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.
