Question

What is B.O.D?
A) The amount of \[{{O}_{2}}\] utilized by organisms in water
B) The amount of \[{{O}_{2}}\] Utilized by microorganisms for decomposition.
C) The total amount of \[{{O}_{2}}\] present in water.
D) All of the above.

Answer 1

Hint: B.O.D stands for Biochemical oxygen demand. Biochemical oxygen demand (BOD) is defined as the amount of oxygen used by bacteria and other microorganisms during the process of decomposition of organic matter under aerobic (oxygen is present) conditions at a particular temperature and in specific time periods.

Complete Answer:
- Biochemical oxygen demand (BOD), the amount of oxygen consumed by microorganisms for degradation of organic matter in the water.
- The oxygen in the dissolved form in water.
- The concentration of the organic matter in water is increasing and the BOD demand also increases.
- When, BOD demand increases means lower the amount of Oxygen in water for other animals present in water.
- The value of BOD is expressed in milligrams of oxygen consumed per liter of sample during $5$ days of incubation at \[20~{}^\circ C.\]

The rate of oxygen that is consumed by microorganisms is depends on various factors:
1) Temperature
2) pH of the water
3) Type of bacteria present
4) Type of organic and inorganic material

The amount of \[{{O}_{2}}\] Utilized by microorganisms for decomposition. Hence Option ‘B’ is the correct answer.

Additional information:
Test that is used for analysis the dissolved oxygen:
1) Dilution method
2) Manometric method
3) Winkler’s test
4) Polarographic test
5) Fluorescent test

Note:
- If the value of BOD is increased it means the level of oxygen in the water is decreased.
- The manometric method only used for determination of oxygen consumption by carbonaceous oxidation.