Urban wastewater treatment - Concepts, pumping and pretreatment facilities

Implementation of the European Council Directive of May 21, 1991 concerning urban waste water treatment (also known as the UWW Directive) has represented a major challenge for many European Union member states, including France. The latter has had to make substantial efforts, including the construction of new urban wastewater treatment plants (STERU), in order to comply with the provisions of this text.

Efforts are continuing today, and will continue in the future, to ensure that our sewage and wastewater treatment facilities meet the standards imposed by the directive. This includes, in particular, upgrading and modernizing existing infrastructures, including, in some cases, very large-scale work on existing facilities. This often entails substantial financial investment and long-term planning for local authorities.

In 2024, the European institutions will be finalizing a new directive on the treatment of wastewater. It has already been established that it will lead, among other things, to the more systematic implementation of tertiary and complementary treatments.

One of the requirements of the ERU directive currently in force is that agglomerations must set up an ERU collection system, which must be systematically linked to an ERU treatment facility. However, in cases where the installation of a collection system is unjustifiable, either for lack of environmental benefits or due to prohibitive cost, the directive authorizes the use of alternative solutions, such as individual sewerage systems or other suitable devices, provided they guarantee an equivalent level of environmental protection.

The new member states, as well as countries in the process of joining the European Union, must comply with this directive within a timeframe acceptable to them, and with substantial aid from Europe. Construction and upgrading will continue in France and Europe, while the maintenance and operation of treatment plants are ongoing processes of major importance. Mastering ERU treatment techniques is therefore essential for the application of this and future directives.

For these reasons, we have put together a set of three articles outlining the various ERU treatment methods that enable the multiple requirements of the directive to be met. It also examines in detail the tertiary and complementary treatments that will have to be adopted more systematically in the future as a result of the future text currently being finalized at European level.

This article covers the following topics:

• requirements for effluent from STERU ;

• best practices for selecting technical processes ;

• ...