@khalilulmagashi
Purification of water for town supply water from rivers and lake is stored in a reservoir and then treated before before supplied to towns as pipe bone water . the treatment of those water follow some step and those steps are :- Aeration, Sedimentation, Coagulation, filtration, disinfection. P.H adjustment and distribution. After those steps the water is distributed through underground pipes and supply to towns and villages for domestic use. AERATION: This is a process of exposing the water to air and sunlight. this process helps to kill some bacteria in the water. Sedimentation: When the water is kept in the reservoir for days , the mud and the other heavy materials in the water settle down by sedimentation. Coagulation: some calculated amount of chemicals are added into the settled water, those chemicals are called coagulates. they are added form the coagulation of smaller dirt and colloidal particles . The chemicals used are; Potash alum or sodium aluminate . Filtration: The sediment and other coagulated particles are removed by passing the water through sand-beds and through layers of fine charcoal. this help to remove fine sediments and other unwanted coloring matter. Disinfection: This is a process of adding chemicals like chlorine which kills germs iodine and fluorine can also be added as supplements. P.H Adjustment: Calcium Hydroxide can be added to the water t reduce the acidity of the water.
