Wastewater metrics — In environmental engineering and bioprocessing, BOD stands for what?

Introduction:
BOD is one of the most widely used measures of water and wastewater quality. It quantifies the amount of dissolved oxygen that microorganisms will consume while stabilizing biodegradable organic matter under specified conditions (often 5 days at 20 °C, called BOD5).

Given Data / Assumptions:

• Standard lab test conditions (BOD5).
• Sample contains biodegradable organics and active microbes or seed.
• Oxygen uptake reflects biochemical oxidation, not just chemical reactions alone.

Concept / Approach:
“Biochemical” emphasizes the role of microbial metabolism in oxygen consumption. BOD correlates with the organic load requiring treatment and is a key design parameter for secondary treatment units like activated sludge systems.

Step-by-Step Solution:
Recognize the acronym components: Bio + chemical + oxygen + demand.Link to test method: measure DO decline over time due to microbial action.Select the correct expansion: Biochemical oxygen demand.

Verification / Alternative check:
BOD results are often compared with COD (chemical oxygen demand); BOD is typically lower because it excludes non-biodegradable oxidation.

Why Other Options Are Wrong:

• “British” expansions are incorrect and nonstandard.
• “Biological oxygen depletion” is close in spirit but not the accepted term.

Common Pitfalls:
Confusing BOD with COD; overlooking nitrification (which can increase BOD unless inhibited or corrected).

Final Answer:
Biochemical oxygen demand