Introduction
Increasing water scarcity, climate pressure, and competition between agricultural, industrial, and urban water uses are driving renewed interest in wastewater reuse as a sustainable water source for food production systems in Europe. Regulation (EU) 2020/741 on minimum requirements for water reuse establishes a harmonised framework to ensure that reclaimed water is fit for purpose, protects human and animal health, and safeguards the environment through a riskbased, multibarrier approach. Aquaponics systems require stable, highquality water to maintain fish welfare, plant productivity, and food safety Conventionally, these systems rely on drinking water, which offers welldefined and stable physicochemical and microbiological characteristics. In contrast, reclaimed municipal wastewater presents greater variability and potential risks, as standard urban wastewater treatment processes are not designed to meet aquaculturegrade requirements or to fully control pathogens, nutrients, and contaminants of emerging concern. This work focuses on bridging this gap by evaluating whether appropriately designed, integrated treatment trains can produce reclaimed water of quality comparable to tap water for aquaponic applications.
Materials and methods
An advanced tertiary treatment train developed by Aquasoil was applied to municipal wastewater to produce aquaponicsgrade reclaimed water. The MITO3X�� technology combines highefficiency ozonation with enhanced ozone mass transfer and radical formation, achieving nearinstantaneous contact times (<1 s) and optimised pollutant oxidation [1]. Ozonated effluent was subsequently treated by vacuum ultraviolet (VUV) irradiation at 185 nm to promote hydroxyl radical and hydrated electron generation for organic micropollutant degradation. A downstream bioreactive storage unit (15 m3), composed of granular activated carbon, expanded clay, and lava rock, provided adsorption and biological polishing with a 15 h empty bed contact time at 1 m3 h-1. Aquaponic trials were conducted in two replicated, smallscale closedloop recirculating aquaculture systems (RAS) supplied with reclaimed water and tapwater control. Each system consisted of three 350 L fish tanks stocked with 140���±���6 tilapia coupled to a DWC unit with 5 m2 of lettuce production. Physicochemical and biological parameters were monitored after advanced treatment and during aquaponic operation covering microplastics, metals, organic emerging micropollutants, fecal indicator bacteria, parasites (18S rRNA metabarcoding), and human enteric viruses (SaV, NoV GI/GII, HAV, HEV, crAssphage, PMMoV). Antibiotic resistance genes, class 1 integron gene (intI1) and bacterial community structure were characterised using 16S rRNA gene metabarcoding in water, biofilter rocks, fish and roots.
Results
After implementation of the multibarrier quaternary water treatment, water quality analyses showed that Escherichia coli and enterococci were consistently below the limits of detection (<LOD), PMMoV concentrations below the limit of quantification (<LOQ) and no pathogenic parasiteassociated reads detected in reclaimedwaterfed aquaponic systems. Metal concentrations remained below regulatory thresholds. Levels of total coliforms, organic emerging micropollutants, and microplastics were higher in the RAS compared to reclaimed wastewater influent. The intI1 gene used as a proxy for antimicrobial resistance (AMR), was mostly <LOQ or <LOD in water, biofilter, fish, and root samples across both experimental runs. No significant differences in either total bacterial abundance (16S rRNA gene) or intI1 levels were observed in fish or plant roots between reclaimed wastewater and tapwaterfed systems. Overall, aquaponic systems supplied with reclaimed water and tap water exhibited comparable trends across all monitored parameters. The study shows that aligning quaternary advanced treatment processes with aquaponic operational needs and EU reuse regulations enables the transformation of reclaimed wastewater into reliable input water source, supporting system performance and circular water management.
Acknowledgment
Horizon Europe project: Aquaponics from wastewater reclamation (AWARE) GA N. 101084245
References
[1] J. F. Mata de la Vega, K. N. Esfahani, T. Mao, P. Roccaro, B. Cantoni, D. Santoro, (2026). Advanced oxidation of tertiary wastewater micropollutants with nearly-zero contact time, Journal of Environmental Chemical Engineering,14 (1), 120691, https://doi.org/10.1016/j.jece.2025.120691