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Municipal Case Studies

Guéthary - France

Perfectly integrated into the landscaped site, the ultra-compact water treatment plant of Guéthary, Saint-Jean de Luz and Acotz benefits from the most advanced technologies thus ensuring that its performance surpasses the required standards.

Disinfection (Virus free)
No odour and/or noise pollution
Flexible process capacity
Operating flexibility
Easy operation
Centralized operation
Well-integrated into the landscape

Capacity: 4 100 PE in low season (755 m3/day), 10 000 PE in high season (1 600 m3/day), + 2 000 m3/day during raining periods
Maximum flow rate: 300 m3/h
Buffer tank : 1 300m

A virus free water treatment plant

MSE, a Veolia Water Technologies subsidiary, has created an exemplary "VIRUS FREE" treatment process comprised of biological treatment with membranes, a physical barrier and UV sterilization and disinfection. Treated effluents are released into the sea.

These processes protect the local environment from pollution - even with the plant's large variations in hydraulic and organic pollutants - and keep the sea accessible for fishermen, surfers and swimmers throughout the year.

Guethary's wastewater treatment

The Biosep™ process is distinct in its combination of biological treatment by activated sludge and membrane filtration.

Its compact design has enabled the plant's capacity to be increased to 10 000 PE. The refurbishment of existing works has allowed for the centralisation of urban wastewater and storm water treatment.
Its performance makes this new technology suitable for coastal municipalities or those wishing to recycle treated waters.

The membranes are also suitable for the following situations :

  • Large variations in quantity/quality of water to be treated
  • Lack of space
  • Strict discharge regulations (reduction of carbon pollution, removal of SS, disinfection)
  • Discharge to environmentally sensitive areas

Discharge quality


Discharge levels

Requested levels

Levels guaranteed by MSE

DBO5 25 mg/l 5 mg/l
COD 125 mg/l 30 mg/l
SS 30 mg/l < detection threshold
TN 15 mg/l 15 mg/l
Bacteriology E.coli: 100/100 ml E.coli: 25/100 ml
Virology - Virus free (corresponding to classic virus detection methods)

General Diagram

Guéthary schéma

The treatment plant and water pollution controls