Bioremediation of Hydrocarbon Soil Contaminates
Bio-Genesis Tech International is a company located in Arizona. It has developed a synergistic group of microorganisms named GT1000-HC, which is a concentrated liquid blend of selected bacteria that have an exceptional capability to degrade a broad spectrum of hydrocarbons including light hydrocarbons, benzene, diesels, gasoline, BTEX and related fuels found in contaminated soil and water. The synergism of using their selectively adapted bacteria strains, produces a product with superior bio-kinetic response when compared with indigenous bacteria population. They also have the ability to digest short and long chain hydrocarbons, heavy tar types of oil and grease, coal tars, phenolic compounds, chlorinated organic solvents and many other toxic chemicals (Coukoulis, 2000).
These especially cultured organisms are nonpathogenic and use the petroleum products or other chemicals in the soil for both a carbon source and an energy source. They convert the toxic chemicals to cell mass and to carbon dioxide and water.
With bio-augmentation, studies have shown that this bacteria combination insures that a sufficient population will be provided to bioremediate most hydrocarbon spills. It is not the intent to provide a ready-made population to immediately digest the contaminants, but rather to provide an inoculum that will insure rapid bacterial growth. As the remediation project progresses, the population of petrophilic organisms will show up to a one thousand fold increase as they digest the contaminants.
In comparing bio-augmentation with natural degradation, the former greatly increases the rate of degradation. The microorganisms naturally present that can degrade petroleum products are usually present only in the upper few inches of soil and in low concentrations. These organisms are greatly diluted when mixed with a large amount of excavated soil. The dilution factor can be so large that it takes an excessively long time, if ever, to establish a working population of correct organisms.
Nitrogen is needed for amino acid, purine and pyrimidine biosynthesis and can be obtained by microorganisms from either inorganic or organic sources. The most commonly used nitrogen sources in bioremediation are ammonia and nitrate. Many of the bioremediation bacteria have two pathways for ammonia assimilation and which one functions depends on the ammonia concentration. They purposely keep the ammonia concentration high in order to allow the bacteria to utilize the simplest process.
When nitrate is utilized as the nitrogen source it is reduced to ammonia by a stepwise process. Nitrate is first reduced to nitrite by molybdenum containing enzyme and then to ammonia by nitrogen fixing bacteria. In addition, phosphorus (in the form of phosphate) is utilized by soil microorganisms primarily to synthesize phospholipids and nucleic acids (DNA and RNA).
In addition to nitrogen and phosphorus, a variety of minerals are universally required, such as potassium, calcium, magnesium and iron. Many other elements are required only in trace amounts. These include zinc, copper, cobalt, manganese and molybdenum. These metals function in enzymes or coenzymes. Although none of the microorganisms in this particular bioremediation formula require organic growth factors, it has been observed that organic growth factors such as B vitamins greatly stimulate growth and bio-degradation. The bacteria in this formula were all isolated from the soil and laboratory studies have shown that the optimum temperature of the soil will be maintained as close to 28 Celsius as possible. Similar studies have shown that soil moisture should be maintained at 15-20% moisture.
Bioremediation of hydrocarbon, contaminated soil is best achieved by bio-augmentation with a specified formula of bacteria such as those in this formula. For the most successful and rapid bioremediation, the oxygen and nutrient concentrations, as well as temperature must be carefully controlled. Bioremediation holds promise as an effective intervention for this type of contaminated soils. The bottom line is that extensive, stringently validated field studies show that bioaugmentation strategies are crucial to succeed in using this concept as a tool for in-situ bioremediation.
These especially cultured organisms are nonpathogenic and use the petroleum products or other chemicals in the soil for both a carbon source and an energy source. They convert the toxic chemicals to cell mass and to carbon dioxide and water.
With bio-augmentation, studies have shown that this bacteria combination insures that a sufficient population will be provided to bioremediate most hydrocarbon spills. It is not the intent to provide a ready-made population to immediately digest the contaminants, but rather to provide an inoculum that will insure rapid bacterial growth. As the remediation project progresses, the population of petrophilic organisms will show up to a one thousand fold increase as they digest the contaminants.
In comparing bio-augmentation with natural degradation, the former greatly increases the rate of degradation. The microorganisms naturally present that can degrade petroleum products are usually present only in the upper few inches of soil and in low concentrations. These organisms are greatly diluted when mixed with a large amount of excavated soil. The dilution factor can be so large that it takes an excessively long time, if ever, to establish a working population of correct organisms.
Nitrogen is needed for amino acid, purine and pyrimidine biosynthesis and can be obtained by microorganisms from either inorganic or organic sources. The most commonly used nitrogen sources in bioremediation are ammonia and nitrate. Many of the bioremediation bacteria have two pathways for ammonia assimilation and which one functions depends on the ammonia concentration. They purposely keep the ammonia concentration high in order to allow the bacteria to utilize the simplest process.
When nitrate is utilized as the nitrogen source it is reduced to ammonia by a stepwise process. Nitrate is first reduced to nitrite by molybdenum containing enzyme and then to ammonia by nitrogen fixing bacteria. In addition, phosphorus (in the form of phosphate) is utilized by soil microorganisms primarily to synthesize phospholipids and nucleic acids (DNA and RNA).
In addition to nitrogen and phosphorus, a variety of minerals are universally required, such as potassium, calcium, magnesium and iron. Many other elements are required only in trace amounts. These include zinc, copper, cobalt, manganese and molybdenum. These metals function in enzymes or coenzymes. Although none of the microorganisms in this particular bioremediation formula require organic growth factors, it has been observed that organic growth factors such as B vitamins greatly stimulate growth and bio-degradation. The bacteria in this formula were all isolated from the soil and laboratory studies have shown that the optimum temperature of the soil will be maintained as close to 28 Celsius as possible. Similar studies have shown that soil moisture should be maintained at 15-20% moisture.
Bioremediation of hydrocarbon, contaminated soil is best achieved by bio-augmentation with a specified formula of bacteria such as those in this formula. For the most successful and rapid bioremediation, the oxygen and nutrient concentrations, as well as temperature must be carefully controlled. Bioremediation holds promise as an effective intervention for this type of contaminated soils. The bottom line is that extensive, stringently validated field studies show that bioaugmentation strategies are crucial to succeed in using this concept as a tool for in-situ bioremediation.