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# Fermenter Volume

6 replies to this topic
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### #1 Arminer

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Posted 12 March 2018 - 11:56 PM

We are designing a continuous fermenter which would grow bacteria with growth rate of 0.5 g/l/h . The maximum concentration we can have in the tank is 60 g/l of the bacteria in media. we need to produce at least 1100 kg/h of these bacteria. how can we calculate the volume of the bubble column reactor ?

### #2 rikakose

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Posted 13 March 2018 - 10:43 AM

you need to solve a  differential equation based on bacteria mass balance and retention time. Media flow is constant.

bacteria concentration changes with time.

### #3 Arminer

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Posted 13 March 2018 - 07:33 PM

Any sources that I can study about that ?

### #4 Saml

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Posted 13 March 2018 - 09:06 PM

60 g/l ---> means you are removing 18333 l/h (1100 kg/h divided by 0.06 kg/l)

Growth Rate: 0.5 g/l/h ----> For steady state you need to produce the same as you remove.

So you need: 1100 kg/h / 0.0005 kg/l/h. That is: 2200000 lts or 2200 m3

And 2200/18.333 gives you a retention time of 120 hours.

For a "bubble column" it looks big.

### #5 Arminer

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Posted 13 March 2018 - 11:21 PM

yeah that's how we calculated it too and yes that's what we concluded that the reactor will be too big. Just wanted to make sure we are calculating it right. I don't know why our client keep saying we are wrong and the reactor should be much smaller :/

thanks for your help

### #6 rikakose

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Posted 15 March 2018 - 07:05 AM

It is a accumulation not simply linear  increasing.

Edited by rikakose, 15 March 2018 - 07:15 AM.

### #7 rikakose

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Posted 15 March 2018 - 07:29 AM

mt(dt)=integral(0-t)(C0+S*dt)*F*dt

C0 initial concentration

S growth rate

F flow

mt bacteria mass

retention time is around 16 hours.

Edited by rikakose, 15 March 2018 - 07:51 AM.