Biochemical Oxygen Demand

Biochemical Oxygen Demand (BOD)

Biochemical Oxygen Demand is a chemical procedure to determine the amount of oxygen needed by aerobic biological organisms in a body of water to break down organic matter at a certain temperature over a specific period of time.

Applications of BOD Test:

  • To determine the approximate quantity of oxygen required to stabilize organic matter in water bodies and wastewater.
  • To measure the amount of biologically oxidizable organic matter in wastewater.
  • BOD values help design the biological units of wastewater treatment plants and measure the efficiency of treatment units.
  • BOD is a key parameter for stream pollution control and assessing pollution levels in water bodies.
  • BOD data are used to evaluate the self-purification capacity of receiving water bodies.

Explanation: BOD Test for Measuring Water Pollution

BOD testing estimates the oxygen demand of water bodies, as aerobic bacteria consume organic matter through oxidation, using dissolved oxygen. Organic matter on the water's surface can deplete oxygen, endangering aquatic life. By quantifying the oxygen required to degrade organics, the BOD Test assesses pollution levels.

Limitations of BOD Test:

  • High concentrations of active and acclimatized seed bacteria are required.
  • Retreatment of samples may be necessary when dealing with toxic waste.
  • Pre-treatment is necessary to reduce the impact of nitrifying bacteria, which can increase BOD values.
  • BOD only measures biodegradable organics.
  • Test results take a relatively long time to obtain.
  • The test loses stoichiometric validity after stable organic matter in solution has been utilized.