State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering; Shanghai Institute of Pollution Control and Ecological Security, Tongji University, Shanghai, 200092, China.
Environ Sci Pollut Res Int. 2019 Feb;26(5):4890-4900. doi: 10.1007/s11356-018-3899-5. Epub 2018 Dec 19.
A waste-struvite/diatomite compound (MAP@Dia) recovered from nutrient-rich wastewater treated by MgO-modified diatomite (MgO@Dia) was provided to immobilize lead in aqueous solution and contaminated soil. The mechanism and effectiveness of lead immobilization was investigated, and the pH leaching test and fixed-bed column experiments were carried out to assess the risk of MAP@Dia reuse for lead immobilization. The results showed that MAP@Dia were effective in immobilizing lead in aqueous solution with adsorption capacity of 832.47-946.50 mg/g. The main mechanism of Pb immobilization by MAP@Dia could be contributed by surface complexation and dissolution of struvite followed by precipitation of hydroxypyromorphite Pb(PO)(OH). Lead(II) concentration reduced from 269.61 to 78.26 mg/kg, and residual lead(II) increased to 53.14% in contaminated soil when the MAP@Dia application rate was 5%. The increased neutralization capacity (ANC) and lower lead extraction yields in pH leaching test in amended soil suggested 5 times of buffering capacity against potential acidic stresses and delayed triggering of "chemical time bombs." The results of column studies demonstrated that amendment with MAP@Dia could reduce the risk of lead and phosphorus (P) leaching. This study revealed that MAP@Dia could provide an effective solution for both P recycling and lead immobilization in contaminated soil.
一种从富营养化废水（经氧化镁改性的硅藻土处理）中回收的鸟粪石/硅藻土复合物（MAP@Dia）被提供用于固定水溶液和污染土壤中的铅。研究了固定铅的机制和效果，并进行了 pH 浸出试验和固定床柱试验，以评估 MAP@Dia 再用于固定铅的风险。结果表明，MAP@Dia 有效固定水溶液中的铅，吸附容量为 832.47-946.50mg/g。MAP@Dia 固定 Pb 的主要机制可能是通过表面络合和鸟粪石的溶解，随后沉淀羟磷铅矿 Pb(PO)(OH)。当 MAP@Dia 的应用率为 5%时，污染土壤中的 Pb(II)浓度从 269.61 降至 78.26mg/kg，残余 Pb(II)增加到 53.14%。改良土壤中 pH 浸出试验的中和能力增加（ANC）和较低的铅提取率表明，MAP@Dia 具有 5 倍的潜在酸性胁迫缓冲能力，并且延迟了“化学定时炸弹”的触发。柱研究的结果表明，用 MAP@Dia 改良可以降低铅和磷（P）浸出的风险。本研究表明，MAP@Dia 可为污染土壤中的 P 回收和铅固定提供有效解决方案。
