Addressing the challenges of combined sewer overflows

• DOI: 10.1016/j.envpol.2023.123225
• Publication Date: 2023-12-25T13:27:58Z
• Authors: William Bernard P...; Reza Ahmadian; Max Munday; Owen Jones; Steve J. Ormerod; Isabelle Durance
• Keywords: Combined sewer; Scrutiny

Europe's ageing wastewater system often combines domestic sewage with surface runoff and industrial wastewaters. To reduce the associated risk of overloading treatment works during storms, to prevent backing-up into properties, Combined Sewer Overflows (CSOs) are designed networks release excess discharge rivers or coastal waters without treatment. In view growing regulatory scrutiny increasing public concern about their excessive frequencies potential impacts on environments people, there is a need better understand these allow prioritisation cost-effective solutions.We review: i) chemical, physical biological composition CSOs discharges; ii) spatio-temporal variations in quantity, quality load overflows spilling receiving waters; iii) ecosystems economies. Despite investigations illustrating frequency CSOs, data spill loading pollutants too few reach representative conclusions, particularly for emerging contaminants. Studies appraising also scarce, especially contexts where multiple stressors affecting waters. Given costs addressing problems, but likely long-term gains (e.g. economic stimulation as well improvements biodiversity, ecosystem services, health wellbeing), we highlight here bolster evidence gaps. We advocate no-regrets options alleviate CSO problems taking consideration costs, carbon neutrality, benefit community well-being. Besides pragmatic, risk-based investment by utilities local authorities modernise systems, include more systemic thinking, linking policy makers, consumers, regulators, shift from issues integrated catchment solutions aim reducing contributions drainage water consumption; broader societal responsibilities example through improved regulation, behavioural changes consumption disposal waste networks, greater cost-sharing use.