Characterization, remediation and valorization of contaminated sediments – a critical review

The constraints associated with the availability of huge amounts of natural resources for infrastructure and agricultural development calls for the reuse and recycling of anthropogenically created geomaterials, which is in line with the UN Sustainable Development Goals. In this context, valorization of dredged sediments (DS), obtained from water bodies such as rivers, lakes, oceans, etc., as a resource material is worth considering. Unfortunately, DS might be contaminated and exhibit a higher moisture-holding capacity due to higher organic matter and clay minerals/colloids. These attributes pose a serious question towards dumping of the DS in the deep sea (in the case of marine sediments), a practice which though prevails presently but endangers marine life. Hence, the way forward would be to characterize them holistically, followed by adequate treatment to make them ecologically synergetic before developing a strategy for their valorization. In this regard, many studies have been focused on the characterization and treatment of DS to make them environmentally safe manmade resource. With this in view, a critical synthesis of the published literature pertaining to the (i) characterization, (ii) treatment, remediation, and immobilization of contaminants, and (iii) utilization of DS has been conducted, and the salient findings are presented in this paper. Based on this study, it was observed that the DS acts as a sink for emerging contaminants for which no remediation strategies are available. Moreover, the study highlighted the lacuna in upscaling the existing treatment and stabilization techniques to field conditions while highlighting the concept of circular economy.