Offline Storage tank and BOD calculations

Quill7567 · Oct 29, 2023

Hi everyone,
I am trying to design an offline storage tank for a problem. I have a 24-hour group of data that includes hourly average flow rate, hourly BOD concentration, and time period of course. I need to calculate the sideline storage tank volume for this, as well as the adjusted BOD mass loading. Since this is for a problem, I am not looking for any solutions, however, I am asking for someone to point me to a document that describes, in preferably few words, how to do this and what is important.

The biggest hangup for me is how to calculate BOD, as well as how much flow is entering/residing in the tank at a time. I did a similar problem for inline Storage in Excel, the file is attached.

If anyone could give me pointers or suggestions, I would greatly appreciate it. WWT is not my forte and this doesn't jive with me, so I would really appreciate help.
Thank you!

zelgar · Oct 30, 2023

If I'm not mistaken, you can easily calculate BOD concentrations by first calculating the mg of BOD in the liquid by multiplying column D & E. Sum up the mg of BOD and divide by total volume of liquid in the tank.

For example if you had a tank receiving 100 l per hour, but the BOD concentrations were 100, 200,500, 400, 100 mg/l. The formula would be summation of flow rate x BOD concentration / summation of flow rate (e.g., for the last period = [(100 l)(100 mg/l) + (100 l)(200 mg/l) + (100 l)(500 mg/l) + (100 l)(400 mg/l) + (100 l)(100 mg/l)]/(5 * 100 l)
For each time period in the above the BOD concentration would end up being the following (in mg/l): 100, 150, 266.7, 300, 260.

This is assuming you're getting total mixing, which is what you typically assume in homework.

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Offline Storage tank and BOD calculations

Quill7567

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zelgar

Civil/Environmental

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