Review of remediation technologies for sediments contaminated by heavy metals

Purpose: Contamination of sediments with heavy metals (HMs) is a worldwide environmental issue, due to the negative ecological effects of HMs. Sediments are an important component of aquatic ecosystems, impacting the transformation and transfer of HMs in the environment. Thus, remediating sediments polluted by HMs is a crucial activity within the full aquatic ecosystem remediation process, and economical, effective, and environmentally friendly remediation techniques are urgently needed. Materials and methods: We reviewed the existing literature on sediment remediation techniques and developments in the fields of environmental science and engineering, attempting to provide a better understanding of the advances of remediation techniques and new research directions for sediments contaminated by HMs. Results and discussion: This review summarized remediation methods (e.g., physical–chemical strategies, biological strategies, and combined techniques) used to treat sediments contaminated with HMs. This included analyzing the mechanisms associated with biological remediation technologies and their combination with other methods. Then, the review summarized the factors influencing the selection of remediation methods and evaluated the prospects of new emerging remediation methods. Conclusions: Bioimmobilization techniques (e.g., phytostabilization and microorganism immobilization) have received increased attention because of their low remediation cost and environmental compatibility. Furthermore, particular attention has been paid to explore the role of sulfate-reducing bacteria in decreasing heavy metal mobility. The review provides a useful theoretical foundation and technology reference for the remediation of sediment polluted by HMs.