permanganate is the chemical compound KMnO4. In this salt, manganese is
in the +7 oxidation state. The salt is also known as "permanganate of
potash." The permanganate ion is a strong oxidizing agent. It dissolves
in water to give deep purple solutions, evaporation of which gives prismatic
purplish-black glistening crystals. In 2000, worldwide production was
estimated at 30,000 t/a.
greensand is another common treatment method for removing sulfur from
drinking water. It is usually recommended for water that contains less
than 6.0 mg/l hydrogen sulfide. A manganese greensand filter has a special
coating that oxidizes hydrogen sulfide gas to solid sulfur particles,
which are filtered. When all of the manganese oxide is consumed, the greensand
is regenerated with potassium permanganate. Potassium permanganate is
a purple oxidizing chemical that is added to the untreated water to maintain
the manganese greensand filter. To work properly, the greensand must be
regenerated at periodic intervals based on water usage and contaminant
concentration. When greensand is used to treat high concentrations of
hydrogen sulfide, more frequent regeneration is required.
an oxidant, potassium permanganate can act as a disinfectant. For example,
dilute solutions are used as a treatment for canker sores (ulcers), disinfectant
for the hands and treatment for mild pompholyx, dermatitis, and fungal
infections of the hands or feet. Potassium permanganate, obtainable at
pool supply stores, is used in rural areas to remove iron and hydrogen
sulfide (rotten egg smell) from well and waste water.
not highly toxic, concentrated solutions of potassium permanganate can
be harmful to the skin. Permanganate is a strong oxidizer similar to chlorine,
so it can cause irritation or burns with direct contact to skin. However,
very little or no permanganate should reach the filtered water from a
greensand system. The permanganate is only used to backwash and clean
the greensand filter media. Excess permanganate is flushed out before
raw water is re-routed through the distribution system. A special double
rinse cycle makes sure the filter bed is free of any permanganate residual.