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February 2022
City of Sete, South of France

Modernisation of the Eaux-Blanches Wastewater Treatment Plant



The project involved the modernisation of a wastewater treatment plant in the city of SETE located in the south of France. The modernisation will enable treatment of increased capacity of wastewater that can be treated, allowing to continue the very sensative and important process of shellfish farming activity in this area.

icon The Project Targets

  • Expand treatment capacity to reach quality requirements of the aquatic environments
    including very important shellfish farming activity.
  • Acquire an efficient installation, integrated into its environment while respecting the objectives
    of sustainable development.
  • “Carbon neutral”: Producing 90% of the energy consumed through the methanization of sewage sludge, within an energy recovery unit.
  • Filter all the bacteria and some viruses to guarantee “bathing water” quality discharge.
  • Treat rainwater thanks to a buffer basin of 6,000 m3.

icon The Solution

  • Realization of the outlet manifold
  • Realization of treatment basin connections
  • Realization of the process water network

HDPE pipes SDR 17 to SDR26
Welded connection: EF up to and including 315mm, above 315mm EF or Butt fusion.


1000mm SDR26 Fabricated Y with 53° outlet + 4 PLASSON Super LightFit PN 6 couplers. An essential part that allows a connection of the new station to the treated wastewater discharge outfall.

The PLASSON solution provided the best means (compared to cast iron and steel solutions offered) to integrate assembly constraints, in particular the installation time, due
to the important ecological issue.

As expected, the installation of the collector required an installation of a “by-pass”, in order to reject part of treated water of the Station in the channel of La Peyrade river and fishing structure crossing the city, not intended to receive effluents directly from the treatment plant!

In order to preserve the natural environment, limit the bacteriological impact of the water and all risks on shellfish-growing areas while
working, a system for disincfection of the treated waters was put in place.

The system ensured admissible microbiological flows during installation of the collector. The entire shellfish farming field was informed and made the relevant preparations. A maximum period of 4 days was given for construction of the collector.

4 SUPER LIGHTFIT PLASSON and 1 TEE to the rescue of oyster beds!

Creation of treatment tank connections

The PLASSON solution provided the ability to combine two welding techniques depending on the diameters and site configurations: electrofusion and butt welding.
Major advantages in favor of PLASSON PE solution: light weight, flexibility, sealing thanks to the welded solution, no corrosion, chemical insensitivity to effluents (wide spectrum), adaptation to the differential ground settlements created by the basins.

Realization of the process water network (fresh or drinking water)

Sealing provided by welding.
PLASSON supplied LIGHTFIT couplers and shaped fittings (elbows, tees, stub end) from diameter 180mm to diameter 800mm.
Electric scraper PF 355-1200mm

PLASSON solution strong points

  • Easy installation EF PLASSON couplers (no pre-heating)
  • Sliding capacity (thanks to equipement)
  • Ability to supply shaped parts on demand: example of the 53° tee (not possible in cast iron,possible in steel but uncompetitive solution due to high cost)
  • Joint work with the installation company to develop and build a technical engineering solution
  • Training and on-site assistance


The most sensitive construction consisted in the installation of the collector. We had declared 36 hours and achieved it in 24 hours. We worked day and night. I chose the PLASSON solution because based on my experiance, it is the most reliable brand on the market.
Why PLASSON? For its service, assistance, delivery times and excellent reliability. It is essential to work with positive partners.
Mr. Saintin General Manager, POLYPLAST
The critical point laid in the installation of the manifold.
Once we demonstrated our strengths, we joined the project. The first project involving 1000mm fittings for PLASSON France!
Ms. Corinne Collas Development Manager, PLASSON France
The validation of technical director of the Aglopole, was essential.
The collaboration with the company POLYPLAST has made it possible to anticipate needs.
Mr. Eric Foultier Sales Rep SE, PLASSON France