Control of water pollution
Sewage treatment
Water pollution can be controlled by sewage treatment includes the following steps:
- 1. Sedimentation
- 2. Dilution and
- 3. Storage
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Sedimentation
When sewage is allowed to stand, the suspended particles stele at the bottom. So by sedimentation the suspended particles are removed from sewage
Dilution
The sewage can be diluted with water. This increases the O₂ contents and reduces BOD and CO2
Storage
The diluted sewage is stored in a pond. This facilitates the growth of micro organisms. This renders further oxidation of sewage.
Waste Stabilization Pond or Oxidation Pond
The National Environmental Engineering Research Institute (NEERI) at Nagpur has devised a very economical method for the treatment of industrial and domestic effluents. Domestic and industrial wastes are stored in a dilute condition in shallow ponds called Waste stabilization pond or oxidation ponds. After a few days micro-organisms and algae flourish. The micro-organisms decompose the organic wastes by oxidation and the water is purified. This water is rich in nitrogen, phosphorus, potassium and other nutrients. This water can be used for fish culture, agriculture, etc.
Recycling
- Pollution can be prevented to a certain extent by reutilizing the wastes. This is called recycling. E.g. The dung of cows and buffaloes can be used for the production of gobar gas. b. Sewage can be used for irrigation and fish culture after treatment in oxidation pond.
- Certain pollutants from industrial effluents can be removed by filtration and selective absorption.
- Excessive use of pesticides and herbicides should be avoided. At the Government level, legislations should be framed to control water pollution.