What if industrial waste could help clean polluted water and later become part of a fertiliser?
Researchers at Cracow University of Technology are exploring this idea through the international CleanLake project. The team is developing materials that can remove excess nitrogen and phosphorus from water. They are also testing whether these materials can later become components of controlled-release fertilisers.
The project connects three major environmental challenges: water pollution, industrial waste and sustainable agriculture.
Tackling the causes of eutrophication
Many lakes suffer from eutrophication. This process occurs when too much nitrogen and phosphorus enter an aquatic ecosystem.
These nutrients can trigger excessive growth of algae and cyanobacteria. As a result, water quality can deteriorate and aquatic ecos
ystems can suffer.
The CleanLake researchers want to capture these nutrients before they cause further damage. Their approach uses specially designed sorbents and zeolites that can capture nitrogen and phosphorus from water.
The researchers are also looking at an important question: where should these materials come from?
Turning waste into a useful material
The CleanLake team develops zeolites from industrial by-products and waste materials. These include fly ash and ash from biomass combustion.
Some of the resulting materials contain up to 80% waste-derived raw materials. The team has also developed a low-temperature synthesis method. The process uses temperatures of around 20–25°C.
The approach could help reduce the amount of industrial waste requiring disposal. It also uses a lower-temperature synthesis process than conventional hydrothermal methods.
The researchers therefore see waste as a potential resource rather than simply something to discard.
From water treatment to fertiliser
This idea becomes even more interesting after the sorbent does its job.
The material captures nitrogen and phosphorus from water, concentrating these nutrients in the sorbent.
Instead of treating the used sorbent as waste, the researchers are testing another option. They are investigating whether it can serve as a component of controlled-release fertilisers.
The team already runs plant experiments at Cracow University of Technology. Researchers grow plants
with fertilisers made from sorbent material that previously captured nutrients from water.
They compare the results with plants that receive commercial fertilisers. The experiments include crops such as wheat and rapeseed.
The researchers are testing whether captured nutrients can safely and effectively return to the agricultural cycle.
In simple terms, the researchers are exploring a circular loop:
industrial waste → water treatment → nutrient recovery → fertiliser → plant growth
This is the core idea behind a circular economy.
Taking the technology beyond the laboratory
The CleanLake team wants to test the technology in real environmental conditions.
Researchers are developing several possible applications. These include modular filtration and sorption systems for rainwater and surface runoff.
The team is also exploring underwater carriers with replaceable sorbent cartridges. Other concepts could integrate the materials into infrastructure around lakes and other water bodies.
The systems are already being tested in Poland and Germany, including in real-world conditions at Lake Kierskie in Poland.
In the future, similar systems could potentially help treat water in rivers, retention reservoirs and rainwater management systems.
The goal goes beyond removing pollutants. The team is exploring whether these systems can also recover valuable nutrients.
A Polish-led international research project
Cracow University of Technology coordinates the CleanLake project.
The international consortium brings together researchers and an industrial partner from Poland, Germany and Lithuania.
The Polish partners include Adam Mickiewicz University in Poznań and PROTE Technologie dla Środowiska. The international partners include Technische Universität Bergakademie Freiberg in Germany and Vilnius Gediminas Technical University in Lithuania.
The project is funded under the M-ERA.NET 3 Call 2023, with Polish funding provided by the National Centre for Research and Development (NCBR).
Researchers from several fields contribute to the project. Their expertise includes materials engineering, environmental engineering, chemistry and water treatment.
This collaboration reflects an important trend in modern research. Complex environmental challenges often require expertise from several disciplines.
Why does CleanLake matter?
The project offers more than a new approach to water treatment.
The researchers ask whether industrial waste can become a useful resource.
They also ask whether water treatment can recover nutrients instead of creating another waste stream.
Most importantly, the project connects three areas that often operate separately: water protection, waste management and agriculture.
The technology remains under research and testing. The team still needs to evaluate how the materials perform under different conditions and over longer periods.
Researchers also need to establish how safely and efficiently they can use the recovered nutrients in agriculture.
These next steps will determine how far the technology can move from research into practical applications.
For now, CleanLake offers an encouraging example of circular research.
Instead of seeing waste, polluted water and nutrient loss as separate problems, the researchers connect them into one potential solution.
From industrial waste to cleaner water, and from cleaner water back to the agricultural cycle, CleanLake explores what a more circular approach to environmental technology could look like.
And Polish researchers are helping to turn that idea into something that can be tested in the real world.
Photos: Courtesy of the CleanLake research team, Cracow University of Technology.
