Waste materials assessment for phosphorus adsorption toward sustainable application in circular economy

Phosphorus is the main determinant of nutrient enrichment in the water bodies. Many resources including nutrients may be shortly exhausted, assuming current consumption. This scenario leads to growing interest in resources recovery and/or reuse, which together with sustainable energy consumption and waste reduction are the main courses of the circular economy. Usage of coagulants in wastewater treatment plants (WWTP) does not allow phosphorus to be recovered from the sludge. An alternative method with recovery potential is the application of adsorbents. Many adsorbents have been approved for P-removal, however some of them are expensive. Response to that issue may be the application of waste materials and byproducts often intended for disposal/utilization. The main objective was to assess the P-removal efficiency of the waste materials/byproducts for application in small WWTP and eco-technologies like treatment wetlands as replacement of commercial adsorbents and alternative for conventional (chemical) treatment for potential phosphorus recovery. The materials investigated were (1) an expensive man-made product, (2) a byproduct with a high content of calcium oxide, and (3) drinking water treatment residuals (DWTRs) as beds from filters used to remove iron. Research was conducted in non-flow condition with various initial concentrations. The highest efficiency was received for fine-grained byproduct (9.58 mg/g), for commercial adsorbent LMB - 9.11 mg/g. The DWTRs adsorption was oscillated around 4.5 mg/g. These results confirmed the possibility of applying waste materials and byproducts for P-removal according to the circular economy idea. Further research should include implications of waste materials application to determine P-recovery concept.