BOD 5 represents 5-day biochemical oxygen demand at temperature of:
- A0° C
- B20° CCorrect
- C30° C
- DNone of the above
Solution
Concept
Standard temperature for five day BOD test
Formula
NONE
Step-by-step solution
1. Biochemical Oxygen Demand (BOD) measures dissolved oxygen consumed by microorganisms decomposing organic matter. 2. Standard BOD testing is conducted over a standardized time period of 5 days. 3. The standard incubation temperature specified for the BOD 5 test is 20° C. Answer: B
Explanation
Biochemical oxygen demand measures the amount of dissolved oxygen consumed by microorganisms while decomposing organic material. Standard testing procedures measure this demand over an incubation period of 5 days at a controlled temperature of 20 degrees Celsius. This standard condition ensures consistent and comparable measurement across different wastewater samples.
Why the other options are wrong
A) Biological degradation is dormant at 0°C, making it an unsuitable test temperature. C) 30°C is used for 3-day BOD testing in specific regional standards, whereas standard BOD5 is specified at 20°C. D) Option B is correct as 20°C is the standard test temperature for 5-day BOD.
Shortcut
Standard BOD5 is measured over 5 days at 20° C.
Common mistake
Assuming standard BOD 5 incubation occurs at 30°C or 0°C instead of the standard 20°C reference temperature.
Correct answer: B) 20° C