7 replies to this topic

[Su Lei]

Hi all,

 

Please kindly share me how to predict the BOD result from COD result.

Currently I found factor by Dividing by COD result from BOD result of previous results but got the different result with prediction.

Please let me know the predict ways.

 

Thanks.

[TimG]

You have given no information to help determine if there is a possibility that a CoA could relate to BOD. I am assuming you mean biochemical oxygen demand? I had to calculate an estimated BOD based on amount of sugar we dumped down the drains every year for the EPA, but that was taking established parameters and calculating an estimate based on known variables. We still had to have validation from a 2 sample testing process referenced below:

BOD measurement requires taking two samples at each site. One is tested immediately for dissolved oxygen, and the second is incubated in the dark at 20 C for 5 days and then tested for the amount of dissolved oxygen remaining. The difference in oxygen levels between the first test and the second test, in milligrams per liter (mg/L), is the amount of BOD. This represents the amount of oxygen consumed by microorganisms to break down the organic matter present in the sample bottle during the incubation period. Because of the 5-day incubation, the tests should be conducted in a laboratory.  https://archive.epa....html/vms52.html

 

The group here is probably going to need more info to give you anything helpful.

[Su Lei]

Thanks for your sharing and sorry for inconvenience.

Yes, I meant BOD for Biochemical Oxygen Demand.

Currently my boss wants me to dilute for Influence Waste base on COD Results.

Firstly, we found the dilution factor by average of BOD result divided by COD results. For prediction of BOD result, must be multiply the COD result with dilution factor.

e.g. Dilution factor is 0.2 and COD result is 1355 mg/L, Predict BOD result will be 1355 * 0.2 = 271 mg/L. In this situation, I check the sample volume to analyze with this BOD range at the BOD dilution factor table.

It shows 5ml sample need to put.

But in actual analysis, the result is less than we predicted. 

Therefore, I assume our finding factor is probably wrong and I want to know the right ways to predict the BOD result base on COD result.

 

Thanks and Regards,

 

 

 

You have given no information to help determine if there is a possibility that a CoA could relate to BOD. I am assuming you mean biochemical oxygen demand? I had to calculate an estimated BOD based on amount of sugar we dumped down the drains every year for the EPA, but that was taking established parameters and calculating an estimate based on known variables. We still had to have validation from a 2 sample testing process referenced below:

BOD measurement requires taking two samples at each site. One is tested immediately for dissolved oxygen, and the second is incubated in the dark at 20 C for 5 days and then tested for the amount of dissolved oxygen remaining. The difference in oxygen levels between the first test and the second test, in milligrams per liter (mg/L), is the amount of BOD. This represents the amount of oxygen consumed by microorganisms to break down the organic matter present in the sample bottle during the incubation period. Because of the 5-day incubation, the tests should be conducted in a laboratory.  https://archive.epa....html/vms52.html

 

The group here is probably going to need more info to give you anything helpful.

[beautiophile]

What I read on the internet is that the conversion factor is an experimental value. It means you have to determine it by yourself based on several analyses.

The determination can be either

    average-experimental-BOD over average-experimental-COD

    or

    linear regression with R-square > 0.95.

The latter is easily done with a help of Excel. 

[Charles.C]

What I read on the internet is that the conversion factor is an experimental value. It means you have to determine it by yourself based on several analyses.

The determination can be either

    average-experimental-BOD over average-experimental-COD

    or

    linear regression with R-square > 0.95.

The latter is easily done with a help of Excel. 

From longish memory, it is not unusual for experiential  "factors" to be utilised for predictive purposes although as per usual, the actual data "rules".

[beautiophile]

From longish memory, it is not unusual for experiential  "factors" to be utilised for predictive purposes although as per usual, the actual data "rules".

Saying for regression techniques, they have a predictive purpose when the result comes from an extrapolation. In case of the interpolation, the purpose is called determining.

[Charles.C]

Saying for regression techniques, they have a predictive purpose when the result comes from an extrapolation. In case of the interpolation, the purpose is called determining.

I suspect they also involve not inconsiderable work.

 

I guess it depends on the level of accuracy required.

 

As I recall the typical objective for Plant waste treatment units is to enable the final output to be classified as suitable for discharge into conventional drainage systems. IMEX this necessitated using an approved Consultant/Procedure.

Edited by Charles.C, 14 October 2020 - 08:18 AM.
added

[trubertq]

I used to work on this years ago but we always had to have a lot of experimental data before we could come up with an accurate factor. 

 

alas, every system ids different because of all the different variables and therefore lots and lots of COB/BOD analyses over time to determine the average,

 

 

I am surprised and not a little disappointed that BOD is still in use, as they are the most temperamental, frustrating analysis to carry out. Invariably you'd end up with no result at the end... Even talking about them makes me cross