What is biochemical oxygen demand (BOD) test? At what stage of Sewage treatment this test is performed BOD level of the samples of water labelled as A, B and Care 30 mg/ L, 10mg Land 500 mg/L. respectively. Which sample of water is most polluted'
Answers
Answer:
Biochemical oxygen demand or biological oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms to break down organic materials present in a given water sample at certain temperature over a specific time period. When BOD levels are high, dissolved oxygen levels decrease because the oxygen that is available in the water is consumed by the bacteria. Hence, the higher the BOD higher the water is polluted.
The BOD value of sample A is 20 mg/L, which is the secondary effluent discharged from a sewage treatment plant.
The BOD value of sample B is 8 mg/L, which is the river water and it is least polluted.
The BOD value of sample C is 400 mg/L, which is untreated sewage water and it is highly polluted water.
Explanation: