1.2 Disinfection of the Biofilter

The suspension turning blue indicates the presence of chlorine. But there is a more efficient and accurate way to detect hypochlorite...

1.2.2 Detection and Quantification of Sodium Hypochlorite

1.2.2.b Detection of Hypochlorite in Water - method 2

If we do not want to make the colour reagent each time we need it, we should follow a precise protocol. The reagent that we will obtain following this protocol, can be stored in the refrigerator and used as many times as we like.

The colour reagent is obtained as follows:

Colour reaction:

• make in two separate bottles, a KI and a starch solution of 3 g in 100 ml deionised water
• heat the starch solution until it becomes clear
• dissolve the KI in the mean time
• stock the two labelled bottles in the refrigerator
• to check the presence of chlorine, put a few drops of each solution in a small sample

Video 1: Preparation of the reagent; chlorine present (QuickTime Movie; 14.1MB)
Video 1: Preparation of the reagent; chlorine present (Real Player movie)

Video 2: Chlorine not present (QuickTime Movie; 1.64MB)
Video 2: Chlorine not present (Real Player movie)

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