I do not think there is any relation. What type of relation do you mean/

Both test are used for estimating pollution load in water. Both tests releases oxygen in water during process reaction. Both are disinfectants. There must be some relation in their values.

Permanganate value (PV)

Potassium permanganate (KMnO4), a powerful oxidant, is rarely applied in water treatment for the purpose of disinfection. It is sufficiently. effective against cholera bacteria, but not against other pathogenic germs. A dose of 1 to 5 ppm KMnO4 is recommended for application. It must be noted, though, that it creates a purplebrown precipitate which coats the walls of the tank. It cannot be removed easily.

In recent years, potassium permanganate has gained steadily in the application in pretreatment since it has proved effective at:

a) removing objectionable odor and taste by means of oxidation of organic material, hydrogen sulfide;

b) preventing algal growth;

c) removing iron and manganese compounds by means of oxidation and subsequent separation by filtration.

Potassium permanganate can be used to quantitatively determine the total oxidisable organic material in an aqueous sample. The value determined is known as the permanganate value. It is also a measure of the total oxidizable material in the sample which is likely to be mainly made up of organic compounds. You can find the PV by mixing the water with excess acidified potassium manganite (VII) solution and keeping it warm for some time to allow the oxidation to take place. The concentration of manganite (VII) remaining is found by adding solid potassium iodide and titrating the liberated iodine with sodium thiosulphate solution. A distilled water sample is treated in exactly the same way to act as a blank. The blank titre minus sample titre is now a measure of the oxidisable material in the water.

Chlorine Demand

Chlorine of any type must be added to water in closely controlled concentrations which depend on the characteristics of the water. As the use of dry chemicals doesn't always permit sufficient accuracy of dosing, solutions are preferred. Chlorine is usually added to the water for disinfection at the end of the treatment process. This allows the most effective treatment at the lowest level of chlorine application. Measurements of the chlorine demand and residual chlorine must be taken to assure that sufficient free chlorine is available to accomplish disinfection.

Water characteristics and, hence, the chlorine demand may vary due to external influences (e.g., rainy season, etc.). It is therefore necessary to monitor the water quality from time to time, at the points of consumption in cases where the chlorine dosage is fixed. The objective of disinfection via chlorination can only be obtained if the chlorine dosage is adjusted to the changed water characteristics.

In the field, the chlorine demand of water of a given quality can be determined as follows: One lifer samples of the water are taken. Chlorine solution of a known concentration is added and mixed with the water. After 30 minutes of contact time, the residual chlorine content is measured. The difference to the amount added then yields the chlorine consumption.

Chlorine demand = chlorine consumption + desired residual

As the chlorine reacts with bacteria and chemicals in the water, some of the chlorine is used up. The amount of chlorine used up by reacting with substances in the water is known as the chlorine demand. If nothing reacts with the chlorine (as would be the case in distilled water), then the chlorine demand is zero. However, in most cases the operator should count on some of the chlorine dose being used up when it reacts with substances in the water.

Usually 1% chlorine solutions are applied. The chlorine flow is set such that a chlorine residual level of between 0.1 and 0.3 mg/l is obtained. Higher levels are recommended if rapid recontamination is likely.

Colorimetric tests are employed to determine total chlorine residuals. Chemical agents (DPD or OT method) are used which are oxidized by chlorine to produce a colored complex, the intensity of which is proportional to the amount of chlorine present. Reading the colors and matching color standards by means of a comparator and disks, gives the amount of free, available, and residual chlorine. Various simple test kits are commercially available, using permanent glass and containing DPD reagents in liquid or compressed tablet form.

Calculation of the required amount of chlorine: Given the amount or flow of water to be chlorinated, the chlorine demand and the strength of the chlorine solution to be used, the necessary amount of solution can be calculated as follows:

chlorine demand (g/m³) x amount of water to be treated (m³/h) = required amount of active chlorine per hour (g/h); required amount of chlorine solution per hour (l/h) = required active chlorine per hour (g/h) divided by active chlorine per liter of solution (g/a)

It must be noted that the manufacturers usually express the available chlorine con. tent in terms of percent weight (g/100 g). In the field, however, it is often expressed in terms of percent volume (g/100 ml of solution). Since the density of chlorine solutions is higher than that of water, the percent weight measure for a given solution is lower than the percent volume measure.

