The Deliverable (D) 1.1 was developed under Work Package 1 (WP1) of the WalNUT Project, led by CARTIF in collaboration with the project partners including APCA, CETAQUA, UGent, NTUA, SDU, UCPH, UNITO, and ITACYL. The WalNUT project, funded under the Horizon 2020 program, aims to close waste water nutrient cycles and promote the recovery of nitrogen (N) and phosphorus (P) for sustainable agricultural use.

This deliverable focuses on analysing nutrient flows and imbalances in waste water treatment plants (WWTPs) across the EU. It provides an inventory of nitrogen (N) and phosphorus (P) stocks and flows from both urban and industrial waste water streams. The study assesses the potential for replacing chemical fertilisers with recovered nutrients, evaluates the geographical distribution of nutrient supply and demand, and highlights data gaps in current monitoring practices.

The study initiates with establishing a baseline by analysing the demand for inorganic fertilisers across EU member states. The total EU demand for nitrogen fertilisers is ~12.2million tons per year, while phosphorus demand stands at ~1.54 million tons per year.Following to that, the study evaluates waste water as a nutrient source, showing that significant amounts of N and P are discharged from urban and industrial WWTPs.However, there is a mismatch between nutrient supply (from WWTPs) and agricultural demand, necessitating better nutrient management strategies.

The findings indicate that 5.5% of the EU’s nitrogen demand and 13% of the phosphorus demand could theoretically be replaced by recovered nutrients from waste water treatment. Some regions, particularly industrialised and urban areas, have highernutrient recovery potential than others. The largest releases of nitrogen and phosphorus come from Spain, France, Germany, and Italy, while agricultural regions such as Castillay León (Spain) and Lombardy (Italy) have high nutrient demand but limited waste waternutrient availability.

Key Country-Specific Results

• Denmark: The highest agricultural demand is in Syddanmark and Midtjylland,but waste water nutrient recovery potential is relatively low.
• Spain: Castilla y León has the highest demand for N and P, but waste water nutrient supply is insufficient, requiring logistical solutions for redistribution.
• Belgium: Flanders has the highest nutrient demand, particularly in West-Vlaanderen and Hainaut, though urban WWTPs provide a moderate supply.
• France: Pays-de-la-Loire and Bretagne show high agricultural demand and good potential for localised bio-based fertiliser integration, while Île-de-France and Nord-Pas-de-Calais require efficient nutrient transport.
• Greece: Thessaly and Central Macedonia have high agricultural demand, but low nutrient availability from waste water sources.
• Hungary: The Dél-Alföld and Észak-Alföld regions have high crop nutrient demand, but waste water sources provide only limited supply.
• Italy: Lombardy, Emilia-Romagna, and Veneto have strong waste water nutrient availability, while Southern regions (Calabria, Basilicata, and Puglia) face supply shortages.
• Portugal: The Alentejo and Lisbon Metropolitan Area have higher phosphorus recovery potential, exceeding the EU average, making them key areas for circular economy initiatives

Conclusion and Next Steps

The study highlights critical data gaps and the need for more precise nutrient tracking.There is an urgent need for improved nutrient management, integrating smart logistics and policy frameworks to better match nutrient supply with demand. The WalNUT project’s future work (D1.2) will provide a detailed regional analysis to guide policy recommendations and technology deployment for increase nutrient recovery.

This deliverable underscores the potential of WalNUT technologies to reduce excess nitrogen and phosphorus flows, promote sustainable agriculture, and decrease EUreliance on synthetic fertilisers.

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