Division of Land and Water Resources Engineering, KTH (Royal Institute of Technology), Teknikringen 76, 100 44, Stockholm, Sweden.
Department of Soil and Environment, Swedish University of Agricultural Sciences, Box 7014, 750 07, Uppsala, Sweden.
Environ Sci Pollut Res Int. 2018 Mar;25(8):7391-7400. doi: 10.1007/s11356-017-0925-y. Epub 2017 Dec 26.
The phosphorus (P) removal of five combinations of dual filters consisting of blast furnace slag (BFS), argon oxygen decarburisation slag (AOD) and electric arc furnace slag (EAF) was evaluated in column experiments with domestic waste water. The columns were fed with waste water for 24 days. The column with only EAF had the best P removal performance (above 93% throughout the experiment). The speciation of the bound P was evaluated by P K-edge X-ray absorption near-edge structure (XANES) spectroscopy. In all five columns, the main P species of the slag packed in the outlet chamber was amorphous calcium phosphate (ACP). In samples from the inlet chambers, the contributions from crystalline Ca phosphates, P adsorbed on gibbsite and P adsorbed on ferrihydrite were usually much greater, suggesting a shift of P removal mechanism as the waste water travelled from the inlet to the outlet. The results provide strong evidence that P was predominantly removed by the slags through the formation of ACP. However, as the pH decreased with time due to the progressively lower dissolution of alkaline silicate minerals from the slag, the ACP was rendered unstable and hence redissolved, changing the P speciation. It is suggested that this process strongly affected the lifespan of the slag filters. Of the slags examined, EAF slag had the best P removal characteristics and BFS the worst, which probably reflected different dissolution rates of alkaline silicates in the slags.
采用国内污水进行柱状实验，评估了由高炉渣（BFS）、氩氧脱碳渣（AOD）和电弧炉渣（EAF）组成的五种双滤料组合的除磷效果。这些柱状物用污水进料 24 天。仅含 EAF 的柱状物具有最好的除磷性能（整个实验过程中均高于 93%）。通过磷 K 边 X 射线吸收近边结构（XANES）光谱评估结合磷的形态。在所有五个柱状物中，出口室内填充的炉渣中主要的磷形态是无定形磷酸钙（ACP）。在入口室的样品中，通常来自结晶 Ca 磷酸盐、在水铝石上吸附的磷和在水铁矿上吸附的磷的贡献要大得多，这表明随着污水从入口移动到出口，除磷机制发生了转变。结果提供了有力的证据，表明磷主要是通过形成 ACP 被炉渣去除的。然而，由于碱性硅酸盐矿物从炉渣中逐渐溶解导致 pH 值随时间降低，ACP 变得不稳定并因此重新溶解，改变了磷的形态。据推测，这个过程强烈影响了炉渣过滤器的寿命。在所检查的炉渣中，EAF 炉渣具有最好的除磷特性，BFS 炉渣最差，这可能反映了炉渣中碱性硅酸盐的不同溶解速率。
