Classification of water pollution

The signs of water pollution have been obvious to even the most casual observer. The origins of these problems could be attributed to many sources and types of pollutants. To aid in a systematic diffusion of water pollutants, they will be classified into 9 categories given below:

1)      Oxygen-demanding wastes: Dissolved oxygen has been a fundamental requirement of life for the plant and animal population in any given body of water. Their survival is dependent upon the ability of the water to maintain certain minimal concentrations of this vital substance. Fish need the highest levels, invertebrates lower levels, and bacteria the least. For a diversified warm-water biota, including game fish, the dissolved oxygen (DO) concentrations must be at least 5 mg/l 5ppm). A body of water has been classified as polluted when the DO concentration drops below the level necessary for sustaining a normal biota for that water. The primary cause of water deoxygenation has been the presence of substances collectively called oxygen-demanding wastes.

2)      Disease-causing agents: In any community it must be regarded that a certain number of individuals will get diseased and thus capable of contaminating the water with various infections agents. An indicator organism, Coliform bacteria, has been forming the basis of the indirect method commonly used. These benign organisms live in the large intestine and absorb nutrients from their surroundings. It is estimated that billions are exerted by an average person per day.

3)      Plant nutrients: Nutrients are an important limiting factor in the growth of all plants. With all other factors equal, the rate and profuseness of plant growth are proportional to the amount of nutrient available.

4)      Agricultural water pollution: It includes sediments, fertilizers, and farmanimal wastes. These pollutants can all enter waterways as runoff from agricultural lands but farm animal wastes are an especially large problem near the large feedlots on which thousands of animals are concentrated. Agricultural waste includes the pesticides that are sprayed on crops, as well as sediment, fertilizers and plant and animal debris that are carried into waterways during periods of rainfall or as runoff and during the irrigation of farmland.

5)      Solid waste pollution: Solid waste varies in composition with the socio economic status of the generating community. The following materials could be classified as solid waste;

a)      Garbage, which includes all decomposable wastes from households, as well as from food, canning, freezing and meat-processing operations.

b)      Rubbish includes all non decomposable wastes. These materials may be either combustible or non combustible.

6)      Thermal pollution:  Thermal pollution takes place because many electric-generating companies use water in the process of cooling their generators. This heated water is then released into the system from which it was drawn, causing a warming trend of the e surface waters.

7)      Shipping water pollution: It includes both human sewage and other wastes, the most important of which has been oil. There are about 15 million watercraft on navigable aters and their combined waste discharges are equivalent to a city with a population  of 2000000.

8)      Radioactive waste pollution: The major sources of radioactive wastes have been n uclear explosives, accidents at nuclear power plants, fuel-reprocessing plants, and research laboratories and hospitals that release these wastes into the atmosphere or into waste water.