Among other things, microalgae is a potentially valuable source of biofuel. Unfortunately, however, growing it on a large scale can be a rather fussy process, making it less likely to be adopted commercially. Syracuse University Ph.D. candidate Bendy Estime has set out to change that, by developing a new growth medium that makes cultivation and harvesting easier.
When it comes to growing microalgae in rows of clear tubes, there are a few challenges. For one thing, some of the algae tends to cling to the inside walls of the container, blocking light from reaching the rest of the algae that's growing deeper within. For another, the liquid growth medium needs to be stirred frequently, in order to expose all of the algae clusters to the light.
Finally, when harvesting the algae, the process of separating it from the medium is time- and energy-intensive.
With these things in mind, Estime created a growth medium known as Tris-Acetate-Phosphate-Pluronic (TAPP).
To start, when the TAPP is at a temperature of 15 ºC (59 ºF) and is in a liquid state, it's seeded with microalgae cells. Its temperature is then raised by seven degrees, causing it to gel. Within that gel, the algae proceeds to grow in clusters that are 10 times larger than those that grow in a traditional medium. The fact that there are fewer, bigger clusters allows the light to reach all of them.
Come harvest-time, the TAPP's temperature is decreased back down to 15 º, causing it to revert to a liquid state. When this happens, gravity causes the clusters to settle to the bottom of the tube. The temperature is then raised again, returning the TAPP to a gelatinous state. A cap on the bottom of the container is then removed, and the settled clusters are simply scraped off of the gel.
"The industrial applications of this system are appealing," says Estime. "This system would harvest microalgae 10 times faster than traditional systems and in an energy-efficient fashion."
A paper on the research was recently published in the journal Scientific Reports.
Source: Syracuse University
