Rational Selection of Tailored Amendment Mixtures and Composites for In Situ Remediation of Contaminated Sediments

Abstract

Emerging laboratory-scale research by our group and others has shown that contaminant transport pathways and bioavailability can be interrupted in-situ by modifying and enhancing the contaminant assimilation capacity of natural sediments. This is achieved by adding amendments such as activated carbon for binding persistent organic pollutants and natural minerals such as apatites, zeolites, or bauxite for the binding of toxic metals in sediments. This research was focused on advancing in-situ remediation of contaminated sediments by comparing different sorbents, either alone or in formulated combinations of new amendments, improving scientific understanding of how multiple amendments function together and reduce contaminant bioavailability, and developing efficient delivery methods for applying amendments to impacted sediments. Results presented in this report indicate that with suitable combination of sorbents, sorption of metals and organics can take place simultaneously. A primary list of 75 potential sediment amendments were identified from those currently under development for remediation of individual sediment contaminants and from existing industrial sorbents used for water- and gasphase treatments. Initial screening was based on literature information on sorptive/degradative capacity, potential ecological effects in the sediment environment, and potential complications during deployment such as material density, erodability, decay or transformation in freshwater and saltwater environments. The screening produced a list of eleven sorbents that were used for further sorption testing of metals and organics.