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Potassium Permanganate For Water Treatment
#1
I received the following information from a Hoodlum in response to the thread on the effectiveness of uisng potassium permanganate for field water treatment. In that thread I had asked if anyone had any definitive information available since I had not found any in an extensive web search a couple of years ago. He told me the following is from an EPA publication, so I am quoting it exactly as he sent it to me:



For me, anyway, it settles the issue and my reading of this information is that potassium permanganate is not an effective water disinfection method.



Wally

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The following is reproduced from the EPA Guidance Manual [for] Alternative Disinfectants and Oxidants, April 1999.



I have underscored certain sections for emphasis.



(Begin cited material)



5. POTASSIUM PERMANGANATE



Potassium permanganate (KMnO4) is used primarily to control taste and odors, remove color, control biological growth in treatment plants, and remove iron and manganese. In a secondary role, potassium permanganate may be useful in controlling the formation of THMs and other DBPs by oxidizing precursors and reducing the demand for other disinfectants (Hazen and Sawyer, 1992). The mechanism of reduced DBPs may be as simple as moving the point of chlorine application further downstream in the treatment train using potassium permanganate to control taste and odors, color, algae, etc. instead of chlorine. Although potassium permanganate has many potential uses as an oxidant, it is a poor disinfectant.



5.4 Pathogen Inactivation and Disinfection Efficacy



Potassium permanganate is an oxidizing agent widely used throughout the water industry. While it is not considered a primary disinfectant, potassium permanganate has an effect on the development of a disinfection strategy by serving as an alternative to pre-chlorination or other oxidants at locations in a treatment plant where chemical oxidation is desired for control of color, taste and odor, and algae.



5.4.3 Use as a Disinfectant



A number of investigations have been performed to determine the relative capability of potassium permanganate as a disinfectant. The following sections contain a description of the disinfection efficiency of potassium permanganate in regards to bacteria, virus, and protozoa inactivation.



5.4.3.1 Bacteria Inactivation

High dosage rates were required to accomplish complete inactivation of bacteria in three studies. Early research showed that a dose of 2.5 mg/L was required for complete inactivation of coliform bacteria (Le Strat, 1944). In this study, water from the Marne River was dosed with potassium permanganate at concentrations of 0 to 2.5 mg/L. Following mixing, the samples were placed in a darkened room for 2 hours at a constant temperature of 19.8oC. Banerjea (1950) investigated the disinfectant ability of potassium permanganate on several

waterborne pathogenic microorganisms. The investigation studied Vibrio cholerae, Salm. typhi, and Bact. flexner. The results indicated that doses of 20 mg/L and contact times of 24 hours were necessary to deactivate these pathogens; however, even under these conditions the complete absence of Salm. typhi or Bact. flexner was not assured, even at a potassium permanganate concentration that turned the water an objectionable pink color. Results from a study conducted in 1976 at the Las Vegas Valley Water District/Southern Nevada System of Lake Mead water showed that complete removal of coliform bacteria were accomplished at doses of 1, 2, 3, 4, 5, and 6 mg/L (Hazen and Sawyer, 1992). Contact times of 30 minutes were provided with doses of 1 and 2 mg/L, and 10 minutes contact times were provided for higher dosages in this study.



5.4.3.2 Virus Inactivation



Potassium permanganate has been proven effective against certain viruses. A dose of 50 mg/L of potassium permanganate and a contact time of 2 hours was required for inactivation of poliovirus (strain MVA) (Hazen and Sawyer, 1992). A “potassium” permanganate dose of 5.0 mg/L and a contact time of 33 minutes was needed for 1-log inactivation of type 1 poliovirus (Yahya et al., 1990b). Tests showed a significantly higher inactivation rate at 23oC than at 7oC; however, there was no significant difference in activation rates at pH 6.0 and pH 8.0.



Potassium permanganate doses from 0.5 to 5 mg/L were capable of obtaining at least a 2 log inactivation of the surrogate virus, MS-2 bacteriophage with E. coli as the host bacterium (Yahya et al., 1989). Results showed that at pH 6.0 and 8.0, a 2-log inactivation occurred after a contact time of at least 52 minutes and a residual of 0.5 mg/L. At a residual of 5.0 mg/L, approximately 7 and 13 minutes were required for 2-log inactivation at pHs of 8.0 and 6.0, respectively. These results contradict the previously cited studies that potassium permanganate becomes more effective as the pH decreases.



5.4.3.3 Protozoa Inactivation



No information pertaining to protozoa inactivation by potassium permanganate is available in the literature. However, based on the other disinfectants discussed in this report, protozoa are significantly more resistant than viruses; therefore, it is likely that the dosages and contact times required for protozoa inactivation would be impractical.



(End cited material)



The complete text of Chapter 5 may be found through this link:

[url="http://66.102.7.104/search?q=cache:9dG41NkF1jwJ:www.epa.gov/safewater/mdbp/pdf/alter/chapt_5.pdf+potassium+permanganate+water+pollution&hl=en"]Link to Chapter 5.[/url]



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EDIT: link fixed
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