Recent studies demonstrated the practical potential of multiple beneficial reuse of ferric-rich drinking water sludge (ferric DWS) for sulfide and phosphate removal in wastewater applications. In practice, ferric DWS is often stored on-site for periods ranging from days to several weeks (or even months), which may affect its reuse potential through changes in iron speciation and morphology. In this study, we investigated for the first time the impact of ferric DWS ‘aging’ time on the iron speciation and morphology and its subsequent impact on its reactivity and overall sulfide and phosphate removal capacity. A series of coagulation tests were conducted to generate ferric DWS of a practically relevant composition by using raw influent water from a full-scale drinking water treatment plant (DWTP). A comparison with ferric DWS from 8 full-scale DWTPs confirmed the similitude. The presence of akaganeite (β-FeOOH) was detected in ferric DWS (through XRD analyses), independent of the DWS storage time. However, the morphology of akaganeite changed over time from a predominant poorly-crystalline phase in ‘fresh’ DWS (8 ± 0.1% of total Fe) to a highly crystalline phase (76 ± 3% of total Fe) at a sludge aging time of 30 days which was confirmed by means of Rietveld refinement in XRD analyses (n = 3). Subsequent batch tests showed that its sulfide removal capacity decreased significantly from 1.30 ± 0.02 mmol S/mmol Fe (day 1) to 0.60 ± 0.01 (day 30), a decrease of 54 % (p < 0.05). The level of crystallinity however had no impact on sulfide removal kinetics, most sulfide being removed within 10 minutes. Upon aeration of sulfide-loaded ferric DWS in activate sludge, amorphous iron oxides species were formed independent of the initial DWS crystallinity which resulted in efficient P removal at capacities similar to that of conventional FeCl₃ dosing.

最近的研究表明，富含铁的饮用水污泥（铁DWS）可以多种有益的再利用的实际潜力，用于废水中的硫化物和磷酸盐去除。在实践中，铁DWS通常在现场存储几天到几周（甚至几个月），这可能会通过铁形态和形态的变化影响其再利用潜力。在这项研究中，我们首次研究了铁DWS的“时效”时间对铁形态和形态的影响，以及随后对其铁活性和总硫化物和磷酸盐去除能力的影响。进行了一系列凝结试验，通过使用来自大型饮用水处理厂（DWTP）的原水来生产具有实际相关成分的三氧化二铁。与来自8个完整DWTP的铁DWS的比较证实了相似性。赤铁矿的存在（β -FeOOH）（通过XRD分析）在铁DWS中检测到，与DWS储存时间无关。然而，赤泥的形态随时间的变化从污泥老化时间为“新鲜”的DWS中的主要低结晶相（占总铁的8±0.1％）变为高度结晶相（占总铁的76±3％）。 30天，这是通过X射线衍射分析中的Rietveld精炼证实的（n = 3）。随后的批量测试表明，其硫化物去除能力从1.30±0.02 mmol S / mmol Fe（第1天）显着降低至0.60±0.01（第30天），降低了54％（p <0.05）。但是，结晶度对硫化物的去除动力学没有影响，大多数硫化物在10分钟内被去除。在活性污泥中载有硫化物的三氧化二铁曝气后，形成了无定形氧化铁物质，而与初始DWS的结晶度无关，这导致以与常规FeCl ₃定量给料相似的能力有效去除P。