Environmental Cleanup
Rhamnolipids for BioRemediation
Remediation is process of restoring the environment after being disturbed or polluted by mankind. Bioremediation is accomplishing the remediation with natural “green” products.
Traditional Remediation
Traditional environmental remediation methods include the removal of the contaminated soil or sediment and then partially treating it off site by incineration or chemical processing and then storage in a landfill. This ex-situ process is expensive as fewer landfills are available. Without the chemical treatment it is not a permanent solution.
Metal chelators such as EDTA (ethylenediaminetetraacetic acid), which bind to metals in soil, have been widely used. Unfortunately EDTA, although effective, has been found to be a persistent organic pollutant.
Traditional remediation methods for polluted water include pumping and transporting it to a processing facility where the water is treated, filtered, and purified using reverse osmosis, and perhaps distilled. The resulting concentrated waste is either incinerated or stored in a special landfill.
Ultimately the problem is that the pollutant migrates though the aquifer.
Bioremediation
Bioremediation is the process used to clean soil or groundwater contaminated by heavy metals or petroleum products into non-hazardous substances. It works using the same biodegradation processes that would occur in nature if the area was not polluted. Bioremediation is generally cheaper, quicker and easier than traditional methods. Rhamnolipids are effective in dissolving petrochemicals and other oils and fats, as well as chelating toxic and heavy metals.
Soil Washing Using Rhamnolipids
A major problem facing the environment today is one of discarded Hydrocarbons. These are fuels and oils, which have been introduced into the environment, causing contamination of the surrounding areas. The most common form of pollution is oil discharge from automobiles and heavy machinery. Oil spills, whether they are small oil spots on our driveway pavement, seeped into soil, or large oil spills on land, the coast, or the sea, they are hard to eradicate.
Rhamnolipids are a natural surfactant with emulsifying properties. These biodegradable, non-toxic, natural ‘green’ surfactants dissolve environmentally unfriendly substances such as oil, grease, gasoline, and diesel fuels.
Rhamnolipids can be used in-situ using 2 methodologies. In the first, where there is a way of collecting the groundwater from the target watershed or aquifer, the rhamnolipid solution can be sprayed on the target soil and allowed to percolate through the soil. The rhamnolipids dissolve the petrochemicals (or metals) into the water and the solution drains from the area, it is collected and processed, potentially recovering the hydrocarbons and metals for commercial use. This method is known as surfactant enhanced aquifer remediation (SEAR). As some surfactant is likely to remain in the soil, it is best to use a biodegradable natural surfactant such as rhamnolipid.
The second method is used where it is not possible to collect the resulting solution. In this method, the rhamnolipid solution is sprayed on the polluted surfaces to emulsify the petrochemicals. This allows naturally occurring bacteria such as Pseudomonas aeruginosa to metabolize the hydrocarbons into useful by-products normally found in the environment and metabolized by higher life forms. To speed the process, the area may be optionally inoculated with the bacteria.
Recent studies indicate that rhamnolipids not only emulsify the hydrocarbons, but also aid gram-negative bacteria in metabolizing the hydrocarbons by aiding passing the hydrocarbons through the cell wall. This enhancement is effective in much lower concentrations than the Critical Micelle Concentration (CMC) normally needed for effective emulsification.
Prince William Sound Oil Spill
Following the major oil spill in Alaska's Prince William Sound, the Environmental Protection Agency brought in natural oil-eating bacteria to help clean up the spill. Follow-up studies suggest that the rhamnolipids dissolved the oil, cleaning up the soiled beaches better than using high-pressure hoses and detergents. "It was almost as if we had brought in fresh rock," stated the EPA's project manager after visiting the site. Using the rhamnolipids has the advantage of not mechanically disturbing the sand and beach rock and not leaving the harmful residue of the detergents.
It now should be recognized that the success of this process was in part due to the rhamnolipid metabolic enhancement mentioned just above. Relatively small concentrations of rhamnolipids are far more effective than previously thought.
Hazardous Metal Contamination
Hazardous Metals contaminating soils and water are an extreme environmental problem and huge health risk for the human population. Lead, cadmium, mercury are especially toxic.
Research has shown that the anionic rhamnolipids are particularly effective in binding to cationic metals in a process called complexation. It has been shown that the more toxic metals listed above have some of the highest affinities for complexation by rhamnolipids.
This means that rhamnolipids can be used to clean up hazardous metals in soils using the soil washing technique above as well as remove these metals from factory wastes.
In places where it is not feasible to collect the percolated water, it may be possible to take advantage of rhamnolipids ability to increase absorption of metals to a crop planted specifically for the purpose of harvesting the crop and extracting the metal.
Biosurfactants Vs. Synthetic Surfactants
Synthetic surfactants are manmade and mostly derived from petroleum products. They have been widely used in industry for many years because they work and were relatively inexpensive. Synthetic surfactants have serious ecological impacts, both by depleting a non-renewal resource and by leaving non-biodegradable and harmful by-products.
Biosurfactants are natural products created by natural processes with little or no environmental impact. They eliminate the undesirable materials. Biosurfactants often are higher foaming and work better at extreme temperatures than synthetic surfactants.
Rhamnolipid, Inc.
Rhamnolipid, Inc. is a company that specializes in producing, purifying, and formulating rhamnolipids for the bioremediation industry.