile organic compounds.
Discussion here will be limited to this method.
Bio-stimulation (enhancement) involves adding specific nutrients for the
indigenous bacteria in an oxygen rich environment, and bio-augmentation is
addition of bacteria selected for affinity to the specific contaminates. These
methods have proven to be valid under certain site conditions and have been
utilized for the effective and successful cleanup of contaminated soil and
water.
Bacteria, as all living organisms, have certain chemical and physical growth
requirements. The proper application of these conditions is especially important
in considering bioremediation.
3.2 Basic
Mechanisms
An energy source is needed for biosynthetic reactions to make polymers such as
proteins fromamino acids and RNA and DNA from nucleotides.
Some Bacteria can utilize light energy, however the ones that we are concerned
with oxidize chemical compounds to obtain their energy. The bacteria that are
involved in bioremediation are chemoorganotrophs as they utilize organic
compounds for their energy source.
A carbon source is required for all of the polymeric units in the cell such as
DNA, RNA, and proteins. Some bacteria can utilize carbon dioxide as a sole
carbon source ,however, the organisms concerned with bioremediation are
heterotrophs as they require an organic source of carbon.
A nitrogen source such as ammonia, nitrite, nitrate, and organic nitrogen is
required. Nitrogen is a component in the amino acids of proteins and in the
purines and pyrimidines of RNA and DNA. Phosphate is a component part of the
nucleotides composing RNA and DNA these are required for energy transfer
reactions.
Minerals such as magnesium, manganese, iron, etc., are required and are
typically readily available in the soil. No additional augmentation is required.
Oxygen Supply
Utilization of aliphatic hydrocarbons by microorganisms is strictly an aerobic
process. The initial oxidation step of aliphatic hydrocarbons involves molecular
oxygen as a reactant and one of the oxygen molecules is actually incorporated
into the oxidized product. The aromatic group of
hydrocarbons can be viewed as derivatives of benzene. The breakdown of aromatic
hydrocarbons involves the action of either oxygenases or mixed function
oxygenases. These two reaction sequences both form catechol which can be
degraded in a number of ways leading to either acetyl CoA or TCA cycle
intermediates. Very importantly, the oxygen concentration is the rate limiting
factor in the biodegradation of petroleum based products. Approximately, four
pounds of oxygen is required for the biological oxidation of one pound of
hydrocarbon. Microbial activity during bioremediation is often frequently
limited by insufficient oxygen due to slow rates of diffusion into the interior
of the soil layers or piles and into the center of soil aggregates. Excess water
has been shown to severely limit the oxygen concentration and result in
anaerobic conditions. Effective application can result in greatly accelerated
cleanups as generally, the greater the mass of oxygen that can be distributed
the more rapid and complete the cleanup.
(Click here to download FULL Bioremediation System Description in PDF format.)
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In-Situ Oxygen Enriched Remediation
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(Methyl Tertiary Butyl Ether)
Mineralization in Surface-Water Sediment |
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In-situ Bioremediation is a technique for
removing biodegradable contaminates from groundwater
(EPA-510-F-93-018) that relies on microbes and supplemental
oxygen to breakdown organic compounds into non-toxic
components.
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Oxygen
enriched soil and groundwater remediation:
• Is the safest, most effective and economical
biochemical transport method
• Operates without toxic chemicals or ozone
• Minimizes formation oxides of nitrogen
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• Is up to
16 times as effective as anaerobic digesters
• Effective on proteins, carbohydrates, fats, oils,
petrochemicals, solvents, pharmaceutical, small and
large molecules, solids and liquids
• Reduces oxygen sag and BOD in receiving streams |
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