Understanding Users and Societal Acceptance in Circular Sanitation Systems
The transition towards circular nutrient management systems linking urban sanitation with agricultural production has gained increasing attention as a pathway to reduce environmental pressures and enhance resource efficiency. However, beyond technological feasibility, the successful implementation of such systems depends critically on user and societal acceptance. Evidence from the P2GreeN project highlights that acceptance is not a secondary consideration, but a central condition for scaling up source-separating sanitation and human excreta-derived fertilisers.
Acceptance in the Context of Circular Nutrient Flows
Circular sanitation systems challenge conventional linear models by reframing human excreta as a resource rather than waste. While this shift offers proved environmental benefits, such as reducing nutrient pollution and enabling fertiliser recovery, it also confronts established social norms and perceptions. Human excreta are still widely associated with risk, contamination, and discomfort, which contributes to persistent socio-cultural barriers.
At the same time, broader environmental attitudes across Europe are generally favourable towards sustainability transitions. This creates a context in which acceptance is conditional rather than absent, shaped by how technologies are introduced, communicated, and experienced.
Empirical Insights from User Studies
Empirical investigations on the social acceptability1 of source-separating sanitation systems in the Paris Region provide valuable insights into user acceptance in practice. Surveys conducted between 2016 and 2024 across diverse contexts, including festivals, university campuses, semi-public spaces, and residential projects, show that users generally respond positively when certain conditions are met.
Key enabling factors include:
• Design continuity, where systems resemble conventional toilets
• Ease of use, minimising behavioural adjustments
• Cleanliness and maintenance, ensuring a reliable user experience
• Perceived environmental benefit, reinforcing users’ values
In many cases, users reported satisfactory experiences without explicitly recognising the innovative nature of the systems. Technologies such as waterless urinals were widely accepted, and the reuse of urine as fertiliser was generally perceived as a positive and environmentally friendly practice. These findings highlight the importance of direct experience in reducing hesitation and shaping acceptance.
At the same time, results point to limited user understanding of broader sanitation systems and technical constraints, particularly in residential contexts where residents have to take part in the maintenance of the devices, indicating a need for clearer guidance and communication.
A key insight is the central role of maintenance as a determinant of acceptance. Well-structured and visible maintenance supports user trust and long-term acceptance, while unclear responsibilities and inadequate service provision can lead to dissatisfaction and even project failure. This underscores that maintenance is not only a technical issue, but also a socio-institutional factor.
Finally, case studies such as the Azurisi 2demonstrator show that acceptance develops over time through ongoing socio-technical processes, where implementation also functions as a learning, coordination, and awareness-raising process.
The Role of Operation and Maintenance
A key insight emerging from the Paris case studies is that acceptance is not determined solely at the point of introduction but evolves over time through everyday interaction. In this context, operation and maintenance are critical factors.
Systems that are clean, reliable, and well-managed tend to sustain positive user perceptions. Conversely, insufficient maintenance, unclear responsibilities, or operational failures can rapidly undermine acceptance, regardless of initial attitudes. This highlights that acceptance is closely linked to institutional and organisational capacity, rather than being purely an individual or behavioural issue.
Determinants of Societal Acceptance
At a broader level3, societal acceptance is influenced by a combination of psychological, social, and institutional factors. There are several key determinants:
- Risk perception: Concerns related to odour, environmental contamination, and health risks remain central barriers.
- Institutional trust: Confidence in institutions, operators, and regulatory frameworks significantly affects acceptance.
- Contextual factors: Local conditions, cultural norms, and previous exposure to similar practices shape attitudes.
- NIMBY dynamics: While general support for nutrient recycling may be high, resistance often emerges when facilities are located in close proximity to residential areas.
These findings are consistent with established theories of technology acceptance, which emphasise the role of perceived risks, benefits, and trust in influencing behavioural responses.
Addressing Knowledge Gaps and Enhancing Awareness
Across both deliverables, a consistent observation is the limited public understanding of sanitation systems and nutrient cycles. Many users are unfamiliar with the fate of wastewater or the potential for nutrient recovery, which can constrain informed acceptance.
To address this, targeted awareness-raising measures are essential. These include:
- Informational signage and user guidance
- Workshops and participatory activities
- Demonstration projects and pilot installations
In particular, P2GreeN’s work emphasises the effectiveness of field visits and direct exposure in reducing perceived risks and improving understanding. Such approaches help translate abstract concepts into tangible experiences, thereby strengthening acceptance.
Implications for Implementation and Scaling
The findings from P2GreeN suggest that enhancing acceptance requires a multi-dimensional approach that integrates technical, social, and institutional considerations. Key implications include:
- Designing systems that align with user expectations and everyday practices
- Ensuring high standards of cleanliness and operational reliability
- Building trust through transparent governance and credible actors
- Tailoring communication strategies to local contexts
- Providing opportunities for direct engagement and experience
Importantly, acceptance should not be treated as a static barrier but as a dynamic process that can be actively shaped through design, communication, and governance.
Conclusion
User and societal acceptance represent fundamental components of the transition towards circular nutrient systems. The evidence gathered within the P2GreeN project demonstrates that, under appropriate conditions, acceptance can be high—even for solutions that initially challenge established perceptions.
By addressing concerns related to risk, trust, and usability, and by strengthening awareness and institutional support, it is possible to foster a more favourable environment for the adoption of source-separating sanitation and nutrient recycling. In this sense, acceptance is not only a prerequisite for implementation but also a key lever for enabling systemic change towards sustainable and circular resource management.
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