Summary of the Deliverable

The WalNUT deliverable D1.4 (“Barriers on Bio-Based Fertiliser (BBF) Development”) provides a Europe-wide mapping of the obstacles that prevent nutrients recovered from wastewater (WW) streams from being transformed
into marketable BBFs. The study first carried out an extensive literature review of the EU-27 matrix of nutrient-recovery (NR) technologies (produced in the previous D1.3 task) to identify the technical, economic and regulatory pre-
conditions that underlie any NR deployment. Building on this baseline, a purpose-designed questionnaire was prepared for each of the six stakeholder groups that constitute the BBF value chain—WW producers, WW-treatment
plant (WWTP) operators, fertiliser manufacturers, end-users (farmers and agricultural associations), technology providers and policy makers. The questionnaire was split according to respondents’ previous experience with NR,
resulting in four response groups that were processed systematically; the survey was administered both on paper and online via Google Forms.

The collected data were then analysed using mixed quantitative (ranking, percentages) and qualitative (open-ended comment) methods, allowing the authors to allocate “lock-ins” and barriers for each actor, to identify the most
relevant pre-conditions, and to evaluate a set of proposed measures and motives for BBF uptake.

The analysis revealed a clear hierarchy of barriers that affect the whole supply chain. The most frequently cited obstacle (approximately 35 % of interviewees) is the limited accessible commercialization pathway or market for recovered
nutrients, i.e. the absence of a well-defined sales channel and of reliable demand from fertiliser manufacturers. The second-most important barrier (approximately 28 % of interviewees) is high total operational expenditure (OPEX), encompassing maintenance, energy, chemicals, labour and disposal costs. Initial capital expenditure (CAPEX) for advanced NR equipment also appears repeatedly, together with questionable quality and safety of recovered
nutrients due to contamination risks from potentially toxic elements, PAHs, pharmaceutical residues and microbiological pathogens.

Additional constraints include fragmented or heterogeneous national and regional regulations, which raise compliance costs and hinder cross-border trade, lack of awareness of recent regulatory updates and of future restrictions on mineral fertilisers, and a deficit in engineering expertise and knowledge of NR options. Together, these factors explain why many WW producers and WWTPs have not yet implemented NR technologies.

To overcome the identified bottlenecks, the survey asked participants to rank a series of policy and market measures. The option receiving the strongest consensus is the obligation to use recovered nutrients first instead of mineral
fertilisers, indicating that a mandatory “use-NR-first” rule would be a decisive driver for deployment. The second most supported measure is the enactment of a minimum NR-content requirement in BBFs together with a price
guarantee, which would reduce market uncertainty for both producers and end-users. Other well-received proposals include direct financial support for scaling-up innovative NR technologies (CAPEX and OPEX), tax incentives on
mineral fertiliser use, and stricter wastewater disposal criteria that would push operators toward nutrient recovery.

These measures were visualised in Figure 3-2 of the deliverable, highlighting the relative weight of each recommendation among the interviewees.
Motives that could encourage actors to adopt NR and BBF solutions were also examined. For WW producers and WWTPs, the strongest drivers are the availability of a guaranteed market and value for recovered nutrients, the
environmental friendliness of the practice, and financial support from political institutions to share innovation risk. Fertiliser manufacturers and end-users (farmers and agricultural associations) emphasise the need for high nutrient
density, certified product quality, price competitiveness with mineral fertilisers, and clear regulatory certainty; lack of these factors was repeatedly linked to low acceptance of BBFs. Technology providers highlighted that economies of scale,
direct financial help, and tax benefits would make it easier to bring NR-based products to market.

The deliverable concludes that the principal barrier across the value chain is the absence of a clear commercialization pathway, followed by the high OPEX and CAPEX of NR installations and quality-safety concerns about the recovered
streams. Moreover, regulatory fragmentation and low awareness of recent EU rules (such as the Fertilising Products Regulation 2019/1009) further impede progress. The authors recommend harmonising national regulations,
establishing robust certification and traceability procedures for recovered nutrients, and implementing the most supported policy levers (mandatory “use-NR-first”, minimum NR-content with price guarantees, financial incentives, and stricter discharge standards). By addressing these lock-ins, the EU could transform wastewater-derived nutrients into a viable, circular source of fertiliser, reducing dependence on imported mineral resources and supporting the broader European Green Deal objectives.

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Download the Full version of the Deliverable here.