Pumping and screening involve drawing the water into the plant through a screen that traps larger solids. Flocculation disinfects raw water through the addition of chemicals such as aluminum sulphate and activated silica. Settling clarifies the water and removes the flocculents added in step 2. 4. Filtration involves passing the clarified water through a bed of sand and anthracite, from which it emerges almost ready. Chlorination disinfects the water and finally makes it safe for distribution.
Some plants also use ozone , a disinfectant that improves the taste, smell and colour of water.
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