Periodic Reporting for period 1 - NanoPhosTox (Nanocomposite Engineered Particles for Phosphorus Recovery and Toxicological Risk Assessment for the Aquatic Environment)
Berichtszeitraum: 2020-09-01 bis 2022-08-31
Technologically powerful materials for more efficient wastewater treatment are always in demand and important for society, especially in the rapidly changing modern world, seeking more sustainable, integrated and holistic water management solutions towards circular economy, resource recovery, water reuse, and enhanced protection of the aquatic ecosystems.
Wastewater treatment plants (WWTPs) offer a significant untapped potential for “urban mining” and secondary resource recovery (nutrients, energy, water, etc), although their priority task is, first and foremost, to treat safely and reliably the wastewater, complying with the regulatory discharge limit values.
The recently revised and newly adopted EU Urban Waste Water Treatment Directive (UWWTD 2024/3019) was approved by the European Council in November 2024. It sets new ambitious goals for WWTPs, incl. energy neutrality, advanced quaternary treatment for micropollutants removal (pharmaceuticals, cosmetics, microplastics, etc.), more stringent discharge limit values for the nutrients phosphorus (P) and nitrogen (N), and last but not least, P recovery from sewage sludge and wastewater with minimum P reuse and recycling targets to be defined by January 2028.
The new stricter discharge limit values for phosphorus go down to 0.5 mg/L total P for WWTPs >10 000 p.e. which is economically difficult to achieve with conventional treatment techniques. Alternatively, sorption is one of the most effective methods for the removal of dissolved compounds, especially in the low concentration range of µg/L-mg/L. As demonstrated in this project, with the help of engineered reusable nanocomposite adsorbents combining various 2-, 3- and 4-valent metals (Ca2+, Mg2+, Zn2+, Fe3+, Zr4+) co-precipitated as oxides/hydroxides in one material, it is possible to tackle simultaneously both goals in the new UWWTD, namely total P removal to ultra-low concentrations (
This project has 5 specific objectives, all successfully fulfilled in the implementation of the action, namely: 1) Synthesis of 10 nanostructured P-sorbent coatings for the modification of the magnetic particles; 2) Identifying the chemical composition, size and concentration range of the nanoparticles and soluble heavy metals likely to be leached from the sorbents and discharged in the aquatic environment; 3) Studying the potential hazards to aquatic organisms and possible toxicity mechanisms using ecotoxicological ISO- and OECD-standardized bioassays; 4) Toxicological risk assessment analysis and selection of the most efficient and "safe-by-design" P-sorbent; 5) Immobilizing the selected P-sorbent on magnetic carrier particles and verifying its ability to be regenerated and reused multiple times.
The overall project objective is to advance the commercialization and full-scale implementation of a highly promising technology for P removal and recovery from wastewater by verifying its environmentally friendly application, and the adsorbents' compliance with the “Safe-and-Sustainable-by-Design” principle.
Wastewater treatment plants (WWTPs) offer a significant untapped potential for “urban mining” and secondary resource recovery (nutrients, energy, water, etc), although their priority task is, first and foremost, to treat safely and reliably the wastewater, complying with the regulatory discharge limit values.
The recently revised and newly adopted EU Urban Waste Water Treatment Directive (UWWTD 2024/3019) was approved by the European Council in November 2024. It sets new ambitious goals for WWTPs, incl. energy neutrality, advanced quaternary treatment for micropollutants removal (pharmaceuticals, cosmetics, microplastics, etc.), more stringent discharge limit values for the nutrients phosphorus (P) and nitrogen (N), and last but not least, P recovery from sewage sludge and wastewater with minimum P reuse and recycling targets to be defined by January 2028.
The new stricter discharge limit values for phosphorus go down to 0.5 mg/L total P for WWTPs >10 000 p.e. which is economically difficult to achieve with conventional treatment techniques. Alternatively, sorption is one of the most effective methods for the removal of dissolved compounds, especially in the low concentration range of µg/L-mg/L. As demonstrated in this project, with the help of engineered reusable nanocomposite adsorbents combining various 2-, 3- and 4-valent metals (Ca2+, Mg2+, Zn2+, Fe3+, Zr4+) co-precipitated as oxides/hydroxides in one material, it is possible to tackle simultaneously both goals in the new UWWTD, namely total P removal to ultra-low concentrations (
This project has 5 specific objectives, all successfully fulfilled in the implementation of the action, namely: 1) Synthesis of 10 nanostructured P-sorbent coatings for the modification of the magnetic particles; 2) Identifying the chemical composition, size and concentration range of the nanoparticles and soluble heavy metals likely to be leached from the sorbents and discharged in the aquatic environment; 3) Studying the potential hazards to aquatic organisms and possible toxicity mechanisms using ecotoxicological ISO- and OECD-standardized bioassays; 4) Toxicological risk assessment analysis and selection of the most efficient and "safe-by-design" P-sorbent; 5) Immobilizing the selected P-sorbent on magnetic carrier particles and verifying its ability to be regenerated and reused multiple times.
