Explain the term biochemical oxygen demand. - Leaving Cert Chemistry - Question 1 - 2018

Biochemical Oxygen Demand (BOD) refers to the quantity of dissolved oxygen (O₂) that is utilized by microorganisms to decompose organic matter in a water sample over a specified period of time. Specifically, BOD is measured over five days at a temperature of 20 °C in dark conditions to prevent photosynthesis from affecting the oxygen levels.

The process signifies the extent of biological activity in the water, providing insights into the organic pollution levels. In essence, higher BOD values indicate greater organic contamination, as more oxygen is consumed during the decomposition process, while lower values reflect cleaner water resources.