Permanganate (MnO4) is a strong oxidant used in water treatment to control taste, odours, biological growth, zebra mussels, and to remove colour, manganese and iron. In addition, permanganate can be used to control the formation of disinfection by-products by oxidizing the organic precursors. In industrial waste treatment, permanganate is used for odour control, toxic pollutant destruction, bio-augmentation, and grease removal.
WHY IS IT IMPORTANT?
Although it is an effective treatment aid, residual permanganate is not desirable in the treated water. For this reason, dosing of permanganate needs to be carefully controlled and adjusted to provide just enough permanganate to achieve treatment goals but not in excess so that no residual remains in the water. Quick and reliable dose pacing of permanganate can be accomplished by monitoring its concentration in real time at a location downstream of the application point. Concentrations exceeding a pre-determined threshold at the monitoring point would indicate overdosing, and therefore dosing can be adjusted accordingly.
Permanganate is measured spectrophotometrically. Its concentration is directly proportional to absorbance at 525 nm due its colour (pink to violet).