Chlorella Vulgaris - An Experiment in CO2 Reduction

The purpose of growing Chlorella Vulgaris is a bit of a combination of things for me. I’d been reading about air quality and the impact high CO2 levels can have on concentration and ability to work. So I started looking for ways to change the gas composition in my home to decrease CO2 levels and increase O2 levels. I came across a few academic papers which talked about methods for CO2 scrubbing and O2 production onboard space stations and growing Chlorella Vulgaris was one of the most efficient methods that had been identified.

I figured if it’s good enough for use on a space station, it’s more than good enough for use here on the ground! According to the math I’d need about a 400L setup to effectively counter all CO2 production within my home, which is an interesting idea, but I don’t want to mess with the gas composition quite that much. So I’m aiming for a 50L setup as a medium term goal.

Initial Setup

To get started I needed to have an environment that provided continual flow of air through a container of liquid which would house my algae. For this purpose I turned to AliExpress and ordered some fairly cheap components:

• 5m of 4mm aquarium tubing
• 2x filters – I would not get this type again, disc/membrane filters would be more appropriate
• 2x bottle caps
• 1x aquarium pump with internal battery backup

Once these items had arrived, I added some filtered water and cobbled them together into the following arrangement:

Once assembled I sterilized the environment by placing the unit into an ozone filled chamber under UVC lighting

I then let the pump run for a week to ensure that nothing else was growing in there.

Adding the Algae

I ordered a starter kit from Aquatic Live Food. The kit arrived within a few days.

Note: instruction sheets were included but not are pictured

Following the directions included, I sterilized the area, instruments, and containers I would be working with. For this I used a 70% isopropyl alcohol and water mixture. I then mixed the growth media with 1 L of water. I filled the included Corning slide bottle with 30 mL of the mixed growth media, and 20 mL of the Chlorella Vulgaris sample.

With the remaining Chlorella Vulgaris I went off script and tried something else, placing 2.5 mL of the Chlorella Vulgaris in each of the two bottles I had set up with the airpump, along with 50 mL of the growth media. I topped up the Chlorella Vulgaris sample bottle with growth media as well. This way I figured I had four cultures, thus increasing my chances of success

Progress

Over the next week I would shake the two smaller bottles three times a day (as per the included instructions) and monitor the progress of the four cultures

Splitting

At this point I decided to split the cultures off as it was becoming a bit hard to determine progress as all of the samples had become quite dark. To do this I ordered additional culture media and made up 1 L as I had before.

I split the 1L between four bottles which I had sterilized and cleaned, I added the growth media and then added 1 mL of liquid from each of the four cultures to the bottles

Scaling Up

I’ve done the following

• Swaped to 2x 2L bottles
• Swapped to membrane filters
• Added a new 1.25L bottle which has the groth media and 1mL of algae from one of the existing bottles

I look forward to seeing it get nice and green like the others.

Future Plans

The next steps I have planned are to scale things up. I will swap to a better air filtration system and move to a larger vessel. My plans on this are still being formed, I will update as things progress