The Road to Market Uptake of Circular Fertilisers – the Case of Struvite.

Struvite: a sustainable fertiliser for the future

Global agriculture is facing sustainability challenges and one of the practices that is being adopted to face them is the use of circular fertilisers. Struvite, a phosphate recovered from wastewater is one of the most known ones, due to the technology maturity of the production process that enables market potential. Moreover, struvite offers environmental benefits and agricultural potential, making it a promising alternative to conventional fertilisers. However, its success in replacing conventional fertilisers relies on its market potential, which depends on several factors.

Legislative support

The EU Fertilising Products Regulation (EU) 2019/1009 and specifically the Commission Delegated Regulation (EU) 2021/2086 (1) has provided a legal framework for struvite recovered from industrial and municipal installations for trading in Europe, and thus significantly boosting its market potential. This regulation sets standards for purity, safety, and labelling to ensure struvite is free from hazardous contaminants and properly informs users about its nutrient content. This regulation supports the safe and effective use of struvite in agriculture. With increasing regulations on synthetic fertilisers and the push for sustainable farming practices, struvite can become a preferred alternative.

Read this FER-PLAY report to dive into an extended analysis of the regulatory framework of struvite and 5 other circular fertilisers.

Dissemination of proven agricultural benefits

Struvite offers several advantages as a fertiliser:

1. Slow-release properties: Struvite demonstrates continuous phosphorus availability over time, making it an effective slow-release fertiliser (5).
2. Effectiveness in acidic soils: It has been shown to be particularly effective as a phosphorus fertiliser in soils with pH < 6(9).
3. Comparable performance: Studies have shown that struvite has similar or even superior fertilising potential compared to traditional fertilisers (8).

A recent study in Mediterranean soils found that struvite showed similar fertilisation capacity to conventional mineral fertilisation, with adequate plant growth and good nutrient concentration at the 50 kg P2O5 ha−1 dose (7).

Fertiliser Type	Nutrient Release Rate
Struvite	– Releases 50% of N in the first month (7)
	– Releases 53.5-73% of N at 16 weeks (7)
	– Considered a slow-release fertiliser (7)
Conventional KCl	– Releases 85% of K within 2 days (10)
	– Releases 90% of K within 5 days (10)
Urea	– Releases 85-90% of N within 5 days (11)
DAP	– Releases 65-75% of N within 5 days (11)

Awareness of environmental advantages

Struvite offers significant environmental benefits:

• Reduced nutrient loss: Its slow-release properties can help minimise nitrogen and phosphorus losses to the environment, which can be as high as 40-70% for nitrogen and 80-90% for phosphorus with conventional fertilisers (7).
• Lower GHG emissions: Under the same nitrogen application rate, struvite produces lower cumulative nitrous oxide emissions compared to urea (3)(4).
• Resource conservation: As a renewable resource, struvite contributes to the circular economy and reduces dependence on mined phosphate rock.

Industrial upscale

Phosphorus recovery as struvite from wastewater is often not the primary investment driver. Many other factors such as clogging problems, savings on operational and maintenance costs, and replacement of conventional coagulants play a vital role. Concentrated orthophosphate flows enhance recovery efficiencies, with operational costs being highly sensitive to chemical prices. Industrial struvite installations typically achieve faster returns on investment (ROI) compared to urban wastewater treatment plants.

In general, alternative fertilisers demonstrate significant potential to replace conventional ones, offering distinct advantages in nutrient content and soil enhancement. Economic and environmental considerations are crucial, as the primary commercial incentive for many technologies often lies in other factors rather than the fertilisers themselves.

Read this FER-PLAY report to get to know more about industrialisation potential of struvite and 5 other circular fertilisers.

