Water Treatment - Freshwater treatment

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  • Water Treatment - Freshwater treatment
    • 1).Screens
      • metals grills or meshes are used to remove floating vegetation, plastic and paper that would clog later proccesses
    • 2). Sedimentation
      • the water is allowed static to enable suspended solids such as silt to settle
    • 3).Aeration
      • 1) bubbles of air or water sprays used to aeroate water and ensure a high dissolved oxygen content
      • 2) water sources that are anaerobic may contain hydrogen sulfide from decay of organic matter making water smell bad
      • 3) some dissolved metals that are toxic or give water bad taste removed by aerations as become insoluble
    • 4)Flocculation/ coagulationand claraification
      • 1) clay particles don't settle out in sedimentation lagoons because electrostatic charges on surface cause them to repel each other
      • 2) mixed quickly with water and passed into clarifer tank where particles settle out
    • 5). Filtration
      • filters such as sand filters used to remove any remaining solids and bacteria
    • 6). Activated carbon filters
      • particles of activated carbon are used to remove organic chemicals e.g. pesticides and substances that have bad taste
    • 7). Sterilisation
      • 1) addition of chlorine, ozone or exposure to UV light used to sterilise water/kill pathogens
      • 2) chlorine is most common methods used, but if source is peaty will contain organic matter which would react with chlorine forming harmful toxins so ozone used to break down pesticides
    • 8). Fluoridation
      • fluorides added to water in some areas to improve dental health of people that drink the water


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