DIY micron filters?

[Jonathan Cline]

I need many micron filters for straining large quantity of liquid (liter volumes of water-oil emulsion).  These filters are expensive from biotech suppliers and only last for some time until they clog.  100 um and 40 um.  Is there any way to DIY these?   Spinning is not really a solution and applying pressure is also not a good idea.  How are these filters made?   Does substituting a much cheaper alternative (i.e. drinking water filter or aquarium filter) yield the same accuracy?




## Jonathan Cline
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[Dakota Hamill]

Two years ago for an algae biofuel project a friend and I used some big bag filters that looked like giant socks to filter ~20L of an algae + water suspension

http://www.filterbag.com/Filter-Bags-c2/

I don't know if those are the exact brand, but we got a 100um and a smaller rated one as well, I think 25 perhaps.  

We flocculated the algae with NaOH and it all settled to the bottom of the 2L bottles, then we just poured it into those big sock filters and let gravity do the rest. It filtered probably 99% of the cells, did a great job, and was easy to collect the algae by just scraping it off in between pours. Never seemed to have any problems with clogging if you just cleaned in between runs.

For only $11-$15 I think those might be worth giving a try

[Avery louie]

You might look at a lifestraw or something.  they are for outdoorsy-types to filter contaminants out of naturally occurring water.  They may clog, but IIRC they are cheap!

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[Matt Conway]

I have a friend that has oodles of "expired" micron filters for large scale processing.  They are 40 micron, hollow fiber, thousand dollar filters. They are expired in the sense they sat on the shelf too long for use in drug manufacturing, but should be ok your means.  They were in the dumpster of a biotech company going out of business and we fished them out, and tried to sell them on ebay, but there were no takers at that time. 

I don't know the exact stats, but they look kind of like this, and take 1.5 or 1 inch sanitary fittings in and 0.5 inch sanitary fittings out. 

http://www.gelifesciences.com/aptrix/upp01077.nsf/Content/bioprocess~filtration1~ultrafiltration_hollow_fibers~lab+pilot+uf 

This is probably a scale up from what you need, but let me know. 

[Patrik D'haeseleer]

How about some high-end cotton sheets? A thread count of 400 amounts to 200x200 threads, or a pitch of 127 micron, so the gaps between threads must be much less than 100 micron.

[Giovanni Lostumbo]

I've been interested in this for a while. If 3D-printers can do it, using ultra-violet ray lithography or something, that would be really interesting.

On Sunday, April 15, 2012 12:19:42 PM UTC-4, Jonathan Cline wrote:

I need many micron filters for straining large quantity of liquid (liter volumes of water-oil emulsion).  These filters are expensive from biotech suppliers and only last for some time until they clog.  100 um and 40 um.  Is there any way to DIY these?   Spinning is not really a solution and applying pressure is also not a good idea.  How are these filters made?   Does substituting a much cheaper alternative (i.e. drinking water filter or aquarium filter) yield the same accuracy?




## Jonathan Cline

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[Cathal Garvey]

I found some domestic ceramic water filters, sometimes called "candle filters" or suchlike, on Ebay. Never used them yet because they're really only for large volumes, greater than one litre at least.

I suspect that for an oil emulsion though, you'll have to use something more expensive to avoid the oil adhering to/clogging the filter?

Jonathan Cline <jnc...@gmail.com> wrote:

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[Patrik D'haeseleer]

I was just rereading the Sprirulina growing article in the July issue of Make, and noticed they recommended screen printing fabric as a filter for gallons of spirulina culture. 40 micron openings would correspond to 325-400 mesh fabric. 100 micron pores would be 140 mesh. Here's a lookup table:

http://support.silkscreeningsupplies.com/entries/20390368-mesh-to-micron-conversions

On Sunday, April 15, 2012 9:19:42 AM UTC-7, Jonathan Cline wrote: