Sustainable urban drainage systems (SuDS), designed to manage stormwater runoff and reduce pressure on sewer systems, are facing a growing challenge: the buildup of pollutants within their soil. Now, a collaborative research effort is demonstrating a surprisingly effective, and decidedly low-tech, solution – combining the power of plants and worms to regenerate contaminated soils and extend the lifespan of these crucial urban infrastructures.
The project, led by the University of Strathclyde with partners Phyona Ltd and Pictish Worms, received a £15,000 proof-of-concept grant from the Industrial Biotechnology Innovation Centre (IBioIC) and the Hydro Nation Chair, building on a jointly led Crucible on the Circular Economy in October 2024. Researchers are finding that a biological approach can not only remove contaminants but also improve overall soil health, potentially transforming SuDS from systems requiring periodic, carbon-intensive cleanup to self-restoring ecosystems.
How Plants and Worms Work Together
Traditional SuDS mimic natural water flows, filtering out metals and organic pollutants from stormwater. However, these pollutants don’t simply disappear; they accumulate in the soil. Over time, this necessitates expensive and environmentally damaging excavation and disposal of the contaminated material. The Strathclyde team’s approach tackles this problem at its source, utilizing two key biological components.
The first is phytomining – the use of specific plant species capable of absorbing metals from the soil. This process, known as phytoextraction, effectively removes the contaminants, and offers the potential for metal recovery. The second component is the introduction of earthworms. These often-overlooked creatures play a vital role in breaking down organic pollutants and restoring the physical structure of the soil, improving its ability to function effectively.
Dr. Lorna Anguilano, reader at Brunel University and co-founder of Phyona Ltd, explained the core concept: “The goal was simple – to keep SuDS soils healthier for longer.” The research demonstrates that this isn’t merely a theoretical possibility. Early results have exceeded expectations, with successful contaminant removal and demonstrable improvements in soil health.
Beyond Remediation: Towards Self-Restoring Systems
The implications of this research extend beyond simply delaying the need for SuDS replacement. The team envisions a future where these drainage systems become actively regenerative, functioning as “living infrastructure.” This shift represents a significant departure from conventional approaches to urban drainage, which often treat soil as a passive filter rather than a dynamic ecosystem.
The low-impact and low-cost nature of the biological approach is a key advantage. Excavation and disposal of contaminated SuDS material is both expensive and generates a substantial carbon footprint. By keeping the soil healthy and functional for longer, this method offers a more sustainable and economically viable alternative.
The Broader Context of Nature-Based Solutions
This research aligns with a growing trend towards Nature-Based Solutions (NbSs) for urban challenges. As cities grapple with the increasing impacts of climate change, including more frequent and intense rainfall events, NbSs – particularly SuDS – are gaining recognition as valuable tools for enhancing water resilience, and sustainability. A recent systematic review published in MDPI highlights the potential of NbSs, but also points to the need for standardized and scalable methodologies for their implementation.
The Strathclyde project addresses this need by providing a concrete example of how biological systems can be integrated into existing SuDS infrastructure. The combination of phytomining plants and earthworms offers a practical and readily deployable solution for regenerating contaminated soils.
Challenges and Future Directions
While the initial results are promising, further research is needed to fully understand the long-term effectiveness of this approach. Factors such as the specific types of pollutants present, the composition of the soil, and the local climate will all influence the performance of the system. The research team will need to investigate the optimal plant and worm species for different environments and pollutant profiles.
scaling up this technology from proof-of-concept to widespread implementation will require careful consideration. Ensuring a reliable supply of appropriate plant and worm species, and developing efficient methods for their introduction into existing SuDS, will be crucial. However, the potential benefits – a greener, cheaper, and more resilient urban infrastructure – are significant enough to warrant continued investment and development.
The work represents a shift in thinking about urban infrastructure, moving away from purely engineered solutions towards systems that work *with* nature, rather than against it. As cities continue to grow and face increasing environmental pressures, this approach may become increasingly vital for creating sustainable and livable urban environments.
