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Biological Treatment Mike Lawliss
Bioremediation The use of bacteria and other microorganisms to break down hazardous waste into relatively harmless components
In bioremediation, the contaminated site is exposed to an army of microorganisms, which gobble up the poisons such as petroleum and other hydrocarbons and leave behind harmless substances, such as carbon dioscid, water, and chlorides. Conditions at the hazardous waste site are modified so that the desired bacteria will thrive in large enough numbers to be effective.
Phytoremediation The use of plants to absorb and accumulate hazardous materials from the soil
In phytoremediation, plant species known to remove specific hazardous materials from the soil are grown on the contaminated site. As the roots penetrate the soil, they selectively absorb the toxins, which accumulate in both root and shoot tissues. Specific plants are known to remove such hazardous materials as TNT, radioactive strontium and uranium, selenium, lead, and other heavy metals. Three species of marsh plants that degrade herbicides and pesticides have been identified.
Some limitations to phytoremediation include the fact that plants cannot remove contaminants present in the soil deeper than the roots normally grow. Also, there is concern that insects and other animals might eat the plants, thereby introducing the toxins into the food web.
Enivironmental engineers might pump air through the soil and add a few soil nutrients such as phosphorus and nitrongen. They might install a drainage system to pipe any contaminated water that leaches through the soil back to the surface for another exposure to the bacteria
