The only thing standing between wastewater and its new life as a nutrient-rich fertilizer may be streams of tiny, tiny bubbles.
This is the novel takeaway from a recent study which focuses on an emerging new approach: plasma bubble technology. This technology can purify water, while retaining its crop-benefiting nutrients. What’s more, when researchers tested the resulting purified and concentrated feed on hydroponic garlic crops, they noted that the plants had notably faster and healthier growth.
In general terms, plasma bubble technology works by pumping ionized gas into water, which creates millions of microscopic bubbles that course through the water, reacting in different ways with the ingredients within it. It’s this reaction that is key to its water-purifying qualities: the bubbles have the ability to degrade organic contaminants in the water. But, they’re also able to fix nitrogen, a key agricultural nutrient.
For their study, the University of Alberta researchers sourced wastewater from the malting industry, which produces spirits and beer. This byproduct is rich in organic elements, including nitrogen. But while one of these—nitrogen—accelerates crop growth, the researchers note that the remaining organic load could put growing plants under strain.
So, they tried their plasma bubbles, using a patented version of the technology that they have developed, which uses an electric pump and is fully automated. After pumping the malt wastewater full of tiny bubbles, the researchers found that the water’s organic load had been reduced by 90%, but the ionized bubbles increased the total levels of nitrogen in the water to 53.1 mg per litre through nitrogen fixation, almost double the amount in the control experiments.
Then it was time to put their nutrient-enriched water to the test. In an experimental hydroponic set up, the researchers watered 36 garlic plants, germinated from bulbs. They found that compared to the control plants, the plasma-wastewater treated bulbs germinated sooner, and developed longer roots.
Tests on the plants revealed that the treated garlic bulbs had assimilated more nutrients than the others, confirming the nutrient-rich status of the bubbled water. This showed up in the garlics’ continued growth, with the biomass of treated plants almost doubling that of the others.
The scientists think their automated system is a good fit for hydroponic crop production, and could work for a range of other plants grown in this setting, they believe.
Like many of the best solutions, theirs dovetails two in one. “The technology performs the dual function of treating the wastewater and converting it into a nutrient solution that supports hydroponic crop production,” the authors say. “In this way, the treated wastewater becomes a valuable agricultural resource instead of a disposal problem.”
Zhang et. al. “Microbubble-enhanced cold plasma activation of food-industry wastewater for valorization and hydroponic crop production.” Green Chemical Engineering. 2026.
Image: cottonbro studio via pexels
