Sediment Remediation Using Activated Carbon: Effects of Sorbent Particle Size and Resuspension on Sequestration of Metals and Organic Contaminants

Abstract

Thin‐layer capping using activated carbon has been described as a cost‐effective in situ sediment remediation method for organic contaminants. We compared the capping efficiency of powdered activated carbon (PAC) against granular activated carbon (GAC) using contaminated sediment from Oskarshamn harbor, Sweden. The effects of resuspension on contaminant retention and cap integrity were also studied. Intact sediment cores were collected from the outer harbor and brought to the laboratory. Three thin‐layer caps, consisting of PAC or GAC mixed with clay or clay only, were added to the sediment surface. Resuspension was created using a motor‐driven paddle to simulate propeller wash from ship traffic. Passive samplers were placed in the sediment and in the water column to measure the sediment‐to‐water release of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and metals. Our results show that a thin‐layer cap with PAC reduced sediment‐to‐water fluxes of PCBs by 57% under static conditions and 91% under resuspension. Thin‐layer capping with GAC was less effective than PAC but reduced fluxes of high–molecular weight PAHs. Thin‐layer capping with activated carbon was less effective at retaining metals, except for Cd, the release of which was significantly reduced by PAC. Resuspension generally decreased water concentrations of dissolved cationic metals, perhaps because of sorption to suspended sediment particles. Sediment resuspension in treatments without capping increased fluxes of PCBs with log octanol–water partitioning coefficient (KOW) > 7 and PAHs with log KOW of 5–6, but resuspension reduced PCB and PAH fluxes through the PAC thin‐layer cap. Overall, PAC performed better than GAC, but adverse effects on the benthic community and transport of PAC to nontarget areas are drawbacks that favor the use of GAC. Environ Toxicol Chem 2022;41:1096–1110. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Passive Sampling-Based versus Conventional-Based Metrics for Evaluating Remediation Efficacy at Contaminated Sediment Sites: A Review

“…They also observed highly significant correlations between PDMS uptake and lipid-normalized body burdens. Ramöet al 75 simulated resuspension of AC-amended thin layer caps (3 mm to 5 mm) in intact cores. SPMDs and DGTs were deployed for 60 days in the water columns (as infinite sinks), while equilibrium sampling PDMS fibers were deployed in the sediment.…”

Does Activated Carbon Used for Soil Remediation Impact Eisenia fetida?

“…Activated carbon has been shown to effectively remediate organic contaminants in water and sediments (Abel & Akkanen, 2019; Cho et al, 2007; Cornelissen et al, 2011; Ghosh et al, 2011; Payne et al, 2019; Rämö et al, 2022), and recent studies indicate that activated carbon is likely also effective in the remediation of soils (Fagervold et al, 2010; Harwood et al, 2022). Activated carbon has been effectively used in the remediation of heavy metals, dyes, crude oil components (Ani et al, 2020; Dias et al, 2007), and other highly toxic persistent organic pollutants (Harwood et al, 2022; Millward et al, 2005; Payne et al, 2019; Tomaszewski et al, 2008).…”

“…For 71% of all studies monitoring for weight changes following exposure to activated carbon, no effect on growth was observed (Janssen & Beckingham, 2013). The studies indicating a negative effect on growth varied based on the percentage of activated carbon, sediment type, and activated carbon particle size (Janssen & Beckingham, 2013; Nybom et al, 2015; Rämö et al, 2022).…”

“…Activated carbon amendments are also a promising method of remediation for soils and sediments contaminated with hydrophobic organic pollutants (Abel & Akkanen, 2019; Cho et al, 2007; Cornelissen et al, 2011; Fagervold et al, 2010; Ghosh et al, 2011; Harwood et al, 2022; Patmont et al, 2015; Payne et al, 2019; Rakowska et al, 2012; Rämo et al, 2022). In terrestrial habitats, activated carbon is most often applied directly to the surface of the soil and acts as a sink for organic contaminants (Hilber et al, 2009; Jonker & Smedes, 2000; Koelmans et al, 2006; Pignatello & Xing, 1995).…”