Chemical Oxygen Demand ( B.o )

3515 Words Nov 12th, 2014 15 Pages
31. Biological Oxygen Demand ( B.O.D)
Introduction:
Biochemical Oxygen Demand (B.O.D.) is the most important parameter to determine the level of pollution in lakes and streams, their self-purification capacities, assess the biodegradable organic load of the wastewaters for designing wastewater management or treatment plants and thereafter to evaluate their efficiency or finding out the assimilative capacity of a water body. B.O.D. is an empirical standardized laboratory test defined as the amount of oxygen required for the aerobic decomposition of the organic matter by micro-organisms into stable inorganic forms at a given controlled condition of time and temperature in water. The quantity of oxygen required for above oxidation processes is the measure of the test. The test is applied for all type of water samples either being the fresh water samples (rivers, lakes), marine water (estuaries, coastal water) or wastewater (domestic, industrial).Natural sources of organic matter include plant decay and leaf fall.

Physical, chemical, and biological processes that affect dissolved oxygen concentrations in estuaries. (Redrawn from USEPA, 1998.)
However, plant growth and decay may be unnaturally accelerated when nutrients and sunlight are overly abundant due to human influence. Urban and agricultural runoff carries nutrients from fertilizers, pesticides, leaves, grass clippings, paper, faecal and sewage contamination from residential areas which increase…
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