Division of Soil and Water Management, KU Leuven, Kasteelpark Arenberg 20, 3001, Leuven, Belgium.
Division of Soil and Water Management, KU Leuven, Kasteelpark Arenberg 20, 3001, Leuven, Belgium.
J Environ Manage. 2023 Jul 1;337:117728. doi: 10.1016/j.jenvman.2023.117728. Epub 2023 Mar 20.
Iron (Fe) rich by-products can be added to lake or river sediments to immobilise phosphate (PO) and lower eutrophication risks. These Fe materials differ in mineralogy and specific surface area, hence differing in PO sorption capacity and stability under reducing conditions. This study was set up to identify key properties of these amendments in their capacity to immobilise PO in sediments. Eleven Fe rich by-products, collected from drinking water treatment plants and acid mine drainage, were characterised. The PO adsorption to these by-products was first determined under aerobic conditions and the solid-liquid distribution coefficient K for PO correlated strongly to oxalate extractable Fe content. A static sediment-water incubation test was subsequently used to evaluate the redox stability of these by-products. The reductive processes gradually released Fe to solution and more Fe was release from the amended than from the control sediments. The total Fe release to solution was positively related to ascorbate reducible Fe fractions in the by-products, suggesting that such fractions indicate potential loss of P retention capacity on the long term. The final PO concentration in the overlying water was 5.6 mg P L in the control and was successfully lowered by factor 30-420 depending on the by-product. The factor by which solution PO was reduced in Fe treatments increased with increasing K determined under aerobic conditions. This study suggests that efficient by-products to trap P in sediments are characterised by a high oxalate Fe content and a low reducible Fe fraction.
铁（Fe）丰富的副产品可以添加到湖泊或河流沉积物中，以固定磷酸盐（PO）并降低富营养化风险。这些 Fe 材料在矿物学和比表面积上存在差异，因此在还原条件下对 PO 的吸附能力和稳定性也不同。本研究旨在确定这些改良剂在固定沉积物中 PO 方面的关键特性。从饮用水处理厂和酸性矿山排水中收集了 11 种富铁副产品，并对其进行了表征。首先在有氧条件下确定了这些副产品对 PO 的吸附作用，并且 PO 的固液分配系数 K 与草酸盐可提取的 Fe 含量密切相关。随后使用静态沉积物-水孵育试验来评估这些副产品的氧化还原稳定性。还原过程逐渐将 Fe 释放到溶液中，并且从添加了这些副产品的沉积物中释放的 Fe 比从对照沉积物中释放的更多。溶液中总 Fe 的释放与副产品中抗坏血酸可还原 Fe 分数呈正相关，这表明这些分数表明从长期来看，潜在的 P 保留能力损失。在对照条件下，上层水中的最终 PO 浓度为 5.6mgPL，根据副产品的不同，成功降低了 30-420 倍。在 Fe 处理中，溶液 PO 降低的倍数随着在有氧条件下确定的 K 值的增加而增加。本研究表明，高效的副产品可通过高草酸盐 Fe 含量和低可还原 Fe 分数来固定沉积物中的 P。
