Ever stood near a body of wastewater?

I cannot imagine the stink and the filth that accompanies it.

Wastewater stinks partly because of the activity of microscopic organisms – bacteria.

These miniature creatures are anything but docile.

They are energetic and work overtime.

Their energetic drive comes courtesy of a process called metabolism.

METABOLISM

Metabolism means breakdown of food stuff to produce energy.

It happens each and every second in our bodies as long as we breathe.

But it happens on overdrive mode in some microbes because they don’t utilize oxygen like we do.

This is the realm of anaerobic metabolism.

When oxygen is used, the byproducts are water and carbon dioxide (which is what we breathe out).

But when oxygen is in short supply, these special bacteria (also called anaerobes) produce a mixture of lactic acid and electrons.

Now the flow of electrons equals current which equals energy.

Which is why microorganisms and wastewater are a formidable match.

MICROBIAL FUEL CELLS (MFCs)

So what happens when we seal a container with wastewater and insert a conductor like copper, aluminum or carbon?

These anaerobes attach themselves to these conductors and release electrons from metabolism

But since these are conductors, these electrons are easily carried by them in an external circuit.

If we connect this conductor to another conductor and expose it to air, current will flow.

This is the microbial fuel cell – a device that derives power from the action of bacteria.

See photo below.

But microbial fuel cells don’t just derive power from bacteria, they simultaneously ‘clean’ wastewater in the process.

You see the dirt in wastewater we see as a pollutant is food for bacteria.

So if bacteria breakdown this dirt and release energy, over time, the dirt will reduce as more energy is produced.

Of course this is the ideal situation which has not yet become reality.

This is because of a few reasons.

First, for reasonable current to be generated, it must be facilitated by low resistance.

Resistance is blockage of current flow.

By nature, MFCs have a high internal resistance because a very small amount of electrons from metabolic activity are captured.

Secondly, for reasonable current flow, there must be a mechanism to allow exchange of ions between the two chambers.

This is facilitated by a special type of salt bridge.

However, still with these challenges, some MFCs have been tested and known to generate slightly less than a volt – which is not yet economically useful.

However, if production of energy could be coupled with removal of pollutants, then commercialization of this technology is feasible.

POLLUTANT REMOVAL

MFCs have been used to remove several pollutants from wastewater such as toxic heavy metals, agricultural nutrients, antibiotics, pesticides etc.

In other words, what if we view these pollutants as a potential energy source through MFCs?

R&D FOR OPTIMIZATION

But also, there is need to optimize some of its features such as the conductors (or electrodes) and the salt bridge which could be done through research.

These are areas open for engineers, biologists, chemist’s, physicists to venture into.

Tools such as nanotechnology and material science are key in this regard.

It’s one practical way of solving multiple problems at the same time:

Managing waste, generating energy and cleaning wastewater.

IN CONCLUSION

MFCs might be a technology still under the radar.

However, it’s potential lies in its ability to tackle multiple problems at the same time.

My hunch is it has a bright future only only if a few visionaries are willing to invest their time and money to make it fit for commercialization.

Cover photo credit: CDC via Pexels