In Dutch greenhouses, cucumbers are now being grown using nitrogen and phosphorus recovered from the sewage system. This experiment is part of the KNAP project by WUR, which aims to recycle nutrients from wastewater and process water. The project involves a broad collaboration with 46 partners.
Kimo van Dijk, coordinator of the KNAP project and associated with Wageningen University & Research, explains at Eurofins what's unique about fertilizing cucumbers with wastewater (link in Dutch). "The nitrogen and phosphorus used for growing these cucumbers are sourced from partners within the KNAP project. It is thus recovered from waste and process water. These nutrients have been made suitable for use in greenhouse horticulture using innovative techniques. The trial has been running for about two months now. The drain water from the growing system is recirculated, keeping the water cycle mostly closed as well. These cucumbers are therefore the product of a 100% circular process."