Under the standard comparison of typical samples used in this UGC NET…
2024
Under the standard comparison of typical samples used in this UGC NET question, which of the following generally has the highest biochemical oxygen demand (BOD)?
Answer: D. Municipal sewage effluent — ConceptBiochemical oxygen demand (BOD) is the dissolved oxygen consumed by microorganisms while they decompose biodegradable organic matter under specified…
- A.
Potable water
- B.
Unpolluted surface water
- C.
Contaminated surface water
- D.
Municipal sewage effluent
Show answer & explanation
Correct answer: D
Concept
Biochemical oxygen demand (BOD) is the dissolved oxygen consumed by microorganisms while they decompose biodegradable organic matter under specified test conditions.
A larger biodegradable organic load generally produces a larger BOD because microbial decomposition requires more oxygen.
Application
Potable water is treated to keep biodegradable organic matter at a low level.
Unpolluted surface water normally has a comparatively small human-derived organic load.
Contaminated surface water can have elevated BOD, but its value varies with the type and amount of contamination.
Municipal sewage effluent carries a substantial biodegradable domestic organic load and therefore typically exerts the greatest oxygen demand among the listed waters.
Cross-check
Ranking the choices by expected biodegradable organic load places municipal sewage effluent above contaminated surface water, unpolluted surface water, and potable water.
Therefore, municipal sewage effluent has the highest BOD among the given options.