Bioremediation –an environmental cleaning application with various techniques that neutralizes contaminates in soil and water.
Use of Surfactants in Bioremediation are categorized by the following:
Soil Bioremediation of Petroleum Contamination
Bioremediation of Water Contamination
Remediation of Metals
September 2015 – Surfactant Bioremediation’s advancing technologies are now in a position to replace current methods of bioremediation that are environmentally invasive.
Petroleum-derived contaminants constitute one of the most prevalent sources of environmental degradation in the industrialized world. In large concentrations, the hydrocarbon molecules that make up crude oil and petroleum products are highly toxic to the environment. Petroleum causes most of the land, water and air pollution.
In both leading world economies and developing countries, petroleum provides the primary source of energy for industry. Surfactant Bioremediation decreases the levels of toxins in the environment by hydrocarbon degradation.
In this new age of manufacturing, petroleum is also used to produce synthetic products such as chemicals, paints, pesticides, batteries, and fertilizers. The contamination of soil and water is also due to these chemical compounds being released into the environment. These chemical compounds like benzene or toluene can cause headaches and dizziness and could have long-term effects on the brain, liver and kidneys. Another factor in pollution are the toxins released into the environment by the same chemicals being used to clean hydrocarbons. These synthetic chemicals used for cleaning are adding to the degradation of ecological systems.
Heavy metal soil contamination is produced from industrial plant emissions, ore waste from mining, disposal of high metal wastes, leaded gasoline and paints, land application of fertilizers, animal manures, sewage sludge, pesticides, wastewater irrigation, coal combustion residues, and spillage of petrochemicals. Heavy metal soil contamination is present in old landfill sites, old farming land that used insecticides containing arsenic, and fields that had past applications of wastewater and treatments of municipal sludge. Mining facilities, industrial areas where chemicals have been dumped on the ground and in our waterways, and in areas downwind from manufacturing facilities are also contaminated with metals.
Recent examples of the health and environmental consequences of metal contamination include arsenic in drinking water and metal uptake by agricultural crops.
Contamination of water from gasoline and diesel fuel is a common occurrence. These petroleum-based fuels are leaking from underground storage tanks into our water supplies. Gasoline consists of a mixture of hydrocarbons that dissolve in water. Excessive metal content in soils can impact air, surface water, and groundwater quality. Arsenic, Cadmium, Chromium, Copper, Lead, Mercury, Nickel, Selenium, and Zinc are the main culprits.
Restoring Environmental Health
Surfactant Biological Bioremediation is now a potent tool in decreasing the levels of contaminants in soil. Crude oil (petroleum/hydrocarbons) is considered to be of biological origin, the result of several biological natural processes. Therefore, petroleum is delineated from microbes. Based on scientific facts, the biodegradation of petroleum has always existed. This is the reason why microbes degrade petroleum naturally. Rhamnolipid is a chemical that is secreted from the bacterium pseudomonas aeruginosa. Rhamnolipid is a Surfactant. Biological or Surfactant Bioremediation is using microorganisms and their secreted chemicals to basically break apart hydrocarbons. Naturally, microorganisms are a catalyst in limiting hazardous contaminants in the environment by breaking apart non-toxic byproducts during natural soil bioremediation. So to conclude, microorganisms, natural or synthetic, can breakdown hydrocarbons into non–toxic components (carbon dioxide and water).
Rhamnolipid Biological Bioremediation is widely considered safe and non-invasive to the environment. Most importantly, this is an on site application (in-situ) which can be applied to both water and soil. This process is less expensive and less environmentally disruptive (as to not impact the site with more toxins) than many current physical or chemical methods of bioremediation. Next to expense, another factor in bioremediation is what level of residual contaminant after application of bioremediation is acceptable whether it organic or synthetic. Rhamnolipid Surfactant Bioremediation leaves no residual surfactant and the same amount of Rhamnolipid that is left is natural. Rhamnolipid is ubiquitous, naturally produced they are found in streams, in soil and in our homes.
Rhamnolipid when mixed with Chitosan and anther natural ingredient creates a flocculent that binds to and raises contaminates in water to the top of the water body. Once contaminates are floating in water, they can be easily filtered out as opposed to the old way of vacuuming waterbeds.
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 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 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.[/span6]
The Use of Rhamnolipids for Bioremediation
Rhamnolipids have well known applications for the remediation of hydrocarbon contamination in soil and water. They are documented to facilitate the cleanup of toxic heavy metals in soil and substrate. They have the advantage that they can treat the problems in situ rather than whole scale removal of contaminated soils and burning or sequestration. An early use of rhamnolipids was the in the Exxon Valdez cleanup based on research initiated in Zagreb. There is active research into the use of rhamnolipids for remediation including such universities as University of Arizona, Dartmouth College, Concordia and others around the world.
Rhamolipid Bioremedation Mechanisms – Hydrocarbon Contamination Remediation
Rhamnolipids are found naturally and at virtually every hydrocarbon contamination site. Over time, they will be a factor in the natural remediation of the spill. The application of additional rhamnolipids will accelerate the breakdown and metabolism of rhamnolipids to minimize the long-term effects of the spill and accelerate restoration to a natural state.
There are four mechanisms that make rhamnolipids effective in hydrocarbon contamination remediation such as oil spills. First the rhamnolipids function as an emulsifier to break apart the fluid hydrocarbons. This minimizes the mechanical effects of the spill such as fouling bird feathers and blocking oxygen transport. This emulsification allows other natural processes to aid the breakdown of the hydrocarbons.
Second, as a surfactant, the rhamnolipids help transport the hydrocarbons away from being locked up in rock and soil pores.
Third, the rhamnolipids facilitate the metabolism of the hydrocarbons by certain gram-negative bacteria such as Pseudomonas aerugninosa by attaching to the cell walls of the bacteria and then facilitating the transport of the hydrocarbons into the cell where they are metabolized.
Fourth, the rhamnolipids stimulate the growth of these gram-negative bacteria and protect them from attack by allowing the bacteria to form a protective layer for clusters of these bacteria through which nutrients can flow. It is called a biofilm.
Since the rhamnolipids naturally occur at the site and since there are no harmful products of the natural breakdown of the rhamnolipids, rhamnolipids are a natural solution to hydrocarbon remediation. In situ rhamnolipid bioremediation is effective in soils, substrates, and fresh and salt water.
Toxic and Heavy Metal Remediation
Rhamnolipids have been documented to bind up metal contamination. This binding, called complexation, is effective for a whole range of metals including cadmium, lead, and zinc using mono-rhamnolipids. Other metals that rhamnolipids potentially can treat are aluminum, copper, mercury, cobalt and others. Complexation makes the metal unavailable for other reactions and therefore minimizes the toxicity of the metal.
Rhamnolipids are also used to help the adsorption of certain pollutants into certain plants. This allows the removal of the pollutants by harvesting the plant and then processing it to extract the pollutant.
Because rhamnolipids are a surfactant, they also provide the mechanism for transporting through the soil and substrate to be collected downstream or pumped out via a well. The effectively of the rhamnolipids is dependent on pH and on concentration. Generally analytical experiments will need to be run on samples to determine the best application. Since the rhamnolipids are naturally occurring, albeit in much less concentration, the rhamnolipid solution is a natural solution to metal contamination.