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Microbial Fuel Cell

Tersa Earth was a biotech R&D startup that had grown out of a UBC research lab. They had engineered two unique bacterial strains and a biochemical process around those strains. The process allowed them to both reclaim valuable metals in solution and treat acid rock drainage (ARD) from pit lakes in mines with low C02 emissions.


Tersa had demonstrated their Microbial Fuel Cell (MFC) technology in a lab setting. Tersa came to us with a 300 ml lab scale proof-of-concept and a desire to scale up to a mine site scale prototype.

Project Roadmap

Motus worked with Tersa to establish the areas of risk, and applied the concept of Technology Readiness Levels (TRLs) to all the constituent technologies that had been developed toward the envisioned TersaClean system.The majority of Tersa technology was at the TRL-4 Level, and needed a roadmap of verification of engineered concepts that would deliver the process, function, feasibility and scale-ability of the technology. 
A 1000L TersaClean system would require all systems to be at a TRL of 7.


The Microbial Fuel Cell was identified as the key “big ticket” subsystem.  This subsystem is at the core of Tersa’s unique value proposition of reclaiming valuable metals from mine ARD ponds. Scaling up the Microbial Fuel Cell technology required scaling of Tersa’s proof of concept lab prototype by a factor of 10.

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The Design

Motus explored and refined several mechanical concepts, analyzed fluid dynamics to improve electrochemical performance, designed custom electronics, and developed a custom modbus interface, a PLC/SCADA system and a custom interface to Tersa’s Grafana database. Four months after project launch Motus delivered the instrumented MFC Lab System to Tersa Earth. 


Experimentation uncovered several improvements to be made to the MFC, specifically modularity and reliability.

Rapid Prototyping

In version two, the MFC case design is welded to minimize the need for gaskets and o-rings. Issues with managing differential pressure limits and sealing of the proton exchange membrane were addressed with a combination of mechanical design changes and additional sensors.


On a user workflow level, we worked with Tersa to refine the sterilization, flushing, priming and experimental procedures. This is to ensure the Human Machine Interface (HMI) interactions were safe, ergonomic, and that all of the detailed features needed were included to facilitate these procedures in the lab. Improvements were made to automate the experimentation/verification process, including digitally controlled load resistance, automation of flow rates, a new SCADA interface and improved integration of all sensor data.

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On to Experimentation

The final Microbial Fuel Cell Lab System V2 was delivered to Tersa to continue their in-lab optimization and validation experiments.

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