MEDISA Methodology for sizing wastewater systems

The increasingly rigorous quality control requirements that apply to the natural environment and its usage (swimming, shellfish farming and impact on ecosystems) mean that local authorities are now examining the impact of discharges from their wastewater systems.

Storing surplus volumes generated by rainfall to subsequently control the flow seems the most appropriate solution for managing hydraulic shocks and reducing discharges of untreated wastewater into the natural environment. To date, however, there is no global method for sizing these installations in compliance with regulatory targets (EU Water Framework Directive [WFD] and French decree dated 21st July 2015).

Realistic and effective sizing of such installations requires overall consideration of the wastewater system – receiving environment, rainfall, wastewater system, pollution and economic and spatial feasibility – and development of integrated analysis tools.

The MEDISA project is aimed at perfecting a multi-criteria method that takes account of regulatory, environmental, economic and societal factors to help local authorities determine realistic dimensions for installations so that the impact of discharges from the wastewater network into the natural environment may be minimised.

MEDISA will develop a computerised platform and decision-making tool for analysing and comparing the different simulations carried out in order to assist decision-makers with their choices.