States of Matter and Mixtures: Water Treatment

Understanding water treatment involves mastering the three key processes: sedimentation, filtration, and chlorination.
Sedimentation is an initial step where heavy particles are allowed to fall to the bottom of a reservoir. It’s essential for removing large impurities.
Filtration is the next stage, where the water then passes through a philtre bed to remove smaller impurities.
Chlorination is a crucial final step which kills harmful bacteria and other microorganisms to make the water safe for drinking.
Ozone and ultraviolet light are other methods used to kill bacteria in water.
Fluorine may be added to the water to reduce tooth decay in populations, although this is somewhat controversial.
Some substances can dissolve in water to form a solution, such as salts, which makes treating water especially important.
Filtration methods can vary, from using sand and gravel to more modern approaches using membranes.
Hard water, which contains dissolved magnesium or calcium ions, creates problems with lathering soap and the formation of limescale.
Water can be softened by methods such as using washing soda (sodium carbonate), which reacts with the calcium or magnesium ions to form a precipitate.
Ion exchange resins are another way to soften water; the resins are small plastic beads coated with sodium ions, which will swap with any magnesium or calcium ions that pass by.
Understanding these principles of water treatment is key, as clean water is essential for health and hygiene.