Research progress of in situ covering materials for river polluted sediment and their applications

In situ covering technology is one of the important means to control sediment pollutants, and the selection and optimization of covering materials as the technical core is a research hotspot. The main principles of in situ covering technology for sediment pollutants was summarized, and the remediation mechanism and remediation efficiency of three commonly used covering materials, including calcium peroxide, zeolite and biochar, were introduced. In view of the shortcomings of single covering material, such as weak selectivity of target pollutants, secondary release of pollutants, too fast consumption rate of materials and short remediation period, the method of modifying with modifier or combined use of multiple covering materials was proposed, which could effectively prolong the treatment time of covering materials, avoid the release of pollutants after short-term inhibition, and improve the remediation efficiency of covering materials for sediment pollutants. The advantages and application prospects of covering material modification process and combined process of various covering materials in the remediation of contaminated sediment were reviewed. At the same time, the combination of various covering materials, the collection and reuse of covering materials and the reduction of ecological risk were put forward for further research.