"Remediate" means to solve a problem, and "bio-remediate"" means to use biological organisms to break down harmful chemicals and pollutants in order to return the environment to its original natural condition. This would include an environmental problem such as contaminated soil or groundwater.
In a non-polluted environment, bacteria, fungi, protists, and other microorganisms are constantly at work breaking down organic matter. What would occur if an organic pollutant such as oil contaminated this environment? Some of the microorganisms would die, while others capable of eating the organic pollution would survive. Bioremediation works by providing these pollution-eating organisms with fertilizer, oxygen, and other conditions that encourage their rapid growth. These organisms would then be able to break down the organic pollutant at a correspondingly faster rate. In fact, bioremediation is often used to help clean up oil spills.
Bioremediation of a contaminated site typically works in one of two ways. In the case described above, ways are found to enhance the growth of whatever pollution-eating microbes might already be living at the contaminated site. In the second, specialized microbes are added to degrade the contaminants.
Bioremediation provides a good cleanup strategy for some types of pollution, but as you might expect, it will not work for all. For example, bioremediation may not provide a feasible strategy at sites with high concentrations of chemicals that are toxic to most microorganisms. These chemicals include metals such as cadmium or lead, and salts such as sodium chloride.
Nonetheless, bioremediation provides a technique for cleaning up pollution by enhancing the same biodegradation processes that occur in nature. Depending on the site and its contaminants, bioremediation may be safer and less expensive than alternative solutions such as incineration or landfilling of the contaminated materials. It also has the advantage of treating the contamination in place so that large quantities of soil, sediment or water do not have to be dug up or pumped out of the ground for treatment.
What Is Bioremediation?
Bioremediation is the use of microbes to clean up contaminated soil and groundwater. Microbes are very small organisms, such as bacteria, that live naturally in the environment. Bioremediation stimulates the growth of certain microbes that use contaminants as a source of food and energy. Contaminants treated using bioremediation include oil and other petroleum products, solvents, and pesticides.

How does bioremediation work:-
For the process of bioremediation, it is necessary that microorganisms should be healthy and active so that they can perform their duty efficiently.
Bioremediation can take place in two conditions that are aerobic and anaerobic conditions. In anaerobic condition, microbes need oxygen to perform their duty. If they will get oxygen in sufficient amount they will be able to easily convert the contaminants and toxins into water and carbon. In anaerobic conditions, microbes do the activity in the absence of oxygen. Chemical compounds which are present in the soil can be decomposed by bacteria under anaerobic conditions. As a result energy produces which is used by the microbes.

#2. Genetic engineering has become integrated with bioremediation since many microbes can be artificially designed which can consume the toxic waste and pollutants that are not usually taken in by normal microbes. This is done by first genetically altering the sequence of the desired microbe and enhancing its ability to digest the toxic particles of the pollutant or genetically modifying a new microbe that has an ability to take in, consume, and digest the pollutants. Thus, microorganisms are designed specifically for bioremediation.
A recent advancement is the genetically modified bacterium Deinococcus radiodurans that is the most radio-resistant organism ever known. It can consume high amounts of radioactive ionic mercury and toluene from radioactive waste.
As record of the year of 2000, three trillion liters of ground water has been contaminated by constantly leaking radioactive waste generated in minute quantities in the U.S. during the cold war. The bioremediation technique is being developed which is based on the radiation-resistant bacterium Deinococcus radiodurans, which has been successfully engineered to express bioremediation functions.
#7. Bioremediation may have been discovered by the Romans, but microbiologists have studied the process only since the 1940s. The Exxon Valdez oil spill in 1989 in Prince William Sound, Alaska, was the genesis of global attention to this process. Since 1989, bioremediation has become a technology that is discussed, applied, and considered in many different circumstances. The history of bioremediation in response to the Exxon Valdez oil spill can be divided into three development periods: the "Courtship" period until 1989, the "Honeymoon" period from 1989 until 1991, and the "Establishment" period since 1992.
Courtship Period (Pre-1989)
The first period of bioremediation, called the "Courtship" Period, was basically a period dedicated to research. This was when bioremediation was little known outside the microbiology or hazardous waste community. A number of scientific papers and articles on this topic were published during the 1970s and 1980s. Several studies following major oil spills like the Amoco Cadiz spill measured oil degradation in the environment and confirmed laboratory research.
Honeymoon Period (1989-1991)
Between 1989 and 1991, bioremediation experienced its "Honeymoon" period, receiving widespread attention and interest.
The Exxon Valdez incident was an oil spill in 1989, in Prince William Sound, Alaska, that revolutionized what the world knew about bioremediation. During the first weeks after the spill, responders flooded in with offers to help clean up the oil that had spread over 500 km of coastline in Prince William Sound. Bioremediation agents of all kinds were used; however, testing and evaluation had not yet been conducted. A committee of both Federal and State government authorities was then established to develop a protocol for evaluating these agents and to select the most promising for future testing and development. Prior to 1989, there were no documented uses of this technology on marine oil spills. During the 1990s, bioremediation was used (on a trial basis) at a total of four US spills: Prall’s Island in New Jersey, Seal Beach in California, and the Apex barges and Mega Borg spills in the Gulf of Mexico. The honeymoon period for bioremediation then started to end in late 1990 and 1991
Establishment Period (Since 1992)
The period since 1992 may be called the "Establishment" period. During this time, bioremediation has achieved a certain level of acceptance, with more realistic expectations than earlier, but the level of interest and attention has decreased considerably. Everyone is not sure about how toxic the various fertilizer formulatations or microbial products are, and questions about their effectiveness. Most proposals to use bioremediation in open coastal environments are now accompanied by some type of monitoring program to determine whether the technique is accelerating oil degradation above background rates. In the case of a large spill, such as the Exxon Valdez, a pilot test can be conducted before the responsible authorities commit to the use of bioremediation on a large scale. However, the expense and effort required to establish a monitoring program may prevent the use of bioremediation at smaller spill
The process of bioremediation was invented by George M. Robinson in the 1960s. While serving as the Assistant County Petroleum Engineer for Santa Maria, California, he spent his spare time experimenting with dirty jars and the abandoned oil sumps of the Cat Canyon Oil Field. He then organized the first large-scale microbial cleanup of an oil spill in 1968. After, Robinson used bioremediation to complete the clean up of spills, sewage, leach fields and as well as odor and pest control, sewage, leach fields and as well as odor and pest control
One person who is known for his amazing contribution to bioremediation is Ananda Chakrabarty. Dr. Ananda M. Chakrabarty, Amrita’s Senior Science Mentor, is the global domain expert relating to how bacterial proteins effectively combat cancers, parasites, and viruses in the human body. In the 1970s, Ananda and his colleagues at General Electric discovered a strain of bacteria that is able to degrade some components in crude oil. He obtained this strain by isolating a Pseudomonas from a soil filled with.
#4. Overall, the only social issue bioremediation faces as of today are members of a community or businesses near the operation site overhearing the use of construction apparatuses which includes mixers, pumps, and other equipment to clean up the site https://clu-in.org/download/Citizens/a_citizens_guide_to_bioremediation.pdf

