Self-Destructing Microbial Robots Turn Wastewater Into Gold Mine

September 18th, 2013 by Tina Casey

Since we’ve been on something of a wastewater tear this week, let’s keep the ball rolling with a look at another form of new technology for harvesting renewable energy from the stuff. This one is from a company called Pilus Energy. The company has tweaked bacteria to come up with proprietary energy-harvesting organisms it calls BactoBots™, leading to a new generation of high efficiency microbial fuel cells.

A Next-Generation Microbial Fuel Cell

While other wastewater-to-energy systems involving organisms have exploited the digestive or fermentation pathways, Pilus Energy has focused on the metabolic pathway.

So far, Pilus has released two products, RemdiBot and GalvaniBot. We’re especially interested in GalvaniBot, which forms the heart of what the company calls a next-generation microbial fuel cell. Here’s the connection, as explained by Pilus:

Most bacteria can gain energy by transferring electrons from a low-potential substrate, such as glucose, to a high-potential electron acceptor, such as, for example, molecular oxygen, a process commonly referred to as respiration. In humans, the mitochondria represent the metabolic “furnaces” that perform the same function…Essentially, our organism possesses nearly identical energetic properties of the human mitochondrion. In fact, many scientists believe that human mitochondria have evolved from bacteria [more details here].

In addition to generating electricity, GalvaniBot reduces hundreds of organic pollutants in wastewater into high value products, namely renewable hydrogen and methane.

That helps to resolve a problem we noted earlier, which is that the energy density of wastewater is quite low compared to other renewable feedstocks. By extracting more high-value products from wastewater, the BactoBot system has the potential to be cost-effective.

The Go-Anywhere Self Destructing Robot

Pilus has come up with a couple of other interesting tweaks to the microbial fuel cell concept. It has protected its proprietary bacteria with a “key” in the form of a non-toxic additive. Without the additive, the BactoBots quickly die off or self-destruct. In addition to forestalling theft of the genetic code, the key helps to prevent the engineered bacteria from drifting into other environments.

Another aspect of the system is its scalability and portability. In addition to use at large, centralized municipal wastewater facilities, the system could prove cost-effective at residential, commercial, and industrial sites of various sizes, as well as schools and other institutions, and public facilities.





Depending on its mobility, scaled-down versions of the system could also be used at temporary camps (including temporary military bases) and construction work sites.

The system could also serve as an on-board wastewater-to-energy reclamation system on ships, which would open up a boatload of possibilities including cruise ships and military vessels. In that regard, the US Navy is already quite interested in microbial fuel cells.

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