Fertilizer potential of calcium-rich substrates used for phosphorus removal from wastewater

Phosphorus (P) in wastewater is an important source of pollution, but properly managed, it can become a resource. Reactive filter media with a high affinity for P are promising in reducing P from effluents allowing nutrient recycling. In this study, three calcium-rich substrates (Filtra P, Polonite, wollastonite) with ability to remove P from wastewater have been saturated with P and tested as potential fertilizers in a pot experiment. Polonite had a relatively higher P content than Filtra P and wollastonite after saturation. All three materials tended to improve the yield of barley compared with the control treatment. Polonite induced the highest yield per unit of amendment from all three materials due to its higher P content, which could be shown in a higher ammonium lactate (AL)-extractable P in soil after harvesting. The application of the substrates slightly increased soil pH and decreased the hydrolytic acidity.