Combining sediment remediation and energy production for a better environment

Is it possible to combine sediment remediation and energy production for a better environment? The RemErgy project aims to make better use of our resources by combining dredging for remediation purposes with energy production, which would have positive effects on both the economy and the environment.

Contaminated fiberbanks can have a negative impact on the aquatic and atmospheric environment, through dispersal of environmental toxins and greenhouse gases. Therefore, it is important to find sustainable remediation methods for fiberbanks. In the past, the paper and pulp industry released large amounts of wood fibers into the aquatic environment. Today, the fiber material is found as large accumulations on the seafloor (so-called fiberbanks) in lakes and coastal areas in Sweden. Although fiberbanks are often contaminated with environmental toxins, only a few have been remediated in Sweden. One reason is that it is difficult to use conventional remediation methods for this unique type of sediment. Greenhouse gas formation and gas release in fiberbanks are high, which limits the possibility of using in-situ remediation methods.

The RemErgy project is therefore investigating the possibility of using dredged fiberbank material in biogas plants. The hypothesis is that treatment in the biogas reactor would not only generate energy but could also provide increased degradation of environmental toxins and thereby potentially lead to lower pollution levels, reduced sediment volume, while limiting uncontrolled emissions of greenhouse gases if the material is placed in landfill. Biogas production from fiberbanks has proven possible, but several aspects still need to be improved, especially the efficiency of anaerobic digestion and the degradation of environmental toxins.

The project investigates the methane production of three different types of fibrous sediments (with different fiber composition) when treated in small-scale biogas reactors together with or without different co-substrates (i.e. manure, sludge and food waste) at different temperatures. The measurements also include chemical analyses of persistent organic pollutants and metals, as well as in-depth characterization of the fibrous material before and after treatment.

In addition to the project members, the project has a broad reference group consisting of authorities and industry to promote anchoring and dissemination of results.