I am working on a project to demonstrate the production of PLA suitable for 3D printing from an agricultural feedstock using open source development. The plan is being documented on the Open Source Ecology wiki. I am a graduate student in biochemistry and I have been talking with a material scientist at another university about collaborating on the project next summer. Another post doc collaborator is building a flexible open source bioreactor and will be sharing his schematics and arduino code over the next few months. If anyone has any technical feedback or can assist with development that would be great.

The plan is to build a low cost bioreactor to grow the lactic acid bacteria Bacillus coagulans and harvest the lactic acid through membrane separation. The membrane separation would follow the scheme of ultrafiltration, stacked electrodialysis, conventional watersplitting, then polishing steps involving ion-exchange. Polymerization will take place in reactor under a vacuum/low pressure using SnCl2 and p-toluenesulfonic acid as catalysts. The details and literature reviewed are available on the wiki pages.

Feedback or development collaborators are welcome to respond here or on the wiki.

Sounds great, poli ... and like there's quite a way to go.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Hi Poli,

It sounds like one of the challenges in the membrane filtration step is preventing fouling.

Back in the 1970s I worked at a company making zonal separation centrifuges (see attached ad from 1971) and I wonder whether this technique would be helpful. It's a pretty basic mechanism and doesn't rely on any exotic materials or fabrication technology. Even more basic would be batch centrifugation in cups (like blood separation).

Running a centrifuge consumes energy but if it can run under modest vacuum the air friction -- which is the biggest loss -- drops dramatically.

Cheers,
Chuck

Thanks for the info and I included you in the year end email update I just sent. Lactic acid is a very small molecule and fairly soluble in water and separation by centrifugation would start with solvent extraction. Membranes really appear to be the most efficient route for polymerization grade lactic acid and has many other added benefits to the process, such as cell recycling, pH maintenance, and limited use of highly available basic salts. Progress in preventing membrane fouling has been made recently by using a series of membranes that serially remove contaminants, testing a variety commercially available membranes to find optimal products, and configuration for crossflow to minimize buildup. If you have any feedback on how to configure pumps or what not that would be helpful.

Hi,

what is your progress on this project? I'ld love to make my own PLA

Very cool. In a few years, we will have homebrew kits for PLA flakes thanks to work like this.