This is true. But, I am just interested to know whether there can be any relation between these two values. I find that permanganate value is very high during rainy seasons because of high turbidity in water but at the same time chlorine demand is low while at the time of ammonical pollution in water with low turbidity permanganate value is low and chlorine demand is very high. It seems that both chemicals reacts in different ways with different types of contamination. Please comment

The magnitude of the permanganate value obtained depends on the suspended solids present in the water and this also depends on the pollution load. Permanganate value therefore provides information about how much suspended solids are present in the water sample. Generally high permanganate values recorded are typical signs of a polluted water. This is highly possible during rainy season. Chlorine (as hypochlorous acid) reacts readily with organic matter containing unsaturated bonds, phenolic groups and nitrogen groups, giving rise to taste- and odour - producing compounds and trihalomethanes (THMs). Hence, waters with high turbidity from organic sources may give rise to a substantial chlorine demand. Data obtained to establish chlorine demand data for use in understanding the effects of water source changes, blending operations and seasonal weather variations. The plan would include:

a) Source water description, sample location, time of year, specific or unusual

weather events.

b) Additional complementary tests to be run, such as TOC, turbidity or UV-254, in addition to the standard temperature, pH, chlorine dose rate and contact time.

In surface waters, chlorine demand has a positive correlation with both turbidity and total organic carbon levels. If the water quality of a given source varies (during wet & dry season), the chlorine demand must be reevaluated from time to time. Once the water has been disinfected, recontamination must be carefully prevented.

Before starting the analysis process, one must determine:

a) The magnitude of the chlorine demand present in the water to be tested.

b) Which chlorine method to use to determine chlorine residual.

In evaluating a new water source one should perform a screening test to determine an approximate chlorine demand level before performing a full chlorine demand test series.

Dear Jeremiah Masime, Thanks for comments. You have really a deep knowledge of the subject. Actually, we do chlorination in raw water (surface/river water) at water works in Delhi, India. Simultaneously, we perform permanganate value test as well. I do not understand what is the utility of testing water for permanganate value ? We test water for chlorine demand here, for chlorination.

The chlorine demand and permanganate number are both estimates of the oxidant reactivity (or demand) of water so you are correct in expecting some correlation.

There are two differences in the properties of the oxidants (chlorine versus permanganate):

1) Permanganate is a slightly stronger oxidant than chlorine (at the pH the tests are performed) so it con oxidize more organic matter in a sample.

2) Permanganate doesn’t oxidise ammonia while ammonia reacts very readily with chlorine to form chloramines or follow the breakpoint reaction to give free nitrogen (N2).

These properties explain your findings that water samples in the rainy season which are rich in plant derived particles and humic acids type organic matter has a high consumption of permanganate and relative low chlorine demand while in your dry season ammonia is higher and organic matter concentration lower you tend to have high chlorine demand and low permanganate numbers.

You can confirm this with ammonia and/or Kjeldahl nitrogen concentrations in your water samples over the year.

Dear Henrik Andersen, Thank you for comment. Really, you have a close knowledge of the subject. Actually, I want to establish a co-relation between these two values. But, going through your comments on the subject, I do not assume that there could be some relation between these two. So, there can not bee any relation between these two values as both of these (potassium permanganate and chlorine) reacts in different ways.

So, I think I should drop this idea of co-relating these two values. I do not find why do we test this parameter in our organization where only chlorine is applied for disinfection purpose.

Would you please comment further.

The permanganate Value is used in determining the general quality of Final Effluents in sewage. It also enables the effluent to be classified as to its acceptability for discharge. The Palintest Permanganate test is a simplified version of the standard Oxygen Absorbed (AO) test for indicating the general quality of final effluents .

Chlorine is added to the wastewater to satisfy all chemical demands. When these initial chemical demands have been satisfied, chlorine will react with substances such as ammonia to produce chloramines and other substances which, although not as effective as chlorine, have disinfecting capability. This produces a combined residual that can be measured using residual chlorine test methods. If additional chlorine is added, free residual chlorine can be produced. Due to the chemicals typically found in wastewater, chlorine residuals are normally combined rather than free residuals. Control of the disinfection process is usually based on maintaining total residual chlorine of at least 1.0 mg/L for a contact time of at least 30 minutes at design flow.

Certain factors affect the disinfection process. These include residual level, contact time, and/or effluent quality. Failure to maintain the desired residual levels for the required contact time will result in lower efficiency and increased probability that disease organisms will be discharged.

Sorry i did not answer you on time, thank you for your contibution

The permanganate number is a parameter intended to measure the total dissolved organic matter in the water sample. It should be possible to get the result the same day the sample is taken.

The chlorine consumption takes 2-7 days (depending on test protocol) to determine and this is one of the reasons to keep performing the permanganate analysis as one need to detect changes in water quality fast and adapt the water treatment including chlorine dosing.

