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Published on August 25, 2020

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Wastewater treatment for the benefit of the population, the city and the environment

As the leading public service for wastewater management in the Paris region, the Syndicat interdépartemental pour l'assainissement de l'agglomération parisienne (SIAAP) depollutes the water used every day by 9 million people in the Paris region for their domestic and industrial uses, as well as the Paris region’s rainwater. However, this mission requires preventing any disturbance or risks to people and nature.


- Crédits : voloshin311 - AdobeStock

To monitor and control the possible inconveniences generated by its installations, the SIAAP has set up environmental observatories. The purpose of these observatories is to monitor the development of the olfactory and acoustic nuisances of its facilities, understand how they spread in the environment and estimate the amount of inconvenience suffered by the populations. In this context, we support the SIAAP in carrying out measurement campaigns (chemistry, odours/olfactometry1, ventilation) for the regulatory control of its installations, in setting up devices with electronic noses to monitor odours, or indicators for the emissivity of harmful chemical compounds such as hydrogen sulphide. Local residents are not necessarily aware of this constant monitoring, because it they can’t see it! And yet, it is the preservation of their health and their living environment that motivates this approach.

The same applies to the risk of accidents, such as fire or explosion. This risk exists, and it should neither be over- nor underestimated, but taken into account at its fair value. Egis recently carried out an ATEX2 study for the SIAAP for its Seine Aval site, the largest wastewater treatment plant in Europe, located in a wooded area near Achères, Maisons-Laffitte and Saint-Germain-en-Laye (Yvelines department). It is one of SIAAP’s main anaerobic digestion sites. This involves implementing a rigorous and standardised approach to guarantee the optimal safety of the installations and to prevent any risk for the neighbouring municipalities. With the same discipline, we help the SIAAP to make the facilities that discharge wastewater into the Seine reliable, in order to guarantee the population a clean and healthy river for water sports and tourist activities. Thus, the well-being of the user-inhabitant is always the guiding force behind what we do.


1 Egis has a COFRAC-accredited laboratory for odour measurement in accordance with standard NF EN 13725 (dynamic olfactometry).
2 Explosive atmosphere

The authors

Hélène Piet,

Environment Project Manager


Ludovic Pattyn,

Expert in Industrial Risks



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