Working for the local wastewater treatment plant, you are asked by the labtechnician to help her set up BOD5 tests. The issue here is what dilution to use to get the BOD5 test to give an acceptable result. Of course, you do not know the actual BOD5 value, but you are able to determine from past tests that the total ultimate BOD (NBOD + L0) of the wastewater is546 mg/L and the organic Nitrogen (TKN) concentration of the wastewater is 32 mg N/L. You also know that the first order rate constant for the BOD test is 0.25 day-1. When you ask, the technician tells you that the normal DO concentration at the start of the test is 8.3 mg/L.Based on all this information, tell the lab technician which of the following wastewater sample volumes added to a standard BOD test bottle (300 mL) is going to produce an acceptable final result: 1 mL/3 mL/9 mL/30 mL/90 mL NOTE: Acceptable BOD test should comply with the two essential criteria: DOfinal ≥ 2 mg/L and DOinitial – DOfinal ≥ 2 mg/L.

Working for the local wastewater treatment plant, you are asked by the lab
technician to help her set up BOD₅ tests. The issue here is what dilution to use to get the BOD₅ test to give an acceptable result. Of course, you do not know the actual BOD₅ value, but you are able to determine from past tests that the total ultimate BOD (NBOD + L₀) of the wastewater is
546 mg/L and the organic Nitrogen (TKN) concentration of the wastewater is 32 mg N/L. You also know that the first order rate constant for the BOD test is 0.25 day-1. When you ask, the technician tells you that the normal DO concentration at the start of the test is 8.3 mg/L.
Based on all this information, tell the lab technician which of the following wastewater sample volumes added to a standard BOD test bottle (300 mL) is going to produce an acceptable final result:

1 mL/3 mL/9 mL/30 mL/90 mL

NOTE: Acceptable BOD test should comply with the two essential criteria: DOfinal ≥ 2 mg/L and DOinitial – DOfinal ≥ 2 mg/L.