Nature-based: new opportunities in soil remediation

Development of and experience with nature-based solutions – Nature-based: new opportunities in soil remediation

A summary of the original article in the Dutch paper ‘Bodem’ (nr. 1, February 2024).

Nature-based solutions (NBS) are a crucial element in making soil and groundwater remediation more sustainable. Considering the approximately 300,000 seriously contaminated sites yet to be remediated in Europe, the use of NBS will be indispensable and will have a positive impact. Some of these techniques have already proven their value over several decades. In recent years, significant investments have been made in new techniques, variations of existing NBS and combinations of NBS with conventional techniques.

In a general sense, NBS offer several advantages over conventional high-tech techniques, such as cost-effectiveness (limited maintenance, lower energy costs, cheaper materials, less waste), reduced environmental impact, opportunities for integration with other themes (climate mitigation, biodiversity, carbon storage), and resilience in remote locations.

(c)TauwNL: Artist impression Natural CatchTAUW (Interreg RESANAT)

Certainly, there are also some focus areas and limitations of NBS, such as larger spatial requirements, longer duration, adaptation to local climates, and fluctuation of efficiency over time. Nevertheless, the exploration of possibilities and deployment of NBS for contaminated soils and surface waters are increasing due to the growing global awareness of the need for sustainability in all our activities (UN SDGs and EU Green Deal). This is evidenced by initiatives such as the EU Soil Strategy 2030 and the international standard ISO 18504 for sustainable remediation.

NBS research and development are financially supported by the EU through programs such as Horizon Europe, Interreg, and LIFE. Examples of these projects involving TAUW include GREENER (2019-2023), RESANAT (2019-2022), POPWAT (2020-2023), and MIBIREM (2022-2027). Additionally, organizations like NICOLE (Network for Industrially Coordinated Sustainable Land Management in Europe), major private stakeholders, and some government agencies (including OVAM in Flanders) are encouraging the adoption of NBS.

(c)TauwNL: Situation constructed wetland as Wetland+TM in Hájek. (Source: LIFE POPWAT, Layman’s report)

NBS aim to utilize and support natural processes, materials, and energy to facilitate the degradation, immobilization, or capture of contaminants. The mechanisms for dealing with contaminants primarily include adsorption, precipitation, biological, chemical, and photochemical degradation, as well as geohydrological isolation. Also NBS consider:

• Utilizing the natural flow of (ground) water as a driving force for permeable reactive barriers and dispersion of admixtures.
• Using solar energy in the form of UV radiation for photochemical degradation, heat for increasing biodegradation, and electricity for driving control units/pumps or electrochemical processes.
• Harnessing wind for creating negative pressure for bioventing or using compressed air for biosparging.
• Incorporating inert organic materials such as biochar, plant fibers, or peat for adsorption.
• Employing bacteria and fungi for degradation or immobilization.
• Utilizing trees, reeds, and other plants for phytoextraction, phytostabilization, or geohydrological control.
• Leveraging atmospheric oxygen for chemical oxidation or aerobic biodegradation.
• Using alkaline materials for neutralizing acidic environments, metal precipitation, and biostimulation.

EU projects such as RESANAT, GREENER, and POPWAT, along with other initiatives, have yielded initial results. Promising new NBS approaches are expected to be implemented in practice within 3-5 years, given their positive impact on the dimensions of People, Planet, and Prosperity. It’s time to take them into consideration and give them the space they deserve!

Author: Tobias Praamstra,

Consultant Soil, Groundwater & Sustainability, TAUW