The 5-day BOD (BOD5) test is conducted at 20 deg C. The BOD5 value represents:
Choose the correct answer
Total organic matter in the sample
Oxygen consumed in 5 days at 20 deg C by biological oxidation of organic matter
The ultimate BOD (BODu)
Oxygen demand by chemical oxidation only
Correct Answer
B. Oxygen consumed in 5 days at 20 deg C by biological oxidation of organic matter
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BOD5 = BOD exerted in 5 days at 20 deg C = L0(1 - e^(-k1 x 5)), where L0 = ultimate BOD, k1 = BOD rate constant (day^-1). BOD5 is typically 60-70% of ultimate BOD for settled sewage. Higher BOD = more polluted water.
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