Thermal Pollution
When the temperature of water - body or air in the atmosphere is increased or lowered, we call it thermal pollution. The temperature of water bodies regulates the aquatic life. If the temperature of oceans is lowered by even one degree, the environment becomes harmful to some corals and reef species.
Similar effect is felt if the water temperature increases. Thermal pollution occurs when the heat generated in any process is released into water bodies. Some of the causes of thermal pollution include:• Forest fires and volcanic eruptions
• Metal smelters, processing melts, petroleum refineries, paper mills, food processing units
• Chemical manufacturing plants, power plants and refrigeration units.
In all the above processes, water is used as a coolant. Water gets heated and the hot water is released into water bodies.
Thermal pollution has profound effect in aquatic system. Some of these effects are
• Reduction in dissolved oxygen thereby affecting aquatic life.
• Increase in BOD.
• Multiplication of bacteria, which in turn became food of protozoa.
The best course to remove chronic thermal pollution is to retain the heated water and effluents discharged by power plants and other industrial units in a holding section and cool them prior to their discharge in water bodies. Alternatively, the heat generated from industrial units can be used for purposes like warming the buildings in colder seasons.