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Session18: School Students


Chairman: Dr. jack Vallentyne & Dr. T. V. RamaChandra 

Purifying Water by Natural Biological Process

Bharath H. Aithal, Devaraj, B.M., Narendra S.S. and Rishikesh Madhev Address

Water is a natural gift of nature.  Man pollutes this useful gift.  This is water pollution i.e. the contamination of water by sewage, toxic chemicals, oils or other substance.  It can affect such surface waters as river, (banks) lakes and oceans, as well as water beneath the earth surface, called ground water.


Water pollution can harm many species of plants and animals including man.  This pollution occurs when people put so much waste into water system that its natural cleansing processes cannot function properly.  Some water, such as oil, industrial acids, etc. poison aquatic plants and animals.  Other water such as phosphate detergents, chemical fertilisers etc. pollutes by supplying excess nutrients for aquatic life.  This pollution process is called as Eutrophication.  This process begins when large amounts of nutrients flow into a water system.  These nutrients stimulate excessive growth of algae.  Bacteria in the water use up large amounts of oxygen digesting the excess dead algae.  The oxygen level falls resulting in death of aquatic animals.

 Sometime water pollution occurs when there is improper separation of sewage water and pure drinking water.  If there is improper service of pure water it results in diseases such as cholera, dysentery etc.

 How can this pollution be avoided by Biological process or any process?

This problem can be solved by the biological process.

 Aim:  Purifying water by natural biological process?

 Principle: Aerobic bacteria are used to turn waste into useful or harmless substance.

 Materials: Polluted water, bacteria, test-tube, and a jar


 In a healthy water system, a cycle of natural processes turns wastes into useful or harmless substance.  This biological cycle begins when aerobic bacteria present in the air use the oxygen (O2) dissolved in water to digest wastes.  This digestion process releases nitrates, phosphate and other nutrients (chemical substance that living things need for growth). Algae and aquatic green plants absorb these nutrients.  Microscopic animals called zooplankton eat the algae and fish eat the zooplankton.  This fish may be eater by the larger fish.  These animals produce body wastes and die.  Bacteria break down dead animals and animal wastes, and this cycle begin again.


 Using aerobic bacteria present in the air the polluted water can be made useful or harmless

 T (h) anks, for Water?Sidram V Dhande
X Std,
S.B. Residential Pre University College,
Gulbarga – 585103, Karnataka, India

 “There is no greater object of wonder, no greater thing of beauty than the dynamic order and the organised complexity of life”. This was the famous saying of Ariel G Loewi and Philip. And another great scientist, Haldane says that “…The line between living and non-living is somewhere between a cell and an atom…..” and that thing is obviously water. If we carefully look over these sayings, we can easily make out that, water is the origin of life. This matrix of life is present in the storehouse earth in the form of lakes, ponds, rivers seas and oceans. And for his convenience man has built many artificial ponds, dams, reservoirs and tanks.

 We have all seen many lakes, rivers, tanks etc., but do they all ensure pure and good quality water? No. One such tank called, Jagat tank is in Gulbarga city. Located in the heart of the city, it is the refuge for the disposed sewage. Jagat tank is also getting polluted due to the washing of cattle with the tank water. Pollutants like detergents are added to the tank due to the washing of clothes on its banks. Some citizens of Gulbarga have exploited this tank to a very great extent. For example if fishing is going on one side of its bank, at the same time the toxic hostile wastes are dumped into it on its either side. And the menace plastic is no less. As a result this tank has not only become useless but has lost its scenic beauty. Usually these tanks are built to maintain a good environment and for recreation purpose. But, due to the damage caused to it, in the form of pollution, Jagat tank has become a breeding ground for pathogens.

 If this pollution goes on for some more days than, this boon will not only become a bane but will also disturb the delicate balance of the environment. So, today the immediate and urgent need is to create awareness among the people about the grievous consequences of pollution of the tanks, passing laws for the prevention of pollution of tank and their strict implementation. Taking strict actions against lawbreakers. Thus, we can save the matrix of our life.

Address: Sri Vani Educational Centre,
Basaveswaranagar, Bangalore - 560 079, Karnataka, India