Presentation

When the ecological treatment of waste water falls into step with the natural environment

Located amid the peripheral marshes around Rochefort, in a wonderfil green belt of some 400 hectares, between the river Charente and the town, lies the treatment wetland – a feature that uses a unique natural water purifying technique known as lagooning and an excellent site for watching aquatic birds.

 

Nature on the doorstep of town

The technique of lagooning allows the entire volume of wastewater from the town to be eco-purified in vast retention pools (35 hectares in area), by exposing it to the action of sun, wind and micro-organisms.

This eco-friendly technique encourages the growth of plankton, an essential source of food to a host of water birds (160 species are regularly observed). Consequently, thousands of Shoveller ducks, scaups, pochards, coots, grebes, terns, Pygmy seagulls… are attracted by the peaceful setting and the abundance of food which enables them to stock up for winter or their migratory journeys.

After being processed, the water pumped back into the natural environment is of “bathing water” quality, suitable for activities associated with the Charente estuary.

Silt reusing and energy harnessing

On arrival at the lagooning station, wastewater undergoes a physical process: screening, degreasing and grit removal. The residual mud is decanted and harvested, then goes through a biogas reactor. Here, chemical reactions ‘mineralise’ this resulting mud into compost from which methane is extracted to be used for powering a co-generator, which produces electricity.

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