What is a bioreactor? It sounds complicated, but it’s really a two dollar word for something that pumps air through algae. There’s a few designs on YouTube, this is my home brew variation of those.

On a large scale, bioreactors can help scrub CO2 and some pollutants from the air and return oxygen. The air is pumped via a compressor, through a solution containing algae. The algae takes the CO2 and uses it for growth and in return, gives off oxygen which is released back into the surrounding air.

We have ours connected to our solar setup so the power to run it is free.

I made one recently, a very simple proof of concept and thought I’d share it here in case you want to try your own.


My home made bioreactor


What you need:

  • Transparent container
  • aquarium hose
  • iron or steel weight
  • aquarium air pump
  • Algae
  • Water


That’s it. Pretty simple. Here’s how it goes together:

The water and algae go into the transparent container. I used two 11 litre plastic spring water containers.

Attach one end of the aquarium hose to the weight and lower it into the water so the weight is at the bottom of the container. This holds the hose at the bottom of the tank. Also, as it rusts, the weight releases small amounts of iron into the water to feed the algae.

Attach the other end of the hose to the pump, turn on the power and watch the bubbles!

That’s it, you’ve got a bioreactor!

Of course, it can get as complicated as you like. You can:

  • make a loop of hose at the bottom of the tank to distribute the air more evenly
  • vary the shape of the containers to increase the time the air is kept in the solution
  • experiment with different types of algae
  • bounce light onto the container, or use powered lighting
  • play around with the airflow
  • use multiple containers, like I did

If anyone can suggest a way to measure the amounts of CO2 going in and O2 coming out using home brew technology, I’d love to learn from you.

Bioreactors…fun for all the family!