| Abstrakt: |
The biomass bottom ash (BBAS) from Roubaix and Lens (France) with different physical–chemical characteristics was used as reactive filters for phosphorus (P) removal. The principal objective of our study was to evaluate the P removal potential with the two BBAS, and batch tests were performed to determine the influence of several parameters including the origin and type of BBAS, particle size, chemical composition, initial P concentration, contact time and water quality (real wastewater, synthetic wastewater) on P removal performance. Then, a series of laboratory scale column tests were performed with real wastewater doped to 30 mg P/l during the 8 months of experiments. To determine the mechanisms of P removal by the two BBAS, a monitoring of pH, calcium concentration and P concentration was performed using a fraction collector. In addition, a series of physical–chemical analyses such as XRD, SEM–EDS and sequential extraction were performed before and after 8 months of filter operation. The maximum phosphorus removal capacity (PRC) of the real wastewater solutions (100 mg P/l) in batch ranged from 1.56 to 1.96 mg P/g after 7 days of contact for BBAL and BBAR, respectively. The maximum P removal capacities in the columns varied from 4.15 to 9.72 g P/kg material after 8 months of experimentation for BBAL and BBAR, respectively. The results of XRD, SEM–EDS, sequential extraction confirm that the main mechanism of P removal was through precipitation of Ca-P (as hydroxyapatite). The P removal performance of the real wastewater was mainly related to the particle size, specific surface area and CaO dissolution of each BBAS. However, the results show that wastewater treatment plants represent an important source of Ca2+ ions to further promote the precipitation of hydroxyapatite on the surface, resulting in increased P removal efficiency. [ABSTRACT FROM AUTHOR] |
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