The overall project objective is to advance the commercialization and full-scale implementation of a highly promising technology for P removal and recovery from wastewater by verifying its environmentally friendly application, and the adsorbents' compliance with the “Safe-and-Sustainable-by-Design” principle.
In this project, 11 different nanocomposite adsorbents were synthesized, characterized and their stability was investigated under different physiochemical conditions, incl. solubility of Zn2+ ions or leaching of potentially hazardous nanoparticles. In the first phase, a coarse ecotoxicological screening was performed, showing that only the Zn-containing materials had acute bioluminescence inhibition effects and were classified as harmful (30-min EC50<100 mg/L) to bacteria Vibrio fischeri - a model organism in the ISO-standardized acute toxicity bioassay ISO-21338 for rapid and cost-effective high-throughput screening of chemicals. Furthermore, measures were taken to optimize the adsorbent particles’ structure by reducing the amount of incorporated Zn2+ to minimize the leaching of hazardous heavy metals in the treated effluent. The presence of zinc, however, is necessary to enhance the adsorption selectivity towards phosphate.
In the second project phase, the environmental hazard assessment of the proposed novel adsorbents was advanced further by investigating their toxicity effects on other model organisms from different trophic levels of the aquatic food-web. Two additional OECD-standardized bioassays were performed: 48-h acute immobilization test with crustacean Daphnia magna (OECD 202) and 72-h algal growth inhibition assay with green freshwater microalgae Raphidocelis subcapitata (OECD 201). The latter is especially relevant due to the role of algae as primary producers in the aquatic environment and their short lifespan, which facilitates rapid detection of adverse effects over several generations in just 72 h. The results confirmed that all Zn-containing adsorbents were indisputably toxic to D. magna (1
The project results were published in 2 peer-reviewed articles (Journal of Cleaner Production: https://doi.org/10.1016/j.jclepro.2024.141287(öffnet in neuem Fenster); Water Science & Tecchnology: https://doi.org/10.2166/wst.2021.026(öffnet in neuem Fenster)) presented at 3 international conferences (E-MRS 2023 Spring Meeting, Strasbourg, Fance; EcoBalt 2023, Tallinn, Estonia; IWA LET 2024, Essen, Germany) and 2 MSc theses were supervised within the project framework. Currently, 1 more manuscript for peer-review is in preparation.
In the second project phase, the environmental hazard assessment of the proposed novel adsorbents was advanced further by investigating their toxicity effects on other model organisms from different trophic levels of the aquatic food-web. Two additional OECD-standardized bioassays were performed: 48-h acute immobilization test with crustacean Daphnia magna (OECD 202) and 72-h algal growth inhibition assay with green freshwater microalgae Raphidocelis subcapitata (OECD 201). The latter is especially relevant due to the role of algae as primary producers in the aquatic environment and their short lifespan, which facilitates rapid detection of adverse effects over several generations in just 72 h. The results confirmed that all Zn-containing adsorbents were indisputably toxic to D. magna (1
The project results were published in 2 peer-reviewed articles (Journal of Cleaner Production: https://doi.org/10.1016/j.jclepro.2024.141287(öffnet in neuem Fenster); Water Science & Tecchnology: https://doi.org/10.2166/wst.2021.026(öffnet in neuem Fenster)) presented at 3 international conferences (E-MRS 2023 Spring Meeting, Strasbourg, Fance; EcoBalt 2023, Tallinn, Estonia; IWA LET 2024, Essen, Germany) and 2 MSc theses were supervised within the project framework. Currently, 1 more manuscript for peer-review is in preparation.
The application of safe-by-design advanced materials and novel water treatment solutions is important and benefits whole communities, ecosystems and society-at-large by protecting our natural water bodies from eutrophication, preserving freshwater sources, securing clean water and alternative safe water supply through water reuse in water-stressed areas. Furthermore, such technologically powerful materials provide the opportunity not only to purify wastewater more efficiently by achieving higher effluent quality, but also to recover valuable nutrients from it, such as phosphorus (P), which is a fundamental building block of life and irreplaceable element for the growth of organisms, but at the same time a non-renewable finite resource and a key nutrient with crucial importance for agriculture and global food security.