Bioremediation does require for DNA in bacteria to be genetically altered in order to properly do its job and clean the contamination. This does impose ethical issues because some people believe that since it is not a naturally occuring modification, it could upset the natural environment.
Though the fact that the microbes are genetically altered to better rid soil or water of contamination, it is highly improbable that the microbes will spread the contamination anywhere. The microbes grow as they eat the waste or pollutants, and when they have cleaned up the contaminates in the soil or water they they tend to die http://www.bioteach.ubc.ca/Journal/V02I01/bioremediation.pdf legal issues surrounding bioremediation include property rights of the site where bioremediation may be used and the consent of the community. There are two major acts that help regulate bioremediation:
Research Conservation and Recovery Act
The RCRA was brought about in 1976 to help identify toxic waste that is dangerous to the enviroment's health. Disposal of any hazardous material must go through the RCRA and follow through the standards and procedures.
Comprehensive Environmental Response, Compensation and Recovery Act
The CERCRA, created in 1986, was to provide the EPA with the authority to clean up the toxic sites. Those who create, store, or anything of waste is held responsible for its clean up. CERCRA provides an extreme incentive for this off. http://www.bioteach.ubc.ca/Journal/V02I01/bioremediation.pdf http://science.energy.gov/~/media/grants/pdf/foas/2000/00-21.pdf
The Economic Impact
The discovery of bioremediation had a huge economic effect on the world. Bioremediation has been proven to be less expensive than alternative solutions such as incineration or landfilling, that are also used for clean-up of contaminated and hazardous waste http://pac.iupac.org/publications/pac/pdf/2001/pdf/7307x1163.pdf

Advantages
• Bioremediation is a natural process and is therefore viewed by the public as an acceptable waste treatment process for contaminated material. Microbes are able to degrade the contaminant. When the contaminant is degraded, the biodegradative population decreases. Carbon dioxide, water, and cell biomass are the results of these transformations into harmless products.
• For the complete destruction of contaminants, bioremediation can be used. Harmless products are produced from converting them from previous dangerous materials. The liability associated with treatment and disposal of contaminated material is eliminated.
• The complete destruction of target pollutants is possible without having to move the contaminants from one environmental surrounding to another.
• Bioremediation can often be taken care of on site, without causing a major interruption of normal activities. This also eliminates the need to transport waste off site and the possible threats to human health and the environment that can arise during transportation.
• For clean-up of hazardous waste, bioremediation provides the most cost effective and natural way to clean up an effected area
Disadvantages
• Not all compounds are biodegradable, which limits bioremediation use in many ways.
• There are some apprehensions that the products of biodegradation may be more toxic than the original material.
• There are many important site factors required for completion of bioremediation such as the presence of metabolically capable microbial populations, and appropriate levels of nutrients and contaminants. Biological processes are highly specific.
• It is difficult to infer from bench and studies to perform field operations of bioremediation.
• Bioremediation technologies require much research. This is appropriate for sites with intricate mixtures of contaminants that are not evenly distributed in the environment. Solids, liquids, and gases are ways contaminants can be present.
• Unlike excavation, removal of soil or incineration, bioremediation is a process that requires more time.
• There is no definition of “clean”, evaluating performance of bioremediation is difficult, and there are no acceptable endpoints for bioremediation treatments. There are many concerns that bioremediation isn't the most effective way to go. http://pac.iupac.org/publications/pac/pdf/2001/pdf/7307x1163.pdf #3. http://matts-bioremediation.tripod.com/id4.html
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