Some Frequently Asked Questions about Bioremediation

How does PETRO-CLEAR for hydrocarbons and bioaugmentation differ from natural weathering?
In a natural weathering process of hydrocarbons there is an "unzipping" of the long hydrocarbon chain into its next compound. This gradual process continues until the last part of the chain has been reduced to insoluble tailings (PAH).
In bioaugmentation, the remediation of hydrocarbons is achieved by adding large amounts of petrophilic microbes, to a spill that cleave the hydrocarbons to carbon dioxide and water, without ‘tailings’. This is possible because the microbes use parts of the hydrocarbons to maintain their own metabolic process. Once the food source has been depleted, the remaining microbes then self-remediate. The result is clean water without traces of hydrocarbon. Toxins and pathogens are also removed.

Why are Nutrients important in bioaugmentation?
The ideal nutrient balance (pathway) required for hydrocarbon remediation is Carbon: Nitrogen: Phosphorus equals 100:10:4. In general, at least 1 ppm of ammonium nitrogen and 0.4 ppm of orthophosphate needs to be present. It is critical to control the inorganic nutrients in order to accelerate bacterial metabolism.
Nitrogen, which makes up nearly 15% of the molecular composition of a bacterial cell, is utilized by the bacteria to manufacture its cell walls, nucleic acids and proteins.

Phosphorus, in the form of inorganic phosphates, is used by the microorganisms to synthesize phospholipids and nucleic acids and for the energy transfer reactions of ATP. Enzymes that hydrolyze phosphate ester are present in nearly all organisms. Without adequate phosphorus, the ability of the bacteria to utilize hydrocarbons in the soil is sharply decreased.
Pathways can be influenced by further adjusting volumes of bio-nutrients. Variations in the signature will be evident while targeting can be achieved with this method.

Will the PETRO-CLEAR for hydrocarbons need to be exposed to oxygen?

Oxygen is the key. Four pounds of oxygen are required for one pound of hydrocarbon to be remediated. Much of this requirement will come from the atmosphere.
When the hydrocarbons are below the surface of the water, the microbes get their oxygen from the water. A minimum of 1.5 mg/L DO is required.  Surface agitation of air diffusion can be used to supply additional oxygen if required.

If the ground is compacted, the ground should be tilled or raked to allow as much oxygen as possible to permeate the soil. The hydrated Petro-Clear can then be sprayed over the tilled soil. For best results, a moisture content of 30 to 40% of the soil's holding capacity should be maintained (this equals around 9% for Texas sands, up to 23% for loams). The soil should be kept moist by adding fresh water.
If it cannot be tilled, high-pressure injection of diluted hydrogen peroxide (500 ppm final dose) can be added to the soil to aerate it.

Would a pilot test need to be conducted to determine if this strain of bacteria will feed on the hydrocarbon present?

Generally, no pilot test is needed on hydrocarbons. As long as the microbes come into contact with the contaminant, remediation is a straightforward process. Several strains of bacteria are used in our formulations. The problem is never with the bacteria strains, but rather with the inhibitory factors in the environment. Our company will provide technical support to help you identify factors that may be may be inhibiting your process and provide solutions to maximize the effectiveness of our products.

What if the area is high in sodium?
This formula is tolerant to 15%. It is used for bilge water and in marine applications.

How long will a typical clean up take?

This depends on the contaminant involved and it's concentration levels. Bioremediation bacteria may take from a few hours to several months or longer, depending upon the initial contaminant, level of contamination, temperature, the type of soil, the availability of oxygen in the area and the ability of the microbes to reach the contaminant. It can range anywhere from few hours for simple gasoline spills to several months for complicated crude oils.

Should I test for TPH when using bioaugmentation?
Soil analyses should be conducted periodically to evaluate the treatment program requirements. When measuring the effectiveness of the bioremediation process TPH analysis is not particularly accurate and may even indicate the presence of a gasoline or diesel fuel when none is there. 

A more exacting identification of hydrocarbons in soil and NAPLs can be made using fingerprinting methods such a gas chromatograph followed by a flame ionization detector (GC/FID) (Zemo, Bruyaand Graf, 1995).

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