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 Sep 15;477:135259. doi: 10.1016/j.jhazmat.2024.135259. Epub 2024 Jul 18.
Struvite recovery from wastewater offers a sustainable phosphorus and nitrogen source, yet it harbors the challenge of variable antibiotic residues, notably oxytetracycline (OTC), increasing the ecological risk during subsequent use. Despite the need, mechanisms behind these residues and regulatory solutions remain obscure. We characterized OTC in recovered struvite and showed that increased dissolved organic matter (DOM) enhanced OTC accumulation, while PO suppressed it. NH modulated OTC levels through the saturation index (SI), with a rise in SI significantly reducing OTC content. Additionally, excess Mg formed complexes with OTC and DOM (humic acid, HA), leading to increased residue levels. Complexation was stronger at higher pH, whereas electrostatic interactions dominated at lower pH. The primary binding sites for antibiotics and DOM were Mg-OH and P-OH groups in struvite. OTC's dimethylamino, amide, and phenolic diketone groups primarily bound to struvite and DOM, with the carboxyl group of DOM serving as the main binding site. Mg complexation was the primary pathway for OTC transportation, whereas electrostatic attraction of PO dominated during growth. Controlling magnesium (Mg) dosage and adjusting pH were effective for reducing OTC in recovered products. Our findings provided insights into the intricate interactions between struvite and antibiotics, laying the groundwork for further minimizing antibiotic residues in recovered phosphorus products.
从废水中回收鸟粪石为提供了一种可持续的磷和氮源，但它存在抗生素残留（尤其是土霉素）变化的挑战，这在随后的使用中增加了生态风险。尽管有需求，但这些残留物的背后机制和监管解决方案仍然不清楚。我们对回收的鸟粪石中的土霉素进行了特征描述，结果表明，增加的溶解有机物（DOM）会促进土霉素的积累，而 PO 会抑制其积累。NH 通过饱和度指数（SI）调节土霉素的水平，SI 的升高会显著降低 OTC 含量。此外，过量的 Mg 与 OTC 和 DOM（腐殖酸，HA）形成复合物，导致残留水平升高。在较高的 pH 值下，络合作用更强，而在较低的 pH 值下，静电相互作用占主导地位。抗生素和 DOM 的主要结合位点是鸟粪石中的 Mg-OH 和 P-OH 基团。OTC 的二甲氨基、酰胺和酚二酮基团主要与鸟粪石和 DOM 结合，而 DOM 的羧基是主要的结合位点。Mg 络合是 OTC 迁移的主要途径，而 PO 的静电吸引在生长过程中占主导地位。控制镁（Mg）剂量和调整 pH 值是减少回收产品中土霉素的有效方法。我们的发现深入了解了鸟粪石和抗生素之间的复杂相互作用，为进一步减少回收磷产品中的抗生素残留奠定了基础。
