Stabilization and solidification of metal and organotin contaminated sediment after electrochemical pretreatment

Abstract

Abstract Purpose Stabilization and solidification (S/S) is a technique that enhances the structural properties of the sediment and reduces contaminant mobility, enabling the utilization of dredged contaminated sediment. Further reduction of the contaminants before S/S is, however, desirable to minimize leaching. The metal and organotin content in sediment could be reduced by electrochemical treatment. This is the first study on how electrochemical pretreatment impacts the strength and leaching properties of stabilized sediments. Methods Sediment was sampled from a port and was treated by using electrolysis. The removal of metals and organotin was investigated. Both treated and non-treated sediment was stabilized to investigate how electrolysis and also how different salinity and concentrations of organic matter during the curing affected the S/S properties by doing compression tests and leching tests. Results The electrolysis resulted in a 22% reduction of tributyltin (TBT) and a 44% reduction of zinc in the sediment. The results showed that the electrolyzed stabilized samples passed the requirements for compression strength and had a reduced surface leaching of zinc. Curing in saline conditions was beneficial for strength development and reducing the leaching of TBT. Conclusion Electrolysis reduced the sediment’s TBT and metal content, and the results indicate that pretreatment before stabilization could be beneficial to reduce contaminant leaching and to recover metals from the sediment. This study highlights the importance of investigating if a specific stabilization recipe fulfills the strength and leaching criteria in water similar to the field condition to assure satisfying results once implemented in the field.