MFC Update #4, Harvesting & Biofilms!

As I discussed in my last update, getting the algae to latch onto my electrode has been a big hurdle. Luckily, instead of 3d printing a filter apparatus, I was able to get a good amount of algae onto the carbon cloth simply through thinning the culture. This freed up space in the dense culture and allowed the spirulina already colonizing the electrode to grow further. To harvest the algae I filtered approximately a quarter of the culture through coffee filters three times. The spirulina collected on the outside while the water and nutrients went through. I was then able to add the filtered water back to my culture, and dry the harvested algae.

Because I have read so much about the use of spirulina as food, I couldn’t help but to try some of my freshly dried, homegrown algae. I bought a bag of ground spirulina last month, and I have been eating it in smoothies since then. It has a very strong taste that is both fishy and metallic, which is a taste I have been struggling to acquire. This is what I was expecting when I tasted my freshly dried spirulina, but it was very different. My algae¬†had a very mild taste with a really interesting soft/slimy texture. It was much more enjoyable than what I had bought at the store and I now understand how dried spirulina cakes are edible enough to be a staple in certain cultures.

Back to my electrode. I have a very light growth of algae on around 80% of the surface area of the cathode. Since this biofilm will control the current my fuel cell will be able to produce, I am trying to increase the cover and density of the biofilm. I think even after my harvest, the culture is too dense to allow the biofilm to expand to its full potential. To allow it to do so I plan of placing the cathode, with its attached biofilm, in a second aquarium where it can grow unhampered by other algae taking all the light/nutrients. In order to do this I will need to order another aquarium and aquarium heater in order to provide both cultures with proper growing conditions. I hope to try this approach until next Wednesday, at which point I will assemble my fuel cell regardless of how the biofilm looks in order to give myself time to troubleshoot the final product and film the process.