Purpose

This work aimed to (i) investigate the effect of hydraulic retention time (HRT) on controlling the release of phosphorus from sediment and (ii) interpret the phosphorus migration and transformation mechanism in the Al-PHOSLOCK thin-layer capping system.

Methods

A 35-day laboratory dynamic simulation experiment was conducted by applying the Al-PHOSLOCK thin-layer capping to evaluate the effect of HRT on interrupting the release of phosphorus from contaminated sediments. The total phosphorus (TP), inorganic phosphorus (IP), organic phosphorus (OP), non-apatite inorganic phosphorus (NAIP), and apatite phosphorus (AP) were identified as different phosphorus species and analyzed during the experiment to further elucidate the migration and transformation of phosphorus.

Results and discussion

The release of phosphorus from contaminated sediment was successfully suppressed by the Al-PHOSLOCK capping layer with an efficiency of higher than 90%. The HRT exerted a dual role on phosphorus controlling: at low HRT, slight water flow facilitated phosphorus migrating out from sediment and diffusing to the overlying water; at high HRT, the migration of phosphorus from overlying water back to sediment was strengthened. It was demonstrated that the phosphorus release was effectively controlled by the Al-PHOSLOCK thin-layer capping under different HRT conditions (static, 0.5 d, 1.0 d, and 3.0 d). The mechanism of phosphorus migration and transformation in the Al-PHOSLOCK thin-layer capping system was elucidated, including three significant stages of physical interception, adsorption, and capture/hold/transform process.

Conclusion

This study verified the good capacity of the Al-PHOSLOCK capping system for controlling the release of sediment phosphorus under different HRT. Therefore, it was expected to be a promising approach in the handling of water eutrophication.

中文翻译：

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Al-PHOSLOCK 薄层覆盖控制沉积物中磷的释放：水力停留时间和磷迁移/转化机制的影响

目的

这项工作旨在 (i) 研究水力停留时间 (HRT) 对控制沉积物中磷释放的影响，以及 (ii) 解释 Al-PHOSLOCK 薄层覆盖系统中磷的迁移和转化机制。

方法

通过应用 Al-PHOSLOCK 薄层覆盖进行了为期 35 天的实验室动态模拟实验，以评估 HRT 对中断受污染沉积物磷释放的影响。总磷（TP）、无机磷（IP）、有机磷（OP）、非磷灰石无机磷（NAIP）和磷灰石磷（AP）被确定为不同的磷种类，并在实验过程中进行分析以进一步阐明迁移和磷的转化。

结果和讨论

Al-PHOSLOCK 覆盖层成功抑制了污染沉积物中磷的释放，效率高于 90%。HRT在控制磷方面起着双重作用：在低HRT时，少量的水流促使磷从沉积物中迁移出来并扩散到上覆的水中。在高 HRT 下，磷从上覆水体向沉积物的迁移得到加强。结果表明，在不同的 HRT 条件（静态、0.5 天、1.0 天和 3.0 天）下，Al-PHOSLOCK 薄层封盖可以有效控制磷的释放。阐明了Al-PHOSLOCK薄层封盖系统中磷的迁移和转化机理，包括物理拦截，吸附和捕获/保持/转化过程的三个重要阶段。

结论

本研究验证了 Al-PHOSLOCK 封盖系统在不同 HRT 下控制沉积物磷释放的良好能力。因此，在水富营养化的处理中，有望成为一种有前途的方法。