Household water treatment using commercial products
One example you may be familiar with is Wuha Agar, a commercial product available in Ethiopia for household water treatment. It is a chlorine-based solution used for disinfection, as described above. There are several others.
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.
Aquatabs is the brand name of a solid form of sodium dichloroisocyanurate (NaDCC), a disinfectant. The tablets (Figure 10.11), which have to be imported, are easier than bleach to store, handle and transport. One tablet contains 67 mg of NaDCC and can treat 20 litres of clear water. The tablet has to be dissolved in the water by vigorous mixing, and a contact time of 30 minutes is necessary. If the water is turbid, two tablets will be needed.
P&G Purifier of water
P&G Purifier of Water is the brand name of a combined coagulant, flocculant and disinfectant product produced by Procter & Gamble (Figure 10.12), which is imported into Ethiopia. The coagulant/flocculant is ferrous sulphate and the disinfectant is calcium hypochlorite. It can be used to treat raw source waters with a wide range of turbidity and pathogen load. This water treatment chemical allows flocculation to take place and helps to remove Giardia and Cryptosporidium cysts that are resistant to chlorine disinfection. (A cyst is a dormant stage in the life cycle of some protozoa and bacteria that is resistant to adverse environmental conditions and therefore difficult to destroy.) P&G Purifier of Water comes in sachets and one sachet is needed to treat 10 litres of water.
The procedure for using P&G Purifier of Water is illustrated in Figure 10.13.