• • The LIFE BIODAPH2O project is assessing a tertiary treatment technology based on the filtering capacity of daphnias in the effluents from the Quart WWTP to improve the chemical and ecological quality of the Onyar River.

One characteristic of Mediterranean rivers is their seasonality, which is further accentuated due to climate change. In this regard, many rivers and streams are heavily impacted by effluents from wastewater treatment plants (WWTPs), and in some cases, this may be the only water flowing during dry seasons, especially in streams and creeks. Thus, WWTP effluents ensure the circulation of water in certain river stretches, supporting life that would otherwise not exist. Unfortunately, WWTP treatment is insufficient to eliminate many of the chemical and biological compounds that can be harmful to the environment. We are talking about compounds such as microplastics, pharmaceuticals, or PFAS, which have been shown to be harmful to aquatic ecosystems.

Within the framework of the LIFE BIODAPH2O project, the chemical and ecological quality of the Onyar River has been monitored as it passes through the towns of Quart and Girona for a year. The results have revealed a deterioration of water bodies after the Quart WWTP. The presence of microplastics or perfluorinated compounds has been identified, as well as pharmaceuticals or antibiotic resistance genes at the WWTP outlet.

UdG researcher Manuela Hidalgo notes that perfluorinated compounds such as PFBS or PFOA have been detected at the WWTP outlet. These substances are present in many everyday products such as non-stick coatings on kitchenware, waterproof clothing, or fast food packaging. Although at very low concentration levels, they are detected in the river, especially in areas closest to the wastewater treatment plant discharge point. On the other hand, IDAEA-CSIC researcher Víctor Matamoros comments that there are antibiotics and antibiotic resistance genes that increase in the river due to the discharge of treated wastewater, thus making the river a reservoir of antimicrobial resistance genes that must be considered due to their implications for human health. Likewise, suspended particles found in the river water increase, all worsening the quality of the water body, as noted by Jordi Colomer from UdG.

The deterioration of the river’s chemical quality consequently affects its ecological quality, as pointed out by Julio López-Doval from the BETA-Vic technological center. These impacts manifest with a decrease in the diversity of aquatic organisms, such as insect larvae, other small invertebrates, and algal groups. There is an increase in the number of pollution-resistant organisms, which take advantage of these impacts with the consequent disappearance of organisms representative of cleaner waters, unable to cope with the presence of pollution.

In this aspect, UdG professor and coordinator of the LIFE BIODAPH2O project, Victòria Salvadó, explains that wastewater from WWTPs discharged into Mediterranean rivers or streams requires additional treatment, which must also be sustainable and green. The BIODAPH2O project is evaluating a tertiary treatment or water refinement technology from the Quart WWTP effluent to improve the chemical and ecological quality of the Onyar River as it passes through the town of Girona. This technology is based on the filtering capacity of daphnias. The project’s idea is to extend this technology to other Mediterranean locations with similar conditions and, furthermore, to use this water for agriculture, generating local water resources. The BIODAPH system has also been implemented at the Antissa wastewater treatment plant on the island of Lesvos (Greece) and will allow the production of regenerated water for agricultural irrigation of an adjacent 7,000 m2 plot.

The LIFE BIODAPH2O project (LIFE21-ENV-CA-BIODAPH2O) is co-funded under the LIFE programme of the European Commission and is made up of the University of Girona (coordinators), Sorigué, IDAEA-CSIC, BETA Technology Centre and the Catalan Water Partnership (CWP) as Catalan partners, and MINAVRA Techniki and the National Technical University of Athens (NTUA) as Greek partners.

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