STRUCTURE

• Introduction – Define Biological Oxygen Demand (15 words)                     
• Body – Explain importance of Biological Oxygen Demand (120 words)
• Conclusion – Mention a short conclusion  (15 words)

ANSWER

Biological Oxygen Demand is defined as the amount of dissolved oxygen required by aerobic microorganisms to breakdown the organic materials in a sample of water at a specific temperature & timeframe. In simpler words, The amount of oxygen needed by biological organisms such as bacteria in a given water sample for a breakdown of organic matter by oxidation process is called the Biochemical Oxygen Demand.

SIGNIFICANCE

• Measures the amount of oxygen consumed by microorganisms for the process of decomposition of the organic matters in the water bodies.
• It indicates the amount of organic pollution present in an aquatic ecosystem.
• Measures the chemical oxidation (COD) of inorganic matter.
• Used in sewage treatment or wastewater treatment to destroy and decay organic wastes through the aerobic organisms.
• Determines the amount of organic matter present in soils, sewages, sediment, garbage, sludge, etc.
• Determines the rate of respiration in living beings.
• Medicinal & pharmaceutical industries to test the oxygen consumption of cell cultures.
• Provides an index to assess the effect discharged wastewater will have on the receiving environment.
• The higher the BOD value, the greater the amount of organic matter or “food” available for oxygen consuming bacteria.
• If the rate of DO consumption by bacteria exceeds the supply of DO from aquatic plants, algae photosynthesis or diffusing from air, unfavourable conditions occur.
• Depletion of DO causes stress on aquatic organisms, making the environment unsuitable for life. Further, dramatic depletion can lead to hypoxia or anoxic environments.