About

In addition to heavy metals and other pollutants, contaminants of emerging concern (CECs), such as endocrine-disrupting compounds, pharmaceuticals and microplastics, are detected in urban runoff. Monitoring programmes, as part of the Water Framework Directive (WFD), that aim to mitigate diffuse pollution cover only a small subset of these contaminants, which limits the quality of available data. Regulations on CECs are therefore limited.

Current combined sewer networks (CSN) are designed to process only a portion of major storms overflow, and untreated sewage is discharged into water bodies. This problem is worsening with climate change effects and varying rainfall patterns. The alternative, separated sewer networks (SSN) collect wastewater and stormwater separately and discharge it directly into receiving waters, with no purification, which is a serious threat to the quality of this water.

Nature Based Solutions (NBS), previously known as sustainable urban drainage systems (SUDS) or blue-green infrastructure, can contribute effectively to stormwater management of the sewer networks by reducing the volume and flow rate of stormwater runoff (e.g green roofs, wetlands or swales). Latest research suggests that the implementation of hybrid green-blue-grey infrastructures combining reliability, resilience, and acceptability of traditional grey infrastructures with multi-functionality and green-blue infrastructures adaptability and socio-ecological sustainability can bring important synergies to obtain a wide range of additional co-benefits.