Removal of phosphorus using suspended reactive filters (SRFs) – efficiency and potential applications

The removal of phosphorus (P) from agricultural runoff is essential to reduce the threat of eutrophication in bodies of water. In this study, an alternative method of applying P reactive materials (RMs) in the form of suspended reactive filters (SRFs) is presented. The SRF method enables P which has already entered a body of water to be caught. In this study, an autoclaved aerated concrete (AAC) was used as the SRFs. The experiment was carried out in a laboratory in a hydraulic block of 1 m in width and 2 m in length. Three curtains, consisting of eight suspended bags filled with the AAC, were used. The ratio of RM mass to water volume in the hydraulic block was 3:1 (g:dm³). The initial concentration of P amounted to 1.335 mg P-PO₄·dm⁻³. The results demonstrated the successive reduction of P in the water over the experiment duration and the number of cycles in which water passed through the system of curtains. SRFs filled with AAC decreased the level of P-PO₄ in the solution to 0.190 mg·dm⁻³. The highest removal efficiency (50% overall P reduction) was observed at the beginning of experiment, when the average unit sorption amounted to 0.192 mgP-PO₄·g⁻¹.