Soil remediation is the removal of pesticides and other chemical and industrial pollutants that have leached into the soil and contaminate the ground water. Potassium permanganate (KMO4) is one of the chemicals that is pumped into the ground to disperse the contaminants by oxidizing them. Oxidation is the process of changing the chemistry of a compound by adding or subtracting oxygen atoms or groups of atoms called ions.
Carbon atoms can form long strongly bonded chains, important structures of life that are the subject of organic chemistry. In lay terms, potassium permanganate removes one carbon atom from a toxic compound and uses it to form carbon dioxide. Potassium permanganate works best at oxidizing alkenes, the simplest of which are the gases butene, ethene and propene; these all have a carbon-carbon double bond of atoms.
Traditionally, groundwater pollinated by volatile organic compounds have been extracted by a submersible vacuum pump. The extracted water is purified by forcing it through activated carbon, sand and other kinds of filters. High concentrations of pollutants can be removed by pump and treat technology, depending on the soil, but achieving concentrations of underground pollutants low enough to meet remediation standards is difficult.
In underground treatment, called in situ treatment, a 2 to 4 percent solution of potassium permanganate is injected directly into the source of pollution. Chemical oxidation may be used to treat contaminated soil, ground water and sediments in a variety of soils including clay and silt.
Potassium permanganate is especially useful in oxidizing tetrachloroethene (PCE), trichloroethene (TCE) and phenol, also called carbolic acid. PCE, used to dry clean clothing, is a common soil contaminant that is toxic at low levels; it is also dense, causing it to sink below the water table. PCE is more difficult to clean than oil spills. TCE is a toxic industrial solvent that is a common contaminate of drinking water that has been used as an anesthetic and analgesic. Phenol is also used as an industrial solvent.
Injecting potassium permanganate in situ is considered faster and less expensive than pump-and-treat technology. It does not yield large volumes of contaminated water that must be cleaned and recirculated. Hydrogen peroxide is also used to oxidize underground contaminants, but it is volatile and more costly than potassium permanganate.
Using potassium permanganate to oxidize soil contaminants may temporarily affect the ability of the aquifer to transmit fluids in local areas. The aquifer is a layer of permeable underground rock from which wells extract water.