Short Video showcases circular solutions to reduce pollution, energy use and Europe’s import dependency

A new video news release from the WalNUT project highlights an innovative approach to fertiliser production that could reduce mineral fertiliser use by up to 25%, while helping Europe decrease pollution, lower energy consumption and curb reliance on imported resources.

The under 4-minute video is available here.

In western France, farmers are experimenting with an unconventional fertiliser: a powder made from algae grown on wastewater. The results are encouraging: when mixed with mineral fertilisers, this bio-based product can reduce their use by up to 25% without sacrificing yields.

“We grew unicellular algae on dairy effluents from a food processing plant,” explains Orhan Grignon, agriculture and environment advisor at the Chamber of Agriculture in Charente-Maritime. "The algae feed on the organic matter in the wastewater, turning it into plant biomass. We then dehydrate that biomass and spread it on fields as a fertiliser, since it’s naturally rich in nitrogen.”

Field tests carried out on wheat plots compared algae powder with mineral fertilisers and other organic products. The results show that while algae alone does not match mineral fertilisers in terms of yield, combining the two delivers equivalent results, while cutting mineral fertiliser use by a quarter.

These trials were conducted within WalNUT, a European project aimed at giving wastewater a second life. “Our main objective is treating different kinds of wastewater, such as industrial effluents, urban wastewater, or brines,” explains its coordinator, Francisco Corona Encinas.

“By applying a circular approach, we not only reduce the pollutant load of these processes but also add value to the nutrients contained in them, using these nutrients as biofertilisers in agriculture.”

A further example of this circular approach is underway in Ourense, northern Spain, home to one of Europe’s most advanced water treatment plants. Here, nutrient recovery is being implemented on a large scale. “In this facility of nearly 30,000 square meters, more than 600 liters of urban wastewater arrive every second,” explains Alicia González Míguez, project manager at CETAQUA.

By recovering nutrients and developing bio-based fertilisers, Europe can reduce environmental impacts, strengthen food system resilience and decrease dependency on external suppliers. While further research is needed to optimise these solutions, early results demonstrate clear potential. From algae grown on industrial effluents to nitrogen extracted from municipal wastewater, these innovations illustrate how circular approaches can help close the loop between waste and food production.

The under 4-minute video is available here.

About WalNUT:

The WalNUT project is dedicated to closing wastewater cycles for nutrient recovery, developing bio-based fertilisers that support sustainable agriculture and reduce reliance on finite nutrient-mineral reserves. By promoting circular economy principles, WalNUT aims to mitigate environmental impacts while ensuring food security for the future.