Dutch horticultural projects recover fertilizer from wastewater
“Closing the loop reduces the dependence on primary fertilizers, which have become more expensive and have a relatively large environmental footprint,” Karel de Bruijn said, as onderglas.nl reported. Agricultural businesses and knowledge institutes are collaborating to extract valuable nutrients from waste streams to supply the Dutch horticultural sector.
The joint effort operates under the public-private partnership project known as KNAP, which translates to the nutrient closed-loop recovery from wastewater and process water initiative. Launched in 2023, the project reaches its final year of development with technical feasibility established for recovering nutrients from organic waste streams and wastewater. Participants have successfully tested the recovered materials in plant production systems, including greenhouse horticulture.
Bioreactors produce calcium nitrate from manure
Project developers have built specialized bioreactors designed to manufacture calcium nitrate using nitrogen extracted from animal manure and sewage sludge. Trials have also successfully evaluated the direct application of recovered phosphoric acid. Raw materials such as animal manure, sewage sludge, and purification water from municipal wastewater treatment plants remain widely available across the region.
Teeltproeven conducted within innovation centers show that these recovered nutrients can serve as safe alternatives to conventional mineral fertilizers.
North American organic methods inform Dutch trials
Production processes and raw material utilization strategies developed across North America provide valuable technical input for the Dutch market.
Interest among individual horticultural businesses and grower associations continues to increase, aligning with initiatives such as 100% Groen Geteeld. Regulatory frameworks still require adjustments to remove current operational limitations, though political support for these changes appears to be growing.
Frequently asked questions about circular fertilizers
When did the KNAP nutrient recovery project begin?
The public-private partnership project started in 2023 and concludes its final phase.
Which raw materials are used to create the fertilizers?
Developers use animal manure, sewage sludge, and purification water sourced from wastewater treatment facilities.
Where did the foundational production methods originate?
Initial techniques were developed in Canada and the United States, where substrate growing is common in organic agriculture.
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