Imagine cleaning dirty water with a plant… without needing big, heavy tanks of water. That’s the idea behind IMPRESS’ latest research paper published by Iván Loaiza and Marcel A.K. Jansen from University College of Cork in the International Journal of Phytoremediation. In short, It tests “fog-o-ponic” duckweed farming.
What the paper is about
The researchers looked at duckweed (Lemna minor L.), a fast-growing floating plant already famous for soaking up excess nitrogen (N) and phosphorus (P) from wastewater. What’s the catch? Most indoor duckweed systems still rely on trays full of water, and stacked “multi-tier” versions get engineering-heavy because every layer has a column of water weighing it down.
Why fog-o-ponics?
Fog-o-ponics bears similarities to aeroponics, yet it utilises a nutrient mist instead of roots sitting in liquid. They placed duckweed colonies on a nylon mesh “hammock,” and a nutrient solution was turned into a fog using an ultrasonic mister. If it works, thin plant layers can be stacked with far less weight, potentially making compact, year-round, indoor “living filters” that fit circular-economy goals, to treat waste streams and turn nutrients into biomass. In the process a three-layer prototype (with 2 cm spacing) was built to explore how stacked cultivation might perform at different heights.
How they tested it (and when)
Short trials were run to see how light levels and fogging schedules affected growth and longer trials up to 21 days checked if plants stayed healthy over time. As the fog itself can block light, with a potential ten-fold reduction report, light intensity was tuned to avoid starving the plants.
What they found
Duckweed didn’t just survive, it grew about as well as in traditional liquid culture. Best performance hit a relative growth rate of ~0.24 per day at 50 µmol m⁻² s⁻¹ light, with photosynthesis health indicators comparable to “normal” growth. Continuous misting beat on-off cycles, suggest steady fog helps keep nutrients available. Crucially, the plants removed lots of nutrients, with the paper reporting total nitrogen removal of around 500 mg per square meter per day, noting substantial N and P uptake into plant tissue.
What this could mean next
If scaled up, fog-o-ponic duckweed could become a high-capacity, multi-stacked wastewater polishing step for farms, food processing, or indoor treatment facilities, turning “pollution” into harvestable biomass, for fertilizer, feed ingredients, or bio-products. The paper also flags questions, like maintaining fog delivery and lighting efficiently at industrial scale, but it’s a promising proof-of-concept for lighter, denser phytoremediation reactors.
Read the full publication ⤵️
Fog-o-ponic cultivation of duckweed (Lemna minor L.): an innovative technique for phytoremediation
This summary was written by reframe.food.