Trace element mobility in a polluted marine sediment after stabilisation with hydraulic binders

Abstract

The management of dredged marine sediment is an issue for many harbours, particularly when contaminant concentrations prevent disposal at sea. The stabilisation/solidification of the sediments with hydraulic binders for a use in road subgrade layer is a potential alternative solution. However, the environmental acceptability is not yet fully established. This paper presents the results of a case study to comprehensively determine the stabilisation of As, Cd, Cr, Cu, Ni, Pb and Zn. After demonstrating that stabilisation/solidification affects the microstructure of the sediment, a mobility study is realised (single, sequential and kinetic extractions). According to the regulatory/ technical guidelines the studied elements do not pose a risk to the environment. However, results from more complex mobility studies reveal that stabilisation in the short term is only effective for Ni while other elements are mobilised after treatment by at least one type of extraction. Stabilisation in the long term is not universally effective.

Effects of epoxy resin on ground-granulated blast furnace slag stabilized marine sediments

“…[5][6][7] Stabilization treatment can be used to enhance the environmental and mechanical properties of marine sediments utilizing lime, cement and other hydraulic binders. [8][9][10] Among various industrial waste materials, ground-granulated blast furnace slag (GGBS) is widely used in road construction, since their chemical and physical properties are similar, or even superior to traditional Portland cement. [11][12][13] However, environmental concerns about using of GGBS as soil stabilizer concentrated on the leachable quantities of hazardous elements, where chromium (Cr), barium (Ba), vanadium (V), molybdenum (Mo) have gained attention because of their toxicity on the environment and humans.…”

Effects of mineral amendments on trace elements leaching from pre-treated marine sediment after simulated rainfall events

“…The addition of gypsum did not improve As stabilization since the increase in competing anions due to gypsum dissolution could limit As adsorption on bauxite additive surface. As mobility has already been reported both at basic and acidic pH and this very specific behavior was attributed to the acid-base properties (amphoteric nature) of aqueous As (Saussaye et al, 2016;Tabelin et al, 2014).…”

“…Despite its direct presence in amendments, Cr is rapidly leached during the first days of experiment and a significant decrease in its concentration was observed after day 89. Saussaye et al (2016) noticed that in alkaline pH conditions, Cr mobility was limited in a larger extent. When 20% GBX was added, the pH of the media was slightly higher than for the other amendments.…”

Characterization of how contaminants arise in a dredged marine sediment and analysis of the effect of natural weathering

“…As the AP is lower than the NP, we can suppose that this sediment will not release acidic leachates. Even if this is the case, in order to prevent the dispersion of the contaminants by other possible mechanisms, a treatment and/or valorization could be envisaged, in civil engineering or the road-building domain, for example (Couvidat et al, 2016a;Saussaye et al, 2016;Bao et al, 2016).…”

“…Therefore, even though the sediments are strongly buffered, it is necessary to prevent all risk of leaching of the pollutants they contain by other mechanisms such as ORP modification, or by percolation of a chelating agent (Bäckström et al, 2004;Mayer et al, 2008). A treatment could be envisaged, even valorization, for example in a road building material, or in civil engineering by treatment with hydraulic binders (Paria and Yuet, 2006;Pinto et al, 2011;Wang et al, 2012;Couvidat et al, 2016a;Bao et al, 2016;Saussaye et al, 2016).…”