1st stage: Screening (13.09 minute)
By passing water through mesh screens, we remove sticks, water weeds and other large
foreign objects. The air takes some odours and gas from the water and allows some
dissolved metal salts to separate and to be filtered out. We add air by cascading the water
down a tower, spraying it into the air or bubbling air through it. At this stage there are still
some fine matter suspended in the water, along with colour and bacteria.