10.3.1 Bishan Gari Water Purifier
The Bishan Gari Water Purifier (Figure 10.10) is a combined coagulant–flocculant–disinfectant powder mixture produced in Ethiopia for water treatment. Bishan Gari comes in a 2.5-g sachet, which is used to treat 20 litres of water. The sachet contains aluminium sulphate as coagulant and a flocculant for reducing turbidity, and calcium hypochlorite as a disinfectant to kill bacteria and viruses.
The directions for using Bishan Gari powder are as follows:
- Put 20 litres of raw water into a clean bucket.
- Open the Bishan Gari sachet and add the contents to the bucket.
- Stir rapidly with a stick for 2 minutes (to disperse the chemicals) and then stir slowly for an additional 3–4 minutes (to help the solid particles come together to form larger particles or flocs).
- Wait for at least 20 minutes for the flocs to settle and the micro-organism to die. The longer you wait, the clearer the treated water will be.
- Strain the water through a thick cotton cloth into a safe water storage container, from which it can be consumed.
- Dispose of the material that settles at the bottom of the bucket by burying it.
10.3 Household water treatment using commercial products