This year-long research analysed emerging risks in influent, effluent wastewaters and biosolids from six wastewater treatment plants in Spain's Valencian Region. Specifically, it focused on human enteric and respiratory viruses, bacterial and viral faecal contamination indicators, extended spectrum beta-lactamases-producing Escherichia coli and antibiotic resistance genes. Additionally, particles and microplastics in biosolid and wastewater samples were assessed. Human enteric viruses were prevalent in influent wastewater, with limited post-treatment reduction. Wastewater treatment effectively eliminated respiratory viruses, except for low levels of SARS-CoV-2 in effluent and biosolid samples, suggesting minimal public health risk. Antibiotic resistance genes and microplastics were persistently found in effluent and biosolids, thus indicating treatment inefficiencies and potential environmental dissemination. This multifaced research sheds light on diverse contaminants present after water reclamation, emphasizing the interconnectedness of human, animal, and environmental health in wastewater management. It underscores the need for a One Health approach to address the United Nations Sustainable Development Goals.

This research was supported by project the Lagoon project (PROMETEO/2021/044) and MCEC WATER (PID 2020 116789 RB C 42 AEI/FEDER, UE). IATA-CSIC is a Centre of Excellence Severo Ochoa (CEX2021- 001189-S MCIN/AEI / 10.13039/ 501100011033). IF (MS21-006) and SB are supported by a postdoctoral contract grant for the requalification of the Spanish university system from the Ministry of Universities of the Government of Spain, financed by the European Union (NextGeneration EU).IG-G is recipient of a predoctoral contract from the Generalitat Valenciana (ACIF/2021/181), EC-F is recipient of a postdoctoral contract from the MICINN Call 2018 (PRE2018-083753) and AP-C is recipient of the contract Juan de la Cierva – Incorporación (IJC2020-045382-I) which is financed by MCIN/AEI/10.13039/501100011033 and the European Union “NextGenerationEU/PRTR". The authors thank Andrea López de Mota, Arianna Pérez, Agustín Garrido Fernández, Mercedes Reyes Sanz, José Miguel Pedra Tellols, and Alcira Reyes Rovatti for their technical support

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