Question

Measurement of the rate of oxygen utilization by a unit volume of water over a period of time is to measure
(A) Fermentation
(B) Bio gas generation
(C) Bio synthetic pathway
(D) Biological oxygen demand

Answer 1

Measurement of the rate of oxygen utilization by a unit volume of water over a period of time is used to measure a quantity that tells us the amount of organic matter present in that water. The higher the value of the organic matter, the higher will be the value of this quantity.

Complete answer:
Measurement of the rate of oxygen utilization by a unit volume of water over a period of time is to measure Biological Oxygen Demand (BOD). BOD is the amount of oxygen utilized by bacteria to decompose or break down the organic matter present in a volume of water. Thus, the higher the value of the organic matter, the more oxygen will be consumed by bacteria for decomposition and therefore, higher will be the value of BOD. If a water body has a very high value of BOD, it means that it is highly polluted by organic matter. BOD is used in sewage treatment plants to check the purity of water.

Additional Information:

Let us look in detail at the process of sewage treatment. It consists of the following steps:

Primary treatment: In this process, filtration and sedimentation are used to remove physical particles that are large and small in size. Through the process of sequential filtration, floating debris is removed. And by the process of sedimentation, soil and small pebbles are removed.
Secondary treatment: It is also known as biological treatment as useful aerobic microbes are used to remove the organic matter dissolved in the water. When this treatment is started, the BOD of water will be very high, but as bacteria break down all organic matter there is a decrease in the value of BOD. The water is said to be pure when the value of BOD is minimum.

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Therefore, the correct option is option (D) ‘Biological oxygen demand’.

Note:

-The Ganga Action Plan and Yamuna Action Plan have been started by the Ministry of Environment to prevent pollution of these major rivers by sewage water.

-According to this plant, a large number of sewage treatment plants have been proposed to be set up along the rivers.

- High BOD results in hypoxia of that water body.

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