Which statement about BOD and BOD5 is true?

Which statement about BOD and BOD5 is true?

• A. BOD5 measures color change due to microbial activity.
• B. Biochemical Oxygen Demand over 5 days; it provides a standardized, reproducible measure of readily biodegradable organic matter and allows comparison between samples.
• C. BOD5 measures inorganic oxygen demand.
• D. BOD5 is measured over 1 day.

Answer: (B)

BOD5 is about measuring how much oxygen microorganisms need to biologically oxidize the organic matter in wastewater over a fixed five-day period under standardized conditions. This fixed time frame, along with controlled temperature and sealed bottles, makes the result reproducible and directly comparable from one sample to another and across labs. The value reflects the amount of readily biodegradable organic material present, which is why it’s used to gauge wastewater strength and potential treatment performance. It isn’t about color change, it doesn’t measure inorganic oxygen demand, and it isn’t completed in one day, all of which is why the five-day, standardized approach is essential.

BOD5 is about measuring how much oxygen microorganisms need to biologically oxidize the organic matter in wastewater over a fixed five-day period under standardized conditions. This fixed time frame, along with controlled temperature and sealed bottles, makes the result reproducible and directly comparable from one sample to another and across labs. The value reflects the amount of readily biodegradable organic material present, which is why it’s used to gauge wastewater strength and potential treatment performance. It isn’t about color change, it doesn’t measure inorganic oxygen demand, and it isn’t completed in one day, all of which is why the five-day, standardized approach is essential.