Scientists say yeast and green algae improves water treatment

The researchers, led by Associate Professor Ryosuke Yamada from the Graduate School of Engineering, set out to find the most effective combination of microorganisms for wastewater treatment.

They tested various combinations of microorganisms to determine the most effective pairing. The team measured the removal rates of key pollutants like organic carbon, phosphate, and ammonium.

Key findings​

The study revealed that the combination of the green algae Chlamydomonas reinhardtii and the yeast Saccharomyces cerevisiae produced the highest efficiency in wastewater treatment. The combination achieved high removal rates for total organic carbon (82%), phosphate (93%), and ammonium (71%).

This high efficiency in removing nutrients like nitrogen and phosphorus helps prevent eutrophication, which can cause harmful algal blooms and oxygen depletion in aquatic ecosystems.

Greener and cleaner ​

This research is significant because it offers a more energy-efficient and environmentally friendly approach to wastewater treatment.

The combination of green algae and yeast eliminates the need for aeration, which typically requires substantial electricity in traditional activated sludge methods.

Additionally, both microorganisms are safe for humans and the environment, making this a potentially attractive option for sustainable water treatment.

As well as possibilities for developing more efficient wastewater treatment technologies, the discovery opens up the possibility of potentially producing useful compounds as a byproduct of the treatment process

The biomass produced by the yeast and algae during treatment can be utilized in various ways, such as microbial fertilisers, for bioenergy production, and as a source of valuable compounds like polysaccharides, fats, and oils.

This aligns with circular economy principles, turning waste into useful resources.

“The green algae and yeast are highly safe for humans, especially considering that treated wastewater is discharged into the environment,” Professor Yamada explained. “These microorganisms can also accumulate useful compounds such as polysaccharides, fats, and oils in their cells, and be used as microbial fertilisers, so it is possible to expect useful compounds to be produced at the same time as the wastewater is being treated.”

The findings were published in Applied Microbiology and Biotechnology​.