The potential of struvite in Dutch agriculture

The Netherlands Enterprise Agency (RVO) is keen to understand the ins and outs of struvite production in the potato-processing industry and asked CE Delft to summarize available knowledge from a range of sources in a report providing a thorough picture of the potential of struvite recovered by the potato-processing industry as an alternative fertilizer for Dutch agriculture.

The Netherlands processes 3.5 million tonnes of potatoes annually. The blanching water generated in the process contains struvite that can be recovered, a process currently operated by two companies in the Netherlands. Struvite can be used as an alternative to agricultural fertilizers, including in potato cultivation, representing a step towards closing nutrient cycles and, by contributing to sustainable materials management, towards the circular economy. Application of struvite means less extraction of phosphate ore, a finite resource.

Because of its eco-friendly profile and slow-release properties, struvite is very suitable for use on organic farms, in horticulture and ornamental plant cultivation, in grass sward production, on golf courses and football pitches and by consumers. Its limited availability may be perceived as a drawback, though, and the same holds for the slow release in some applications. To improve market acceptance, the potato-processing industry could demonstrate proof-of-process on a test site.

Member companies of the Dutch Association of Potato-Processing Industries (VAVI) have stated that they no longer see any legal barriers to marketing struvite as a fertilizer, though the process will need to be formally registered. There is one legal bottleneck, however, as struvite may not be applied in liquid form. Potato plant effluent used to be applied directly on farmland, but this is no longer permitted in the Netherlands. In neighbouring countries this is still practised, though.

Potato processors recovering struvite from effluent to produce struvite cake for use as fertilizer realize energy savings of 32.54 GJ/tonne struvite and carbon savings of 1.5 tonne CO2-eq./tonne of struvite.