Question

Measuring 'Biochemical Oxygen Demand' (BOD) is a method used for

• A. Estimating the amount of organic matter in sewage water.
• B. Measuring the activity of Saccharomyces cervisae in producing curd on a commercial scale.
• C. Working out the efficiency of RBCs, about their capacity to carry oxygen.
• D. Working out the efficiency of oil driven automobile engines.

Answer 1

The correct option is A Estimating the amount of organic matter in sewage water.

Biochemical oxygen demand (BOD) is the amount of oxygen, expressed in mg/L or parts per million (ppm), that bacteria take from water, when they oxidize organic matter.

Bacteria in water live and multiply when organic matter is available for food and oxygen is available for oxidation. About one-third of the food bacteria consumed becomes the solid organic cell material of the organisms. The other two-thirds is oxidized to carbon dioxide and water by the biochemical action of the bacteria on the oxygen dissolved in the water. Micro-organisms involved in biodegradation of organic matter in the receiving water body consume a lot of oxygen, and as a result there is a sharp decline in dissolved oxygen downstream from the point of sewage discharge. This causes mortality of fish and other aquatic creatures.