New framework prevents pollution urban water runoff

The completion of an innovative project to prevent and manage diffuse pollution from urban runoff is providing benefits to water utilities, policymakers and urban planners. D4Runoff, which commenced in September 2022, has created a framework for prevention and management of this type of under studied pollution through data-driven design of nature-based hybrid innovations. The project, a consortium of 13 partners from across Europe, assessed current and future risk scenarios.

Urban water runoff, exacerbated by our changing climate, is increasingly recognised as a critical environmental challenge, as the pollutants carried pose significant threats to ecosystems, human health, and water resources. The problem is further exacerbated by aging sewer systems that are not equipped to manage large volumes of stormwater, particularly during intense rainfall events. Another unfavourable factor is pollution at the molecular level, particularly Contaminants of Emerging Concern (CECs), such as microplastics, pharmaceuticals, and endocrine disruptors. These pollutants are difficult to detect and are often overlooked in traditional water management practices.

Research consortium

Funded with €3.3 million by the European Commission under the Horizon Europe Climate, Energy and Mobility programme, the three-and-a-half-year project was coordinated by Denmark´s VandCenter Syd. The consortium consisted of organisations from Denmark, Spain, Portugal, France, and Italy, with leading experts in innovative water management systems, healthy water environments, civil engineers, interdisciplinary scientists and AI specialists.

Management platform launched

The D4Runoff project created a multi-criteria methodology for the design of cost-effective mitigation hybrid solutions combining new and existing Nature Based Solutions and water infrastructures (i.e blue-green-grey solutions). And an AI-assisted management platform was created to support water management stakeholders (water utilities and public authorities) in the planning, operation and risk monitoring of the urban infrastructures for the design of effective strategies to cope and mitigate urban runoff events.

Research across Europe

The methods and tools developed in the project were implemented, tested and validated at three demonstration sites: Odense (Denmark), Santander (Spain) and Pontedera (Italy), covering different climate areas. Replicability was also assessed at five further sites. A major study investigated CECs in urban runoff collected in six European cities, Copenhagen, Odense, Santander, Pontedera, Riga, and Ljubljana. Carried out by researchers from the Jožef Stefan Institute, (Slovenia) and the University of Riga, Faculty of Medicine and Life Sciences (Latvia). They used advanced analytical techniques, applying both targeted and non-target chemical screening to identify substances present which posed environmental risks. This multi-method approach revealed a much wider chemical landscape than traditional monitoring.

Comprehensive screening of pollutants

The researchers collected samples from road surfaces and traffic areas; roofs; urban drainage systems; and combined sewer overflows. Each sample was analysed for a broad set of substances, including metals, pharmaceuticals, industrial chemicals, plastic-related compounds, and chemicals linked to vehicle wear. This comprehensive screening allowed researchers to identify both well-known pollutants and emerging contaminants that are not yet part of routine monitoring. Highly water soluble chemicals were captured by chromatography and mass spectrometry, while metals were measured with inductive coupled plasma mass spectrometry.

By analysing how chemicals correlate with each other, clusters were identified, pointing to their sources which included traffic emissions, wastewater-related substances, and general urban background inputs. Such information, the researchers noted, is invaluable in understanding where pollution in cities is coming from, and where interventions will be most effective.

Metals among the most common pollutants

Key findings were that metals are among the most common pollutants in urban runoff. Zinc, copper, and aluminium were detected frequently and in high concentrations. In several runoff samples, especially those collected near busy streets or combined sewer overflows, metal concentrations reached levels that may harm aquatic organisms. This suggests that traffic remains a major source of metal contamination in cities.

More research needed

The researchers stressed that certain substances require more detailed study, particularly benzothiazole-2-sulfonic acid and other emerging contaminants that are not yet regulated. Monitoring programmes should be expanded to cover these emerging pollutants the researchers said.

The overall D4Runoff project, which concluded in February, is continuing until June to finalise work and build initiatives with other research groups.