Water Research Center, Tsinghua Shenzhen International Graduate School, Tsinghua, Shenzhen 518055, China.
Water Research Center, Tsinghua Shenzhen International Graduate School, Tsinghua, Shenzhen 518055, China; School of Water Resources and Electric Power, Key Laboratory of Ecological Protection and High Quality Development in the Upper Yellow River, Key Laboratory of Water Ecological Remediation and Protection at Headwater Regions of Big Rivers, Ministry of Water Resources, Qinghai University, Xining, Qinghai, China; State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, Qinghai, China.
J Hazard Mater. 2024 Dec 5;480:136355. doi: 10.1016/j.jhazmat.2024.136355. Epub 2024 Oct 29.
Seawater, as an alternative magnesium (Mg) source, has the potential to improve the overall economic and environmental footprint of struvite production compared to the use of pure Mg salts. However, the presence of other ions in seawater may affect the migration of tetracyclines (TCs), commonly found in wastewater, potentially reducing the quality of the recovered product, and posing environmental risks. But these effect has not been illustrated before. This study investigated the impact of seawater on oxytetracycline (OTC) migration during struvite recovery from swine wastewater. Under varying pH levels and Mg/P molar ratios, the OTC content in recovered struvite was ranged from 19 to 103 μg/g, which was 6 to 43 μg/g when using MgCl as Mg source. The key factor influencing OTC content was identified as Ca in seawater. The co-precipitation of hydroxyapatite (HAP) and the incorporation of dissolved organic matter (DOM) were the primary reasons for increased OTC content. Interactions between Ca on HAP surfaces and the carbonyl oxygen of OTC, along with ternary complex formations involving Ca, DOM, and OTC, facilitated OTC migration through adsorption onto struvite. Notably, increasing the Mg/P molar ratio reduced OTC enrichment due to the competition between Ca and Mg. Density functional theory (DFT) calculations supported these interfacial interactions. These findings enhanced the understanding of antibiotic migration during phosphorus (P) recovery using seawater as alternative Mg source and suggested solutions for reducing P recovery contamination in the future.
海水作为一种替代镁 (Mg) 源，与使用纯 Mg 盐相比，有可能改善鸟粪石生产的整体经济和环境足迹。然而，海水中其他离子的存在可能会影响通常存在于废水中的四环素 (TCs) 的迁移，从而降低回收产物的质量，并带来环境风险。但这些影响以前并未得到说明。本研究调查了海水对猪废水中回收鸟粪石过程中氧四环素 (OTC) 迁移的影响。在不同的 pH 值和 Mg/P 摩尔比下，回收鸟粪石中的 OTC 含量范围为 19 至 103μg/g，而使用 MgCl 作为 Mg 源时则为 6 至 43μg/g。影响 OTC 含量的关键因素被确定为海水中的 Ca。羟基磷灰石 (HAP) 的共沉淀和溶解有机物 (DOM) 的掺入是 OTC 含量增加的主要原因。HAP 表面上 Ca 与 OTC 的羰基氧之间的相互作用，以及涉及 Ca、DOM 和 OTC 的三元配合物的形成，促进了 OTC 通过吸附到鸟粪石上的迁移。值得注意的是，随着 Mg/P 摩尔比的增加，由于 Ca 和 Mg 之间的竞争，OTC 富集减少。密度泛函理论 (DFT) 计算支持这些界面相互作用。这些发现提高了对使用海水作为替代 Mg 源回收磷 (P) 过程中抗生素迁移的理解，并为未来减少 P 回收污染提供了解决方案。
