Date: March 08, 2015

Ganges water pollution BOD


Meaning of BOD-

Biochemical oxygen demand (BOD) is the amount of the quantity of oxygen needed by aerobic biological organisms (e.g., aerobic bacteria) in a body of water to break down organic material.The BOD value is most commonly expressed in milligrams of oxygen consumed per litre of sample water during 5 days of incubation at 20 °C. It is often used as a robust surrogate of the degree of organic pollution of water. 


Urban runoff carries pet wastes from streets and sidewalks; nutrients from lawn fertilizers; leaves, grass clippings, and paper from residential areas, which increase oxygen demand.Oxygen consumed in the decomposition process robs other aquatic organisms of the oxygen they need to live. Organisms that are more tolerant of lower dissolved oxygen levels may replace a diversity of natural water systems contain bacteria, which need oxygen (aerobic) to survive.Most of them feed on dead algae and other dead organisms and are part of the decomposition cycle. Algae and other producers in the water take up inorganic nutrients and use them in the process of building up their organic tissues.

Reasons for High level of Biochemical oxygen demand in Ganges River-

Ganges river’s Biochemical oxygen demand is high because of water pollution and other reasons. mechanism is explained above. Now we will see the reasons for high value of BOD.The Ganges river basin is one of the most fertile and densely populated regions in the world. Pollution – Human waste, Industrial waste and religious practices etc.According to experts, The main problem with Ganga is not pollution – it’s that both the flow of the river and the quantity of water have gone down. This has led to siltation and the depth of the river has decreased.Encroachment along the riverbed has constricted the river. This has reduced the river’s self-purifying capacity.Poor management, lack of political will, corruption and lack of scientific understanding of river problems also among the various reasons for Ganges river pollution which lead to high BOD.

Expcted question for mains-

Define “BIOCHEMICAL OXYGEN DEMAND”? discuss factors affecting it and why Ganga river have high and increasing BOD? [200 WORDS]