PURIFICATION OF WATER

Water from streams and rivers can be purified by boiling for at least ten minutes to destroy all harmful organisms such as bacteria and the eggs and larvae of worms.

If the water contains suspended matter, it should be filtered before boiling.

Filtering can be done through filter beds or through a clean cloth. A porcelain filter removes all suspended matter and may remove bacteria as well.

Purification of water depends on the purpose for which the water is being purified. Therefore, methods of purifications are chosen with respect to water use; eg. For drinking, watering crops, cleaning clothes, etc.


THREE TYPES OF WATER PURIFICATION
The three types of water purification are:

(i) Purification of water for drinking in a local area.

(ii) Purification of water for drinking in commercial towns.

(iii) Purification of water for town water supply


PURIFICATION OF WATER FOR DRINKING IN A LOCAL AREA.

The following steps may be followed to purify water for drinking in a village

(a) Water is fetched into a container

(b) The water is boiled to kill bacteria

(c) The boiled water is allowed to settle

(d) A clean white cloth is used to Filter the water.

The filtered water is kept in a clean container.



PURIFICATION OF WATER FOR DRINKING IN COMMERCIAL TOWNS

Purification of water for drinking in
commercial towns may be done by the process of distillation. The steps are:

(a) Water is fetched and boiled in distillation plant.

(b) The plant allows the water vapour to be collected.

(c) The collected water vapour is condensed, by cooling, back into water.


PURIFICATION OF WATER FOR TOWN SUPPLY.
lmpure water may be made pure for town water supply at water works. E.g Kpong Water Worka and Weija Water Works in Ghana.


The procedure is as follows:

(a) Water is pumped from a river or a dam

(b) The water is allowed to pass over gravel to filter it.

(c) The water is allowed to settle; aided by the addition of alum. (This is called sedimentation stage).

(d) It is then exposed to air to remove odour and kill some micro-organisms.

(e) A calculated amount of calcium hydroxide is added to control the pH and partially soften the water.

(f) Chlorine is added to kill bacteria. The water is now ready for town supply.

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