Challenges and future outlook

Despite its advantages, struvite faces few challenges:

1. Limited availability: Currently, the major bottleneck for struvite is its low availability. It covers only 0.1% of EU agriculture’s phosphorus demand (2). An estimated 22% of global phosphorus demand could be satisfied by recovering from domestic wastewater worldwide (1) so there is huge potential. 
2. Market awareness: Farmers and industries may lack awareness of struvite’s benefits, making it challenging to establish a reliable market. Investing in educational campaigns and demonstrations can build trust and generate demand.
3. Price variability: Prices for struvite can vary, depending on the market and application.
4. Recovery efficiency: Current struvite precipitation methods cannot capture all phosphorus contained in wastewater treatment by-products, leading to some phosphorus loss. Though, the process of struvite recovery may also yield other marketable by-products, such as treated water or nitrogen-based compounds, further enhancing profitability.

To maximise struvite’s potential as a sustainable fertiliser, efforts should focus on expanding its production in wastewater treatment plants due to the operational benefits. Strategic partnerships with treatment facilities might ensure a steady supply and streamline logistics. Improving phosphorus recovery efficiency by investing more in R&D and conducting long-term field trials to demonstrate its effectiveness across various crops and soil types. Struvite can be integrated with other nutrients to create customised blends for specific crops, enhancing its value and market appeal.

In conclusion, struvite represents a promising step towards more sustainable agricultural practices. As research continues and production scales up, this innovative fertiliser could play a crucial role in addressing global food security while minimising environmental impact.

References

1. Delegated regulation – 2021/2086 – EN – EUR-Lex. (n.d.). https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=celex%3A32021R2086
2. Susfert. (2023, November 15). Struvite – wastewater to fertiliser – Susfert.eu. Susfert.eu. https://www.susfert.eu/struvite-wastewater-to-fertiliser/
3. Yang, Z., Ferron, L. M., Koopmans, G. F., Sievernich, A., & van Groenigen, J. W. (2023). Nitrous oxide emissions after struvite application in relation to soil P status. Plant and Soil, 1-15.
4. Wang, L., Ye, C., Gao, B., Wang, X., Li, Y., Ding, K., Li, H., Ren, K., Chen, S., Wang, W. and Ye, X., 2023. Applying struvite as a N-fertilizer to mitigate N2O emissions in agriculture: Feasibility and mechanism. Journal of Environmental Management, 330, p.117143.
5. SUSFERT. (n.d.). STRUVITE — Contribution to the circular economy. Retrieved from https://www.susfert.eu/struvite-contribution-to-the-circular-economy/
6. SUSFERT. (2023, May 17). Struvite – wastewater to fertiliser. Retrieved from https://www.susfert.eu/struvite-wastewater-to-fertiliser/
7. Pérez-Piqueres, A., et al. (2023). Struvite as a Sustainable Fertilizer in Mediterranean Soils. Agronomy, 13(5), 1391. https://doi.org/10.3390/agronomy13051391
8. Notenboom, G., et al. (2021). An integrated assessment of scaling up struvite recovery at WWTPs in the Netherlands. Retrieved from https://edepot.wur.nl/640119
9. Jama-Rodzeńska, A., Gałka, B., Szuba-Trznadel, A. et al. Effect of struvite (Crystal Green) fertilization on soil element content determined by different methods under soybean cultivation. Sci Rep 13, 12702 (2023). https://doi.org/10.1038/s41598-023-39753-8
10. Bley, H., Gianello, C., Santos, L. D. S., & Selau, L. P. R. (2017). Nutrient release, plant nutrition, and potassium leaching from polymer-coated fertilizer. Revista Brasileira de Ciência do Solo, 41.
11. Niedziński, T., Sierra, M. J., Łabętowicz, J., Noras, K., Cabrales, C., & Millán, R. (2021). Release of nitrogen from granulate mineral and organic fertilizers and its effect on selected chemical parameters of soil. Agronomy, 11(10), 1981.
12. Qadir, Manzoor, et al. “Global and regional potential of wastewater as a water, nutrient and energy source.” Natural resources forum. Vol. 44. No. 1. Oxford, UK: Blackwell Publishing Ltd, 2020.