Phosphate removal by mineral-based sorbents used in filters for small-scale wastewater treatment

Abstract

The mineral-based sorbents Filtra P, Polonite ® , natural wollastonite and water-cooled blast furnace slag (WCBFS) were studied in terms of their PO 4 removal performance. Results from a long-term column experiment showed that both Filtra P and Polonite ® removed > 95 % of PO 4 from the applied synthetic solution, and that the used filter materials had accumulated several (1.9-19) g kg -1 P. Phosphorus was removed also by natural wollastonite and WCBFS, but these materials were less efficient. Batch experiments on the used materials showed that the solubility PO 4 was considerably larger than the one expected for crystalline Ca phosphates such as hydroxyapatite, and results from investigations with attenuated total reflectanceFourier-Transform infrared spectroscopy (ATR-FTIR) on the Filtra P material showed that the formed P phase was not crystalline. These evidence suggest that a soluble amorphous tricalcium phosphate (ATCP) was formed in the mineral-based sorbents; the apparent solubility constant on dissolution was estimated to log K s = -27.94 (±0.31) at 21 o C. However, since only up to 18 % of the accumulated PO 4 was readily dissolved in the experiments it cannot be excluded that part of the phosphorus had crystallized to slightly less soluble phases.In conclusion, Filtra P and Polonite are two promising mineral-based sorbents for phosphorus removal, and at least part of the accumulated phosphorus is present in a soluble form, readily available to plants.

The Use of Blast Furnace Slag for Removal of Phosphorus from Wastewater in Sweden—A Review

“…At the end of the experiment, no signs of break-through (e.g., when the concentration in the influent is equal to the concentration in the effluent) could be detected and Johansson concluded that the slag materials were not saturated (Table 3). Gustafsson et al [25] reported an average P-removal of 86%, while there were hardly any differences between columns fed with P-solution or columns fed with real-life wastewater in the experiment carried out by Nehrenheim et al [18]. The results reported by Renman et al [27] also varied.…”

“…The aim of the study was to investigate the long-time performance of P-removal by two different BFS materials. Following these experiments, Gustafsson et al [25] evaluated the performance of BFS and several other materials, e.g., Filtra P, Polonite® and natural wollastonite with regard to P-removal using a column system also fed with a laboratory made P solution, containing 5 mg P/L. Column experiments using real-life wastewater have also been carried out by others; see for instance [26,27].…”

Removal of phosphate from water by a Fe–Mn binary oxide adsorbent

“…Another attractive feature of this technique is that the nutrient-loaded filters can be used in agriculture as phosphate fertilizer and soil conditioner [10]. A large number of materials from natural minerals to synthetic ones have been used as adsorbents to adsorb phosphate from wastewater [11][12][13][14][15]. Recently, the application of low cost and easily available materials for phosphate removal has been widely investigated, such as fly ash [16][17][18], blast furnace slag [19][20][21], iron oxide tailing [22], red mud [23,24], Ca-based adsorbents, and iron-based compounds [25][26][27].…”

Lab-Scale Column Study on Phosphorus Removal from Synthetic Wastewater by Filtralite P and Iron Filings

“…While as the distance from the inlet increases, the accumulated amount of phosphorus slightly decreases. Renman (2008) [18] and Gustafsson et al (2008) [9] investigated phosphorus removal potential of various filter materials (blast furnace slag, opoka, Polonite, limestone, wollastonite, Filtra P) in vertical columns and also came to a conclusion that phosphorus is mostly removed in the top layer of the substrate. Whereas in real wastewater treatment systems distribution of phosphorus sorbed in filter material may vary.…”

“…The alternative way of phosphorus removal is to use materials which compose of elements that could bind phosphorus. The scientists have investigated phosphorus removal by using various materials such as sand, crushed marble, vermiculite, calcite, limestone, alunite, shellsand, Filtralite P, Polonite, Nordkalk Filtra P, wollastonite, alum, blast furnace slag, electric arc furnace slag, ochre, iron filings [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. These materials are divided into three groups: natural materials, industrial by-products and man-made sorbents [1,[21][22][23].…”