Global population growth, climate change, and increasing demand for animal-based protein are placing unprecedented pressure on food systems, highlighting the need for more sustainable and resource-efficient production models (Aiking & de Boer, 2020; Webb et al., 2020; Monika Zurek et. al., 2022). In this context, aquaculture is expected to play a key role in sustaining future protein supply (B��n�� et al., 2015; FAO, 2024), yet its environmental sustainability performance varies significantly across production systems (Garlock et al., 2024). Among emerging solutions, aquaponic systems offer a more sustainable approach by integrating fish and plant production while efficiently reusing water and nutrients (Goddek et al., 2019; Horn et al., 2023).
More recently, the integration of treated wastewater (TWW) into such systems has been proposed as an additional step towards more resource-efficient circularity circularity, with potential to further reduce freshwater use and recover valuable nutrients (Cifuentes-Torres et al., 2021). These systems operate within a tightly interconnected human–animal–environment nexus, where water quality, animal welfare, environmental integrity, and food safety are simultaneously intertwined. However, despite its positive environmental potential, this approach remains constrained by regulatory uncertainty, technical concerns, and, most importantly, limited societal acceptance (Christou et al., 2024; WHO, 2004). Whereas the technical aspects of treated wastewater utilization have been extensively investigated, the main research gap lies in the limited exploration of consumer perceptions regarding fish cultivated in treated wastewater based aquaponic systems (Drechsel et al., 2022). To close this gap, this study investigates German and Italian consumers' perceptions of fish produced in treated wastewater-based aquaponic systems.
Methodology
A combination of a systematic literature review and an online panel survey was applied to examine how concern, perceived benefits, and acceptance-enhancing measures shape consumers willingness to consume fish produced in this system, and how these perceptions relate to the human–animal–environment nexus. The construction of the perception dimensions were informed by the Health Belief Model. The online panel survey targeted only fish consumers through stratified sampling by gender, age, and region of residence both in Germany and Italy, and resulted in 1516 participants.
Exploratory factor analysis using Principal Component Analysis with Varimax rotation was conducted to identify and refine the underlying structure of the perception constructs, with internal consistency assessed prior to extracting factor scores. The dependent variable measured consumers' willingness to consume fish from treated wastewater based aquaponic systems on a six-point scale. After initial attempts with ordinal logistic regression proved unsatisfactory due to category overlap and violations of the proportional odds assumption, most notably in the German sample (��2 (3) = 14.755, p = .002), multinomial logistic regression was adopted, with perception dimensions used as predictors to assess their influence on consumers' acceptance, uncertainty, or rejection. A Pearson correlation analysis was also conducted to explore associations between perception dimensions and the components of the human, animal, and environmental nexus.
Discussion and Conclusion
Results revealed a general lack of in-depth knowledge of the use of treated wastewater in fish production, with approximately 50% of respondents in both countries (Italy: 52.2%; Germany: 49.7%) having only heard of the concept and not been able to describe it. Exploratory Factor Analysis identified three core perceptual dimensions shaping consumer attitudes: "Concern" (human-centered risk perception), "Perceived Benefits" (environmental and system-level evaluation), and "Acceptance-Enhancing Measures" (trust and governance). Multinomial Logistic Regression analysis showed that "Concern" was the most significant predictor of rejection in both nations.
In Italy, a high level of concern increased the likelihood of belonging to the rejection group by 5.11 times, whereas in Germany, it increased the odds by 3.27 times. Conversely, "Perceived Benefits" served as the primary driver for acceptance, increasing the likelihood of acceptance by 4.92 times in Italy and 3.72 times in Germany. Furthermore, "Acceptance-Enhancing Measures" such as transparency, independent checks, and labeling significantly reduced the likelihood of rejection in Germany (OR = 0.67), though they had a limited effect on active acceptance. Comparative results indicate that Italian consumers are more sensitive to both risk and benefit signals than German consumers, underscoring the need for culturally tailored communication strategies to promote TWW-based aquaculture.
When it comes to the interaction between perception dimensions and the human-animal-environment nexus, Pearson correlation analyses further demonstrated a holistic yet asymmetric relationship between consumer perception dimensions and the nexus. The "Concern" dimension showed a strong, statistically significant negative correlation with all three components in both countries (Italy: r = -0.682 to -0.590; Germany: r = -0.626 to -0.555; p < 0.01). This indicates that consumer risk perception is not localized but extends across the entire human-animal-environment nexus. Conversely, "Perceived Benefits" were positively and significantly correlated with all nexus components. In addition, Animal health, although integrated into the perception of risk, occupied a secondary position in consumer priorities compared to human and environmental impacts.
Overall, the study demonstrates that the social viability of the fish raised treated wastewater based aquaponic systems highly depends on how consumers cognitively and emotionally interpret the reuse of "human excreta" in food production. By integrating the human-animal-environment nexus into consumer research, this study contributes to a more comprehensive understanding of acceptance dynamics in circular food systems and provides actionable insights for policymakers, aquaculture practitioners, and system developers seeking to foster sustainable food system transitions.
Acknowledgment
This work is a part of EU Horizon Project "Aquaponics from WAstewater Reclamation (AWARE)". (Grant agreement ID: 101084245)
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