I think there should generally be a correlation a correlation between permanganate number and chlorine consumption as they are generally both measuring oxidant demand. It isn’t a theoretical value but a correlation that needs to be derived from comparing analysis results over longer periods as the correlation will depend on the quality of the organic matter in the water. The correlation may be seasonal as the organic contamination can change between dry and extended rainy periods and with algae blooms in the source water. As I read your paper on breakpoint chlorination your raw water contains considerable ammonia and therefore you might consider this is your correlation:

Chlorine demand = (chlorine for breakpoint chlorination of ammonia) + factor x (permanganate number)

Please kindly go through this document by EPA it may give a clue;

"Despite the high degree of permanganate consumption, the reaction of Permanganate appears to have relatively little effect on chlorine demands. For example, consumption of 6 mg/L of permanganate resulted in a chlorine demand reduction of approximately 1 mg/L. This observation suggests that permanganate reacts with water impurities in a different manner, or at different sites, than chlorine. One other possible explanation is that permanganate oxidizes certain organic substances, thereby eliminating their chlorine demand and only partially oxidizing other organic substances making them more reactive to chlorine"

http://www.epa.gov/ogwdw/mdbp/pdf/alter/chapt_5.pdf

Please also look at "Development of Mathematical Model for Determining the Quantity of Chlorine Required for Water Treatment" from; https://www.academia.edu/5143203/Development_of_Mathematical_Model_for_Determining_the_Quantity_of_Chlorine_Required_for_Water_Treatment

You may come up will a model for comparing the two using Pearson Correlation both Permanganate Value and Chlorine Demand

Thanks Dr. Jeremiah Masime, for your valuable comments. In mathematical model paper I could not understand value of B?

Can you please make me understand how to put this value ?

Regards

Lokesh Kumar

B represents Coliform, The most common fecal coliform is E coli :-

Coliforms are a broad class of bacteria found in our environment, including the feces of man and other warm-blooded animals. The presence of coliform bacteria in drinking water may indicate a possible presence of harmful, disease-causing organisms. Drinking water must be free of disease-causing organisms called pathogens. Pathogens can be viruses, protozoa or bacteria. Waterborne pathogens cause diseases such as hepatitis, giardiasis, and dysentery. Coliform bacteria are used as water quality indicators for two main reasons:

a) Coliforms may be associated with the sources of pathogens contaminating water.

b) The analysis of drinking water for coliforms is relatively simple, economical and efficient.

Contact time is just as important as the chlorine residual in determining the efficiency of chlorination. Contact time is the amount of time which the chlorine has to react with the microorganisms in the water, which will equal the time between the moment when chlorine is added to the water and the moment when that water is used by the customer. The longer the contact time, the more efficient the disinfection process is. When using chlorine for disinfection a minimum contact time of 30 minutes is required for adequate disinfection.

The CT value is used as a measurement of the degree of pathogen inactivation due to chlorination. The CT value is calculated as follows:

CT = (Chlorine residual, mg/L) (Contact time, minutes)

Chlorine demand has been shown to be a key parameter in disinfection process design and in the formation of THMs in water supply systems. The presence of E.coli in drinking water indicates a failure of the disinfection process while the presence of excessive THMs reflects the reaction between the added chlorine and natural organic matter (NOM) in the treated water. It is therefore opportune to review chlorination practice both in relation to its efficacy in providing primary disinfection and its role in the generation of THMs.

The presence of organic and inorganic matter promotes the microbial growth. The organic matter in water might cause color, odor, taste as well as microbial changes during storage of treated water. It might consume additional chlorine in the water treatment plant and can act as a precursor of by products during the disinfection process.

The action of bacteria on organic matter found in polluted water is to convert the organic matter into simple organic salts. During this process, the dissolved oxygen in the water is consumed by the bacteria. This consequent reduction in the level of Dissolved Oxygen is harmful to the aquatic life and may result in the rapid death of fish. The standard test for organic pollution in water is the Biochemical Oxygen Demand (BOD) and the uptake of oxygen is measured over a 5 day period. Where a more rapid assessment is required, the 4 hour permanganate value test is recommended. Permanganate value is a measure of the amount of oxygen obtainable from potassium permanganate needed for the oxidization of easily oxidizable inorganic and organic pollutants present in wastewater samples.

CHLORINE DISINFECTS WATER BY REACTING WITH THE BACTERIA AND THE EXCESS ORGANIC MATTER, PERMANGANATE OXIDIZES THESE.

I believe this is why their concentrations are directly proportional.

https://www.ncbi.nlm.nih.gov/books/NBK234590/