Liquid purification or separation – Processes – Treatment by living organism
Reexamination Certificate
1999-07-23
2001-07-31
Simmons, David A. (Department: 1724)
Liquid purification or separation
Processes
Treatment by living organism
C210S611000, C210S922000, C435S244000, C435S248000, C435S252100, C435S253300, C435S262500
Reexamination Certificate
active
06267888
ABSTRACT:
BACKGROUND OF THE INVENTION
(i) Field of the Invention
The present invention relates generally to cleanup of oil spills in a marine environment and, more particularly, to bioremediation or biological removal of floating oil through biodispersion.
(ii) Description of Related Art
Pollution of rivers, streams, harbors, bays, beaches and the open sea by hydrocarbon oil has increased tremendously in recent years. It is difficult to assess the quantity of polluting oil in any aqueous environment, since the oil generally transforms into the following four states on encountering water. These are a) as film on water, b) as solution in dissolved state, c) as emulsion of oil in water and d) in the form of tar balls. It is possible that only laser acoustic instruments may provide absolute values for the thickness of oil.
It has been reported that at least 10% of the volume of oil being transported through tankers and super tankers finds its way to estuaries and harbors polluting these environments. The volume of oil discharged through handling and transportation in addition results in a release of millions of gallons of oil into the sea. Although a major oil spill may occur in mid-ocean, actual harmful effects are felt only in the coastal regions and estuaries. The pollution of water by oil therefore, is not regarded as an oceanic problem but a coastal hazard.
Presently only two methods are generally regarded as safe in removing floating oil from any environment. One is physical removal of floating oil employing mechanical skimmer and suction devices of various types. The second one is bioremediation of contaminating oil. Although mechanical skimmers are effective in removing oil after oil spills of major or minor nature, the mechanical process does not remove all the oil completely and the residual oil once again finds its way to coastal regions or estuaries and beaches.
Bioremediation has been recognized as a technology to combat oil pollution through an environmentally friendly technique. The technology has been employed for shoreline clean up in Alaska after the accidental spill of 11 million gallons of crude oil spilled from the tanker EXXON VALDEZ in 1989. Results of massive experiments undertaken for the clean up of the shore line along the coast of Alaska by the representatives of U.S. Environmental Protection Administration (E.P.A) and those of EXXON Co. Houston have been published by both the U.S. E.P.A. and EXXON in 1991 and 1992, respectively. Thus a technology for shoreline clean up through bioremediation has been demonstrated which even today remains successful in a limited way.
Problems in harbors and ports are of a different nature and can not be subjected to the same technology. Bioremediation by addition of oil degrading microbes is often promoted as a treatment of floating spills, but this approach has not met with any documented success (Prince, 1998). Thus, the treatment for a floating oil spill requires a totally new approach.
SUMMARY AND OBJECTS OF THE INVENTION
The present overcomes the limitations described above with respect to the related art in that it removes floating oil in enclosed masses through a process identified as “biodispersion” which is followed by “bioutilization.”
The method of the present invention meets all of the requirements necessary for an oil spill cleanup technique, which is harmless to marine life of economic importance or otherwise. In addition the method has the advantage of preventing the extensive loss of bird life. The method explores the possibilities of pretreatment of ballast water and bilge water before its release by tankers and ships. The method can also be used for treatment of refinery effluents and for industrial waste water remediation.
In a first aspect, the present invention relates to a method for removal of free-floating oil from an aqueous environment by bio-dispersion and bio-utilization comprising the steps of:
(i) isolating a consortium or a strain of bacteria having an ability to utilize hydrocarbons as the only source of carbon;
(ii) admixing the bacteria with a hydrocarbon source to form an oleophilic suspension comprising a physiologically active bacterial culture of hydrocarbonoclastic species; and
(iii) applying the oleophilic suspension of the bacteria to a free floating oil in an aqueous environment to disperse and remove free-floating oil therefrom.
The bacterium is preferably obtained from the aqueous environment to be treated. In general, the suspension will comprise a multiple species or strains of bacteria. The species or strains of bacteria are advantageously derived from Pseudomonas, Phenylobacterium, Stenotrophomonas, Gluconobacter, Agrobacterium, Vibrio, Acinetobacter, or Micrococcus. yeasts or other genera can also be employed. Exemplary bacterial strains include
Pseudomonas pseudoalkaligenes, Phenylobacterium immobile, Stenotrophomonas maltophilia, Gluconobacter cerinus, Agrobacterium radiobacter
or
Pseudomonas alcaligenes.
It is also within the scope of the present invention to employ bacteria which have been genetically manipulated.
Suitable fatty substances for admixture with the bacteria in forming the oleophilic suspension include oleic acid, ricinic acid and other organic fatty acids available synthetically or through natural sources. Advantageously, the fatty substance is mixed with an oil such as diesel oil. The fatty substance can further comprise a oleophilic nutrients such as nitrogen and phosphorus in a state of micro-emulsion, a particularly preferred oleophilic nutrient being INIPOL®.
In addition to oil spills, the aqueous environment treated can further include, by way of example, ballast water, bilge water or refinery wastewater. Furthermore, the water can be saline or freshwater.
In a second aspect, the present invention relates to an oleophilic suspension comprising a fatty substance and a physiologically active bacterial culture of hydrocarbonoclastic bacteria for removing free floating oil from an aqueous environment by bio-dispersion followed by bio-utilization.
In a preferred embodiment, the physiologically active bacterial culture of hydrocarbonoclastic bacteria are indigenous to the aqueous environment. Exemplary bacteria are derived from Pseudomonas, Phenylobacterium, Stenotrophomonas, Gluconobacter, Agrobacterium, Vibrio, Acinetobacter, or Micrococcus. Exemplary species include
Pseudomonas pseudoalkaligenes, Phenylobacterium immobile, Stenotrophomonas maltophilia, Gluconobacter cerinus, Agrobacterium radiobacter
or
Pseudomonas alcaligenes.
The fatty substance may be oleic acid, ricinic acid or any other naturally occurring or synthetic fatty acids mixed in diesel oil or weathered oil or any other hydrocarbon oil. Furthermore, the fatty substance can further comprise an oleophilic nutrient, such as nitrogen and phosphorus, preferably as available in oleophilic nutrient INIPOL®.
Generally, the oleophilic suspension comprises between 1% and 15% by volume of the fatty substance dissolved in hydrocarbon oil.
In a third aspect, the present invention relates to a method of making an oleophilic suspension comprising a fatty substance, hydrocarbon oil and a physiologically active bacterial culture of hydrocarbonoclastic bacteria for removing free floating oil from an aqueous environment by bio-dispersion followed by bio-utilization, the method comprising the steps of:
(i) enriching hydrocarbonoclastic bacteria from a sample of water;
(ii) admixing the enriched hydrocarbonoclastic bacteria with a fatty substance and hydrocarbon oil to form a suspension; and
(iii) selecting those bacteria which are capable of bio-dispersion and bio-utilization.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The following definitions apply:
By “bacterium having an ability to utilize hydrocarbons as the only source of carbon” is meant hydrocarbonoclastic bacteria.
By “fatty substance” is meant fatty acids and/or oils which are otherwise compatible with the bacteria, which are oleophilic and easily miscible with hydrocarbon oil and which are capable of forming a suspension of the bacteria. The s
Hunton & Williams
Prince Fred
Simmons David A.
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