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Carbon-intensive binders such as cement are traditionally employed to stabilise peat. Few studies have investigated alternative materials such as biochar to improve peat stability while simultaneously sequestering carbon dioxide (CO2). This study explored biochar produced through pyrolysis of clean wood and leaves to stabilize peat from Tiller-Flotten, Norway. Unconfined compressive strength (UCS), water content and pH measurements on biochar, Portland composite cement (CEM II) and peat compositions and a sustainability assessment were conducted. It was found that biochar amendment increased strength and stiffness of peat and cement-stabilised peat. Biochar showed the potential to reduce the cement amount when stabilising peat while retaining geotechnical properties. Peat stabilised with 200 kg/m3 of biochar and 100 kg/m3 of cement exhibited comparable strength (63.3±4.2 kPa, n = 3) as samples with 200 kg/m3 of cement (63.2±1.3 kPa, n = 3), but with a negative carbon footprint. Adding biochar quantities greater than 27% of the cement quantities resulted in a climate-neutral stabilisation. At a carbon price of approximately 85 €/tonne, the biochar costs equalled the cement costs. The cement-only samples outperformed the ones with additional biochar in terms of shear strength/€, while future carbon prices increased the competitiveness of biochar amendments.

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Remediation activities in polluted sediments, such as dredging and capping, induce the risk of transporting polluted sediments into the water column. Turbidity surveillance is the common method for in situ environmental monitoring during such activities. However, at various stages of the remediation process, the turbidity may be caused by either clean or polluted materials. Here, the potential of using chemical sensors to discriminate between turbidity caused by clean and polluted sediments is evaluated. Dissolved oxygen (DO), turbidity and pH were measured in laboratory tests with suspensions of three different polluted sediments, as well as for two common clean capping materials. Additionally, turbidity, pH and DO were measured during dredging at one of the polluted sites. Whereas turbidity caused by clean materials did not affect pH or DO, there is an inverse linear relationship between DO and turbidity for two of the polluted sediments. Furthermore, for two of the sediments, pH is a strong indicator of sediment resuspension into the water column, with ΔpH>0.5 both in the lab and during dredging in the field. Hence, pH and/or DO surveillance is shown to be potential tools for in situ real-time monitoring of environmental risk during disturbances in polluted sediments.