Microbubble-enhanced cold plasma activation transforms wastewater into green liquid fertilizer

A team of researchers from University of Alberta in Canada has developed an automated plasma-bubble technology that can transform wastewater into nutrient-rich fertilizing medium for crop production. Published in the journal Green Chemical Engineering, the study demonstrates how cold plasma can be integrated with microbubbles to intensify the plasma-liquid interaction, transforming industrial wastewater into a reusable fertigation medium for plant growth in hydroponic system. This was achieved via an electrified microbubble-enhanced cold plasma activation (MB-CPA) system which introduces green nitrogen-based reactive species.

"The modern agriculture is still relying on synthetic fertilizers and freshwater, while we discard huge volume of valuable nutrient-rich wastewater every day due to high organic loads," explains corresponding author, Professor Xuehua Zhang. "Our MB-CPA technology can solve these multiple challenges in one go."

The team's patented electrified MB-CPA technology uses air and forms tiny bubbles, which carries oxidative reactive nitrogen and oxygen species. These species degrade organic contaminants while simultaneously fixes vital bioavailable nitrogen in wastewater.

"The technology performs the dual function of treating the wastewater and converting it into a nutrient solution that supports hydroponic crop production," says Zhang. "In this way, the treated wastewater becomes a valuable agricultural resource instead of a disposal problem."

The researchers worked on medium-strength wastewater generated from malting industries. "The MB-CPA integrated with hydroponic system reduced organic loads and suspended particles, while generated nitrate which is the most available and essential nitrogen compounds for plant growth," adds Zhang.

The researchers also observed a faster and higher germination of garlic sprouts—nearly double the biomass—and higher sulfur nutrient content. Notably, the entire system can potentially support a wide range of plants and vegetables cultivated in hydroponic water-based systems.

"Because the process is automated, the system needs less oversight and is operable on renewable energy sources—this demonstrates its potential for scalable and sustainable agriculture," Zhang says.

The researchers believe the technology could help advance circular agricultural systems where wastewater, nutrients, and renewable electricity are integrated to reduce environmental impact while supporting food production.

Contact author details:

Xuehua Zhang, Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Canada, xuehua.zhang@ualberta.ca

Funder: 

This work was supported by Alberta Innovates, the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canada Research Chairs program, and the Canada Foundation for Innovation (CFI).

Conflict of interest:

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

See the article: 

Panchal, D., Han, S., Luk, H., Heo, Y., Zhang, X. Microbubble-enhanced cold plasma activation of food-industry wastewater for valorization and hydroponic crop production. Green Chemical Engineering (2026). https://doi.org/10.1016/j.gce.2026.03.001