My BOD results show that there was no dissolved oxygen depletion. What is the reason?
No dissolved oxygen depletion in BOD
- No bacteria to deplete the oxygen.
- No food to deplete - the sample has no BOD.
- The dissolved oxygen meter is not functioning.
- Certain samples are not suitable for BOD analysis. If there are large amounts of toxic metals in the sample, COD is the only way to be certain of its oxygen demand.
- Check the sample for chlorine. Any residual chlorine will cause zero depletion. If the sample has ever been disinfected, it must be seeded. Ensure that the pH of the sample is 6.5-8.5.GGA must be seeded.
- Verify that the dissolved oxygen meter is measuring correctly in a zero-DO solution. If it measures below 0.1 mg/L then it is working correctly. If it measures above 0.1 mg/L then re-calibrate using a zero-DO solution.