6 replies to this topic

[Arminer]

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 ?   

[rikakose]

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

bacteria concentration changes with time.   

[Arminer]

Any sources that I can study about that ? 

[Saml]

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.

[Arminer]

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

[rikakose]

It is a accumulation not simply linear  increasing. 

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

[rikakose]

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.