Septage treatment: one plant, two setups

Animation illustrating the wastewater routing along the two setups

Clic on each setup to follow the water’s progression, from the particular individual to the stream

Winter Setup

In the winter, the filtrates of the septage plant are treated on the existing ponds and rejected in the Montrosies creek. The outlet meet the outlet quality requirements despite the high pollutant contents in the filtrates (and therefore at the ponds entrance) because it takes a long time for the filtrates to exit the ponds (over 400 days, against 60 days for a classic pond system).

Summer Setup

In the summer i.e. from March to November approximately, the filtrate is discharged to a plantation of poplars and eucalyptuses which absorbs them entirely, according to the “zero rejection” requirement of the Water Authority: no discharge of treated septage in the river system. This approach cancels the polluting contribution of the treatment plant in a period of maximum sensitivity of the creeks, with here again very little energy consumption.

Lagunes vue du ciel
Two treatment ponds (winter regime)

The primary ponds are integrated into the Nègrepelisse septage plant’s treatment steps.


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