Bioremediation uses living organisms to remove or minimize contaminants from a polluted site. According to the US EPA, bioremediation is the treatment that uses natural organisms to break down chemicals into less toxic or non-toxic substances.
Bioremediation is used to treat human wastewater as well to remove agricultural chemicals (pesticides and fertilizers) that leach from the soil into groundwater. Selenium and arsen that are toxic can be removed from water through bioremediation.
Mercury as well can be removed from the ecosystem through bioremediation. Mercury is present in very small amounts in nature but is highly toxic because it accumulates in living tissues. Various species of bacteria can biotransform toxic mercury into non-toxic forms.
Pseudomonas aeruginosa, can transform Hg2+ to Hg, which is less toxic to humans. Alcanivorax borkumensis, produces surfactants that dissolve oil, while other bacteria break down oil into carbon dioxide. In optimal conditions, up to 80% of the non-volatile components of the oil can be degraded within a year of the spill.
Researchers have genetically engineered other bacteria to consume petroleum products; In fact, the first US patent application for a bioremediation application was for a genetically modified oil-eating bacteria.
There are a number of cost/effective benefits of bioremediation that can be implemented in inaccessible areas without excavation. For example, hydrocarbon spills (particularly oil spills) or certain chlorinated solvents can contaminate groundwater, which may be easier to treat with bioremediation than more conventional approaches.
Using prokaryotes for hydrocarbon bioremediation also has the advantage of breaking down contaminants at the molecular level, rather than simply chemically dispersing the contaminants.
One of the most famous and important examples of groundwater pollution in the US is the Love Canal tragedy in Niagara Falls, New York. It’s important because the Love Canal pollution disaster, along with similar environmental disasters at the time (Times Beach, Missouri, and Valley of Drums, Kentucky), helped create Superfund, a federal program established in 1980 aimed at helping the to identify and eliminate the worst hazardous chemical waste dumps in the US dug in the 1890s to generate hydroelectric power.
In the 1920s, Niagara Falls began dumping municipal waste into the Love Canal, and in the 1940s, the US military dumped about 21,000 tons of hazardous chemical waste, including the carcinogen benzene, dioxin and PCBs, into large metal drums at Love Canal and covered them with more clay.
In 1953 Hooker sold the land to Niagara Falls school board for $1 and included a clause in the purchase agreement describing the use of the land (filled with chemical waste) and exempting it from all claims for future damage freed from buried debris. The school board quickly built a public school on the site and surrounding land sold for a housing project that built approximately 200 homes along the banks of the the clay canopy and channel walls broke, damaging some metal barrels.
Finally, chemical waste seeped into people’s basements and metal barrels rose to the surface.Trees and gardens began to die; bicycle tires and the rubber soles of children’s shoes disintegrated into poisonous puddles.
From the 1950s until the late 1970s, local residents repeatedly complained of strange smells and substances appearing in their backyards. City officials investigated the area but took no action to address the issue. Local residents reported serious health problems, including high rates of miscarriage, birth defects, and chromosomal damage, but studies by the New York State Department of Health questioned that.
Finally, in 1978, President Carter declared a state of emergency for the Love Canal, making it the first man-made environmental issue to be so designated. The Love Canal incident has become a symbol of improperly stored chemical waste. contaminated soil, installing drainage pipes to collect contaminated groundwater for treatment, and covering it with clay and plastic.
Management Association for the resettlement of more than 1,000 families. New York state paid $98. million to the EPA and the US government paid $8 million for the Army contamination. The total cost was estimated at $275 million. The tragedy of The Love Canal helped start Superfund, which analyzed tens of thousands of hazardous waste sites across the US and eliminated hundreds of the worst. The environment is still cleaning up.