Retrofitting solution for increasing the resilience of urban wastewater infrastructures in heavy precipitation areas

PROJECT DESCRIPTION

BACKGROUND

Urban wastewater infrastructures are being affected by higher annual precipitation, especially in northern Europe, and the greater frequency of heavy precipitation events due to climate change. Models project an increase in annual precipitation over large parts of Europe (up to 30%) and an increase in heavy daily precipitations across most parts of Europe in winter by up to 35%. Rainwater that flows into combined sewer networks (CSN) is entering more quickly and at greater volumes into the wastewater infrastructures that are unable to treat the increased flows, leading to overflows at wastewater treatment plants with discharges of untreated sewage. These storm water overflows (SWOs) can have a significant environmental impact, accounting for a significant proportion of the contaminant load (BOD, N, P).

OBJECTIVES

LIFE RESEAU will develop and validate a novel solution for retrofitting and upgrading conventional activated sludge (CAS) wastewater treatment plants (WWTP) and combined sewer networks (CSN) to reduce by up to 100% the discharge of untreated stormwater overflows (SWOs) in heavy precipitation areas. The solution, which will be tested at the Moaña WWTO, in Galicia (Spain), and at the Søndersø WWTP in Denmark, aims to increase the resilience of urban wastewater infrastructures affected by total annual precipitation and heavy precipitation events caused by climate change. The novel solution is based on:

1. A highly efficient and flexible system of advanced biofilm reactor (ABR) that will be designed to be integrated into the existing activated sludge basins currently used in CAS systems, increasing the WWTP capacity (m3/h) by up to 600%, without additional land requirements, using the existing area and infrastructures (reactors intensification), while reducing the energy consumption and related CO₂ and N₂O emissions up to 66% and 85%.
2. A Storm Water Treatment Module (SWTM) based on mechanical filtration to be designed and integrated in the WWTP. The influents will be diverted to the reactors, storage tanks or the SWTM and distributed among them depending on their volumes and composition.
3. A Smart Infiltration/Inflow Management System (SiiMS) for monitoring and controlling the combined sewer networks.

The project addresses the following EU legislation:

• The Urban WW Treatment Directive
• The Adaptation EU Strategy
• The European Green Deal
• 2030 Climate Target Plan

RESULTS

Expected results:

• Reduction of up to 100% of untreated storm water overflows discharged by WWTP amounting to 36 000 m3 (30 000 m3 in Spain and 6 000 m3 in Denmark);
• Increase of up to 600% of the WWTP treatment capacity (m3/(m2*d));
• Compliance of water quality requirements for discharging and/or re-using wastewater: reduction of up to 95% of BOD load; reduction of up to 75% of the suspended solids, N, P and microplastic content in the Storm Water Treatment Module; and the removal of higher volumes emerging contaminants than existing in conventional activated sludge systems;
• Reduction in energy consumption of up to 66% amounting to 243 090 kWh (164,250 in Spain and 78 840 in Denmark);
• Reduction of up to 85% of N₂O emissions amounting to 894 kg of N₂O (657 in Spain and 237 in Denmark); and
• Reduction of up to 80% in CO2-eq emissions to 337 737 kg of CO2-eq