Application of oyster shells in the remediation of marine sediment

PurposeThe aim of this article is to review the usage of waste oyster shells for marine sediment remediation. Sediments act as sources and sinks of pollution, serving long-term risks to humans and ecosystems because they accumulate both inorganic and organic pollution. Likewise, oyster shells are generated as waste and pose socioeconomic and environmental issues due to insufficient technology to manage them. So it is important to understand how these oyster shells control sediment pollutants.Materials and methodsNumerous oysters are cultivated worldwide annually, and oyster shells are generated as waste from food industries. Because oyster shells are abundant and inexpensive, many researchers are focusing on their applications in sediment remediation. Oyster shells are processed by heat treatment for activation and applied as active materials in sediment remediation by sediment capping and mixing. Sediment treatment can be performed by on-site active material capping or by dredging and off-site sediment treatments.Results and discussionOyster shells have been reported as excellent materials for sediment remediation because they improve the pH and oxidation-reduction potential and reduce the concentrations of nitrogen, phosphate, hydrogen sulfide, and heavy metals in the sediment and water. Furthermore, the use of oyster shells has been shown to enhance the ecological conditions of benthic habitats and promote the proliferation of microbial diversity. Sediment treatment by onsite sediment capping with oyster shells is far better than offsite treatment because there is no need for dredging and mobilization of sediment, and it also reduces the resuspension of pollutants in the water column.ConclusionOyster shells are a natural solution for controlling marine pollutants. Based on a number of investigations, it has been shown that oyster shells have the ability to reduce pollution both physically via adsorption and chemically through precipitation and chemical transformations. This study provides extensive information on sediment nutrients, toxic substances, and heavy metal management.