PORTEFEUILLE

Water treatment is fundamental in establishing a nominal quality of life. Its implementation is the first step in advancing a developing country, and it remains an ongoing area of research and progression in developed countries. Though hazardous water treatment is vital for all humans, it unfortunately remains inaccessible for many communities around the world. Wastewater treatment plants are typically the largest energy consumers in most developed cities, accounting for approximately 30-40% of the city's total energy consumption and costing over 40 billion CHF per year. This taxing energy cost severely limits the integration of water treatment plants in developing communities that lack the resources needed to meet this demand.
One approach to offsetting the energy needed to process wastewater is to extract energy that is stored in the unwanted waste. Microbial fuel cells (MFCs) offer a commercially viable basis for treating wastewater while also extracting power from waste material. In this project, we successfully engineered bacteria that are capable of producing electricity from organic waste material. We achieved this goal by applying synthetic biology techniques that allowed us to introduce foreign proteins inside the bacteria. We then optimized the performance of these bacteria to maximize power generation. Finally, we incorporated these bacteria into a MFC and demonstrated their application for producing electricity from industrial wastewater.

This project focuses on providing wastewater treatment facilities the most cost-effective and energy-efficient method for treating organic waste. In achieving this aim, this work has yielded the first demonstration of a working MFC based on bacteria that have been specifically bioengineered and optimized for this application. This technology benefits from a combination of favorable characteristics that have been explored for the first time in this project. Furthermore, we were able to identify, understand, and overcome the bottlenecks that had previously limited the use of these microbes for this application.
The project's success has laid the framework for transformative water treatment for plants around the world. Scale-up studies have shown that water treatment plants that use MFCs to process organic waste can produce enough energy to run the entire treatment process, cutting costs by 30 to 40%, as well as reducing the amount of leftover sludge by as much as 80%. The development of a more efficient technology that can achieve such energy savings across different water sources would greatly expand the implementation of this emerging technology. In addition to the positive effects this energy savings will have on the environment, this advancement will help expand water treatment options available to communities that lack the resources needed to realize alternative energy-intensive approaches that often require high capital and installation costs. Water treatment is among the most basic necessities for maintaining a healthy and high quality life; it is an area of ongoing advancement not only for developing communities, but also well-established cities. Any advancement made towards this end would therefore have a direct impact not only on small communities in need of extra energy, but on every inhabitant.

We engineered a collection of microbes with distinct electricity-generating pathways and compared their power generation in a bioelectrochemical system. We demonstrated an initial 3-fold improvement in power generation through the expression of a foreign electron conduit. We were then able to further enhance the performance of our microbe through the expression of a mixed conduit comprising of both foreign and endogenous parts. These different parts rely on distinct, yet complementary electricity-generating mechanisms that contribute to a synergistic increase in power production. Finally, we incorporated our bioengineered microbes into a MFC. The device was able to generate power from a wastewater collected from a local brewery. Moreover, the MFC based on the bioengineered microbes demonstrated a marked increase in performance compared to the state-of-the-art bioelectric microbes used in the industry, the latter of which were unable to survive in the wastewater.

Mouhib, M.; Reggente, M.; Li, L.; Schuergers, N.; Boghossian, A.A. Tailored extracellular electron transfer pathways enhance the electroactivity of Escherichia coli, bioRxiv, 2021 (under review).