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Breakpoint chlorination

How to reach breakpoint chlorination? How to test it in drinking water ? What are the methods to test ,standards to follow and manuals to use at labs for doses of feeding chlorine to raw water ?

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Ban. You can find a brief explanation of the theory behind breakpoint chlorination here

This description is framed in terms of superchlorination in fresh produce production but the principle is the same.

In terms of testing there are a number of options. DPD chemistry as developed by Dr Palin in the 1950s is the defacto standard approach but there are other alternatives. Let me know if you want more information.

tomlendrem@Palintest gravatar imagetomlendrem@Palintest ( 2016-03-31 10:21:27 +0000 )edit

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Basically, you need to add chlorine until the point where you can measure a free chlorine residual.

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Thank you but how to test it ? I know i keep adding chlorine till i reach breakpoint chlorination but how much i add ,the standards ?

Ban Qasim gravatar imageBan Qasim ( 2016-02-05 13:38:07 +0000 )edit

Hi, Typically, free residual chlorine is measured using the colorimetric DPD method. There are several types of instruments to do so from digital colorimeters to visual "pooltester" type techniques. Just make sure you are using the right reagent as there are DPD reagents for free and for total residual chlorine measurements (as mentioned, you would be interested in the free portion). As for standards, it really depends on why you are wanting to do breakpoint chlorination. Assuming it is for drinking water purposes, please refer to World Health Organization, Sphere Project and/or CDC recommendations. Hope this helps. Caetano

Caetano Dorea gravatar imageCaetano Dorea ( 2016-02-05 14:07:14 +0000 )edit

Thank you again . There is a hach dr 2800 to measure free and total chlorine ,but how about ammonia it cause the break point chlorination how to measure it in drinking water and also PH affect and temperature . I am doing the experiment on raw water in Rural area it is for 3 Types of water ,rain water,ground water and high lands water ,also there are Standards by EPA ,WHO and APHA ,i want to do break point chlorination to enhance the disinfection in drinking water chlorination and also to control the dose of chlorine that added to drinking water ,is Hach a good to use for this purpose ?

Ban Qasim gravatar imageBan Qasim ( 2016-02-05 14:42:19 +0000 )edit

Ban The Hach meter and many others work in the same way and that is that when chlorine reacts with ammonia it initially forms 'combined chlorine' compounds such monochloramine. As more chlorine is added these are destroyed which is the breakpoint. After this the chlorine residual measured is the free chlorine residual. So if you use the tester with reagents for free chlorine you will only find this once you have passed the breakpoint.

Using total chlorine reagents will show the total of free and combined residuals and the difference between this value and the free reading is the combined chlorine. This is sometimes used where ammonia is added after free chlorine disinfection because whilst the chloramines are not powerful disinfectants they are long lasting and so after free chlorine rapid disinfection creating chloramines can protect water in long distribution systems. The Hach colourimeter is widely used and I would recommend it as long as spares standards and reagents are readily available

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2016-02-04 08:20:47 +0000
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