Bioreactor pump

[Thrin]

Hi there

I am currently running an experiment looking into the degradation of some toxic waste. We are using a consortium of bacteria to break it down in continuous flow through a set of bioreactors (buckets with a matrix for a bacterial film to grow on). What I am looking for is a pump that will provide water at a continuous rate of two litres every 24 hours, can only seem to find solutions much higher or much lower than this. I am trying to find a solution using another bucket and a tap to drip into the first bioreactor, but this is proving fiddly at best and not terribly consistent.

In the spoiler is a paint diagram of the current set up, any help or ideas would be great.

Spoiler:

Other than that, anyone else have an interest in microbiology?

[Angua]

Your image isn't working for me.... Are you on forums or fora?

[Thrin]

I assume I'm on the forums, I've never tried to add an image to this forum before so I have probably done it wrong. Does this work

[Angua]

Much better. I can't really help, but I figured you'd get a faster response once you'd got the image working!

[Thrin]

Cheers, I think it is probably going to be a matter of searching gardening and aquarium websites

[KyleOwens]

I don't know how important having exactly 2L/day is to you, but if precision isn't that important to you a simple dropping funnel and an elevated reservoir might be good enough.

[Seraph]

Do you have a price range?

My solution to a problem like this would be a peristaltic pump
Expensive but precise: http://www.masterflex.com/Product/Maste ... V-77921-70

Cheaper: http://www.grainger.com/Grainger/STENNE ... Pump-4NA11

Even Cheaper: http://www.mcmaster.com/#peristaltic-me ... ps/=hgqr7a

I recommend periodically changing the tubing in the pump.

Another method would be to get a rotometer that covers the range you're looking for, and set up a fixed pressure water source (maybe just the tap?)

[Thrin]

Sorry for the late reply. I have been using peristaltic pumps before but I could not get them to go slow enough while still maintaining pressure. Going to try some much thinner piping but I will have to see if a biofilm blocks it rapidly. Thanks for your suggestions though.

[Charlie!]

Another way to do it might be to use a small valve - keep constant pressure on one side with a pump or a reservoir or something, and just find the right setting for the valve.

[mercutio_stencil]

You're looking for a flow on the order of a few mil/minute. That is pretty low, especially for a pump that has to deal with the potential for clogging. The Welco WPX-1 might work, but I'm not entirely sure. They show up on ebay sometimes.