The fight against micropollutants in urban water: an innovative research project in Bordeaux

By Marion-Justine Capdeville, Environment Project Manager, Le LyRE - SUEZ Water France
The presence of micropollutants produced by human activity (pharmaceuticals, cosmetic or phytosanitary products, insecticides, etc.) in aquatic ecosystems is a complex environmental problem. REGARD (reduction and control of micropollutants in Bordeaux Metropole) is a partnership-based project that adopts a global approach to study and reduce these substances throughout the Bordeaux conurbation.


Launched in March 2015, this project was one of the 13 prize-winners of the nationwide call for projects “Combating micropollutants in urban water with innovation and new practices”. Nine partners* with diverse and complementary skill sets worked together for four years to identify and quantify the flows of micropollutants in wastewater, rainwater and the natural environment, to understand their impacts and to propose solutions to combat these forms of pollution.

The first step of the project consisted of studying rainwater from diverse sources, wastewater from industry, hospitals and households, the water and sludge in wastewater treatment plants and, finally, river water, in order to list the different types of micropollutants present in the urban community. The study revealed that paracetamol is the most widely found molecule in untreated wastewater. The wastewater also contained other molecules from over-the-counter medicines, such as anti-inflammatory drugs, but also pesticides, coming for example from anti-flea products, biocides used in paint and building materials, or the AMPA produced by the degradation of glyphosate and phosphonates.  Some of these molecules are effectively eliminated by wastewater treatment plants, while others are not, and are regularly discharged in infinitely small quantities into the natural environment.  This chemical characterisation was supplemented by biological tests to assess the effects of these micropollutants. Ultimately, these studies resulted in a list of about 20 micropollutants that represent an issue for Bordeaux Metropole.

This first phase also included a societal operation, consisting of interviews, sociological studies and an online survey of local residents in order to better understand their habits, practices and the products at the source of the emissions of micropollutants.

The second phase of the project focused on identifying solutions, and in particular preventive solutions that reduce this pollution at the source. Around 40 families volunteered to try and change their habits, for example by reducing the diversity of the household products they use, or by preferring more natural products, such as sodium bicarbonate, black soap or white vinegar.

The two sources of micropollutants examined in hospitals were pharmaceuticals and cleaning products (disinfectants and detergents). We met the staff concerned to discuss ways of limiting discharges of cleaning products wherever possible, for example by using different products to clean the administrative offices, which are not in the same buildings as the wards for patients.

At city level, rat extermination in the sewers is one of the sources of pollution of wastewater. As part of the project, Bordeaux Métropole tested a mechanical rat extermination solution to avoids using chemicals. We also worked with cemeteries operators to increase the use of chemicals-free weed killer solutions. These measures must be supported by communication campaigns for the general public.  For example, combating rats starts with reducing the quantity of food waste in public spaces.

Communicating to the general public is a key lesson, because many of the micropollutants found in wastewater are produced by our everyday habits. Simple changes of habits can help to reduce our use of products containing micropollutants, thereby reducing the quantities released into the natural environment.

Particularly close attention was paid to the reproducibility of the methods and solutions implemented. Thanks to its partnership-based and global approach, extending from the sources of micropollutant emissions to their impacts and the existing solutions, the REGARD project defined a methodology that can be deployed in other places, and developed new decision-support tools for network operators and local authorities.

*Bordeaux Métropole, the LYRE and CIRSEE (SUEZ research centres), Bordeaux University, Bordeaux Montaigne University, the CNRS, the IRSTEA, the INERIS and Cap Sciences.


Find out more about the REGARD project on the  dedicated website.

Find out more about the technical solutions to treat micropollutants.